FOR IMMEDIATE RELEASE
ACS News Service Weekly PressPac: Wed May 28 16:42:03 EDT 2008
- Lead leaching and faucet corrosion in PVC home plumbing
- Keeping beer fresher
- Mother Nature’s antibacterial dyes: Bright colors and a knock-out punch for germs
- Nano-tech process produces plastics that are 10 times more stretchable
- Bisphenol A: Controversy over widely used plastics chemical spurs product changes, regulatory debate
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News Items in this Edition
Scientists in Virginia are reporting that home plumbing systems constructed with polyvinyl chloride (PVC) plastic pipes may be more susceptible to leaching of lead and copper into drinking water than other types of piping — especially when PVC systems include brass fixtures and pipefittings. The study is scheduled for the June 15 issue of ACS’ Environmental Science & Technology, a semi-monthly journal.
Marc Edwards and colleagues point out that more water purification plants in the United States are using chloramine to treat water. At the same time, builders are plumbing more houses with plastic pipe, rather than copper, to cut costs. Past studies have found that ammonia formed in chloramine-treated water can trigger a series of events that corrode brass faucet components and connectors commonly used in PVC plumbing systems. Corrosion of brass (made with copper, zinc and lead) releases those metals into water pipes and makes faucets prone to failure.
In the new study, researchers sampled water from polyvinyl chloride (PVC), copper, lead, and other pipe material under a range of experimental conditions. They found that corrosive conditions were often worst in plastic pipes, which could be expected to cause higher metal leaching of zinc and lead from brass faucets used in homes and buildings.
Scientists in Venezuela are reporting an advance in the centuries-old effort to preserve the fresh taste that beer drinkers value more than any other characteristic of that popular beverage. Their study, which identifies key substances involved in giving beer an aged or "oxidized" flavor, is scheduled for the May 28 issue of ACS’ Journal of Agricultural and Food Chemistry, a bi-weekly publication.
In the new study, Adriana Bravo and colleagues point out that past efforts to keep beer fresh have focused on protecting beer from contact with the air throughout the brewing process. That focus, however, has resulted in only a relatively small improvement in flavor stability.
The research identified a group of poorly understood substances called alpha-carbonyls as important culprits in the decline in fresh flavor that occurs as beer ages. It also showed that levels of some of these substances could be reduced by adding ingredients that block their formation, thus making beer taste fresher longer.
A strain of marine bacteria produces large amounts of bright red pigments that can be used as a natural dye for wool, nylon, silk and other fabrics, scientists in California are reporting. The dyes from Mother Nature’s palate also have an anti-bacterial effect that could discourage harmful bacteria from growing on socks, undergarments, and other clothing, they report in a study scheduled for the June 6 issue of ACS’ Biotechnology Progress, a bi-monthly journal.
In the new research, graduate student Farzaneh Alihosseini, her adviser Gang Sun and colleagues point out that conventional dyes and pigments used in clothing have several drawbacks. Many are made from non-renewable resources such as petroleum, and are potentially harmful to the environment and human health. In addition, concerns exist about the potential toxicity of existing antibacterial-fabric coatings.
The researchers found that a certain strain of bacteria isolated from marine sediments produces large quantities of bright red pigments called prodiginines that can be used to dye clothing. In laboratory tests, the pigments worked on wool, silk, nylon, and acrylic fabrics as efficiently and effectively as some conventional dyes. The pigments showed strong antibacterial activity against harmful bacteria, including E. coli and Staphylococcus aureus, when applied to most of the fabrics tested.
Move over, Rumplestiltskin. Researchers in China report the first successful “electrospinning” of a type of plastic widely used in automobiles and electronics. The high-tech process, which uses an electric charge to turn polymers into thin fibers in the presence of electricity, produced plastic mats that can stretch 10 times more without breaking than the original material and could lead to new uses for the plastic, they say. Their study is scheduled for the June 10 issue of ACS’ Macromolecules, a bi-weekly journal.
In the new study, Zhao-Xia Guo and colleagues point out that the original plastic, called polyoxymethylene (POM), is an engineering staple known for its metal-like hardness, light weight, and resistance to chemicals. However, the material is relatively brittle, limiting its applications. Although many different types of plastics have been electrospun into fibers with extended uses and properties, researchers have been unable to spin POM into fibers until now, the researchers say.
They report that POM could be turned into nano-sized fibers — thousands of times thinner than the width of a single hair — after first dissolving it in a solution called HFIP and then undergoing electrospinning. The process resulted in POM mats with improved stretchability, or ductility, high porosity, and high surface area. Such features could extend the plastic’s uses to a wide range of industrial, electronic and medical applications, the researchers say.
The controversy over bisphenol A (BPA) is spurring manufacturers to offer BPA-free products and fueling debate over how new chemicals enter the market, according to an article [C&EN link TC] scheduled for the June 2 issue of Chemical & Engineering News, ACS’ weekly newsmagazine. Widely used in consumer products, including baby bottles and beverage bottles, BPA has come under increasing scrutiny by Congress, regulators in the U.S. and abroad, the news media, and other groups over its allegedly harmful health effects.
Written by C&EN Associate Editor Britt Erickson, the story points out that retailers and manufacturers alike are not waiting for scientists to settle the unknowns about BPA, which can have estrogen-like biological effects. Instead, they have been pulling BPA products from store shelves or abandoning its use altogether. Consumers also are avoiding products packaged in containers made with BPA.
More than two billion pounds of BPA are used annually in the United States. Although a growing number of studies suggest that low-level exposure to the chemical can cause cancer, obesity, and other health problems, the plastics industry and federal regulatory agencies insist that the chemical is safe, the article states. Erickson described how Congress entered the fray by launching an investigation into the use of BPA in baby bottles.
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