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Conservation IssuesIF YOU LOVE THEM
Hannah Suthers

A recent Gary Larson Far Side cartoon depicted a backyard with belly-up robins, a lawn-care truck in the background, and a woman looking out the window and declaring rapturously to her husband, "It must be spring again". We are all familiar with the devastating effects on wildlife of the DDTs (dichlorodiphenyltrichloethanes), chlordanes and other organochlorines, PCBs (polychlorinated biphenyls), the contaminant dioxin found in PCB and in 2,4,5-T (an ingredient in Agent Orange) and the eventual ban of some by the Department of Environmental Protection (DEP) in the 1970's. DDT is still widely used in Africa and tropical Asia, and in Latin America where our migratory birds winter!

These chemicals continue to have an effect on the environment. For example, it was reported at the annual New Jersey Wildlife Rehabilitators' Association workshop in March that Japanese beetles, June beetles and their grubs have become so resistant to chlordane (used around building foundations against termites until banned some 20 years ago) that the poison has biomagnified in their tissue and birds are dying from eating them.

A new problem has been identified, arising from the chlorinated hydrocarbon pesticides and PCBs. The problem is that the poisons disrupt the endocrine system in vertebrates. An endocrine disrupter is an outside agent that interferes with the production, release, transport, metabolism, binding, action, or elimination of natural hormones in the body. These hormones are responsible for the regulation of prenatal and postnatal development processes and for the maintenance of stable equilibrium in the body. During development miniscule amounts, far below the "accepted levels" can do the damage, even as little as ten parts in a trillion.

Since the introduction of DDT, dicofol, kelthane, methoxychlor, dieldrin, chlordanes, dioxins, the alkylphenols in polystryrene and polyvinyl chloride plastics, and some PCBs, strange things have been appearing in the environment. Going up the food chain there are feminization of males and masculinization of females in fishes, birth deformities in fish-eating birds in the Great Lakes, female-female pairing in western and herring gulls, embryonic and chick failure in bald eagles, low clutch viability in American alligators, reproductive failure in common seals and polar bears, to name a few. Emergent human problems have been reported such as increased frequency of undescended testis, 50% decrease in sperm count worldwide during the past 50 years, a rise in hormone-related cancers, prostate disease, endometriosis, a 400% increase in ectopic pregnancies in the United States between 1970 and 1987. These findings have been confirmed in experiments with laboratory animals, and a common denominator of these wildlife and human problems has been identified as a disruption of the endocrine system in various ways. The history of the disastrous use of the synthetic estrogen DES (diethylstilbestrol) in humans is a classic example of previously unknown transgenerational effects of an endocrine disrupter.

Scientists at a 1991 conference at Wingspread, Racine, Wisconsin, were in concordance about the identification of the problems. "We are certain of the following" they reported: "A large number of man-made chemicals that have been released into the environment have the potential to disrupt the endocrine system of animals, including humans." Their report is a book, Chemically Induced Alterations in Sexual and Functional Development: The Wildlife/Human Connection, edited by T. Colborn and C. Clement, Princeton Scientific Publishing, 1992.

These findings and other problems are reviewed by T. Colborn, F. S. vom Saal, and A. M. Soto, "Development Effects of Endocrine-Disrupting Chemicals in Wildlife and Humans", in Environmental Health Perspectives 101 (5): 378-384, 1993. The review article lists some pesticides, fungicides, insecticides, nematocides, and industrial chemicals that are persistent, with widespread distribution in the environment, that are demonstrated to have reproductive and endocrine-disrupting effects. These substances are estrogen mimics and blockers and androgen blockers in the living system, having deleterious effects during critical times of fetal sexual development, maturation, reproduction, and aging. A popular version of the problem is the book Our Stolen Future: Are We Threatening Our Fertility, Intelligence, and Survival? - A Scientific Detective Story, by T. Colborn, D. Dumanoski and J. P. Meyers, Dutton Book, 1996. (Meyers is our own Pete Meyers of the shorebird and horeshoe crab saga, and former Senior Vice President for Science at the National Audubon Society.)

The newer pesticides that act as cholinesterase inhibitors are also a problem to non-target animals and humans, affecting the brain and nervous system For example, in birds the organophosphates lock involuntary body functions "on" until the quivering bird dies of heart or respiratory failure. Carbaryl and other carbamates create a creeping paralysis starting with the extremities so that the birds can't stand or fly. These pesticides are biomagnified up the food chain.

A recent newspaper enclosure of ads from a hardware store included Diazinon insect control for lawn insects offered by the 10-lb. Bag. Diazinon, a cholinesterase inhibitor, is so toxic to birds that a mere five granules with 14.3% diazinon are fatal to a small bird (Balcomb et. Al. 1984, Bull. Environ. Contam. Toxicol. 33: 302-307). In 1990 its use was banned by the EPA on golf courses and turf farms to prevent mass killing of lawn-foraging song birds, ducks and geese. It is ranked as one of the most hazardous compounds to human health. But it is sold for home use! By the 10-lb. Bag! And in containers of liquid concentrate that attach to a garden hose for applying 96 gallons to a lawn!

When will we carry the lesson over into the use of the new pesticides, herbicides, and fungicides? The DEP states clearly that the registration of chemicals by the DEP does not mean that they are safe (US GAO 1986); it means only that they are listed as existing and marketed until proven that the adverse effects are unreasonable compared to their benefits. Before registering the various pesticides, herbicides, and fungicides with the EPA, the manufacturers will have tested them for acute toxicity, carcinogenicity and immediate mutagenicity. But the disasters mentioned above in wildlife and humans are examples of how long-term effects can be missed by conventional lab testing. The reassessment of some 100,000 existing products by the EPA will take well into the 21st century (US GAO 1986). About 1000 new products appear each year.

Meanwhile the Environmental Defense Fund has provided an information service to close the two-year gap between EPA registration and release of information to the public. They list 800 chemicals scored by the EPA and other agencies according to environmental persistence, bioaccumulation potential and human and ecological toxicity. The URL is http://www.scorecard.org. Click on "About the Chemicals", then on "Chemical Profile Search", fill in the chemical name, and look at the "Hazard Rankings".

For endocrine disrupters see: http://www.epa.gov/endocrine/links.html.

We are only now, nearly 60 years later, realizing the long-term adverse effects of the wonders pesticides, herbicides, and fungicides of the 1940s - 1970s. If we have learned anything, when we reach for that bottle or bag of old or new chemical solution to household and backyard problems, we will read labels, look things up, and be wary of what we are doing to our beloved birds - and families.

Some more resources:

Rachel Carson Council, Inc. "What Homeowners Need to Know About Pesticides for the Lawn and Garden". "Alternative Pest Controls for Lawns and Gardens". 8940 Jones Mill Road, Chevy Chase, MD 20815. Phone (301) 652-1877.

Raloff, J. 1994. The Gender Benders. Science News 145: 8 January.

U.S. General Accounting Office, 1986. Nonagricultural Pesticides: Risks and Regulation, Document GAO/RCED-86-97. GAO Document Distribution Center, P.O. Box 6015, Gaithersburg, MD 20877. Phone (202) 275-6241

U.S. General Accounting Office, 1990. Lawn Care Pesticide Risks and Prohibited Safety Claims. Document GAO/RCED-90-134.

U.S. General Accounting Office, 1991. Reproductive and Developmental Toxicants, Regulatory Actions Provide Uncertain Protection. Document GAO/PEMD-92-3.

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Last revision: Monday, June 07, 1999 - 20:39