Results indicated that emergency responders were clearly exposed to ACN from the accident
as 26% of the non-smokers had CEV concentrations above the reference value of 10 pmol/g globin. However, the extent check details of the overexposure in the emergency responders remained moderate. First, while a substantial proportion of the emergency responders exceeded CEV values above what is observed in a background population, the median values observed in both smokers and non-smokers in our population are comparable to what is described in the literature for a non-exposed population (Kraus et al., 2012). Second, even the higher CEV concentrations in the non-smokers (95th percentile of 73 pmol/g globin and maximum of 452 pmol/g globin) remained within the ranges as described for smokers in the literature. Third, the higher CEV concentrations in smokers (95th percentile of 342 pmol/g globin and maximum of 811 pmol/g globin) exceeded only slightly what www.selleckchem.com/products/Bafilomycin-A1.html has been reported in a non-exposed population in Germany (95th percentile of 332 pmol/g globin and maximum of 607 pmol/g globin) (Kraus et al., 2012). The difference of CEV concentrations between smokers and non-smokers is also similar in the study population to what is reported in non-exposed populations, smokers having CEV concentrations largely above the concentrations observed in non-smokers. The CEV contribution due to tobacco
smoking is therefore preponderant in the CEV concentrations of smokers. CART methodology was used to assess
factors predictive of the CEV concentration in the non-smokers. CART offers the advantage of using variables multiple times in different branches of the classification and regression trees, allowing to uncover complex interdependencies between variables. CART can easily incorporate a large number of both numerical and categorical predictor variables, although care should be given to potential overly complex trees as a result of overfitting. Three discriminating factors were identified, i.e., (1) the distance to the accident, (2) the duration of exposure, and (3) the occupational function. The increased CEV concentrations in function of proximity to the accident and exposure duration are in accordance with a direct exposure from the accident and the cumulative character of the CEV biomarker that crotamiton was used, respectively. The interpretation of ‘function’ as predictive determinant is more complicated. First, the ‘function’ turned out to be the most important determinant in the emergency responders without presence in the <50 m zone, with the fire-fighters, the civil protection workers and the group ‘others’ having higher CEV levels than the police and the army. Second, among this group of fire-fighters, civil protection workers and ‘others’, higher CEV concentrations were observed in those who had been present on the field within the 50–250 m zone or further away.