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Public Radio's Environmental News Magazine (follow us on Google News)

Chemicals and Health

Air Date: Week of

Perchloroethylene is one chemical used in dry cleaning. (Photo: Flickr Creative Commons, Telstar Logistics)

There are tens of thousands of chemicals in everyday products. Only a fraction of these have been tested for toxicity and health effects in the U.S. Host Bruce Gellerman talks to Richard Denison, a senior scientist at the Environmental Defense Fund, about news studies that raise troubling health questions.


GELLERMAN: It's Living on Earth. I'm Bruce Gellerman.

It’s taken nearly a quarter of a century but the EPA has finally concluded that the chemical perchloroethylene is a likely human carcinogen. You know Perc., at least by the smell. It’s used by many dry cleaners; but now the EPA says it will largely phase out the cancer-causing solvent.

Perc. is just one of more than 62 thousand industrial chemicals that were presumed safe back in 1976. That's when the federal government first began regulating these compounds. But still today, most have never been investigated for health effects, they were grandfathered in.

Now three new studies suggest some of these chemicals, even measured in parts per billion, can have far reaching health effects, and Dr. Richard Denison of the Environmental Defense Fund says there's no avoiding them.

DENISON: The amounts are really staggering and they've grown dramatically over the last few decades. One estimate puts it at 27 trillion pounds per year in the U.S. That's the equivalent of 250 pounds per person every day.

GELLERMAN: Well, in your recent blog you write about three recent studies that raise concerns about some of these chemicals. Let's go through these studies, okay?

DENISON: Sure. They are among a group of studies that are looking directly at effects in people. Most of the data we've relied on in the past has been data derived from laboratory animal studies. But increasingly the field of epidemiology is finding that linkages directly to people can be established between chemical exposures and certain types of health effects. And these are three studies that do just that.

GELLERMAN: The first one has to do with something called PCE, or I guess some people know it as Perc. It's used as a solvent in dry cleaning, degreasing, spot removers, that kind of thing, right?

DENISON: That's right. It's also got a lot of industrial uses for cleaning metal parts and so forth.

GELLERMAN: The study that you cite was done recently by Boston University researchers.

DENISON: They looked at a large group of people, some 800 people that had reported some level of exposure to this chemical, either while they were in the womb, in other words, their mother was exposed, or in their early childhood. And this was the result of contamination of drinking water in the areas in which these 800 people lived.

GELLERMAN: So what did they find? What did the researchers find?

DENISON: Well, they compared this group of 800 people to a group of unexposed individuals and asked the question, how likely was it that these individuals who had been exposed early in life, later in life would engage in so-called "risky behaviors." So this included drug use, smoking, heavy drinking. And what they found was a much higher incidence, some 50 to 60 percent of an increase in the extent of these risky behaviors was observed in the individuals who had been exposed early in life to this solvent compared to those who had not.

GELLERMAN: Can you make the association between something that happens in the womb and behavior so much later in life?

DENISON: Well, there is a lot of additional information that suggests that solvents like PCE are able to do just that. An early life exposure leads to impairment of cognitive abilities, changes in mental disposition and behavior. And what's unique about this study is both the scale of it, the large number of people that were tracked, but also the manifestation of those mental/behavioral changes in directly measurable activities such as drinking and drug use.

GELLERMAN: Of course, there are people who abuse drugs who might never have had exposure to this chemical.

DENISON: This is one of the difficulties in doing human studies. Many effects that we look at have multiple causes, and it's very difficult to ever definitively say that a particular cause is responsible for the entire incidence of a particular outcome. So rather what we're looking for are correlations and in this case the researchers went to significant steps to control for other factors that could potentially confound the results. So it really does look in this study like the strongest correlation is between this early life exposure to a toxic solvent and tying that in this case to a much higher likelihood of developing those risky behaviors later in life.

GELLERMAN: Let's talk about the second study. It took place in New York City, at Mount Sinai. It has to do with something called phthalates. What are phthalates?

DENISON: Phthalates are a group of chemicals that are used widely in commerce today. They're used in everything from cosmetics, to certain types of cleaning products, to a variety of different plastics.

GELLERMAN: So the researchers in New York, they found that there was a relationship between this chemical and overweight kids?

DENISON: That's right. What the researchers studied was a group of about 400 black and Hispanic kids in New York City. They measured several ways in which these children were overweight and they correlated that with the concentrations of these chemicals in the bodies of these children. And they found a very strong relationship. The higher the levels of these chemicals, the more likely they were to be obese at ages six to eight years old.

GELLERMAN: What about things like poor diet, or the kids not getting enough exercise, wouldn't you look at those as variables?

DENISON: Obviously, diet and lifestyle, exercise levels, all affect this. What increasingly the science is pointing to, however, is that early life exposures to certain chemicals can predispose people to being obese later in life. These are chemicals that we know are similar to hormones that are naturally present in the body and they can interfere with the effects of those hormones even at very low doses. They can affect both early development in males and females.

GELLERMAN: The third study you write about are called perfluorinated chemicals. What are those?

Perfluorinated chemicals are the basis for Teflon products, which render surfaces nonstick.

DENISON: These are chemicals that are probably known to most people because of their uses in products like the Teflon brand of products and the Scotchguard brand of products. Typically, they're used as coatings on paper packaging, on textiles, to impart water-resistance or grease-resistance. These chemicals are very persistent in the environment, and in some cases they can build up in our bodies.

This study looked in particular at a group of these chemicals in a very large group of kids that were immunized early in life for diphtheria and other diseases. So then the authors looked for a correlation between the levels of these chemicals and the levels of antibodies that were produced by vaccinations these children had received years earlier. And what they found was that the higher the levels of these chemicals in the bodies of these kids, ages five to seven years old, the lower the levels of antibodies to these two vaccines. So that means that there's at least a potential here that these chemicals are interfering with the effectiveness of those vaccines even years after the initial exposure.

GELLERMAN: Then wouldn't we expect that as they grew older, they might be more susceptible to diseases and the things the vaccines were supposed to prevent?

DENISON: That is certainly the implication. It needs, certainly, further follow-up, but it does suggest that when we are exposed to things early in our lives, that they have some profound effects on our immune system, our mental capacity, our ability to regulate our weight. These kinds of fundamental processes in the human body seem to be being affected by early life exposures.

GELLERMAN: So let me ask you, Dr. Denison. You say we have 27 trillion pounds of these, can we be, you know, effectively protected, or can these chemicals be effectively regulated?

DENISON: Unfortunately, the answer to that question is no. We have a very obsolete chemical safety law that hasn't been amended for 36 years. So we need to update this law, it's called the Toxic Substances Control Act, and it needs to reflect the most recent and best science that's available to us. I think there are, on the margins, certain things that can be done to reduce one's exposure, but I think in the long run it's both unfair and impractical to put the burden on individual consumers to try to figure out where these chemicals are and to try to avoid them. And it's probably a perfect example of where we really need a national solution that makes sure that these chemicals are fully tested before they get into the marketplace so that people, individuals, don't have to worry about themselves and their families.

GELLERMAN: Well, Dr. Denison, thanks a lot.

DENISON: Thank you, Bruce. It's a pleasure to be on your show.

GELLERMAN: Richard Denison is a senior scientist at the Environmental Defense Fund.



Richard Denison’s blog post, “Linking Everyday Chemicals to Disease” with links to summaries of studies

Environmental Defense Fund’s Chemicals and Nanomaterials Blog


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