The coal epidemic

Abstract

Alan Lockwood's The Silent Epidemic is about coal, its use, and how its use affects our health. From the mining of coal, through its transport and burning to produce electricity, to the transport and disposal of coal wastes, each step in the lifecycle of coal is associated with hazards to health. Lockwood guides us through the world of coal, covering the chemistry and environmental fate of its combustion and byproducts, summarising pertinent epidemiology and toxicology studies, and discussing the engineering technologies, regulatory processes, cost–benefit analyses, economics, and politics that are part of the public debate on coal and energy policy. The author is adept at interpreting the specialised vocabulary of each field and providing a comprehensive but easily read introduction to one of the most pressing technological issues of our times. Numerous references to the scientific literature support each chapter, unlike so many books written in the hope of influencing policy. The story of coal begins in the ground, and Lockwood treats us to a lesson on strip mining, open-pit mining, and mountain-top removal, and on their environmental consequences. He explains the chemistry that underlies the formation and environmental fate of the principal pollutants derived from coal. These are arsenic (associated mostly with mine tailings and waste disposal), mercury (released into the atmosphere when coal is burned), sulphur oxides, nitrogen oxides, ozone, particulate matter, and carbon dioxide. The mining and transport of coal and coal wastes also produces emissions of diesel engine exhaust. Lockwood describes the various technologies for removing these pollutants from the ambient environment. He also explains the physiology of the lung and its susceptibility to disease induced by reactive oxygen species and oxidative stress. He ties the induction of oxidative stress and inflammation in the lungs to particulate matter, which can also have systemic effects on the cardiovascular system and on the brain and CNS. Lockwood summarises the evidence that air pollutants from the burning of coal are linked to respiratory diseases, among them asthma, chronic obstructive pulmonary disease, coal workers' pneumoconiosis, and lung cancer. The International Agency for Research on Cancer (IARC), for example, has classified several coal-related mixtures and processes as causes of lung cancer, including coal-tar pitch, soot, coal gasification, coke production, and indoor emissions from household combustion of coal. The IARC also has reported causal associations with skin cancer (for coal-tar pitch, soot, and coal-tar distillation) and credible evidence for associations with urinary bladder cancer (for coal-tar pitch and soot). Evidence that short-term or long-term exposure to air pollutants derived from coal, particularly fine particles with a diameter of 2·5 μm or less, is associated with cardiovascular diseases is also presented. Findings from other studies suggest that these particles, and mercury as well, might cross the blood–brain barrier and cause diseases of the brain and CNS. Lockwood cites newly emerging evidence, most reported in the past 10 years, that particulate matter could be associated with neurodegenerative diseases such as Alzheimer's disease, and that such particles and other common air pollutants derived from coal might be associated with type 2 diabetes mellitus. The book goes further, discussing evidence that links coal to global warming and its health-related effects, especially infectious diseases and malnutrition from disruption of food sources. One wonders what might have been written a half century ago had there been a similar review of another modern respiratory epidemic—tobacco. Smoking had been causally associated with lung cancer, a few other cancers, chronic bronchitis, emphysema, and coronary disease. It took decades, long after consensus was established in the scientific community that tobacco caused numerous diseases, to implement strong public health measures to reduce its use. Even now, if present smoking patterns continue, tobacco could cause a billion deaths during the 21st century. The evidence for the health effects of coal is more extensive, covering not only several cancers, respiratory diseases, cardiovascular diseases, and neurodegenerative diseases, but also mining accidents, cities made grey from coal-derived air pollution, and links to global warming. The US Energy Information Administration projects a 56% increase in the use of coal between 2007 and 2035, with 95% of this increase taking place in countries outside of the Organisation for Economic Co-operation and Development, raising concerns about environmental and occupational regulations that might be out of date, not enforced, or absent entirely. What could be the implications for the health of our children and grandchildren? A half century ago, our parents and grandparents began to educate us about the dangers of smoking. Now it's our turn to end the silence surrounding the coal epidemic. For more on coal and lung cancer see IARC. IARC monographs on the evaluation of carcinogenic risks to humans, vol 100 F—a review of human carcinogens: chemical agents and related occupations. Lyon: International Agency for Research on Cancer, 2012For more on what was known in 1954 about smoking and lung cancer see Doll R, Hill AB. The mortality of doctors in relation to their smoking habits: a preliminary report. BMJ 1954; 4877: 1451–55For more on what was known in 1964 about the health effects of smoking see US Department of Health, Education, and Welfare. Smoking and health: report of the Advisory Committee to the Surgeon General of the Public Health Service. Public Health Service Publication No 1103. Washington, DC: US Government Printing Office, 1964For more on the future health burden of smoking see Boyle P, Levin B, eds. World cancer report 2008. Lyon: International Agency for Research on Cancer, 2008For more on increasing coal use see US Energy Information Administration. International energy outlook. Washington, DC: US Government Printing Office, 2010 For more on coal and lung cancer see IARC. IARC monographs on the evaluation of carcinogenic risks to humans, vol 100 F—a review of human carcinogens: chemical agents and related occupations. Lyon: International Agency for Research on Cancer, 2012 For more on what was known in 1954 about smoking and lung cancer see Doll R, Hill AB. The mortality of doctors in relation to their smoking habits: a preliminary report. BMJ 1954; 4877: 1451–55 For more on what was known in 1964 about the health effects of smoking see US Department of Health, Education, and Welfare. Smoking and health: report of the Advisory Committee to the Surgeon General of the Public Health Service. Public Health Service Publication No 1103. Washington, DC: US Government Printing Office, 1964 For more on the future health burden of smoking see Boyle P, Levin B, eds. World cancer report 2008. Lyon: International Agency for Research on Cancer, 2008 For more on increasing coal use see US Energy Information Administration. International energy outlook. Washington, DC: US Government Printing Office, 2010 The author is an employee of the US Environmental Protection Agency (EPA). The views are those of the author and do not necessarily reflect the views or policies of the EPA.