International study shows that low doses of radiation cause a small increase in leukaemia risk among nuclear workers

A multinational study coordinated by the International Agency for Research on Cancer (IARC), in collaboration with CREAL, an allied ISGlobal center, the US National Institute for Occupational Safety and Health (NIOSH), Public Health England (PHE), the French Institute de Radioprotection et Sûreté Nucléaire (IRSN) and the University of North Carolina in the US shows that protracted exposure to low doses of ionizing radiation can cause leukaemia. The study, published today in The Lancet Haematology, shows that the risk of death from leukaemia increases linearly with the radiation dose.

“This study provides the most precise evaluation to date of the risk of leukaemia following protracted low doses of radiation,” says Professor Elisabeth Cardis, Head of CREAL’s Radiation Programme, one of the study co-authors. “It shows that even the low doses of radiation received by nuclear industry workers can cause a small increase in leukaemia mortality and that the risk increases with increasing doses.”

Low-dose exposures are typical of environmental or occupational exposures, such as exposure of nuclear workers at their workplace, but also of medical exposures, such as patients undergoing multiple computed tomography (CT) scans through medical diagnostic procedures.

The study

Based on the strongest evidence currently available, the International Nuclear Workers Study (INWORKS), a follow-up of the previous 15-country study lead by Professor Cardis, evaluated the exposures of more than 300 000 nuclear workers in France, the United Kingdom, and the USA over the period 1943 and 2005.

The study assessed the risk of developing certain cancers, such as leukaemia, lymphoma, and multiple myeloma.

The results: exposure to ionizing radiation and risks

The study results highlight strong evidence for a positive association between exposure to ionizing radiation and risk of death from leukaemia and show that the risk of leukaemia increases linearly with radiation dose.

The risk associated with the exposure varies with the type of leukaemia; the risk was highest for chronic myeloid leukaemia, and there was no increased risk for chronic lymphocytic leukaemia.

The study shows little evidence of associations between exposure to ionizing radiation and mortality from multiple myeloma or lymphoma.

“Current standards used for radiation protection remain primarily based on acute high-dose exposures, derived from studies based on atomic bomb survivors in Japan,” says IARC Director Dr Christopher Wild. “This assessment of the carcinogenic impact of low-dose exposures strengthens the evidence on which to base radiation protection measures. These new findings are important when considering radiation exposure in different settings, including use in medical diagnosis.”

Reference

Leuraud, Klervi et al. Ionising radiation and risk of death from leukaemia and lymphoma in radiation-monitored workers (INWORKS): an international cohort study.The Lancet Haematology. June 22th. 2015.