Human biomonitoring as a tool of objective exposure assessment: A case-study of a major train accident with acrylonitrile in Belgium

摘要

Background: Following a train derailment, several tons of acrylonitrile (ACN) exploded, inflamed and part of the ACN ended up in the sewage system of the village of Wetteren (Belgium). Objectives: The objectives of the present study were: 1) To assess the human exposure to ACN in the populations with the highest suspected exposure, i.e. the local population and the emergency responders; 2) To investigate potential determinants of exposure to ACN; and 3) To explore the association between a biomarker of exposure and self-reported short-term health effects in the local population. Methods: 242 residents and 841 emergency responders participated in the study. N-2-cyanoethylvaline (CEV), a highly specific biomarker for ACN exposure, was measured in blood. To account for potential influence of smoking, cotinine was determined in the urine. Participants also filled in a questionnaire including reporting of short-term health effects. Results: In the evacuated zone, 37.3% of the non-smokers and 40.0% of the smokers had CEV concentrations above the reference values of 10 and 200 pmol/g globin, respectively, at the time of the train accident. Spatial mapping of the CEV concentrations depending on the residential address showed a distribution pattern following the sewage system. The most frequently reported symptoms were local symptoms of irritation. In the non-smokers, a dose-response relation was observed between the CEV concentrations and the reporting of short-term health effects. Overall, the value of self-reported symptoms to assess exposure was limited, with the exception of some local symptoms known to be prominent for the specific chemical exposure studied. Even then, consistent symptom reporting was observed only in case of exposures that resulted in CEV values exceeding 10 times the reference value. For the lower exposure ranges, there was no clear relationship between symptom reporting and exposure. In the emergency responders, 26% of the non-smokers exceeded the CEV reference value. ACN exposure among the non-smokers was predicted by (1) the distance to the accident, (2) the duration of exposure, and (3) the occupational function. In contrast with the local population, CEV concentrations in the emergency responders remained relatively moderate and were comparable with background levels for a smoking population. Conclusion: The present study is one of the first to relate accidental exposure to short-term health effects. The results of this study confirm that a critical view should be taken when considering self-reported health complaints and that ideally biomarkers are monitored to allow an objective assessment of exposure.