Is your reproductive system in danger? (Science & Technology, Sept. 14) was misleading. Rates of breast cancer are stable, not "soaring." The increased incidence of this disease from 1980 to 1992 was due to improved detection methods. Screening mammography became widespread, and more low grade tumors were detected; note that mortality rates were level during this same period and now show a slight decline.
The article also alludes to a report by John Brock, who found an association between high levels of polychlorinated biphenyls (PCBS) and non Hodgkin's Iymphoma in a small, retrospective study. There are many other studies that found decreased incidence of cancer in workers who had been occupationally exposed to PCBS for decades.