Key words: condom, virus penetration, laboratory test, standards, tech support
A mentorship student from Thomas Jefferson High School for Science and Technology, Alexandria, VA, followed up on previous laboratory experiments that had demonstrated that viral passage under pressure through small, artificially-induced holes in latex condoms ceased almost completely within minutes upon commencement of testing. Three explanatory hypotheses were put forward: hydration might cause the latex to swell, thereby shrinking the hole; loose particles could block the hole; or the restrainer used to limit condom expansion under pressure might cause blockage of the hole. Experiments which measured the passage of virus under pressure through artificial, laser-drilled holes as a function of time were performed, using a low-pressure condom test apparatus without a restrainer. The initial rate of viral passage exhibited the theoretically-predicted fourth power dependence on hole radius. However, within a few minutes viral flow ceased. Microscopic examination of the holes before (dry condom) and after (wet) the experiment indicated that the holes did not shrink. Particles (donning powder, etc.) were found inside condoms that were large enough to clog holes. The kinetics of viral passage were consistent with sudden, complete closure of the holes. Thus, these data suggest that hole blockage be considered the primary cause of cessation of viral passage through small holes during laboratory experiments with these latex condoms. Further, it is unlikely that such hole blockage would be relevant in real-life use of condoms, with rare, naturally-occurring small holes.