User Guide to Thresholds and Classification - Environmental ...

430User Guide for Thresholds and ClassificationsSee Table 22.5 and the worked example below.Table 22.3: Classification of a mixture for terrestrial invertebrate hazards based on summation of classifiedcomponentsProcess Sum of % of components classified as Cut-off Mixture classified asStep 1 9.4A x M ≥ 25% 9.4AStep 2 (9.4A x M x 10 ) + 9.4B ≥ 25% 9.4BStep 3 (9.4A x M x 100 ) + ( 9.4B x 10) + 9.4C ≥ 25% 9.4CNote: M = multiplying factor.Table 22.4: Terrestrial invertebrates: multiplying factorsLD 50 value ( g/terrestrial invertebrate)Multiplying factor (M)0.2 < LD 50 2 10.02 < LD 50 0.2 100.002 < LD 50 0.02 1000.0002 < LD 50 0.002 10000.00002 < LD 50 0.0002 10,000(continue in factor 10 intervals)Note: LD 50 = median lethal dose.Table 22.5: Example calculation for terrestrial invertebrate classification of Mixture ZComponentLD 50( g/terrestrialinvertebrate)Classificationof componentConcentrationof componentin mixture (%)Multiplyingfactor (M)Weightedconcentration ofcomponent inmixture(M x %)B 5 9.4B 5 - 5P 0.01 9.4A 0.05 100 5Q 1 9.4A 1 - 1T 20 9.4C 40 - 40U 100 Not classified 53.95 - 53.95Note: LD50 = median lethal dose.The steps to follow in applying the summation approach to terrestrial invertebrate hazard classification formixtures with highly toxic components are set out below, using the information in Table 22.5.January 2012 EPA0109