Researchers have known for years that phthalates, a family of chemicals found in paints, pesticides, and consumer products like shampoo, soap, and makeup, can have detrimental effects on genital and reproductive development in male rats. Now for the first time, a study looks at possible impacts on male human babies. Host Steve Curwood talks to Shanna Swan, one of the study's authors, about the results.
CURWOOD: Studies by the Centers for Disease Control show that most people in the United States carry in their bodies concentrations of a family of synthetic chemicals known as phthalates. Phthalates are commonly found in plastics, pesticides, and personal care products like shampoos, soaps, and makeup. Phthalate exposure has been linked to malformed sex organs in male lab animals. Now, for the first time, there is a human study linking mothers exposed to phthalates to genital birth defects in male infants. The research is in the journal Environmental Health Perspectives and its’ lead author, Doctor Shana Swan, of the University of Rochester Medical School, joins me now. Dr. Swan, what exactly did you find?
SWAN: Well, um, we found that when the mother had higher levels of certain phthalates in her urine while she was pregnant, the boys produced had incomplete masculinization. Specifically, we found that a measurement that we call “anal-genital distance” was shorter when the mother was exposed to higher levels of certain phthalates. So, what is that? Well, the anal-genital distance can be measured pretty easily in young baby boys from the center of the anus to the upper insertion of the penis. It’s about twice as long in boys as in girls. In addition, the boys were more likely to have less fully descended testicles and also shorter or smaller penis size as measured by the volume. And their scrotums were smaller and less distinct.
CURWOOD: Now, just because this distance was shorter and the genitals were smaller doesn’t necessarily mean that this is a bad thing, does it? I mean, some people are shorter than others, that’s not necessarily a bad thing. Or is it a bad thing?
SWAN: Having a shorter anal-genital distance is a reflection of less virilization– pushes the boy toward the direction of the feminine. And, um, this is something that, in rodents, has led to a lot of problems later in the rodents’ lives such as decreased fertility, decreased sperm count, and eventually testicular cancer.
CURWOOD: Now you’re study says that as many as a quarter of the women in this country have levels of phthalates in their bodies higher than the levels you found in your research. Tell me, uh, to what extent do these chemicals accumulate in body tissue? And what’s the pathway for exposure to them, in adults?
SWAN: Right. Well, actually, for most of the phthalates we studied, and particularly the four that we found associated with genital development in boys, they are present in almost every female of reproductive age in the United States. So they’re extremely common. And the pathway is really unclear. They can come in through dermal exposure, through cosmetics, for example, putting on hand cream and so on. They can come in through your food or through your water. So we have ingestion, we have dermal exposure. And inhalation is probably the least likely, although they are in hairsprays and perfumes as well. So we have multiple routes of exposure and, um, multiple sources as well.
CURWOOD: What, if anything, can be done to reverse this stunted development of boys’ genital tracts in the womb? To what extent are supplements available that mothers could take to counteract the effects of these substances? Or substances that maybe they should avoid?
SWAN: Um, nothing is known about whether this is reversible, but from all the evidence we have, at least in rodents, this is a permanent change. There’s probably nothing that can be done once the development has been established. As to what women could do to prevent it, that’s very difficult, because consumers cannot know at this point what’s in the products they buy. So if you go to the store to buy, uh, makeup or some other household or personal care product, you will not know whether there’s a phthalate in there. I think an action that could be taken is we need to press for more consumer right to know about what’s in the products that we buy and put in our bodies and give to our children.
CURWOOD: Shana Swan is a professor of obstetrics and gynecology at the University of Rochester. Her study is published in Environmental Health Perspectives. Thanks for taking this time with me today, Dr. Swan.
SWAN: Nice to talk to you, Steve.
CURWOOD: Coming up: From cost to conservation. Turning the threat of forest fires into an opportunity to generate greener power. Keep listening to Living on Earth.
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