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While many of the products of industrial processes are known toxins, it is difficult to determine how these chemicals affect public health at the levels found in the environment. To what extent does environmental pollution from industrial wastes contribute to the observed increases in, for instance, birth defects and some cancers (136)?
Studies of the adverse health effects of industrial chemicals and metals are rife with complications, as described in Linking Environment and Health. People are often exposed to a variety of environmental insults unsafe drinking water, air pollution, and tobacco smoke, to name just a few making it difficult to firmly link exposure to a specific chemical with an adverse health effect. In addition, health effects may take years or even decades to emerge (137). Finally, industrial pollution may act in concert with other threats such as malnutrition and infectious diseases to undermine health, particularly in the industrial slums of developing countries.
Despite these complications, toxicology, epidemiology, and occupational health studies are providing new insights into how industrial chemicals affect health. Studies show that health risks from industrial production can occur in three ways: direct physical injury from accidents in industrial production; acute chemical poisoning in the workplace or surrounding neighborhoods; and long-term exposure to chemicals released into the general environment.
Physical injury and chemical poisoning generally fall within the field of occupational health, and their health impacts are relatively well understood. Since the 1700s when Sir Percival Pott first established a link between chimney sweeps and a higher incidence of scrotal cancer, occupational exposures to hazardous chemicals provided initial warning of potential harm to the wider public. They remain a serious problem today.
The health impacts of chronic, long-term exposures are less clear. Until recently, most of the concern surrounding possible links among chemicals and long-term health effects has focused on cancers. Although numerous examples have linked occupational exposures with specific types of cancer, such as asbestos with malignant mesothelioma, it is unclear to what extent environmental exposures to chemicals contribute to the overall cancer rate (138).
Concern now encompasses other health effects as well, such as damage to the immune, nervous, and reproductive systems. Recent evidence suggests that a variety of chemicals, including PCBs, dioxins, pesticides, and heavy metals, can compromise the immune system. The immune system plays a crucial role in protecting the body from viruses, bacteria, and other invaders (139).
Although the health effects emanating from exposure to these chemicals are likely to be small compared to the toll exacted from factors such as smoking, diet, and infectious disease, concern is nonetheless warranted. Industrial chemicals can persist in the environment for many decades and accumulate in marine and terrestrial food chains, thus posing health risks years after these chemicals are no longer used. Evidence also suggests the effects of exposure to toxic substances could be transgenerational. Medical history also shows that caution is appropriate; some chemicals, such as asbestos and PCBs, were used for years before they were found to cause adverse health effects.
The range of industrial processes, industrial wastes, and possible health impacts is too vast to cover in this chapter. Instead, this section focuses on two categories of ubiquitous pollutants persistent organic pollutants (POPs) and heavy metals to illustrate the various sources, routes of exposure, and possible health impacts resulting from exposure to industrial pollutants. In particular, this section examines the health effects of PCBs and lead in the environment. The chapter then looks at how industrial chemicals can affect human health in unsuspected ways through global ecological disruption, by looking at chlorofluorocarbons (CFCs) and the health consequences of ozone depletion. Air pollution, to which industrial production contributes significantly, is discussed in the next section, Rising Energy Use.
136. A.B. Miller, “Review of Extant Community-Based Epidemiological Studies on Health Effects of Hazardous Wastes,” Toxicology and Industrial Health, Vol. 12, No. 2 (1996), p. 226.
137. Ibid, pp. 226-227.
138. Kate Cahow, “The Cancer Conundrum,” Environmental Health Perspectives, Vol 103, No. 11 (November 1995), p. 999.
139. Krzysztof Krzystyniak, Helen Tryphonas, and Michael Fournier, “Approaches to the Evaluation of Chemical-Induced Immunotoxicity,” Environmental Health Perspectives, Vol. 103, Supplement 9 (December 1995), p. 17.