Cleaning products and breast cancer

From

Summary

A study published (July 19, 2010) in the journal Environmental Health claimed to link cleaning, air freshening and mold/mildew control products with increased risk of breast cancer.

According to the press release accompanying the study:

Julia Brody, from the Silent Spring Institute, USA, worked with a team of researchers to carry out telephone interviews with 787 women diagnosed with breast cancer and 721 comparison women. She said, "Women who reported the highest combined cleaning product use had a doubled risk of breast cancer compared to those with the lowest reported use. Use of air fresheners and products for mold and mildew control were associated with increased risk. To our knowledge, this is the first published report on cleaning product use and risk of breast cancer."

What you need to know about this study:

• Dubious correlations. The reported statistical associations are weak and inherently suspect. Moreover, the reported increases in “risk” do not appear to be statistically significant. No p-values were reported for the relative risks so it may be assumed that they exceeded p=0.05.
• Dubious data. The study relies on self-reported data for use of cleaning products and health information.
  • Self-reported data are inherently unreliable.
  • Exposure of study subjects to any chemicals of potential concern is uncertain since use does not equal exposure.
• Faulty trend analysis. In lieu of statistically significant RRs, the researchers try to show a statistically significant increase in RRs with increasing exposure. However, the RRs used in the trend analysis mostly aren’t statistically significant and so can’t serve as true points in a trend.
• No biological plausibility. Exposure to cleaning products is not a known cause or contributor to cancer in animals or humans.
• Sponsor bias. The study was sponsored by the Silent Spring Institute, an activist organization based on the legacy of Rachel Carson, Silent Spring and the assumption that chemicals in the environment cause cancer.

This study does not link cleaning product use with breast cancer.

Additional Resources

• ACI Refutes Study Attacking Cleaning Product Safety, Links to Breast Cancer, American Cleaning Institute, July 20, 2010.