It is worth noting that while this is great progress, the CPCA categories are still quite conservative (which is acknowledged by EMA) and read-across might provide a more appropriate basis for an AI. For example, EMA has an AI of 78,000 ng/d for nitroso-mefenamic acid based on read-across from nitroso-diphenylamine. If they used a CPCA-derived AI rather than read-across, the limit would be 1500 ng/day (52-fold lower). It’s important to continue to have the flexibility to use read-across when it can be justified, so hopefully a CPCA-derived AI is treated as a refined default (analogous to a tiered TTC approach) and not a firmly established AI.
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