The American Environmental Safety Institute (first we’ve heard of it) sued Nestle, Hershey, Mars, and other chocolate manufacturers yesterday for not disclosing that their products contain toxic metals such as lead and cadmium, as required under California law. In a lawsuit filed in Los Angeles County Superior Court, the group said that the levels of the metals in the chocolates like M&Ms posed a health threat, especially to children. California’s Proposition 65 requires that companies warn individuals before they are exposed to dangerous chemicals. But a lawyer for the Chocolate Manufacturers Association said the lawsuit was frivolous and alarmist. She said the two metals are naturally present in chocolate — as they are in other foods — at levels too low to pose any danger.