Epidemiology versus Animal Experiments
The revival of interest in epidemiology has been especially important for cancer research. Doctors now know much more about the causes and 80-90% of cases are considered potentially preventable.1 Population studies have proved so valuable that an editorial in the medical journal Clinical Oncology described the epidemiologist as the most important member of the cancer research team.48 Epidemiology has shown that differences in cancer between communities and between people are associated with differences in the local environment or the behavior or genetic constitution of individuals. According to Richard Doll,19
“The knowledge gained in this way has led, directly or indirectly, to nearly all the steps that have been taken to reduce the incidence of cancer in practice.”
The great majority of cancer-causing agents were first discovered from their effects on people following widespread use rather than by experiments on animals.19 It is also revealing that the 1980 United States Congress Office of Technology Assessment Report into the causes of cancer, relied far more on epidemiology than laboratory tests because, its authors argued,23 these “cannot provide reliable risk assessments.” Nevertheless, animal experiments have consistently been allowed to undermine epidemiological findings, often with disastrous results.
The failure to induce lung cancer in animals by forcing them to breathe tobacco smoke, cast doubt on the results of human studies, delaying health warnings for years and costing thousands of lives. Summing up nearly two years of experiments, the British Empire Cancer Campaign reported that mice, rabbits and other animals who were exposed to tobacco derivatives by direct inhalation, feeding, injection into the lungs and skin painting developed no signs of cancer.24 And a year
later, in 1957, American pathologist Eric Northrup concluded in his book Science Looks at Smoking that “(the) inability to induce experimental cancers, except in a handful of cases, during 50 years of trying, casts serious doubt on the validity of the cigarette-lung cancer theory.”
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