2.2.9.1.10.4.6.4

mixtures with highly toxic ingredients

acute 1 or chronic 1 ingredients with acute toxicities well below 1 mg/l and/or chronic toxicities

well below 0.1 mg/l (if non-rapidly degradable) and 0.01 mg/l (if rapidly degradable) may

influence the toxicity of the mixture and are given increased weight in applying the summation

method. when a mixture contains ingredients classified as acute or chronic 1, the tiered approach

described in 2.2.9.1.10.4.6.2 and 2.2.9.1.10.4.6.3 shall be applied using a weighted sum by

multiplying the concentrations of acute 1 and chronic 1 ingredients by a factor, instead of merely

adding up the percentages. this means that the concentration of "acute 1" in the left column of

table 2.2.9.1.10.4.6.2.2 and the concentration of "chronic 1" in the left column of table

2.2.9.1.10.4.6.3.3 are multiplied by the appropriate multiplying factor. the multiplying factors to

be applied to these ingredients are defined using the toxicity value, as summarised in

table 2.2.9.1.10.4.6.4 below. therefore, in order to classify a mixture containing acute 1 and/or

chronic 1 ingredients, the classifier needs to be informed of the value of the m factor in order to

apply the summation method. alternatively, the additivity formula (see 2.2.9.1.10.4.5.2) may be

used when toxicity data are available for all highly toxic ingredients in the mixture and there is

convincing evidence that all other ingredients, including those for which specific acute and/or

chronic toxicity data are not available, are of low or no toxicity and do not significantly contribute

to the environmental hazard of the mixture.

table 2.2.9.1.10.4.6.4: multiplying factors for highly toxic ingredients of mixtures

a non-rapidly degradable.

b rapidly degradable.