Radiation Risk of Malignant Neoplasms in Organs of Main Deposition for Plutonium in the Cohort of Mayak Workers with Regard to Histological Types

Abstract

This paper presents the results of analyses of the incidence of malignant neoplasms in lung, liver, and bone and associated connective tissues among Mayak nuclear workers exposed to both internally incorporated plutonium and to external gamma radiation. The study cohort included 22,373 individuals employed at the reactors and radiochemical and plutonium production facilities of the Mayak nuclear complex during 1948-1982 and followed up to the end of 2004. All analyses were carried out by Poisson regression, and the doses used were derived using a recently available update of organ doses, Mayak doses-2008. There was clear evidence for the linear association between internal plutonium dose and the risk of lung cancer. For males, there was evidence of a significant internal plutonium dose response for all histological types of lung cancer evaluated (adenocarcinoma, squamous-cell, and other epithelial); the estimated excess relative risk (ERR)/Gy for adenocarcinoma was the largest (ERR/Gy = 32.5; 95% CI: 16.3; 71.9), about 11-fold higher than that for squamous-cell lung cancer (ERR/Gy = 3.1; 95% CI: 0.3; 9.1). The relationship between liver cancer risk and plutonium exposure was best described by a linear-quadratic (LQ) function, but the LQ effect was diminished after restricting internal doses <2 Gy. Hepatocellular cancer was the most frequently observed type of liver cancer associated with internal plutonium exposure, and hemangiosarcomas were exclusively observed only at high internal plutonium doses (>4 Gy). For malignant neoplasms of bone and associated connective tissues, the trend was not statistically significant in relation to internal plutonium dose, but a statistically significantly higher risk (RR=13.7; 95% CI= 3.0; 58.5) was found among unmonitored female plutonium workers who were employed in the most hazardous plutonium production facility commissioned prior to 1950.

Solid cancer incidence other than lung, liver and bone in Mayak workers: 1948–2004

“…These studies have demonstrated significant association between cancer and non-cancer diseases and exposure to internal plutonium and external gamma ray. Risks of morbidity from cancers of the lung, liver and bone – the organs of primary plutonium deposition – have been reported previously (Labutina et al , 2013). The focus of this paper is to present results for incidence of solid cancers other than those of the lung, liver and bone (here after referred to as ‘other solid cancers'), in relation to external and internal plutonium exposure among radiation workers in the Mayak PA cohort.…”

“…The cohort design, data collection and methods used to determine the vital status have been described in detail previously (Koshurnikova et al , 1999; Labutina et al , 2013). We summarise here some of the main aspects.…”

“…The data were analysed using the same methods as in previous studies of this cohort (Shilnikova et al , 2003; Sokolnikov et al , 2008; Labutina et al , 2013). The Poisson regression was used to test for an association between incidence from other solid cancers and exposure to both external gamma-ray using Hp(10) dose (Gy) and plutonium using internal liver dose (Gy).…”

Radiation Effects on Mortality from Solid Cancers Other than Lung, Liver, and Bone Cancer in the Mayak Worker Cohort: 1948–2008

“…With almost 60 years of follow-up and individual dose estimates, the MWC provides a unique opportunity to study the effects of both internal Pu and prolonged low dose rate external gamma exposures in a working age population of men and women. The cohort has been used to describe radiation effects on cancer risks including studies of internal and external dose on cancer at the sites of primary Pu deposition (lung, liver, and bone surface) [1–4] and other solid cancer sites and leukemia [5,6] as well as some non-cancer health effects [7–9]. In this paper we consider radiation effects on the risk of solid cancer mortality at sites other than lung, liver, or bone surface since these three sites receive substantial doses from incorporated Pu while for other sites it is known that there is little or no internal exposure arising from Pu [10–12].…”

Radiation pathology: From thorotrast to the future beyond radioresistance

“…Shortly after the end of World War II, the USSR began plutonium production at a nuclear weapons complex (Mayak PA) in the Chelyabinsk region. Mayak PA workers employed at radiochemical facilities and plutonium extraction facilities were exposed to external γ‐rays in combination with radiation from inhaled plutonium‐239 . The Semipalatinsk Test Site (STS) of Kazakhstan was the primary nuclear testing site for USSR.…”