Arctic Gender Imbalance
Air Date: Week of September 21, 2007
(Courtesy of www.bigfoto.com)
Only girls are being born in a village in Greenland. Host Steve Curwood turns to Lars Otto Reiersen, of the Arctic Monitoring and Assessment Program, to find out what may be behind a growing gender imbalance in babies born around the Arctic Circle.
CURWOOD: From the Jennifer and Ted Stanley Studios in Somerville, Massachusetts - this is Living on Earth. I’m Steve Curwood. In certain villages in northern Greenland something is completely out of whack—only girls are being born. These reports from villages near the U.S. Air Force base in Thule are now being explored by scientists.
But studies conducted a few years ago now coming to light show that in other Arctic regions, the sex ratios of babies are also out of kilter. In 2004 the Arctic Monitoring and Assessment Program found a correlation between exposure to PCBs and shifts in the sex ratios of babies born to indigenous mothers living in the northern reaches of Russia. PCBs and other persistent organic chemicals such as pesticides travel from industrial countries up the food chain into the blubber of marine mammals.
Lars Otto Reiersen is the executive secretary for the Arctic Monitoring and Assessment Program. His group conducted the study as part of ongoing research on pollution, diet and health in the region.
REIERSEN: The most interesting and surprising result was that we saw a change in the sex ratio that we could correlate to the levels of PCB in the mother’s blood. And we saw that if the mother had more than four micrograms per liter in her blood the average was to change two girls per boy in the population that we studied. And that’s a quite dramatic change from a normal situation where there are more boys than girls born.
CURWOOD: Now when you say more boys than girls born, how many more boys than girls?
REIERSEN: I think normally—statistically—there is 1.05 or 1.1 boy per girl. That’s the normal average.
CURWOOD: In this population though it’s 2.0 girls per boy.
REIERSEN: Yeah, when the mothers have these levels of PCB, yeah. And we also saw that the birth came earlier and the weight on the newborn babies that had the highest levels were lower than the normal.
CURWOOD: Tell me about how you went about collecting your data. How did you find your subjects? Who were these people?
REIERSEN: Based on the study we’d done in Greenland and Canada we are focusing mainly on the indigenous people living off the marine food chain because we’ve seen that these people have the highest levels because of their lifestyle. And we worked together with the indigenous people to collect the samples over a year’s period to get enough statistical data. And we have continued after that. The first report was published in 2004 and the new data just confirmed what we saw earlier. So what we’re looking into now is to try to understand what is the mechanism behind it.
CURWOOD: Now, looking at your report here I’m just struck by the apparent effects that PCBs have on the sex ratio of children and the way it changes. The chart you have there, I’m looking at page 175. The chart that you have there shows that as you increase exposure to PCBs, at first you get way more boy babies than girl babies. But then as you go higher and you get above four micrograms per liter of blood you get way more girl babies.
REIERSEN: Yes, I can see that. And the scientists do not have any good explanation of why it looks like you have a stimulation at the lower levels and then you get the opposite effect when you go beyond that level. So, what we’re doing now is that we’re looking into the certain polar arctic to see—do we see any similar effects in Canada or Greenland?
CURWOOD: How might PCBs do this do you think?
REIERSEN: Well, it could be what we call the mimic of the hormones. That early in the pregnancy that some of these pesticides may mimic testosterone or estrogen. That’s documented from science. So, that might be what’s occurring but that’s too early to say for sure what’s the mechanism.
CURWOOD: Now, PCBs are concentrated in the arctic and concentrated in marine mammals. But what might this mean for the rest of us around the world who have exposure to PCBs but at a much lower level?
REIERSEN: That’s a good question. PCB is all over, it’s not only in the Arctic. You have it all over the world in the terrestrial and marine food chain, and in fresh water. So, from laboratory studies we know that PCBs may effect reproduction, may have effects on cancer and immune systems. But I think it’s very difficult to document that on the population level. You have to have very detailed studies like the one we did in Chukotka area.
CURWOOD: How have the governments of the Arctic responded to your research?
REIERSEN: Well, they have responded very active. I think you have got the Stockholm Convention in place to a far extent due to the work we have done in the Arctic over the years.
CURWOOD: And the Stockholm Convention is?
REIERSEN: That is an international agreement among countries to reduce the production and use and discharge of persistent organics. I think that is what you need actions to clean up the use of PCB and the old waste sites of PCB and others of these chemicals. That’s important actions to be taken.
CURWOOD: Lars Otto Reiersen is the executive secretary for the Arctic Monitoring and Assessment Program. Thank you so much, sir.
REIERSEN: Thank you.
CURWOOD: For a link to the Arctic pollution study, visit our website: L-O-E dot org.
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