A major study funded by Hydro-Quebec, Ontario Hydro and a French utility has found a link between the magnetic fields generated by electric currents and leukemia among utility workers, reports the Gazette.

“We believe our results speak for an association between occupational exposure to magnetic fields and at least one type of leukemia,” say the authors, led by Dr Gilles Theriault of McGill University.

The study adds to mounting evidence of a cancer risk caused by magnetic fields, but the link isn’t conclusive, say the researchers. The study was released March 30 and looked at the health of 223,000 utility workers. A study in 1979 found that children living near high-current power lines had an increased risk of leukemia.

Workers with above-average exposure to magnetic fields were three times more likely to develop acute myeloid leukemia than less-exposed workers, the study found. Acute myeloid leukemia is one of the most common forms of leukemia among adults.

The study also found more brain cancer among workers exposed to high levels of magnetic fields. But because of the small number of cases found, the results are not considered statistically significant.