A Real and Present Danger

Occupational cancers represent more than half of all work-related disease cases in established market economies, and global estimates of fatal occupational diseases put cancer as the top killer after circulatory disease and work accidents. These are some of the grim statistics on workplace carcinogens that Connie Muncy, senior health and safety administrator with AES Corporation in Dayton, Ohio, shared at Safety 2017 in Denver on June 20.

According to the World Health Organization, new cancer cases are expected to rise by 70 per cent worldwide over the next two decades. “That is staggering,” Muncy says.

Cancer stemming from job exposure to carcinogens is a common threat worldwide. Figures from the International Labour Organization (ILO) in Geneva indicate that 13 per cent of all cancers in developed countries result from preventable, predictable workplace exposure, which translates to 600,000 deaths a year.

Canada faces a similar challenge: occupational cancer has become the leading cause of compensated work-related deaths — a phenomenon that is most notable in Ontario, where job-related cancer fatalities double those for traumatic injury, according to the Occupational Cancer Research Centre and Cancer Care Ontario, both in Toronto.

“Where is the outcry? Where are the campaigns of people trying to stop the tide of occupational cancer?” Muncy questions, stressing that there is a pressing need to elevate the profile of occupational cancer prevention globally.

An elusive killer

Occupational cancer, which is caused wholly or partly by exposure to a cancer-causing agent and a particular set of circumstances at work, is also influenced by factors such as age increase, family history, an individual’s susceptibility to a substance, diet and lifestyle habits, existing medical conditions, the amount and duration of exposure to a carcinogen while on the job and shiftwork.

The National Institute of Occupational Safety and Health (NIOSH) in Washington, D.C. states that three to six per cent of cancers worldwide are caused by workplace exposures to carcinogens, costing $4.3 billion in the United States. “This is probably underestimated,” Muncy notes.

Previous global estimates by the ILO in 2005 established that 32 per cent of work-related deaths in the world are associated with cancer. That statistic is climbing as occupational cancers are rapidly globalized, with the percentage of cancer fatalities among all occupational deaths in industrialized countries approaching that of high-income countries, according to another study, Eliminating Occupational Cancer, published online in July 2015.

“Long-term latent illnesses caused by long-term exposure to carcinogens are difficult to relate to the workplace and are not adequately recognized and reported,” Muncy explains. Although the figures obtained by governments through death certificates, workers’ compensation records and reports to federal and state agencies seek to provide as complete an account of occupational cancer as possible, the United Kingdom Trades Union Congress points out that it is almost impossible to link a specific instance of cancer to a specific exposure to a cancer-causing substance, as many cancers develop decades after the initial exposure.

“Most people who are killed by cancer, it is not visible. They die at home, at the hospital. Out of sight, out of mind,” Muncy says. “So there is an urgent need to harmonize the estimation methods to make them more accurate and complete throughout the world.”

Cancer’s long latency period is part of the reason why this issue does not raise alarm bells for corporate executives who answer to shareholders at annual general meetings. Roughly 100,000 chemicals are used in workplaces around the world, and only one per cent have been thoroughly tested for health risks. “Persistent misconception exists that better regulation is taking care of the problem,” Muncy says. “That is not doing the trick.”

Regarding the slow pace of identifying workplace-cancer risks, “there is good reason to believe that this could be the result of a well-coordinated industry campaign to influence the decisions of bodies, including the IARC and WHO, rather than any actual improvements at work,” she suggests.

As public funding for independent occupational health research is eroded, industry-funded research is swamping the literature, with occupational and environmental risks going underestimated or undetected as a result.

Muncy cites a report, which was published in the October-December 2005 issue of the International Journal of Occupational and Environmental Health, examining business bias in workplace studies. The report concludes that studies of potential occupational and environmental health hazards that are funded directly or indirectly by industry are likely to have negative results.

Complex clusters

The causes of cancer vary, but even more complex is identifying workplace cancer clusters, defined as the occurrence of a greater number of cancer cases than expected among a group of people in a defined geographic area over a specific period. Workplace cancer clusters typically involve the same type of cancer. When several cases of the same type of cancer that is not common in the general population occur, they likely involve occupational exposures.

An investigation of a potential occupational cancer cluster necessitates that only primary cancers — not the spread of a primary cancer into other organs — are used to investigate a cancer cluster and requires the determination of whether the cancer is occurring among employees in particular jobs or areas.

Workplace cancer clusters are a “very real phenomenon,” and determining their occurrences is a “highly complex process,” Muncy says.

Long latency periods of 15 to 20 years aside, the health events being investigated, such as morbidity or mortality rates, are usually rare. Increases in these events tend to be small and occur over a long period of time. Information on the population at risk is often not available — not to mention that some cancer clusters do occur by chance or could result from errors in the calculation of the expected number of cancer cases and differences in how cancer cases were classified, according to the National Institute of Health in Bethesda, Maryland.

Even if a cluster is confirmed, it can be challenging to pinpoint the cause as people move in and out of a geographic area over time, making it difficult for investigators to identify hazards or potential carcinogens to which they may have been exposed and to obtain medical records to confirm the diagnosis of cancer. “Physicians, researchers, epidemiologists, employers, government, unions and individuals all need to get onto the same page,” Muncy says.

Canada has taken a public stand in support of the primary prevention of occupational cancer. In 2005, the NCEOE called on the House of Commons standing committee to back changes in Canadian law to promote preventive measures more effectively. It also called on the Canadian government to strengthen the Canadian Environmental Protection Act in its application, in particular to IARC I- and IIA-designated human carcinogens. The letter also called for bulletins to be developed to address cancer prevention and toxic-use exposure reduction, investigate the possibilities for introducing toxic-use reduction legislation and offer possible incentives for toxic-use reduction programs.

“Right now, it is very, very difficult in the United States to prove an occupational cancer case,” Muncy says, stressing the need to raise awareness to improve risk perception of workplace carcinogens among stakeholders.

Individuals can play a part by spreading the message of workplace carcinogens. “You can empower yourself, your family members and friends on how to protect themselves,” Muncy advises. “Try to do something, even if it is very small.”

Jean Lian is the editor of OHS Canada.