Investigators are looking into whether New York suppliers sold heating oil cut with waste oil, posing an environmental health threat, officials said. Authorities raided at least five heating oil companies March 12, The New York Times reported Wednesday. Within days, some owners of commercial and residential buildings filed lawsuits against oil giant Hess Corp. and Castle Oil Corp., which describes itself as one of the largest heating oil distributors in the metropolitan area. The companies have denied any wrongdoing. Castle said its products are tested daily at an in-house laboratory and inspected five days a week by city officials. An attorney filing a lawsuit against Hess said in court Hess may have been an unwitting participant in the illegal manipulation of its products, the Times reported. A state Supreme Court Justice ordered the companies to cease and desist selling heating oil cut with waste oil. Robert F. Kennedy Jr. -- senior attorney for the Natural Resources Defense Council and one of the attorneys who filed the lawsuit against Castle -- said burning waste oil in building heating systems could release a barrage of toxic pollutants. \"Basically that company has turned every boiler or furnace it services into a toxic waste incinerator,\" he said. \"When you burn waste oil, there is a tremendous amount not only benzene, toluene and xylene, which are known carcinogens, but in addition there is an inventory of heavy metals that are extremely toxic, including mercury, lead, arsenic, cadmium, antimony and zinc.,\" Kennedy said. Authorities raided Statewide Oil & Heating in Brooklyn, which has delivered oil for Hess and Castle at different periods; County Oil Company and J. B. Waste Oil Company in Queens, N.Y.; New York Oil Recovery Corp. in Brooklyn; and Paradise Heating Oil, in Ossining, N.Y., the Times said. The Internal Revenue Service and the New York State Department of Environmental Conservation are also investigating, the Times reported.