Exposure to chemicals found in industrial emissions may increase male infertility odds
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ANAHEIM, Calif. — Industrial emissions containing endocrine-disrupting chemicals may negatively affect the fertility of men, according to a speaker here.
In preliminary findings from a population-based cohort study, researchers found men exposed to multiple classes of endocrine-disrupting chemicals above the 75th percentile had lower sperm counts and a greater likelihood for azoospermia compared with men exposed to concentrations of the chemicals below the 25th percentile.
“Male fertility appears to be adversely impacted by exposure to endocrine-disrupting chemicals from industrial sources,” Joemy Ramsay, MS, PhD, assistant professor in the division of urology, department of surgery at University of Utah, told Healio. “A male factor is involved in 50% of all couples with infertility; however, the cause of infertility is unknown in at least 50% of men. Exposure to air pollution and endocrine-disrupting chemicals, in particular, are one potential cause.”
Researchers analyzed data from 21,236 men participating in the Subfertility, Health and Assisted Reproduction (SHARE) cohort who underwent semen analysis from 2005 to 2017. Men were considered to have azoospermia or subfertility if they had sperm concentration of less than 15 million/mL and a total sperm count of less than 39 million. Data from the Utah Population Database was used to identify residential locations for each participant from administrative records. Exposure to endocrine-disrupting chemicals was identified as living within 50 km of an industrial facility emitting a chemical in the 5 years prior to sperm analysis. Researchers also conducted logistic regression analysis for 12 chemical groups that more than 100 men were exposed to.
Of the study cohort, 98% lived within 50 km of an industrial facility. Men exposed to 2,4-dinitrotoluene, acrylonitrile, dibutyl phthalates, hexachlorobenzene and polychlorinated biphenyls above the 75th percentile had significantly lower sperm concentrations and sperm count compared with men exposed to the same chemicals below the 25th percentile. Lower total motile count was observed for men exposed to higher levels of 2,4-dinitrotoluene, acrylonitrile, hexachlorobenzene and polychlorinated biphenyls, and lower total progressive motile count was observed among men exposed to higher levels of 2,4-dinitrotoluene and acrylonitrile compared with those exposed to lower levels.
Men were more likely to have azoospermia if they were exposed to levels above the 75th percentile of carbon disulfide (OR = 1.95; 95% CI, 1.51-2.52), di(2-ethylhexyl) phthalates (OR = 1.41; 95% CI, 1.15-1.71), ethylene glycol (OR = 1.63; 95% CI, 1.27-2.07), methylene chloride (OR = 1.75; 95% CI, 1.37-2.25), silver (OR = 1.61; 95% CI, 1.3-1.99), tetrachloroethylene (OR = 1.84; 95% CI, 1.45-2.33), toluene (OR = 1.5; 95% CI, 1.17-1.92) and trichloroethylene (OR = 2.06; 95% CI, 1.61-2.63) compared with men exposed to the 25th percentile of the same chemicals.
Ramsay said the data are preliminary, and more research must be performed. Additionally, she said strong clinical recommendations are difficult to make due to several factors.
“Many chemicals lack toxicology data that can be used to implement safe exposure levels,” Ramsay said. “Thousands of chemicals are in common use; however, only a fraction of them have undergone significant toxicological evaluation. In our analysis, 40% of the included chemicals did not have a published limit for exposure in air, and for those that did, many were not assessed for reproductive toxicity. Recent advances in computational toxicology, including in silico and high throughput testing, have made it easier to efficiently and credibly evaluate chemical safety; however, these advances are often slow to be incorporated into policy.”
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Ramsay J, et al. O-20. Presented at: ASRM Scientific Congress & Expo; Oct. 22-26, 2022; Anaheim, California.
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