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Exposure to toxic soup of chemicals at work increases breast cancer risk

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Women who work in jobs where they are exposed to a ‘toxic soup’ of chemicals are at a much higher risk of developing breast cancer, according to an international research study lead by the University of Stirling’s Occupational and Environmental Health Research Group (OEHRG).

The case control study, involving 1006 women with breast cancer and 1146 without the disease, revealed that women who worked for 10 years in jobs classified as highly exposed increased their breast cancer risk by 42 per cent.

Lead researchers for the study, Dr James Brophy and Dr Margaret Keith, work for OEHRG as well as the University of Windsor in Ontario. Dr Brophy said: “Breast cancer causality is complex. It is believed to result from a combination of factors including genetic, hormonal and lifestyle influences as well as environmental exposures.

“However, studies have shown that breast cancer incidence rose throughout the developed world during in the second half of the twentieth century as women entered industrial workplaces and many new and untested chemicals were being introduced. Diverse and concentrated exposures to carcinogens and hormone disrupting chemicals in some workplaces can put workers at an increased risk for developing cancer.”

The study, which also involved researchers from Canada, USA and the UK, contributes to a better understanding of cancer causation, particularly for work related cancer. While the research was conducted in Southern Ontario, Canada where there is extensive manufacturing and agriculture, its findings have relevance to women working in a variety of industries across the globe.

Professor Andrew Watterson, Head of the OEHRG at Stirling and a co-investigator on the project said: “Many workers face multiple exposures to chemicals, not only from their employment, but from their everyday environment. Many of the women included in the study were exposed to a virtual ‘toxic soup’ of chemicals. Untangling work and wider factors in the possible causes of breast cancer is an important global issue.”

The study found several occupational sectors in which there was elevated breast cancer risk:

Farming: showed a 36 per cent increased breast cancer risk. Several pesticides act as mammary carcinogens and many are endocrine disrupting chemicals. Employment in farming and exposure to pesticides in Canada often begins earlier in women’s lives than other occupations and may play a role. The chemicals may be the same in the UK but exposures may occur at a later date.

Plastics: The risk of developing breast cancer doubles for women working in the Canadian car industry’s plastics manufacturing sector. Among those who were premenopausal, the risk was almost five times as great. Many plastics have been found to release estrogenic and carcinogenic chemicals and cumulative exposures to mixtures of these chemicals are a significant concern. Many of the plastics chemicals used in Canada are identical to ones used all over the world, including the UK, in a variety of manufacturing sectors. The UK is proposing weakening inspections in this sector.

Food Tinning: The risk of developing breast cancer doubles for women working in the tinned food sector. Among those who were premenopausal, the risk was five times as great. Exposures to chemicals in the food canning industry may include pesticide residues and emissions from the polymer linings of tins. There has been little research conducted on women’s health in this industry anywhere in the world.

Metalworking: A statistically significant 73 per cent increased breast cancer risk was found in the metalworking sector. Women working in tooling, foundries and metal parts manufacturing are exposed to a variety of potentially hazardous metals and chemicals. There has been little research conducted on breast cancer risk in this area, but this could have relevance for a broad range of unskilled, semi-skilled and skilled workers in various industrial operations.

Bar/Casino/Racecourses: The risk of developing breast cancer doubles for women working in the bar/casino/racing sector. The elevated risk of developing breast cancer may be linked to second-hand smoke exposure and night work which has been found to disrupt the endocrine system.

Dr Brophy called for further research to be funded as a matter of urgency: “The study of occupational risks for breast cancer is a neglected area of research. This study points to the value of including detailed work histories in the environmental and occupational epidemiology of breast cancer. Resources should be aggressively allocated to preventing occupational exposures to cancer-causing and endocrine disrupting chemicals linked to breast cancer in Canada and the UK.”

The study could also have wider implications for society as a whole. Dr Keith added: “The findings from this occupational study have important implications for the general public. We may be exposed to many of these same cancer-causing and endocrine-disrupting chemicals on a daily basis, albeit likely at much lower levels. The study also points to the need to re-evaluate occupational and environmental exposure standards, keeping in mind that there may be no determinable safe levels to cancer-causing or hormone-disrupting chemicals.”

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