The U.S. EPA yesterday decided to limit use of lindane and may do the same for endosulfan; both pesticides have been linked to various health problems in humans or animals. EPA's reassessments were spurred by a consent decree last year with the Natural Resources Defense Council, but the environmental group indicated it believes EPA did not go far enough.

Lindane, an ingredient in prescription products used to treat head lice and scabies, ends up in public sewers when users rinse off shampoos and creams. A single lindane treatment can bring 6 million gallons of water up to the 16 parts per trillion level considered unsafe for drinking water, according to a Los Angeles County sanitation expert. Lindane is a persistent organic pollutant that bioaccumulates in the tissues of fish and other animals. In humans, improper usage can result in seizures, damage the kidney and liver, impair the immune system and, in rare cases, lead to death.

At least 14 countries, including Sweden and New Zealand, have banned all uses of lindane. In January, a new California law went into effect, making it the first state in the nation to ban lindane. Canada, Mexico and the United States have agreed to review uses of lindane under the North American Free Trade Agreement's Commission on Environmental Cooperation.

Farmers apply about 1.4 million pounds of endosulfan annually on U.S. crops including cotton, potatoes, apples, tomatoes and grapes, NRDC says. Endosulfan, which smells like turpentine, is also used as a wood preservative. Adults exposed to high levels can experience hyperactivity, nausea, dizziness, headache, or convulsions. Animal studies suggest long-term exposure to endosulfan can also damage the kidneys, testes and liver, and may possibly affect the body's ability to fight infection, but it is unknown if these effects occur in humans, according to EPA.

EPA and NRDC signed a consent decree last year requiring the agency to reassess 11 pesticides, as well as certain classes of pesticides. Yesterday's reassessments stem from that agreement's timetable. EPA's assessments will be subject to a 60-day comment period.

EPA's reassessment removed some registrations for lindane's agricultural uses because of concerns about worker safety. It also included new studies considering exposure to infants through breast milk and traditional diets, such as those of Alaskan Eskimos, which include seal and whale meat that tend to be high in bioaccumulative pesticides.

In its reassessment, EPA said it used a three-fold safety factor designed to protect children and other sensitive groups from pesticide exposure. EPA set people's maximum exposure to the chemical at 1 percent of what is considered safe for animals, then added the additional threefold safety factor. The Food Quality Protection Act generally requires a 10-fold safety factor.

For that reason, NRDC says the reassessments fail to meet the legal requirements intended to safeguard children from pesticide exposure. But EPA chemical review manager Mark Howard, who coordinated the lindane reassessment, said, "We can comfortably say the result [of the reassessment] will be protecting children."

Deborah Altschuler, president of the National Pediculosis Association, which advocates non-chemical treatments for head lice, says people will turn to lindane after all other treatments have failed and often in combination with household lice sprays. These conditions, she says, create a layered exposure to toxic chemicals that EPA doesn't account for.

People also tend to disregard instructions for lice treatments, compounding the exposure problems, Altschuler says. "The only thing that's predictable about lindane is that people will have noncompliance," she says. "Normal use is misuse, and that needs to be considered. To think otherwise is foolish."

Representatives of companies that manufacture lindane could not be reached for comment.

Lindane has also overwhelmed municipal treatment facilities, according to Ann Heil, senior engineer for the Los Angeles County sanitation districts. She said treatment facilities remove about one-fifth of the lindane washed into city sewers, and a nationwide ban on lindane would improve water quality.

"California is very aggressive in setting appropriate limits for wastewater, but a lot of places haven't set them yet," Heil said. "They may be putting too much lindane into the water, but they don't realize it because they're not measuring it."