Certain manmade chemicals – found in everyday objects – might be scrambling our hormones’ sensitive signaling, says pediatrician Philip Landrigan, director of the Mount Sinai Children’s Environmental Health Center. Dr. Landrigan said scientists are concerned about chemicals called phthalates, widely used to make plastic flexible, and found in baby toys and medical supplies.
Philip Landrigan: Another is a chemical called BPA, found in a lot of plastic water bottles. It’s found in the lining of most all tin cans on the American market, and it gets into food or water from those products, and then into people.
He said that a survey by the Centers for the Disease Control found that phthalates and BPA are found in varying amounts in the bodies of about 80 to 90 percent of Americans. Landrigan said the best evidence we have that these chemicals can affect humans comes from studies of the chemicals effect on other animals.
Philip Landrigan: It’s like having a thunderstorm when you’re trying to speak on the cell phone and the message breaks up. It’s a similar distortion. They do things like change male and female behavior, they make the males more like females, and the females more like males, also these studies have shown very clearly that phthalates are quite toxic to the reproductive organs of males.
Some say Landrigan’s concerns have been called alarmist. He concedes that levels of these chemicals inside most of us are low.
Philip Landrigan: However, we know so little about the toxic effects of these chemicals in humans, that just because the level is low doesn’t mean you don’t have to worry about it.
Landrigan reiterated that scientists are just beginning to do studies to figure out the full effects of these toxins on humans. He explained that the studies of their impact on wildlife have already been going on for a decade or more. He said that, as a pediatrician, he’s especially concerned about the effects of these household chemicals on children, especially in the womb:
Philip Landrigan: There have been a couple of studies published, and some of them are showing that babies who are exposed in the womb to pthalates are having behavior problems, specifically that they’re at greater risk for attention deficit disorder. There have also been studies that have looked at the reproductive organs of baby boys, and these studies have seen some subtle but very real abnormalities in the reproductive structure of baby boys when they’re very carefully examined in the nursery.
He says he finds this very worrisome, and is participating in what’s called the National Children’s Study, which is funded mostly by the U.S. government’s National Institute of Health.
Philip Landrigan: It’s the biggest study of children’s health that’s been undertaken in the United States. This study will follow 100,000 children across the country from conception till age 21. There are also similar multi-year studies of children’s health going on in Europe and Asia. All of these studies have the common purpose of discovering links between [chemical] exposures in early life – even in the womb – and disease and dysfunction in children.
Dr. Landrigan said one of the driving forces behind this study is that researchers have come to realize that humans are most vulnerable to these chemicals in the womb, and at very young ages – especially those that affect hormones. He explained that hormones exist in a very delicate balance in the human body, and that tiny amounts have big effects: they help the cells of the body communicate with one another.
Philip Landgrigan: The ways cells communicate with each other in the human body is that certain cells release chemicals in the bloodstream that carry messages to other cells; to grow, or to multiply, or to divide, or to shut down. And it takes only tiny, tiny amounts of these signaling chemicals in the blood stream – hormones – to send these signals.
Beth Lebwohl researches, writes and helps produce science content in audio and video formats for EarthSky. She is one of the authors on EarthSky.org, a script-writer for our podcasts, and helps host our English science podcasts in 90-second, 8-minute and 22-minute formats. Beth came to EarthSky in 2006 from the American Museum of Natural History's Department of Astrophysics, where she was surrounded by some of the greatest telescope-building, equation-wielding, code-writing physicists of our time. And they made her think . . . this science thing . . . it's pretty cool.