Researchers from a Canadian university say the women work in a dangerous and toxic environment, but the brewers maintain they're fulfilling their obligations.
Presenter: Robert Carmichael
Sharon Wilkinson, country head Care International; Professor Ian Lubek, author of report University of Guelph, Canada
CARMICHAEL: Going for an after-work beer with your friends is a long-established tradition in many parts of the world, and here in Cambodia it is no different.
Each evening groups of men routinely head to beer gardens like this one in Phnom Penh.
There is nothing flash about the place: Around me are plastic chairs, cheap tables, a concrete floor and jugs of beer. Above is a corrugated iron roof. This beer garden - like many - looks more like a large shed than a bar or pub.
The beer promotion women are easy to spot: They wear uniforms emblazoned with their brewer's logo and branding - such as Heineken, or Carlsberg, or one of the local beers. Their job is to promote their brand.
The position of Cambodia's 4,000 or so beer promotion women has long been of concern to health experts.
Sharon Wilkinson heads Care International, an NGO that has worked with beer promoters for six years. She says beer promoters have a low standing in Cambodian society.
SHARON WILKINSON: Women generally who are working in the entertainment industry in Cambodia - whether it's karaoke, massage parlours, in the beer promotion work - they are stigmatised by society. They are considered to be bad women, even while two-thirds of the women that we're working with are working women trying earn an income to feed their children.
CARMICHAEL: Researchers from Canada's University of Guelph (pronounced 'Gwelf') have studied beer promoters working in the town of Siem Reap in northwest Cambodia for a decade.
Lead researcher Professor Ian Lubek says more than half of the beer promoters interviewed last year sold sex. He says low monthly salaries of $81 dollars a month force them into sex work to make ends meet, and increase their risk of contracting HIV and other sexually-transmitted diseases.
IAN LUBEK:Most of these beer sellers are supporting about three almost four dependents each. We feel that it's an economically-driven activity. It's quite shameful to them - they lose respect in their home villages. They can't get married because they agree to sell sex. But they have no other way.
CARMICHAEL: Professor Lubek says the solution is for the world's biggest brewers to pay the women a living wage. He also wants them to provide anti-retrovirals, or ARVs, to those women who need them, and to improve training on HIV/AIDS and combating sexual harassment.
The Big Four global brewers in the report are Belgium's Anheuser-Busch InBev; London-based SAB-Miller; Dutch firm Heineken; and Danish brewer Carlsberg. Between them they sell one in every two beers globally. They have the lion's share of Cambodia's beer market too.
All four brewers claim wages are sufficient, and note that salaries are higher than the women would earn for more gruelling work in garment factories.
Carlsberg's press office, for instance, said that a survey commissioned by the local beer industry association found average monthly income was 110 dollars. And it said Carlsberg's 635 beer promoters are generally not the sole breadwinner.
But when asked to reveal how many of its beer promoters are single mothers - and who therefore would be earning less than the $200 a month a family needs - Carlsberg refused, on the grounds that to do so would be illegal in the United States.
Wages aside, the four brewers say they give training on sexual health, provide free transport to and from work, and ban the women drinking alcohol while they work. And they state that the women are employed by local distributors, not directly by the brewers, which limits their responsibility.
On the topic of HIV/AIDS, Professor Lubek sees a clear link between HIV risk and low wages. He says more than 80 of 900 beer promoters interviewed over the past seven years have died at an average age of just 25.
He suspects HIV-related infections are at least in part to blame, but says the lack of death certificates means the causes will never be known. The brewers strongly deny any link between HIV and low wages.
Care International found less than one-third of the beer promoters it interviewed in Phnom Penh had engaged in informal sex work - that's half the rate Professor Lubek found.
Sharon Wilkinson says the solution lies in changing the way in which beer promotion women are viewed.
SHARON WILKINSON: But if we're really going to make the change, we have to change the behaviour of the drinking man. That's where the change comes, and that's what we're working on.