Remembering Alice Stewart. (In Memoriam).

Few issues have perpetuated as much controversy among scientists and politicians as that of the health implications of low-level exposure to ionizing radiation. British physician and epidemiologist Alice Stewart, who died 23 June 2002 at age 95, was among the pioneers whose work helped spawn the debate nearly a half-century ago, just as nuclear weapons development was taking off. Although long regarded as a pariah by the medical/scientific establishment for her controversial views on radiation effects, Stewart became known to many as a visionary who worked indefatigably to advance the understanding of radiation health effects and cancer etiology.

During the 1950s, while working in the Department of Social Medicine at Oxford University, Stewart and her colleagues noticed a sharp rise in childhood leukemia at a time when antibiotics were contributing to a decline in childhood mortality from infections. With a modest grant of 1,000 [pounds sterling], Stewart launched the Oxford Survey of Childhood Cancers, which interviewed British women whose children had died of lymphatic leukemia and compared the medical records of those children with those of age- and sex-matched healthy children from the same regions during the period 1953-1955. Stewart first reported her findings in a 1956 paper published in The Lancet, showing that children who died of cancer had received prenatal X rays twice as often as healthy children, and at a mere fraction of the exposure level considered safe at the time.

Stewart's findings sparked vehement attacks not only from the medical profession--which had become enamored of X-ray technology, using it frequently--but also from the nuclear industry, which had long assured the public that low-level radiation was harmless. Critics cited studies of A-bomb survivors from Hiroshima and Nagasaki suggesting that medical X rays were safe regardless of age at the time of exposure. The survivor data were considered at that time to be the gold standard for assessing the health effects of radiation exposure, and Stewart's findings were regarded by many as specious for about two decades. In the words of Arthur C. Upton, fellow emeritus of the Collegium Ramazzini, an international community of scholars that promotes the study of occupational and environmental health issues around the world, "To many in the nuclear power industry, the medical profession, and the radiation protection community, her views [were] too far outside the scientific mainstream to be fully credible. To others, however, Alice [was] a trusted champion of the precautionary principle."

Then, working with Oxford statistician George Kneale in the 1970s, Stewart provided evidence suggesting that workers at the Hanford Nuclear Site in Richland, Washington, were dying of cancer induced by occupational radiation levels that were well below the exposures considered safe at that time. Stewart argued that the A-bomb survivor data gave a biased picture of radiation effects because they represented an atypically robust group (those who had survived the blast and subsequent devastation). Stewart also inferred that, although many of the survivors escaped cancer, many others went on to die of what was eventually identified as radiation-related immune system damage, resulting in aplastic anemia and susceptibility to infections. Stewart's reanalysis of the survivor data further implied that the radiation protection committees of the time had grossly underestimated the number of cancers caused by background radiation and other low-level radiation sources.

Stewart, a fellow of the Royal College of Physicians (the youngest woman ever elected) and cofounder of the British Journal of Industrial Medicine, authored more than 400 scientific papers during her prolific career. Her pioneering work in industrial epidemiology and radiation health effects was recognized when she was made a fellow of the Royal College of Medicine and Public Health in 1985. The following year, she received the Right Livelihood Award (the socalled "alternative Nobel Prize" presented by the Swedish Parliament), which credited her for "an essential contribution to making life more whole, healing our planet, and uplifting humanity." A fellow of the Collegium Ramazzini, Stewart also received the Ramazzini Award for epidemiology in 1992. Four years later, Birmingham University made her an honorary professor.

Stewart's work contributed greatly to our understanding of the potential hazards that small doses of radioactivity could pose to human health and the quality of life. Her studies linking child cancers with fetal X rays left an indelible mark on the medical care of pregnant women, and her studies of adult cancer rates among the Hanford nuclear workers eventually led to worker compensation legislation. Says Upton, "She will long be honored and celebrated for the Oxford Survey and for the stimulus that her work has provided to the fields of radiation protection and public health."