Multiple studies have demonstrated a global population-wide decline in semen quality, with sperm concentrations having fallen 50% over the past 50 years. Several metal and metalloid ("metal(loid)") compounds are known to have testicular toxicity, raising concerns about their contribution to rising infertility. In the male reproductive tract, metal(loid)s can reduce semen quality and disturb function both directly, by inducing tissue damage, and indirectly, by disrupting hormone production and secretion. This study assessed associations between 15 creatinine-adjusted metal(loid)s and 7 measures of semen quality among 413 reproductive-aged men recruited from 16 U.S. counties between 2005-2009. Multi-metal(loid) multivariable linear regression models estimated associations between semen quality endpoints and urinary concentrations of chromium, cobalt, copper, molybdenum, selenium, zinc, antimony, arsenic, barium, cadmium, lead, thallium, tin, tungsten, and uranium. LASSO regression was employed to select model variables and account for multicollinearity of the metal(loid)s. A positive association was observed between tin and sperm morphology (β = 4.92 p = 0.045). Chromium (β = 1.87, p = 0.003) and copper (β= -1.30, p = 0.028) were positively and negatively associated with total sperm count, respectively. With respect to DNA fragmentation, cadmium (β = 12.73, p = 0.036) was positively associated and chromium was negatively associated (β = -5.08, p = 0.001). In this cohort of U.S. population-based men, there was evidence of both positive and negative associations between specific metal(loid)s and semen quality. Additional research is needed to determine interactions between metal(loid)s within a mixture, consistent with typical human exposure, and identify sperm effects resulting from cumulative metal(loid) exposures.
Reproductive toxicology (Elmsford, N.Y.). 2021 Oct 09 [Epub ahead of print]
Francesca M Branch, Melissa J Perry, Zhen Chen, Germaine M Buck Louis
Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, 950 New Hampshire Ave. NW, Washington, DC, 20037, United States. Electronic address: ., Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, 950 New Hampshire Ave. NW, Washington, DC, 20037, United States. Electronic address: ., Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, 6710B Rockledge Drive Executive Boulevard, Bethesda, MD 20892, United States. Electronic address: ., College of Health and Human Services, George Mason University, 4400 University Drive, MS 2G7, Fairfax, VA 22030, United States. Electronic address: .