Study Suggests Link Between Cleaning Products and Breast Cancer

July 20, 2010

A new study suggests that using household cleaning and pesticide products could contribute to an increased risk of women developing breast cancer, as many of these products contain endocrine-disrupting chemicals or mammary gland carcinogens.

In the paper published today in the journal Environmental Health ("Self-reported chemicals exposure, beliefs about disease causation, and risk of breast cancer in the Cape Cod breast cancer and environment study: a case-control study") researchers Ami R. Zota , Ann Aschengrau , Ruthann A. Rudel and Julia Green Brody reported that they interviewed by telephone 787 women living in Cape Cod, Mass. who have been diagnosed with breast cancer between 1988 and 1995, as well as 721 controls. Telephone interviews asked about product use, beliefs about breast cancer etiology, and established and suspected breast cancer risk factors. To evaluate potential recall bias, the researchers said they stratified product-use odds ratios by beliefs about whether chemicals and pollutants contribute to breast cancer; they compared these results with odds ratios for family history (which are less subject to recall bias) stratified by beliefs about heredity.

The researchers found that breast cancer risk increased two-fold in the highest compared with lowest quartile of self-reported combined cleaning product use (Adjusted OR = 2.1, 95% CI: 1.4, 3.3) and combined air freshener use (Adjusted OR = 1.9, 95% CI: 1.2, 3.0). Little association was observed with pesticide use. According to the researchers, in stratified analyses, cleaning products odds ratios were more elevated among participants who believed pollutants contribute "a lot" to breast cancer and moved towards the null among the other participants. In comparison, the odds ratio for breast cancer and family history was markedly higher among women who believed that heredity contributes "a lot" (OR = 2.6, 95% CI: 1.9, 3.6) and not elevated among others (OR = 0.7, 95% CI: 0.5, 1.1).

Zota and colleagues say the results of this study "suggest that cleaning product use contributes to increased breast cancer risk. However, results also highlight the difficulty of distinguishing in retrospective self-report studies between valid associations and the influence of recall bias. Recall bias may influence higher odds ratios for product use among participants who believed that chemicals and pollutants contribute to breast cancer. Alternatively, the influence of experience on beliefs is another explanation, illustrated by the protective odds ratio for family history among women who do not believe heredity contributes 'a lot.' Because exposure to chemicals from household cleaning products is a biologically plausible cause of breast cancer and avoidable, associations reported here should be further examined prospectively."

The American Cleaning Institute (ACI) says it is challenging the study's results. "Simply put, this research is rife with innuendo and speculation about the safety of cleaning products and their ingredients," says Richard Sedlak, ACIs senior vice president of technical and international affairs. "This is all based on the most cursory look at the scientific literature and the recollection of breast cancer survivors as to the products they used 15 to 20 years ago. Although the authors recognize the potential bias in their results, present conflicting findings, and have no real gauge as to the products used by the interviewees so long ago, they proceed to make unscientific assumptions on a very shaky foundation. Unfortunately, this work sheds little light on the real causes of breast cancer." Sedlak adds, "The safe and responsible manufacture and use of cleaning products is an absolute top priority within our industry. Further, the plausibility of avoiding cleaning products, as put forth by the researchers, in a world where hygiene and cleanliness are the first barriers to disease prevention, is theoretically plausible, but the adverse effect on public health would be real."

Reference: Zota AR, et al. Self-reported chemicals exposure, beliefs about disease causation, and risk of breast cancer in the Cape Cod Breast Cancer and Environment Study: a case-control study. Environmental Health 2010, 9:40doi:10.1186/1476-069X-9-40