Environmental Protection Agency auditors are reviewing the agency's handling of an unusual case that put the bite on dozens of dentists because they sold old fillings whose toxic ingredients ended up in the soil. The case has attracted the attention of lawmakers because it tests how far the government can reach to hold parties accountable for toxic waste contamination. Last week, the EPA inspector general's office said it was assigning auditors to conduct a 60-day review of the case before determining whether additional study was necessary. The review comes at the request of a Pittsburgh dental supplier who claims the agency overstepped its authority. The case hinges on amalgam _ the stuff that fillings are made of _ and whether it can be considered a ``hazardous substance'' after it has been removed from peoples' teeth. Amalgam is a hard, durable alloy. Dentists often save old fillings or leftover amalgam and sell it to processors, who break it down into mercury or silver. The EPA alleged in 1987 and 1988 that Pittsburgh dental suppliers Roy Ott, his son Ken, and other companies sold amalgam to metal processor Eugene Bourdeaudhui. As a result of Bourdeaudhui's efforts to break the amalgam down, the agency said soil in Willington, Conn., became so polluted with toxic mercury that it required a $710,000 cleanup in 1985. In seeking out responsible parties to pay for the cleanup, the EPA stunned the nationwide dental community by going after not only Bourdeaudhui but also 58 dentists and several dental suppliers who did business with him. All the parties have settled with EPA, according to attorney Robert Ging of Confluence, Pa. His clients, the Otts, agreed last November to pay the government $30,000 because they said the expense of further legal challenges was too great. In announcing several of the settlements last year, the EPA said the agreements ``demonstrate that members of the dental community understand that they have a responsibility to make themselves aware of dental amalgam's ultimate disposal method and that the dental community _ which controls the disposition of waste amalgam _ rather than taxpayers, should bear the cost of cleanup.'' But Ging said in an interview Tuesday that the principle involved compelled the Otts last month to ask EPA Inspector General John C. Martin to review the case. ``Mr. Ott and his son were so offended by the waste and the injustice of the whole procedure that they felt it ws worth their time and effort to bring this to the attention of the Congress and the people,'' Ging said. Several lawmakers agreed with the Otts that the case raised basic fairness questions. ``The fact that dental amalgam is considered a hazardous waste under Superfund comes as a surprise to many,'' said Rep. Doug Walgren, D-Pa., in a letter last year to EPA. ``A substance which is in my mouth _ and the mouths of millions of Americans _ and is deemed `safe' by dentists and the American Dental Association hardly seems a candidate for Superfund coverage.'' Walgren also said it ignored ``a common sense standard of reasonableness'' to hold Ott and the dentists responsible for the actions of a ``third party'' in Connecticut. Through the Freedom of Information Act, the Otts obtained EPA documents they said demonstrated excessive charges by contractors for the cleanup. ``We share your concern that contractors may be charging excessive fees under the Superfund law,'' Rep. John Dingell, D-Mich. and chairman of the House Energy and Commerce Committee, said in a letter to the family several weeks ago.