title: Estimating equations for biomarker based exposure estimation under non-steady-state conditions.
abstract: Unrealistic steady-state assumptions are often used to estimate toxicant exposure rates from biomarkers. A biomarker may instead be modeled as a weighted sum of historical time-varying exposures. Estimating equations are derived for a zero-inflated gamma distribution for daily exposures with a known exposure frequency. Simulation studies suggest that the estimating equations can provide accurate estimates of exposure magnitude at any reasonable sample size, and reasonable estimates of the exposure variance at larger sample sizes.
authors.affiliation: Program in Public Health, University of California, Irvine, CA 92697-3957, USA. sbartell@uci.edu
authors.forename: Scott M
authors.initials: SM
authors.lastname: Bartell
authors.forename: Wesley O
authors.initials: WO
authors.lastname: Johnson
mesh_terms: D015415:Biomarkers / Q000378:metabolism*; D003198:Computer Simulation; D004781:Environmental Exposure; D004784:Environmental Monitoring / Q000379:methods*; D007700:Kinetics; D008628:Mercury / Q000493:pharmacokinetics*; D008954:Models, Biological; D013997:Time Factors
chemical_list: D015415:Biomarkers; D008628:Mercury