ACCOUNTING FOR THE CARCINOGENICITY OF AIRBORNE PARTICLES

Findings from epidemiological studies conducted as early as the 1950s suggest that air pollution might explain the higher rates of lung cancer seen in urban areas. Solid evidence implicating a specific agent to account for that effect is lacking, but attention has been focused on particulate matter (PM) because it contains known carcinogens, including metals and polycyclic aromatic hydrocarbons (PAH). Two articles in this issue examine the evidence that some constituent of particulate air pollution causes lung cancer. Harrison and colleagues (p. 799) take a creative, indirect approach to the problem by comparing the lung cancer rates observed in the large American Cancer Society cohort to the rates expected in the same group based on its estimated exposure to fine particles and published risk coefficients for arsenic, chromium, nickel, and PAH. They find that the observed and expected rates are similar. Although the authors point to uncertainties in …