In today’s Wall Street Journal, Allysia Finley warns that environmentalists and liberal leadership in Congress have another industry in its cross-hairs: the chemical industry. A new study attempts to make a connection between the prevalence of chemicals and rising rates of obesity.

Finley explains why this link seems dubious, or at least unproven by the evidence:

Antichemical crusaders argue that the rise in obesity has coincided with the increase in use of these chemicals-despite that fact that they’ve been widespread for over 50 years and obesity didn’t start surging until about 1980. They also point to some rodent and in vitro studies that suggest exposure to plastics during infancy and gestation can signal the body to turn precursor cells into fat cells, which may predispose people to pile on the pounds later in life.

But biologist Randy Seeley at the Endrocrinology Department of the University of Cincinnati College of Medicine is skeptical. He says the current data have “a lot of weaknesses” and that “the work has not been done very well.” After reviewing the studies, he performed a more rigorous experiment exposing female mice to low doses of BPA. While their pups were born bigger and grew faster at an early age, the effect faded over time such that as adults they were no fatter than the controls. Still, he says, it’s “very hard to prove something is safe” since there are countless doses and responses that could be tested. And studies on rodents can’t necessarily be extrapolated to humans.

Chemist Joe Schwarcz at McGill University’s Office for Science and Society notes that the doses of these chemicals found in food are likely too low-we’re talking in millionths of grams-to have a material effect. “Every day people are exposed to hundreds of thousands of natural and artificial chemicals which would show very similar effects if run through these sensitive tests,” he says. Even the sugar fructose, which naturally occurs in fruit, and genistein in soy show obesogenic effects when tested in rodents.

All of this helps explain why the National Toxicology Program reported in 2008 that “there is currently insufficient evidence to conclude that bisphenol A exposure during development predisposes laboratory animals to develop obesity or metabolic diseases such as diabetes, later in life.”

I wrote about attempts to demonize the use of chemicals in cosmetics years ago. And as Finley warns there are new efforts, both in the states and at the federal level, to ban the use of common chemicals in the name of protecting our health.

There are a number of issues that seem to need to be considered before making such a ban: what’s likely to replace the use of these chemicals? Will they be replaced with something that’s been evaluated or something that’s just less known? If the alternative is that everyone has to eat and use only “organic” goods, how much more are we going to be spending for food and household items? And since poverty is linked to obesity, what will the effects be on our health of making us all poorer? And if exposure to chemicals is to blame and these chemicals are everywhere, then why aren’t we all obese?

Perhaps there are outside forces that contribute to obesity. But has anyone done a study to see if there is a link between the rising obesity rate and an increase in calories and decrease in physical activities? I’m no scientist, but it seems to me that this most obvious answer is probably behind the bulk of the problem. Readers, if anyone knows of a study that shows that calorie intake hasn’t been rising in concert with our rising obesity rates, please pass it on.

Good health is important, and it makes sense to try to figure out why our country is having such a problem with weight gain.  Yet government intervention to ban a substance should be a last, not first, resort.