In non-smokers,

37.3% of the residents in the EZ showed CEV values above the pre-defined reference value of 10 pmol CEV/g globin, whereas in smokers the reference value of 200 pmol CEV g/globin was exceeded in 40.0%. In the non-smokers, some clear patterns with regard to ACN exposure following the train accident were seen in function of the subgroups. First, the evacuation zone (EZ) seems to have been determined 3Methyladenine well by the Crisis Management Team. Outside the EZ, CEV concentrations above the reference level were only observed in 4.2% of the non-smokers, which is in line with what is to be expected on the basis of the definition of the reference value, i.e. the 95th percentile in a non-exposed population. Second, the timing of evacuation seems to have had an effect on the CEV concentrations, especially on the occurrence

of higher concentrations. In zone 1 (EZ1), i.e. the 250 m perimeter of the EZ that was evacuated at night in the hours immediately following the accident, 50.0% of the non-smokers exceeded the reference level, but the CEV levels did not exceed a remarkably low maximum of 65 pmol/g globin. In Zone 2 (EZ2), i.e. the streets parallel with the sewage system and the streets downwind of the train accident that were evacuated in the days following the accident, 35.0% see more had values above the reference level. However, CEV concentrations with maxima in the order of magnitude of several learn more thousands of pmol/g globin were observed. Whether these higher

values reflect a more intense exposure or rather a more prolonged exposure (leading to accumulation of the biomonitoring parameter) is not known. Third, the CEV concentrations above the reference value were observed in the street along the railway and particularly in the streets corresponding to the sewage system. Also the person who died following the accident, as well as the two persons presenting with life-threatening symptoms, lived in the streets along the sewage system. Consequently, the most important route of exposure to ACN for the residents seems to have been by inhalation of ACN vapours, either directly (immediate vicinity of the accident), or indirectly via the sewage system. Differences in CEV concentrations were observed between the residents of zone 2 who had presented at the emergency services (‘EZ2 Emerg’) and the 10% sample of residents of zone 2 who had been evacuated, but did not present at the emergency services (‘EZ2 Evac’). Both groups are living in the same streets along the sewage system and were thus evacuated during the same period of time. In the group ‘EZ2 Emerg’, maxima of 4951 and 12 615 pmol/g globin were observed, whereas in the group ‘EZ2 Evac’ the maximum was 2129 pmol/g globin.