A Low Blow From The LaptopDec 9, 2004 | Globe and Mail New medical research is about to hit the technology industry below the belt a provocative U.S. study has concluded that the last place any male should use a laptop computer is in his lap.
Research published today in the journal Human Reproduction has found that laptops, combined with the thighs pressed-together posture needed to balance them, give off enough heat to raise the temperature inside testicles by nearly three degrees Celsius (5.4 F).
This increase, researchers warn, could endanger the production of healthy sperm and lead to infertility.
"Some people don't use laptops on their laps, but a lot of young men, or boys, have all these wireless services and they do use them on their laps to play games or do all sorts of things, on the sofa, or the school bus, or in the backyard and this is a continuous heat exposure. But in 10 or 20 years when they try to have a family they might have problems," said study leader Yefim Sheynkin, a urologist at the State University of New York at Stony Brook.
So where should men use a laptop? "Use it on a desk," he said, "anywhere but on the lap."
If the findings sound, well, nuts, no doctor is likely to dismiss them.
The health of sperm globally has been a subject of great concern for the past 12 years. Reports, particularly from Western countries, suggest that sperm counts and quality have been declining for half a century, while testicular-cancer rates are rising. The phenomenon remains controversial, but no one disputes that semen has its environmental enemies and heat is one of them.
Heat is known to mangle the traditional tadpole shape of sperm, as well as limit their numbers, stunt their growth and make them sluggish. Doctors strongly advise men having trouble in becoming fathers to abstain from hot baths, hot tubs, and sometimes saunas. Even serious scientists have compared the cooling benefits of boxer underwear over briefs.
"If [Dr. Sheynkin] can measure that difference in temperature [with laptop use], it is significant, but it needs more study," said male-infertility expert Victor Chow, a consultant with the University of British Columbia's Centre for Reproductive Health. "We need to know if it actually lowers sperm counts or [if] the only thing you can say about it is that laptops heat up testes."
But Christopher Wood, a 30-year-old consultant with Maverick Public Relations in Toronto and a laptop enthusiast, is already reconsidering his favourite weekend ritual.
Ever since his girlfriend bought a laptop five months ago, Mr. Wood has spent Sunday mornings snuggled in bed, leaning back with coffee in hand, watching DVD movies on the laptop, which is perched, naturally, on his lap.
"I never thought it could impact my ability to have children," Mr. Wood said. "I mean it would be really sad that I would not be able to have children because I decided to watch Shrek in bed."
Most people assume, he said, that the main risks of computer use are strained wrists or aching backs. But he admitted that the notion that a laptop's heat may be hazardous to his reproductive parts is not a complete surprise: The warmth the machine generates through his duvet and sheets on Sunday mornings is intolerable.
"I haven't been able to get through a whole movie yet," he said. "I don't think I'm doing myself any favours."
Dr. Sheynkin, SUNY's director of male infertility and microsurgery, conducted the study over two one-hour sessions with 29 healthy men aged 21 to 35. In one session, researchers recorded the temperature of the subjects' scrotums at three minute intervals as they sat with their thighs together as though they were using a laptop.
In the second session, on a different day in the same room, at the same time and ambient temperature, with the men wearing the clothes they had worn in the first session, the researchers took scrotal temperatures again. But this time, the men had a working laptop that heated up from 31 degrees to 40 degrees at the end of the one-hour experiment.
Sitting with their thighs together increased testicular temperature by 2.1 degrees. When the laptop was added, the temperature rose to a median 2.6 degrees in the left testicle and 2.8 degrees in the right. Several earlier studies have shown that increases of more than one degree can have a negative effect on sperm development and fertility.
"Testes usually hang down away from the body," Dr. Chow noted, generally maintaining a temperature of 11/2-degree cooler than the rest of the body.Dr. Sheynkin said sperm may take three to six months to recover from heat damage, since it takes the testes roughly 72 days to produce it. But chronic exposure, he said, may have long-term effects.
"We definitely need more studies," said Dr. Sheynkin, who pointed out that laptops now outsell desktop computers.
"If we disregard this now, this may lead to real problems in the future." There are no known studies of the effects of laptops on women's fertility.