This is actually a Friday Weird Science repost from the old blog. I’ve had a few requests to do something on condom breakage, though, in the words of Dr. Pal “I think a lot of the time when “the condom broke” they really mean it was in the dresser drawer.” It’s true, I’ve never actually heard of a condom busting WIDE OPEN in the middle of sexual intercourse. Condom slippage, I’ve heard of.
But condoms do break, the question is: why?
White, Hill, Bodemeier. “Male condoms that break in use do so mostly by a “blunt puncture” mechanism” Contraception 77,2008 360-365.
The best thing about this study by far? Showing it to the other people in the lab. I especially recommend showing the “coital simulator” around.
Unbelievable as it may be for a scientist, it seems that I need to get out more. The scientist larval stage, or “grad student” is rarely seen outside the labs, but last night I ventured outside my known territory in the company of a few other larvae. When not in the lab, the larval stage of the scientist doesn’t tend to move very far, stopping to rest and refuel at bars for long periods of time before continuing on.
One of my fellow grad students brought up something truly awesome last night: A study covered in Nature News on condom breakage.
Condom failure is a relatively rare phenomenon, about 0.4-2% for rubber condoms and 0.6-6% for synthetic, though the actual breakage number in a 1000 use study is usually less than 10. Of course, numbers are easy to obtain, what is hard to figure out is WHY the condoms are breaking. Is it lubrication? Is it strength? Is the user completely incompetent or naive? Broken condoms are not usually returned (it is fairly easy to imagine why) to the study centers, so it’s hard to study exactly why condoms are breaking, and so it’s hard to improve the condoms.
So this study analyzed 972 USED condoms that had been returned as consumer complaints, washed and disinfected them (Glad they disinfected, at least), and analyzed them for location of breakage and type of breakage that had occurred. They also conducted a survey to ask those who had not returned broken condoms why the condoms had broken. Finally, to evaluate WHY the condoms were breaking, they made this:
They refer to it as a “simple mechanical coital model”. Unfortunately they fail to give dimensions for the model, describing it only as “physiologically accurate”, but to me that thing looks like it’s over two feet long!!! At least it looks like that if it’s sitting on the floor and those are windows. But I think that’s an outlet over there, so I guess it’s roughly normal size.
So what did they find?
Of the condoms they received, 474 were actually broken, 203 had some other defect (they do not say what), and another 290 were not actually defective. Most of the condoms were broken in the “teat” area (the closed end), which is not surprising, as that is the part of the condom receiving the most mechanical stress. But some of the condoms showed breakage, not at the tip, but as a kind of eruption through the side wall.
A condom with ruptured tip.
They got about a 50% reply rate for the survey, finding that 97% of condoms had broken during intercourse, without any reports that “unusual or athletic practices were taking place” (heh, heh. I wonder what rate of condom breakage happens when things are especially ‘athletic’?). 92% on users reported that they did not use any other lubricant (some, like petroleum jelly or mineral oil, can weaker condoms).
Looking for possible mechanisms of breakage, the researchers repeated stretched condoms over a “condom demonstrator” (which is used in condom factories and looks like a large test tube). Repeated stretching did eventually cause breakage, and they noted that after several stretchings, the amount of force required to break a condom is actually fairly low.
They did notice that failures could be broken down into several types, though none appeared to be due to manufacture, and it is believed that “users are breaking normal…condoms because of the circumstances that arise during an individual act of intercourse”. Eruption punctures, those causing holes in the walls or tip during use, appear to be caused by the penis pushing through the intact wall, a process they called “blunt puncture”.
With the use of their coital model, they determined that breakage could be caused when the condom was stretched over the tip of the penis model (in other words, by not leaving a little reservoir of space at the end), with lots of lubrication inside, little lubrication outside, and a tight fit between artificial penis and artificial vagina. By classification of the returned condoms, they found that 90% of failures could be accounted for by “blunt puncture”.
So what does this mean? It means the pointy end of…you…goes in the pointy end of the condom. Not the side, not the wall of the condom. The pointy end. It also basically means that, to have condoms with ‘blunt puncture’, you basically have to be putting it on in an incompetent manner. It also implies, however, that repeated stretching can weaker the latex. So if you stretch it MORE than once, you might want to use another one.
Finally, any scientific study is good if you include a coital simulator. I can only imagine the grad student who got to make that thing from scratch. Should they ever meet Sci, they are getting a beer on me for being AWESOME.
WHITE, N., HILL, D., & BODEMEIER, S. (2008). Male condoms that break in use do so mostly by a “blunt puncture” mechanism☆ Contraception, 77 (5), 360-365 DOI: 10.1016/j.contraception.2008.01.014
Filed under: Friday Weird Science |