aquatic toxicity

Can somebody please help explain how to use the GHS additivity formula method in part 3 of the GHS to calculate Aquatic toxicity?

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Hi there,
Please find our response to your question below, if you have any additional questions please do not hesitate to contact us!
Also, Chelsea recieved another question via email regarding aquatic toxicity, which we will also address below:

Question 1) :
Can somebody please help explain how to use the GHS additivity formula method in part 3 of the GHS to calculate Aquatic toxicity?

Response:
The fourth revised edition of the GHS is available for viewing or purchase at the following link:
http://www.unece.org/trans/danger/publi/ghs/ghs_rev04/04files_e.html
In the fourth revised edition of the GHS, Chapter 4.1 addresses hazards to the aquatic environment. The equation to which I believe the commenter is referring is that set forth in Chapter 4.1.3.5.2. The application of this equation is described further in Chapter 4.1.3.5.3.
In brief, the equation set forth in 4.1.3.5.2 weighs the concentration of each ingredient with the aquatic toxicity of that ingredient. In other words, we assume that the dilution of each ingredient reduces the aquatic toxicity of that given ingredient. Chapter 4.1.3.5.3 indicates that ideally we should use aquatic toxicity data from the same taxonomic species, but it also states that if we don’t have data for all ingredients for the same species, we can use what we have. In that case, we are supposed to use the toxicity value from the most sensitive species.
In practical terms, that means the first step is to identify aquatic toxicity data for each ingredient if it is not provided by the supplier of that ingredient. While there are a number of relevant resources for this information, I would recommend the ECHA registered substances database and I would also recommend the USEPA ecotoxicology database, the links for which are pasted below:
http://echa.europa.eu/web/guest/information-on-chemicals/registered-substances
http://cfpub.epa.gov/ecotox/
Once aquatic toxicity information is located for each ingredient or for some of the ingredients, Chapter 4.1.3.5 describes the process for calculating the estimated aquatic toxicity of the mixture. This topic will also be covered in detail in the upcoming recertification webinar.

Question 2):
If we do not have aquatic toxicity data of the whole product for three of the four acceptable taxa, could we demonstrate the lack of toxicity as outlined under the GHS purple book driven by raw material data and weighted-average calculations in the absence of data?

Response:
Yes. Chapter 4.1.3.5 is for the classification of mixtures when toxicity data are available for all ingredients or only for some ingredients. The application of the equations set forth in 4.1.3.5.2 is appropriate.

Thank you!
The EcoLogo Program