MANY Americans assume that the chemicals in their shampoos, detergents and other consumer products have been thoroughly tested and proved to be safe.

This assumption is wrong.

Unlike pharmaceuticals or pesticides, industrial chemicals do not have to be tested before they are put on the market. Under the law regulating chemicals, producers are only rarely required to provide the federal government with the information necessary to assess safety.

Regulators, doctors, environmentalists and the chemical industry agree that the country’s main chemical safety law, the Toxic Substances Control Act, needs fixing. It is the only major environmental statute whose core provisions have not been reauthorized or substantively updated since its adoption in the 1970s. They do not agree, however, on who should have to prove that a chemical is safe.

Currently this burden rests almost entirely on the federal government. Companies have to alert the Environmental Protection Agency before manufacturing or importing new chemicals. But then it is the E.P.A.’s job to review academic or industry data, or use computer modeling, to determine whether a new chemical poses risks. Companies are not required to provide any safety data when they notify the agency about a new chemical, and they rarely do it voluntarily, although the E.P.A. can later request data if it can show there is a potential risk. If the E.P.A. does not take steps to block the new chemical within 90 days or suspend review until a company provides any requested data, the chemical is by default given a green light.