Toronto Star
September 5, 2005


By Mary Cook*

Twenty-five years after the passage of Ontario's Occupational Health
and Safety Act, it would be nice to be able to say on this Labour Day
that, at the very least, we know how many thousands of workers are
stricken each year by diseases related to work.

The bitter truth is, we don't even know that. Part of the reason is
our obsession with scientific proof.

While science has contributed hugely to the quality of our lives, it
has also led to a situation where we now depend on it to provide
answers to every question. The problem, of course, is there are some
issues where science is incapable of providing answers with the
certitude we demand.

Climate change is one example. Scientists can tell us they believe
human activity has an effect on climate but they can't prove it
conclusively. In spite of that scientific caution, Canada and most
other countries have decided to act because the consequences of not
acting are so great.

In the case of greenhouse gas emissions, society has decided to apply
the precautionary principle, which says we're better safe than sorry.

But there's a similar example where science and public policy collide.
It's a case that, for many people, has a much more immediate effect on
their lives but we have yet to take the same cautionary step.

It's the silent epidemic of occupational disease.

The World Health Organization estimates that 1,000 new chemicals are
introduced into workplaces every year. Given the array of workplace
chemicals in use, it's no surprise that cancer is an occupational

Again, precise numbers are hard to come by. Cancer Care Ontario
suggests about 4 per cent of cancers may be related to occupational

Even at that conservative estimate, there would be about 2,000 new
occupational cancer cases in Ontario each year. But in 2003, only 51
lost-time cancer claims were allowed, according to the Annual Report
of the Workplace Safety and Insurance Board.

There are several reasons for the lack of precise numbers about the
extent of the problem. There is no database of occupational disease in
Ontario -- no one keeps records. In addition, Ontario doctors are not
required to report incidences of occupational disease. Sexually
transmitted diseases, yes; gunshot wounds, yes; mesothelioma from
asbestos exposure, no.

As well, medical schools do a poor job of educating doctors about
occupational disease.

Staff at Ontario's five occupational health clinics have seen cases
where family or company physicians have declared patients to be in
good health even though they have diseases like asbestosis.

Legislation can deal with some of those issues. But the bigger problem
is our insistence on amassing unequivocal scientific proof before we
even acknowledge that there is a problem.

The particular science involved in ferreting out medical mysteries is
epidemiology, the study of disease patterns among populations.

But epidemiology may simply be too crude a tool to investigate the
clusters of occupational diseases that occur, for the simple reason
that the number of cases is usually too small.

Scientists are trained to look for high levels of statistical
significance and avoid false positives -- finding associations where
none exist.

This deep-seated avoidance however leads to another problem: making
false negatives -- the failure to identify an association where one
really does exist.

When studying occupational disease, it is often not possible to
collect data of adequate quality and quantity to achieve statistical
significance. That puts workers' health in jeopardy.

Science and numbers go together and scientists have strict protocols
on what kind of evidence they consider.

That leaves workers unable to depend on more qualitative forms of
evidence that can show links between disease and work.

Qualitative data include employment and exposure history, the
occurrence of symptoms or diseases within a workforce, or even
testimony by co-workers.

In the context of workers' compensation, the burden of proof should
not be on exposed workers to prove work has made them sick.

"Better safe than sorry" was a principle good enough for our
grandmothers. When dealing with the silent epidemic of occupational
disease, it should be good enough for us.

Governments, industry and the WSIB, should follow the same
precautionary principle.

* Mary Cook is the managing director of the Occupational Health Clinics
for Ontario Workers (OHCOW).

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