Uncertainty estimation of exposure factors for consumer products based on various sample sizes.

Usage patterns of consumer products (CP) must be determined for accurate exposure assessments. The purpose was to quantitatively estimate the uncertainty in exposure factors of CP according to various sample sizes. The uncertainty was calculated based on exposure factors of 3,333 participants representing the Korean population referred to as the 'parent population'. Small subsamples of participants randomly selected from the parent population were used to evaluate the exposure factors of 13 CPs. Exposure factors were compared with the corresponding values from the parent population. For all exposure factors, the ratio of the mean values of the 75th percentile of the subsamples to the values of the parent population became closer to 1 as the subsample size increased. For frequency of use factor, the ratio was between 0.9 and 1.1 with sample size of 100 except household bleach and trigger-type bathroom cleaner. For amount of use factor, the ratio was between 0.9 and 1.1 with sample size of 100 except body wash, household bleach, and glass cleaner. These results showed the quantitative uncertainty of exposure factor estimations according to various sample sizes. A sample size of at least 100 subjects should be collected for estimation of exposure factors for most CP.