Polycyclic aromatic hydrocarbons (PAHs) are compounds formed during the incomplete burning of coal, oil and gas, garbage, food and other organic substances. PAHs are found primarily in smoked foods, well-done meat and fish, cooking oil fumes, cigarette smoke, and vehicle exhaust. Exposure to PAHs is a known breast cancer risk factor, especially for hormone receptor positive (ER+/PR+) disease. Now a new study has reported that exposure to multiple sources of PAHs can result in significantly increased breast cancer risk.

Sources of PAH exposure

The following sources of PAH exposure have found specifically to be linked to increased breast cancer risk:

  • Motor vehicle exhaust (living or working near high-traffic roadways)
  • Smoke generated by grilling and barbecuing
  • Smoke from burning synthetic fireplace logs
  • Tobacco smoke, including second-hand smoke
  • Smoke-cured fish and meats, especially wood-smoked
  • Well-done meat or fish, especially when cooked over open flame.
Generally speaking, foods made with smoke flavorings have a lower level of PAHs than foods that have actually been smoked.

Latest research finds multiple sources of PAHs can increase risk

The case-control study referenced at the beginning of this news story was designed to investigate the influence of multiple sources of exposure to PAHs on breast cancer risk. While exposures to various single sources of PAHs have been found to be associated with increased breast cancer risk, most women are exposed to multiple sources. The present study examined the risk of breast cancer from multiple PAH sources in a single model in an attempt to more accurately reflect exposure to complex PAH mixtures. The study included 1,508 breast cancer cases and 1,556 cancer-free controls in Long Island, New York. The authors included the following sources of PAHs in the analysis: active smoking; residential tobacco smoke (typically from a spouse who smokes); indoor and outdoor air pollution; and grilled/smoked meat intake.

The most common sources of PAH exposure were tobacco smoke (from active or passive smoking) and grilled/smoked food intake. Based on the authors' multiple-PAH source models, breast cancer risk was found to be 20% higher among women exposed to smoking from a spouse and 29% higher among women exposed to synthetic fire log burning compared to women without such exposures. When the PAH exposures were grouped, the highest risk was from a group of indoor sources (active and passive smoking, grilled/smoked meat intake, plus stove/fireplace use) which resulted in a 45% increased risk of breast cancer among women so exposed. The authors conclude that exposure to multiple common PAH sources, particularly indoor sources, were associated with a 30% to 50% increase in breast cancer incidence in this study population. PAH exposure is a potentially modifiable breast cancer risk factor.