A breast cancer survivor who was exposed to a toxic mix of cancer-causing chemicals on the job at a plastic factory 20 years ago is warning that the health of workers still isn't protected enough. 

Sandy Knight, a former health and safety chairperson at a plastics factory in Windsor, Ont., now speaks to men and women about potentially dangerous substances in the workplace. 

She says she hears about five-minute brush-up sessions on the dangers, which Knight calls little help when an industry has high worker turnover rates.

"I was just so amazed to hear what's going on," the Burlington, Ont., resident  said. "You're doing what we did back in the '80s," such as working without adequate ventilation.

Provincial and federal laws regulate the use of known cancer-causing substances in the workplace, but some experts say workplace exposure to carcinogens has not come under enough scrutiny. 

As part of a three-part series, Exposed: On the Job, CBC News looked at what carcinogens are present in Canadian workplaces and how Canadian regulations stand up.

Workers 'hardly protected'

Researchers Jim Brophy and Margaret Keith are trying to determine how breast cancer may be caused by exposure to carcinogens in the workplace, part of their ongoing effort to raise concern about on-the-job exposures to toxic substances.

"Blue-collar industrial workers are hardly being protected by current standards that almost no one is enforcing," said Brophy.

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Breast cancer survivor Sandy Knight wants workers to press for more safety measures in factories. (Courtesy of Brandon Knight)

Brophy and Keith, who have worked in occupational and environmental health for 30 years in the Windsor, Ont., area, have combined provincial labour inspectors' reports with the observations of female workers employed in the plastics industry dating back to the 1960s.

By piecing together the historical exposures, the researchers, who are working under a Health Canada grant given to York University's National Network on the Environment and Women's Health, hope to learn more about why more breast cancers are occurring now in industrialized countries.

Asbestos was the first carcinogen to raise concerns with the two researchers — and they believe the impact of the hazardous fibre's use is far from over.  

"We're seeing just the tip of the iceberg for asbestos disease," said Brophy, since few cases are recognized by family doctors.

Applying the most conservative U.S. estimate north of the border, they believe 3,345 cancers in Ontario might be work-related every year. If each patient's health-care cost ran up to $100,000, that totals a $334-million cost to taxpayers instead of workplace compensation.

Too 'full' of tumours

When Knight was diagnosed with Stage 3 breast cancer in 2000, the ultrasound was never completed. Knight was told she was so "full" of tumours that surgeons had to move quickly to fight the fast-growing, spreadable cancer.

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The timing of exposure to carcinogens is important in breast cancer, Jim Brophy and Margaret Keith say. (Courtesy of Jim Brophy)

After Knight noticed a lump, she insisted on a second opinion because of an unusual black mark.

Her doctor had relied on her lack of a family history for cancer, age, asked about the cigarettes she smoked on and off, drinking and stress levels. But Knight wasn't asked about the carcinogens she was exposed to at work.

"I almost slipped through the cracks," Knight, now 53, recalled.

Starting in 1978, Knight worked mostly in the paint shop at the Windsor plant. Back then, masks weren't mandatory and workers didn't wear them as they applied paint thinners. They likely breathed in hot, smelly vapours from chemicals that are now known to cause cancer in humans, such as benzene, vinyl chloride and formaldehyde.

Brophy and Keith's focus group participants recalled a process called purging. Plastics were burned out of machines and left to smoulder in common areas on the shop floor. The formaldehyde fumes were "concerning" during purging at high temperatures, government inspectors said.

Since cancer takes so long to develop, damaging health effects from those exposures could only be surfacing now, researchers say.

The materials used to make plastics have changed over the years, making it harder for scientists to identify which workplace exposures might increase the risk of cancer. Researchers also say findings in male workers may not translate to female workers with different body sizes, hormones and sensitive reproductive organs.

The $20.7 billion per year plastics industry employs about 91,000 people, mainly in small and medium-sized firms, according to Industry Canada and Statistics Canada.

Causes of breast cancer

No firm scientific consensus has been established between workers' exposure in the plastics industry and higher breast cancer risk, according to the authoritative International Agency for Cancer Research (IARC).

Knight says she realizes there isn't 100 per cent proof that the plastics industry contributed to her cancer and she doesn't blame the company since she was also a smoker — another deadly source of many of the same carcinogens.

However, she does advise Canadians to take precautions in the workplace, including:

  • Get informed.
  • Protect yourself.
  • Don't accept that companies will close shop and move when forced to add preventive measures like local ventilation or robots for hazardous tasks.
  • Trust your instincts about getting a second opinion or test. 

Cancer detective work

Since the 1970s, the U.S. government has estimated that four to eight per cent of cancers are related to how we earn a paycheque.

But no one really knows how many cancers are work-related. Part of the problem is doctors often don't ask for workplace information. Employees also don't take note of their carcinogen exposure or accurately remember past ones.

"Most physicians are not aware of what kind of work-related exposures their patients have," said Paul Demers, CAREX Canada's scientific director in Toronto.

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Paul Demers wants doctors to be aware of their patients' exposure to carcinogens at work. (Evan Mitsui/CBC)

By being aware of those exposures, doctors can be on the alert for related health effects later on, Demers said.

Demers is part of a University of British Columbia group trying to pinpoint how many Canadians are exposed to carcinogens in an effort to raise awareness and help prevent workplace cancers.

CAREX Canada's researchers are building a large database of exposures to different carcinogens using records from federal and provincial agencies, then analyzing the data to estimate the number of workers exposed. 

Canada has done sophisticated work on prioritizing substances of concern, such as those under the federal chemicals management plan, said Joel Tickner, a professor in the School of Health & Environment at the University of Massachusetts Lowell.

"The challenge is how do we use that ... to stimulate the transition to safer chemistry?"

This article is the second in a three-part series about cancer-causing agents in the workplace.