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ATLANTA — Pesticides used in our homes, gardens and lawns and sprayed on foods we eat are contributing to a dramatic decline in sperm count among men worldwide, according to a new analysis of studies over the last 50 years.
"Over the course of 50 years, sperm concentration has fallen about 50% around the world," said senior study author Melissa Perry, dean of the College of Public Health at George Mason University in Fairfax, Virginia.
"What is not known is the culprit," Perry said. "While there are likely many more contributing causes, our study demonstrates a strong association between two common insecticides — organophosphates and N-methyl carbamates — and the decline of sperm concentration."
Widely used pesticides
One of the most frequently used compounds in the world, organophosphates are the main components of nerve gas, herbicides, pesticides and insecticides and are also used to create plastics and solvents.
"They are widely used in agriculture on the crops we eat," Perry said. "We use them in structural applications within homes and buildings, apartment buildings, as well as for ornamental lawn upkeep. They're available for consumer purchase so organophosphate exposures have been demonstrated to be relatively widespread."
N-methyl carbamates are structurally and operationally similar to organophosphates, killing insects by damaging their brains and nervous systems. They are used to make insecticides that are applied to a "variety of field, fruit, and vegetable crops for control of beetles, borers, nematodes, weevils and similar pests," according to the U.S. Centers for Disease Control and Prevention.
"As we sort of start to close the net around factors that could negatively impact fertility, these pesticides start to rise to the top," said Dr. Alexander Pastuszak, an assistant professor of surgery and urology at The University of Utah School of Medicine in Salt Lake City. He was not involved in the new study.
"There's enough evidence to really start to say yes, these types of compounds can negatively affect fertility in men," he said. "Ultimately, you don't know the impact on actual fertility until and unless you start trying to get pregnant."
'A public health issue'
The study, published Wednesday in the journal Environmental Health Perspectives, examined studies around the world on the two chemicals and found 20 that met the study's standards for inclusion. Those studies looked at 42 different levels of impact among 1,774 men in 21 different study populations.
Men who were more highly exposed to the pesticides, such as those who work in agriculture, had significantly less sperm concentration than men who had the least exposure to organophosphates and N-methyl carbamates, the study found.
Sperm concentration is a measure of sperm per milliliter of semen, while sperm count is the millions of sperm in the entire ejaculate. Sperm count, along with the total number sperm swimming progressively in the semen, are the more important measures of future fertility, according to experts.
However, sperm concentration "is an important measure of sperm quality for comparing men across studies because it adjusts for variability in semen volume," Perry said.
Animal studies have shed light on how these pesticides may impact sperm, according to the study. They appear to directly interfere with sexual hormones, damage cells in the testes, and alter neurotransmitters in the brain that impact sperm production, the study said.
"Sperm is an incredibly sensitive endpoint when it comes to overall health for men," Perry said. "My best advice is to be aware of insecticides in one's environment and to recognize that avoiding unnecessary insecticide exposure is a good thing, especially if you're planning on a family and wanting to conceive children."
Exposure to pesticides in food is still a significant issue: An advocacy group recently gave major food manufacturers a collective F for their failure to lower the levels of pesticides in the foods they sell as promised.
"This really is a public health issue," Perry said. "We can take an individual approach, but it is on a population basis that people are being exposed to pesticides and other factors.
"Action to reduce insecticide exposure is needed, so that if men want to father children, they're going to be able to do so without being concerned about overall reductions in sperm concentration," she added.
What to do about sperm count
When it comes to pesticide exposure in food, however, there are actions consumers can take. Choosing organic foods is a surefire way to reduce pesticide exposure, experts say. While organic foods are not more nutritious, the majority have little to no pesticide residue, according to Alexis Temkin, a toxicologist at the Environmental Working Group, a research and advocacy nonprofit that focuses on consumer health, toxic chemicals and pollutants.
"If a person switches to an organic diet, the levels of pesticides in their urine rapidly decrease," she told CNN in a prior interview. "We see it time and time again."
If organic isn't available or too pricey, "I would definitely recommend peeling and washing thoroughly with water," Temkin said. "Steer away from detergents or other advertised items. Rinsing with water will reduce pesticide levels."
Additional tips on washing produce, provided by the U.S. Food and Drug Administration, include:
- Handwashing with warm water and soap for 20 seconds before and after preparing fresh produce;
- Rinsing produce before peeling, so dirt and bacteria aren't transferred from the knife onto the fruit or vegetables;
- Using a clean vegetable brush to scrub firm produce like apples and melons;
- Drying the produce with a clean cloth or paper towel to further reduce bacteria that may be present.
