Chrysotile in Thetford: A Danger to Public Health?
Alarmist Article in La Presse Doesn’t Tell the Whole Story
André Noël’s article ‘Thetford’s Air Polluted by Asbestos’ (‘L’air de Thetford
pollué par l’amiante’ in La Presse, November 7, 2007) is based on a report
published in the International Journal of Occupational and Environmental Health.
It does not, however, appear that the writer either consulted relevantly informed
scientists or familiarized himself with other literature on the subject, including
recent scientific studies.
Instead, it seems Mr. Noël could not resist the temptation to indulge in journalistic
scaremongering. A careful examination of the report on which his article is
based shows that, according to results of the NIOSH 7402 testing carried out in
several Thetford houses between August and November of 2003, there was
never more than 0.001 f/cc of asbestos present in the air. Only between July and
August was the concentration slightly higher, peaking once at 0.006 f/cc.
Even this concentration of fibre in the air is 1000 times lower than the acceptable
maximum in work environments (1 f/cc) and ten times lower than the level of
concentration deemed unacceptable for buildings in Quebec (0.01 f/cc), a level
France’s National Institute of Health and Medical Research (INSERM) does not
consider to pose any excess risk of cancer.
At such low levels of concentration, there is little credible, scientific evidence to
support any claim that the population is measurably and unacceptably at risk. A
study of the effects of airborne fibres on residents of chrysotile asbestos mining
towns, where their concentration was anywhere between 200 to 500 times higher
than in other North American towns and cities, showed that residents of the
mining towns were no more affected by asbestos-related illness than residents of
other towns, despite their exposure to higher concentrations of airborne fibres.i
More recently, a risk assessment conducted by France’s National Academy of
Medicine (ANM) concluded, “…as it affects the general population, an average
concentration of 1 fibre per litre of air (0.001 f/cc) is perfectly safe.”[Our
translation] In work environments, the ANM determined that “…exposure to 100
fibres per litre of air (0.1 f/ml) eight hours a day, five days a week, over a period
of ten years, is not considered appreciably dangerous as far as lung cancer is
concerned, and likewise presents no measurable danger related to
mesothelioma.” [Our translation] (From a report by an ANM task force adopted
unanimously on April 30, 1996)
It should be noted that asbestos fibres have always occurred naturally in the air,
even before industrial mining began. Their presence is caused by the natural
erosion of geological formations found throughout the world, and which are a
natural source of airborne fibres often at levels of concentration far greater than
those produced as the result of mining activities. Rarely do naturally occurring
levels of concentration exceed a usual 0.001 f/cc. If these concentrations pose
any health risk at all, that risk is undetectable and less significant than any health
risks associated with naturally occurring radiation. As such, the World Health
Organization has determined the risk of such levels of airborne chrysotile fibres
to be ‘acceptable’, while the Ontario Royal Commission on Asbestos (ORCA)
calls it ‘not significant’, and the United Kingdom’s Royal Society has stated that
no allocation of resources to managing the risk would be justifiable.
As early as 1984, ORCA pointed out that, “The risk that an individual who had
been exposed to asbestos in a building to, say, 10 years would die of an
asbestos-related disease is less than 1/50 the risk that death would come from
commuting 10 miles by automobile to and from that building daily for the same
period. At this level, we deem the risk which asbestos poses to building
occupants to be insignificant and therefore find that asbestos in building air will
almost never pose a health hazard to building occupants.”
In a recent study of women unexposed to asbestos in a work environment in
Quebec’s Thetford and Asbestos mining regions, the incidence of death from
lung cancer was compared to that among women in 60 other regions (Camus,
M., Siemiatycki, J., & Meek, B. New England Journal of Medicine 338 (1998):
1565-1571). The study’s authors stated, “We found no measurable excess risk
of death due to lung cancer among women in two chrysotile-asbestos-mining
regions. The EPA's model overestimated the risk of asbestos-induced lung
cancer by at least a factor of 10.”
We hope this will serve to eliminate any misapprehension resulting from André
Noël’s article and trust that in the future, thorough research will be conducted and
experts consulted when dealing with complicated subjects and before
unjustifiably alarmist articles are published.
The Chrysotile Institute is an independent organization established in 1984 by the
governments of Canada and Quebec, unions and industry representatives. Its mission is
to promote the safe and responsible use of chrysotile in Canada and the world.
The study’s author, a recognized pathologist at the University of British Columbia’s Faculty of Medicine,
drew the following conclusion: “These observations should provide reassurance that exposure to chrysotile
asbestos from urban air in public buildings will not produce detectable disease.” (Churg, A. ‘Lung Asbestos
Content in Long-term Residents of a Chrysotile Mining Town.’ American Review of Respiratory Disease.
134 (1) (1998): 125-127
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