Armley asbestos disaster
The contamination was the result of the activities of a local asbestos factory, part of the Turner & Newall (T&N) group (often referred to by the name of its founders, J. W. Roberts Ltd.) and occurred between the end of the 19th century and 1959 when the factory eventually closed. At its peak the factory had 250 employees. At least 300 former employees are believed to have died from asbestos-related illnesses, and a number of cancer deaths in the Armley area were traced to the factory in 1988 as a result of an investigation by the "Yorkshire Evening Post". The estate was found to have the highest incidence in the country of mesothelioma. As the interval between exposure and diagnosis can be up to 50 years the number of further deaths which may occur due to the factory's emissions or residual dust since its closure cannot be predicted.
Mesothelioma
Asbestos was known in antiquity, but it was not mined and widely used commercially until the late 19th century. Its use greatly increased during World War II. Since the early 1940s, millions of American workers have been exposed to asbestos dust. Initially, the risks associated with asbestos exposure were not publicly known. However, an increased risk of developing mesothelioma was later found among naval personnel (e.g., Navy, Marine Corps, and Coast Guard), shipyard workers, people who work in asbestos mines and mills, producers of asbestos products, workers in the heating and construction industries, and other tradespeople. Today, the official position of the U.S. Occupational Safety and Health Administration (OSHA) and the U.S. EPA is that protections and "permissible exposure limits" required by U.S. regulations, while adequate to prevent most asbestos-related non-malignant disease, are "not" adequate to prevent or protect against asbestos-related cancers such as mesothelioma. Likewise, the British Government's Health and Safety Executive (HSE) states formally that any threshold for exposure to asbestos must be at a very low level and it is widely agreed that if any such threshold does exist at all, then it cannot currently be quantified. For practical purposes, therefore, HSE assumes that no such "safe" threshold exists. Others have noted as well that there is no evidence of a threshold level below which there is no risk of mesothelioma. There appears to be a linear, dose-response relationship, with increasing dose producing increasing risk of disease. Nevertheless, mesothelioma may be related to brief, low level or indirect exposures to asbestos. The dose necessary for effect appears to be lower for asbestos-induced mesothelioma than for pulmonary asbestosis or lung cancer. Again, there is no known safe level of exposure to asbestos as it relates to increased risk of mesothelioma.