Household Pollutants Disrupting Fish Genes

National Geographic News
July 29, 2002

Scientists have long known that some "endocrine-disrupting" chemicals in the environment disturb normal sexual reproduction and development in animals. A new study shows the impact appears to be greater in fish, which are susceptible to damage from many more common household pollutants than previously thought.

Researchers from the University of Maryland Biotechnology Institute and its Center of Marine Biotechnology said the increased vulnerability is related to unique physiological mechanisms in the hormone production system of fish.

As a result, harmful compounds in human pollutants interact directly with sex genes in the brain of fish rather than with estrogen receptors in other tissues, the researchers explained.

The results were reported today at the annual meeting of the Society for the Study of Reproduction in Baltimore.

The findings, the scientists warned, have serious implications for the sexual reproduction and development of fish populations in the Chesapeake Bay (and presumably other bodies of water), where surging development in the region is leading to increased discharge of polluting compounds from millions of homes, gardens, and garages.

With thousands of miles of shoreline and an average depth of less than 30 feet, the Chesapeake Bay is considered a prime habitat for fish spawning and hatching.

"I would not say that [the problem] is severe enough that any population is becoming completely mono-sexed," said John Trant, an associate professor at the Center for Marine Biotechnology in Baltimore. "However, because the Bay is so important as a nursery, chemical-induced perturbations of the reproductive and developmental processes could lead to severe consequences."

Chemical "Disrupters"

The research findings were based on two and a half years of lab experiments at the Center of Marine Biotechnology. The scientists found that compounds in a wide range of detergents, plastics, pesticides, medicines, and even thalates (responsible for "new car smell") disrupted the sexual development of juvenile zebra fish.

All of the environmental pollutants were tested at concentrations that can be found in the Chesapeake Bay system.

The scientists discovered that many more classes of environmental chemicals than suspected are functioning as endocrine-disrupting chemicals, and these chemicals are interacting directly with genes that are critical for reproductive success.

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