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BMJ No 7099 Volume 315 Editorial Saturday 5 July 1997
Five years down the road from RioThe earth has not moved muchFive years ago in Rio de Janeiro the earth summit agreed on Agenda 21, a 40 chapter plan of action for achieving sustainable development. Progress has been poor, heads of state and environmental ministers heard at a special session of the general assembly of the United Nations last week,(1) but it was not all bad news. Some promising developments have occurred in international policies and agreements. And we now know more about those aspects of global change with important implications for human health: global warming, the loss of biodiversity, and persistent organic pollutants.(2-5)Global warming will probably bring extremes of weather, new infectious illnesses, threats to food production, flooding, forced migration, and a rise in sea level. Destruction of habitats and extinction of species result in the loss of materials for medical research and ecological services (such as water cleansing, pollination, and soil production) necessary for good health. Organic pollutants, particularly chlorinated hydrocarbons, may contribute to the rising incidence of reproductive disorders. Since 1992, limited progress has been made in the development of binding international agreements regarding climate change, biodiversity, and persistent organic pollutants. The parties will go to Kyoto in December to agree on quantitative targets for emissions of greenhouse gases, with the United Kingdom seeking 20% reductions of 1997 levels by the year 2010. Despite strong pressure from France and Germany, the United States will not commit to quantitative goals. Last year the United Nations Environment Programme issued the global biodiversity assessment, which provides baseline estimates of species numbers and extinction rates as well as critically reviewed methodology. Although work on the biodiversity convention is stalled, progress has been made in the convention on international trade in endangered species (CITES) and, to a limited degree, in policies on water, forests, and fisheries. Products containing chlorinated hydrocarbons, which are used in many industries, have long been recognised as dangerous to human health. These fat soluble, toxic chemicals are not easily degraded, persist for many years in the environment, concentrate up the food chain, and accumulate in animal and human tissues. Two developments have drawn renewed attention to the health risks of these persistent organic pollutants: the identification of medical waste as an important source of toxic pollution and the discovery of an extremely important new toxicological mechanism, endocrine disruption. Rachel Carson described but did not name this mechanism in her book Silent Spring, which alerted the world to the reproductive and developmental effects of pesticides on wildlife. Endocrine disrupters are chemicals that, often at extremely small doses, imitate or block hormones. They include many persistent organic pollutants, pesticides, and industrial emissions, and they have a wide range of toxic effects. The incidence of breast, prostate, and testicular cancers and male reproductive disorders, including undescended testes, have increased in recent decades. Occupational exposures to some pesticides have caused reduced sperm counts and infertility in men. It is speculated that persistent organic pollutants may be associated with the global fall in human sperm counts.(5) The children of women who have eaten food contaminated with polychlorinated biphenyls have impaired intelligence and nervous system function.(4) As long as healthcare professionals remain relatively unaware of the
health threats posed by these endocrine disrupting agents-particularly
those originating in healthcare facilities-society is unlikely to take
the actions necessary to prevent this form of pollution. Efforts to
promote good waste management practices in hospitals and healthcare
facilities, specifically reducing the use of incineration, are
critical.
The scene in the United States is particularly discouraging. The sober,
at times apocalyptic, messages of scientists at last week's meetings
were poorly covered by the press. President Bill Clinton's assertion
that "the science is clear and compelling. We humans are changing
the global climate" went virtually unreported. While acknowledging
the "real and imminent" threat of global warming to produce
drought, floods, and the spread of infectious disease, President
Clinton refused to commit the United States to reduce emissions of
greenhouse gases or to set quantitative goals for emissions of carbon
dioxide. He needs to follow the example of leaders in Britain, Germany,
and France and offer environmentally sound energy policies. Mr Clinton
is delaying hard choices by claiming that he must first educate the
American people and Congress that global environmental change is real
and dangerous. Medical, public health, and environmental communities
must hold him to his word.
Michael McCally
Professor of community medicine
Mount Sinai School of Medicine, References
1 Bennet J. Clinton defers curbs on gases heating globe.
New York Times 1997, June 27:A-1.
2 McMichael A J, Haines A, Slouff R, Kovats S, eds.
Climate change and human health. Geneva: United Nations
Environment Programme, World Meteorological Organisation, and World
Health Organisation, 1996.
3 Grifo F, Rosenthal J. Biodiversity and human
health. Washington DC: Island Press, 1997.
4 Thornton J, McCally M, Ottis P. Weinberg J. Dioxin prevention
and medical waste incinerators. Public Health Rep
1996;3(4):300-12.
5 Male reproductive health and environmental oestrogens.
Lancet 1995;325:281-5.
6 World Health Organisation. Health and environment in
sustainable development. Geneva: WHO,
1997.
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