The government proposed tougher guidelines for evaluating cancer risks to children on grounds the very young may be ten times more vulnerable than adults to certain chemicals.

The guidelines, when made final after a review by EPA's science advisory board, would dramatically alter current agency policy, which assumes cancer risks to a fetus or an infant are no greater than for a similarly exposed adult.

For the time being, the increased scrutiny would be limited to assessing a group of chemicals that damage a person's genes by causing them to mutate so that cancer may form more easily later in life. Among these are some pesticides as well as a number of chemicals released in combustion or used in the making of plastics.

The EPA also unveiled broader guidance that attempts to refine and make more precise how EPA scientists evaluate cancer risks when deciding how to regulate a chemical. The new guidance would recommend that scientists give greater weight to the latest science and try to develop a more complete picture.