A reconnaissance of the intersex condition in Micropterus dolomieu of the Upper Ohio River Basin as an indicator of anthropogenic endocrine disruptors

The intersex condition has been used as a marker of endocrine disruption in West Virginia. Fifty-two male smallmouth bass from 6 basins on the upper Ohio River were examined for the presence and severity of intersex. Vitellogenin (VTG) RNA levels were quantified as marker of estrogenic contaminants. A significant increase in intersex (p=0.02), ranging from 83.3% to 100%, corresponds with higher population densities and agricultural land (p=0.003). At reference sites, smallmouth bass had intersex frequencies of 16.7% to 33.3%. Vitellogenin results were significantly lower (p<0.001) at impacted sites, consistent with previously reported results in female fish. VTG levels in males were not significantly different. Increased intersex occurrence in males and lowered VTG expression in females have shown that agricultural chemicals and common residential wastewater constituents are likely targets for exploring the relationship between individual EDCs and intersex. There may be a natural background level of the intersex condition.