Blogs / 80beats

To truly assess the risks posed by a ubiquitous group of chemicals found in everything from vinyl shower curtains to bug spray, researchers need to study their cumulative impact on human health, declares a new report from the National Research Council, a group that advises the government on science and health policy. The chemicals, called phthalates, are used to make plastic products soft and flexible, and are also found in cosmetics, personal-care products, and even pharmaceuticals. In rodent studies exposure to phthalates has been shown to interfere with the development of the male reproductive system, causing infertility, reduced sperm production, undescended testes, penile birth defects and other reproductive-tract malformations [Science News].

Traditionally, health agencies have studied the risk of each chemical individually, but experts say such a process doesn’t accurately reflect human exposure. “It is extremely important to conduct cumulative risk assessments to protect public health,” said [phthalate researcher] Dr. Sheela Sathyanarayana…. “Unlike in scientific experiments, humans are exposed to multiple chemicals everyday,” she said, so combining the chemicals “can help identify how these multiple exposures could be leading to health outcomes in the general population” [Scientific American].

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Even the recycling business is taking a hard hit from the current economic crisis. What in recent years has been a booming market bolstered by a new environmental awakening, has seen a complete reversal of fortunes in recent months as the demand for recycled materials plummeted with a drop in manufacturing. “Before, you could be green by being greedy,” said Jim Wilcox, a professor at the Haas School of Business at the University of California, Berkeley. “Now you’ve really got to rely more on your notions of civic participation” [New York Times].

Mixed paper that sold for $105 a ton in October now sells for as low as $20 a ton. Tin is down from $327 a ton earlier this year to just $5 a ton. Plastic bottles have fallen from 25 cents to 2 cents a pound. Aluminum cans dropped nearly half to about 40 cents a pound, and scrap metal tumbled from $525 a gross ton to about $100 [AP]. Only glass prices are holding because demand is still high. The market for recycled materials is tied closely to new manufacturing, much of which takes place in Asian countries; the recyclables are shipped overseas and new products are shipped back to the U.S. Ordinarily the material would be turned into products like car parts, book covers and boxes for electronics. But with the slump in the scrap market, a trickle is starting to head for landfills instead of a second life [New York Times].

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The standard lab equipment used by scientists to study subtle chemical reactions and examine biological processes may be compromising their results. A new study found that disposable plastic tubes, pipette tips, and culture plates contain compounds that can leach into common solvents. The study is the first to show how thousands of scientists worldwide may be unwittingly contaminating their experiments with plastic lab equipment. “People are clearly aware that plastics can cause problems. Quite remarkably, nobody appears to have done what we were forced to do,” says co-author Andrew Holt [New Scientist].

Holt was studying the effect of drugs on the enzyme monoamine oxidase B (MAO-B) when he noticed strange fluctuations in the results. “We were banging our head against the wall. Finally, we realized that the plastics must be involved in the issue” [Bloomberg]. Holt washed out his equipment with water, methanol or dimethylsulphoxide (DMSO), then analysed what chemicals had leached into the solvents using mass spectrometry. Reporting in Science, Holt and his colleagues show that the plastic tubes they were using were leaching the disinfectant di(2-hydroxyethyl)methyldodecylammonium (DiHEMDA) into water and the lubricant oleamide into methanol and DMSO [Nature News]. Though the amount of leaching varies, some of the plastic equipment produced contaminant concentrations of several hundred parts per million. “The compounds that leached out of the plastic were remarkably potent inhibitors,” [said Holt]. “We were getting variability caused by these leachates that could completely mask the effects of the drugs” [Nature News].

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The toxic chemical melamine that has already contaminated Chinese milk and eggs may also have been widely used in animal feed, according to new reports from the Chinese state media. Chinese consumers were horrified when it was revealed in September that four babies had died and more than 50,000 were sickened due to tainted infant formula, and the outrage grew in October when eggs from four large companies were also found to be tainted. Since then, the widening scandal has caused companies across Asia to recall products made with Chinese milk or eggs, and the new reports suggest that there may be broader recalls to come.

Melamine can be used to make food products appear to have a higher protein content, and the new admission from the state-run media, which usually suppresses bad news, shows that the trick was commonly used. “The feed industry seems to have acquiesced to agree on using the chemical to reduce production costs while maintaining the protein count for quality inspections,” the state-run China Daily said in an editorial. “We cannot say for sure if the same chemical has made its way into other types of food,” the newspaper added [BBC News].

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Researchers have discovered new strains of Pseudomonas bacteria that feed on the PET plastic used in drink bottles, and turn it into a more valuable, biodegradable form of plastic. The discovery suggests a way to keep billions of pounds of discarded plastic out of landfills; a 2006 study [pdf] found that less than 25 percent of PET plastic is currently recycled because the industry doesn’t have enough use for the end product.

Getting high-quality material — such as plastics suitable for packaging food or beverages —- back out of recycled plastic is more expensive than making virgin PET, so most plastic bottles are recycled into lower-grade, and less valuable, plastic. But there’s only so much demand for lower-grade plastics, says microbiologist and coauthor Kevin O’ Connor…. “The problem is that the market [for recycled PET] is saturated” [Science News].

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A “sustainable chemical” company called Genomatica has developed a way to use sugar and genetically engineered bacteria to produce a common industrial chemical that’s usually produced using petroleum, and which is found in everything from Spandex to car bumpers. By using sugar from sugar cane as a feedstock, industrial chemical companies can get a cheaper alternative to petroleum-derived chemicals, while investing in processes that are less polluting and nontoxic, said Genomatica CEO Chris Gann [CNET].

Genomatica produces the chemical, 1,4-butanediol (BDO), by feeding pure glucose derived from sugarcane to E. coli bacteria, which has been engineered to produce BDO. “We have engineered the organism such that it has to secrete that product in order for it to grow,” says [company president] Christophe Schilling…. “The interests of the organism are aligned with our interests: It grows faster when it produces more” [Scientific American].

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New health concerns have been raised about the plastic chemical bisphenol A (BPA); a study suggests that there is a link between high levels of exposure to BPA and an increased risk of heart disease and diabetes. While the new study doesn’t prove a cause and effect relationship, only a correlation, it is the first human survey to follow up on troubling findings from animal studies.

The chemical, which is often found in baby bottles, sports water bottles, and other non-recyclable containers, has gotten several waves of bad press in the past few months. A recent experiment showed that extremely high doses of the chemical damage monkeys’ brains, and other work in animals has suggested that BPA has the potential to disrupt normal hormone signalling by mimicking the natural hormone, oestrogen. Such studies have linked the chemical to a wide range of conditions, including low sperm count, altered fetal development, behavioural disorders in children and prostate cancer [Nature News].

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A new study of a chemical commonly used in plastic containers found that it causes damage to monkey’s brains, raising new concerns over the chemical’s possible effects on humans. The chemical, called bisphenol A or BPA, has been the source of controversy for months as government agencies and scientists have gone back and forth on whether the substance is a health threat. BPA has been in commercial use since the 1950s, and is found in baby bottles, water bottles, in the lining used for canned goods, and many other items.

In the latest study, the research team exposed monkeys to levels of bisphenol A deemed safe for humans by the Environmental Protection Agency and found that the chemical interfered with brain cell connections vital to memory, learning and mood. “Our findings suggest that exposure to low-dose BPA may have widespread effects on brain structure and function,” the authors wrote [Washington Post].

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A new plastic skin that could protect satellites from both searing and freezing temperatures in space could allow for a new generation of miniature spacecraft, researchers announced yesterday. Satellite designers had hit a wall in the quest to create tiny “micro-spacecraft” that weigh no more than 50 pounds because the temperature controls used on conventional satellites can’t be scaled down.

Lead researcher Prasanna Chandrasekhar says the development could allow small companies to send up individual satellites that better suit their needs rather than sharing space on one large one. As might be expected, the technology also has some other potential uses: “For the military, undetectability is also important, either for surveillance applications or when it comes to zapping other satellites,” Chandrasekhar added. “And when it comes to a [nano-spacecraft] less than 5 kilograms (10 pounds), you can’t really detect it unless it’s within a quarter of a mile of you. Larger spacecraft can be detected from farther, and consequently blasted out of the sky” [SPACE.com]. Chandrasekhar’s company, Ashwin-Ushas Corporation, is developing the technology in partnership with NASA.

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The Food and Drug Administration released a draft report on Friday saying that a chemical used in baby bottles and other plastics is not a health threat. The FDA announcement is just the latest twist to a health story that has already alarmed and confused consumers; the chemical, called bisphenol A or BPA, was recently declared a toxin by the Canadian government, and several states are considering banning products that contain it. In April, Wal-Mart announced that its stores will stop selling baby bottles containing BPA.

BPA, a plastic-hardening chemical, is similar to the hormone estrogen. A report in April from the U.S. National Toxicology Program said animal studies suggested its use may pose a cancer risk and lead to early or delayed puberty [Bloomberg]. But the new FDA report says that only small amounts of the chemical leach out from bottles and the lining used for canned foods, and says that it doesn’t pose a threat to infants or adults.

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It’s an odor familiar to anyone who has ever outfitted a home on a budget: “new shower curtain smell.” But the aroma that wafts from a newly purchased vinyl shower curtain is actually a sign that potentially dangerous volatile organic chemicals are being released into the air.

In a new report, an environmental group is sounding an alarm about the possible health effects of those chemicals. Researchers from the Center for Health, Environment & Justice say that pliable plastic shower curtains made of polyvinyl chloride (PVC) release up to 108 chemicals in their first month, and that some of those chemicals are linked to developmental problems, damage to the liver and central nervous system, respiratory harm and reproductive damage [Seattle Post-Intelligencer].

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