Workshop report: strategies for setting occupational exposure limits for engineered nanomaterials.

Occupational exposure limits (OELs) are important tools for managing worker exposures to chemicals; however, hazard data for many engineered nanomaterials (ENMs) are insufficient for deriving OELs by traditional methods. Technical challenges and questions about how best to measure worker exposures to ENMs also pose barriers to implementing OELs. New varieties of ENMs are being developed and introduced into commerce at a rapid pace, further compounding the issue of OEL development for ENMs. A Workshop on Strategies for Setting Occupational Exposure Limits for Engineered Nanomaterials, held in September 2012, provided an opportunity for occupational health experts from various stakeholder groups to discuss possible alternative approaches for setting OELs for ENMs and issues related to their implementation. This report summarizes the workshop proceedings and findings, identifies areas for additional research, and suggests potential avenues for further progress on this important topic.

Toxicological evaluation of ammonium 4,8-dioxa-3H-perfluorononanoate, a new emulsifier to replace ammonium perfluorooctanoate in fluoropolymer manufacturing.

Ammonium 4,8-dioxa-3H-perfluorononanoate (ADONA) was developed to replace ammonium perfluorooctanoate (APFO) as an emulsifier in the manufacture of fluoropolymers. The toxicity of ADONA was evaluated in acute and repeat-dose studies of up to 90-days duration, and in eye and skin irritation, dermal sensitization, genotoxicity, and developmental toxicity studies. ADONA was also evaluated as a peroxisome proliferator-activated receptor alpha (PPARα) agonist in rats. ADONA was moderately toxic orally and practically non-toxic dermally in acute studies in rats. It was a mild skin irritant and a moderate to severe eye irritant in rabbits. It was a weak dermal sensitizer in local lymph node assays in mice. ADONA was not genotoxic based on the weight of evidence from five assays. It was not developmentally toxic in rats except at maternally toxic doses. ADONA was a possible PPARα agonist in male rats. The liver was the primary target organ in male rats and the kidney was the primary target organ in female rats. NOAELs in 28- and 90-day oral studies in rats were 10mg/kg/day for males and 100mg/kg/day for females. These findings demonstrate that the toxicity profile for ADONA is acceptable for its intended use and is superior to that of APFO.