User Guide to Thresholds and Classification - Environmental ...

147User Guide for Thresholds and Classificationssame manufacturer, unless there is reason to believe there is significant variation such that the toxicity ofthe batch has changed. If the latter occurs, new classification is necessary.c. Concentration of highly toxic mixturesIf a substance as a mixture is classified as category 6.1A, and the concentration of the components of themixture that are 6.1A are increased, the new substance as a mixture should be classified as category6.1A without additional testing.d. Interpolation within one toxicity classIf mixtures A and B are in the same toxicity category, and mixture C includes toxicologically activecomponents with concentrations intermediate to those in mixtures A and B, then mixture C is assumed tobe in the same toxicity category as mixtures A and B.e. Substantially similar mixturesGiven:i. two mixtures: (A + B) and (C + B);ii. the concentration of ingredient B is essentially the same in both mixtures;iii. the concentration of ingredient A in mixture (A + B) equals that of ingredient C in mixture (C + B);andiv. data on toxicity for ingredients A and C are available and substantially equivalent; that is, they are inthe same hazard category and are not expected to affect the toxicity of B; thenif mixture (A + B) has already been classified by testing, mixture (C + B) can be assigned the samecategory.f. Aerosolsi. Aspiration hazardA hazard classification relating to aspiration hazards will not generally be applicable for aerosolproducts. The key consideration for aspiration hazards is whether a pool may be formed in the mouththat can then be aspirated. For aerosol products it is unlikely that a pool in the mouth will be formed(unless deliberate misuse occurs), and the exposure necessary for the hazard to present will,therefore, be unlikely to occur.ii.iii.Acute oral toxicityA hazard classification relating to acute oral toxicity will not generally be applicable for aerosolproducts. The exposure necessary for an acute oral toxicity hazard to present is unlikely to occur.Acute dermal toxicityA hazard classification may be assigned for acute dermal toxicity for aerosol products. However, thepropellant should generally not be taken into account when classifying aerosols, as the gaseouspropellant will not be present in the liquid that comes into contact with the skin.January 2012 EPA0109