COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS
STATE OF FLORIDA
COLLEGE OF AGRICULTURE. AGRICULTURAL EXTENSION SERVICE
UNIVERSITY or FLORIDA, AND Vegetable Crop Specialists COUNTY AGENT AND
UNITED STATES DEPARTMENT OF HOME DEMONSTRATION WORK
AGRICULTURE. COOPERATING V E G E T A R IA N GAINESVILLE, FLORIDA
University of Florida
January 28, 1960
By this time most of you have had your feet to the fire one way or another over
the Food and Drug Administration activities AC (after cranberries). Many of you
have asked about ways to remove pesticide residues from crops at harvest. We would
like to use this issue to give a condensed report of some work done here in Florida
by Dr. B. D. Thompson and Dr. C. H. Van Middelem. This work was reported inthe
proceedings of the American Society for Horticultural Science. Vol. 65, 1955;
"The removal of toxaphene and parathion residues from tomatoes, green beans,
celery and mustard with detergent washings."
The object of this work was to determine the feasibility of using certain
detergents to remove typical insecticides from representative crops. Green beans,
tomatoes, mustard greens and celery were used and were sprayed at weekly intervals
with toxaphene at the rate of 2.5 pounds of technical per 100 gallons of water and
parathion at the rate of 0.5 pounds per 100 gallons of water on all crops except
celery. Each crop was harvested at a definite interval following four or five
sprays and the harvested portion washed with the following:
(A) 0.1 percent alkyl oryl polyether alcohol
(B) 1.0 percent neutral soap.
(C) Unsprayed vegetables washed in water
(D) Sprayed vegetables washed in water
(E) Sprayed vegetables not washed.
Solutions were kept at 70 to 750 F. and fresh solution was used for each group
of samples. The washer consisted of a small tank and the water was recirculated,
vegetables were passed over an endless wire mesh belt through a hood where four
top and eight side full jet nozzles sprayed 15 gallons of water per minute at a
pressure of 20 PSI. The mustard greens were immersed in the solutions in large
laundry sinks and were forced to the bottom every two minutes and were rinsed by
plunging them in three 10-gallon portions of water. Then the pesticide residues
were extracted from the vegetables.
Water Triton X-100 Olate Flakes
Tergitol "NPX" Emulsifier "M"
BENS II TOMATOES
ORV "' 7 'M -9-*!a', a,4#
Fig. 1--The effect of detergent washing on the removal of surface
residues of toxaphene from treated materials.
BEANS-I BEANS-II TCMATOES-I TOMATOES-II MUSTARD
Fig. 2--The effect of detergent washing on the removal of surface
residues of parathion from treated materials.
Even though parathion was not applied to celery in this experiment comparable
residue removal could be expected as was obtained on the other crops.
Data was collected on the quality of the vegetables for a period following
washing. During storage after washing, vegetables washed with synthetic detergents
lost more weight than where washed in soap solutions or water alone. The synthetic
detergents caused some injury to beans, but to none of the other crops.
Parathion residues were relatively light and significant amounts were removed
24 hours following application. Highest residues were found on mustard greens
(25 PPM) but were reduced to 3 PPM by detergent washing. Toxaphene residues
ranged from 5 PPM on tomatoes to more than 200 PPM on mustard greens. Water and
detergents removed significant amounts from all vegetables except tomatoes. The
removal of residues by water in most cases, as shown by the graphs, is good.
Neutral soap does a somewhat better job and could be used without creating a
residue problem itself.
In conclusion we would like to emphasize that this information should never
be used to violate recommendations and the use of these methods for removal of
residues should not be necessary when you apply the proper chemical at the
recommended rate and do not apply nearer to harvest than allowed.
Mason E. Marvel
F. S J nson James Montelaro
Vegetable Crops Associate Vegetable
Specialist Crop Specialist