Recently the results of a comprehensive epidemiological follow up study of cancer mortality in cohorts with occupational exposure to acrylamide was published.1 With the exception of a weak significance for a raised incidence of pancreatic cancer the study arrived by and large at the conclusion that there is “little evidence for a causal relation between exposure to acrylamide and mortality from any cancer sites”. The study updates and confirms an investigation 10 years earlier of the same cohorts.2 The analysis was based on standardised mortality ratios (SMRs) in comparison with United States national or relevant county mortality statistics. It exemplifies the shortcomings of epidemiological studies of this kind to detect moderate influences of specific causative factors on cancer mortality or incidence. The investigators state that they have carried out “the most definitive study of the human carcinogenic potential of exposure to acrylamide conducted to date”. The results, however, pose questions. Could unacceptable risks be detected? Which risks would have been expected?

For the workers in the United States the average cumulative exposure is given as 0.25 mg/m³.y. (We assume this to correspond to exposure of the whole factory staff to 0.25 mg/m³ for 365 8 hour working days). At an alveolar ventilation rate of 0.2 l/kg.min this exposure would mean a cumulative uptake of about 9 mg acrylamide per kg body weight. This dose corresponds to a lifetime (70 years) uptake of 0.35 μg/kg.d. According to the estimate of the United States Environmental Protection Agency3 this would correspond to a cancer risk of 1.6×10^-3. An estimate based on the multiplicative model4 would arrive at roughly a 3 times higher risk, 5×10^-3. With a cancer mortality in the western …

Professor G M Marsh gmarsh{at}vms.cis.pitt.edu