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Scientists comment on a French court ruling that claims cosmic radiation was a factor in an air stewardess case of breast cancer.
Prof Richard Wakeford, Professor in Epidemiology, Centre for Occupational and Environmental Health (COEH), University of Manchester, said:
“Ionising radiation is a recognised cause of female breast cancer, but the probability of radiation being the cause of a specific case of breast cancer rather than some other factor(s) depends on the dose of radiation received (and related factors, such as the age at which the dose is received). Epidemiological studies have established that high doses of radiation can cause female breast cancer, but the evidence for low doses causing breast cancer is equivocal because of the difficulty in distinguishing any radiation “signal” against the ever present background statistical “noise” produced by other causal factors.
“One naturally occurring source of radiation exposure is cosmic radiation from the Sun and beyond, and at high altitudes such as in aircraft, exposure to cosmic radiation is increased because of reduced shielding by the atmosphere. However, the additional annual doses of radiation received by aircrew are low, and the annual dose to the breast is just a few millisievert (mSv) above the annual dose from natural background radiation of 1-1.5 mSv that would be received at sea level (of which about 0.3 mSv is from cosmic radiation).
“The probability that a specific case of female breast cancer can be attributed to a particular dose of radiation can be estimated through a “probability of causation” calculation. These calculations form the basis of the UK Compensation Scheme for Radiation-Linked Diseases (http://www.csrld.org.uk/) and similar compensation schemes.
“A “probability of causation” calculation can be applied to the circumstances of the French flight attendant to provide an estimate of the probability that her breast cancer was caused by the additional cosmic radiation exposure incurred in her job. From media reports, she was born in 1967 and was employed as aircrew during 1989-2019. During this period, she may have received an additional dose of cosmic radiation of around 4 mSv every year, although this is likely to be at the upper end of of the annual additional dose received. These data may be input to a “radiation risk calculator”, such as that provided by the US National Cancer Institute, NCI (https://radiationcalculators.cancer.gov/radrat/). Using this NCI “radiation risk calculator”, the probability of additional annual doses of radiation of 4 mSv to the breast causing breast cancer in the remaining expected lifetime from 1989 is around 0.25%, which compares with the baseline risk of breast cancer during this period (in the absence of the additional occupational exposure) of around 13%. It is apparent from these risk estimates that on the “balance of probabilities” (the basis upon which a British court would make a decision on causation) it is unlikely that the specific case of breast cancer can be attributable to the additional dose of cosmic radiation received from occupational exposure to cosmic radiation.”
Prof Jim Smith, Professor of Environmental Science, University of Portsmouth, said:
“For an individual case, it is impossible to determine whether or not a cancer was caused by radiation. Current radiation protection guidance assumes that any small dose can potentially cause cancer – but the lower the dose the lower the risk. From the known cosmic ray dose to air crew, and based on this hypothesis, we might expect that air crew regularly flying at high altitudes would have a small additional risk of cancer.
“Unfortunately, cancer is a very common disease with Cancer Research UK estimating that nearly half of us will contract cancer at some point in our lives. So, at the (relatively) low radiation doses air crew are exposed to, it is difficult statistically to see increases in cancer rates due to cosmic radiation. Complications in these studies for air crew include particular lifestyle factors. For example, increased sun exposure may lead to greater skin cancer incidence and working night-shifts and irregular sleeping patterns can potentially affect a range of health outcomes including cancer.”
References:
Cancer risk statistics | Cancer Research UK
Module 3. Diseases and Shift Work | NIOSH | CDC
Declared interests
Professor Richard Wakeford: “is a member of the Technical Working Party of the UK Compensation Scheme for Radiation-Linked Diseases”.
Prof Jim Smith: I have in the past (over 10 years ago) done small consultancy projects for the nuclear industry. I don’t currently do any consultancy or have any nuclear industry links. I am a Director of The Chernobyl Spirit Community Interest Company, a social enterprise supporting Ukraine with sales of ATOMIK spirits from Chernobyl affected areas.