For years, scientists have warned that male sperm counts are dropping around the world, but critics — chemical companies included — have questioned the data. But now, the largest, most rigorous study to date shows sperm counts are down by nearly 59.3 percent in North America, Europe, New Zealand and Australia, while sperm concentration has dropped by 52 percent overall over almost 40 years. This time, even many skeptics may be convinced.
The meta-analysis, which was published in the journal Human Reproduction Update, compared 185 studies, which included 42,935 male participants who offered their sperm between 1973 and 2011. And while South America, Asia, and Africa didn’t show declines in this report, that was likely because there wasn’t much data from those areas during the study’s time period. New research has come out of those regions since that suggests a similar decline in sperm, says Dr. Dr. Shanna Swan, lead author of the report and professor of Environmental Medicine & Public Health at Mt. Sinai Hospital in New York.
The report didn’t investigate the cause of the decline, largely because it’s extremely difficult to trace a reproductive problem back to a single toxin, given how many chemicals humans encounter on a daily basis. But Swan told FERN’s Ag Insider that farm chemicals and phthalates — chemicals that commonly leach into food through plastic — are major contributors to the problem. They include endocrine disruptors, capable of impeding testosterone and androgen, which is responsible for the development of male reproductive organs while a baby is in utero. Smoking (especially by a pregnant mother), obesity, and lack of exercise also hurt sperm.
“We’ve known for a long time that food was a major source of exposure to phthalates,” says Swan. “Eating unprocessed foods and not cooking in plastic or storing foods in plastic, keeping your foods away from plastic as much as possible will reduce your exposure.” But phthalates are also ubiquitous.
They show up in upholstered furniture and wall coverings, plastic water bottles, can liners (especially in the form of Bisphenol-A, aka BPA), and in the plastic-based machinery used to process food. A recent study paid for by environmental advocacy groups, including the Center for Science in the Public Interest, the Environmental Working Group, and the Natural Resources Defense Council, found widespread phthalate contamination in cheese. Milk is run through phthalate-heavy tubing and the chemicals bond easily to fat. Of the 30 cheeses tested all contained some level of phthalates, with the highest occurring in Kraft Mac & Cheese.
In 2014, a U.S. Product Safety Commission report urged the FDA to reconsider the safety of phthalates, citing their connection to poor semen quality, testicular cancer, and hypospadias — a range of developmental conditions including undescended testicles. However, most phthalates are still approved by the FDA.
As for farm chemicals, in 2002, Swan published one of the few studies conducted in a farming community focused on sperm count after discovering that the men of Boone County, Mo. — largely devoted to farming — had a 42 percent lower sperm count than their peers in urban Minneapolis.
Of the Boone men, those exposed to high levels of the herbicide alachlor were 30 times more likely to have poor sperm quality, while men with high levels of the herbicide atrazine (the second most commonly used herbicide in the U.S.) and the insecticide diazanon were 11.3 and 16.7 times more likely to have diminished sperm quality, respectively. Likewise, a 2013 meta-analysis of 17 studies found that 15 showed significant associations between exposure to pesticides and semen quality indicators (such as concentration, motility and morphology).
And yet, the hormonal effects of chemical exposure on farmworkers or other adults can often be reversed. Farmworkers can stop using a certain pesticide, for example, and their sperm will likely return to normal after a few months. Adults can stop microwaving leftovers in plastic and phthalates will eventually leave their body.
But developmental changes that happen in utero are permanent, says Swan. They can also impact more than the one generation, since the unborn infant is developing reproductive cells of their own, potentially passing on any glitches in the hormonal system to their own children. And the risks of impaired sperm or lowered sperm count go beyond fertility.
“Men who have lower sperm count or men who are infertile go on to die earlier,” says Swan, citing higher rates of cardiovascular disease, diabetes, and testicular cancer. Whatever is harming sperm is also damaging the hormones protecting a man’s health.
Yet, the toxins in our environment are invisible. Manufacturers don’t have to prove that the phthalates in their products are safe, and pesticide residues routinely show up on supermarket produce. In a world of chemicals, Swan warns consumers, especially pregnant women, to stay away from processed foods, because of the high phthalate count, and encourages them to eat organic foods to lower their “body burden” of pesticides.