PubMed · 9074865
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B Jirles, J Thigpen, D Forsythe. 1997. Lead in drinking water: a preventive solution.. https://doi.org/10.1289/ehp.9710515a
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Naturally occurring radioactive material (NORM) in concentrated forms arises in nature and in industry where natural radioisotopes become mobile and then accumulate at particular sites. In industry this often occurs in an acidic environment, where precipitates containing radionuclides plate out onto pipe walls, filters, tank linings, etc. As the radionuclides are selectively deposited, they build up and there is a multiplying effect in terms of the radioactivity concentration. Conditions often tend to favour the build-up of radium, particularly when barium is present and can cause the co-precipitation of radium compounds. As radium is highly radiotoxic, the handling and disposal of such material requires careful management. The state of Western Australia currently has the only low level waste repository in Australia, located at Mt Walton East. To date this repository has been used predominantly to dispose of packaged radioactive waste containing artificial radioisotopes, but there is an increasing demand for the repository to accept bulk concentrated NORM wastes from mining and related industries. Already steelwork from a dismantled phosphoric acid plant and other items contaminated with NORM have been disposed of. The Mt Walton East repository is now proposed as the disposal site for 6000 tonnes per annum of gangue residue from the processing of monazite. The residue contains thorium and a small amount of radium. This paper looks at the technical and related considerations of these disposal operations.
BACKGROUND: Pesticides, which by their nature are biologically active compounds, continue to raise public concern regarding their possible role as important etiologic agents in the development of human cancer. METHODS: To examine this potential role, the National Cancer Institute of Canada convened an Ad Hoc Panel on Pesticides and Cancer to examine the possible contribution of pesticide exposure, particularly in the general population, to the development of human cancer. RESULTS: The Panel focused primarily on exposure in the general population and reviewed a range of studies that addressed issues related to dietary exposure as well as incidental home and garden uses. In addition, the Panel examined the regulatory framework that exists to safeguard the public from potentially carcinogenic pesticides and also reviewed some potential benefits of pesticide use, including the availability of an abundant and low cost supply of fresh fruits and vegetables as an important strategy in the overall mitigation of cancer risk. CONCLUSIONS: The Panel concluded that it was not aware of any definitive evidence to suggest that synthetic pesticides contribute significantly to overall cancer mortality. The Panel also concluded that it did not believe that any increased intake of pesticide residues associated with increased intake of fruits and vegetables poses any increased risk of cancer. The Panel further concluded, among other things, that tobacco use continues to be the most important preventable cause of cancer and premature mortality and thus is an appropriate focus for cancer control strategy.
Expanding industrial and military uses of tungsten could result in substantially increased levels of this metal in the environment in the next few years. Although occupational experiences and available toxicological studies on laboratory animals suggest that tungsten may have a relatively low order of toxicity, the data are weak and inconclusive. There is a need not only for more systematic studies of the behavior and effects of tungsten in different animal species but also for a reliable, biologically realistic biokinetic model for tungsten in man that can be used to relate concentrations of this metal in environmental media to concentrations in tissues of exposed persons and translate results of experimental studies into terms of environmental exposures. This paper is intended as a first step toward development of such a biokinetic model. Information related to the biokinetics of tungsten in mammalian species is examined, a biologically meaningful compartmental model structure is proposed, provisional transfer rates between compartments are selected, areas are identified where additional biokinetic data on tungsten are most needed and suggestions are made for further research into the biokinetics of tungsten.