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IDAEA-CSIC has identified more than 40 chemical substances in the semen of adult men after assessing the presence of 2,000 compounds using a pioneering methodology
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The study shows the ability of sweeteners, insecticides or bisphenols to reduce sperm concentration, motility and vitality
Continuous exposure to harmful chemical compounds influences spermatogenesis. | iStock
A pioneering methodology developed by the Institute of Environmental Assessment and Water Research (IDAEA) of the Spanish National Research Council (CSIC), in collaboration with the LABERCA Unit of the French National Research Institute for Agriculture, Food and Environment (INRAE) and the Nutrition Unit of the Universitat Rovira i Virgili (URV) in Tarragona, has identified 42 everyday chemical compounds in human semen. The results, published in the journal Exposome, provide a detailed overview of overall exposure to toxic compounds and their potential impact on male reproductive health.
Infertility affects 15% of the world’s population, with male factors responsible for 40–50% of these infertility cases. In this issue, which has worsened in recent decades, factors linked to environmental exposures and lifestyle are emerging as key variables for reproductive health.
“Although our study does not allow us to establish causal relationships between the presence of multiple chemical substances and spermatogenesis, it does provide evidence of associations between exposure to these compounds and semen quality,” explains Montse Marquès, IDAEA-CSIC researcher and lead author of the study.
To assess their impact, the new study evaluates the chemical exposome: the set of chemical substances to which the population is exposed, using an innovative high-resolution mass spectrometry methodology. This technique determines the exact mass of compounds with a precision greater than 0.001 atomic mass units, allowing the distinction between substances that, although they appear identical, have different chemical compositions.
To determine the presence of chemical compounds, the research analysed semen, blood and urine samples from a study group of 48 healthy men aged between 18 and 40 years, living in Tarragona. The research team applied a broad-spectrum chemical screening to analyse the range of chemical substances to which participants were routinely exposed. After screening for more than 2,000 organic compounds, the technique detected 42 substances in semen, 42 in urine and 48 in blood. The substances belonged to complex mixtures including artificial sweeteners, insecticides, per- and polyfluoroalkyl substances (PFAS), flame retardants, food-related compounds, pharmaceuticals and markers of tobacco consumption.
“Traditionally, studies focus on specific families of toxic compounds. In this work, thanks to high-resolution mass spectrometry, we applied a screening capable of tracking thousands of compounds simultaneously in three different biological matrices: semen, blood and urine,” explains Marquès.
Chemical compounds and sperm quality
The analysis showed that some of the toxic compounds detected negatively altered various parameters of semen quality. For example, acesulfame (a widely used artificial sweetener), bisphenol-S (a compound used in plastics and resins), the insecticide nitenpyram or certain industrial and pharmaceutical surfactants were negatively associated with total sperm count, morphology and concentration. The flame retardant triethyl phosphate (used as a fire-retardant substance in building materials, vehicles or electronics) was linked to a lower semen volume, while another additive used in tyre manufacturing was associated with a reduction in motility and vitality.
The study also confirmed negative associations already described in the scientific literature for tobacco-derived compounds such as nicotine and cotinine, and for persistent perfluorinated substances used in cookware, packaging and clothing, among other products. The results reinforce the evidence that the chemical exposome can influence the formation and development of sperm cells (spermatogenesis) and contribute to the decline in male fertility observed in recent decades.
“We have found that seminal plasma is a matrix of great interest for studying the chemical exposome in relation to semen quality, as it allows the identification of contaminant mixtures that may go unnoticed in blood or urine but are closely linked to reproductive function,” states German Cano-Sancho, researcher at the LABERCA Unit of INRAE and first author of the study.
This approach makes it possible to optimise the use of biological samples and obtain a much more complete picture of real population exposures, opening new avenues for research in environmental and reproductive health.
Cano-Sancho, G., Gutiérrez-Martín, D., Sánchez-Resino, E, et al. 2025. Multi-matrix chemical exposome characterization and its association with semen quality. Exposome, Volume 5, Issue 1, osaf014. DOI: 10.1093/exposome/osaf014
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