Asthma Now Hits One in 10 Children, study says

Fourfold Increase Linked to Air Quality

By Martin Mittelstaedt
Friday January 27, 2006
The Globe and Mail

The rate of childhood asthma in Canada has soared fourfold over the past 20 years, to a level where more than one out of every 10 children is now diagnosed with the respiratory illness, says a report by North America’s environmental watchdog agency.

“Asthma is one of the most prevalent chronic conditions in Canadian children and is also a serious problem in adults,” says the report, written in part by federal government researchers. It is the first study on the health of children in Canada, the United States and Mexico.

The data collected in the three countries show asthma to be prevalent across the continent. The report says the disease, immediately recognized by the wheezing and chest pain it causes, is “the most common chronic disease of childhood in North America.”

Based on population figures, the study’s conclusions indicate that about one million children in Canada have or have had asthma.

The highest rate of asthma presented in the report was among Canadian boys aged 8 to 11, of whom a staggering 20 per cent were diagnosed with the disease in the late 1990s. In the United States, about 13 per cent of children had asthma at some point in their lives, according to figures compiled in 2003.

The report, from the Montreal-based Commission for Environmental Co-operation, said the huge increase in asthma means the disease has become a “tremendous human and economic burden for millions of children and adults.”

While researchers do not know the exact cause of asthma, whose main symptom is a chronic inflammation of the lungs leading to difficulty breathing, the report said the illness is linked to indoor and outdoor air quality.

Both have a greater effect on youngsters than adults.

“Children are especially sensitive to air pollution because of their rapid growth, developing body systems . . . and higher intakes of air,” it says.

The report says exposure to second-hand tobacco smoke and dust mites indoors are risk factors, while pesticides, the fumes given off by some plastics, and volatile organic compounds in solvents and other chemicals may also play a role.

Research scientist Teresa To at Toronto’s Hospital for Sick Children said indoor air is being assessed as a risk factor because children spend about 80 per cent of their time inside.

She said the extremely high asthma rate in boys just before their teenage years has also puzzled researchers, who have not yet determined what makes them more susceptible to the disease.

Dr. To said one hypothesis is that boys in that age range play more aggressively than other children, and if they are prone to wheezing, heavy exercise might exacerbate the condition, leading to an asthma diagnosis.

Some children who are diagnosed with asthma grow out of the ailment.

Ingredients in outdoor air pollution that are suspected in asthma include ground-level ozone and small particulates, two of the most dangerous components in smog, the report says. Those have not been reduced in Canada since the mid-1990s.

The report also warns that about a quarter of Canadian residents live in homes built before the 1960s and may be exposed to excessive levels of lead, once a common ingredient in paint.

Health Canada is about to sample lead levels from about 5,000 people to see if there is a cause for concern.

The rates of several types of cancer have been rising rapidly among young adults, and the report says the trend may be related to childhood exposures to environmental hazards.

Among the cancers rising “significantly” in young Canadian adults are thyroid cancer, which has been linked to exposure to medical X-rays; melanoma, blamed on sun exposure early in childhood; testicular cancer, for unknown reasons, and non-Hodgkin’s lymphoma, for which there are possible environmental factors.

Although the report doesn’t mention any of these factors by name, researchers have been studying pesticides and hair dyes for a link to lymphoma.

Among its other findings, the report notes that Canadian women are delaying having children, and that a drawback to this approach is that older women have had a longer time to absorb environmental chemicals from occupational and other exposures.

Children born to these women “potentially have greater exposures to contaminants in utero” because of these pollutants, the report says.