The 1976 law is written in such a way that it can be almost impossible for the E.P.A. to do a satisfactory job, in part because it does not require manufacturers to provide safety data before a product hits the market.

These changes represent a big improvement over the 1976 law, the Toxic Substances Control Act, under which the E.P.A. has been able to ban or restrict the production or use of only five chemicals out of the roughly 85,000 in use today.

In 1989, the environmental agency banned most asbestos-containing products, but two years later the United States Court of Appeals for the Fifth Circuit overturned the ban for many products containing asbestos

The biggest potential problem is that it would pre-empt states from imposing restrictions on chemicals that the E.P.A. has reviewed or is in the process of evaluating. State laws and regulations enacted before April 22 would be allowed to stand and states could ask for waivers from pre-emption for laws or regulations enacted after that date.

Click to read New York Times article on Toxic Substances Control Act