Roy, T.A., W.E. Dalbey, and C.R. Mackerer. ³ C₁₂-Chlorinated Paraffins: Workplace Exposure and Risk Assessment. The Toxicologist 1998. 42(1-S): 225. Abstract #1108.

chlorinated paraffins

The widespread use of (C10-C30) chlorinated paraffins (CPs) in industrial applications and the continued concerns regarding workplace exposure to these materials has prompted a reexamination of in-house CP oral/dermal bioavailability data together with published CP oral toxicity data to make exposure and risk assessments based on contemporary models. In vivo and in vitro oral and dermal bioavailability experiments were conducted in-house with C12-, C18-, and C23-CPs (~40-60% Chlorine). In vitro percutaneous absorption experiments were also conducted with human skin sections. The measured CP dermal flux (J) values were converted to dermally absorbed dose (DAD) values using EPA recommended default values. DAD values ranged from 0.037 to 0.00046 mg/kg/day for C12- and C23-CP, respectively. The low dose linear extrapolation model was used to determine a slope factor (SF or q*) for the C12-CP based on the results of a NTP two-year oral feeding study. Toxicity equivalent factors (TEFs) were estimated for C14-17-Cps and C22-26-Cps based on a comparison of published data from subchronic oral studies Cancer risk (CR=1-exp(-DAD x q*) resulting from dermal exposure were based on EPA procedures. The CR calculations, using the in-house DADs and the C12-CP slope factor, were adjusted for relative oral bioavailability (in-house data) and relative potency (TEFs). The risk associated with workplace dermal exposure to C12-CP was estimated to be approximately 1 in 20,000. The corresponding estimated risk for C23-CP was 1 in 5,700,000 and for C14-C17-CPs, 1 in 200,000.