Likewise, the inhalative route will have to be addressed in more detail in order to model exposure levels.
Furthermore, using home and school address histories, we modeled exposure at an individual level, rather than a community level, thereby reducing the potential for exposure misclassification.
As shown in Figure 9, modeling exposure receptors at finer geographic levels of resolution (i.e., census block group rather than ZIP code) reveals localized, neighborhood-level exposure hot spots that are not apparent at coarser geographic scales note in particular the high concentration contours that appear in central Durham under this alternative modeling approach.
Furthermore, the State of California recently proposed reducing the lead MADL to 0.2 μg/day based on modeling of exposure levels that would result in maximum blood lead levels of 15 μg/dL (Cal/EPA 2015a; Cal/EPA 2015b).
Chi-square tests for trend were used for all exposure response models with exposure levels assigned 0, 1, and 2 for nonexposed, ≤ the median, and > the median.
Both models and exposure levels are sensitive to the fat partition coefficient (PF) and the degradation rate for CYP1A2 (CYP1A2_1OUTZ).
For a U-shaped profile, it could be recommended to experimentally verify, or to model, whether the exposure levels are in the same range of doses for which an NMDR relationship is observed.
We compared the deviance of the models at different exposure levels and latencies.
For periods during which a person was not known to have lived in the area, the exposure model assigned background exposure levels (Shin et al. 2011b).
Given the vast number of chemicals in commercial use, improving models to predict exposure levels and pathways is a priority in order to evaluate and manage health risks.
Exposure characterization may rely on historic data such as pesticide application records and wind direction and use mathematical models to estimate exposure levels over time or may involve an intensive field effort to collect samples.
