The dangers of phthalates (an ingredient in some plastics) as an endocrine disruptor are well-known. Now we discover, via a study conducted by Mt. Sinai Hospital, that they may in fact play a role in the childhood obesity epidemic. Ezra Klein however is unimpressed:
Thirty years ago, kids might have been sedentary and eating lots of crappy food, but they were eating less of it than they are now. Same for adults. According to CDC data, between 1971 and 2000, obesity in the United States shot from 14.9% to 30.1%. The main reason is simple enough: Average calorie consumption increased. Men went from 2,450 calories to 2,618 calories. Over the course of a year, that's an increase in 61,320 calories. The trends were even more striking for women: an average intake of 1,542 calories became 1,877 calories. That's 122,275 extra calories per year. (The gender difference here surprises me, incidentally.) Another study, this one from the USDA, estimated that "average daily calorie consumption in 2000 was 12 percent, or roughly 300 calories, above the 1985 level." This, they estimated, was the prime factor behind America's soaring rates of obesity and Type 2 diabetes.But Mrs. Beyond Green, a political scientist who studies public health issues, thinks Ezra is too quick to dismiss the potential role of phthalates. She points out that:
It may seem like calories in-calories out is the obvious, clear answer. But I think we actually don't understand the hormonal regulation of metabolic functions all that well, and so it seems PLAUSIBLE that the obvious answer may actually be wrong. It may be that eating a lot more calories makes us fatter, but that absent any other disruptions to the metabolic system, most people would eventually adjust to the new calorie load without becoming morbidly obese -- just a little bit fat. Enter phthalates (and whatever other junk is out there). It disrupts something in the metabolic balance and causes us to be unable to adjust to the new calorie load.One thing that's worth noting in the Mt. Sinai study is that we don't know the calorie intakes of those kids. It could be that high exposure to phthalates (and these kids had much higher than average levels of phthlataes present in their urine) causes obesity at caloric intake levels that might only be slightly above normal. Ezra does, of course, agree this should be studied further, but thinks the focus needs to remain on diet. At the same time, he also points out, dealing with the diabetes epidemic may be beyond the capacity of our (or any) health system:
[N]o one knows how you provide affordable medical services to a population where a solid quarter of the folks have type II diabetes. In fact, you probably can't do it. But that's where the trends are headed.Given the threat that diabetes represents to the system (not to mention to our health), it seems like even marginal contributors should be quickly addressed. Phthalates (along with their evil plasticizing brethren) may well have turned what might have been a manageable problem into an existential crisis.
Photo by Steve Wampler used under a CC license