Uncertainty analysis of the estimated ingestion rates used to derive the methylmercury reference dose.
The U.S. EPA's Reference Dose (RfD) for methylmercury (MeHg) uses a simple one-compartment toxicokinetic model to estimate ingestion doses in mg/kg-day from measured concentrations of mercury in hair. The model includes a number of input variables for which point estimates are made. Uncertainty in the inputs is addressed by the use of a 3-fold uncertainty factor. There are, however, published ranges for each variable which are used to develop distributions for each of the inputs. Monte Carlo output of the model is generated. The 90% confidence interval spans a 3-fold to 5-fold range of ingestion doses for any given concentration of mercury in hair. The hair:blood mercury concentration ratio contributes most to the variance of the output. The results indicate that the uncertainty factor of three is appropriate.
Swartout
J
J
National Center for Environmental Assessment, U.S. Environmental Protection Agency, Cincinnati, OH 45268, USA.
Rice
G
G
D004305:Dose-Response Relationship, Drug; D005260:Female; D006197:Hair / Q000737:chemistry; D006801:Humans; D008297:Male; D008452:Maximum Allowable Concentration; D008767:Methylmercury Compounds / Q000493:pharmacokinetics* / Q000633:toxicity; D009010:Monte Carlo Method; D019055:No-Observed-Adverse-Effect Level; D011336:Probability; D015203:Reproducibility of Results; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D014481:United States; D014484:United States Environmental Protection Agency
D008767:Methylmercury Compounds