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Ecotoxicity Factor (for avlogEC50)

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smy503's picture
Ecotoxicity Factor (for avlogEC50)


I have some questions about the EF for HC50. 

I have discussed with my supervisor about the average logEC50 that using as one of parameters to calculate CF for ecotoxicity impacts. In USEtox, the HC50 is calculated based on the geometric mean of the EC50s of the species measured. As what I understood is, this is less considered about the species sensitivity factors, such as, for the Daphnia (most sensitive species) will give very low EC50 and meanwhile for certain fish (less sensitive species) will give higher EC50, then when we calculate the average, it will be biased. Is it possible if we only use 1 single species average EC50 for the avlogEC50 parameter on the USEtox column? For my case, I am doing LCA on pharmaceutical waste disposal, and I will include the APIs on my study, so I will have to calculate for the APIs emissions using USEtox. As an example, for acrivastine, the estimation value (using QSAR tool) of EC50 for daphnia is 12.54mg/l, and only found 1 related study but, there are another 2 EC50 values for algae and fish, so, can I use only that value as the avlogEC50, without calculate its geometric mean?

If I was wrong, could you explain to me more about this?


USEtox Team
USEtox Team's picture
USEtox ecotoxicity effect factors

Thank you for your question.

In USEtox, we are calculatingn the HC50 across all tested species with available  EC50 data to represent the average pressure on an entire aquatic ecosystem (in contrast to only reflecting the effect on a single species that might or might not be  the most sensitive species - e.g. Daphnia is  not in all cases more sensitive than other species). The geomean across species EC50 represents exactly this average pressure at the ecosystem level and hence you should always use all avaialble EC50 values and not only a single value out of several that are available. The geomean (in contrast to the average) will not be much biased by less sensitive species.

For a full documentation of the HC50, please see Chapter 10 of  the official USEtox 2.0 documentation.