Skin notation in the context of workplace exposure standards.

In the establishment of workplace exposure standards, the potential for cutaneous absorption is taken into consideration through the addition of "skin notation" to the relevant substance. In the TLVs Documentation (ACGIH, 1986) dermal lethal dose to 50% (LD50) or human data are the bases for the assignment of "skin notation" to 91 of 168 substances. For the other substances, the "skin" attribution seems to be based on undocumented statements in 24 (14.5%), skin effects in 13 (8%), and analogy in 7 (4%), while in the remaining 33 (20%) any reference is lacking as to the basis for notation of the cutaneous route of entry. Furthermore, since the established "cut-off" value of 2 g/kg is sometimes bypassed when a notation is added or omitted, the use of dermal LD50 is perplexing. Given the relevance of the skin notation for the validation of threshold limit values (TLVs) in the workplace, a full examination and citation of all available scientific data are recommended when establishing the TLV of substances absorbable through the skin.