Special ES&T issue examines effects of emerging contaminants on people, planet

Not so long ago, the notion that particles 80,000 times thinner than a human hair could somehow self-assemble and cause harmful effects in the water, air and perhaps even cells seemed far-fetched. But today the quest to understand nanoparticles and other emerging contaminants and discover ways to cope with them is one of the hottest and most critical areas in chemistry research.

More than 40 scientific papers on an array of these potentially problematic compounds - including pharmaceuticals, disinfectant by-products and fluorochemicals - are highlighted in the Dec. 1 issue of the American Chemical Society journal, Environmental Science & Technology. These articles examine what chemists and engineers are learning about emerging contaminants as well as what can be done to remediate those already in the environment and prevent others from getting there.

"(This) special issue not only publishes new knowledge on chemicals and organisms of recent interest, but it also suggests some newly realized effects on humans and the ecology of our planet," says Editor-in-Chief Jerald Schnoor, Ph.D. "It packs years of research into one broad reference on the fate, transport and effects of contaminants in water, air, soil and even our bodies today."

Here are a few selected highlights from the issue, including a look at how buckyballs can damage DNA and how trees could help curb the spread of NDMA into groundwater. To download manuscripts, please click on the links provided with each item. Please cite Environmental Science & Technology, or the American Chemical Society, as the source of this information.

Buckyballs that clump together in water can induce DNA damage in human lymphocytes, according to Volodymyr Tarabara, Ph.D., and his colleagues at Michigan State University and India's Industrial Toxicology Research Centre. The study, believed to be the first of its kind, raises new concerns about the potential risk these nanoparticles pose to human health and the environment, the researchers say.

A buckyball is a spherical fullerene - a soccer ball-shaped molecule comprised of 60 carbon atoms. Buckyballs have been touted for their potential applications in everything from drug delivery to energy transmission. But recent studies have shown that when buckyballs combine into nano-sized clumps known as nC60, they can promote cellular damage. This new study goes a step further, demonstrating "a strong correlation between the presence of nC60 and DNA damage" to human lymphocytes, the researchers conclude. The study is the first to assess the genotoxicity of nC60 mixed into water. Water is a likely pathway for future human exposure to buckyballs and other nanoparticles, Tarabara says.

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PBDE ( polybrominated diphenyl ether) flame retardants amass in the top predator fish in the Great Lakes to the same extent as PCBs, a potentially harmful group of compounds banned 30 years ago, according to Deborah Swackhamer, Ph.D., and colleagues at the University of Minnesota. The study is the first to measure PBDEs in water and the extent that these compounds bioaccumulate in an aquatic food chain. The researchers concluded certain PBDE levels found in lake trout were 10 million times higher than in the surrounding water. Swackhamer estimates that a person eating one lake trout fillet would consume more PBDEs than from a lifetime of drinking Lake Michigan water. The finding could help explain why human PBDE levels in North American are higher than elsewhere in the world, she said. Toxicology testing suggests that, like PCBs (polybrominated biphenyls), PBDEs may be harmful to humans.

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A pair of new remediation techniques could help eliminate NDMA (N-nitrosodimethylamine) from ground and drinking water. NDMA, which is classified as a probable human carcinogen by the Environmental Protection Agency, often forms when water is disinfected with chlorine and especially chloramine. NDMA is difficult to remove from water using conventional methods, but in a laboratory study, Martin Reinhard, Ph.D., and his colleagues at Stanford University and the University of Illinois, Urbana-Champaign, used noble metal catalysts, such as palladium, to destroy NDMA under ambient conditions. When the technology is further developed, the researchers say NDMA concentrations could possibly be reduced to a few parts per trillion. The new process, they note, potentially could be used to treat a broad spectrum of contaminants.

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NDMA also can be formed by oxidation of UDMH (1, 1-dimethylhydrazine), a compound used in rocket fuel production. As a result, NDMA and a co-contaminant, perchlorate, which also is used in rocket fuel and munitions, often infiltrate ground water near aerospace facilities. However, Valentine Nzengung, Ph.D., and colleagues at the University of Georgia found that pre-rooted trees, such as willows and poplars that soak up tremendous amounts of water, effectively removed up to 94 percent of the NDMA in 50 days and 100 percent of the perchlorate in 70 days, at concentration ranges found in most ground water. The study is the first to suggest a cost-effective way to use plants and trees to manage the spread of groundwater contaminated with NDMA or NDMA and perchlorate, Nzengung says.

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Byproducts produced during the manufacture of single-walled carbon nanotubes appear to have a disruptive effect on copepods, a group of small crustaceans, which are a critical food source for shrimp, crabs and fish in coastal rivers and estuaries, according to Thomas Chandler, Ph.D., and colleagues at the University of South Carolina. Copepods exposed to these impurities, called fluorescent nanocarbon byproducts, took longer to reach maturity, had more reproductive problems and had higher mortality rates than copepods that weren't exposed to these compounds. Single-walled carbon nanotubes, which are about 80,000 times thinner than a human hair and are used in electronic equipment and sporting goods, had no adverse effects on copepods in this study. The findings suggest that nanoscale manufacturing byproducts could upset coastal food chains if released into rivers and estuaries, the researchers say. These byproducts, they add, should be monitored or possibly regulated in the future.

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A podcast featuring guest editors Jennifer Field of Oregon State University, Joan Rose of Michigan State University, and Annette Johnson of the Swiss Federal Institute of Aquatic Science and Technology is available at: http://pubs.acs.org/subscribe/journals/esthag/40/i23/html/120106feature_intro_mp3.html

The American Chemical Society - the world's largest scientific society - is a nonprofit organization chartered by the U.S. Congress and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.