Little Pro on 2019-02-09
Acute toxicity classification of a mixture is complicated. It happens very often that you do not have test data on the mixture as a whole or cannot apply GHS bridging principles to the un-tested mixture. In these cases, you have to classify the mixture based on the ingredients with known acute toxicity. In this article, we will explain the traditional Acute Toxicity Estimate (ATE) Method for classifying a mixture for its acute toxicity and give you two examples.
For a mixture containing a substance or more substances that have been classified as acutely toxic, you usually need to calculate the ATEs of the mixture first and then compare it against the classification criteria below to determine the acute toxicity category of a mixture. There are 2 equations to choose depending on whether the total concentration of ingredients with unknown toxicity is less than 10% or not.
To calculate the ATE of a mixture, you must get the ATE of all ingredients with known toxicity and the concentration of each ingredient first. The ATE of an ingredient is:
Now let's see two real acute toxicity mixture classification examples.
Let's assume that we have a mixture containing the following ingredients. The total concentration of ingredients with unknown acute toxicity is less than 10%. Two ingredients have been classified as acutely toxic according to GHS and oral LD50 values are known. The rest 50% of ingredients do not have any acute toxicity.
In this case, we can directly use actual LD50 values as the ATE of ingredients and calculate the ATE of the mixture of containing them as below.
Since the calculated ATE of the mixture is between 50 mg/kg and 300 mg/kg, the mixture itself will be classified as acute oral toxicity category 3 (H301).
Let's assume that we have a mixture containing the following ingredients. The total concentration of ingredients with unknown acute toxicity is less than 10%. Two ingredients have been classified as acutely toxic according to GHS. However, actual oral LD50 values are unknown.
In this case, we can only use converted value as the ATE of ingredients and calculate the ATE of the mixture of containing them as below. The corresponding ATE values of acute toxicity category 4 and category 2 are 500 mg/kg and 5 mg/kg respestively.
Since the calculated ATE of the mixture is between 5 mg/kg and 50 mg/kg, the mixture itself will be classified as acute oral toxicity category 2 (H300).
When a mixture contains more than 10% of ingredients with unknown toxicity, you need to use a different equation. It should also be noted that:
Read more: When to Label Ingredients of Unknown Acute Toxicity under GHS and How
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Tags: Topics - GHS, GHS Classification