A chemical ingredient of vinyl, used by the toy industry since the early 1980s, because an earlier compound caused liver damage in laboratory rats, caused essentially the same problems in rats in tests done in the mid-90s, a manufacturer of the chemicals acknowledged. With the environmental organization, Greenpeace planning to release a report calling for banning the chemicals in toys, the manufacturer, the Aristech Chemical Corporation of Pittsburg, said the problem was not relevant to humans.