California to develop selenium standard for wildlife

The California offices of the U.S. EPA, the U.S. Fish and Wildlife Service (USFW), and several other agencies have agreed to develop an aquatic standard for selenium to protect wildlife in California. This would be the first water quality regulation intended to protect birds and other wildlife in addition to fish. The move comes at a time when draft federal EPA guidelines, which used selenium tissue concentrations in fish as the basis for revising water quality recommendations, have been blocked for almost a year by objections from USFW.

Selenium is an essential micronutrient, but at high concentrations it leads to reproductive abnormalities in fish and birds. Its toxic effects have been the topic of furious debate among aquatic toxicologists for more than 10 years. Government scientists charged with protecting wildlife say existing standards must be tightened because selenium contamination is widespread, but industry scientists say that it is an environmental oddity and that EPA’s draft addresses the issue.

Like mercury, selenium’s aquatic cycle is complex and diet is the main exposure route. Consequently, EPA’s current chronic criterion for selenium, 5 parts per billion (ppb) in water, is often not closely related to the amounts found in fish. EPA’s draft selenium chronic criterion, completed in March 2002, used tissue concentrations with the intent of safeguarding fish reproduction. Toxicologists agree that tissue concentrations “offer an opportunity to let the fish tell us whether the environment is safe,” says William Adams, senior science adviser for Rio Tinto, a mining company. “I think the selenium chronic criterion is a unique step forward in environmental protection.”

However, USFW claimed that the draft standard could lead to adverse reproductive effects in many of California’s threatened and endangered species and delayed it by appealing to the Endangered Species Act.

EPA’s draft is overly simplistic because it doesn’t account for food webs, counters U.S. Geological Survey (USGS) scientist Theresa Presser, in Menlo Park, Calif. As an example, Presser cites the San Francisco Bay, where bass that feed on algae have low selenium levels, but sturgeon that feed on bivalves, which concentrate selenium, get a high dose. To know which wildlife is at risk, it’s necessary to understand the ecosystem, she says.

In addition, EPA’s draft guidelines say little about implementation—the details of what, when, and how to analyze fish, or how to set water discharge permits so that fish tissue concentrations stay low. Implementation oversights in EPA’s mercury tissue guidance, which is intended to protect humans who eat fish, have caused chaos in states and agencies, according to USGS scientist Steve Schwarzbach in Sacramento, Calif. But EPA would have produced implementation guidance for selenium if the new standard hadn’t been sidelined, counters EPA selenium project manager Charles Delos, in Washington, D.C. —REBECCA RENNER