Illness in the air: how pollution causes heart disease and cancer

Michele Chase, 28, has suffered from smog-related health problems for as long as she can remember. At just two years old she developed asthma and spent her early Mississauga, Ont., childhood coughing and wheezing from industrial pollutants and traffic fumes. Finally, when she was nine, her family moved to a small community near Fredericton.

"In Mississauga, it was hard to get a full breath of air on a regular summer day. I noticed a big difference when we moved to New Brunswick," says Michele. She could finally control her asthma. When she returned to Ontario to visit relatives in the summer, "I had to go to emergency a few times because of asthma attacks," she says.

While the most obvious effects of pollution are chronic lung conditions, such as asthma and chronic obstructive pulmonary disease (COPD), the complex mix of chemicals in environmental contaminants is also a significant contributor to all the major diseases that kill human beings: heart disease, stroke, lung conditions and cancer.

Today's pollution is already affecting the health of the next generation. And because they are created by fossil-fuel combustion in vehicles and power plants, pollutants are hard to avoid. 

The heart breaker
The 2008 Heart and Stroke Foundation Report Card on Canadians' Health is one of many sources showing that it's fine particles in the air -- tiny toxic compounds 30 times thinner than a human hair -- that have the most devastating impact on human health.

Each year in Canada, exposure to environmental contaminants causes up to 11,000 deaths, up to 67,000 hospitalizations and 580,000 days in hospital as a result of heart disease. This includes heart attacks, sudden death from arrhythmia (irregular heartbeat) and premature death from congestive heart failure and stroke.

In 1993, Harvard University's Six Cities study, which followed more than 13,000 people for about 15 years, found that the overall death rate was 26 per cent higher in Steubenville, Ohio, the most polluted U.S. city in the study, than in Portage, Wis., the least polluted. Of all air pollutants, fine particle levels were most closely linked to death rates. Scientists were surprised that there were many more pollution-related deaths from heart disease than from other causes, such as lung disease.

The Harvard study led the U.S. Environmental Protection Agency to establish more stringent air quality standards in 1997. An eight-year follow-up study, published in 2006, found that the death rate from heart disease plummeted after fine particle levels dropped.

Location, location, location
Another large-population health study, this time of 65,000 women, published in 2007 in the New England Journal of Medicine, found that in cities with higher levels of pollution -- or in more polluted areas within a city -- women had higher death rates from both heart attack and stroke.

In fact, the harmful effects of fine particles on arteries, blood vessels and heart rhythms can be measured almost immediately. In a University of Toronto study, healthy young people inhaled fine particles, plus ozone, for two hours. Tests showed constriction of their blood vessels. In people with heart disease, these effects can trigger a heart attack.

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A 2005 University of Southern California study showed that people living in more polluted areas of Los Angeles have thicker neck arteries than those living in less polluted areas, in part because the arteries are often constricted, putting people at risk for stroke.

A 2005 Harvard School of Public Health study revealed that implanted defibrillators detect more severe heart-rhythm disturbances when air pollution levels are high.

Invisible attackers
Not only can pollution cause a heart condition, but smog also makes people with congestive heart failure gasp for breath. A McGill University study found that patients with congestive heart failure take in less oxygen on more polluted days.

"If the air pollution is higher, less oxygen comes into the bloodstream. Anything disruptive in the environment can get them into trouble," says Dr. Nadia Giannetti, a cardiologist at McGill University Health Centre in Montreal and coauthor of the study.

One of the worst contributors to fine-particle pollution is diesel exhaust. Construction equipment is a major source of diesel particulate in urban areas, says Michael Brauer, an epidemiologist at the University of British Columbia in Vancouver, noting that reducing diesel emissions from such machines, as well as buses and trucks, could help to save lives.

While governments will have to improve standards for vehicles and industry, you can try to protect your heart by limiting your exposure to heavy traffic when exercising and driving, and by choosing a healthier place to live.

The breath taker
Environmental pollutants, such as ozone and fine particles, make life miserable for 2.7 million Canadians with asthma and more than 1.5 million with COPD. (COPD is made up of two lung diseases, chronic bronchitis and emphysema, that cause lung damage and obstruct airflow in the lungs.) Fine particles can evade the body's natural cleaning and repair system in the lungs.

While larger particles are trapped and cleaned out by sticky mucous and tiny hairs (cilia) lining the insides of the breathing tubes in your lungs, fine particles are too tiny to be trapped and expelled. They drift all the way down to the tips of the lungs and collect in the alveoli (tiny air sacs that deliver oxygen to the bloodstream). And that means reduced lung capacity. "The smaller the particles, the deeper the penetration," says Kenneth Maybee, the Canadian Lung Association's chair for environmental issues, noting that the particles can irritate, inflame or permanently damage lung tissue.

In essence, inflammation from prolonged exposure "can lead to a remodelling of the airways, so you get structural changes in the airways, making them thicker and narrower," says Brauer.

The impact of environmental pollutants on the respiratory health of Canadians is huge. Each year in Canada patients with COPD spend 1.7 million days in hospital and nearly 10,000 die. Environmental contaminants cause up to 3,000 deaths and 500,000 days in hospital for Canadians with COPD. Each year Canadians with asthma spend up to 58,000 days in hospital and suffer as many as 1.9 million restricted activity days as a result of environmental exposures.

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The cancer trigger
Exposure to environmental contaminants causes many different types of cancer, contributing to as many as 10,000 deaths and 24,000 new cases of cancer in Canada each year.

The WHO's International Agency for Cancer Research has identified about 400 agents known to be carcinogenic or potentially carcinogenic to humans. Some of the known environmental carcinogens include asbestos, radon, arsenic, fine particles, polycyclic aromatic hydrocarbons (PAHs), benzene, formaldehyde, solvents, some paints and dyes, dioxins, PCBs and pesticides. Many studies have linked specific contaminants to particular types of cancer.

The Canadian Cancer Society and Cancer Care Ontario reported in 2005 that water disinfection byproducts had been linked to bladder cancer; pesticides to non-Hodgkin's lymphoma; fine particles and PAHs in diesel exhaust to lung cancer; arsenic to lung, skin and bladder cancers; and extremely low-frequency electromagnetic fields to childhood leukemia.

What scientists don't know for sure is how safe long-term exposure to supposedly "low" levels of toxic chemicals is. We don't know the dangers of wearing clothes treated with carcinogenic brominated flame retardants, applying cosmetics that contain formaldehyde or eating poultry that contains trace levels of arsenic that was added to chicken feed, all substances flagged by the WHO but still widely available.

Better safe than sorry
As a society and as individuals, the best way to prevent cancers relating to environmental exposures is to err on the side of caution, even when cause-and-effect relationships have not been proven conclusively. For example, regulators should take steps to reduce exposure to probable carcinogens such as diesel emissions, says Ray Copes, medical director of environmental health services at the B.C. Centre for Disease Control in Vancouver. Diesel exhaust from trucks, buses and construction equipment, Copes points out, is a major source of fine particle pollution, PAHs and benzene.

But you can also take steps as an individual. Know what consumer products may have carcinogenic properties and avoid or limit your exposure to them; for example, certain air fresheners contain potentially carcinogenic benzene compounds. And the Canadian Cancer Society advises that heating cookware with nonstick coatings at high temperatures can create fumes that contain a suspected cancer-causing chemical tetrafluoroethene.

Use environmentally friendly cleaning products that don't release volatile organic compounds. Avoid using pesticides on your lawn or garden. Prepare food to minimize ingestion of toxic chemical residues. For example, "You can reduce your exposure to dioxins and PCBs by preparing meat so that fat drains away," says Copes. "People have more control than they realize over their personal environment. If you spray the area around your head with an aerosol, that source may be more important than a large smokestack five kilometres away."

It's worth noting that Canadians are more inhibited in making good choices than Europeans are, because we are not being fully informed about carcinogens in consumer products. In the European Union, as well as in California, community right-to-know legislation requires manufacturers to list carcinogens on product labels.

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The effect on your heart
Scientists are now learning how fine particle pollutants trigger heart attacks and strokes. "If you inhale lots of particles, specialized cells in your lungs call for help and make inflammatory chemicals that get into the bloodstream and react on the surface of blood vessels. If that happens, blood vessels have more leaks and cholesterol penetrates into blood vessels and builds up in the blood vessel wall," leading to hardening of the arteries, explains Dr. Stephan van Eeden, a respirologist in Vancouver.

Other studies have shown that the inflammatory response to particle pollution sends chemicals into the bloodstream that may increase clotting, disrupt heart rhythm, increase the heart rate and raise blood pressure.

Killer cars
Living close to heavy traffic can be lethal. A 2004 McMaster University study found that people in Hamilton who lived within 50 metres of a major highway or 100 metres of a congested city road died 2.5 years earlier than those who didn't.

Pollution from traffic may also trigger the onset of childhood asthma. A 2007 study by Michael Brauer, an epidemiologist at the University of British Columbia in Vancouver, found that young children in the Netherlands living close to busy road had a 20 to 30 per cent increased risk of developing asthma. Brauer and his team measured children's exposure to nitrogen dioxide, fine particles and soot from diesel emissions. He followed the children from the second trimester of their mother's pregnancy to the age of four. "The study shows the importance of reducing exposure levels in early infancy and even during pregnancy," he says.

Although smoking is the leading cause of COPD, exhaust from cars and trucks can permanently damage lung tissue and cause nonsmokers to develop this chronic, incurable condition. A 2005 German study found that women who lived close to busy roads and had long-term exposure to pollution were more likely to develop COPD. "Women tend to develop more COPD from air pollution than men," says Dr. Stephan van Eeden, a respirologist in Vancouver.

Click to continue to discover how pollutants harm our children's health before they're born…

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Pollution and prenatal problems
Mounting evidence suggests that environmental contaminants may also contribute to a wide range of reproductive health problems, endangering the next generation.

Exposure to high levels of air pollution is linked to lower birth weights and pre-term deliveries; these babies are then at greater risk of neurological problems, infections and heart ailments.

Reproductive toxicants can be found in drinking water, food, soil, air and, unfortunately, our bodies. A 2005 Environmental Working Group report found, on average, more than 200 industrial chemicals in the umbilical cord blood of newborns in the United States, including traces of 21 pesticides. Of the 287 different chemicals detected, 208 caused birth defects or abnormal development when tested on animals.

Researchers believe chemicals may affect the weight of the unborn child directly through the placenta, by causing poor nutrient or oxygen supply. Each year in Canada, prenatal exposure to environmental contaminants is associated with as many as 2,500 low-weight births. "When a baby is born too small, there are many health risks that could carry on later in life," says Linda Dodds, an epidemiologist in the department of obstetrics and gynecology at Dalhousie University in Halifax.

Studies by Dodds and Will King of Queen's University in Kingston, Ont., have found higher rates of stillbirths in women exposed to high levels of chlorination byproducts in drinking water. Congenital anomalies have also been linked to contaminants including lead and nitrates in drinking water, solvents, pthalates, pesticides and ethanol.

This past November, our federal government announced a $3.9-million research study to track chemical pollutants in about 2,000 pregnant women and their babies. One of the goals of the study is to see if environmental contaminants are having harmful effects on fetal development and on infants after birth.

This article was first printed in the April 2008 issue of Homemakers Magazine. Click to subscribe online and never miss an issue.

Cleaner air and a cleaner earth start in your home. Check out our 9 pollution solutions for tips on how you can be more earth-friendly -- for everyone's sake!

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