Thirty
years of safer-sex advice were thrown into confusion at the 2010 International
Microbicides Conference when a survey of lubricant use amongst a group of women
and gay men found that those who used lubricants for anal sex were three times
more likely to acquire gonorrhoea, chlamydia or syphilis than those who used
none.1
HIV incidence was not measured as the group studied was too small for this to
be a meaningful datum.
The
effect was independent of the number of partners people had or how many times
they had sex, and was also independent of whether they used condoms or not.
Researcher
Pamina Gorbach of the University of California, Los
Angeles, stressed that these results came from a small
survey and that her study was not powered to analyse the risk of various
different lubricants.
However,
an accompanying study by Charlene Dezzutti and Janet Russo of the University of Pittsburgh did find that some lubricants
created more cellular damage than others.2
Gorbach’s
survey was part of the U19 rectal microbicide research initiative funded by the
US National Institutes of Health. Between October 2006 and December 2008, 879
men and women from the U19 programme completed computer-assisted
self-interviews for the researchers about their sexual behaviour and were
tested for rectal STIs – gonorrhoea, chlamydia and syphilis.
In
order to include enough women who had had anal sex, half the interview group
consisted of women who had had receptive anal intercourse (RAI) at least once
in the last year, whereas gay men were only included if they had had RAI in the
last month.
Just
under half of the people interviewed (421 people, 47.6%) reported having had
receptive anal sex within these criteria: 229 men having had it in the last
month and 192 women in the last year. Of these, 302 completed the behavioural
survey and all STI tests; the remaining data concern this group.
The
group was 58% male and was a somewhat older group than many sex surveys, with a
median age of about 40; 51% were African-American and the average socioeconomic
status was poor, with 21% of the group classing themselves as homeless and 35%
as disabled.
Three-quarters
of the group (230 people) said they had used a lubricant during the last time
they had had receptive anal intercourse. Lubricant use was less common in
African-Americans (38.5%) and Hispanic people (58%). More HIV-positive people
used a lubricant than HIV-negative people.
People
used various kinds of lubricant: 67% had used a water-based one such as KY
Jelly, 28% a silicone-based lubricant, 17% an oil-based substance such as Crisco, and 6% a numbing lubricant
designed to deaden sensation.
One
in 12 group members tested positive for a rectal STI (5.6% of women and 10.2%
of men); only chlamydia and gonorrhoea were included in the analysis as
syphilis is often transmitted orally.
Over
one in nine (11.7%) of lubricant users were positive for a rectal STI compared
with one in 22 (4.5%) who did not use lubricant: this was statistically
significant (p=<0.05).
More
than two-thirds (68%) of people diagnosed with rectal gonorrhoea and/or
chlamydia had used a lubricant compared with a third of people who had not used
a lube.
In
multivariate analysis, using a lubricant was associated with a more than
threefold greater risk of acquiring an STI (relative risk 3.15, 95% CI, 1.23 to
8.04). This was after controlling for number of partners, frequency of sex,
condom use, gender and HIV status. In other words, lubricant use was not a
surrogate marker for other risk behaviours but appeared to pose an independent
risk. When syphilis was included in the analysis, the association of STIs with
lubricant use was even stronger.
“What’s
our take home message here?” Gorbach was asked. She said that her message would
be that people should choose their lubricating substance carefully. Lubricants
were not regulated like medicines: they were classed as ‘medical devices’ and
did not have to undergo stringent safety testing. Many had ingredients that
were “not friendly” to the cells lining the rectum.
To
underline this, another study (Russo) tested for toxicity six lubricants that
can be bought over the counter in the USA. These were five water-based
lubricants (Astroglide, Elbow Grease, ID Glide, KY Jelly and PRÉ
vaginal lubricant) and one silicone-based one (Wet Platinum).
The
physical properties of each lubricant were measured. Four lubricants (Astroglide,
KY Jelly, ID Glide and Elbow Grease) were strongly hyperosmolar.
This means that they would cause water to diffuse out of the cells lining the
rectum into the rectum itself.
The
lubes were tested on ‘friendly’ bacteria that are part of the normal vaginal
flora. Astroglide killed off one species of Lactobacillus, and KY
Jelly, which contains the disinfectant clorhexidine, killed all species.
The
four hyperosmolar lubricants stripped off the epithelium (outer layer) of cells
from rectal tissue. In contrast, PRÉ and Wet Platinum caused
relatively little damage. Astroglide caused almost as much damage as
nonoxynol-9, the spermicide whose use has been shown to increase susceptibility
to HIV.
As
members of the audience commented, these studies do not imply that people
should be advised not to use lubricant in anal sex, as this can cause trauma in
itself. However, there is clearly an urgent need to conduct further research
into sexual lubes, distinguish between harmful and harmless ones, and probably
introduce more stringent safety checks for them before licensing them for
over-the-counter sale.