27.11.2007

Risks of Multiple Exposures

A case study has shown that the risks incurred with multiple exposures are
still not well understood.

Over the period 2002 ­ 2004 workers constructing an air emissions recovery
boiler in Dryden, Ontario (Canada), were exposed to emissions from other stacks
in the area. These contained chemicals including methanol, sulphur dioxide,
hydrogen sulphide, nitrogen oxide, ammonia and lead manganese.

Despite assurances from the Labour Ministry that there were no health risks
workers reported a range of problems and a later clinic assessment led to
diagnoses of multiple-chemical toxic encephalopathy for many.

The Labour Ministry has committed to monitoring the site and taking corrective
action if air quality becomes a problem.

A case study into numerous illnesses at a Dryden boiler project proves more
work still needs to be done about the perils of multiple exposure, states a
provincial trades official.

"Dryden is an example of a complete failure, a perfect storm,” says Carmine
Tiano, Provincial Building and Construction Trades Council of Ontario WSIB
training and advisory services director.

"It was a complete occupational health and safety system breakdown.”

From 2002 to 2004, more than 300 workers constructed an air emissions recovery
boiler in Dryden. On a regular basis, the workers were exposed to plumes from
adjacent stack emissions blowing into their work area. The emissions contained
chemicals such as methanol, sulphur dioxide, hydrogen sulphide, nitrogen oxide,
ammonia and smaller amounts of lead manganese.

On a number of occasions, Ontario's labour ministry was called in to address
the exposure and it stated there were no health risks. This contradicted the
numerous worker complaints of respiratory, gastrointestinal, cardiac and skin
ailments, says Tiano, who reported the findings of his case study at the recent
provincial trades convention.

"They were told everything was within limits,” notes Tiano. "Three hundred
claims were submitted (under WSIB's Program for Exposure Incident Reporting),
14 were accepted for loss of earning and only one for permanent impairment.”

The Northwestern Ontario Building Trade Council sponsored an intake clinic in
November 2004, which was organized in collaboration with the Sudbury
Occupational Health Clinic of Ontario Workers, to assess the health of workers
on the site.

The 350 workers who attended the clinic answered a medical questionnaire and
were assessed by occupational health physicians.

The diagnosis of the workers was determined to be multiple-chemical toxic
encephalopathy, which indicates a mixture of neurocognitive, neurobehavioural
and autonomic nervous system changes.

"This demonstrated how impoverished intellectually - in understanding
multiple exposure - people can be,” says Tiano.

Though the WSIB did not allocate enough resources to cluster claims, with only
one adjudicator for all 300 Dryden fies, the provincial trades council also
learned some lessons in this case, adds Tiano.

"The building trades were ill prepared to deal with mass exposures and complex
issues as well,” says Tiano. "Although potential health risks were identified
in pre-job work-up, the building trades had little ability to resolve issues
short of work stoppages and walking off the site.”

The Northwestern trades council has developed a health risk protocol since the
Dryden exposure case. Discussions have also been held with labour ministry,
WSIB, employers and the medical community. The protocol is being tested at a
Fort Francis Abitibi Project currently in its initial phases.

"Also what came out of Dryden is that WSIB has consulted with local doctors
about multiple exposure (symptoms and diagnosis),” notes Tiano.

The labour ministry has committed to monitoring the Fort Francis site and
taking corrective action if air quality becomes a problem. The WSIB has
committed to allocate additional resources if cluster claims happen again.

"Over the years we have heard of other cases like this. We have to get our oar
in the water with the government, this type of thing has to stop,” adds
Patrick Dillon, Provincial Building and Construction Trades Council of Ontario
business manager.

More info


AplusA-online.de - Source: National Safety Council of Australia Ltd (NSCA)