Doctors question study claiming pesticides lower semen quality
The research, published in Human Reproduction, studied 155 men and found that among them, those who ate more than 1.5 servings of fruits and vegetables (with higher levels of pesticide residue) per day had 49% lower sperm count than men who ate less than half of the servings per day.
They also had 32% lower percentage of normal sperm and lower ejaculate volume, it said.
“Consuming organically-grown produce or avoiding produce known to have large amounts of residues, may be the way to go,” said Jorge Chavarro, assistant professor and the study’s senior author.
Lessons from well-conducted studies should be considered when advising men who are attempting to conceive, Dr Hagai Levine, who wrote a commentary on the study, added.
Junk science
However, health professionals are not convinced. They said that the “tantalising” results should be interpreted with caution.
Professor Allan Pacey at University of Sheffield said: “[The study] did not measure the pesticide residues in the actual food the men ate but rather inferred this from other data…we cannot discount that it is another aspect of the men’s diet or lifestyle that is actually the cause of the effects seen.”
He added that there was also no evidence at present that switching to organic fruit and vegetables could improve semen quality.
Professor Sheena Lewis at Queen’s University Belfast agreed that the results should be taken in context. She pointed out that the study included a relatively small number of men (155) who were undergoing infertility investigations. “So their semen may be more vulnerable to pesticide insult than the general population,” she said.
American Council on Health and Science Dr Gil Ross called the study an “agenda-driven junk science” while Dr Josh Bloom said that of these many errors it had, any one alone would have been sufficient to render the study “worthless”.
“[The study] serves to further confuse already bewildered consumers who are bombarded by conflicting information,” he said.
The study
The research had classified fruits and vegetables into high versus low-to-moderate pesticide residue groups based on data from the United States Department of Agriculture (USDA) Pesticide Data Program (PDP).
Fruits and vegetables with higher levels of pesticide residues included strawberries, spinach, and peppers while peas, beans, grapefruit, and onions were categorised as low-to-moderate, it said.
The researchers used data from men enrolled at a fertility centre in Boston from 2007–2012 with validated survey information about their diets.
The authors accounted for factors such as smoking and body mass index—both known to affect sperm quality—and looked for connections between the men’s intake of produce with pesticide residue and the quality of their sperm.
Given that pesticides are designed to kill and harm pests, it was not surprising that they could harm human reproduction, said Levine. “Male fertility studies provide an opportunity not only to better understand the causes of an important public health problem, but more broadly to illustrate effects of the modern environment on human health,” he added.
Source: Human Reproduction
Vol.0, No.0 pp. 1–10, 2015, doi: 10.1093/humrep/dev065
‘Fruit and vegetable intake and their pesticide residues in relation to semen quality among men from a fertility clinic’
Authors: Y.H. Chiu, et al
