OHS Canada Magazine

Deadly Mimicry

February 27, 2013

Occupational Hygiene Occupational diseases/infectious diseases

The women working in the heart of the automotive district in southern Ontario are unlike any other autoworkers in the world.

The women working in the heart of the automotive district in southern Ontario are unlike any other autoworkers in the world.

Their plants in Windsor, which manufacture the majority of cars in the country, hire an exceptionally high number of women. Although the workforce is largely represented by the fairer sex, health concerns unique to these autoworkers have previously flown under the radar.

In November of 2012, a groundbreaking study linked a heightened risk of breast cancer with the automotive plastics industry, shedding light on what many of these women say they only discussed in hushed tones and behind closed doors — until now.


The six-year study, spanning from 2002 through 2008, looked at 1,006 women with breast cancer and 1,146 women without the disease in Essex and Kent counties in southern Ontario, where there is an extensive base of manufacturing and agriculture industries. Jobs classified as highly exposed to cancer-causing substances and endocrine-disrupting chemicals include automotive plastics, agriculture, food canning, metalworking, bars and the gambling industry.


Findings reveal a statistically significant association between breast cancer risk and work in high-risk jobs. Women employed for 10 years in these occupational groups were found to have approximately 42 per cent higher risk of developing breast cancer — the most common form of cancer diagnosed in women, the study notes. 

“Why do essentially healthy women develop this disease? It is really important to look at the most highly exposed population, because they usually are the ones that can indicate potential associations,” says James Brophy, one of two lead authors of the study and an adjunct professor at the University of Windsor.

While previous research has hinted a connection between these chemicals and certain types of cancer, this study claims to be the first to link breast cancer risk with occupational hazards.

And the findings are disconcerting: breast cancer risk increased more than two-fold among women employed in the automotive plastics and food canning industries. That number rose almost five-fold for those who were pre-menopausal. Female workers in the farming sector have a 36 per cent higher risk of breast cancer, with several pesticides being fingered as mammary carcinogens.

Those in metalworking were found to have a whopping 73 per cent heightened risk as a result of exposure to a variety of potentially hazardous metals and chemicals used in tooling, foundries and metal parts manufacturing. Women who hold jobs in bars, casinos or racetracks demonstrate a two-fold risk of breast cancer. This is likely due in part to second hand smoke and night-shift work, which has previously been found to affect the endocrine system.

As cancer develops in different stages, the timing of exposure plays a key role in the growth of hormones in a woman’s breast tissue. In general, a woman is increasingly more vulnerable to hormone-mimicking agents the younger she is, the study adds.

According to information from the Breast Cancer Fund in San Francisco, phthalates are a group of endocrine-disrupting chemicals used to render plastics soft and flexible. It can be absorbed by the body through the skin, ingestion, inhalation or medical injection procedures and is found in polyvinyl chloride — commonly known as PVC — which is used to make a wide range of products. They include toys, cosmetics, pharmaceuticals, baby bottles, building materials and automobiles.


Sandy Knight, who has worked in the automotive plastics industry for 20 years, personifies the cold statistics. In 2001, Knight, who was the health and safety representative at her factory in Windsor, was diagnosed with breast cancer and had to undergo a mastectomy to have her lymph nodes removed.

“When I was diagnosed, it was a disbelief,” Knight recalls. “In the back of my mind, I always thought it might have something to do with the plastics,” Knight says.

She began to see the light after reading up on carcinogenic chemicals and the effect they have on the body. “I may not believe it 100 per cent caused the cancer, but I believe it contributed.”

In the study, most plastics manufacturing jobs held by women involved injection moulding. The process requires handling molten mixtures, such as resins and monomers, and forming them into defined shapes. The resulting vapour or mist released into the air can put anyone in the area at an elevated risk of inhalation and exposure — a hazard that is amplified by physical contact.

Emissions are created when pigments, dyes, flame-retardants, plasticizers and ultraviolet protectors are used during the processing of plastic. Overheating of plastic materials is another common root of polymer fumes, smoke and gases. By processing such materials, resins are forced through plastic presses at extremely hot temperatures, Brophy explains in a forthcoming publication.

“Our occupational standards are completely inadequate. Most of them haven’t been altered for 40 years and not a single one of them accounts for the ability of a synthetic chemical to mimic hormones,” Brophy contends. He cites the “complete breakdown in engineering controls” observed in some plants in Windsor. “We couldn’t find, with one exception, any of the plastics plants that had any local ventilation on these machines, even though these women are being exposed on a daily basis to what they refer to — and which we agree — [as] a toxic soup.”

It is on the floor of automotive plastics plants where workers find themselves exposed to this toxic soup of chemicals, comprising solvents, phthalates, styrene and bisphenol A (BPA), which was banned in 2010 in Canada for the manufacturing of baby bottles.

In particular, three types of plastics have been found to leach toxic chemicals when heated, worn out or put under pressure: polycarbonate (which leaches BPA); polystyrene (which leaches styrene); and PVC (which leaches phthalates), notes information from the Breast Cancer Fund.

Vinyl chloride, which is formed in the making of PVC and one of the first chemicals to be designated as a known human carcinogen by the International Agency for Research on Cancer in Lyon, France, has also been previously linked to an increased mortality rate from breast cancer among those who manufacture the material. 

On a day-to-day basis, poor ventilation and clean-up processes are likely suspects in the health repercussions reported by workers. Women who participated in the study recalled excess globs of steaming, smelly plastic oozing on to the floor and complained about poor ventilation systems. Knight says she remembers seeing her fellow female co-workers and friends suffer from nosebleeds, headaches, dizziness — even extreme instances of miscarriages and leukemia.

But female employees, especially those in the automotive sector in Windsor, remain tight-lipped, fearing for their jobs or reprisals from their bosses if they raise their concerns.

Gina DeSantis, who works in an automotive plant in Windsor, says most women residing in the area make a living in these plants. Like her mother, she got a job at the automotive factory, with DeSantis’ daughter following in their footsteps. Three generations of watching fellow female co-workers becoming ill did not stop DeSantis from going to work each day — it is simply a
way of life. 

“Workers are nervous about this,” suggests Jeanne Rizzo, president of the Breast Cancer Fund. “They don’t want to be in a situation that if they complain too much and if it is too costly to meet the health demands, then they will move the plants. So they are a lower income group of people that are, really, pretty much stuck.”


In order to protect workers, legislative regulations dictate the appropriate Threshold Limit Value (TLV) that each workplace must adhere to. Bob Whiting, senior project manager at the Canadian Centre for Occupational Health and Safety in Hamilton, Ontario, points out that these harmful substances are not toxic in the conventional sense.

“Normally when you have a TLV, you are looking for a prevention, for finding out what levels cause health effects and then making sure you are way below that,” Whiting explains, noting that TLVs are established when there is a proven or observable acute health effect. “But if you are not aware of the health affects, then what levels do you control?”

Further complicating the matter is the fact that the evidence presented in the Windsor study covers relatively new territory: only three prior related studies have probed the connection between breast cancer risk and exposure to endocrine-disruptors — one of which examined the relationship between hormone-mimicking chemicals and animals.

“You rarely hear of women workers being studied and whether there is a gender bias out there or not, occupational exposure studies on women are few and far between,” argues Sari Sairanen, the health, safety and environment director of the Canadian Auto Workers union in Toronto.


While more definitive research is needed to bolster our understanding of occupational exposure risks on the incidence of breast cancer, studies conducted in recent years may shed some light.

A study, Exposure to Phthalates and Breast Cancer Risk in Northern Mexico, released in 2010, indicates that exposure to phthalates can lead to an increased risk of breast cancer in women. The study assessed the urinary concentrations of nine phthalate metabolites and breast cancer incidence among 233 women with breast cancer and 221 healthy women in northern Mexico.

After adjusting for breast cancer risk factors, results indicate that phthalate metabolites were detected in at least 82 per cent of women. The geometric mean concentrations of monoethyl phthalate were found to be higher in study subjects with breast cancer than those in the control group. This led to the conclusion that monoethyl phthalate urinary concentrations were positively associated with breast cancer — an association that became stronger for pre-menopausal women.

Another study out of France in 2011 linked occupational exposures to chemicals, solvents and non-metallic mineral products to a high risk of breast cancer. Findings were based on data derived from 1,230 breast cancer cases and 1,315 population controls with detailed information on lifetime work history.

Women employed in the manufacture of chemicals and non-metallic mineral products have a higher incidence of breast cancer, while the risk was decreased among women in agriculture. Results suggest a possible role of occupational exposures in breast cancer, including night-shift work, solvents and endocrine-disrupting chemicals.

Although exposure levels are standardized and regulated in safety codes, the problem is compounded when these substances are combined. “What makes it very difficult is the synergies of chemicals that workers are exposed to. We have exposure limits on single chemicals, but not when they are in unison,” Sairanen contends. “How do you control your exposure to these hazards when the Threshold Limit Value tells you that you are within the norms, but then you have five other chemicals that you are exposed to?”

Exposure to combinations of chemicals can occur partly because many workers have multiple job responsibilities. Drilling, grinding, sanding and buffing can produce dust, while painting or gluing products can take place in a spray booth with poor ventilation. 

As breast cancer can take years — sometimes decades — to develop, the study suggests that health and safety standards (or lack thereof) in factories during the 1970s or 1980s may be a contributing factor to female employees who are now showing symptoms of, or are being diagnosed with breast cancer.

Take as an example the Pontiac Fiero, a sports car made almost entirely out of plastic in the mid- to late- ’80s. “That was a plastic vehicle. The compound, the glues that were used were cancer-inducing and no matter what we did, we could not get enough air quality in a plant to prevent this concentration of those chemicals,” says Steve Rodgers, president of the Toronto-based Automotive Parts Manufacturers’ Association, which represents 90 per cent of independent parts producers in the country. “And consequently, plastic body vehicles died.”

While Rodgers acknowledges that the Windsor study, which establishes a correlation between plastics and endocrine-disruptors, has some clout, the majority of employers have indicated that researchers need to take a closer look at the problem before any definitive conclusions can be drawn.

Kathryn St. John, senior director of communications at the American Chemistry Council in Washington, D.C., points out that the study only examines occupations, rather than exposure levels, to substances themselves. She cites a slew of outlying factors — family history, lifestyle and age — that must be considered before raising alarm bells.

“The potential carcinogenic properties of chemicals and the ability of some agents to affect the endocrine system are all subjects of intense research and testing. Most evidence is mixed and does not indicate any clear breast cancer-causing agents that would operate in humans at exposure levels that they experience in the environment or workplace,” St. John says in a statement.

However, Rizzo counters that the study authors did take those factors into account. By enlisting almost the same number of women — both with and without breast cancer — and tracking the details of their personal and work lives, study authors were able to control for such variables.

“The thing that was consistent was the work history in automotive plastics,” Rizzo notes. 


Perhaps the most vital change to mitigate the dangers associated with exposure to potentially harmful atmospheres is ventilation.

Rodgers says changing out the air in the facility is vital to maintaining clean air inside the factory, which in turn alters the volume of air in the plant. He estimates that many facilities go through this process 10 or 12 times every hour, on the hour.

As well, equipment must comply with the latest safety measures. Rodgers cites the newer models of shot sleeves, used in the injection moulding process to exert pressure on molten plastic in a cylindrical tube to form the material, are made with better controls and more effective seals. This ensures that the plastic is melted within a confined, controlled space and keep workers from being exposed to excess muck
spurting out when opening the mould.

There is also a difference between the plastic manufactured today from those a generation ago. The make-up of plastics contributes to potentially hazardous fumes eking out of exhaust pipes. What goes in, comes out much worse.

“If you have high sulphur fuel going in, you are going to have to have more contaminants coming out,” Rodgers says. If more attention is paid to the purity of resins, that will contribute to a cleaner atmosphere. Personal protective equipment is usually the last line of defense as they tend to be uncomfortable for machine operators, he adds.

Nadia Collins, who works as the workers’ compensation representative for her local union and financial secretary with the Ford Motor Company plant in Oakville, Ontario, says protective gear for women was a luxury back when she started working for an automotive company 29 years ago.

“Simple equipment, such as gloves for women, was a novelty. We had to take the gloves home, wash them, shrink them in the dryer to fit our bodies,” Collins recounts, adding that safety measures have since improved by leaps and bounds. 

For instance, the past practice of dumping excess molten plastic from injection moulding machines onto the floor where it might lay for up to an hour, is now safely transferred into covered barrels.

Just as safety codes have only come up to par in recent decades, it could take some time for workers’ compensation boards to catch up with advances in knowledge. Collins says the recent study opens up the possibility of compensation, although establishing breast cancer as an occupational illness can prove challenging, given its long latency.

“The legislation says that in order to be entitled to benefits for a work-related injury, it must be shown that it [happened] in the course of employment, not at the course of employment,” Collins notes.

Most workers’ compensation boards in Canada — with the exception of Manitoba — have yet to recognize breast cancer as an occupational disease. In 2011, the prairie province included breast, prostate and skin cancer into the list of presumptive cancers, although it applies only to firefighters employed by the Office of the Fire Commissioner.

For industry stakeholders and employees, the study is only the first step towards understanding the link between the most common form of cancer in females and their workplaces. But for women like Knight, who have spent decades working in automotive plastics plants and are just beginning to deal with the health effects fo what is believed to be caused by occupational exposure, the study raises questions that might not even have been asked.

“To me, there has got to be a link,” Knight opines. “Everybody has got to get involved and stop using us as a canary in the mine. I went to work healthy at 19; I should have left there healthy.”

Sabrina Nanji is editorial assistant of Canadian Occupational Health and Safety News.



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