Their incinerators need a set amount of garbage each day to operate efficiently, he said, and incinerator operators charge municipalities penalties when the minimum quantities are is not used.

The defense fund maintains that because of such findings, incinerator operators should be required to test their ash and, if it violates Federal standards, handle it as hazardous waste.

The group, the Environmental Defense Fund, said incinerator operators were not following the law in regularly testing the toxicity levels of ash from their facilities.

The group today mailed notices to over 100 incinerator operators telling them of the findings.

Two questions being asked by incinerator operators yesterday were how often ash would have to be tested, and how many failures would make ash a hazardous waste.

In addition, more training will be required for incinerator operators.

Pennsylvania does not regulate the deals communities make with private landfill and incinerator operators.

That was to overturn an E.P.A. agency regulation that would have required incinerator operators to recycle wastes to be burned.

As a result, incinerator operators are more often being required to take an "integrated" approach, recycling as well as burning.

The state might persuade incinerator operators to expand recycling capacity, or even go into the production of recycled paper itself.