256d - Barriers to developing BEIs® for adipates

Abstract The committee reviewed the feasibility of developing BEIs® for adipates, chemicals that are widely used in the manufacture of a remarkable variety of products as plasticizers, emollients and lubricants. Their usage is likely to increase as they can substitute for phthalates. This assessment focused on eleven adipates that are esters of adipic acid for which occupational exposure values have not been assigned. Adipates are lipophilic with low vapor pressures which suggests that in occupational settings, the primary route of exposure would be through skin. Skin exposure is supported by studies noting the excretion of urinary metabolites after application of di-n-butyl adipate (DnBA) -containing sunscreen. Despite the possibility of worker exposure, no occupational assessments were found. Background exposure is a concern since small surveillance studies of urinary metabolites of two adipates, diethylhexyl adipate (DEHA) and DnBA provide evidence of exposure among the general population lacking known occupational exposure. Research on human toxicity is non-existent while animal models suggest little adverse effect at low doses. Robust analytical methods for the quantitation of specific urinary metabolites have been described for three of the adipates -- DEHA, DnBA, and diisononyl adipate (DINA). Accordingly, it was not possible to establish a meaningful value of BEI® for any of the selected adipates given the lack of evidence of systemic adverse health effects, the likely high background levels in those without occupational exposure, and the lack of studies demonstrating a relationship between the urine measures and existing guidelines, biological changes, or health risk.