Assessing exposures to PCBs after an accidental fire in an electric transformer in France: (ir)relevance of human biomonitoring

摘要

In June 2013, a fire occurred in an electrical transformer in process of dismantling. The local health authorities considered to launch a program of prevention of contamination, environmental measurements, and health monitoring for the following reasons: there were doubts on pyralene remnants in the transformer and the fire could not be extinguished exposing to black smoke residents who refused evacuation. Objective The objective is to review the different steps of the procedure dealing with a power transformer fire: from exposure identification, to potential contamination calculation, selection of candidates for measurements and ways of differentiating acute exposure to the fire from chronic exposure to a contaminated soil. Methods A field investigation was initiated with geographical grid mapping and questionnaires for residents in order to assess the environmental and health impact. A step by step environmental contamination (PCB-L, PCB-NL, dioxins and furans) measuring plan was launched and a biological monitoring study (blood and urine samples, with specific blood sampling and conservation in case of necessity of dioxine measurements) was proposed to the symptomatic residents. Results Only the supposed most exposed quarter could be checked since the population ("Roma community") concerned was difficult to approach. Recommendations to prevention dietary contamination and tracking were scrupulously respected and no traces from the fire were observed upon visual inspection. Most of the interviewed residents declared headaches, and symptoms of irritation. Four residents were admitted to hospital due to a suspected of carbon-monoxide intoxication which revealed to be compatible with smoking habits. Measurements in soil highly exposed to fire-fighting operations and in the near field of the transformer did not reveal elevated concentrations (PCDD-TEQ. = 2,7 ng/kg - PCB-TEQ. 8.0 ng/kg). It turned out there was no demand for any biological monitoring. Conclusion Due to the high expense and technical difficulties to perform dioxine monitoring the local authorities stopped preparations for the monitoring process study.Targeting on PCB- congeners (including "lower chlorinated") for biomonitoring in combination with soil measurements could have highlighted more easily the exposure to the transformer and the acute exposure from the past ones. Nevertheless the acceptability of biomonitoring measurements by the exposed population remains an issue as well as the balance between advantages and disadvantages of such an action on a public health point of view.