A study published in Frontiers in Endocrinology links insecticide exposure to lower sperm concentration in men.
Researchers analyzed semen and urine samples from 179 men at a reproductive clinic in Jinan, China. They found that men with high levels of neonicotinoid insecticides had a 27% lower sperm concentration compared to those with low levels.
Neonicotinoids are commonly used in agriculture to control pests. These chemicals disrupt the nervous systems of insects. They can be applied directly to plants or as seed coatings before planting.
The study examined four neonicotinoids: imidacloprid, acetamiprid, clothianidin, and thiamethoxam. It also looked at their breakdown products. The researchers studied these chemicals together since people often encounter mixtures rather than single insecticides.
Desnitro-imidacloprid, a breakdown product of imidacloprid, accounted for over 40% of the decline in sperm concentration linked to the mixture. This research adds to ongoing investigations into how pesticides affect sperm counts.
The study revealed some pesticide breakdown products were more concentrated in semen than urine. Urine tests are typically used for chemical exposure assessment because substances can be excreted through urine. However, the researchers noted that urine measurements might not fully reflect levels present in semen.
This distinction is important because urine reflects recent exposure while semen quality may indicate longer-term exposure effects. John Meeker, a professor at the University of Michigan School of Public Health, pointed out limitations regarding sample timing.
He suggested collecting multiple urine samples before obtaining a semen sample could improve accuracy when assessing exposure and sperm quality, especially at low concentrations.
The authors called for long-term studies to clarify the relationship between neonicotinoid exposure and male reproductive health and inform regulatory limits.
Sperm concentration is one measure of semen quality and impacts male fertility assessments. Poor semen quality has been linked to other health issues as well.
A 2016 study mentioned found that men with male-factor infertility faced higher risks for certain health conditions after their fertility assessment. Meeker cautioned that while a 27% difference might not affect every man’s fertility, it could have significant implications for those already near subfertile ranges.
Shanna Swan, an epidemiologist at Mount Sinai’s Icahn School of Medicine, described the reduction as substantial. She previously reported a 52% decline in sperm concentration among Western men over about four decades due to environmental factors and chemical exposures.
Swan emphasized the need for further research on neonicotinoids’ reproductive effects on both genders and their impact on couples facing infertility challenges.
The researchers concluded that additional studies are necessary to understand how neonicotinoid exposure affects semen quality over time and its implications for reproductive health.
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