Programmed to Be Fat?

Endocrine-disrupting chemicals could be predisposing humans to obesity – and their work may begin while we’re still in the womb.

There’s no denying that folks in the developed world are growing heavier. In this CBC The Nature of Things episode, originally screened on August 2, 2012, David Suzuki says babies have been getting larger since 1950. Today about half of all adults in the West are overweight, while one in six is obese. Even in Norway, a country known for its healthy lifestyle, 46 per cent of men and women are bigger than they should be. What’s happening here?

It’s easy to blame the epidemic on poor diet and lack of exercise, which certainly play a part. But scientists now believe another factor is at work: a group of environmental chemicals called “obesogens.” The term was coined by Felix Grun and Bruce Blumberg at UC Irvine to describe a group of endocrine-disruptors that change the way human bodies react to calories. Obesogens could be predisposing humans to a life of fatness – and their work may begin while we’re still in the womb.

Perhaps the most worrisome are Bisphenol A (which is allowed in food cans despite being labeled ‘toxic’ by the Canadian government) and nicotine (which can be conveyed to a fetus if its mother smokes). BPA has been linked to cancers and birth defects. Ninety percent of North Americans have BPA in their blood, and even small quantities are problematic because endocrine-disruptors have a counter-intuitive property: tiny doses can be more harmful than larger ones.

The current approach is to give new chemicals minimal testing and assume they’re safe if they pass.

Other obesogens include dioxins (which can be present in breast milk and fish) and the pesticide tributyltin (which protects ships’ hulls from barnacles). This is especially troubling in Canada because federal regulations addressing pesticide residues on produce are far less health-protective than they are in other countries.

Programmed to be Fat? (available to watch online) suggests greater application of the precautionary principle, under which chemical companies would need to prove products’ safety before they went to market. That sounds like an obvious step, but as Irvine professor of Developmental and Cell Biology Bruce Blumberg makes clear, it’s not widely applied. Blumberg says the current approach is to give new chemicals some “minimal toxicological testing” and assume they’re safe if they pass. He suggests the public would be well served by the reverse: an assumption of harm unless the opposite can be shown definitively. I like the program’s endorsement of the precautionary principle but wish its producers explored how to lobby for adoption. It would be wonderful if science documentaries explored problems and then helped to build social movements capable of addressing them.  

The program’s advice, such as it is, focuses mostly on pregnant women: eat carefully and minimize toxic exposures. No one disagrees with this but there’s a suggestion that tackling obesogens is fundamentally a job for the individual. That can’t be fair. We also need government to create a world in which mum doesn’t face chemical hazards in the first place.

Programmed to Be Fat?, Bruce Mohun (director), Vancouver: Dreamfilm, 2012, 45 minutes.

Reviewer Information

Gideon Forman is a long time peace and environmental activist.