The ‘Healthy Worker Effect’ on Indexes of Total Mortality and Malignant Neoplasms Mortality for Nuclear and Chemical Workers: Meta-Analysis

Abstract

A meta-analysis of studies of the ‘Standardized mortality ratio’ (SMR, in % compared with the general population) indexes of overall mortality and mortality from all malignant neoplasms for nuclear workers (NW) from 15 countries (for 2007), as well as for workers dealing with the most toxic heavy metals (Hg, Cd, Pb, Cu) and beta-naphthylamine (a carcinogenic antioxidant previously used in the manufacture of paints) was carried out. For NW, a ‘Healthy worker effect’ (HWE) was found for both indexes (SMR = 62 (95 % CI: 56; 69) and 74 (95 % CI: 69; 78), respectively). The obtained SMR values for NW were compared with data for other professional groups (the results of meta-analyses and individual studies with maximum and minimum SMR values: from cosmonauts/astronauts, pilots and athletes, to work with chemical compounds in general or with their individual types (solvents, heavy metals, beta-naphthylamine), as well as with asbestos. It was found that the level of HWE for NW is comparable to that for one group of athletes and is significantly (1.30–1.45 times) higher than for chemical production personnel, although the combined data for NW is not final. For workers in the chemical industry as a whole, according to published meta-analyses, HWE was also found in SMR, but weak: the value for total mortality was 90 (95 % CI: 87; 92). At the same time, mortality from all malignant neoplasms compared with the population did not reveal a clear HWE, but was not increased either. The most harmful types of employment are, on the rise, work with heavy metals, in coal mines, with beta-naphthylamine and with asbestos. The data obtained eliminates the prevailing stereotypes and can improve the image of employment in the nuclear and chemical industries in general.