Does the Hazardous Waste Toxicity Characteristic Apply to Trivalent or Hexavalent Chromium? [40 CFR 261.24]
One of the steps in determining which of your wastes are hazardous waste is to determine if the waste displays any of EPA's characteristics: ignitable, corrosive, reactive or toxic. To determine if a waste is toxic, you can either use your knowledge of the constituents of the waste, or test the waste using the Toxicity Characteristic Leaching Procedure (TCLP). The list of constituents identified in the toxicity characteristic at 40 CFR 261.24 includes chromium (D007). Hexavalent chromium is the most common form of chromium and is recognized as a human carcinogen via inhalation. Trivalent chromium, by contrast, is not considered a significant health hazard. As a result, many people assume that the toxicity characteristic criteria applies to hexavalent chromium only.
Part of this confusion stems from the exclusion at 40 CFR 261.4(b)(6), where EPA has excluded certain trivalent chromium waste streams from the leather tanning industry. This exclusion applies only to those specific waste streams from that specific industry. Wastes generated from other processes (not in the leather tanning industry) cannot take advantage of this exclusion.
EPA has clarified that they are currently regulating chromium as total chromium (Memorandum, Meyers to Valdez; June 8, 1997 (12940)). As a result, both hexavalent and trivalent chromium forms are regulated in 40 CFR 261.24.
While EPA has previously discussed limiting the toxicity characteristic to hexavalent chromium in a proposed rule (45 FR 72029; October 30, 1980), that rule was never finalized.
To help ensure all your hazardous wastes are managed properly, attend Environmental Resource Center's Hazardous Waste Management - The Complete Course, or a state-specific hazardous waste management course in California or Texas.