TORONTO - We hear occasional reports of declining sperm counts in certain parts of the world, warnings that fish downstream of major pollution sites have reproductive abnormalities and most recently, that the chemical bisphenol A may be linked to fertility problems in animal studies.
So if a guy has in mind that he wants to start a family some day, should he be concerned? Or, as the saying goes, might he be wondering if his "boys can swim.''
While many things are beyond any individual man's control, experts do have some advice about what to avoid and what might be helpful as men attempt to put to use what is an astonishing natural resource.
"Men produce about 100 million sperm a day, every day, basically 1,000 sperm for every heartbeat. From puberty until death,'' says Bernard Robaire, a professor in the departments of pharmacology and therapeutics, and obstetrics and gynecology, at McGill University in Montreal.
Robaire has been interested in the effects of chemicals -- mainly anti-cancer drugs -- on male reproduction for 30 years.
"If you look at any drug that affects cell division, so all of the anti-cancer drugs, for example, all of those will affect spermatogenesis, the making of new sperm, and will affect both the quantity and the quality of the sperm you make.''
Certain environmental exposures -- including heavy metals, organic solvents and some pesticides such as DDT -- have been a focus of attention as well.
"We know that auto mechanics, painters, have a higher incidence of abnormal progeny, have a higher rate of infertility, have a longer time to pregnancy,'' Robaire says.
"We haven't necessarily narrowed down what is the one chemical -- there probably isn't one chemical. It probably is a mix of solvents and greases and whatever else they're exposed to that's affecting them.''
But by far, it's exposure to the toxins in cigarette smoke that fertility experts are unequivocal about -- men who are trying to have babies should avoid smoking.
"Cigarette smoking does have an effect on the quality of sperm, motility of sperm and the DNA of the sperm,'' says Dr. Keith Jarvi, director of the Murray Koffler Urologic Wellness Centre at Mount Sinai Hospital in Toronto.
"So you can damage the DNA by smoking. If you stop smoking, it seems to improve.''
Whether or not a man's mother smoked could be a factor as well.
Robaire and Jarvi both note that studies found lower sperm counts in men in Denmark over a 40-year-period starting in the 1940s, while the numbers remained stable in nearby Finland.
The researchers saw that men who had lower sperm counts in Denmark had mothers who were smokers, but in the last 20 years the sperm counts there have been rising again, Robaire says.
And for men who toke rather than smoke, Jarvi warns that marijuana is also bad for sperm quality.
Alcohol can be a problem as well.
"If you are having trouble conceiving, then alcohol consumption is also something that you'd want to watch,'' says Warren Foster, director of the reproductive biology division, and a professor in department of obstetrics and gynecology at McMaster University in Hamilton.
There's some evidence that a glass of red wine may act as an antioxidant, which in theory might improve sperm quality, Jarvi notes. "However, if you use more alcohol or excessive alcohol or enough to damage the liver, then you're going to cause an effect on sperm production.''
Robaire says a lot of alcohol can inhibit the making of testosterone, produced along with sperm in the testes.
"The sperm have grown to depend on having very high levels of testosterone in order to be made,'' he explains. "If you decrease testosterone production in the (sperm) factory ... then the consequence is that you will be making less sperm. So most alcoholics have low sperm production.''
Many people have heard the warnings about tight underwear and pants, but it's still something Jarvi discusses with patients.
"The `Saturday Night Fever' look is definitely not good for the sperm count,'' he says with a laugh, recounting some of the "slightly bizarre'' research to back that up.
"There's one study that came out where they put fairly snug underwear on men and all the men became azospermic, which means they have no sperm at ejaculation after a couple months.''
It's a heat issue, Jarvi says, adding that saunas or hot baths aren't a good idea either.
"We have a few people who are in flight suits, and they had quite a bit of heat in the groin region, and so we think that's related to it (difficulty conceiving). Workplace exposures -- people on the line, chefs who are on the line. They have heat exposure because their testicles are around the same height as the preparation area.''
But sperm often improves once the men spend time away from the heat, he says.
There was a theoretical study looking at the temperature of laptop computers -- again, a possible heat issue -- but Jarvi says he doesn't know if they could be implicated in infertility.
And Robaire is fairly dismissive of preliminary research in the journal Fertility and Sterility from the Cleveland Clinic that found an association between patients' cellphone use and their sperm quality.
"It was not impressive,'' he says of the data, adding more research is needed.
Still, Jarvi says he would position his cellphone, which he wears on his belt, away from his testicles. "I actually, about two years ago, changed to wearing it on my hip, so it was about 20 centimetres, 25 centimetres away.''
In terms of food intake, Jarvi points to a "really good study'' recently that found men who had more folic acid in their diets had a reduced chance of sperm DNA abnormalities. Folic acid is found in leafy green vegetables, citrus fruit and enriched breads and pasta.
"Right now, we have enough evidence for the infertile men to say that folic acid might be beneficial and (it's) very unlikely to hurt you by taking a supplement.''
Diane Allen, executive director of the Infertility Network, says a diagnosis of infertility is really difficult for men because they typically don't have the support networks or talk about their feelings as women do.
"A lot more needs to be done about male infertility,'' she says. "Certainly people who are struggling with infertility need to get treatment. But also at the same time, we need to get our focus on looking at prevention.''
Foster says those worried about chemicals in the environment might want to reduce fat intake because any of these compounds primarily would be stored in the fat component of meat and fast foods. "Anything deep fried you want to avoid.''
Aim for a well balanced diet, he says.
As for bisphenol A, which can leach from polycarbonate bottles, especially when heated, Robaire says some animal studies suggest it can mimic estrogen and act on hormone receptors. "It can cause growth of the prostate and it can cause a decrease in spermatogenesis (sperm production).''
There are differing findings on whether enough is absorbed from the plastic to have an effect, he says.
"The same men who are going to be worrying about the polycarbonate are going to be riding a bicycle, and are going to have more damage on the testes from the saddle of the bicycle than anything they could take from the bottle they would be using.''
"Or they're going to be wearing tight underwear. So it's a question of understanding what the level of risk is. And the risk is very low because the doses are very low.''
