The proof is in the tree bark

A study by Indiana University researchers found the chlorinated flame retardant Dechlorane Plus in the bark of trees across the northeastern US, with by far the highest concentrations measured near the Niagara Falls, N.Y., factory where this chemical is produced.

The study, by Xinghua Qui and Ronald A. Hites of the IU School of Public and Environmental Affairs, was published online last week by the journal Environmental Science & Technology. Hites is a Distinguished Professor and director of the Environmental Science Research Center at SPEA; Qui is a postdoctoral research scientist.

Hites said the study demonstrates that tree bark can be used as nature's own passive sampling device for detecting the presence and relative concentrations of chemicals in the air. Rough, porous and high in lipids, tree bark soaks up airborne gases and particles, then keeps them protected from the elements.

"It's really a very convenient technique," Hites said. The sampling doesn't hurt the tree, and "you get an integrated measurement of what the tree has been exposed to over the last few years."

The study, "Dechlorane Plus and Other Flame Retardants in Tree Bark from the Northeastern United States," provides the first data on the prevalence of the chemical in the atmosphere outside of the Great Lakes area. It identifies the epicenter of DP concentrations as being near the factory where the chemical is produced by OxyChem (Occidental Petroleum Corp.).

Concentrations in tree bark within a few miles of the factory were several thousand times higher than those found in bark at more distant sampling sites, including Indiana, Virginia and Maryland.

Qui and Hites also used tree bark to sample for brominated flame retardants at northeastern U.S. locations. They found them, but at much lower levels than a previous study by Hites and Lingyan Zhu -- published in 2006 by ES&T -- that found the epicenter of brominated flame retardant concentrations to be near a factory in southern Arkansas that makes these chemicals.

The study also looked for flame retardants in bark samples from Europe and Asia. Bark from China and Korea contained Dechlorane Plus at about 10 times the lowest levels found in the northeastern U.S., suggesting there are Asian sources of this chemical, and they aren't simply reaching Asia through the atmosphere.

Dechlorane Plus has been used for more than 40 years as a flame retardant in electrical cables and wiring, and other products, but little data is available on its toxicity, according to an Environmental Science & Technology article. One of more than 175 types of flame retardants, it was developed as a substitute for the banned, highly chlorinated flame retardant Dechlorane (also known as the insecticide Mirex).

"However, the substitute might not always be as safe as hoped," Qui and Hites write. They point out that Dechlorane Plus is present in air, sediment, fishes and herring gull eggs from in the Great Lakes region, suggesting Dechlorane Plus "might be an environmental problem, especially in the lower Great Lakes region."

Hites said Dechlorane Plus has been added to the list of chemicals sampled on an ongoing basis by the Integrated Atmospheric Deposition Network. Hites heads the U.S. side of the network, a U.S.-Canadian partnership that monitors airborne chemicals at five locations in the Great Lakes region. "The question in the medium term is, are the concentrations of this chemical going up or down -- and if so, how fast?" Hites said.

Source: Indiana University

Related stories:

Mouse studies suggest daily dose of ginkgo may prevent brain cell damage after a stroke
Working with genetically engineered mice, researchers at Johns Hopkins have shown that daily doses of a standardized extract from the leaves of the ginkgo tree can prevent or reduce brain damage after an induced stroke.
Lichens function as indicators of nitrogen pollution in forests
Scientists have found lichens can give insight into nitrogen air pollution effects on Sierra Nevada and San Bernardino mountain ecosystems, and protecting them provides safeguards for less sensitive species.
Cross kingdom conflicts on a beetle's back
Researchers from Harvard Medical School and the University of Madison-Wisconsin have discovered how beetles and bacteria form a symbiotic and mutualistic relationship—one that ultimately results in the destruction of pine forests. In addition, they've identified the specific molecule that drives this whole phenomenon.
Prosthetic vein valve designed to direct blood flow shows promising pre-clinical results
Engineers at the Georgia Institute of Technology have developed a prosthetic vein valve to help improve the lives of those suffering from a condition known as chronic venous insufficiency. The condition, which affects more than seven million people in the United States alone, occurs when valves in a person's veins can no longer ensure a one-way flow of blood back to the heart.
Melting Swiss glacier yields Neolithic trove, climate secrets
Some 5,000 years ago a prehistoric person trod high up in what is now the Swiss Alps, wearing goat leather pants, leather shoes and armed with a bow and arrows.
Second Rare Aye-Aye Born at Duke Lemur Center
(PhysOrg.com) -- Ardrey and Merlin, rare, nocturnal aye-ayes from Madagascar, are pleased to announce the birth of their second child, a male, early on July 23 at the Duke Lemur Center.
Indonesia's 'Tree Man' goes home after wart surgery
An Indonesian villager dubbed "Tree Man" for massive bark-like warts on his body returned home Monday after doctors removed six kilograms (13.2 pounds) of the growths.
Fighting ash borer: To spray or not to spray?
(PhysOrg.com) -- Perhaps the only good news in the Aug. 4 announcement that emerald ash borers have been found in southeastern Wisconsin is that the invasive pest took its time getting here.

News discussion:

Space & Earth science news