How Could Dust Cause Obesity?

Well, this won't make neat-freaks feel any better. According to a new study released by Duke University, a certain receptor that's been linked to obesity in the human body might be activated by chemicals present in something pretty common: household dust. But the science is still too unclear to start manically hiring cleaners and throwing dust bunnies out the window in a panic. Calm down, put down the mop, and let's go on a journey through fat, chemicals, and bizarre human genetics.

We've known that obesity, while it's often caused by over-eating and under-exercising, can also have underlying physical causes. Some medications that cause weight gain, thyroid problems, and metabolic dysfunctions are a definite possible source, and there may be signs that some obesity could be genetic (though it's very early days for those studies). A potential mutation in a gene called KSR2, leading to excessive appetite and slow metabolism, has been linked to obesity in mice, and appears in a small fraction of obese humans. But this isn't the first time that environmental factors, like exposure to chemicals or pharmaceuticals, have been linked to the uptick in obesity worldwide. This study's just nabbed headlines because, hey, fat or thin, we all have dust under our beds.

So how the hell could normal household clutter cause obesity, and why are scientists urging caution? Let's take a look.

What Is The Obesity Receptor?

Let's talk about what dust is apparently "activating" in our bodies, first. The thing the Duke University study focuses on is a spectacular mouthful called peroxisome proliferator-activated nuclear receptor gamma. To save massive headaches and too much typing, it's shortened to PRARgamma.

PRARgamma is a kind of nuclear receptor sitting within your body's cells, which in plain English means that they're basically responsible for reading the levels of different chemicals in your body, like hormones and steroids. (They're a bit like weather stations.) Once the receptors get these readings, they make changes in response to them, adjusting your metabolism, internal temperature, and even your genes.

So PRARgamma is a powerful little beast. And it's been linked to obesity before: back in 1996, it was pointed out that PRARgamma actually sends messages directly to the genes that control our fat levels. And one 2007 study showed that the PRARgamma's control (or lack of control) of bodily inflammation was an important factor in developing obesity. Not only is the weather station tuned in, what it decides can have a huge effect on weight.

But the important thing, for researchers, is that this receptor can be activated to go to "action stations" by many things, including stuff introduced from the outside of the body. And that's where dust bunnies may prove to be a bit of a problem.

How Could Dust Cause Obesity?

The researchers weren't exactly looking at dust itself. They were looking at common chemical compounds that normally turn up in our grey undusted corners and under our beds. Where do they come from? Fire retardants, organophosphates found in a lot of insecticides, and polybrominated biphenyl ethers, which pop up in huge hosts of building materials, furnishings, electronics, and other common household stuff.

Considering that we ingest dust every day, purely through being in our houses, these things definitely enter our bodies. But what do they do while they're there? The Duke scientists picked out 30, and looked at what they all did to PPARgamma when they popped up in human cells, and the results were very interesting indeed.

Twenty-eight of the 30 were "weak or moderate" agonists, which means that they had small or medium potential to turn the receptor on — and start the body building up fat. By any standard that's a pretty spectacular result — and likely going to freak out anybody who's a) petrified of dust b) petrified of getting obese c) hates the idea of common chemicals in their body creating weird, unhealthy havoc. So, I don't know, most of us.

And when the scientists actually tested real dust samples from various human environments like gyms, they found that more than 50 percent of them had "significant" PPARgamma activation. Whee. Gyms: actually making you fat?

Why You Shouldn't Buy A $400 Vacuum Cleaner Just Yet

The scientists behind the Duke study make it clear that just because the 28 nasties can turn on the PPARgamma receptor doesn't mean that they do. They're not successful every time, or even most of the time.

And just because the PPARgamma receptor has been activated may not mean that obesity is definitely on the way. There are many factors that are currently under high scientific scrutiny for being possible obesity "triggers". Aside from the KSR2 gene, there's the leptid gene, which if mutated also leads to obesity. Scientists also continue to argue over whether obese genes always mean an obese destiny, or whether you can fight it. So "obesogens," as the chemicals that could mess up our metabolism are called, may not even be the dominant factor in the world's rising weight.

Cleaning out your closet may not be the most effective way to treat obesity, either: A new study released at the end of July claimed researchers may have found a molecule that "tricks" the body into losing weight by making it believe it's run out of energy. It basically causes the build-up of a particular molecule, called ZMP, in cells, which panics the body into upping its glucose intake and metabolism — which is exactly what happens when we exercise. It's exercise in a pill, and obviously is making a lot of people very excited.

Overall, though, it looks like we're increasingly needing to adjust our ideas of obesity, from just a too-many-calories-ingested thing to a complex condition caused by environmental, genetic, and childhood factors. And, either way, you should probably dust your house anyway. (Just wear a mask while you do it.)

Images: Brittanie Loren Pendleton, Anne Worner, Kim Carpenter, Garland Cannon/Flickr