If an HPAPI is well-characterized and commercially available already, this information has likely been determined by a toxicologist and is readily available for review and use for classification purposes.
We are seeing a large influx of new chemical entities (NCEs) and experimental/investigational drug compounds that lack a health-based OEL or ADE and have very limited human health hazard/toxicology data. In these specific cases, we look at several sources of scientific information to assist with the proper assignment of an OEB/OHC to the HPAPI of interest:
We prefer human toxicity data on an HPAPI but will accept animal toxicity data when human data is lacking. We review any available data on adverse systemic effects and if determine if they are reversible or not. These distinctions can change the overall risk level of an HPAPI and result in a much higher OEB/OHC band being assigned (default category) where data is lacking or not well understood from a precautionary principle standpoint.
We also verify if the HPAPI is considered genotoxic (cytotoxic), carcinogenic, mutagenic, teratogenic, is a reproductive hazard, or it has any severe dermal or respiratory sensitization potential.
If there is enough scientific information on the HPAPI of interest, we band the compound internally. If not, we will work with an external toxicology firm to assist us in assigning the proper OEB/OHC (e.g., Affygility, Safebridge, etc.).