S Bridgman1. 1. Industrial and Community Health Research Centre, Department of Postgraduate Medicine, University of Keele, UK. Stephen.Bridgman@lnsha.wmids.nhs.uk
Abstract
BACKGROUND: A factory fire in Tranmere, Merseyside, England, deposited asbestos containing fallout in an urban area. There was considerable community anxiety for months after the incident. Therefore an assessment of the long term health risks of this acute environmental incident were requested by the local health authority. METHODS: The facts of the incident were gathered and appraised from unpublished and press reports, involved personnel, and further analysis of material collected at the time of the incident. The literature on the long term health risks of asbestos was reviewed, and combined with evidence on asbestos exposure to estimate community health risk. RESULTS: Risk was almost entirely from exposure to fire fallout of chrysotile in asbestos bitumen paper covering the factory roof. Amosite was only detected in a few samples and in trace amounts. The number of people who lived in the area of fallout was 16 000 to 48 000. From a non-threshold model with assumptions likely to overestimate risk, the lung cancer risk is estimated to be undetectably small. Risk of mesothelioma from chrysotile exposure, and risks of lung cancer and mesothelioma from amosite exposure were based on observational studies and were estimated to be even lower than that of lung cancer risk from chrysotile exposure. Academically, there are assumptions that while reasonable cannot be proven, for example, the validity of extrapolating observed risk from much higher exposures to lower exposures, estimates of individual exposure, and that there is no threshold for asbestos to cause cancer. CONCLUSIONS: The author is unaware of a similar study on long term health risks in a community exposed to asbestos in a fire. It is concluded that, using methods that do not underestimate risk, risk is undetectably small. Practical lessons from this methodology and approach to health risk assessment are discussed.
BACKGROUND: A factory fire in Tranmere, Merseyside, England, deposited asbestos containing fallout in an urban area. There was considerable community anxiety for months after the incident. Therefore an assessment of the long term health risks of this acute environmental incident were requested by the local health authority. METHODS: The facts of the incident were gathered and appraised from unpublished and press reports, involved personnel, and further analysis of material collected at the time of the incident. The literature on the long term health risks of asbestos was reviewed, and combined with evidence on asbestos exposure to estimate community health risk. RESULTS: Risk was almost entirely from exposure to fire fallout of chrysotile in asbestos bitumen paper covering the factory roof. Amosite was only detected in a few samples and in trace amounts. The number of people who lived in the area of fallout was 16 000 to 48 000. From a non-threshold model with assumptions likely to overestimate risk, the lung cancer risk is estimated to be undetectably small. Risk of mesothelioma from chrysotile exposure, and risks of lung cancer and mesothelioma from amosite exposure were based on observational studies and were estimated to be even lower than that of lung cancer risk from chrysotile exposure. Academically, there are assumptions that while reasonable cannot be proven, for example, the validity of extrapolating observed risk from much higher exposures to lower exposures, estimates of individual exposure, and that there is no threshold for asbestos to cause cancer. CONCLUSIONS: The author is unaware of a similar study on long term health risks in a community exposed to asbestos in a fire. It is concluded that, using methods that do not underestimate risk, risk is undetectably small. Practical lessons from this methodology and approach to health risk assessment are discussed.