Lung cancer risks from plutonium: an updated analysis of data from the Mayak worker cohort.

Workers at the Mayak nuclear facility in the Russian Federation offer a unique opportunity to evaluate health risks from exposure to inhaled plutonium. Risks of mortality from lung cancer, the most serious carcinogenic effect of plutonium, were evaluated in 14,621 Mayak workers who were hired in the period from 1948-1982, followed for at least 5 years, and either monitored for plutonium or never worked with plutonium. Over the follow-up period from 1953-2008, there were 486 deaths from lung cancer, 446 of them in men. In analyses that were adjusted for external radiation dose and smoking, the plutonium excess relative risk (ERR) per Gy declined with attained age and was higher for females than for males. The ERR per Gy for males at age 60 was 7.4 (95% CI: 5.0-11) while that for females was 24 (95% CI: 11-56). When analyses were restricted to plutonium doses <0.2 Gy, the ERR per Gy for males at age 60 was similar: 7.0 (95% CI: 2.5-13). Of the 486 lung cancer deaths, 105 (22%) were attributed to plutonium exposure and 29 (6%) to external exposure. Analyses of the 12,708 workers with information on smoking indicated that the relationship of plutonium exposure and smoking was likely sub-multiplicative (P = 0.011) and strongly indicated that it was super-additive (P < 0.001). Although extensive efforts have been made to improve plutonium dose estimates in this cohort, they are nevertheless subject to large uncertainties. Large bioassay measurement errors alone are likely to have resulted in serious underestimation of risks, whereas other sources of uncertainty may have biased results in ways that are difficult to predict.

Relative role of plutonium excretion with urine and feces from human body.

The ratio of plutonium content in 35 pairs of daily fecal and urine samples from 19 former MAYAK workers several decades after the end of occupational exposure was measured in clinical conditions. No dependence of the ratio Pu(feces)/Pu(urine) on plutonium aerosol transportability, sex, and age of workers was revealed in the late times after the end of occupational exposure. It was found that at the late times after the end of occupational exposure, the ratio of feces/urine is characterized by the lognormal distribution with the median value, 0.57, and error for this index characterized geometric deviation, sigmag = 1.12 Urinary and fecal excretions were analyzed after chronic exposure to inhaled plutonium compounds of different transportability for another group of 345 workers. During 500-16,000 d after the started chronic inhalation, plutonium biokinetic model ("Doses-2000") used in Southern Ural Biophysics Institute (SUBI) and based on the ICRP Publication 66 overestimated the feces/urine ratio by an order of magnitude as compared with the observed values. It indicates a necessity for further improvement of the biokinetic model used in SUBI.

Successful DTPA therapy in the case of 239Pu penetration via injured skin exposed to nitric acid.

This paper presents results of the radiological study and DTPA therapy for a worker exposed to a plutonium nitrate solution. Plutonium levels were measured in excreta, blood, plasma and wound for several weeks. Plutonium renal clearance ranged from 110-190 ml min(-1) to 3-4 ml min(-1) at different stages of chelation therapy. Plutonium absorption into blood from the injured skin amounted to 4.3%. As a result of intensive therapy, 96% of absorbed plutonium was successfully excreted.