07 August 2007

Barriers to Best Practice

Just when I least expected it, I received a real stumper of a literature search request. A client from Public Health was looking for any recent research – actually anything at all on the effectiveness of plastic wrap (a.k.a. shrink wrap, Saran Wrap) as a safe barrier for oral sex. That should be easy, I thought, an interesting little side trip through the web, visiting some well-known safer sex sites and gleaning any references on offer. Not one to shrink from a challenge, I plunged right in.

Little did I know what I was getting into: there is more to wrap than sandwiches. The web contains multitudes of safer sex sites, most of them offering opinions on the use of plastic wrap. Where advice is given it covers the range from squeamish acceptance to lukewarm approval. But not one of these sites offers evidence in support of its opinion. Not even the CDC.

Unrolling the Secret of Polyethylene

Disappointed, I initiated a formal literature search. I began, as usual, with PubMed. It offered very little, although I did discover the unfamiliar MeSH headings Rubber Dams, Cellophane, Permeability, Polyethylenes, and Polyvinyl Chloride. Most of what literature I could find on safe sex barriers is about latex. Some articles on non-latex barriers, which looked promising initially, were actually about the shelf life or resistance to tearing of the material, or its permeability to semen, not about its ability to withstand microbial penetration.

Google Scholar, as usual, was a mess, with everything from a goofy patent for a safe-sex mask to a study of oral gratification in Melville’s Typee. As I anticipated, just-plain-Google was able to produce, amidst the unavoidable prodigality of its porn links, reams of consumer health literature. Much of this had not been updated in years. Here is a representative sample:

  • HIVInsite calls it "probably the most versatile barrier." No mention of the least versatile.
  • Gay Men’s Health Crisis says that it stops HIV and advises: "Be careful not to turn the dam or plastic wrap inside-out while you use it."
  • Some sites, such as the lgbthealthchannel, warn that ordinary plastic wrap can be used as a dental dam "as long as it is not the microwavable kind, which is porous." The question of which is which is left to the reader.
  • Even more cautious is the 2006 Oral Sex pamphlet from the Canadian Public Health Association, which does not even mention plastic wrap, only dams. Did they check the literature and decide that the evidence simply wasn’t there?
  • The men’s safe sex tips from Toronto’s Hassle Free Clinic also omit any mention of plastic wrap.

In none of the resources I found is there any evidence cited for the efficacy of plastic wrap in preventing the transmission of STIs. This is not purely an academic exercise. In a poster prepared by the Project START Study Group, Sexual behavior and substance use during incarceration (2004), we learn that 12% of incarcerated men in the United States are using Saran wrap and other plastic substances as a means of protection during consensual sex. Among lesbians and bisexual women, 2% report using plastic wrap for oral sex, according to a 2000 article in the Journal of the Gay and Lesbian Medical Association. What are heterosexuals doing? What about HIV-discordant couples?

I’m still looking for the evidence, and I have extended my search to other resources like Scopus and Web of Science. I have come across considerable research (and controversy) about the effectiveness of latex condoms, dams, and gloves, and polyurethane barriers such as female condoms. But the case for wrap is not transparent.

Safer Saran Wrap

The always surprising Wikipedia has articles on plastic wrap in general, and Saran in particular. It turns out this stuff is not the homogeneous thing I thought it was. Plastic wrap, known as cling film in Britain and cling wrap in Australia, was discovered by accident in 1953. In Canada, Saran Wrap is the genericized trademark. The original Saran Wrap was made of polyvinylidene chloride (PVdC). In 2004 the formulation was changed to low density polyethylene (LDPE). The manufacturer claimed that this change was a result of an initiative to look for more sustainable and environmentally acceptable plastic. The film in Saran Premium Wrap does not contain chlorine, which is a good thing. However, we are told that LDPE does not possess the same barrier qualities to oxygen, aroma, and flavour molecules as vinylidene chloride copolymers, making the new formulation a lower quality plastic wrap, less useful in protecting from spoilage or flavour loss. How would it deal with HIV or treponema pallidum pallidum?

I went to the official Saran website, http://saranbrands.com/. The manufacturer, SC Johnson & Son, calls itself a "family company." They have an online survey: "How do you use Saran products?" Wouldn’t they like to know. In the FAQ I discovered that Saran Wrap is microwaveable. I guess that would disqualify it from use in oral sex according to some so-called authorities. Beyond this, the website provides no assistance for the would-be barrier user. But believe me, the next time I’m putting away leftovers I won’t look at my roll of plastic wrap the same way ever again.

Plastic Wrap as Sex Accessory

To wrap up this discussion, there appears to be little scientific evidence for the safety of products like Saran or other plastic wraps when employed as barriers for oral sex. This is somewhat disturbing, given the near universal recommendation of plastic wrap by officials of the state as well as community activists for safer sex in the absence of preferred latex barriers like condoms or dental dams. In short, their reasoning is full of holes. Is this negligence or an excessively tolerant clinging to street-smart tradition? Could we also be dealing here with a coy, possibly sex-phobic reluctance to investigate the issue? Are we tempted to resort to lame humour in order to hide our embarrassment? Klingon safe sex: no bladed weapons!

There are other reasons for the lack of reliable information on plastic wrap. For one thing, this kind of research is unlikely to further any scientist’s career. Don’t expect generous government grants or a chirrupy announcement from the Bill and Melinda Gates Foundation. Another possibility, I suppose, is that either through innocence or denial this research topic has simply not yet occurred to anyone. Or is that stretching credibility till it snaps?

All I can say is that the next curious patron who comes to the library with this question will not find a barrier in me.

Selected, unsatisfactory references:

1. What's in store for non-latex barrier methods. Contracept Technol Update. 1998 Mar;19(3):40-1.

2. Carey RF, Lytle CD, Cyr WH. Implications of laboratory tests of condom integrity. Sex Transm Dis. 1999 Apr;26(4):216-20.

3. Cornish K, Lytle CD. Viral impermeability of hypoallergenic, low protein, guayule latex films. J Biomed Mater Res. 1999 Dec 5;47(3):434-7.

4. Drew WL, Blair M, Miner RC, Conant M. Evaluation of the virus permeability of a new condom form women. Sex Transm. Dis. 1990 17(2):110-2.

5. Free MJ, Srisamang V, Vail J, Mercer D, Kotz R, Marlowe DE. Latex rubber condoms: Predicting and extending shelf life. Contraception. 1996 Apr;53(4):221-9.

6. Frezieres RG, Walsh TL, Nelson AL, Clark VA, Coulson AH. Evaluation of the efficacy of a polyurethane condom: Results from a randomized, controlled clinical trial. Fam Plann Perspect. 1999;31(2):81-7.

7. Gallieni M. Transparent film dressings for intravascular catheter exit-site. J Vasc Access. 2004;5(2):69-75.

8. Imran D, Sassoon E, Lewis D. Protection of dressings and wounds by cling film [22]. Plast Reconstr Surg. 2004;113(3):1093-4.

9. Klein RC, Party E, Gershey EL. Virus penetration of examination gloves. BioTechniques. 1990 Aug;9(2):196-9.

10. Korniewicz DM. Effectiveness of glove barriers used in clinical settings. Medsurg Nurs. 1992 Sep;1(1):29-32.

11. Korniewicz DM, El-Masri M, Broyles JM, Martin CD, O'connell KP. Performance of latex and nonlatex medical examination gloves during simulated use. Am J Infect Control. 2002 Apr;30(2):133-8.

12. Korniewicz DM, Kirwin M, Cresci K, Sing T, Choo TE, Wool M, et al. Barrier protection with examination gloves: Double versus single. Am J Infect Control. 1994 Feb;22(1):12-5.

13. Lytle CD, Routson LB, Cyr WH. A simple method to test condoms for penetration by viruses. Appl Environ Microbiol. 1992 Sep;58(9):3180-2.

14. Lytle CD, Routson LB, Seaborn GB, Dixon LG, Bushar HF, Cyr WH. An in vitro evaluation of condoms as barriers to a small virus. Sex Transm Dis. 1997 Mar;24(3):161-4.

15. Macaluso M, Blackwell R, Jamieson DJ, Kulczycki A, Chen MP, Akers R, et al. Efficacy of the male latex condom and of the female polyurethane condom as barriers to semen during intercourse: A randomized clinical trial. Am J Epidemiol. 2007 Jul 1;166(1):88-96.

16. O'Grady NP, Alexander M, Dellinger EP, Gerberding JL, Heard SO, Maki DG, et al. Guidelines for the prevention of intravascular catheter-related infections. centers for disease control and prevention. MMWR Recomm Rep. 2002;51(RR-10):1-29.

17. Rego A, Roley L. In-use barrier integrity of gloves: Latex and nitrile superior to vinyl. Am J Infect Control. 1999 Oct;27(5):405-10.

18. Wiwanitkit V. Bloodborne viral pathogens and the feasibility of passing thorough the gloves: An appraisal and implication on infection control. Am J Infect Control. 2006 Aug;34(6):400.

19. Yip E. Consideration of barrier protection and latex protein allergy in the evaluation of medical gloves. J Infus Nurs. 2004 Jul-Aug;27(4):227-31.


Mary C said...

Mark - that certainly was an intriguing literature search to perform. The mention of plastic wrap being used for oral sex, as you have mentioned, is not found in the literature when doing a PubMed search. But I did find just one - which maybe you already have seen. It is PMID 11365487. It actually mentions plastic wrap being used as a substitute for dental dams.

Mark Rabnett said...

Hello Mary,
Yes, I did see that article. It is not a research article from a refereed journal, unfortunately. So it couldn't be cited authoritatively. That is why I ignored it. It's in the same category as the material I gleaned from various websites.

I see an article of this kind as an example of how street-smart information has been uncritically accepted by community-based organizations like the Test Positive Aware Network in Chicago. That's not to say the information is worthless. Common sense tells us that using plastic wrap for oral sex is better than nothing. But exactly how is it better? Where is the scientific evidence, based on a repeatable research results?

Thanks for your comment.


dysamoria said...

Excellent posting. i have cited this in an email to the author of an article recommending using plastic wrap as a safe sex barrier.

Unknown said...

Thanks Mark - this is really a helpful review!!