title: Derivation of an occupational exposure limit for inorganic borates using a weight of evidence approach.
abstract: Inorganic borates are encountered in many settings worldwide, spurring international efforts to develop exposure guidance (US EPA, 2004; WHO, 2009; ATSDR, 2010) and occupational exposure limits (OEL) (ACGIH, 2005; MAK, 2011). We derived an updated OEL to reflect new data and current international risk assessment frameworks. We assessed toxicity and epidemiology data on inorganic borates to identify relevant adverse effects. International risk assessment frameworks (IPCS, 2005, 2007) were used to evaluate endpoint candidates: reproductive toxicity, developmental toxicity, and sensory irritation. For each endpoint, a preliminary OEL was derived and adjusted based on consideration of toxicokinetics, toxicodynamics, and other uncertainties. Selection of the endpoint point of departures (PODs) is supported by dose-response modeling. Developmental toxicity was the most sensitive systemic effect. An OEL of 1.6mgB/m(3) was estimated for this effect based on a POD of 63mgB/m(3) with an uncertainty factor (UF) of 40. Sensory irritation was considered to be the most sensitive effect for the portal of entry. An OEL of 1.4mgB/m(3) was estimated for this effect based on the identified POD and an UF of 1. An OEL of 1.4mgB/m(3) as an 8-h time-weighted average (TWA) is recommended.
authors: University of Cincinnati, 3223 Eden Avenue, Cincinnati, OH 45267-0056, United States. Electronic address: maierma@ucmail.uc.edu.
authors: A
authors: A
authors: Maier
authors: Toxicology Excellence for Risk Assessment, 2300 Montana Avenue, Suite 409, Cincinnati, OH 45211, United States.
authors: M
authors: M
authors: Vincent
authors: The Henry Jackson Foundation, 6720 Rockledge Drive, Suite 100, Bethesda, MD 20817, United States.
authors: E
authors: E
authors: Hack
authors: Toxicology Excellence for Risk Assessment, 2300 Montana Avenue, Suite 409, Cincinnati, OH 45211, United States.
authors: P
authors: P
authors: Nance
authors: Rio Tinto Minerals, 8051 Maplewood Avenue, Building 4, Greenwood Village, CO 80111, United States.
authors: W
authors: W
authors: Ball
mesh_terms: D000395:Air Pollutants, Occupational / Q000592:standards* / Q000633:toxicity; D000818:Animals; D001881:Borates / Q000592:standards* / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007509:Irritants / Q000592:standards* / Q000633:toxicity; D008168:Lung / Q000187:drug effects; D016273:Occupational Exposure / Q000592:standards*; D012098:Reproduction / Q000187:drug effects; D018570:Risk Assessment; D020711:Threshold Limit Values
chemical_list: D000395:Air Pollutants, Occupational; D001881:Borates; D007509:Irritants
keywords: Borate; OEL; Occupational exposure limit; Risk assessment