BOB GARFIELD: This year Big Brother Mexico was also very successful raking in heaps of viewers and ad dollars. Like its blockbuster cousins from Africa to Europe, the show featured housemates who gossiped, fought, got naked and showered together. But in Mexico they also recycled and conserved water and made compost. From Mexico City, reporter Peter Aronson brought up the dirt. [SOUND OF CRUSHING PLASTIC BOTTLES UNDER FEET]

PETER ARONSON: Stomping on plastic soda bottles and then putting them into a recycling bin is a new idea for many people watching Mexico's version of Big Brother. Tatiana Rodriguez, a tall, striking 22 year old, [SOUND TRACK BIG BROTHER HOUSEMATES UNDER] spent 92 days in the Big Brother house developing new habits. [TATIANA SPEAKING IN SPANISH]

INTERPRETER: We separated cardboard, glass -- everything for the compost that we used in our garden. We had to brush our teeth with just a little tiny glass of water. We tried to avoid creating garbage. We used less soap for washing our clothes. Basically, everything was separating garbage and conserving water.

PETER ARONSON: Well-- not quite everything. The show isn't really about the environment. I mean on this day, one guy is washing dishes without running the water, but a woman is kissing another guy's feet! Here's executive producer Pedro Torres. [PEDRO TORRES SPEAKING IN SPANISH]

INTERPRETER: Well, as you know, Big Brother is a reality show which basically consists of 12 strangers who decide voluntarily to live together on television and in which there is only one winner. Over the course of 120 days, the participants complete various tasks.

PETER ARONSON: Many of them, including recycling, are made-for-tv tasks -- part of a publicity effort quietly engineered between executive producer Torres and the woman in charge of environmental education and public awareness in Mexico, Tiahoga Ruge.

TIAHOGA RUGE: I met Pedro at a social gathering, and I was telling him that I was really sad that Big Brother didn't really have a content and that, you know, being in my job I was always desperate to get messages out on the media on environmental issues, because the media is the strongest influence we have nowadays --especially a program like Big Brother which gets -- has a huge rating -- I don't know -it's between 70 and 80 percent of the population ends up watching some part of Big Brother!

PETER ARONSON: The show's producers claim an audience size of 10 to 15 million viewers a week, and the government wanted to show that audience how to do things like limit showers to only 5 minutes and keep water use under 24 gallons a day per person; how to run a blender on solar power and how to separate garbage into seven parts. They're on message now, because at the beginning of the season, the government brought in a personal ecological trainer to work with each of the residents. [MAN SPEAKING IN SPANISH] The man who was in charge of composting when he was on the show is 43 year old Alejandro Soliz, a car window repairman with short bleached hair, bright red pants and white leather shoes. [ALEJANDRO SOLIZ SPEAKING IN SPANISH]

INTERPRETER: I had already heard about the environment, and I had heard about how to save water, but I had no idea about separating garbage -- the biodegradable and organic stuff -- and that you can recycle and then make new things from recyclable garbage. And we wanted to make people aware that they can do this in their homes too.

PETER ARONSON: Starting next year, a new federal law will require Mexicans to separate their own trash into, at the very least, organic and inorganic material -- just like on the show. But some are skeptical about the idea of using Big Brother, and even soap operas, to put out the government's message. Francisco Peredo, a professor of communications at Mexico's National University, takes a dim view of the government's involvement in this show. He's working on a book about reality TV and has blasted Big Brother for encouraging violence and catering to the basest instincts. [FRANCISCO PEREDO SPEAKING IN SPANISH]

INTERPRETER: It seems to me that when Big Brother or other programs do this, they're doing it with the aim of justifying some kind of positive value that the programs want to appear to have. But I believe this type of program doesn't have any truly positive purpose. I think when they turn to methods like these, it only demonstrates a huge lack of imagination and a huge lack of responsibility.

PETER ARONSON: Just as the government is using the show, the show is also using the environmental theme to enhance its image. [CLIP FROM AD FOR BIG BROTHER MEXICO IN SPANISH] That translates as: Environmental Big Brother -- Saving the Planet. Executive Producer Pedro Torres. [PEDRO TORRES SPEAKING IN SPANISH]

INTERPRETER: Really, Big Brother had no need to be more popular or more loved by having an environmental element to it. We're doing it out of conviction. [AMBIENT STREET SOUNDS, PEDDLAR SHOUTING WARES]

PETER ARONSON: On bustling Moneda Street in downtown Mexico City, four young Big Brother fans ages 15 and 16 say they've noticed the environmental theme. [GIRLS SPEAKING IN SPANISH] But is that why they watch the show? [GIRLS LAUGHING -- NO!] Nah. It's because one of them likes Tony. [GIRLS GIGGLING] And that's just fine with the Ministry of the Environment!

TIAHOGA RUGE: If you don't make it fun, no one is going to watch it! And if you have some other elements in there like who is falling in love with whom, well, that's all right! It doesn't matter.

PETER ARONSON: For On the Media I'm Peter Aronson. [MEXICAN ORCHESTRA AND SINGERS]

BOB GARFIELD: Coming up, a new study shows liberals are boring and the silliest part of the news.

BROOKE GLADSTONE: This is On the Media from NPR.