Asthma: a costly epidemic from unclear sources
The health of humans and the health of the natural environment are the two sides of the same coin. The saying could not ring more true to Robert F. Kennedy Jr. : three of his six children have asthma, explained the American environmental lawyer, speaking at an Asthma Society of Canada fundraiser, late October 2006 in Toronto.
“We don’t know what the causes of asthma are. But we know what triggers asthma attacks. It is bad air”, said Kennedy, the author of “Crimes against Nature”, published in 2004, and an eloquent advocate of free-market environmental economics.
In Canada, asthma stands out as a rampant and costly epidemic growing under the radar and affecting both children and adults. In 1990, asthma cost up to 648 million $ in 1990 and possibly over $ 1 billion in 1998.
In 2000 alone, close to half a million Canadian children suffered from asthma, according to Statistics Canada (485 700 children ages 4 to 11 or 15.6%). In 2005, 8.3 % of adults lived with asthma (2,249,000 aged 12 and over) reports Stats Can (while similar data for children are not available.)
In short, close to one in ten Canadians were suffering from physician-diagnosed asthma in 1998/1999 (10.7 % of children under 19 and 7.5 % of adults, for a total of about 2.5 million Canadians or 8.2 %).
According to the Asthma Society of Canada, in a new report to be published next spring (“Air Pollution, Human Disease and the Costs in Canada”), “the prevalence of asthma among children aged 0 to 14 years increased from 2.5% in 1978 to 11.2% in 1995. Data from 1998/99 indicate that the prevalence has leveled off at the higher value.”
Asthma, an overblown allergic reaction
Technically speaking, asthma is an abnormal allergic reaction to indoor or outdoor substances. “With an asthmatic, it is some kind of a chemical entity that is a trigger. It all depends on where the chemical resides : indoor or outdoor”, says Dr. Ted Boadway, health policy consultant and former executive director of health policy of the Ontario Medical Association.
In other words, one’s body defense mechanism, the immune system, is over-reacting. Imagine, in the case of a fire in a city, instead of a few firemen and their trucks, the emergency response authorities would be sending a large squad of riot police in full gear, and you have asthma.
This blown-out allergic response causes the airways to narrow, through inflammation or contraction of the lung’s bronchial tubes, causing wheezing, cough, chest tightness or shortness of breath.
“Occasionally, the symptoms become so severe as to interfere with normal activities, such as exercise, sleep and speech,” reads The Prevention and Management of Asthma in Canada, a National Asthma Control Task Force report published in 2000.
Unkown causes vs. known triggers
The traditionally accepted view pleads that the exact causes of asthma are not known, making this chronic condition difficult to prevent. So the focus is on management, i.e. medication mainly and some environmental control.
Genetic predisposition, i.e. susceptibility, would contribute to developing asthma, the widely accepted theory goes. Then “triggers” in the surrounding environment would lead to the abnormal immune reaction. These triggers come in two flavours, reads the mainstream understanding of asthma: causal and contributing factors.
The “causal factors” may prime (i.e. “sensitize”) the airways. They include cat and other animal dander, dust mites, cockroaches, workplace contaminants. They can combine with “contributing factors”, which may include cigarette smoke during pregnancy and childhood, respiratory infections, and indoor and outdoor air quality (air pollution).
So currently, asthma management strategies tend to focus only downstream, that is after the fact, once a person’s body has already been sensitized or to reduce substances that could sensitize the immune system. Medication is usually used to open-up the airways as a last resort.
But the question remains: why would a person’s immune system send a riot police armoured vehicle instead of a fire truck to put out a fire?
Indeed, focusing on the triggers and environmental sources of asthma might be the tree that is actually hiding the forest, according to some voices pointing to the root causes of this abnormal immune reaction.
Indeed, shouldn’t the real question be: “Why is the immune system reacting so abnormally violently in the first place?”.
“Absolutely”, replies Frank Viti, CEO of the Asthma Society of Canada (ASC). “We are decades behind [other diseases such as diabetes] in terms of prevention. We need to do more. It is a disgrace”, says Viti, an MBA graduate at the helm of the ASC for three years and suffering himself from asthma.
A respiratory care revolution needed in Canada
Viti calls for no short of a “respiratory care revolution” nation-wide. While the outdoor pollution link to asthma needed to be documented - leading to next spring’s ASC report, Frank Viti confirms intentions to turn to research on the causes of asthma.
On the public authorities side, Health Canada simply announces an updated version of its Respiratory Disease in Canada
report (due out in the Fall of 2007). The Public Health Agency of Canada says it has recently established an External Advisory Committee “to provide ongoing expert advice on respiratory surveillance activities, including asthma.”
However, back in 2000, the Canadian National Asthma Control Task Force already had provided public authorities with serious indications about the sources of asthma.
“The increase in asthma seen among children in westernized countries in the past several decades may be the result of alterations in the nature of exposures to various factors in the fetal and early childhood period, which may, in turn, influence the development of the immune system.”
This task force report The Prevention and Management of Asthma in Canada also mentions breastfeeding as potentially reducing the incidence of asthma (see sidebar), while summarizing vaguely: “ In genetically predisposed individuals, the altered immune system may result in an increased allergic response to foreign substances, and this may predispose the child to asthma.”
To explain why the immune system might be “altered”, several avenues are actually being already seriously considered, including early childhood diet, excessive hygiene practices and antibiotics use, as well as occupational health hazards for the adults [see Sidebars].
Food, excessive hygiene, indoor pollutants?
The combination of genetic predisposition and the vast diversity of environmental factors creates a significantly complex equation to solve, in order to adequately explain and prevent the onset of asthma.
“There is no magic answer. It is a thousand things, each of which need to be attended to,” acknowledges Dr. Ted Boadway, who coordinated the Illness-Cost of Air Pollution in Ontario study (which is currently being expanded Canada-wide, with results expected within a year.)
“It is an area where it does not seem we have all the answers”, agrees Dr. Noel Kerin, Occupational Medicine expert, based in Toronto. “It is a combination of susceptibility, that is genetic predisposition and of degree of exposure to allergens”, sums up Dr. Luciuk, consultant in Allergy and Clinical Immunology, who recently gave a seminar to the BC Lung Association in Kelowna, highlighting the link between allergy and asthma.
“Environmental control is number one,” says the Richmond, BC, physician. “Medication is second, but not necessary if environmental control can work.” Dr. Luciuk adds: “Air pollution is a good irritant, especially sulfur oxides and can cause more severe allergic reaction.” (Not mentioning cardiovascular problem in the ageing population from air pollution.)
In the end, the asthma equation is obviously not simple to solve, but targeting equally all the different parameters should be a priority, be it in the baby bottle or on the plate plate, in the home, at work or outdoor, including “bad air” – the latter causing a plethora of other harmful and costly health effects (in Ontario alone - 12.5 million out of the 32.3 million Canadians - the Ontario Medical Association has calculated the Illness-Cost of Air Pollution (ICAP) in 2005 in Ontario, to be close to 5,800 premature deaths and about $ 1 billion.)
At a price tag of 1 B $ a year for air pollution, the health of the environment and the health of the economy could well be the two sides of the same coin. And human health, the edge of that coin, the interface, the resulting effect?
What if asthma, then, were simply the wheezing, i.e. audible, and breathable part of the quality of life iceberg. And children, smaller, still developing and more vulnerable of the lot, the canary in the coal mine?
November 8, 2006
Causes are not fully understood, so medication is still the focus instead of early prevention.
A close-up of an outdoor poster promoting public transit in Bruxelles, illustrating the link between poor air quality and respiratory problems.
Food one possible cause
Because a child's immune system is not fully developed until the age of five, early breastfeeding is crucial.
The mother's milk contributes to the infant's defenses, explains Leslie Solomonian, Doctor of Naturopathic Medicine and post-graduate resident and faculty member at the Canadian College of Naturopathic Medicine in Toronto.
Solomonian also points to another potential cause: the hygiene hypothesis (see sidebar below).
The later introduction of solid foods should also be carefully planned, adds Solomonian, especially foods more likely to cause allergies, such as wheat, dairy products, soy or eggs.
"Seventy percent of the immune system lies in the gut," explains Dr. Solomonian. "The child's gut lining is not mature and more permeable.” So allergy-causing substances may end up in the blood and challenge a still-growing immune system.
The Canadian National Asthma Control Task Force also agrees. Its
report The Prevention and Management of Asthma in Canada
published in 2000 acknowledges that “breastfeeding and delayed
introduction of solid food may
reduce the incidence of asthma.”
Similarly, Dr. Kerin, an occupational medicine consultant in Toronto, points to the digestive system in childhood development.
“The child's immune system is more immature and may act more aggressively than the more educated, more mature adult system,” he says.
However, the “allergy march” or path to developing allergic reactions may not be entirely straightforward, cautions Dr. Luciuk.
“Breastfeeding decreases the chance of atopy [the genetic predisposition toward the development of immediate hypersensitivity reactions against common environmental antigens], but breastfeeding beyond two years increases infants' susceptibility towards developing allergies related to such strong sensitizers as cow's milk, egg, soybean and peanut.”
The Hygiene Hypothesis
What if being too clean or using too many antibiotics led to the development of allergic reactions, asks the "Hygiene Hypothesis."
The theory could be one of several possible leads into the origin of asthma, acknowledges the head of the Asthma Society of Canada, Frank Viti.
“The wealthier a society becomes," Vity explains, "the more resources there are to sanitize our environment, the more this could in turn contribute to depleting our immune systems.”
Basically, the hygiene hypothesis goes as follows: if a child's sensitive immune system has been overprotected in a bacteria-free environment, his or her immune system may eventually overreact when it encounters unkown foreign substances, once the child gets out of the über-sanitized home cocoon.
Instead, an early exposure of children to many sources of bacteria would educate one's immune system.
“The best place might be a pig farm in Northern Europe,” sais allergy and immunology consultant, Dr. Luciuk.
“This is just an hypothesis,” underlines the B.C. pediatric allergy and clinical immunology specialist.
Indeed, other factors such as smaller families with fewer chances of germ exchange between children, to the excessive or injudicious use of antibiotics, could contribute to the allergy march.
In the end, to reduce the degree of exposure and thus decrease the chances of the immune system over-reacting, the key is early investigation of any potential allergic reaction in an individual, concludes Dr. Luciuk.
Home and Office Hazards
A higher incidence of asthma can be directly linked to occupational and domestic sources, according to Dr. Kerin, a Toronto occupational medicine consultant.
“We had asthma before the last World War, but the rate in the population has increased rapidly, especially in the younger generation,” says Kerin.
“There are more than 200 chemicals in the workplace that can induce, trigger, cause or aggravate asthma," he adds.
More specifically, isocyanides found in plastics and paint, could be at play,
Dr. Kerin also points to domestic sources such as VOCs [volatile organic compounds from cleaning products or furniture such as armchairs or particle-board cabinets], chemical perfumes and air fresheners.]
Health Canada also identifies indoor air pollutants in the home as triggers for respiratory symptoms in asthmatic individuals.
Such domestic substances include formaldehyde, an irritating gas emitted by off-gassing from wood-based materials, such as particle-board, medium-density fibreboard, wood fibres bound together with adhesives under heat and pressure, and plywood, as well as from some paints, varnishes and floor finishes.
Indoor irritants also include nitrogen oxides infiltrating from outdoor sources such as transportation or indoor sources such as gas cooking stoves.
Moulds also form a known source of allergens.
Gender differences are also at play. For instance, boys are more prone than girls to developing asthma (see graph in blue).
However, in adult women, hormonal changes such as puberty or pregnancy could be contributing to the development of allergic reactions, points out Dr. Luciuk. Menopause might have similar consequences.
Photo : Charles-Antoine Rouyer
Original photo of an outdoor poster promoting the STIB public transit system in Bruxelles, on Place Louise. The ad shows the famous Belgian capital bronze statue of a child peeing in a fountain, the "Manneken Pis", but equiped here with a scuba diving oxygen tank and respiratory equipment.
The French tag line reads: "To let Bruxelles breathe, let us chauffeur you". At the bottom, the French reads: "Sortez de la pollution - Entrez dans les voitures de demain" meaning "Get out of pollution - Step into the cars of tomorrow".
Photo : Charles-Antoine Rouyer