User Guide to Thresholds and Classification - Environmental ...

156User Guide for Thresholds and Classifications300 < Category 4 2,000 5002,000 < Category 5 5,000 2,5000 < Category 1 50 550 < Category 2 200 50Dermal (mg/kg bw)200 < Category 3 1000 3001,000 < Category 4 2,000 1,1002,000 < Category 5 5,000 2,5000 < Category 1 100 10100 < Category 2 500 100Gases (ppm in air)500 < Category 3 2,500 7002,500 < Category 4 20,000 4,500Category 5 c0 < Category 1 0.5 0.050.5 < Category 2 2.0 0.5Vapours (mg/L in air)2.0 < Category 3 10.0 3.010.0 < Category 4 20.0 11.0Category 5 c0 < Category 1 0.05 0.0050.05 < Category 2 0.5 0.05Dust/mist (mg/L in air)0.5 < Category 3 1.0 0.51.0 < Category 4 5.0 1.5Category 5 cNotes: Gas concentrations are expressed in parts per million by volume (ppmV); mg/kg bw = milligrams perkilogram bodyweight; mg/L = milligrams per litre.a. Category 5 is for mixtures that are of relatively low acute toxicity, but that under certain circumstances maypose a hazard to vulnerable populations. These mixtures are expected to have an oral or dermal LD50 valuein the range of 2,000–5,000 mg/kg bw or equivalent dose for other routes of exposure. In light of animalwelfare considerations, testing in animals in category 5 ranges is discouraged and should be considered onlywhen there is a strong likelihood that results of such testing would have direct relevance for protecting humanhealth.b. These values are designed to be used in the calculation of the acute toxicity estimate for classification of amixture based on its components and do not represent test results. The values are conservatively set at thelower end of the range of categories 1 and 2, and at a point approximately one-tenth from the lower end of therange for categories 3–5.January 2012 EPA0109