A new study out of the Netherlands has found a link between prenatal exposure to PCBs and dioxins and alterations in gender differences of childhood play behavior. Host Steve Curwood talks with Nynke Weisglas-Kuperus, the lead researcher of the study.
CURWOOD: It’s Living on Earth. I’m Steve Curwood. There’s increasing concern that exposure to low levels of PCBs and dioxins is affecting the hormonal balance in both animals and people. Now, for the first time, a study has found a correlation between prenatal exposure to these chemicals and changes in the gender-linked play of young children.
While not everyone agrees what exactly constitutes gender-related play, the researchers say their findings involving more than 160 children are worth noting. Joining me now is Dr. Nynke Weisglas-Kuperus. Shes a developmental pediatrician at Erasmus University in Rotterdam. And she led this study, which was published in the journal Environmental Health Perspectives. Dr. Weisglas-Kuperus, welcome to Living on Earth.
CURWOOD: You began this study by collecting blood samples from mothers, and also blood from the umbilical cord. What did you find in those samples?
WEISGLAS-KUPERUS: We found in the samples that all mothers and children are exposed to these kind of chemicals.
CURWOOD: And then, about seven years later, as I understand it, you asked parents of the children you were following to fill out a questionnaire about their childs behavior. You looked at things such as how often a child plays with dolls or tool sets, or how often they get into rough- and-tumble play. And certain activities on the standardized test have been deemed more masculine, others more feminine. This type of questionnaire, of course, is not without controversy. But, what did you find?
WEISGLAS-KUPERUS: Well, we found that boys with higher PCB exposure were less likely to engage in masculine patterns of play, while girls with higher exposure were more likely to engage in masculine play.
CURWOOD: And what happened when you looked at dioxin exposure?
WEISGLAS-KUPERUS: With dioxin exposure, we found something different. More feminine behavior was found in both boys, and as well as girls. So, it was not sex-specific in dioxins.
CURWOOD: How do you explain these results?
WEISGLAS-KUPERUS: Well, I think, at the beginning, I have to say, we didnt expect these kind of results. We started this questionnaire because we thought, well, PCBs and dioxins are hormone disrupters, and then you expect less masculine play in boys, for example. But now, we found different things. And we think that it is because when you work with environmental levels, there are all kinds of actions. There are PCBs which are estrogenic. There are PCBs which are anti-estrogenic. There are PCBs which are androgenic. So, its a whole mixture of things. And that could mean that you find different things.
CURWOOD: What do levels of exposure mean here? In typical toxicology, you figure the more that somebodys exposed to a particular chemical, the bigger the impact. What happened in this case?
WEISGLAS-KUPERUS: I think that is very difficult to say because these are very subtle findings and very low levels. But, of course, what I think is important to mention and to realize that its not--we cannot establish a causality with the kind of studies we do. You work with a population in a certain country with an environmental mixtures of PCBs and dioxins. And yeah, you find what you find.
CURWOOD: How confident are you that you are looking at true gender differences in the behavior of these children? What about just differences in the home environment?
WEISGLAS-KUPERUS: Well, we corrected for a lot of things in this study. And when you read the article you could see that we measured things like home environment, social economic status, intelligence of the parents. So, we corrected for those kinds of factors.
CURWOOD: Now, you also found that there was no effect that you were able to measure on children who were breast-fed, even though breast milk contains a fair amount of PCBs and dioxin, versus those who are formula-fed with no measurable PCB or dioxin. How do you explain this?
WEISGLAS-KUPERUS: We think that in the womb the child is more vulnerable to those kind of effects than after birth.
WEISGLAS-KUPERUS: When the fetus is still young, the central nervous system is still developing.
CURWOOD: Some people use the term "window of vulnerability." Is that accurate?
WEISGLAS-KUPERUS: Yes, and I think the window of vulnerability for these kinds of things is prenatal and not post-natal.
CURWOOD: Parents listening to us right now might be--well, they might become quite concerned about what their children are being exposed to. Whats the message you want to convey here?
WEISGLAS-KUPERUS: Well, I think, the first message is that what we did is an exploratory study. And we found subtle differences in play behavior. So, its subtle differences in the normal range of play behavior. I think thats very important to realize for parents. And you should realize that we measured play behavior at a certain age. And that, in my opinion, we dont suggest that it should have something to do with childhood gender non-conformity later on. I mean, its very subtle, we found.
CURWOOD: Nynke Weisglas-Kuperus is a developmental pediatrician at Erasmus University in Rotterdam, the Netherlands. Thanks for taking this time with me today.
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