Pesticides on Vegetables and Fruit Linked to Lower Sperm Counts

High-pesticide fruits and vegetables may lower sperm count. Victor Ruiz Garcia / REUTERS

Fruit and vegetables are good for you, but the pesticide residues that can linger upon them carry a number of health risks. For the first time, scientists have shown that men who eat produce with a lot of chemical residues may be less fertile.

A study published in the journal Human Reproduction found that those who consume fruits and vegetables that are known to have the highest quantity of pesticides have sperm counts that are 50 percent lower than those who eat the smallest amount of these items. Those who ate the most high-pesticides fruits also had 32 percent more abnormally shaped sperm, says Dr. Jorge Chavarro, an epidemiologist at the Harvard School of Public Health and one of the authors of the study.

The fruits and vegetables that carry the highest levels of pesticides includes apples, strawberries, celery and spinach, according to the Environmental Working Group, a nonprofit consumer health organization. Those with the lowest levels of residues include avocados, sweet corn and pineapples.

The study looked at data from questionnaires and sperm count measurements from 155 men enrolled in the Environment and Reproductive Health (EARTH) study, a continuing research effort in Boston funded by the National Institute of Environmental Health Sciences. Although this isn't a huge sample of people, the difference in sperm count between the groups was quite large, and thus compelling, Chavarro says.

"The paper makes a convincing case that dietary exposure to pesticides can adversely impact semen quality," write researchers Hagai Levine and Shanna Swan, who weren't involved in the study, in a commentary in Human Reproduction. "While this finding will need to be replicated in other settings and populations, it carries important public health implications," add Levine and Swan, who are at Hebrew University in Jerusalem and the Icahn School of Medicine at Mount Sinai Hospital in New York, respectively.

Specifically, it may make sense for men who are already worried about low sperm count to avoid certain high-pesticide fruits and vegetables, suggests Chavarro, who takes a "better safe than sorry approach." Chavarro says he was skeptical that he would see any effect of pesticide residue on sperm counts, but his mind was changed by this new data.

Previous research has shown that farmworkers exposed to high levels of pesticides have lower sperm counts, so it's not necessarily surprising pesticide residues could be having this effect, says Niels Skakkebaek, an expert on fertility at the University of Copenhagen, who wasn't involved in the paper.

It's not known exactly how pesticides may impair male fertility. But there are a number of possible explanations. Most important, many of these chemicals are endocrine disruptors, substances that interfere with the hormonal system, the study notes. Hormones are involved in hundreds, if not thousands, of cellular processes that ultimately lead to sperm production. They are also easily disrupted, which can cause problems down the chain of cellular processes. Secondly, some animal studies have some that various pesticides can cause an increase in rates of apoptosis, or programmed cell death, in the gonads, leading to fewer sperm being produced.

Pesticides have "been constructed to kill living organisms that we want to get rid of," Skakkebaek says. "Therefore, they may also interact with sensitive human cells like the germ cells," which produce eggs and sperm, he says.

"We know that semen quality is very poor among young men today and testicular cancer incidence is increasing," he adds. "Although we know that environmental factors are to blame for some of these trends, we do not know the specific causes. We certainly need more information about the safety of modern pesticides. Therefore, I believe that studies like this one are important."