While investigating the cause of some fish kills in the upper Potomac River, Vicki Blazer and a team of government scientists found a different problem. The male fish Ñ both largemouth and smallmouth bass Ñ were exhibiting female characteristics, such as carrying egg cells.
Now Blazer's group, which is part of the U.S. Geological Survey, is studying both issues. While the focus of the study is fish, the scientists can't ignore the possible effects downstream in the Potomac River where more than three million residents of the region get their drinking water.
"There is a concern in the human population," said Blazer, a fish pathologist. "Fish actually have the same endocrine systems as humans have."
The highest concentrations of fish with signs of gender problems were in the Shenandoah River, Monocacy Creek and the South Branch of the Potomac, Blazer said. They have also found some near the Blue Plains treatment facility in Washington, D.C.
The culprit is likely something called an endocrine disrupter, Blazer said. "Endocrine disrupter" is an umbrella term, which can refer to any of thousands of different chemical compounds.
"I think what people are finding are there are a lot of compounds that are endocrine disrupters," said R. Christian Jones, a biologist at George Mason University.
The disrupters are similar to actual hormones in the body, such as estrogen, a female hormone. Estrogen is still present in males, but at lower levels. "Both males and females have the same hormones, just in different proportions," Jones said.
When estrogen levels increase, the body starts to respond as if it were female, and produce female sex organs, Jones said.
The disrupters are not actually estrogen, but so similar that they fool the body. "It's mimicking real endocrine compounds Ñ real hormones," Jones said.
So far only males have exhibited the symptoms of being "intersex," Blazer said. Blazer and Jones both speculated that there could be a broad range of causes, from something like birth control pills, which could cause sewage to contain extra estrogen levels to water contaminated by hormone-treated livestock.
Jones agreed with Blazer that there is a concern in humans, but he doubts it would be something as dramatic as is seen in fish.
"In humans, maybe less body hair or a swelling of the breasts. It could be showing up in lower sperm counts, something as subtle as that," Jones said.
Jones is optimistic that there will not be serious problems for humans because of the way local water utilities filter the region's drinking water.
"I think there is cause for concern, but I think that a high percentage of these chemicals would be removed," Jones said.
WHILE MOST of whatever is causing the problem for fish might be removed before it reaches the tap in homes, no one knows what a safe percentage would be. Since scientists have not yet been able to determine the exact cause, it is impossible to know if water treatment plants are targeting and removing the correct chemicals.
Both Fairfax Water and the Washington Suburban Sanitary Commission are using advanced filtering techniques.
Fairfax Water uses an activated carbon filter, combined with ozone, said Jeanne Bailey, a Fairfax Water spokeswoman.
"The reason we're confident is our treatment in this has been successful to remove things in these broad categories," Bailey said.
Fairfax Water uses about 140 million gallons of water per day and serves about 1.5 million people, Bailey said. In addition to the normal federally mandated testing regime, it tests for other chemicals. It also makes contributions to water industry efforts to study this and other water-related issues.
"We want to know as much as everybody else," Bailey said. "This is not an issue we're asleep behind the wheel on."
Jones said that the activated carbon filtering is one of the best methods, because it works to absorb organic compounds, including endocrine compounds. The ozone would be more likely to kill bacteria, Jones said. It may serve to destabilize the endocrine compounds, but he is unsure about its potential impact.
WSSC uses about 120 million gallons per day and serves about 1.6 million people, said Mohammad Habibian, environmental group leader.
It uses a method called coagulation, which induces smaller particles to bond with larger ones. The larger particles are then more easily filtered out. WSSC is also among the first in the nation to begin using ultraviolet radiation to treat the water, Habibian said.
Both utilities argue that the fish problem should not carry over into humans. Fish, officials for both said, are immersed in unfiltered water at all times, so they are more likely to come into contact with whatever chemical is causing the problem. Additionally, whatever the fish eat could be contributing to their exposure.
"Fish may be exposed to a much higher concentration, not just through the water, but through the food chain," Habibian said.
Jones said that people could have similar problems. Eating animals with elevated endocrine compounds might have a larger impact on people than drinking the filtered water.
"There are other sources of exposure," he said. "There are just so many possibilities."
While his company is continuing its work to filter the water, Habibian said that the more effective method would be to stop the problem at the source, by discovering it and reducing the amount that runs off into the river.
"Everybody is doing water," he said. "They are missing the big picture."