Study of fish endocrine systems and environmental contaminants

[slester@essential.org]

ABSTRACT FROM SETAC (Society of Environmental Toxicology and Chemistry) 
WORLD MEETING IN VANCOUVER, BC, 11-5-95
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Reconnaissance of 17B Estradiol and 11 Ketotestosterone Levels in Fish of 
United States Streams, Steve Goodbred, National Biological Service, 
Sacramento, California, Robert Gilliom, U.S. Geological Survey, 
Sacramento, California, and Timothy Gross, University of Florida, 
Gainesville, Florida.
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A reconnaissance study was conducted to determine whether endocrine 
systems of fish in United States streams may be affected by environmental 
contaminants.  Levels of 17B-estradiol (E) and 11-Ketotestosterone (T) 
were measured in 639 common carp and 126 largemouth bass from streams at 7 
reference sites and 19 potentially affected sites believed to represent a 
range of contaminant conditions that commonly occur throughout the 
nation.  These sites are distributed among 11 major river basins across 
the country.  Nationally aggregated data from this study indicate that 
E/T ratios for carp (both sexes) and female bass are significantly 
depressed at potentially affected sites compared to reference sites.  
Female carp from 8 potentially affected sites had median E/T ratios 
significantly less than the national reference.  

At 5 of these sites more than 25 percent of the females had ratios less 
than 1:1, a characteristic of males.  Most significantly depressed E/T 
ratios in female carp are explained by low levels of 17B-estradiol 
compared to reference sites.  Male carp E/T ratios are also significantly 
lower than the national reference at 9 potentially impacted sites caused 
mostly by depressed 17B-estradiol levels.  Preliminary results using U.S. 
Geological Survey water quality data indicate a high correlation between 
depressed E/T ratios in female carp and median total pesticide 
concentration in water.  

Our initial conclusions from this reconnaissance are that fish from about 
half the potentially affected streams sampled have E/T ratios that 
indicate probable endocrine disruption and that the degree of disruption 
may be correlated with the degree of pesticide contamination. 
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