Used oil and fuel filters are not deemed hazardous. At one time it was though that oil filters contained led from engine bearing wear thus they needed to be treated as hazardous waste and disposed of accordingly. Our company (Fleetguard) and Donaldson Filter undertook a study for the US EPA. We determined that used oil filters did not contain hazardous levels of lead from filtration. What we did determine is that the lead levels in the metal forming process did have levels exceeding EPA requirements. Metal suppliers coated the metals with a lead alloy coating (terne plating). The coating allowed the metals to take form in forging presses while making filter shells (parts for the refrigerator too!). Metal terne plating was discontinued for filter metal supplies back in the late 90s. It is acceptable to dispose of filters in landfills unless local or state law overrules. Scrap metal dealers will take them.....they become rebar in China along with your old Ford tractor.