Principles for prevention of the toxic effects of metals
Book Chapter
Landrigan, PJ, Lucchini, RG, Kotelchuck, D et al. (2021). Principles for prevention of the toxic effects of metals
. 1 685-703. 10.1016/B978-0-12-823292-7.00026-7
Landrigan, PJ, Lucchini, RG, Kotelchuck, D et al. (2021). Principles for prevention of the toxic effects of metals
. 1 685-703. 10.1016/B978-0-12-823292-7.00026-7
Prevention of the toxicity of metals begins with identification of the populations at highest risk of exposure and those at greatest vulnerability to adverse effects. Industrial workers, long a principal focus of concern, remain a group at high risk due to their frequently high-level exposures. Nonoccupationally exposed populations-infants, young children and pregnant women, and the elderly-are increasingly at risk today via exposures in air, food, water, and consumer products. These nonoccupational exposures are the result of the wide and expanding environmental dissemination of metals to all regions of the world.Women, infants in the womb, and young children are highly susceptible to metals, and therefore toxic effects may occur in them at exposure levels far below those that cause adverse effects in adult workers. Elderly persons are also vulnerable, because they may have experienced a lifetime of exposure, and because of interaction between cumulative exposure and aging.The toxic effects of metals in persons of any age may be clinically evident or they may be subclinical. Some metals are necessary in small amounts to sustain human life.Occupational and nonoccupational exposures to metals are most severe in low-income and middle-income countries where mining, waste processing, and industrial development are proceeding most rapidly and occupational and environmental safeguards are often weak.Interventions to prevent exposures to metals should always be based on the "hierarchy of controls" concept, in which the first and most effective priority is to reduce exposures at source. Such reduction requires the identification, evaluation, control, and if possible elimination of the sources of exposure. In some instances, exposure reduction is achieved by changes in industrial processes or raw materials. Key elements of exposure prevention are Hazard Identification and Hazard Control are the following.Hazard Identification is a critical component of the prevention process and includes recognition of the sources and routes of exposure and elucidation of the full range of effects on health, including effects on early human development. Evaluation may involve monitoring of the workplace or general environment, biological monitoring, and/or health examinations of exposed populations. Medical examinations of high-risk populations can sometimes pinpoint reasons for increased susceptibility and guide remedial action.Hazard Control involves reduction of workplace or environmental exposures using the technologies of industrial hygiene such as engineering and environmental controls. It may also involve administrative controls, biological monitoring of exposed workers, and/or the use of personal protective equipment, but these are far less effective strategies. Elimination of an exposure at its source-termed primordial or primary prevention-is always the most effective and cost-effective mode of prevention. When prevention fails, treatment may be necessary as a last resort.Training and education of managers, workers, health professionals, policy-makers, and the general public about the health risks posed by toxic metals and approaches for risk reduction are of great importance, but can never replace direct control of exposure.To be effective, all of these programs must be supported by Authority, which is usually based in law and regulation. Such authority may involve outright bans of certain uses of toxic metals, which eliminate the exposures at source and are thus the most effective protective strategy.Great successes have been achieved over the past century in reducing the toxic effects of metals in both occupationally and nonoccupationally exposed populations. Examples include the worldwide removal of lead from gasoline, control of exposure to arsenic in drinking water in Chile, control of "black foot disease" caused by arsenic in drinking water in Taiwan, and the disappearance of "mad-hatters" disease in workers exposed to mercury. Nonetheless, much work remains to be done, and the need for increased prevention is especially great in low- and middle-income countries, where many of the world's mines, smelters, waste processing facilities, and other metals factories are located today, too often in circumstances of weak occupational and environmental controls.New hazards continue to arise and require constant vigilance. They include the proposed introduction of the manganese-containing compound, methylcyclopentadienyl manganese tricarbonyl (MMT) to gasoline supplies worldwide. In the years ahead, as demand for rare metals in 'green' technologies increases and multinational corporations continue to shift hazardous factories and toxic wastes from industrialized to developing. countries, it will be very important that these companies are required to adhere to the same environmental and safety standards in their new locations as in their former homes.Precaution should guide all decisions on whether to permit further dissemination of metals into the environment. No metal should be disseminated into the environment until its environmental fate, transport, and persistence have been thoroughly characterized and until health assessments indicate that the proposed uses of the metal are safe even for the most vulnerable members of society.
