Biomarkers in patients admitted to the emergency department after exposure to acrylonitrile in a major railway incident involving bulk chemical material

Background: A railway incident with victims of exposure to the cyanogenic substance acrylonitrile (ACN).

Aims: We retrospectively (i)built an inventory of the clinical characteristics of individuals admitted to surrounding emergency departments (ED's) and (ii)studied the correlation between N-2-cyanoethylvaline (CEV), a biomarker used in a population study for evaluating exposure to ACN, with lactate and thiocyanate (SCN), biomarkers determined during emergency care.

Results: 438 patients from 11 ED's were included and presented with known symptoms of ACN poisoning but also with concern about the risks. A comparison of CEV with lactate or SCN was possible in 108 and 73 patients respectively. CEV was very high in a critically ill patient with a high lactate. There was no correlation with CEV in the patients with normal or slightly elevated lactate concentrations. A correlation of CEV with SCN was only observed in smokers.

Limitations: First there is a lack of data in some clinical files concerning the time and duration of exposure and the smoking-status. A second limitation is that blood samples for biomarkers were not taken systematically in all patients, which may have induced bias. A third limitation is that blood sampling was possibly done outside the correct time window related to the delayed toxicity of ACN. Finally the number of severely-intoxicated patients was low and ACN exposure may not have taken place e.g. in individuals consulting with psychological symptoms. These aspects may have contributed to the below detection limits' analyses of biomarkers.

Conclusions: CEV was markedly elevated in a severely-intoxicated patient with high lactate, a sensitive marker for CN intoxication. We found no correlation of CEV with normal or slightly elevated lactate concentrations but clinicians should consider the possibility of subsequent rises due to the delay in ACN toxicity. CEV correlated with SCN in smokers, which may be explained by ACN in tobacco smoke and deserves further exploration. Further studies are necessary to evaluate the correlation between biomarkers in acute chemical exposures to ACN and these should be carried out prospectively using a preplanned template.