Since before Wyatt Earp gambled with Doc Holliday in Tombstone, Arizona, and the rich and famous flocked to Monte Carlo casinos on the Riviera, poker chips have been weighted down with lead, a toxic metal. In the latest showdown under the voter-adopted state anti-toxics law, an Oakland nonprofit with a a long string of notches in its environmental-safety belt two weeks ago forged a clean poker chip agreement with a major manufacturer and 21 casino owners to get the lead out.Handling the chips exposes dealers and players to the lead, argued researchers at the Center for Environmental Health. Pregnant women who work at the casinos or gamble regularly put their offspring at risk of mental retardation, and the expectant mothers don't even know it, the group's representatives told the gaming industry during a year of negotiation.Proposition 65, the Safe Drinking Water and Toxic Enforcement Act of 1986, requires businesses to keep chemical at safe levels or warn the public. In this case, the agreement's effect will go beyond California's borders. The signatories promised to comply nationwide, including in the country's gambling capital of Las Vegas.The health advocacy group already has won agreements from manufacturers to eliminate lead from some children's jewelry, candy, talcum powder and plastic rain ponchos, bibs and lunch boxes. Other nonprofits also have worked to educate people about the risks in popular products.Lead is well-documented as a dangerous metal that can retard physical and mental development, and government restrictions in paint, plumbing, gasoline and children's toys have tightened over the years. Studies link exposure to the fetus to lowered IQs in children. The U.S. Environmental Protection Agency and state agencies list lead as a carcinogen, and other studies show associations between exposure and women's infertility and an increase in the risk of heart attacks, strokes and high blood pressure.Some of California casinos promising to use the virtually lead-free chips are California Commerce Club, Golden West Casino, Hustler Casino, Limelight Card Rooms, Lucky Derby Casino, Phoenix Casino and Lounge, Players Club and Village Club Card Room..The full list of signatories is listed in the agreement.The casinos can keep using the leaded poker chips, but they have to post this sign: "Gaming chips used at this establishment contain lead, a chemical known to cause cancer, birth defects and other reproductive harm. Wash hands after handling the chips.