Dose-response analyses of osteonecrosis in New Jersey radium workers point to roles for other alpha emitters

A previous study of 25 radium workers reported radium osteonecrosis to be common down to that study's lower limit of detection of 226Ra. This paper reanalyzes those data using Poisson and linear regression to obtain quantitative dose-response estimates for radium osteonecrosis. A quadratic, supralinear response of the necrosis ratio to skeletal dose and preterminal 226Ra burden was observed at a high level of statistical significance. At low dose the response was linear. Clearly observable necrosis, that appearing in 4% of tissue blocks, was seen in femurs at approximately 0.8 Gy skeletal dose. Comparable effects from plutonium in spongy bone might therefore be expected in the 0.01-0.02 Gy dose range. Prediction equations are presented for preterminal 226Ra burden, for skeletal dose, and, at low doses where the response can be taken as linear, for dose from and uptakes of both 226Ra and 228Ra. Male New Jersey workers in the radium refinery were observed to have necrosis not explained by the 226Ra uptakes, but compatible with skeletal doses from other internal emitters, in the range 0.25-1.2 Gy lifetime dose acquired per year of employment. 210Po, inhaled directly or from inhaled 210Pb, is the most likely source of this dose.