Environment

Canadians consume more and more

"Only two things believe in growth forever: the economy and cancer cells," says Canada’s best-known environmentalist, David Suzuki. In the last 40 years, the average Canadian family size decreased by 50%, while the average size of a house doubled. "If everybody in the world lived the way we do in Canada," Suzuki said, "we would need the resources of 5 more planets." Suzuki was speaking at the Sixth Canadian Conference on International Health in November 1999. CMAJ 2000;162(5):687-8.

Environmental endocrine disruption

Endocrine-disrupting chemicals are ubiquitous in the environment. Longer-lasting representatives, such as DDT, PCBs and dioxins, are detectable in nearly all human blood samples. Two American researchers describe the potential health implications of exposure to endocrine-disrupting chemicals. Exposed animals show effects including altered sexual behaviour, birth defects and compromised fertility. Human surveillance-based studies have shown increases in some potentially hormone-related conditions. The fetus is particularly sensitive to hormonal fluctuations. Cohort studies involving children exposed in utero to PCBs have shown delayed psychomotor development and increased distractibility among those most exposed. Many endocrine-disrupting chemicals are targeted for elimination, but some are still in commercial use. Political decision-making is hampered by scientific uncertainty. The medical community can play a critical role in evaluating the data, educating the public and protecting future generations. CMAJ 2000;163(11):1471-6.

Global climate change and health

In the second article in the CMAJ series on environment and health, researchers examine the impact of global warming on world health. Direct effects include morbidity and mortality from heat waves, drought, floods, storms and the breakdown of systems in the aftermath of weather disasters. Indirect effects include decreased crop productivity owing to pests and climate change, changing water availability, lower air quality, rising sea levels and animal-based diseases appearing in regions in which they had previously been unheard of. The authors warn that these effects may no longer be entirely avoidable but conclude that physicians should still advocate for reductions in fossil fuel combustion, among other environmental improvements. "Although there is much that is unavoidably complex and uncertain about these large-scale risks to human population health, the case for health professionals urging a health-protecting, precautionary approach that will have multiple benefits remains clear," conclude the authors. CMAJ 2000;163(6):729-34.

Halifax says No to pesticides

With a strong show of hands at city hall — 17 to six — Halifax became the first major city in Canada to ban the use of pesticides on residential lawns and gardens. The full ban takes effect in 2003. CMAJ 2000;163(9):1180.

Ozone depletion and ultraviolet radiation

Researchers find that overall compliance with international agreements on phasing out ozone-depleting substances has been good, but there is no reason for complacency. As the production of the bulk of such substances in developed countries is curbed, other sources become more important. These other sources may prove to be more difficult to phase out; for example, the production and replacement of ozone-depleting substances can be difficult to control in some developing countries because there is no suitable infrastructure or international support to overcome the locally prohibitive costs for the required changes. Consumers in developed countries should remain vigilant and not purchase anything operating or produced with ozone-depleting substances when good alternatives are available. CMAJ 2000;163(7):851-5.

Population, consumption and human health

According to the most conservative realistic projection of fertility rates, the world population is estimated to increase to 9.5 billion by 2100. In the developing world, high fertility rates correlate with poor population health, environmental degradation, and high perinatal morbidity and mortality. Education, particularly of women, and access to family planning are rewarded by declining fertility rates and improved community health. In the developed world, high consumption contributes to pollution, environmental degradation and global warming. Political and economic reform will be needed to transform unsustainable to sustainable production, and provide a model for developing economies. CMAJ 2000;163(5):551-6.

"To protect the health of populations we must develop systems of food, energy and industrial production that can be sustained over generations," writes the Environment and Health series editor Dr. McCally. "Finding solutions to the threats posed by environmental change is the major health challenge of the next century." CMAJ 2000;163(5):533-5.

The environment and cancer

Current estimates attribute five% of cancer deaths to occupational factors and two% to environmental pollution. In terms of the estimated lifetime risk of any cancer (currently 40% for men and 35% for women) this represents a substantial burden of disease. In the fourth article in the CMAJ series on Environment and Health, a physician reviews the relationship between environmental exposure and cancer, its implications for cancer prevention and the physician’s role in screening for hazardous exposure. CMAJ 2000;163(8):1009-12.

War and its aftermath

War rivals infectious disease as a global cause of morbidity and mortality, not only during active fighting, but also as a consequence of the destruction of infrastructures and the environment, the displacement of populations and the ongoing presence of radioactivity, weapons and toxins. Four wartime activities have a prolonged and pervasive impact on the environment: nuclear weapons production and testing, aerial and naval bombardment, dispersal and persistence of land mines and military ordnance, and the use and storage of military despoilants, toxins and waste. A Harvard physician surveys the scale and impact of military activities on the environment and human health and concludes that much still needs to be understood about the destructive potential of war on ecosystems. CMAJ 2000;163(9):1157-61.

World water crisis in the offing?

The world is facing a critical shortage of fresh water in the next 20 years, according to a report from the World Commission on Water. The report, A water-secure world: vision for water, life and the environment, predicts that the use of water will increase by 40% in the next two decades due to growing demands from agriculture, industry and urban areas. The commission, whose sponsors include the World Bank and UN, was created to recommend ways to achieve global water security. Many countries will be looking to Canada for help, since it is to fresh water what Saudi Arabia is to oil. CMAJ 2000;163(7):868.

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