In 2005, perchlorate was found to contaminate drinking water in 26 states, according to the EPA. (Photo courtesy of STI/NASA)
A new study from the Centers for Disease Control suggests that long term exposure to low levels of the chemical perchlorate may be hazardous to health, especially to women of childbearing age and children. Host Steve Curwood speaks with Dr. Richard Jackson, a former director at the CDC and professor of environmental health sciences at UC Berkeley.
CURWOOD: From the Jennifer and Ted Stanley Studios in Somerville, Massachusetts - this is an encore edition of Living on Earth. I’m Steve Curwood. A major study by the U.S. Centers for Disease Control has concluded that trace amounts of the rocket fuel perchlorate found in drinking water, milk and produce, may be endangering the health of millions of women and their children with thyroid disease.
The CDC study, begun in 2001, looked at nearly 3,000 Americans and found health effects at “exposure levels unanticipated” by previous research. The findings are sure to fuel an ongoing controversy among regulators about safe levels of exposure to perchlorate, a persistent pollutant which is found in the groundwater of more than two dozen states. To find out more, we turn now to pediatrician Richard Jackson, professor of Public Health at UC Berkeley, who is a past director of the CDC’s Environmental Health Unit.
JACKSON: Hi Steve, it’s a pleasure to be with you.
CURWOOD: So doctor how surprised were you by these results?
JACKSON: I was surprised. I really did not think we would find in a population that such low levels were having measurable impacts on people’s health. I was always taught that the higher levels have the impact. This is kind of a gold standard study. You have the best laboratory in the world for doing biomonitoring looking at a robust sample of the American people and coming up with findings that have been peer reviewed extensively and I think will hold up to scrutiny anywhere.
CURWOOD: Now, Dr. Jackson, first tell me why are women the risk group here and not men? What’s different about women’s body composition that makes them a vulnerable population to something like this?
JACKSON: Well you know we all need iodine in our diet. But women in particular because of pregnancy needs and others, need some more. In fact they need to be taking vitamins when they’re pregnant. Iodine is important as an adult. It helps you make thyroid hormone. Your energy levels are related to it. But it’s particularly important to infants to the fetus for its development. In fact if a baby is born without enough iodine or thyroid hormone on board they can be left permanently damaged. So it’s really this reproductive age that we are most worried about.
CURWOOD: Now what’s the connection between perchlorate and iodine and thyroid problems in humans?
JACKSON: Well, we’ve known for a long time that we can use perchlorate to treat people with hyperactive thyroids and it will suppress thyroid’s putting out of hormones. What we didn’t know is would low doses of perchlorate suppress the thyroid’s functioning. And it looks at least from this study, and it’s just one study that, particularly in women with low iodine levels, it is having an effect on the thyroid.
CURWOOD: So how many women have relatively low iodine levels or thyroid problems?
JACKSON: We guess that about a third of the population of women ought to be getting more iodine in their diets. In fact we’ve been noticing one of the reason CDC does these studies is actually in the beginning is to profile the nutritional level of people in the United States. Over the last 30 years iodine levels in the US population have been dropping.
CURWOOD: You’re a physician, a pediatrician, for somebody who’s listening who’s concerned, particularly a women of reproductive age who’s concerned about this, what precautions might she take.
JACKSON: I think one as a public health doctor, I’m pretty passionate that tap water ought to be safe and everyone ought to be able to drink it. You shouldn’t have to go to bottled water and other sources. So demanding that your water suppliers are providing water within the standards and demanding the standards come into compliance with up to date science is important, number one. Number two it is important to get enough iodine in our diets. About half a teaspoon of iodized salt a day will give you enough to get by just fine. Thirdly, women who are pregnant need to be taking their vitamins for folic acid and lots of other and calcium and lots of other reasons as well. So those would be three things I would do.
CURWOOD: How does perchlorate end up in our ground water supply? Who’s responsible?
JACKSON: Much of the perchlorate that’s in water is a byproduct of various industrial processes. It’s quite a durable molecule. It stays in the water for long periods of time and it actually can get in to food products if that water is used for irrigation. So we’re finding perchlorate in many food products, lettuce and other vegetables that are irrigated with this water as well as finding it in the water its self.
CURWOOD: Now there’s been quite a bit of controversy over the acceptable groundwater levels of perchlorate. What do you think the impact of the CDC study on perchlorate will be?
JACKSON: One: it shows the importance of biomonitoring. When I was learning toxicology we were told well the very low doses don’t matter. It’s really the large doses that create the poisonous effect. What we’re learning from these biomonitoring studies, where large numbers of people are examined for very small levels of these chemicals and then look to see the interaction with genes or other exposures and the rest. We’re learning really kind of surprising information. I was surprised that they found such a robust finding in the CDC study at this level. As the academy of sciences sits down and weighs all this information I suspect they’re going to, if all this holds up in subsequent studies, they’re going to recommend a more stringent level. But the bottom line is it needs to be an open scientific process up front and an open management process that’s understandable once we go into setting an actual standard.
CURWOOD: Dr. Richard Jackson is a professor of environmental health sciences and the former director of the Center for Disease Control’s National Center for Environmental Health. Thank you so much Dr. Jackson.
JACKSON: My pleasure Steve, thank you.
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