Household Chemicals Harm Chesapeake Bay Fish
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Household Chemicals Harm Chesapeake Bay Fish
Date:
Sat, 24 Aug 2002 13:13:51-400
From:
Stephen Tvedten <steve@getipm.com>
Organization: Get Set Inc. (www.getipm.com)
To: Paul Helliker <phelliker@cdpr.ca.gov>
Director, State of California, Department of Pesticide
Regulation
cc: Christine Whitman whitman.christine@epa.gov
Household Chemicals Harm Chesapeake Bay Fish
http://ens-news.com/ens/aug2002/2002-08-21-09.asp#anchor2
BALTIMORE, Maryland, August 21, 2002 (ENS) - Traces of ordinary household products may be interfering with sexual development and reproduction of fish in the Chesapeake Bay.
The large, shallow Bay, which has an average depth of less than 30 feet and is fed by hundreds of tributaries, offers valuable habitat for fish spawning and hatching. But, as scientists of the University of Maryland Biotechnology Institute (UMBI) reported at the annual meeting of the Society for the Study of Reproduction this week, runoff water carrying tiny amounts of common home and garden chemicals is now rendering that habitat unsuitable for fish breeding.
"This is worse than we thought before," said Trant. "This is not simply toxicology. It is interfering with the reproduction of the adults, and potentially skewing sex ratios of the populations."
For almost 20 years, scientists have known that some environmental chemicals, known as endocrine disrupting chemicals, disrupt reproduction by mimicking natural estrogens. Now, many additional classes of chemicals, functioning as endocrine disruptors, are interacting directly with genes that are critical for reproductive success, the scientists reported.
Chemical disruption of a brain gene, which directly affects brain estrogen production, may be a key mechanism for the disruption of the developmental and reproductive capacity of fish. Unlike most animals, many fish produce two forms of a gene responsible for aromatase, an enzyme that makes estrogen - one form in the ovaries, the other in the brain.
Compounds in many detergents, plastics, pesticides, some medicines, and even thalates that keep vinyl soft in cars were shown to disrupt the sexual development of juvenile zebra fish in experiments at UMBI's Center of Marine Biotechnology (COMB) in Baltimore. All of the environmental pollutants were tested at concentrations that can be found in the Chesapeake Bay system.
"I would not say that it is severe enough that any population is becoming completely monosexed. However, because the Bay is so important as a nursery, chemical induced perturbations of the reproductive and developmental processes could lead to severe consequences," said John Trant, COMB associate professor.
First, the researchers discovered that the "differential expression of the brain aromatase gene" was associated with sex differentiation.
"It became clear that compounds affecting this gene will thereby affect sex and sexual behavior in fish," concluded Trant. The researchers found that the endocrine regulating gene in the brain can affect more than whether a fish becomes male or female.
"What is dangerous is that in between stuff," Trant explained. "You might get males who do not display the correct behavior. In order to mate with a female, he may have to court her, build a nest, chase, or show some form of dominance. So, even if the concentration of these disrupting compounds in the water are not sufficient to completely reverse their sexual physiology, small adjustments in their behaviors would be equally fruitless."
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