Group Title: disinfection of public water supplies with elemental iodine
Title: The Disinfection of public water supplies with elemental iodine
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 Material Information
Title: The Disinfection of public water supplies with elemental iodine
Physical Description: xvi, 200 leaves : illus. ; 28 cm.
Language: English
Creator: Kinman, Riley Nelson, 1936-
Publication Date: 1965
Copyright Date: 1965
Subject: Water -- Purification   ( lcsh )
Iodine   ( lcsh )
Civil Engineering thesis Ph. D
Dissertations, Academic -- Civil Engineering -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
Thesis: Thesis - University of Florida.
Bibliography: Bibliography: leaves 194-199.
General Note: Manuscript copy.
General Note: Vita.
 Record Information
Bibliographic ID: UF00098222
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000559036
oclc - 13433372
notis - ACY4482


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December, 1965

II 3I 1262 0IIII I3 2 III
3 1262 086463824


I dedicate this work to those who have contributed most to my

education, namely, my beloved parents and my committee chairman, Dr.

A. P. Black. Dr. Black has been a wonderful guide and an example to

follow in my profession. He has provided inspiration, enthusiasm,

and competent advice throughout my graduate work for which I am truly


I wish to express my sincere gratitude to Professors John E.

Kiker, Jr., T. deS. Furman, George B. Morgan, and Tommy R. Waldo, who

served on my committee and assisted me with their teaching.

I am indebted to Richard P. Vogh and Margaret E. Whittle for

their assistance in my research, and to Conrad Dutton, Herbert C.

Kelley, and Captain R. 0, Carroll for their cooperation and assistance

at the institutions at Lowell, Florida. Many others at the institu-

tions have rendered valuable assistance for which I am very grateful.

I wish to thank Mr. H. J. Cordle, Director of the Chilean

Iodine Educational Bureau, for his advice and assistance. My thanks

to Mrs. Janice Larson for her fine help during the performance of this

work and for typing the final manuscript.

My deepest thanks go to my wife, JoCeil, for her patience,

encouragement, and help throughout this endeavor.

I wish to acknowledge financial support from the Division of

Water Supply and Pollution Control, Public Health Service, WPD-19-03-65

and Training Grant 8 T1 ES 11-04, without which this research could not

have been accomplished.

R. N. K.




ACKNOWLEDCGMNTS ......... ... ........... ii

LIST OF TABLES .......... .... .... ...... vii

LIST OF FIGURES ..... . . . . . . . . x

ABSTRACT. ......... .. ... ........... xiv


I. INTRODUCTION ................... 1

II. IODINE THE ELEMENT ................. 4

III. LITERATURE SURVEY ................ 8


Effect of pH .................. 23
Hydrolysis of I ................ 24
Effect of pH on Formation of Hypoiodite Ion . 25
Formation of Tri-iodide Ion, 13 . . ... 26
Formation of Iodate Ion . . . . .... 26
No Reaction with Ammonia . . . . . . 27


Iodine Disinfection at Lowell, Florida ..... . 29
Description of Water Systems . . . ... 29
Station No. 1 . . . . . . .... 29
Station No. 2 ................ 30
Chemical Characteristics of the Well Waters . 39
Iodination Procedure . . . . . .... 42
The Feeding of Elemental Iodine to Water . .. 43
Chemical Control ................ 49
Iodine Feed at Lowell . . . . . .... 59
Bacteriological Control . . . . . ... 60
Bacteriology During the Chlorination Period . 62
Bacteriology During Twenty-Two Months of
Iodination ................. 67
Special Distribution System Bacteriological Study 74
Physiological Control . . . . . . .. 78
Medical Assessment and Selection of the Sample
Population ................. 78



Physiological Response to Iodine Intake . . .. 78
Aesthetic Considerations . ... ... . .83
Public Acceptance at Lowell . . . . . 85
Disinfection of the Water of the University of
Florida Swirnming Pool with Iodine . . . .. 86
Introductory Remarks . . . . . . .. 86
Swimming Pool Characteristics . . . . .. 86
Disinfection System . . . . . . .... 89
Water Analysis .................. 90
lodination Criteria and Procedure .. . ..... 92
Chlorination Criteria and Procedure . . . .. 93
Filtration . . . . .. .. . . 93
The Weather . . . . . . . . . .. 93
Pool Bathing Load . . . . . . .... 95
Sampling Procedures . . . . . . .... 97
Chemical Samples ............... 97
Bacteriological Samples . . . . . .. 97
Bacteriological Results . . . . . .... .. 98
Algae Control ................... 103
Physiological Control ........ . . . 104
Aesthetic Considerations . . . . .... 105
Tastes and Odors . . . . . .... 105
Color . . . . . . . . . . 108
Bather Acceptance ................ . 109
Disinfection Cost . . . . . . . .. 14
Laboratory Study Section . . . . . . .. 118
Saturator Design . . . . . . . .. 118
Discussion ........ .. .. ........ 124
Experimental Saturator No. 1 September 7, 1963 -
October 29, 1964 ....... ........... .127
Saturator body ..... .. .......... 127
Saturator bottom ................. 127
Iodine bed support . . . . . . . .. 127
Iodine bed . . . . . . . . . .. 128
Saturator piping . . . . . . . .. 128
Saturator top ..................... 128
Piping sealer .................. 128
Determination of the Iodine Demand of Water from the
Three Wells at Lowell . . . . . . ... 130
General Discussion . . . . . . ... 130
Experimental Technique . . . . . . .. 131
Procedure ..................... 132
Discussion of Results . ... ... .... 132
The Effect of Ammonia in Iodine Disinfection . .. 139
Experimental Techniques . . . . . . .. 141
Procedures ................... 141
Discussion of Results ............... 141
Effect of Added Raw Sewage on the Halogen Demand of
Lowell Well Water . . . . . . . . 147
GOneral Discussion .............. 147
Experimental Techniques . . . . . . . 148


Procedure ................... .. 149
Discussion of Results .............. 151
The Effect of Phenol in Iodine Disinfection ... .160
General Discussion . . . . . . .... 160
Experimental Techniques . . . . . . .. 162
Procedure . . . . . . . . ... . 162
Discussion of Results ............... 166
Effect of Iodine on Copper . . . . . .... 166
Experimental Techniques . . . . . ... 167
Discussion ................... 168
Effect of Iodine on Materials of Construction . .. 175
Introduction ................... 175
Procedure .................... 176
Immersion Test Procedures ............ 176
Discussion of Immersion Test Results . . . 176
Iodine-Resistance of Construction Materials at
Lowell ...................... 178
Material: Hastelloy C .............. 178
Material: Stainless Steel Type 304 . . . . 179
Material: Stainless Steel Type 347 . . . . 179
Material: Stainless Steel Type 316 . . ... 179
Material: Inconel . . . . . . . ... 180
Material: Graphite ................ 180
Material: Glass .................. 181
Material: Saran .................. 181
Material: Teflon ................. 182
Reoxidation of the Iodide Ion . . . . ... .182
Introduction ................... 182
Experimental Technique . . . . . .... 184
Procedure ... .. . ..... . ..... .186
Discussion ..... ......... ....... 186

VI. SUMMARY ............ ...... .. .. 189

LIST OF REFERENCES ........... ..... ... 194

BIOGRAPHICAL SKETCH .......... ...... ...... 200


Table Page

1. Iodine Content of Water from Four of the Great Lakes . 5

2. Iodine Content of Water from Some United States Rivers . 6

3. Iodine Content of Water Supplies in Iraq ........ 7

4. Percent of Free Available Chlorine in the pH Range 4-10 23

5. Percent of I, Residual of 0.5 ppm Present . . ... 24

6. Lowell Water Consumption Data, May 1963 to September 1965. 40

7. Chemical Analyses of Water from Individual Wells . .. 41

8. Trace Elements in Water from Well No. 1 . . . . 42

9. Iodine Residuals at Ends of the Two Water Systems for
Indicated Iodine Dosages . . . . . . .... 58

10. Typical Free Chlorine Residuals in Parts Per Million in
the Distribution Systems Prior to Iodination ...... 68

11. Typical Study Showing the Effect of Contact Time on
Bacterial Kill, May 3, 1965 .............. 75

12. Typical Study Showing the Effect of Contact Time on
Bacterial Kill, May 10, 1965 . . . . . .... 76

13. Typical Study Showing the Effect of Contact Time on
Bacterial Kill, May 17, 1965 . . . . . .... 77

14. Chemical Analysis of the University of Florida Swimming
Pool Water . . . . . . . . ... . .... 91

15. Swimming Pool Data During lodination . . . . .. 94

16. Pool Bathing Loads During lodination . . . . .. 96

17. Pool Bathing Loads During One Week of Supervised
Chlorination ....................... 96

18. S-inmminr ?ool Data During One Week of Supervised
Chlorination ....................... 98


Table Page

19. Bacteriological Data for Period May 19-June 15 . . .. 102

20. Summary of Bacteriological Data, June 16-July 17 .... .103

21. Medical Test Results of University Swimming Pool Study .105

22. Swimming Pool Questionnaire Data . . . ...... 111l

23. Reasons Mentioned for Preference of C12 Over 12 ... 112

24. Reasons Mentioned for Preference of 12 Over C12 ... 112

25. Effect of Bed Depth and Rate of Flow on Rate of Solution
of Elemental Iodine . . . . . . . . .. 119

26. Typical Iodine Solution Strengths from Saturator No. 1 .122

27. Concentration of Random Monthly Samples from Saturators 126

28. Typical Iodine Demand of Water from Three Wells, May 1963. 133

29. Typical Iodine Demand of Water from Three Wells, May 1964. 133

30. Typical Iodine Demand of Water from Three Wells, May 1965. 134

31. Effect of Added Ammonia on Iodine Demand ........ 142

32. Effect of Added Ammonia on Chlorine Demand ...... 142

33. Effect of Ammonia on Rate of Kill . . . . .... .146

34. Typical Constituents of Human Feces ........ . 149

35. Typical Constituents of Human Urine . . . . .. 150

36. Effect of Sewage on Chlorine and Iodine Demand ... .158

37. Effect of Sewage Concentration on Iodine Demand .... .158

38. The Effect of Phenol on Taste or Odor and Iodine Demand 163

39. Iodine Demand of Water Exposed to Metallic Copper . . 169

40. Materials that are Resistant to Iodine Under Suitable
Conditions ..... ... .... ... .. .... .. 175

41. Common Construction Materials Resistant to Iodine . .. 177


Table Page

42. Inorganic Oxidants Tested for Release of I, from I- in
Water Distribution Systems . . . . . .... 188



Figure Page

1. Aerial Photograph of the Florida Correctional Institution
for Women .................. ..... 31

2. Aerial Photograph of the Forest Hill School for Girls . 31

3. Forest Hill School for Girls . . . . . ... 32

4. Florida Correctional Institution for Women ...... 33

5. Florida Correctional Institution Male Unit . . ... 34

6. Original Water System, Womens Prison and Girls' School . 35

7. Monthly Water Use at Station 1, May 1963 to September 1965 36

8. Original Water System, Mens Prison . . . . .. 37

9. Monthly Water Use at Station 2, September 1963 to
September 1965 ..................... 38

10. Station No. 1 at the Beginning of the Project . . . 44

11. Station No. 1 with lodination Equipment Installed . . 4

12. Iodine Solubility in Water . . . . . ... 45

13. Iodine Feed Apparatus . . . . . . . .... 46

14. Iodine Saturator, Station 1 . . . . . .... 47

15. The Upper Portion of the Iodine Saturator in Station No. 1 50

16. The Lower Portion of the Iodine Saturator in Station No. 1
with Adjacent Chemical Metering Pumps . . . .... 50

17. Adapted Water System, Women's Prison and Girls' School . 51

18. Adapted Water System, Men's Prison ........ 52

19. Interior of Station No. 1 ...... ............ .53

20A Aerial Photograph of Male Unit . . . . .... 53

Figure Page

21. Typical Daily Chart from the Iodine Residual Recorder Which
Monitors the Iodine Feed . . . . . . ... 54

22. Typical Weekly Chart from the Iodine Residual Recorder
Which Monitors the Iodine Feed . . . . . ... 55

23. Typical Distribution System Weekly Chart from Iodine
Residual Recorder. The Iodipe Feed at this Time was 0.40
Parts Per Million .. . . ............... 57

24. Iodine Feed at Lowell, October 28, 1963 to September 1965 61

25. Bacteriological Data During Period of Disinfection with
Calcium Hypochlorite, February 1963 to October 28, 1963. 63

26. Bacteriological Data During Period of Disinfection with
Calcium Hypochlorite, February 1963 to October 28, 1963. 64

27. Bacteriological Data During Period of Disinfection with
Calcium Hypochlorite, February 1963 to October 28, 1963. 65

28. Bacteriological Data During Period of Disinfection with
Calcium Hypochlorite, February 1963 to October 1963. . 66

29. Bacteriological Data During 22 Months of iodination,
October 28, 1963 to September, 1965. . . . . .. 69

30. Bacteriological Data During 22 Months of Iodination,
October 28, 1963 to September, 1965. ........ .. 70

31. Bacteriological Data During 22 Months of Iodination,
October 28, 1963 to September 1965. . . . . ... 72

32. Bacteriological Data During 22 Months of Iodination,
October 28, 1963 to September 1965...... ..... . 73

33. Radioactive Iodine Uptake, Mean Values One Standard
Deviation ........................ 80

34. Protein Bound Iodine, Mean Value One Standard
Deviation . . . . . ....... .. .. .. 81

35. Serum Thyroxine, Mean Value t One Standard Deviation . 82

36. Urine Iodide in 50 Subjects Using lodinated Water Which
Contained 0.6 Parts Per Million Elemental Iodine . . 84

37. Pool Recirculation Pattern, Summer of 1964 ....... 88


Figure Page

38. Bacteriological Data During lodination of the University
of Florida Swimming Pool, May 19 to July 17, 1964 .... .99

39. Bacteriological Data During Chlorination of University of
Florida Swimming Pool .................. 100

40. Effect of Swimming in Water Containing 5 ppm Iodine on
RAI Uptake ...... ... ... ....... ..... 106

41. Effect of Swimming for One Month in Water Containing
5 ppm Iodine on PBI . . . . . . . . . 107

42. Effect of Concentration of Iodide Ion on Molecular Ratios
HIO / CIJ at Various pH Values. These Calculations
Neglect Some Decomposition of HIO Which Takes Place at pH
Values Above 9.0 ..................... 110

43. Swimmer Disinfectant Preference. University of Florida
Swimming Pool, Summer of 1964 . . . . . . . 113

44. Iodine and Chlorine Demand Curves for Water from the
University of Florida Swimming Pool, June 1964. . . ... 115

45. Cost of Swimming Pool Disinfection. University of Florida
Swimming Pool, June 16, 1964 to July 17, 1964 . . .. 117

46. Experimental Iodine Saturator No. 1. Completed September
7, 1963 ....... . ................... .121

47. Experimental Iodine Saturator No. 2. Completed October 4,
1963 .... ... ........ ........... 123

48. Experimental Iodine Saturator No. 4. Completed March 4,
1964 and Installed at Station 2 on January 7, 1965 . . 125

49. Iodine Demand Curve of Lowell Well Water (May 1963) . . 135

50. Iodine Demand Curves of Lowell Well Water (May 1964) . 136

51. Iodine Demand Curves of Lowell Well Water (May 1965) . 137

52. Chlorine and Iodine Demand Curves of Lowell Well Water . 138

53. Effect of Added NH3 on Type and Persistence of Chlorine
and Iodine Residuals .. . . . . . . .. 140

54. Effect of Added NH3 on Type and Persistence of Chlorine
and Iodine Residuals . . . . . . . . .. 143


Figure Page

55. Effect of Added NH3 on Type and Persistence of Chlorine
and Iodine Residuals .................. 144

56. Effect of Added NH3 on Type and Persistence of C1, and
I, Residuals ...................... 145

57. Effect of Domestic Sewage on the Persistence of Iodine
Residuals ....................... 152

58. Effect of Domestic Sewage on the Persistence of Chlorine
and Iodine Residuals .................. 153

59. Effect of Domestic Sewage on the Persistence of Chlorine
and Iodine Residuals .................. 154

60. Effect of Domestic Sewage on the Persistence of Chlorine
and Iodine Residuals ................. 155

61. Effect of Domestic Sewage on the Persistence of Chlorine
and Iodine Residuals .................. 156

62. Effect of Domestic Sewage on the Persistence of Iodine
and Chlorine Residuals . . . . . . .... 157

63. Effect of Phenol on Iodine Demand . . . . .. 164

64. Effect of Phenol on Iodine Demand . . . . .. 165

65. Iodine Demand of Water Exposed to Metallic Copper . 170

66. Iodine Demand of Water Exposed to Metallic Copper . 171

67. Iodine Demand of Water Exposed to Metallic Copper . 172

68. Iodine Demand of Water Exposed to Metallic Copper . 173

69. Iodine Demand of Water Exposed to Metallic Copper .. 174

70. Effect of Monochloramine on Persistence of Iodine
Residuals . . . . . . . .... ...... 185


Abstract of Dissertation Presented to the Graduate Council in
Partial Fulfillment of the Requirements for the Degree of
Doctor of Philosophy



Riley N. Kinman

December, 1965

Chairman: Dr. A. P. Black
Major Department: Civil Engineering

The water in two water systems supplying three Florida correc-

tional institutions and serving a total of approximately 800 individuals

has been continuously disinfected with iodine for a period of two years

under carefully planned chemical, bacteriological and medical controls.

The physical and chemical properties of iodine make it particu-

larly suitable for use as a water disinfectant. Although its water

solubility is not high, its saturated solution is sufficiently concen-

trated for feeding purposes. Its low chemical reactivity, least of all

the halogens, means that lower residuals are more stable in the pre-

sence of organic or other oxidizable material, and the possibility of

the production of tastes and odors by such reactions is minimized. No

difficulties have been encountered in continuously feeding the element

in saturated water solution to provide any desired dosage with an over-

all accuracy of plus or minus .05 parts per million.

Of over 1000 samples collected from the two systems for bacteri-

ological analysis during a 22-month period of iodination, only about

2% were unsatisfactory.


Medical studies included the assessment of the three indices of

thyroid function, namely, radioactive iodine uptake (RAI), protein bound

iodine (PBI) and serum thyroxine (T.). Each subject received the series

of tests twice before iodine feed was begun and 30 days apart, following

which the tests were made on all subjects one, three, seven, and ten

months after beginning the feed of iodine. The RAI intake dropped from

about 17% at the beginning of the study to about 2% at the end. Values

for PBI increased somewhat but the mean for the group was still within

the range of values found in normal individuals. No significant change

in the mean value for serum thyroxine was found. There has been no

apparent change in the physical examination and in the size of the

thyroid gland. No allergic reactions attributable to iodine have been

found. There is no evidence to date that iodine under these experimental

conditions has any detrimental effect on general health or thyroid


In dosages up to 1.00 parts per million, iodine produces no

discernible color, taste, or odor in water.

A swimming pool study was made to investigate the possibility

that iodine may be absorbed by the skin of individuals exposed to water

containing it. Twenty-two subjects received the same series of tests

as those used at Lowell before and after swimming throughout a period

of one month in pool water disinfected with iodine. Average values for

the group for RAI, PBI and T, were not significantly changed and no

evidence of allergy or change in size of the thyroid gland was detected

in any subject during the study.


Both iodine and chlorine were shown to be effective disinfecting

agents in the concentration range 0.3 0.6 parts per million and at pH

values between 7.3 7.6. It is in the disinfection of swimming pool

water that the ability to readily reoxidize and reuse the iodide ion

pays greatest dividends. In this study a careful record was kept of

all chemicals used for disinfection and pH control and accurate data

covering disinfection were available. It was found that whereas the

cost of chlorine disinfection had averaged $7.98 per day, the cost for

disinfection with iodine was $4.70 per day. It is possible to disin-

fect swimming pool water with iodine at a cost approximately half that

of chlorine.

These studies indicate that iodine is fully as effective as

chlorine for the disinfection of public water supplies and that it

possesses a number of advantages over chlorine when used for that pur-




Iodine possesses the highest atomic weight of the four halogens,

is least soluble in water, is least hydrolyzed by it, has the lowest

oxidation potential, and reacts least readily with organic compounds.

These somewhat negative characteristics might at first sight appear to

be limiting factors with respect to its use for the disinfection of

water. Actually, however, just the reverse is the case because, taken

collectively, they mean that low iodine residuals should be more stable

and therefore persist longer in the presence of organic or other oxi-

dizable material than corresponding residuals of any of the other halo-

gens. The high chemical reactivity of chlorine and its ability to

react with organic material by oxidation, by substitution, or by

addition, constitutes perhaps the greatest drawback to its effective-

ness for water disinfection. The ideal water disinfectant would be

some material, weak chemically and unable to participate in such re-

actions but which, at the same time, would possess bactericidal, cysti-

cidal, and viricidal properties equal to or superior to those of


Although iodine, in aqueous or hydroalcoholic solutions has had

official status in the U. S. Pharmacopoeia since 1830, and has been an

essential item in the home medicine cabinet for more than a century,

recognition of its remarkable properties as a water disinfectant has

been very slow to develop.1'2'3 It was not until 1953 that Chang and



Morris '5 published their important studies of its effectiveness against

bacteria, viruses, and cysts of E. hystolytica. Their studies were

primarily responsible for its adoption by the military for the disin-

fection of canteen water in the field. In 1959, Black, Lackey and

Lackey published the first study of its effectiveness for the disin-

fection of swimming pool water and this work, together with that of

others,7,8,9 resulted in its tentative approval in 1962 by the U. S.

Public Health Service for swimming pool disinfection, with the proviso

that the maximum concentration of iodine in all forms shall not exceed

five parts per million. To date, its use for this purpose has been

approved by the states of Ohio, Pennsylvania, Illinois, North Carolina,

Georgia, Texas and, with certain limitations, by the states of Florida

and California.

The next logical step in the development of iodine for water

disinfection, indicated by the remarkable successes in the aforementioned

studies, was to use iodine for the disinfection of a public water supply

under careful chemical, bacteriological and physiological control. This

study was designed and initiated under these conditions with the follow-

ing primary objectives:

1. To demonstrate the effectiveness of iodine for the disin-

fection of public water supplies.

2. To determine the physiological effects of iodine on a human


3. To evaluate the chemistry and technology of iodine under

actual conditions of practical water disinfection.


In order to accomplish these objectives and others, elemental

iodine was and is being used to disinfect the public water supplies of

three state correctional institutions. These institutions are The

Forest Hill School for Girls, The Florida Correctional Institution for

Women, and The Florida Correctional Institution, Male Unit, all of

Lowell, Florida. Iodine was and continues to be used to disinfect the

University of Florida olympic size swimming pool. The data and results

from these studies and the laboratory studies carried out in conjunction

with these applied studies are presented and described in the follow-

ing pages. These data were obtained during the period February, 1963

to September, 1965.


Iodine has an atomic number of 53 and an atomic weight of 126.91.

It is a halogen from Group VII of the periodic table. It is the only

halogen that is a solid at room temperature. Its vapor pressure at

25C is only 0.31 mm of mercury, while that of bromine is 215 mm and

that of chlorine is 5300 mm of mercury. The word iodine is derived

from the Greek word "ioeides" meaning "violet colored." Its principal

valence numbers are: -1, +1, +3, +5, +7. Iodine is a simple element

with one stable atomic species of mass number 127 and it has ten or

more radioisotopes. Of these, 1131 with a half life of 8.08 days is

the most useful tracer.

Iodine is the 47th most abundant element in the earth's crust.

It is widely distributed in nature, but only in very small concentra-

tions. Sea water contains about 0.05 parts per million. Certain sea-

weeds can extract iodine from sea water and accumulate it. Laminaria

may be 0.45 percent iodine on a dry weight basis. Fucus is the next

best seaweed source of iodine. Other sources of iodine in commercial

concentrations include sponges, coral, deep oil well waters, springs in

California, Java, Russia, and Italy and in the caliche nitrate deposits

of Chile, which are the world's major source of iodine at present. It

is found in trace quantities in many lakes and rivers. Tables 1 and 210

give the concentration of iodine found in certain lakes and rivers in

the United States. Table 3 presents like data for some water supplies



in Iraq.ll These data show that although iodine is widespread in nature,

its concentration is extremely low.

Table 1

Iodine Content of Water from Four of the Great Lakes

Lake Iodine Content, Parts Per Billion

Superior at Duluth, Minn. 0.01

Superior at Marquette, Mich. 0.02

Michigan at Milwaukee, Wis. 0.015

Michigan at Winnetka, Ill. 0.10

Michigan at Chicago, Ill. 0.12

Erie at Cleveland, Ohio 0.86

Ontario at Toronto, Canada 1.45

Average 0.37


Table 2

Iodine Content of Water from Some United States Rivers10

River Iodine Content, Parts Per Billion

Mississippi at Minneapolis, Minn. 0.88

Mississippi at St. Paul, Minn. 0.83

Mississippi at St. Louis, Mo. 3.52

Mississippi at New Orleans, La. 7.70

Missouri at Kansas City 1.69

South Platte at Denver, Colo. 0.77

Scioto at Columbus, Ohio 0.21

Cumberland at Nashville, Tenn. 0.22

Susquehanna at Harrisburg, Pa. 0.23

James at Richmond, Va. 0.60

Potomac at Washington, D. C. 0.72

Oconee at Atlanta, Ga. 3.20

Average 1.71


Table 3

Iodine Content of Water Supplies in Iraql

Location of Supply

Iodine Content, Parts Per Billion

Mosul 3

Tell Afar 17.5

Baghdad 3.5

Dohuk 7

Akra 4


Iodine was discovered in 1811 by Bernard Courtois while making

nitrates for Napoleon's Army. Courtois sent a sample to J. L. Gay-

Lussac who named it "iode" from the Greek for "violet colored." Gay-

Lussac studied iodine and prepared many of its compounds.

The first practical use of iodine was in medicine in Switzerland.

Dr. Coindet13 used tincture of iodine to cure goiter in Geneva, Switzer-

land in 1819. In 1839, Davies used tincture of iodine for the

treatment of wounds. Watson1 used dilute iodine solution to treat

gonorrhea in 1867. Davaine6 was the first to demonstrate the sporici-

dal activity of iodine solutions in 1873 employing the spores of the

anthrax bacillus.

During our American Civil War tincture of iodine was carried to

the field and used in the treatment of battle wounds.

The French made an unsuccessful attempt to use iodine for water

disinfection during World War I. They added a mixture of potassium

iodide and potassium iodate to the water to be disinfected and the

iodine was to be released by lowering the pH. However, the very low pH

required presented difficulties and the trials were abandoned.

One of the earliest references to the use of iodine for the dis-

infection of drinking water in this country appeared in the Union

Pharmaceutique in May of 1915.17 Five drops per liter of a solution

consisting of 1 g of iodine, .05 g of potassium iodide, 1 g of water

- 8 -


and 8 g of 95% ethyl alcohol was deemed sufficient to disinfect water

for troops in the field.

In 1922, Major A. P. Hitchens18 of the Army Medical School stated

that polluted water is rendered "safe for drinking" by adding "one drop

of tincture of iodine to a canteen or a one-quart thermos bottle full of

water." The Iodine Tincture Official at this time contained 7% free

iodine and 5% potassium iodide.

In 1933, Beckwith and Moserl9 made what appears to be the first

attempt to evaluate the bactericidal effectiveness of chlorine, bromine

and iodine against soil bacteria and E. coli. They found that all

three halogens killed from 88 to 99.9% of the organisms, in populations

ranging from 2100-48,000 per ml, at dosages ranging from 0.5-2.0 ppm.

They found that bromine was most effective, with iodine second and

chlorine the least effective of the three. However, their methods for

determining halogen residuals left much to be desired, chlorine and

bromine residuals were determined with orthotolidine and color stand-

ards. Iodine dosages were calculated from initial concentrations and

residuals were not determined. pH values, now recognized as critical

factors, were not given and the results actually demonstrated little

more than the fact that all three halogens possess bactericidal activity

against the organisms studied.

In 1937, Pond and Willard20 concluded that tincture of iodine

7% (U.S.P.) in a concentration of two drops per liter will ordinarily

be sufficient to render any potable water innocuous within fifteen

minutes. This 7% tincture of iodine also contained 5% potassium iodide.

- 10 -

Krabauskas, Harrington and Lauter21 tested the effectiveness of

iodine for the disinfection of 25 raw waters using 7% iodine tincture as

the disinfectant. Eight drops per quart achieved sterilization with 30

minutes contact time for all of the waters tested. The bacterial counts

of the waters ranged from 50 to 86,000 per milliliter and the turbidities

from 1.6 to 490 parts per million. The pH range was 6.6 to 7.8.

In 1944, Wyss and Strandskov1 found that the bactericidal

activity of iodine is not as dependent upon concentration as is that of

chlorine. They find that the sporocidal activity of iodine was almost

independent of pH value and that the addition of equimolar concentra-

tions of ammonia, succinimide or p-toluenesulfonamide to the water at

pH 7.0 did not alter the rate of destruction of B. metiens spores.

They concluded that the sporocidal action of iodine at pH values ordi-

narily encountered is due primarily to the 12 present, but that HOI may

exert some action at high pH values. They found that the sporocidal

activity of iodine was affected to a greater extent by temperature than

was the activity of chlorine. The following four equations were pre-

sented for the chemistry of iodine in aqueous solution:

Hydrolysis 12 + H20 = HOI + + H Kh = 0.3.1012

Ionization HOI H + 0O Ka = 5.10-13

Perhalide formation I, + I" 0 13 Ki = 1.410-3

Decomposition 3HIO HIO3 + 2H+ + 2I1

The rate of iodate formation was found to depend upon pH, the HIO con-

centration and the particular buffer system employed.

Gershenfeld and Witlin2 concluded that bactericidal efficiency

- 11 -

tests of the dilute halogens (1:5000) revealed that free iodine solu-

tions displayed more effective antibacterial activity against the test

bacteria than did chlorine or bromine at 370C or 240C either in the

absence or presence of organic matter. The quantity of organic matter

present due to the added culture medium probably was a contributing

factor for these results.

Marks and Strandskov22 concluded that the killing rates of bac-

terial spores for the hypohalous acids and probably for the molecular

halogens decrease in the order: chlorine, bromine, iodine. It is not

known how well this would apply to other microbiological forms even

though this is the order of chemical reactivity in general. They com-

pared the effect of concentration on the killing times at pH 7 and 250C

and found the order of effectiveness to be chlorine, iodine and bromine.

The concentrations were plotted in equivalents and they explained their

observations by assuming that under these conditions chlorine exists

chiefly as hypochlorous acid and bromine entirely as hypobromous acid,

whereas iodine is present as molecular iodine. On a weight concentra-

tion basis, iodine was considerably less active than chlorine although

still more active than bromine.

Ficarra23 reported on the use of aqueous solutions of iodine as

skin antiseptics in 100 post-operative cases, in which there were no

post-operative wound infections. Aqueous iodine fulfills one of the

primary requisites of a skin disinfectant in that it kills bacteria in

a reasonably short time.
Chambers, Kabler, Maloney and Bryant24 conducted studies on the
Chambers, Kabler, Maloney and Bryant conducted studies on the

- 12 -

use of iodine as a bactericide. The purpose of the investigation was to

provide information which would assist in evaluating iodine as a bac-

tericide for use in water treatment. The study was specifically designed

to determine under controlled conditions, the degree to which the bac-

tericidal action of iodine is influenced by variations in exposure time,

concentration, pH and temperature. They measured the bactericidal

effectiveness of iodine against two strains of E. coli, three strains

of E. typhosa, three other species of Salmonella, three different

species of Shigella, A. aerogenes and Streptococcus faecalis. They

concluded that the minimum average iodine concentration which kills all

tested species in one minute under the most favorable conditions of pH

(pH 6.5) and temperature (20C to 26C) is 0.60 parts per million. They

found that S. typhosa was the least resistant to iodine and S. sonnei 1

was the most resistant of all cultures studied.

In May 1953, Chang and Morris discussed elemental iodine as a

disinfectant for drinking water. They reported that iodine is a suitable

agent for the emergency disinfection of water supplies, for it is effec-

tive against all types of pathogenic organisms within a reasonable time

at a concentration of a few parts per million. They attribute much of

its effectiveness to its ability to maintain substantially constant germi-

cidal efficiency in waters with high pH values and in waters containing

ammonia or other nitrogenous impurities. They found that a dosage of

eight parts per million of iodine gave complete destruction of 30 cysts

(E. hystolytica) per ml within ten minutes in most natural waters,

exceptions being waters with temperatures near 0C or with iodine

- 13 -

demands greater than four parts per million. This same dose of iodine

was found sufficient to reduce 106 enteric bacteria per ml to less than

5 per 100 ml within ten minutes and effective against leptospira,

schistosomes and viruses. They concluded that its germicidal action is

less dependent on pH, temperature, and time of contact than is that of

chlorine, and that nitrogenous impurities do not impair its effective-

ness, and side reactions leading to consumption of the germicide are

less marked for iodine than for chlorinous disinfectants.

In 1953, Morris, Chang, Fair, and Conant5 discussed water disin-

fection under field conditions. Their report included studies of

several iodine-releasing compounds. They concluded that any of the

iodine compounds discussed in this paper are suitable agents for the

emergency disinfection of water supplies when used in amounts sufficient

to yield eight parts per million of active iodine, and that the use of

one tablet containing approximately 20 mg of tetraglycine hydroperiodide,

90 mg of disodium dihydrogen pyrophosphate, and 5 mg of talc per quart

of water, is a convenient and reliable method for the emergency treat-

ment of drinking water supplies.

In a study by the military,25 Morgan and Karpen reported on the

toxicology of low concentrations of iodine consumed in drinking water

for extended periods under conditions of high humidity and temperature.

Their principal objective was to discover any toxic effects of iodine

consumed over a period of several months. They estimated that for the

first 16 Weeks of this study the average iodine intake per man per day

was 12 mg. During the last ten weeks the iodine concentration in the

- 14 -

water was increased to provide an average estimated dose of 19.2 mg per

man per day. The unique taste of the iodine treated water was first

objectionable to most of the personnel, but after a period of exposure,

only a few still found the taste unpalatable. The average values

derived from serial clinical tests over the six-month period were com-

pared with (a) conventionally accepted normal values, (b) average values

from subjects consuming only chlorine treated water, and (c) each other

to detect any significant pathologic trends. Symptoms, signs, and

laboratory findings indicative of disease were sought in individual


Analysis of all the data failed to reveal evidence of weight

loss, failure of vision, cardiovascular damage, altered thyroid activity,

anemia, bone marrow depression, or renal irritation among the personnel

consuming the iodinated water. In the opinion of the investigators,

consumption of the iodinated water over a six-month period did not

result in an unusual incidence of any form of skin disease. There was

no evidence of sensitization to iodine among the healthy station per-

sonnel under observation, nor was there any indication of impaired wound

healing or defective resolution of infections as a result of the con-

sumption of iodinated water.

Witlin and Gershenfeld26 tested iodine solutions against three

organisms at three different temperatures (50C, 20C, and 37?C). They

tested iodine solutions by two different techniques against the

organisms E. Coli, M. pyogenes (aureus) and S. typhosa, and concluded

that in both instances, iodine was more effective than chlorine with

- 15 -

all three test bacteria at all three temperatures.

In 1957, Carroll, lannarone, and Stonehill27 in a presentation

before the American Chemical Society discussed some of the chemical and

antimicrobial properties of iodine solutions. They found that hypo-

iodous acid was four to five times as effective as I, against M. pyogenes

(aureus) and three times as effective as I against E. coli (ATCC 9367).

They found that HOI was more effective at halogenating proteins than I1

and that HOI was a more effective protein denaturant than I,.

Lawrence, Carpenter, and Nayler-Foote28 studied iodophors and

reported that the particular iodophor they studied (Wescodyne) was

highly fungicidal, lethal to tubercle bacilli and effective against

spores of B. subtilis.

Bartlett and Schmidt29 reported on their study of surfactant-

iodine complexes as germicides. They found that exposure of 104 in-

fectious doses of virus to a dilution of bactericide containing 75

parts per million available iodine completely inactivated polio virus

within two minutes. They used types I, II, and III pathogenic polio.

In 1958, Chang0 set forth important considerations in water

disinfection with elemental iodine. He discussed the cysticidal and

viricidal efficiencies of various species of iodine and stated that at a

given temperature and a given concentration of E. hystolytica cysts,

the minimum cysticidal residual I is a function of contact time. He

showed that the viricidal residual I, and contact time were inversely

proportional. Equations were presented for computing the cysticidal

residual I, with a given contact time, and vice versa, at varying

- 16 -

temperatures, as well as others for computing the cysticidal residual

iodine in 12 I3- systems. He pointed out that efficient use of halo-

gens and active halogen compounds as water disinfectants demands a clear

understanding of their chemical reactions in dilute water solutions and

the relative germicidal efficiency of each species of active members

that may be formed in the solution. Since natural fresh waters rarely

contain enough iodine to interfere, given the pH, temperature, and

titrable iodine demand of the water, and the iodide content in the

preparation of elemental iodine, it is relatively simple with the infor-

mation presented to compute the dosage of the iodine preparation needed

to treat the water adequately for drinking purposes.

Gershenfeld and Witlin31 described studies concerned with the

rate of kill of iodine solutions, chlorine solutions and quaternaries.

Solutions of elemental iodine exhibited the most rapid rate of kill and

were superior to those chlorine solutions and quaternaries tested. In

general, iodine sanitizing solutions exhibited the same efficiency in

ten seconds as in one minute when using concentrations of more than ten

parts per million of free iodine.

Black, Lackey and Lackey were the first to use iodine to disin-

fect eight outdoor swimming pools. They reported iodine to be fully

effective in the disinfection of the water of the eight swimming pools

treated. It was not only equal to chlorine but in many cases superior.

They found that iodine residuals were much less dependent upon bather

load than chlorine residuals. This they felt, might be expected be-

cause iodine does not form substitution compounds with ammonia as does

- 17 -

chlorine. They found that no odors or tastes or irritations of the

eyes of bathers were produced by the iodine residuals employed during

the course of these studies, and no visible growths of algae were noted

during the testing period.

In 1959, Black, Boudet, and Giddens,32 in a second study, pre-

sented data on the use of iodine for swimming pool water disinfection

which confirmed earlier data. Iodine was found to be an effective

agent for the disinfection of swimming pool waters. They used four

swimming pools and found no iodate build-up in the pH range 7.2-7.5.

Iodine produced less change in pool pH than either chlorine or hypo-

chlorite, whether fed as iodine-iodide solution, aqueous iodine solu-

tion, or iodine released from pool iodide by chlorine feed.

In 1960, Marshall, McLaughlin and Carscallen7 reported their

findings after iodination of a cooperative pool. Ninety-six percent

of the tested samples conformed to drinking water standards. Due to a

decrease in eye irritation, and despite the noticeable color changes,

a majority of bathers (68.3%) preferred iodine-treated water to chlorine-

treated water. No difficulties were encountered in the operation of an

iodine disinfected pool with maintenance of free iodine in the range of

0.2 to 0.6 parts per million. The reactions of the operating personnel

were unanimously favorable for iodine disinfection.

In 1961, Marshall, Wolford and Faber33 reported the identity of

an organism comprising 99% of the colonies appearing on standard plates

in an iodine disinfected pool. They found that this organism was highly

resistant to both chlorine and iodine. They concluded that apparently

- 18 -

alcaligenes faecalis has no great significance in the sanitary analysis

of swimming pool water.

Black8 summarized the properties of iodine which appear most

attractive in swimming pool disinfection.

1. Use in a large number of swimming pools over extended

periods of time has demonstrated its effectiveness as a

germicide over a wide range of pH values.

2. It does not combine with ammonia to form iodoamines.

3. Its relatively low chemical activity makes it somewhat less

dependent upon bathing loads and organic matter present in

the water than other halogens.

4. Used in the form of HIO no color is produced in the pool


5. Odors and tastes are absent and irritation of the eyes of

bathers does not appear to result from its use.

In 1961, Kabler, Clarke, Berg, and Chang4 discussed the viricidal

efficiency of disinfectants in water. They reported that iodine was

an effective viricide, but required greater residuals and longer contact

than hypochlorous acid. A greater contact time was of more benefit than

increasing the concentration.

In 1962 it was reported35 that 0.3 to 0.5 parts per million of

both bromine and iodine inactivate at least six common enteroviruses,

parainfluenza-1 virus and enteric bacteria.

Cothran and Hatlan9 reported their results from iodine disinfec-

tion of an outdoor swimming pool. Their findings substantiated

- 19 -

previous findings. The pool required about 0.38 parts per million

iodine per day. During the entire study, only two 24-hour standard

plate counts were above 200 colonies per ml. Bathing load had little

effect on water quality. The swimmers preferred the iodinated water

because they had suffered eye burn the previous season when the pool

was chlorinated.

In 1962, the Public Health Service36 stated its position con-

cerning the use of iodine for swimming pool waters and concluded that

until more definitive information was available, iodine was an accept-

able disinfectant for use in swimming pool waters provided the maximum

concentration of iodine in all forms does not exceed five parts per


In 1963, Byrd, Malkin, Reed, and Wilson37 reported the results

of a study to determine the safety of iodine disinfection of swimming

pools. They found no change in blood protein-bound iodine or urinary

total iodine in 30 male subjects selected from three different swimming

pools. The subjects were tested at one day, one week, and one month.

They concluded that the use of iodine as a swimming pool disinfectant

was safe, effective, and superior to the use of chlorine in regard to

eye discomfort and irritation.

In 1964, Favero and Drake compared the bacteriology of five

swimming pools which were iodinated for a period of time and then

chlorinated for a like period. They found there were fewer staphylococci,

coliform bacteria, enterococci and streptococcus salivarius during the

iodination period, but total viable counts were significantly high.

- 20 -

Iodine-resistant pseudomonads, physiologically identical to the non-

pathogenic alcaligenes faecalis, were responsible for the high total

viable counts.

Lackey, Lackey and Morgan39 reported the algaecidal properties

of iodine. They tested 136 species and found that 0.2 parts per million

residual iodine gave good control, but not absolute kill, for in some

instances cultures developed after standing for several weeks.

In 1964, a patent was granted to F. J. Zsoldos, Jr.40 for a pro-

cedure for water treatment which utilizes chloramines plus hypoiodous

acid to maintain a continuous disinfecting agent in a swimming pool.

Berg, Chang, and Harris41 reported on studies of the devitaliza-

tion of microorganisms by iodine. They studied Poliovirus 1 (Lotshaw),

Coxsackievirus A9, and Echovirus 7 with iodine dosages varying from

4.6 parts per million to 38.2 at pH 6. By extrapolation from their

data, 99% devitalization of Coxsackie 49 virus required 1.27 parts per

million iodine with 40 minutes contact at 250C. Devitalization was

described as the loss of the ability of a virion to reproduce itself.

The validity of this extrapolation needs to be verified by actual


In 1965, Mills42 studied the bactericidal properties of the

halogens and reported that no sweeping general conclusions could be

made regarding the relative activities of chlorine, bromine, and

iodine. He found iodine more stable under ultraviolet light than

either chlorine or bromine, and stated that much of the published lit-

erature was in disagreement on the relative activity of chlorine and

21 -

iodine, but there was little question that due to the larger detri-

mental effects of ammonia, pH and sunlight, chlorine in most practical

cases was less effective. He concluded that physio-chemical factors

influence the biocidal activity of the halogens and that comparisons

of the biocidal activity of the halogens varied with the organisms

under each specific set of conditions, and that knowledge of the factors

influencing activity helped to determine the optimum conditions of dis-

infecting swimming pools.


In evaluating the effectiveness of any agent for the disinfec-

tion of water one must be familiar with all of the chemical reactions

it is likely to undergo under actual conditions of use which means, of

course, in very dilute aqueous solutions. For example, it has been

shown that hypochlorous acid, HOC1, formed by the reaction of chlorine

with water, is the most effective form of chlorine and that chloramines

formed by the reaction of chlorine or hypochlorous acid with ammonia

are much less effective3 These reactions are represented in equations

one through four.

C1 + HO H HOC1 + H+ + C- (1)

NH3 + HOC1 NHgC1 + H20 (2)

NHzC1 + HOC1 NHC12 + H20 (3)

NHC1, + HOC1 NC13 + HO0 (4)

To illustrate the importance of the species of germicide present

in dilute aqueous solution, Wattie and Butterfield have shown that the

ability of chloramines to destroy bacteria is far less than that of free

available chlorine. These investigators demonstrated that in chlorine-

free, chlorine demand-free water of pH 7.8 some E. coli survived after

120 minutes exposure to water containing 0.30 ppm of chloramine, and at

pH 8.5 some E. coli survived for 240 minutes at the same chloramine

concentration, namely, 0.30 ppm. In contrast, no E. coli survived after

five minutes exposure to water containing only 0.07 ppm of free chlorine.

- 22 -

- 23 -

The statement is commonly made that free chlorine is approximately 30

times as effective as chloramines in bactericidal efficiency.

Effect of pH

In addition, hypochlorite ion, OC1~, formed in increasing amounts

as pH increases, is relatively ineffective in water disinfection.

Equation (5) represents this equilibrium and Table 4, taken from the

classical paper of Wattie and Butterfield presents the percentage of

each species at different pH values.

HOC1 H H+ OC1- (5)

Table 4

Percent of Free Available Chlorine in the pH Range 4-10

pH Molecular Chlorine Hypochlorous Acid Hypochlorite Ion

4 0.5 99.5 0

5 0 99.5 0.5

6 0 96.5 3.5

7 0 72.5 27.5

8 0 21.5 78.5

9 0 1.0 99.0

10 0 0.1 99.9

In the case of iodine, five different factors and four different sub-

stances must be considered.

- 24 -

Hydrolysis of I,

I2 + H20 HIO + H + I- (6)

Una D [ Kh (7)

Kh = 3 x 10-13 at 25oC and 9 x 10-15 at OC.

Equation (6) represents the reaction of iodine with water to form hypo-

iodous acid, HIO, and the hydrolysis constant Kh is calculated from

equation (7). Its value is 3 x 10-13 at 25C. Chan30 has calculated

the effect of pH on this reaction for total iodine concentrations of

from 0.5 to 50.00 parts per million. Table 5, calculated from his data

for a total iodine residual of 0.5 parts per million, illustrates that

whereas at pH 5 about 99% is present as elemental iodine and only 1% as

hypoiodous acid, at pH 7 the two forms are present in almost equal con-

centrations, and at pH 8 only 12% is present as elemental iodine and 88%

as hypoiodous acid. Both of these species are effective germicidal agents.

Table 5

Percent of Ia Residual of 0.5 ppm Present

pH Ia Hypoiodous Acid, HIO Hypoiodite Ion, 10-

5 99 1 0

6 90 10 0

7 52 48 0

8 12 88 0.005

- 25 -

Effect of pH on Formation of Hypoiodite Ion

The second factor to be considered is the effect of pH on the

conversion of hypoiodous acid, HIO, to hypoiodite ion, 10.
HIO H+ + I10 (8)

SEo = K (9)

Ka = 4.5 x 10-13 at 25C.

[H] = Ka [ (10)

D =- M (11)
=o0 K a

Equation (9) is used to calculate the dissociation constant of hypo-

iodous acid, Ka, which is only 4.5 x 10-13 at 250C. In other words,

HIO is only very slightly stronger than pure water as an acid. With

equation (11) it is readily possible to calculate for any hydrogen ion

concentration and pH value the ratio of undissociated acid to hypo-
iodite ion. Equations (12) and (13) illustrate this for pH 8 and pH 9.
pH 8 at 250C.

rI 1x10-8 -2.2 x10 (12)
1-O- : 4.5 x 1l-13
pH 9 at 250C.

S 1 = 2.2 x 103 (13)
=IO- 4.5 x 10-13
So at pH 8 there are 22,000 undissociated HIO molecules to each hypo.
iodite ion, and at pH 9 the ratio of HIO to 10" is still 2200 to 1.

It is of interest to compare the effects of pH on chlorine and

iodine residuals. When Tables 4 and 5 are compared, it will be noted

- 26 -

that whereas at pH 8.0, 78.5% of a chlorine residual is present as

relatively ineffective hypochlorite ion and only 21.5% is present as

hypochlorous acid, at the same pH, 88% of the corresponding iodine

residual is present as hypoiodous acid, 12% as diatomic iodine, both

effective germicides, and only 0.005% or an unmeasurable trace is

present as hypoiodite ion. This is an important advantage of iodine

over chlorine for water disinfection at high pH values.

Formation of Tri-iodide Ion, 3I

The third factor is the possibility of the formation of bacteri-

cidally ineffective tri-iodide ion, 13'. Equation (14) represents this


2 + 1 13- (14)

N = Ki (15)

Ki = 1.4 x 10-3 at 25C and 0.7 x 10-3 at OOC.

Chang30 investigated this reaction and has calculated that the forma-

tion of the tri-iodide ion will not be significant or even measurable

at the low concentrations of 12 and I" which would be present in water

disinfected with iodine.

Formation of Iodate Ion

The fourth factor is the conversion of hypoiodus acid to iodate

ion at high pH values, according to the following reaction.

3HIO + 2(OH-) 0 HIO0 + 2H20 + 21" (16)

- 27 -

It has been shown that iodate ion possesses no disinfecting

ability. Chang0 found that an iodate solution capable of liberating

10,000 parts per million of titrable iodine in the presence of an acid

and iodide exhibited no cysticidal effect at pH 7.0 and 250C even after

four hours contact time. Any substantial formation of iodate would, to

the extent that it is formed, lower the disinfecting ability of the

dosage of iodine added. Wyss and Strandskov studied this reaction in

carbonate, borate and phosphate buffers and found that at high pH values

this reaction proceeds rapidly. According to their data the decompo-

sition rate in a solution containing 30 parts per million or less

titrable iodine is slow at pH 8.0 maintained by a borate or carbonate

buffer, whereas in the presence of a phosphate buffer, two-thirds of

the HIO has been converted to iodate in 40 minutes. At pH 9.0 the rate

of decomposition was found by them to be so rapid that in ten minutes

about two-thirds, three-fourths and five-sixths of the HIO was converted

to iodate in berate, carbonate, and phosphate buffer, respectively.

However, their work was done employing concentrations of hypoiodous acid

and iodine, HIO and I2, in relatively high concentration, many times

greater than would be encountered in water disinfection practice. Data

to be presented in this study show conclusively that such reversion

does not take place in the buffers used by them when concentrations of

I, and HIO used in water treatment practices are employed.

No Reaction with Ammonia

The fifth factor to be considered is the question whether I2 or

28 -

HIO will combine with ammonia or ammonia derivatives in water to form

iodoamines. Strong solutions of iodine and ammonia will combine to form

the very explosive compound NI3, but in the dilute aqueous solutions used

in water disinfection practice there is no reaction between iodine and

ammonia. McAlpine45 gives evidence that a colorless iodoamine is found

according to the following reaction.

I2 + 2NH3 NH2I + NH,+ + I (17)

K = about 2

He bases the validity of this reaction on the decolorization which takes

place when 50 ml of 0.01 N KI3 solution was added to 200 ml of 0.01 N

NH3. Data to be presented in this study show that the possibility of

iodoamine formation in dilute aqueous solution is extremely remote when

concentrations of iodine which are used in water disinfection are used.


Based on the data obtained in previous studies, it was felt that

the time had come to evaluate the effectiveness of iodine as a water

disinfectant in broad perspective, and this study was therefore planned

to demonstrate its effectiveness for the disinfection of public water

supplies and to determine the physiological effects on a human popula-

tion. In order to demonstrate these parameters and many others, a

captive population of approximately 800 individuals consisting of white

adult males and females and Negro women and girls was selected, and the

water supplies involved were iodinated. The data presented in this

study have been accumulated over a period of more than two years and

actual iodination has been continuously carried out since October, 1963.

Iodine Disinfection at Lowell, Florida

Description of Water Systems

Station No. 1 Three institutions at Lowell, Florida, were

selected as the site of this investigation because they duplicate insti-

tutional and municipal water systems and because their populations are

maintained under controlled environmental conditions where they are

available for physiological testing. Station No. 1 is the larger of the

two water systems being used for this study and supplies the Florida

Correctional Institution for Women, a maximum security prison, and the

Forest Hill School for Girls, a school for delinquent iegro girls,

- 29 -

- 30 -

located on adjoining tracts at Lowell, Florida, about 27 miles distant

from the University of Florida campus. Figures 1 and 2 are aerial photo-

graphs of the Women's prison and the School for Girls. Figures 3, 4 and

5 are schematics of all three institutions. This water system consists

of two four-inch diameter wells approximately 150 feet deep, a 75,000

gallon covered ground storage reservoir, a high service pump station

containing two 60 gallon per minute centrifugal pumps and one 500 gallon

per minute fire service pump, and a 75,000 gallon elevated storage tank

which floats on the distribution system. The pump house contains

additional metering and chemical feeding equipment plus gasoline engines

for stand by power. The daily demand of this system ranges between

70,000 gallons per day and 100,000 gallons per day, and it serves approx-

imately 500 individuals, including inmates of the two institutions,

administrative staff and civilian employees. Each institution has its

own laundry facility. Figure 6 illustrates the original equipment in

Station No. 1. Figure 7 presents the monthly water consumption at

Station No. 1 for the period of this study through August, 1965.

Station No. 2 This station is the smaller of the two and

supplies a men's medium security prison located about one mile distant

from the others. It has one six-inch diameter well, a 4,000 gallon

hydropneumatic tank, and a pump house containing high service metering

and chemical feeding equipment. The daily demand of the smaller system

ranges between 20,000-30,000 gallons per day and it serves approximately

180 inmates, administrative staff and civilian employees. Figure 8

shows the original equipment of Station No. 2. Figure 9 contains the

- 31 -

Fig. 1 Aerial Photograph of the Florida Correctional Institution
for Women.

Fig. 2 Aerial Photograph of the Forest Hill School for Girls.

- 32 -



O a
0 .

ago V \
S0 0

>- c


(o Co
SC\ j O)

3 b Lp







o __
"--- -{--)

0 E a
- 0






- 33 -




- 34 -

E 'w
L 0

fO 1 0

lo Z


I ( ^0 a

0 I _. U

_L .__s

- 35 -

Ground Storage

No.1 Pump-60gpm.

No.2 Pump-60gpm.

Disc-Type Meter

Elevated Storage

Distribution System

Women's Prison&Girls' School

- 36 -





















N 0 CO \0 N 0 CO
UCt Cr' C e JN O o rH


- 37 -

Distribution System

Pneumatic Tank-4000gal.

3 Gate Valves
Check Valve

Well & Pump-200gpm.
On-30 Off-60psi.

Men's Prison

- 38 -


K// nr \


-o Q
0 1400 4),

deI I0' )

u' +0 U

T----7- y/ '^N ^ g

Guon^co JO Suo-TmIw

- 39 -

monthly water consumption data for this station for the period of the

study through August, 1965. Table 6 contains the water consumption

data for both stations for the entire period of the study. Prior to

the initiation of this study, the water in both systems was being dis-

infected with calcium hypochlorite.

Chemical Characteristics of the Well Waters

The chemical characteristics of the water obtained from all three

wells are typical of wells penetrating the limestone aquifer which under-

lie practically all of Florida. Individual chemical analysis of the

three wells are shown in Table 7, and the results of the spectrographic

determination of the concentration ranges of eight trace elements are

shown in Table 8. A ten liter sample was evaporated to dryness for the

trace analyses. The analyses indicate that the water is moderately hard,

very low in iron and free from hydrogen sulfide. The organic content of

the water is low and, as will be shown later, the bacteriological quality

of water from Wells No. 1 and No. 2 has been found to be poor throughout

the entire investigation, whereas the raw water from Well No. 3 meets

the bacteriological criteria of the 1962 DRINKING WATER STANDARDS.46

Coliform organisms have been present in more than 50% of samples col-

lected from Well No. 2, and in about 30% of those from Well No. 1. It

is unusual to characterize the presence of enteric organisms in a

water supply as fortunate, but in this case it is fortuitous since it

eliminates the necessity of adding some indicator organism or organisms

to the water before disinfection.

- 40 -

Table 6

Lowell Water Consumption Data
May 1963 to September 1965

Station 1 Station 2
Month Water Consumption (Gal.) Water Consumption (Gal.)

May 1963 3,117,740
June 2,525,940
July 3,148,670
August 2,710,000
September 2,620,000 666,000
October 2,714,000 730,800
November 2,393,140 736,800
December 2,622,120 729,600

January 1964 2,508,860 740,400
February 2,260,320 732,000
March 2,182,560 852,000
April 2,374,730 806,400
May 2,642,190 844,800
June 2,745,950 820,800
July 2,319,840 760,800
August 2,154,100 771,600
September 2,057,730 537,600
October 1,894,750 615,600
November 2,249,780 709,200
December 2,152,600 574,800

January 1965 2,011,940 589,200
February 1,856,870 553,200
March 1,909,960 613,200
April 2,418,570 662,400
May 2,963,020 950,400
June 2,377,190 669,600
July 2,377,920 720,000
August 2,423,960 819,600

Total water iodinated through August, 1965 65,971,300 gallons.
Total for Station 1 50,898,100 gallons.
Total for Station 2 15,073,200 gallons.
Average daily consumption at Station 1 78,000 gallons.
Average daily consumption at Station 2 23,200 gallons.

- 41 -

Table 7

Chemical Analyses of Water from Individual Wells

Parts per million
Constituent Well No. 1 Well No. 2 Well No. 3

Total dissolved solids

Silica, SiO,

Iron, Fe

Calcium, Ca+

Magnesium, Mg+

Sodium and potassium, as Na

Bicarbonate Ion, HCO3"

Sulfate Ion, SO,

Chloride Ion, Cl"

Nitrate Ion, N03"

Fluoride Ion, F"

Temp C















4.5 5.2

12. 11.

0.61 0.55

0.20 0.10

21.5 21.5

7.4 7.4














- 42 -

Table 8

Trace Elements in Water from Well No. 1

Element Concentration Range, ppb

Boron, B 2.3 23

Chromium, Cr 23 230

Copper, Cu 23 230

Manganese, Mn 23 230

Nickel, Ni 2.3 23

Strontium, Sr 23 230

Titanium, Ti 23 230

Silver, Ag 0.23 2.3

Iodination Procedure

Considerable renovation was necessary at Station No. 1 before

iodination could begin. A new roof, a sump pump, new doors and an

adequate drainage system were installed prior to iodination. Softening

equipment and a compressor were removed from the pump house to allow

space for the iodination equipment. The old disc-type meter was

returned to the factory for overhaul and new impellors were installed

in the pumps. New float switches were installed for the elevated tank

so that the system would be completely automatic. Figures 10 and 11

show the station in its original condition and following its renovation.

Station No. 2 required some piping changes and a new air relief valve

- 43 -

and check valve, but since the Station is relatively new, less renova-

tion was necessary here than at Station No. 1.

The Feeding of Elemental Iodine to Water

In this study iodine is being fed as the element in saturated

aqueous solution, although in practice it may also be added in the form

of a soluble iodide and then oxidized to the element by the addition of

an appropriate oxidizing agent. This point will be referred to again

in the laboratory studies section. The continuous accurate feed of

iodine in the two water systems has been found to be remarkably simple.

Although iodine is less soluble in water than any of the other halogens,

its solubility is appreciable and is significantly temperature depend-

ent. Figure 12 illustrates the change in concentration of a saturated

aqueous solution from 0C to 600C in the absence of added iodide ion.

The ground water has a temperature of 21.5 C which remains practically

constant throughout the year. It was only necessary to equip the pump

station with a heat pump so adjusted as to maintain the temperature

within the station at 21.50C to continuously produce a saturated iodine

solution with a constant concentration of 305 parts per million. Satur-

ation is achieved by passing some of the raw well water through a bed

of elemental iodine crystals of sufficient depth for saturation to take

place in what is called an iodine saturator. Figure 13 is a schematic

of the iodine feed apparatus.

A cross section of the simple saturator employed at Station No. 1

for 22 months is shown in Figure 14. It is constructed of a five foot

section of vitrified clay pipe with a reinforced concrete plug at the

Fig. 10 Station No. 1 at the Beginning of the Project.

Fig. 11 Station No. 1 with lodination Equipment Installed.


- 45 -








0 Oa CO C'- \ n C O H

ja0-T .id sura T

- 46 -

Feed Water

Solenoid Valve

Pressure Regulating Valve

Overflow Valve

Constant Level Device

Iodine Saturator

Metering Pump

Aqueous Metered to Raw
Iodine 300ppm Water Flow


- 47 -

,........ Plywood Cover
"-Saran Shield
1I.D.S.S. T-304
.-1O"x 5'V.C. Pipe
24" Elemental Iodine

2 1.5" 4mm. Glass
S Beads
S 6mm. Glass Beads
9"Glass Marbles
I.D. S.S. T-304
Paraffin Seal+Epoxy
Glass Plate
Reinforced Concrete

Station 1

bottom. Above the plug is a one-fourth inch glass plate, a nine inch

column of glass marbles, a one inch layer of six millimeter glass beads,

a 1.5 inch layer of four millimeter glass beads, and 24 inches of tech-

nical grade elemental iodine crystals. Water passes through a small

constant level tank mounted on the side of the saturator into the

saturator about two inches below the top and downward through the bed

of iodine crystals. A stainless steel pipe passing through the pipe

wall into the glass marble section at the bottom of the saturator

carries the saturated iodine solution to the metering pumps. The

capacity of the pipe section is such that it is not necessary to employ

additional storage for saturated iodine solution. The descending

column of fresh water above the bed of crystals prevents the escape of

any iodine vapor and the only cover provided for the saturator is a

thin sheet of Saran and a plywood square to hold it in place. The

addition of iodine to the saturator consists simply of removing the ply-

wood cover and pouring the iodine crystals into the saturator. The

saturated iodine solution is pumped from the saturator and metered very

accurately against the raw water flow by means of stainless steel posi-

tive displacement metering pumps. Each of the stainless steel metering

pumps is electrically interconnected to one of the high service pumps,

and complete automation is provided by differential pressure gauges

operated from the water level in the elevated storage tank. All pipe

carrying saturated iodine solution is stainless steel or equivalent.

Figure 15 is a photograph of the upper part of the saturator showing

the constant level cylinder, needle valve and solenoid valve for

- 49 -

automatic operation, and Figure 16 shows the lower part of the satura-

tor and the stainless steel lines carrying the iodine solution to and

from the metering pumps.

Figure 17 is a schematic diagram of all the equipment and instru-

mentation at Station No. 1, and Figure 18 is a schematic diagram of the

equipment at Station No. 2. With this equipment it has been possible

to continuously feed saturated iodine solution to provide any desired

dosage of iodine with an overall accuracy of I 0.05 parts per million.

During the 22 months which have elapsed since iodination was begun, and

during which 65 million gallons of water have been iodinated, only two

brief interruptions have occurred. Both of these interruptions of ser-

vice were due to electrical failure of the solenoid valve because of

overload and consequently the saturator could not make any iodine solu-

tion without water. Figure 19 shows the interior of Station No. 1 and

Figure 20 is an aerial photograph of the Male Unit.

Chemical Control

Desired iodine residuals are monitored with a continuous iodine

analyzer-recorder located inside the pump station and supplied with

iodinated water from the high-service discharge line one minute after

iodine injection. A second portable iodine analyzer-recorder is moved

from place to place in the system and a continuous record of iodine

residuals secured. During the first five months of iodination daily

charts were used in both instruments. As soon as the overall accuracy

of feeding had been established, both were adapted for the use of

weekly charts. Figure 21 shows a typical daily chart, and Figure 22

- 50 -

Fig. 15 The Upper Portion of the Iodine Saturator in Station No. 1.

Fig. 16 The Lower Portion of the Iodine Saturator in Station No. 1
with Adjacent Chemical Metering Pumps.

- 51 -

Ground Storage
Iodine Saturator
No.1 Pump-6Ogpm.
No.1 Metering Pump
No.2 Pump-6Ogpm.
No.2 Metering Pump
Recording Meter
Iodine Residual Recorder
Elevated Storage

Distribution System

Portable Iodine Residual

Women's Prison&Girls' School

52 -
Distribution System

SIodine Residual Recorder

Pneumatic Tank

SMetering & Mixing
L Loop
3 Gate Valves
Recording Meter
Iodine Saturator
Old Check Valve
Metering Pump
New Check Valve



- 53 -

Fig. 19 Interior of Station No. i.

Fig. 19 Interior of Station No. 1.

Fig. 20 Aerial Photograph of Male Unit.

- ~~P(3

Fig. 21 Typical Daily Chart from the Iodine Residual Recorder nhich
Monitors the Iodine Feed.

- 55 -

Fig. 22 Typical Weekly Chart from the Iodine Residual Recorder Which
Monitors the Iodine Feed.

- 56 -

a typical weekly chart, both from the instrument recording iodine feed,

and Figure 23 shows a typical chart from the instrument recording iodine

residuals in the distribution system. These analyzer-recorders are

Wallace and Tiernan Series A-767 Amperometric Residual Recorders.

These recorders are calibrated at two-week intervals with the Wallace

and Tiernan Amperometric Titrator, which will be discussed in the

laboratory study section. In addition to the continuous monitoring

of iodine feed and distribution system residuals by these analyzer-

recorders, other distribution system samples were taken and analyzed

by amperometric titration and by means of an iodine test kit developed

by Whittle.47 This test kit will be described later. Table 9 presents

typical iodine residuals at the ends of the distribution system for

the indicated iodine dosages. This table shows that a substantial

saving in iodine can be realized if only the necessary dose for adequate

bacteriology is maintained.

Products of Wallace and Tiernan, Belleville, New Jersey.

- 57 -

Fig. 23 Typical Distribution System Weekly Chart from Iodine Residual
Recorder. The Iodine Feed at this Time was 0.40 Parts Per

58 -

Table 9

Iodine Residuals at Ends of the Two Water Systems for
Indicated Iodine Dosages

Iodine Fed Range of Values for Average Residual System Demand
ppm Ia Residuals ppm ppm

Larger system serving women and girls

1.00 0.40 0.60 0.55 0.45

0.80 0.40 0.55 0.50 0.30

0.60 0.38 0.43 0.40 0.20

0.40 0.28 0.33 0.30 0.10

0.30 0.13 0.19 0.17 0.13

Smaller system serving men's prison

1.00 0.60 0.80 0.75 0.25

- 59 -

Iodine Feed at Lowell

Disinfection of water with elemental iodine was begun in the

system serving the Florida Correctional Institution for Women and the

Forest Hill School for Girls at 2:30 PM on October 28, 1963, using an

initial dosage of 1.0 parts per million of elemental iodine. On July 1,

1964, after eight months at this dosage level, it was supplemented by

the addition of potassium iodide equivalent to 4.0 parts per million of

iodide ion, to comprise a total dosage of 5.0 parts per million of

elemental iodine plus iodide ion. The iodide was fed by means of hypo-

chlorinators. This was continued for 64 days following which the feed

of KI was discontinued. Feeding of elemental iodine was continued at

the level of 1.0 parts per million until September 16, 1964, at which

time a planned program of gradual reduction in dosage was begun. This

gradual reduction was continued in step-wise fashion to 0.30 t 0.05

parts per million. This reduction in feed was carried out to determine

the lowest iodine dosage for adequate bacteriology. The bacteriological

results from this reduction in dosage will be presented later. The

reason for the addition of the iodide was to see what effect, if any,

this increased intake of the element would have on the human body.

These physiological results will be described later.

Iodination was begun in the system serving the Florida Correc-

tional Institution (Male Unit) at 9:00 PM on November 18, 1963, using

the same dosage of 1.0 parts per million of elemental iodine. On July 3,

1964, this dosage was supplemented with 4.0 parts per million iodide as

potassium iodide. After two months at this dosage, iodide feed was

- 60 -

discontinued and a dosage of 1.0 parts per million elemental iodine

has been fed continuously since that time.

The dosagesof iodine fed from October, 1963 through June, 1965

are shown in Figure 24.

Bacteriological Control

At the beginning of the study a routine sampling program was

initiated which involved collecting samples for bacteriological analysis

from all three wells and all three distribution systems twice each week.

Ten samples were collected by the author each week for bacteriological

analysis at the Earle B. Phelps Sanitary Engineering Research Laboratory

of the University of Florida. Another set of ten samples was collected

each week by the Marion County Health Department. Initially, these

samples were shipped to Jacksonville and analyzed by the Florida State

Board of Health. With the completion of a new bacteriological labora-

tory in the Marion County Health Department, located only seven miles

from the institutions, collection and analysis of these samples was

taken over by that laboratory. They determined the most probable num-

ber of organisms of the coliform group by the membrane filter technique

and reported the non-coliform organisms as heavy, medium or light.

The Earle B. Phelps Sanitary Engineering Research Laboratory determined

the most probable number of organisms of the coliform group by both

multiple tube and membrane filter techniques and, in addition, 24 hour

standard plate counts at 35 C on all samples.

- 61 -











0 0 0 upo
uxdd ouTpoI














- 62 -

Bacteriology During the Chlorination Period

As has been stated earlier, water from two of the three wells

used in this study frequently indicated the presence of coliform

organisms, Well No. 1 30% of the time and Well No. 2 more than 50% of

the time. Figures 25 and 26 show the results of the bacteriological

examination of ten weekly samples by the Florida State Board of Health

during the eight month period when calcium hypochlorite was employed.

As expected, results obtained with the membrane filter technique show

a lower percentage of unsatisfactory samples than results obtained by

the multiple tube technique. On the basis of the data shown in Figure

25, water in the distribution systems met the criteria of the 1962

DRINKING WATER STANDARDS.46 Figure 26 presents the data for non-

coliform organisms during the same period. The samples from the system

served by Station No. 1 had heavy growths of non-coliform organisms

about 15% of the time, while the samples from the system served by

Station No. 2 had heavy growths of non-coliform organisms about 10% of

the time.

Figure 27 presents the data for coliform organisms for the same

chlorination period obtained by the Earle B. Phelps Sanitary Engineering

Research Laboratory by the multiple tube technique. On the basis of

these data, only the water in the system served by Station No. 2 met

the 1962 DRINKING WATER STANDARDS,46 but water from Well No. 3, which

supplies this system, meets these criteria without disinfection.

Figure 28 presents the data for the standard plate counts per

milliliter at 350C during the chlorination period in the distribution

- 63 -

co 0 '(

26 2
p c ^

H; H -

4- 0 0

l 0p 4-
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H 0

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ciH 0
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co c- ^O C- \ U ( H 0V

eldwuS 4L00ovjsT00sun queojGj

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co c- 0o U- _. c% N r--i

sTldumres T01 JO ue0OJed

- 65 -





\o W77a,777777,
0 H\)
VJ~~7~ 7JY 7j.'J 77j

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00 V'% 4t~

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seodureS CioqoLjsvgeutn 4uao0.eo




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- 66 -

-P rto
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44 +4 .4 tt
+400 0 0 z
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r( I V re cc 0

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+4 0
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Wr a) G C
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0 0 0 0 0 0 0 T
O t^ v0 ^ ^t f^ ) rl fr

seTduzreg T'oJ Jo quaojej


- 67 -

systems. Of the 250 total samples, 64.6% were in the range 0-20

colonies per milliliter and 5.2% of the samples contained more than 200

colonies per milliliter.

It should be emphasized at this point that throughout the chlor-

ination phase of this study, the water systems were still under oper-

ational control of the respective institutional staffs even though

iodination equipment was being installed. The operators of both systems

were not adequately trained and did not always have sufficient chlorine

in the systems. This is apparent from the bacteriology and from the

chlorine residuals found in the system by the author. Table 10 presents

some of these data. Many times there were only trace quantities of

chlorine or none at all in both systems. At other times there was as

much as 2.0 parts per million free chlorine in the system. The opera-

tors did not determine chlorine residuals, but simply added a gallon of

the hypochlorite solution to the solution tank of the hypochlorinator

and fed the mixture. At times it would pump dry and at other times the

discharge lines or suction lines for the pumps were clogged and no

chlorine was being pumped. Frequently, much of the chlorine had vola-

tilized from the stock solution before it could be used. The disinfec-

tion procedure as practiced here was less than adequate.

Bacteriology During Twenty-Two Months of Iodination

Iodination was begun on October 28, 1963, and Figures 29 and 30

present graphical analyses of bacteriological data obtained by the

Florida State Board of Health during the 22 month period which has

elapsed. Figure 29 presents the data for organisms of the coliform

- 68 -

Table 10

Typical Free Chlorine Residuals in Parts Per Milljon
in the Distribution Systems Prior to lodination

Girls School Women's Prison Men's Prison

0.05 .05 o 0 0.05 0.10 0 0 0.10

0 .05 0 0.05 0.05 0.14 o 0.05 0.15

0 .05 0 00.05 .05 0.10 0.05 0.05 0.15

0 .05 0.15 0.05 0.05 0.15 0.05 0.05 0.10

0.05 .05 0.18 0.05 0.05 1.50 0.05 0.05 0.10

0 .05 0.18 0.05 0.05 1.50 0.05 0.05 0.15

o .05 0.10 0.05 0.05 o 0.05 0.05 o.10

0 .05 0.10 0.05 o 0.05 0.05 o 0.30

0 .05 0.10 0.05 0 0.25 0.05 0 0.20

0 .05 0.05 0.05 0 0.13 0.05 0 0.20

0.05 .05 0.10 0.05 o 0.05 0.05 o 0.30

0.05 .05 0.10 0.05 0.10 0 0.05 0.05 0.10

1.0 .05 0.14 0.05 0.10 0.25 0.05 0.05 0.15

.05 0 2.0 0.05 0.10 0.30 0.05 0.10 0.10

Each value represents a different day during an overall period
of approximately eight months. Samples were collected at different
points in the distribution system.

- 69 -

~~ H


v :


0 0












a. .

i-l u^

0 0)
T l



0 0 0 0 0 0 0
Co r- \0 Co CN

SledureoS hlo0)jSssun ueojel





- 70 -




eIdumnS [Biol queojed







0 (1)




- 71 -

group. These data show a dramatic decrease in the number of unsatis-

factory samples after disinfection with iodine. Percentages of unsatis-

factory samples of 51.5% and 67.5% for Wells No. 1 and No. 2 respectively,

drop to 5.5% for the Women's system and 4.9% for the Girl's system. The

8.2% unsatisfactory samples from Well No. 3 is reduced to 3.5% in the

system. Figure 30 presents the non-coliform data for the iodination

period. These data show a marked decrease in the number of non-coliform

organisms after iodination. These data, accumulated by the Florida

State Board of Health and totaling 544 samples, show that the water in

the distribution systems far exceeds the criteria of the 1962 DRINKING


Figure 31 presents the data using multiple tuble techniques for

coliform organisms from 787 samples, obtained by the Earle B. Phelps

Sanitary Engineering Research Laboratory. The percentages of unsatis-

factory samples from Wells No. 1 and No. 2, 37.5% and 67.1% respectively,

were drastically reduced to zero in the Women's prison and to 1% in the

Girl's school. Well No. 3 had 8.3% unsatisfactory samples, which was

reduced to 0.6% in the distribution system of the male unit. These are

substantial reductions and demonstrate the remarkable effectiveness of

iodine in routine water disinfection. Standard plate count data are

shown in Figure 32 for these same distribution system samples. About

80% are in the range 0-20 colonies per milliliter and 90.0% are below

50 colonies per milliliter. Only 2.9% of the 560 total distribution

samples had plate counts above 200 colonies per milliliter. These data

further substantiate the effectiveness of iodine as a water disinfectant.

- 72 -





H r-I



o o

0 0)

cq 0

0 0)

0 0

0 *



CM a
0 0





Hi 1-4
0 ~r(D

a ^^

CQ co z







0 0 0 0 0 0 0
\0 0- (-t '- N H

seEduorG Al.OoJ0),)e0sun U uefol e

H "A

- 73 -

a,(/ 0





r(U C^



II =

-0 (M

43 0


c^ k

C 01






0. 0



i )




0 0 0 0 0 0 0 0 0
o rC- NO N r -

eoldurem g pno. Jo .uo.ieJd



- 74 -

The iodine dosage was 0.30 0.05 parts per million during the collec-

tion of 72 of these 560 samples, hence, even this low dosage of

elemental iodine proved to be highly effective.

The group of samples designated "station discharge" requires a

word of explanation. Iodine solution was added to the water in the dis-

charge header inside the pump station and these samples were collected

just outside the station from the discharge line carrying iodinated

water to the elevated tank. The contact time of the iodine with the

water before its removal by the thiosulfate in the sample bottle was

less than two seconds. In spite of this momentary contact time, the

data in Figures 29 and 31 show that it was sufficient to reduce the

number of unsatisfactory samples from Well No. 2 by about. 50.

Special Distribution System Bacteriological Study

This reduction in bacteria after only a brief contact time of

two seconds was intriguing. Three experiments were run at the station

discharge to study the effect of the short contact time of the iodine

with the water on bacterial kill. Tables 11, 12, and 13 present these

data. In all three experiments, after 15 seconds contact time of the

iodine with water, there was considerable reduction in the MPN values

and the standard plate counts. In two of the experiments the coliform

density was reduced to satisfactory levels after only 45 seconds, and

after one minute the coliform densities were reduced to satisfactory

levels in all samples. These data represent actual distribution system

conditions at the station discharge at Station No. 1 at Lowell.

- 75 -

Table 11

Typical Study Showing the Effect of Contact Time on
Bacterial Kill, May 3, 1965

I, = 0.30 ppm Temperature = 22.50C pH = 7.4

MPN/100 ml MPN/100 ml Standard 24 hour
Contact Time Multiple tube Membrane filter Plate Count at 35C

2 seconds 13 5 28

15 seconds 2 <1 9

30 seconds 5 <1 1

45 seconds 2 <1 14

1 minute <2 <1 5

5 minutes <2 <1 8

10 minutes <2 <1 8

15 minutes <2 <1 10

20 minutes <2 <1 5

25 minutes <2 <1 9

30 minutes <2 <1 11

- 76 -

Table 12

Typical Study Showing the Effect of Contact Time on
Bacterial Kill, May 10, 1965

12 = 0.30 ppm Temperature = 22.50C pH = 7.4

MPN/100 ml MPN/100 ml Standard 24 hour
Contact Time I -tiple Tube Membrane Filter Plate Count at 35 C

2 seconds 49. 1 21

15 seconds <2.0 <1 22

30 seconds <2.0 < 1 7

45 seconds <2.0 < 1 9

1 minute <2.0 <1 7

5 minutes <2.0 <1 13

10 minutes <2.0 <1 10

15 minutes <2.0 1 7

20 minutes <2.0 <1 13

25 minutes <2.0 <1 13

30 minutes <2.0 <1 23

- 77 -

Table 13

Typical Study Showing the Effect of Contact Time on
Bacterial Kill, May 17, 1965

Iz = 0.30 ppm Temperature = 22.50C pH = 7.4

MPN/100 ml MPN/100 ml Standard 24 hour
Contact Time Multiple Tube Membrane Filter Plate Count at 350C

2 seconds 49 26 47

15 seconds 22 1 9

30 seconds 8 1 11

45 seconds < 2.0
1 minute < 2.0 1 14

5 minutes <2.0 <1 10

10 minutes < 2.0 <1 5

15 minutes < 2.0 <1 20

20 minutes 2.0 <1 13

25 minutes <2.0 <1 11

30 minutes < 2.0 1 11

- 78 -

Physiological Control

The medical aspects of this study were under the direction of

Dr. W. C. Thomas, Jr., Professor of Medicine in the J. Hillis Miller

Health Center, University of Florida. He was assisted by Dr. Gerhard

Freund and Dr. E. D. Bird, both Assistant Professors in the Department

of Medicine. The dosages of iodine used for disinfection and those in

excess of the amount required for disinfection were agreed upon after

consultation with Dr. Thomas and his staff.

Medical Assessment and Selection of the Sample Population

Each fifth inmate of the prison community was selected for care-

ful evaluation as to the effect of the iodinated water supply on the

health and thyroid function of exposed individuals. Prior to and during

the period when ingesting iodinated water, these test subjects were

examined for evidence of rash or change in size or consistency of the

thyroid gland. Additional procedures consisted of serial hematocrit

determinations, white blood cell and differential blood counts, and

determinations of radioactive iodine uptake by the thyroid gland (RAI),

protein bound iodine (PBI) and serum thyroxine (T,). The physical

examinations and RAI determinations were made at the prison by Dr.

Thomas and members of his staff, while the PBI and T4 determinations

were performed by the Bio-Science Laboratories, Los Angeles, California.

Physiological Response to Iodine Intake

During the period of medical evaluation, discharge of some of

the prisoners resulted in gradual attrition in the number of test sub-

jects selected initially. One hundred and twenty-five inmates were

- 79 -

evaluated twice, and eight inmates only once, prior to iodination of the

water supply. Seventy of the prisoners were available for examination

during the entire study period. Although at the outset the test group

was divided almost equally into adult males, adult females and 13 to 16

year old Negro girls, losses from the group during the study were

largely among the adult males and teen-age girls.

Figure 33 shows the effect of iodine ingestion on radioactive

iodine uptake (RAI). Values plotted are the mean values for the group

plus or minus one standard deviation. After 30 days use of iodinated

water the mean value for RAI had decreased from about 17% to about 7%.

Values determined at the end of three months and of seven months of

feeding 1.0 parts per million of iodine showed little further change.

However, increasing the dosage to a total of 5.0 parts per million

iodine plus iodide for 60 days decreased the mean RAI to about 2%.

Figure 34, plotted on the same time scale, shows the changes in

mean values for protein bound iodine (PBI) during the ten month period.

There was a slight increase at the end of the first month of iodine

feed, a further slight increase at the end of the third month, no

further increase at the end of the seventh month, and a small but

definite increase at the end of the tenth month following 60 days of

feeding 5.0 parts per million of iodine plus iodide. It is to be noted,

however, that until the iodide content of water was increased to 5.0

parts per million the mean PBI values were well within the normal range

of 4-8 Pg/100 ml.

Figure 35, plotted on the same time scale, shows clearly that

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there was no significant change in the mean values for the concentration

of thyroxine in sera during the entire ten month test period.

A study of urinary iodide excretion was made later in the program

when the iodine dosage had been reduced to 0.60 parts per million.

Figure 36 presents these data. It was found that the urinary iodide

was more than 500 micrograms per gram of creatinine excreted in each

of the 50 inmates studied, thus confirming the usefulness of this ratio

in estimating iodine intake.

During the entire test period and during the many months of con-

tinuous iodination which have followed, there has been no evidence of

allergic reactions to iodine or any change in the size of the thyroid

gland. To date there is no evidence that iodine, under the experimental

conditions employed, has had any detrimental effect on general health or

thyroid function either when ingested in drinking water or, as will be

shown later, on individuals exposed to swimming pool water disinfected

with iodine.

Aesthetic Considerations

A number of interested scientists have visited the institutions

and each has been requested to attempt to identify any tastes or odors

which may be present in the water. These people represent eleven dif-

ferent foreign countries and thirteen different states of the United

States. In addition, several test panels have been conducted using

graduate students as highly qualified participants. These laboratory

data will be presented in the laboratory studies section. The insti-

tutional personnel and inmates have volunteered comments from time to

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