Intended for healthcare professionals


Ionising radiation in the workplace

BMJ 2015; 351 doi: (Published 20 October 2015) Cite this as: BMJ 2015;351:h5405
  1. Mark P Little, senior investigator
  1. 1Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892-9778, USA
  1. mark.little{at}

Low risk but not no risk

Information on radiation risk for cancer has come from several sources,1 in particular the Japanese atomic bomb survivors that comprise the Life Span Study cohort.2 It remains a controversial question whether there is a risk at low doses and low dose rates; although some have suggested the existence of thresholds below which there is no excess radiation risk or even beneficial (hormetic) effects of radiation exposure,3 this evidence has been disputed.4 The International Commission on Radiological Protection5 assumes, for regulatory purposes, that cancer risks can be linearly extrapolated from high radiation doses and high dose rates to low radiation doses and low dose rates by applying a dose and dose rate effectiveness factor (DDREF) of 2. However, the use of DDREF is controversial, and there is some evidence to suggest that excess cancer risks per unit dose do not fall in the lowest ranges of dose rate.6

In a linked article,7 the International Nuclear Workers Study (INWORKS) suggests significant risks associated with low dose rate occupational exposure to radiation in a combined cohort of 308 297 radiation workers from France, the United Kingdom, and the United States. This important study extends the follow-up of parts of a previous pooled analysis of nuclear …

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