So I tried to get access to this paper when everyone ELSE had access to the press release, because I totally wanted it, but Sci doesn’t get press releases (I did try to get press releases, but one publishing group cited what I feel is a totally justified potential conflict of interest due to Sci being a scientist who needs to publish in said journal, which I understand. The OTHER publishing group told me they don’t like “anonymity”. It’s PSEUDONYMITY, not ANONYMITY, and I don’t need you anyway. And I find that to be a somewhat kneejerk and reactionary position from people who clearly neither know nor care about what potential the science blogsphere has. Humph.), and the paper itself wasn’t available by the time all the press coverage hit.

BUT NOW. NOW SCI HAS THE PAPER. And I’m gonna blog it. Because it’s both good and bad. Good for the guys with laptops to know. And bad for the people who attempt to sit next to those guys on the subway.

Sheynkin et al. “Protection from scrotal hyperthermia in laptop computer users” Fertility and Sterility, 2010.

I clearly need to find a way to put “scrotal hyperthermia” to use commonly in my daily speech.

So, as men may know (and as women may know), there’s a reason men’s balls hang low. The reason is that sperm do their best at a temperature that is slightly lower than normal body temperature (2-4 degrees Celsius lower, which means if your normal body temp is 37, your scrote is best at 33, and for Fahrenheit, if you’re best at 98.6, your testes are besties at around 93). This means that the testicles hang lower and outside the body cavity, in an effort to keep it slightly cooler, and this ALSO means that testicles respond, sometimes quite visibly, to changes in exterior temperature, in an effort to keep their temperature constant.

You get the idea.

Anyway, one thing that balls can’t respond so well to is HEAT. In response to cold, testicles get ever closer to the body cavity, but in response to heat, there’s only so low they can go. If the testicular temperature rises more than a few degrees, sperm don’t do so great. And there are some worries that this might impact potential fertility in men with hotter (and I presume sweatier) balls. Now, in normal, every day life, men may not have exposure to excess heat like this very often. But life ain’t so normal anymore. After all, what about this?

(Sci might be writing on one of these RIGHT NOW. Luckily, I have no testicles to be worrying about.)

Because of the massive increase in laptops, iPads, etc, etc, the scientists in this study decided to look at what effects laptop use might have on temperature of the testicles. After all, lots of guys are using lots of laptops, for lots of time these days. And high scrotal temperatures could have a rough effect on the fertility of those guys.

So they took 29 male volunteers of fertile age (21-35), and gave them laptops. They had them work on the laptops (I assume they worked, they may also have watched a movie or something, with their legs either close together (to balance the laptop), with a laptop pad (which you can buy), or with their legs 70 degrees apart, and with a laptop pad.

They then measured their scrotal temperature. They hooked up two thermocouples to the UNSHAVED anterior scrotum to measure temperature during the test. I really want to know if those things were sticky and the poor guys got an unintended waxing. And the scientists looked at scrotal temperature, the temperature reached, and how long it took.

Let’s take a look at the data.

You can see that all scrotes averaged out at the same basal temperature (where the lines meet at the left of the graph). However, you start getting some differences once the laptop computers are applied. All the users showed significant increased in nut temperature, with left nut and right nut experiencing similar increases in all conditions.

(Hopefully that will fit…)

But you can also see that significant differences in ball temperature were obtained in the different conditions. The highest, and the FASTEST increase in temperature was with the men sitting with their knees close together to support the laptop, without a laptop pad. They had an average increase of 2.4 degrees or so, and achieved a one degree elevation in only 11 minutes (well, the right scrote 11 minutes, left 12, dang lefty always lagging behind). With a laptop pad present, the time for a one degree increasse increased to an average of 14 minutes, but there was still a temperature increase of 2 degrees (nice job, laptop pad). BUT, with the laptop pad AND the knees spread 70 degrees to give proper testicular aeration, the total increase ended up at only 1.4 degress, and a one degree increase took almost half an hour.

The authors conclude that laptop use with close legs, even with a laptop pad, results in scrotal hyperthermia, and that you gotta keep those legs spread to keep the jewels cool.

While this study makes for some great media fodder and is of course either intentionally or unintentionally hilarious, there are a couple of issues that Sci noticed. First, where’s the condition WITHOUT the laptop? Will a guy with closely closed legs have an increase in scrotal temperature anyway? After all, one of the causes of “increased scrotal temperature” is actually sedentary lifestyle. And while they have the 70 degree leg spread condition with the laptop pad…what about without it? With the laptop presumably balanced on one knee? And while they used two different brands of Pentium 4, there are a LOT of other laptops out there, and some heat up a LOT more than others (for example, netbooks, which Sci knows from experience can practically burn your legs if left on too long). Why didn’t they try those?

And here’s another thing. Sure they assessed testicular temperature (lucky boys). And the temperature was higher. But they did NOT assess fertility. How many sperm made it? What were they like? None of this was assessed, and there is as yet no idea of how MUCH laptop exposure would be necessary to actually decrease your fertility. Maybe 30 minutes is ok, but 4 hours is not? What about acute laptop use vs chronic? So while it may be a good idea to be giving your testicles a little extra aeration during laptop use (or to use a table!), we aren’t talking huge decreases in yuppie fertility yet.

Sheynkin Y, Welliver R, Winer A, Hajimirzaee F, Ahn H, & Lee K (2010). Protection from scrotal hyperthermia in laptop computer users. Fertility and sterility PMID: 21055743