Male fish that are growing eggs have been found in the Potomac River in Maryland, a federal scientist said last week -- indicating that a troubling pollution mystery in West Virginia has spread downstream toward Washington.
Nine male smallmouth bass, taken from the Potomac about 60 miles from the District, were found to have developed eggs inside their sex organs, said Vicki S. Blazer, a scientist overseeing this research for the U.S. Geological Survey.
News of the abnormal fish comes as authorities in West Virginia -- where the fish problem was first noticed in a Potomac tributary -- are investigating whether there is a link to higher rates of certain cancers in people there.
In both places, authorities say the Potomac's problems are likely related to a class of common but little-understood pollutants.
These are spewed out by sewage plants, feedlots and factories, and they apparently are able to interfere with the natural hormone systems that guide all animals' development.
"It's certainly something to be concerned about," said Jim Cummins, director of living resources for the Interstate Commission on the Potomac River Basin. "You don't want to see this kind of change in the biology."
The abnormal Maryland fish were caught near Sharpsburg in Washington County. Blazer, who works at a federal fish lab in West Virginia, said she examined their tissues on slides last week.
"They all have intersex," Blazer said, using the scientific term for a condition in which animals have both male and female elements.
The same symptoms had previously been found about 170 miles farther upstream, in the South Branch of the Potomac in Hardy County, W.Va. Blazer and other scientists discovered the problem there last year as they sought a reason for a rash of mass fish deaths.
Officials are still awaiting the results of water-quality testing that might point to a specific chemical behind the fish problems, Blazer said.
"It certainly indicates something's going on," Blazer said of the new findings in Maryland. "But what, we don't know."
U.S. Fish and Wildlife Service researchers are seeking money for a much larger study across the Potomac watershed.
Similar problems have been found in other types of fish across the country, and scientists believe many of them are caused by pollutants called endocrine disruptors, which short-circuit animals' natural systems of hormone chemical messages.
There turns out to be a vast universe of pollutants capable of driving a hormone system haywire. Some are hormones themselves -- human estrogen from women taking birth-control pills, which can pass through sewage plants untouched, or animal hormones washed downstream with manure. In Hardy County, officials were especially concerned about chicken waste from poultry farms.