Characteristics of the Cohort of Workers at the Mayak Nuclear Complex

TLDR

The Mayak worker cohort offers a unique opportunity to estimate long‑term health effects of chronic low‑dose‑rate external gamma and internal plutonium radiation, but several issues must be resolved before credible risk estimates can be derived. The study aims to resolve key methodological issues, such as establishing suitable comparison groups and disentangling internal and external exposure effects, to enable reliable risk estimation. A registry of 18,830 workers hired 1948‑1972 was assembled, documenting external gamma doses (tenths of mGy to ~10 Gy) and internal plutonium burdens (measured in ~30 % of members, up to ~260 kBq). Among the cohort, 25 % were women, vital status is known for ~90 %, 5,118 deaths have been recorded, and causes were ascertained for 97 % of deaths. The registry is maintained at Branch No.

Abstract

At Branch No. 1 of the Russian State Research Center "Biophysics Institute", a registry has been created of workers at the "Mayak" Production Association, the first nuclear complex in Russia. This registry includes 18,830 persons hired at Mayak's nuclear reactors and radiochemical and plutonium production plant between 1948 and 1972. Twenty-five percent of these workers are women. As of December 31, 1994, the vital status is known for approximately 90% of the cohort members. A total of 5,118 persons have died. The cause for 97% of total deaths has been ascertained. The cohort members were exposed to both external gamma radiation and internal radiation from incorporated plutonium. The plutonium body burden has been measured in 30% of the cohort members with potential for plutonium exposure. External gamma-ray doses were in the range from tenths of milligrays to about 10 Gy, and plutonium body burdens were up to about 260 kBq. In view of the nature of the Mayak worker cohort, it has the potential to provide reasonably precise, quantitative estimates of the long-term health effects associated with chronic low-dose-rate exposure to external gamma radiation as well as internal radiation from plutonium. However, a number of issues must be addressed before credible risk estimates can be obtained from this cohort. These issues include the development of an appropriate internal comparison group and/or external rates and separating of the effects of internal and external exposures on risk estimates.