WASHINGTON -- 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 Friday calling for banning the chemicals in toys, the manufacturer, Aristech Chemical Corp. of Pittsburgh, said the problem was not relevant to humans. Aristech said the new material, a "plasticizer" used to make vinyl soft, causes the same liver damage, but said that in the 15 years since the first substance was eliminated, scientists have learned that the process that causes the liver damage occurs in mice and rats, but not humans.
Greenpeace, in its report, plans to say Aristech, a subsidiary of Mitsubishi Corp., knew that the new material was as bad as the old but kept using it. Greenpeace has been on an international campaign against the use of vinyl in toys for more than a year, and has been instrumental in persuading several European countries to consider banning it.
Both substances in question are forms of a class of chemicals called phthalates, (pronounced THAY-lates), which bond with vinyl molecules and make the product flexible. In 1985 a scientific panel reported to the Consumer Product Safety Commission that a type of phthalates called di (2-ethylhexyl) phthalate, or DEHP, caused cancer in animals and might do so in humans. The commission did not ban DEHP but made an agreement with the toy companies that they would switch to diisononyl phthalate, known as DINP, for products like pacifiers and rattles that children might chew on.
Greenpeace tested a variety of toys, including First Years teethers and Hasbro Teletubbies, and found DINP.
But Aristech, which conducted some studies of the new material that showed problems in rats, said these were not relevant. It said it had informed the government of the studies' results over the years and had made no secret of the findings in the scientific community.
James Santory, a division manager with the company, said that DEHP was replaced in the early 1980s as a precaution, "not because we thought it was a hazard, but because we didn't know the science." And, he said, the company expected that the replacement substance, DINP, would cause tumors in rats, and it did.
But "the mechanism that causes cancer is not relevant to humans," Santory said. He added that DINP and DEHP are peroxisome proliferators, meaning that they stimulate production of an enzyme that damages the liver, but that this does not happen in higher animals, including guinea pigs, monkeys and humans.
Asked if DINP should be replaced, he said, "unless the science was advanced, the decision would seem to be the same, but we believe the science has advanced. We're talking about a 15-year period of time."
The Consumer Product Safety Commission is still considering the issue, but a preliminary report on the subject said "it is not clear whether peroxisome proliferation is required" to cause cancer.
The issue of vinyl in toys is complicated for several reasons, among them that there is no standard way to determine how much material in the vinyl a child can realistically be expected to absorb. The standard technique is to give increasing doses to different groups of rats, identify the largest dosage level that does not appear to cause problems, divide that by 100 and set it as the maximum allowable level.
But at Greenpeace, Joe Di Gangi, a biochemist, said, "This one-hundredth is a made-up number, it's a standard they've invented."
Di Gangi said substances that caused cancer in laboratory animals should not be allowed in items that children could chew. He also said DINP had been shown to cause a variety of health problems in rats beyond liver damage that could also be relevant to children.
Some manufacturers have recently decided to stop using vinyl. Santory said this was not because of safety, but for companies making toys, "you don't want to be on the front page of this particular issue."
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