Health and the environment

Portrait of David Suzuki

SCIENCE MATTERS by David Suzuki

• Preventing illness is the best way to get healthcare costs down. So why aren’t governments doing more to protect the environment? We’ve long known environmental factors contribute to disease, especially contamination of air, water and soil. Scientists are now learning the connection is stronger than we realized.

New research shows 60 percent of emerging infectious diseases affecting humans – those that rapidly increase in incidence or geographic range – starts with animals, two thirds from wild animals. Lyme disease, West Nile virus, Ebola, SARS and AIDS are just a few of the hundreds of epidemics that have spread from animals to people. A study by the International Livestock Research Institute concludes more than two million people a year are killed by diseases that originated with wild and domestic animals. Many more become ill.

According to an article in the New York Times, “Emerging diseases have quadrupled in the last half-century.” The increase is mainly due to human encroachment into wildlife habitat and its destruction. For example, one study concluded a four percent increase in Amazon deforestation led to a 50 percent increase in malaria because mosquitoes, which transmit the disease, thrive in the cleared areas.

Another example from the article shows how interconnected life is. Development in North America has destroyed or fragmented forests and chased many predators away. This has led to a huge increase in white-footed mice, which carry Lyme bacteria. The mice are not good at removing ticks and their larvae and so the ticks pick up bacteria from the mice and spread it to other mammals, including humans. Because the number of Lyme-infected ticks has multiplied, more are transferring the disease to humans.

Global warming is adding to the problem. A study in the journal Nature, “Impact of regional climate change on human health,” notes heart attacks and respiratory illness, due to heat waves, altered transmission of infectious diseases and malnutrition from crop failures can be linked to a warming planet. Research has also shown that warming ocean waters are increasing the incidence of waterborne illnesses, including those caused by toxic bacteria in shellfish.

The World Bank estimates a severe influenza pandemic could cost the world economy $3 trillion. Environment Canada says air pollution alone costs the Canadian economy billions of dollars a year.

A key solution, according to One Health Initiative, is to look at the links between human, animal and ecological health and to manage our activities in a sustainable and holistic way. The US-based initiative is bringing experts in human, animal and environmental health together to study these links. Another promising area of research is natural capital evaluation. Forests and green spaces filter water and store carbon. Urban green spaces provide cooling and protection from storms. And ecosystems in balance help protect us from disease outbreaks.

With the world’s human population now at seven billion and growing and the demand for technology and modern conveniences increasing, we can’t control all our negative impacts. But we have to find better ways to live within the limits nature and its cycles impose. Our physical health and survival and the health of our economies depend on it.

Written with contributions from David Suzuki Foundation Editorial and Communications Specialist Ian Hanington. Learn more at www.davidsuzuki.org

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