Semen quality in welders exposed to radiant heat Jens

Several studies suggest that welding is detrimental to the male reproductive system. Welding fume and radiant heat are of interest as possible causal factors. This study investigates semen quality and sex hormone concentrations among 17 manual metal arc alloyed steel welders with a moderate exposure to radiant heat (globe temperature ranging from 31.1 to 44-8'C), but without substantial exposure to welding fume toxicants. During exposure to heat the skin temperature in the groin increased on average by 1-4°C (SE + 0O72'C). Sperm count and motile sperm count were non-significantly reduced among welders in comparison with two different reference groups. Within the group of welders the proportion of sperm with normal shape declined significantly after six weeks of exposure to heat and increased after a break in exposure. Sperm count and sperm concentration had the same pattern of intraindividual change in relation to exposure to radiant heat, but the changes were not statistically significant. No consistent changes in concentrations ofsex hormones were found. The welders investigated were more exposed to radiant heat than welders in general. The results suggest that the study group of welders experienced a reversible decrease in semen quality, most likely caused by a moderate exposure to radiant heat (about five hours a day through several weeks). It remains to be established if even lower levels ofexposure to radiant heat in the general population of welders has any impact on semen quality and fertility. Several Danish studies suggest that welding work is detrimental to the male reproductive system,'-5 but these findings have not been confirmed by other studies.' If real the magnitude of risk of reduced reproductive performance in terms ofreduced semen quality, delayed conception, and reduced fertility appears to be small (odds ratio ranging from 1 1 to 2-0). In accord with this only moderate deterioration (averaging 10-25%) in semen quality has been encountered among mild steel welders.5 Several types ofexposures associated with welding may represent a hazard to the male reproductive system. As well as water soluble toxic substances in welding fume particulates, raising the temperature of the testes might be ofsignificance. Animal studies and experimental studies on human subjects exposed to short term, heavy local, or systemic heat strain have established heat as a potent suppressor of spermatogenesis."' The threshold of long term exposure to radiant heat for impairment of spermatogenesis is, however, unknown. In fact, it has been disputed whether heat exposure in the occupational environment is associated with any significant impairment of male reproductive function."4 This study takes advantage of an opportunity to investigate a group of welders with long term moderate exposure to radiant heat without any substantial exposure to welding fume toxicants. The purpose was to examine whether exposure to radiant heat at magnitudes occurring among welders affects semen quality. Welders selected for this study undoubtedly have a higher exposure to radiant heat than welders in general. Accordingly, a positive result would encourage investigation of the "heat hypothesis" in further studies aimed at identifying reproductive risk factors among male welders, whereas a negative result would practically rule out a role for exposure to radiant heat. Semen quality was examined before, during, and after exposure to radiant heat. This longitudinal design in which each person acted as his own control was chosen to overcome obvious methodological drawbacks associated with a cross sectional design. Nevertheless, semen quality of heat exposed welders was also compared with two reference groups investigated by the same methods in previous sperm studies. Subjects and methods EXPOSURE, SELECTION OF PARTICIPANTS, AND SEMEN SAMPLING The study was undertaken at a plant which manufactures boilers for power stations. Welding of sockets on headers in chromium alloyed steel (X-20 CRMDV-121; 10-12 5% and 0-3-08% content of chromium and nickel respectively) was performed by Department of Occupational Medicine, Hospital of Aalborg, Denmark J P Bonde 5 group.bmj.com on April 13, 2017 Published by http://oem.bmj.com/ Downloaded from