Not just little adults

If you’re a consumer of health and environmental news, you’ve almost certainly heard it said that “children are not just little adults.” The warning comes up a lot in the context of medical research, because children’s bodies metabolize some things differently than do adults. That’s particularly important because somewhere in the vicinity of 80 percent of drugs prescribed for children have never been adequately tested for pediatric use. Lacking viable alternatives, doctors have gotten in the habit of prescribing them off-label. But the lack of testing means that there’s a lot docs can’t know for sure – like, how effective and safe the drugs actually are, what the best dosage is, and more.

The warning comes up a lot in discussions of toxics, as well, because children are often more vulnerable to certain chemicals than adults – for most of the same reasons, and a few more. Their smaller bodies mean that the same level of exposure generally packs a bigger wallop. They metabolize some things differently. Their neurological systems are still developing and are therefore vulnerable to greater harm. And kids also have unique avenues of exposure – for example, many kids put their hands in their mouth a lot, and spend time playing in places where they can get toxics on their fingers. So, for example a child whose parent works on a farm might get a dose of pesticides that have been tracked into the house and deposited on a carpet where the child plays.

The latest entry in the “not just little adults” file is a study published by the National Institute of Environmental Health Sciences (full study here, and considerably more lay-reader-friendly abstract here). The study contrasts the blood levels of bisphenol A (BPA) in adults with those in children, relying on mathematical modeling to predict the levels. BPA is a plastic that’s widely used in food containers, and it has fallen into rapid disrepute over the last few years, because it is suspected of causing a variety of health problems. According to NRDC, “Research shows that everyday levels of BPA may be linked to reproductive abnormalities, prostate and breast cancer, neurological damage, insulin resistance and diabetes, obesity, and cardiovascular disease.” (NRDC petitioned the FDA to ban BPA’s use in food packaging this past October.) It’s currently used in plastic bottles (including baby bottles) and in linings of some metal food containers. Heat, as in the kind applied to the contents of a baby bottle, and acidity, as in the type typical of sodas or tomato-based products, can cause it to leach into food.

More than 90 percent of Americans have BPA in their bloodstream. So researchers Andrea N. Edginton and Len Ritter set out to determine how long BPA stayed in the bloodstream before being broken down by the body. What they found was that the bodies of children under 2 years old aren’t very well equipped to break the stuff down. A particular liver enzyme is required for the task, and babies don’t have nearly as much of it as adults do. As a result, the researchers’ modeling shows, babies have about 11 times as much BPA in their blood as adults do, rendering them far more vulnerable to its ill effects. Not just little adults, indeed.

So far, the Food and Drug Administration has been reluctant to move on the problem. Last September, it issued a statement saying it saw no need to restrict the use of BPA. But in October, a panel of experts slammed FDA’s conclusion, saying it lacked. "reasonable and scientific support." Just recently,  FDA said it wanted to gather more information on the subject before reaching a final conclusion.

Better than nothing, but only barely.