Exposure metrics for diesel and gasoline emissions that were modeled included: ever exposure, cumulative exposure, and concentration of exposure.
The mean hourly concentration of exposure was estimated at each participant's home by means of a time-dependent finite dispersion model combined with subgrid models to describe the source contribution to the grid concentrations.
Concentration of exposure could not be estimated in absolute terms; it was only done on an ordinal scale.
Only two cases and one control reported working in a job with an assigned 'high' concentration of exposure.
Additional studies characterized the depression of liver non-protein sulfhydryl content (primarily GSH) with the duration and concentration of exposure to VC.
However, toxicologic studies conducted to date support only the notion that concentration of exposure has a direct impact on the degree of toxicity and/or DNA damage acquired.
Although the patterns of duration and concentration of exposure were similar, there were slightly more very long duration-exposed workers among the non/low smokers.
The optimal time and concentration of exposure was determined for DHT, testosterone, and different combination of the TBECH diastereomers β, 50 50 αβ, 50 50 γδ, and 25:75 γδ.
Where risk by cumulative exposure was not published, it was derived as the product of mean estimated concentration of exposure in each group for which risk was reported and the mean duration of exposure in that group.
These observations suggest that an exposure threshold may exist for the genotoxic effects of diesel exhaust particles, and this is consistent with the results of our analysis, where concentration of exposure, but not duration alone, was associated with cancer risk.
Animal data on mucociliary clearance, which parallels that of human data, was extended to show that concentration of exposure was more important than time of exposure in eliciting a response, although time played a significant role.
