We all know that plastics are common in modern life, but science journalist Susan Freinkel says they are really literally everywhere — in our toothbrushes, hair dryers, cell phones, computers, door knobs, car parts — and of course in those ubiquitous plastic bags we get it seems every time we buy anything.
The bags are made from polyethylene, the most common type of plastic in use today. By one estimate, Freinkel says, the amount of polyethylene produced in America every year is nearly equal to the combined mass of every man, woman and child in the country.
Freinkel's new book, Plastic: A Toxic Love Story chronicles the rise of plastic in consumer culture, and its effects on the environment and our health. She notes that plastics have had enormously beneficial impacts — like making blood transfusions safe and common. But scientists are now also finding that phthalate chemicals from IV bags and other plastics are leaching into the fluids we take into our bodies, and the effects of that are just now being understood.
"These chemicals act in a more convoluted and complicated way," Freinkel says. "They interfere with our hormones, and they interfere with the endocrine system, which is the network of glands that orchestrate growth and development. And there's some research showing that DEHP, this chemical that's in vinyl [used in IV bags], has this property. It interferes with testosterone."
But the million dollar question yet to be solved, says Freinkel, is whether prolonged exposure to DEHP and other chemicals alters our bodily systems.
"It's difficult to say what the effects [of exposure] are," she says. "There are animal studies that show, at very high doses, it can be quite hazardous. It is literally toxic to the testicles and can create malformations and damage sperm and create fertility problems later in life. But most people aren't exposed to those kinds of levels — even in hospital settings where you are being transfused for a long time. It's not approaching those levels. It is more subtle, probably."
Problems In Rats
Only a few studies have directly looked at the effects of DEHP exposure in humans. Dr. Shanna Swan at the University of Rochester in Rochester, N.Y., has published several articles on prenatal exposure to phthalates. In one study, she found that newborn baby boys born to mothers with more phthalates in their bodies had a subtle difference in their genitals. That genital abnormality could indicate a disruption in testosterone levels, Freinkel says.
"In rats, that [physical] marker has been associated with a bunch of problems," Freinkel says. "But we don't actually know what it means in humans. ... What it suggests is that these chemicals that we've used for 50 years and assumed to be completely benign may have an impact on health of some people, particularly people who get exposed at critical phases of development."
What The Plastics Industry Says
The plastics industry, Freinkel says, has maintained that vinyl and phthalates are safe. Both the vinyl industry and the American Chemistry Council conduct their own research on the materials they use and have their own trade associations. Freinkel says they're quick to rebut any studies that come out suggesting a correlation between exposure to synthetic chemicals and possible health issues.
"[They say] they've been in use for 50 years, there's no evidence of widespread human problems, and therefore [they ask], 'What's the issue?' " she says. "And they are right — the science on this is still uncertain."
On government regulation of plastics
"Unlike pesticides or drugs, there's no real explicit government regulation on plastics. We have a very fragmented and fairly ineffective patchwork of laws to regulate synthetic chemicals. The central regulation there is something called the Toxic Substances Control Act, which was passed in 1976. People's criticism of that law is that it has tended to treat chemicals as safe until proven to be dangerous. But the way that the law is written is very difficult to establish that a chemical is dangerous because manufacturers do not have to volunteer information about that, and the Environmental Protection Agency is fairly hamstrung in its ability to collect information. When that law was passed, the 60,000 or so chemicals that were then in commerce were simply grandfathered in under the law. Since that time, there have been another 20,000 to 30,000 chemicals that have come onto the market. The EPA has only been able to require reviews of a couple of hundred [types of synthetic chemicals], and it's only been able to actually establish that there were significant hazards that [required] banning in five."
On different types of plastic
"There are a lot of plastics out there. Plastics are not created equal, and I think there are a lot of plastics that we don't have to worry about. I'm not so worried about polyethylene [the stuff of plastic baggies]. I'm not particularly worried about polypropylene, which is the stuff that's used in yogurt containers or margarine tubs. But we know that hazardous chemicals are used in plastics, and some of those plastics will leach chemicals that may be harmful to our health, and we don't know the full extent of that. I'll give you an example, which is PET — polyethylene terephthalate. It's the plastic that's used in soda bottles and water bottles. It's another plastic that we have for decades considered an inert plastic. In recent years, there have been several studies showing that PET can leach some kind of compound that seems to have estrogenic activity — that seems to act like an estrogen. We don't know what that compound is. We don't know whether it's being leached in sufficient quantities to have any impact on human health. The fact that we're suddenly discovering it is a little disconcerting. That said, I think those kinds of findings are why we need to have stronger laws that require manufacturers to demonstrate the safety of chemicals that they put into commerce."
On plastics leaching from baby bottles
"The plastic that used to be used to make baby bottles is a polycarbonate. It's a hard, clear, glasslike plastic, and one of the main ingredients in that is a chemical called bisphenol A (BPA), which is an estrogen mimic. If you look at a diagram of that molecule, it looks just like an estrogen molecule. And bisphenol A has been associated with a bunch of health problems, including obesity, breast cancer, heart disease and others. And when research about bisphenol A started coming out, parents especially were understandably horrified at the thought that the bottles that they were using to feed their babies could potentially be leaching this chemical into their babies. You'd be hard-pressed to buy a baby bottle now that contains bisphenol A. This is one of those instances where the government didn't step in but Walmart did. The big-box stores won't carry BPA bottles. ... Manufacturers are still free to use bisphenol A, but it has acquired such a bad rep that not many do. There are some states and other countries that have outlawed bisphenol A. The problem, of course, is that you end up with this patchwork of regulations and no consistency or guarantee." Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.