A recent study shows residues from household plastic products in the human body. I have spoken to some degree about the possibility of toxic effects of the excessive use of plastics, now it appears as though the dangers go further than the base chemicals of plastics and the body can actually reatin some polymer as well.
Article courtesy of Science News Online.
How Plastic We've Become
Our bodies carry residues of kitchen plastics
Janet Raloff
In the 1967 film classic The Graduate, a businessman corners Benjamin Braddock at a cocktail party and gives him a bit of career advice. "Just one word…plastics."
Although Benjamin didn't heed that recommendation, plenty of other young graduates did. Today, the planet is awash in products spawned by the plastics industry. Residues of plastics have become ubiquitous in the environment—and in our bodies.
A federal government study now reports that bisphenol A (BPA)—the building block of one of the most widely used plastics—laces the bodies of the vast majority of U.S. residents young and old.
Manufacturers link BPA molecules into long chains, called polymers, to make polycarbonate plastics. All of those clear, brittle plastics used in baby bottles, food ware, and small kitchen appliances (like food-processor bowls) are made from polycarbonates. BPA-based resins also line the interiors of most food, beer, and soft-drink cans. With use and heating, polycarbonates can break down, leaching BPA into the materials they contact. Such as foods.
And that could be bad if what happens in laboratory animals also happens in people, because studies in rodents show that BPA can trigger a host of harmful changes, from reproductive havoc to impaired blood-sugar control and obesity (SN: 9/29/07, p. 202).
For the new study, scientists analyzed urine from some 2,500 people who had been recruited between 2003 and 2004 for the National Health and Nutrition Examination Survey (NHANES). Roughly 92 percent of the individuals hosted measurable amounts of BPA, according to a report in the January Environmental Health Perspectives. It's the first study to measure the pollutant in a representative cross-section of the U.S. population.
Typically, only small traces of BPA turned up, concentrations of a few parts per billion in urine, note chemist Antonia M. Calafat and her colleagues at the Centers for Disease Control and Prevention. However, with hormone-mimicking agents like BPA, even tiny exposures can have notable impacts.
Overall, concentrations measured by Calafat's team were substantially higher than those that have triggered disease, birth defects, and more in exposed animals, notes Frederick S. vom Saal, a University of Missouri-Columbia biologist who has been probing the toxicology of BPA for more than 15 years.
The BPA industry describes things differently. Although Calafat's team reported urine concentrations of BPA, in fact they assayed a breakdown product—the compound by which BPA is excreted, notes Steven G. Hentges of the American Chemistry Council's Polycarbonate/BPA Global Group. As such, he argues, "this does not mean that BPA itself is present in the body or in urine."
On the other hand, few people have direct exposure to the breakdown product.
Hentges' group estimates that the daily BPA intake needed to create urine concentrations reported by the CDC scientists should be in the neighborhood of 50 nanograms per kilogram of bodyweight—or one millionth of an amount at which "no adverse effects" were measured in multi-generation animal studies. In other words, Hentges says, this suggests "a very large margin of safety."
No way, counters vom Saal. If one applies the ratio of BPA intake to excreted values in hosts of published animal studies, concentrations just reported by CDC suggest that the daily intake of most Americans is actually closer to 100 micrograms (µg) per kilogram bodyweight, he says—or some 1,000-fold higher than the industry figure.
Clearly, there are big differences of opinion and interpretation. And a lot may rest on who's right.
Globally, chemical manufacturers produce an estimated 2.8 million tons of BPA each year. The material goes into a broad range of products, many used in and around the home. BPA also serves as the basis of dental sealants, which are resins applied to the teeth of children to protect their pearly whites from cavities (SN: 4/6/96, p. 214). The industry, therefore, has a strong economic interest in seeing that the market for BPA-based products doesn't become eroded by public concerns over the chemical.
And that could happen. About 2 years after a Japanese research team showed that BPA leached out of baby bottles and plastic food ware (see What's Coming Out of Baby's Bottle?), manufacturers of those consumer products voluntarily found BPA substitutes for use in food cans. Some 2 years after that, a different group of Japanese scientists measured concentrations of BPA residues in the urine of college students. About half of the samples came from before the switch, the rest from after the period when BPA was removed from food cans.
By comparing urine values from the two time periods, the researchers showed that BPA residues were much lower—down by at least 50 percent—after Japanese manufacturers had eliminated BPA from the lining of food cans.
Concludes vom Saal, in light of the new CDC data and a growing body of animal data implicating even low-dose BPA exposures with the potential to cause harm, "the most logical thing" for the United States to do would be to follow in Japan's footsteps and "get this stuff [BPA] out of our food."
Broken into two sections due to size.
Article courtesy of Science News Online.
How Plastic We've Become
Our bodies carry residues of kitchen plastics
Janet Raloff
In the 1967 film classic The Graduate, a businessman corners Benjamin Braddock at a cocktail party and gives him a bit of career advice. "Just one word…plastics."
Although Benjamin didn't heed that recommendation, plenty of other young graduates did. Today, the planet is awash in products spawned by the plastics industry. Residues of plastics have become ubiquitous in the environment—and in our bodies.
A federal government study now reports that bisphenol A (BPA)—the building block of one of the most widely used plastics—laces the bodies of the vast majority of U.S. residents young and old.
Manufacturers link BPA molecules into long chains, called polymers, to make polycarbonate plastics. All of those clear, brittle plastics used in baby bottles, food ware, and small kitchen appliances (like food-processor bowls) are made from polycarbonates. BPA-based resins also line the interiors of most food, beer, and soft-drink cans. With use and heating, polycarbonates can break down, leaching BPA into the materials they contact. Such as foods.
And that could be bad if what happens in laboratory animals also happens in people, because studies in rodents show that BPA can trigger a host of harmful changes, from reproductive havoc to impaired blood-sugar control and obesity (SN: 9/29/07, p. 202).
For the new study, scientists analyzed urine from some 2,500 people who had been recruited between 2003 and 2004 for the National Health and Nutrition Examination Survey (NHANES). Roughly 92 percent of the individuals hosted measurable amounts of BPA, according to a report in the January Environmental Health Perspectives. It's the first study to measure the pollutant in a representative cross-section of the U.S. population.
Typically, only small traces of BPA turned up, concentrations of a few parts per billion in urine, note chemist Antonia M. Calafat and her colleagues at the Centers for Disease Control and Prevention. However, with hormone-mimicking agents like BPA, even tiny exposures can have notable impacts.
Overall, concentrations measured by Calafat's team were substantially higher than those that have triggered disease, birth defects, and more in exposed animals, notes Frederick S. vom Saal, a University of Missouri-Columbia biologist who has been probing the toxicology of BPA for more than 15 years.
The BPA industry describes things differently. Although Calafat's team reported urine concentrations of BPA, in fact they assayed a breakdown product—the compound by which BPA is excreted, notes Steven G. Hentges of the American Chemistry Council's Polycarbonate/BPA Global Group. As such, he argues, "this does not mean that BPA itself is present in the body or in urine."
On the other hand, few people have direct exposure to the breakdown product.
Hentges' group estimates that the daily BPA intake needed to create urine concentrations reported by the CDC scientists should be in the neighborhood of 50 nanograms per kilogram of bodyweight—or one millionth of an amount at which "no adverse effects" were measured in multi-generation animal studies. In other words, Hentges says, this suggests "a very large margin of safety."
No way, counters vom Saal. If one applies the ratio of BPA intake to excreted values in hosts of published animal studies, concentrations just reported by CDC suggest that the daily intake of most Americans is actually closer to 100 micrograms (µg) per kilogram bodyweight, he says—or some 1,000-fold higher than the industry figure.
Clearly, there are big differences of opinion and interpretation. And a lot may rest on who's right.
Globally, chemical manufacturers produce an estimated 2.8 million tons of BPA each year. The material goes into a broad range of products, many used in and around the home. BPA also serves as the basis of dental sealants, which are resins applied to the teeth of children to protect their pearly whites from cavities (SN: 4/6/96, p. 214). The industry, therefore, has a strong economic interest in seeing that the market for BPA-based products doesn't become eroded by public concerns over the chemical.
And that could happen. About 2 years after a Japanese research team showed that BPA leached out of baby bottles and plastic food ware (see What's Coming Out of Baby's Bottle?), manufacturers of those consumer products voluntarily found BPA substitutes for use in food cans. Some 2 years after that, a different group of Japanese scientists measured concentrations of BPA residues in the urine of college students. About half of the samples came from before the switch, the rest from after the period when BPA was removed from food cans.
By comparing urine values from the two time periods, the researchers showed that BPA residues were much lower—down by at least 50 percent—after Japanese manufacturers had eliminated BPA from the lining of food cans.
Concludes vom Saal, in light of the new CDC data and a growing body of animal data implicating even low-dose BPA exposures with the potential to cause harm, "the most logical thing" for the United States to do would be to follow in Japan's footsteps and "get this stuff [BPA] out of our food."
Broken into two sections due to size.
mad
