One of the greatest challenges in teasing out environmental links to breast cancer is the long latency period between a woman’s exposure to a toxic and the development of a tumor. It would be unethical, of course, to conduct experiments that randomly expose one group of people to toxics to observe the effects in comparison to unexposed controls. So researchers often turn to unexplained discrepancies between populations—such as communities with disproportionately high or low breast cancer rates—for clues.
Such an inconsistency sparked the founding of Silent Spring Institute, when women living on Cape Cod were discovered to have significantly higher rates of breast cancer than women in the rest of Massachusetts. In the same report, a city just west of Boston—Newton, Massachusetts—was shown to have a marked unevenness in breast cancer rates, which ranged from 22 percent below the state average to 55 percent above. The Cape Cod Breast Cancer and Environment Study and the Newton Breast Cancer Study became two of the Institute’s earliest initiatives.