Title: Toxics and Ecosystem Health: Extended Abstract
Full Citation
Permanent Link: http://ufdc.ufl.edu/WL00001325/00001
 Material Information
Title: Toxics and Ecosystem Health: Extended Abstract
Physical Description: Book
Language: English
Spatial Coverage: North America -- United States of America -- Florida
Abstract: Toxics and Ecosystem Health: Extended Abstract, by Michael Gilbertson
General Note: Box 8, Folder 3 ( Vail Conference, 1993 - 1993 ), Item 39
Funding: Digitized by the Legal Technology Institute in the Levin College of Law at the University of Florida.
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Bibliographic ID: WL00001325
Volume ID: VID00001
Source Institution: Levin College of Law, University of Florida
Holding Location: Levin College of Law, University of Florida
Rights Management: All rights reserved by the source institution and holding location.

Full Text



Michael Gilbertson
International Joint Commission
Windsor, Ontario, Canada

The Great Lakes have proved to be a useful laboratory for toxicologists interested in the
effects of persistent toxic substances in big systems. The case relating effects on reproduction
of wildlife has been best elaborated, and particularly for fish-eating birds such as gulls, terns,
cormorants and eagles. An excellent case has also been made linking consumption of PCB-
contaminated Great Lakes fish to reproductive failure in ranch mink. Research on reproductive
effects on fish such as lake trout and other salmonids has been disappointing and reflects a
reluctance of fisheries biologists to undertake aquatic toxicology, except through controlled
laboratory experiments and fisheries managers to acknowledge that there are contaminants in
Great Lakes fish. Similarly, research on the effects on humans exposed to Great Lakes
Contaminants is more than a decade behind the wildlife paradigm reflecting the reluctance of the
human health authorities to enter this politically controversial field of science.

There has been a wide variety of effects documented. Perhaps the best known is the
eggshell thinning phenomenon in various bird species caused by DDT and its metabolites.
Another syndrome in birds, which was recognized in the 1970s in Lake Ontario colonies
resembled chick-edema disease which had been previously described in poultry. This finding
eventually led to the finding of 2,3,7,8-tetrachloro-dibenzo-p-dioxin in fish-eating birds
throughout the Great Lakes. Further work implicated some of the specific isomers of PCBs in
other outbreaks of chick-edema disease in Green Bay. Meanwhile, epidemiological work was
being undertaken on a cohort of infants whose mothers had eaten Lake Michigan fish
contaminated with PCBs and other organochlorine contaminants prior to pregnancy. These
infants were carried in utero for about a week shorter than a reference group and were smaller
and less well developed. Later testing showed these infants to have cognitive deficits, short term
Memory loss as well as irreversible growth retardation.


In developing wildlife embryos exposed to Great Lakes contaminants in fish, scientists
have observed changes in the process of sexual differentiation. Male embryos of gulls retained
female anatomical parts that should have regressed. This process of feminization of male
embryos has opened up a new field of enquiry into the irreversible disruption of the endocrine
systems that control embryonic development in all organisms including mammals. In addition
to the anatomical changes, there are alterations in neurological and immunological development
and functioning which poses the question of the overall damage to human embryos exposed to
these endocrine disruptors. Some of the compounds are carcinogenic and the question is still
unanswered whether they could be causing cancer in adults exposed in utero via transplacental
movement of the compounds.

One of the most significant advances in this research has been in efforts to make more
rigorous causal statements. In the past five years, Great Lakes toxicologists have borrowed a set
of rules from physical scientists and epidemiologists on how to make causal statements. This
set of agreed rules has been applied to a series of case studies of these chemically induced
diseases in fish, wildlife and humans to deduce or infer whether causal relationships can be
demonstrated. This application of the epidemiological criteria has changed the confidence with
which scientists are prepared to make causal statements. It has also divided the scientists into
two antithetical camps since the traditionalists believe that only statements about "potential
effects" can be made based on a comparison of analytical data with water quality objectives
derived from controlled laboratory experiments. One challenge will be to reconcile these two
approaches into a new paradigm. A second challenge will be to change the environmental laws
and regulations which are based on the old paradigm. In this sense Great Lakes scientists have
not only brought about a socially difficult scientific revolution but also precipitated a societal
challenge to the existing legal framework governing environmental quality. Finally, scientific
developments in the Great Lakes are now being taken through the EPA Great Lakes Water
Quality Initiative to the national level and influencing public policy on a nationwide scale.



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