Letters to the Editor Re: "leukemia following Occupational Exposure to 60-hz Electric and Magnetic Fields among Ontario Electric Utility Workers" and "cancer Risks Associated with Occupational Exposure to Magnetic Fields among Electric Utility Workers in Ontario and Quebec,

I read with great interest the recent paper by Miller et al. (1) on the risk of leukemia among Ontario electric utility workers. Their paper appears to be an addendum to the paper published previously by The'riault et al. (2) on cancer risks among electric utility workers in Ontario, Quebec, and France. The'riault et al. presented data on the risk of occupational exposure to extremely low frequency magnetic fields and found a higher risk for leukemia mainly in Ontario Hydro workers. Miller et al. present data from the same study but only for Ontario, and they add 5 cases of leukemia to the 45 cases studied by Theiiault et al. and consider possible confounders not taken into account in the The'riault et al. paper (2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid). Results from electric field measurements taken by means of the model 378108 Positron personal exposure meter (Positron Industries, Montreal, Quebec, Canada) were also considered by Miller et al. to supplement the data on magnetic fields presented by The'riault et al.