Study Links Fetal Bisphenol A Exposure to Behavioral Problems in Girls

By Douglas Main | October 26, 2011 1:06 pm

A study published this week in the journal Pediatrics found a link between levels of bisphenol-A in pregnant moms and behavioral problems such as anxiety and hyperactivity in their daughters at age 3. No such effects were seen in boys. BPA has estrogen-like activity and can lead to developmental and behavioral problems in animals—but whether or not it does the same in humans, and at what dosages, is a subject of considerable debate. This study won’t settle the debate but highlights the need to answer some basic questions about BPA that remain surprisingly unclear.

What’s the Context:

  • Bisphenol-A is used in many types of plastics like polycarbonate, linings of metal cans, and in receipts (even some labeled “BPA-free”). It shows up in the urine of the vast majority of Americans.
  • Since BPA mimics estrogen in the body, it may effect mental and sexual development, especially if it is present very early in life. For this reason it has been explicitly banned from being used in baby bottles in several European countries, and BPA manufacturers say they don’t sell the chemical to makers of baby bottles.
  • Animal studies show fetal or early-life exposure to the chemical can interfere with mental development and behavior, like hyperactivity and impaired sociality.

How the Heck:

  • 244 pregnant women from Cincinnati, Ohio, had levels of BPA in the urine tested at weeks 16 and 26 of pregnancy, and again within 24 hours of giving birth. BPA levels were also tested in the urine of their children at ages 1, 2, and 3.
  • Behavioral problems were measured by two surveys filled out by parents when the children were 3 years old. The tests sought to identify problems in executive function, depression, anxiety, and attentional deficits.
  • Levels of BPA in the children were not linked to behavioral problems. However, the average level of BPA found in the urine at weeks 16 and 26 did appear related to behavioral issues in the girls (but not boys), namely increased levels of depression, anxiety, and hyperactivity.
  • Researchers don’t know why BPA may impact girls more than boys. They speculate that it may disrupt early neural processes that give rise to behavioral differences between males and females, like aggression and anxiety.

Not So Fast:

  • Critics of this study rightly point out that BPA is quickly metabolized in the body; a 2002 study found its half-life to be about 6 hours. However, a more recent study found that BPA may be metabolized more slowly and that there are significant non-food sources of the contaminant.
  • Another study found that people who ate food with high levels of BPA showed very low levels of it in their blood.
  • It remains unclear exactly how much BPA is absorbed into the bloodstream and how BPA may accumulate in fat stores within the body.
  • Given this uncertainty, measuring urine levels of BPA only twice during pregnancy may not be a good indicator of a fetus’ total BPA exposure. It would be better to measure blood levels of the chemical more often and earlier in the pregnancy.

The Future Holds:

  • Despite the uncertainties in this study, it may make sense for pregnant women to try to limit BPA exposure during pregnancy, especially early on—this can be done by avoiding packaged foods and eating fresh fruits and vegetables, etc.—which is healthy anyway.
  • The FDA says it’s still “looking into” the health effects of BPA, although it remains legal in almost all food containers.
  • There’s enough evidence to curtail our use of BPA, at least in products aimed at pregnant women and infants. This is, of course, easier said than done, considering how cheap, useful, and ubiquitous the chemical is.

Reference: Joe M. Braun, Amy E. Kalkbrenner, Antonia M. Calafat, Kimberly Yolton, Xiaoyun Ye, Kim N. Dietrich, Bruce P. Lanphear. Impact of Early Life Bisphenol A Exposure on Behavior and Executive Function in Children. Pediatrics, Published online Oct. 24, 2011. DOI: 10.1542/peds.2011-1335

Image: katerha / Flickr

  • Katharine

    If BPA mimics estrogen and causes these behavioral problems, one supposes that women with sufficiently high levels of estrogen in their bloodstream would also have daughters with behavioral problems.

  • Josephine

    I remain of the conviction that many “behavioural problems” are more due to parenting than pre-natal chemical exposure of whatever kind. The correlation may simply be that people who eat canned food in significant amounts make poorer parents.

  • Mike Empyema

    American women are behavioral monstrosities. Do a BPA study in the Philippines, Russia, China, the Middle East… or Utah, or Crown Heights, Brooklyn.

  • Geack

    @ Katherine – Exactly what I was thinking. If we’re worried that BPA mimics estrogen, that assumes that elevated “estrogen-like” activity in pregnant mothers is a problem. So someone should try to correlate estrogen levels and child behavior before we can assume BPA is an issue.

    I also can’t place much faith in any study relying entirely on parents’ consistency in evaluating the behavior of three-year-olds – especially in such a small sample. Different people have pretty wildly varying interpretations of the same behavior in their kids – it would be difficult to design a questionnaire that eliminated this subjectivity. This article is a case where it would be VERY useful for the author to provide some info on the strength of the reported correlation. I know they linked to the study, but not all of us have the statistics background to interpret the raw data.

  • Catherine

    @Mike Empyema: What makes you think that? Is beceacause we American women dress how we want & don’t stare at the ground every time a man walks by, mingle freely or do you just watch Snookie or Jerry Springer & think we all must act that way. What yr were you born in, 1855? I really hope you don’t live in the USA, have American kids or you don’t have a free spirited American Wife! Anyway I wonder if the reseachers took into account cultural notions as to how a little girl should act vs a little boy. No I don’t remember every day from birth, but I remember being raised differently from my brother 2 yrs older than me. If he made a bodily noise it’s funny! If I did that I’m not being a little lady! (I was told ladies only make bodily noises in the bathroom!) If he ran around like a nut on a rainy day, aww, he’s pent up! I did that: sit still like a lady! Never mind that little kids just donot care about our preconceived notions & have the same levels of energy. I don’t suggest we start referring to kids as its or raise them gender netural but cut the girls some slack! I’m lucky I didn’t buy into my familys beliefs & didn’t end up a an uptight prude who can’t think for herself or not run around like a nut on a rainy day!

  • Jay Fox

    @1 &4: I think that the problem with estrogen mimics is that while they bind to estrogen receptors, they do not function as estrogen. So every receptor with a plugged in mimic does NOT do what it is supposed to do. This would seem to compare to a woman with LOW amounts of estrogen.

  • Tom Andersen

    Looks wrong. With 244 subjects, thats about 120 girls. Then the study only finds that women with higher BPA at weeks 16 and 26 had bad behaving girls. How many women is this based on?

    Ok – downloaded the study. It looks like by the same reckoning, that BPA ingestion actually CURES behaviour in boys! (look at Figure 2 A vs B). The real answer is had by ignoring a girl vs boy division, in which case the study shows exactly nothing, which is all you could expect from an n = 244. In any case the random dots on the graphs are obviously not anything to draw a conclusion from.

    If girls vs boys did not bring out a signal, the ‘researchers’ could have used any of the other factors they recorded, like race, income, education, etc.

    Studies like this need to get in the news, so that the people who did the test can get more money to do more work. The sad state of science funding means that sensationalism is a great way to get funded.

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