Exposure to two types of pesticides used in the U.S. could result in reduced sperm concentration, according to a study published this week in the Environmental Health Perspectives journal.
“Although additional cohort studies can be beneficial to fill data gaps, the strength of evidence warrants reducing exposure to OP and NMC insecticides now to prevent continued male reproductive harm,” said the study.
OP refers to organophosphate insecticides. According to the U.S. Centers for Disease Control and Prevention, organophosphorus chemicals are used to kill many types of insects.
“These chemicals account for a large share of all insecticides used in the United States, including those used on food crops,” it said.
NMC stands for n-methyl carbamate insecticide. An example is methomyl, an “insecticide used to control foliage and soil-borne insect pests on a variety of food and feed crops, including field vegetables and orchard crops,” per the U.S. Environmental Protection Agency.
Previously, studies have found that both female and male fertility rates have been declining over recent decades, according to a 2021 article published by Scientific American.
“The whole spectrum of reproductive problems in males are increasing by about 1% per year in Western countries. This ‘1% effect’ includes the rates of declining sperm counts, decreasing testosterone levels and increasing rates of testicular cancer, as well as a rise in the prevalence of erectile dysfunction,” said the outlet. “On the female side of the equation, miscarriage rates are also increasing by about 1% per year in the U.S., and so is the rate of gestational surrogacy. Meanwhile, the total fertility rate worldwide has dropped by nearly 1% per year from 1960 to 2018.”
A 2017 study found that sperm counts dropped between 1973 and 2011, driven by a 50–60% decline among men unselected by fertility from North America, Europe, Australia and New Zealand.
“Because of the significant public health implications of these results, research on the causes of this continuing decline is urgently needed,” it said.
A 2019 article in the Biology of Reproduction journal said that “sperm counts worldwide have halved and sperm quality has declined alarmingly,” over the past 40 years, “with one in 20 men currently facing reduced fertility,” and one in six couples dealing with infertility issues. It said that potential causes for the decline in male fertility included environmental endocrine disrupting chemicals, rising rates of obesity, and the trend of delayed parenthood.
“Despite half of infertility cases involving male factors, men have been largely neglected in terms of research, diagnosis, and treatment. Diagnostic methods for male infertility are based on outdated semen assessment methods that have remained essentially unchanged for the past 50 years,” said the article. “It is time to promote a culture that puts as much emphasis on male as on female reproductive health. It is time to put the forgotten men center stage in preconception education and in the development of better methods to diagnose and treat infertility.”
Researchers who conducted the study on pesticides also said that meta-analyses of the impact of pesticides on sperm count are rare despite evidence of the chemicals’ negative impact on male fertility. They used three scientific databases to collect information about the link.
“The body of evidence was rated to be of moderate quality, with sufficient evidence of an association between higher adult OP and NMC insecticide exposure and lower sperm concentration,” said the study.