PubMed · 8909615
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P G Tuteur. 1996. Question to answer requires valid data.. https://doi.org/10.1002/(sici)1097-0274(199611)30%3A5%3C642%3A%3Aaid-ajim14%3E3.0.co%3B2-3
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Pollution from abandoned mines is a serious, widespread and increasingly common cause of surface water degradation in the LOIS study region. Indeed, in some areas of the UK it is now the single greatest cause of freshwater pollution. Remediation of such pollution in the long-term is probably best achieved by passive treatment, which has the advantage of concentrating expenditure in capital costs, with only modest financial commitments for long-term maintenance. To plan such remediation, however, it is important to have an understanding of the physical and chemical processes governing pollutant release over scales of many decades. By analysing water quality records for major abandoned mine discharges in Scotland, Wales and Cornwall, long-term acidity generation is shown to have two components: "vestigial' and "juvenile'. The vestigial component relates to the geochemical trauma which occurs as abandoned mine voids are allowed to fill with water for the first time, taking ferrous and ferric hydroxysulphate salts (intermediate products of pyrite oxidation) into solution. Dissipation of vestigial acidity is primarily controlled by the hydraulic retention time of the flooded mine system, and will generally be accomplished in less than 40 years. Juvenile acidity arises from on-going pyrite oxidation in the zone of water table fluctuation within the mined system, and can be expected to continue for many hundreds of years, until the supply of pyrite is finally exhausted. Rational planning for the remediation of minewater pollution should be based on intensive treatment of discharges while the vestigial acidity is being depleted, followed by long-term passive treatment of the juvenile acidity.
Toward the end of the 1920s, technical advances in mining led to an increase in airborne burdens of dust in the South Wales coal mines. This coincided with a dramatic increase in the incidence of disability and death from respiratory disease among the miners. For their condition to be compensable, claimants were required to have worked with rock containing more than 50% 'free silica.' Dr W.R. Jones, a mining geologist, was asked to help obtain compensation for those claimants who could not satisfy the 'free silica' condition. He was unable to identify high-silica rocks where none had been said to exist. He did however, successfully argue the brief against the eminent Professor J.S. Haldane (who was the dominant authority, having had lengthy experience in the field of health and mining), for the fibrous form of sericite being commonly the important agent responsible for pneumoconiosis. As a consequence, the category of miner eligible for compensation was broadened. Evidence was gathered worldwide that supported the hypothesis that silicates and not just crystalline silica could cause pneumoconiosis. Despite the suspicions raised about the special power of mineral fibers during this public debate, some 40 years were to elapse before potential health hazards from fibers other than asbestos were to be taken seriously and investigated.
The ILO classification of small and large opacities is the basis for the compensation of patients with pneumoconiosis. In order to validate the radiological findings, we compared the ILO classification with the gradings of pneumoconiosis in the post mortem investigation (n = 126). An ILO classification of 1/0 used as the threshold value for accepting the diagnosis of a pneumoconiosis was 100% sensitive with a specificity of 2%. With a value of 2/3 the sensitivity decreased to 60% and specificity increased to 74%. The grading of large opacities in the radiograph correlated well with the post mortem findings (rs = 0.71; p < 0.001). For accepting the diagnosis pneumoconiosis from the radiograph alone a threshold value of 1/0 is not specific. The ROC-plot revealed that specificity reached acceptable levels with an ILO classification of at least 2/3.