News / Science & Technology

Tree Bark Shows Global Spread of Toxic Chemicals

Tree Bark Shows Global Spread of Toxic Chemicalsi
March 15, 2013 9:14 PM
The chemicals used to retard fire in consumer products such as furniture and clothing can become toxic pollutants when they wind up in the environment. And they are in the environment - all over the world - in the water, the soil, the plants, and the air. Tracking the spread of these chemicals has been a major challenge, but it just got easier. Erika Celeste reports for VOA on the new technique.
Tree Bark Shows Global Spread of Toxic Chemicals
Erika Celeste
The US Environmental Protection Agency has begun a major new risk assessment of 20 flame-retardant chemicals. These compounds have been widely used for decades in many consumer products, from furniture to sleepwear. But the chemicals are toxic.  And although they are being phased out, they have become a worldwide pollutant and a serious threat to human health.  Measuring their presence in our water, soil, and air has been a major challenge.  But, a new technique promises to make it much easier.

And they are in the environment all over the world; in the water, soil, plants and the air. Tracking the spread of these chemicals has been a major challenge, but it just got easier.

It takes less than 90 seconds for a spark to grow to an inferno. Flame retardants can prevent this.

But Indiana University researcher Amina Salamova points out that when the chemicals evaporate, they become toxic air pollutants.

On the campus of Indiana University, Amina Salamova studies polybrominated diphenyl ethers [PBDEs], and other chemical environmental pollutants. PBDEs are widely used as flame retardants but have been associated with adverse effects on human health.

“They can have an effect on neurological development, on reproductive system, and they can effect your thyroid endocrine system,” said Salamova.

Concerns about those effects have prompted regulatory agencies and some manufacturers to phase out the use of many flame retardant chemicals. But PBDEs can persist for years in the environment, and scientists do not know precisely where or how they spread.

Novel tool

That’s why Salamova and her co-researcher Ronald Hites developed a new technique to measure the presence and concentration of flame retardant chemicals in the air, by sampling the bark of trees.  

“The tree’s ideal because it’s sitting there passively soaking up these compounds out of the atmosphere,” said Hites.

A tree’s bark provides a large surface area that takes in chemicals as both vapor and particles. Also, because a layer of bark remains on the tree for five years or so before being shed, it provides a unique record of the environment over time.

Salamova said the tree-bark approach has many advantages over the current, more complex sampling method, which involves pumping air through expensive equipment, and requires plenty of manpower, and electricity.

“So what I see in future for tree bark is the ability to use this method in developing countries which don’t have a lot of funding for elaborate atmospheric studies. Also we can use this method in remote sites where there is no power,” said Salamova.

Global initiative

With the help of the Global Atmospheric Passive Sampling network, an international monitoring initiative, Salamova and Hites received bark samples from 12 locations around the world, including Norway, the Czech Republic, South Africa, Nepal, Indonesia, the United States and Canada.  

“So this way, you collect about 50 gram of bark, you can collect it from either side of the tree,” said Salamova.

Researchers use a chisel and hammer to tap out a few pieces of bark, wrap them in foil and ship them back to Indiana University for chemical analysis.

Pervasive evidence

Studying those samples in the lab, the researchers found evidence of flame retardants in the atmosphere at all 12 locations. Hites was not surprised to find the highest concentrations at urban sites in Ontario, Canada and around the U.S. Great Lakes.

What was unexpected was the high level of chemicals in some very remote rural regions of Indonesia and Tasmania.

“There’s hardly anybody there. It’s really out of the winds of possible industrial sources. But still these compounds are present there at reasonably high levels, they’re slightly below average, but again measurable levels in the tree bark from Tasmania,” said Hites.

The researchers’ findings, detailed in the journal Environmental Science and Technology, show that these compounds are migrating surprisingly long distances. Salamova says they hope to continue collecting samples to build a global database so scientists and regulatory agencies can understand the pervasiveness of chemical retardants and find ways to remove them from the environment.

You May Like

Photogallery Belgian Security Measures Foreshadow New Normal for Europe

Rising threat of terrorism, disaffected Muslim populations and open borders, along with refugee, migrant crisis, are creating perfect storm for Europe, which some analysts fear continent is ill-suited to weather

Competing Claims of Responsibility for Mali Hotel Attack

Malian authorities ask public for help in identifying gunmen killed in attack, amid conflicting claims of responsibility from multiple jihadist groups active in the country

Video Debt-ridden Refugees Await Onslaught of Lebanese Winter

Aid agencies are attempting to reduce potentially devastating consequences of freezing conditions and snowstorms that killed eight last year, including three Syrian refugees

This forum has been closed.
Comment Sorting
by: Rie K.Maegawa from: Japan
March 31, 2013 1:50 AM
We should rate this experiment highly from the following points. First, this laboratory and field work does not kill any living creatures. Secondly, the samples are really widely collected. As the result, the researchers have found the unexpected high leverl of the chemicals in the very remote rural regions of Indonesia and Tasmania. Building a global database for the data is significant.

by: Chinara from: Azerbaijan
March 19, 2013 8:59 PM
Is it possible to conduct tests on dioxin by this method? As dioxin also is very toxic and persistent pollutant and accumulates in the tissue from all type of environment.

by: cleanair from: Tasmania
March 17, 2013 8:38 AM
Thank you to the researchers who have discovered this process.
I live in Tasmania. There are about half a million people live here.
These results are interesting because our CSIRO tells us we have the cleanest air in the world.
In Response

by: Ian from: USA
March 18, 2013 11:28 AM
You may actually still have the cleanest air in the world.
It is just the whole world's air getting worse

by: Kitagawa Keikoh from: Jiyugaoka, JPN
March 15, 2013 8:00 PM
We are threatening from China's PM2.5 in Japan. They are the worst pollution producer in the world. They don't have enough technology to prevent pollutions and they are wasting energy. That is a new weapon of harasment for neighbor countries.

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
After Paris Attacks, France Steps Up Fight Against ISi
November 24, 2015 3:04 AM
The November 13 Paris attacks have drawn increased attention to Syria, where many of the suspected perpetrators are said to have received training. French President Francois Hollande is working to build a broad international coalition to defeat Islamic State in Syria and in Iraq. Zlatica Hoke reports.

Video After Paris Attacks, France Steps Up Fight Against IS

The November 13 Paris attacks have drawn increased attention to Syria, where many of the suspected perpetrators are said to have received training. French President Francois Hollande is working to build a broad international coalition to defeat Islamic State in Syria and in Iraq. Zlatica Hoke reports.

Video US, Cambodian Navies Pair Up in Gulf of Thailand

The U.S. Navy has deployed one of its newest and most advanced ships to Cambodia to conduct joint training drills in the Gulf of Thailand. Riding hull-to-hull with Cambodian ships, the seamen of the USS Fort Worth are executing joint-training drills that will help build relations in Southeast Asia. David Boyle reports for VOA from Preah Sihanouk province.

Video Americans Sharpen Focus on Terrorism

Washington will be quieter than usual this week due to the Thanksgiving holiday, even as Americans across the nation register heightened concerns over possible terrorist threats. VOA’s Michael Bowman reports new polling data from ABC News and the Washington Post newspaper show an electorate increasingly focused on security issues after the deadly Islamic State attacks in Paris.

Video World Leaders Head to Paris for Climate Deal

Heads of state from nearly 80 countries are heading to Paris (November 30-December 11) to craft a global climate change agreement. The new accord will replace the Kyoto Protocol on Climate Change that expired in 2012.

Video Uncertain Future for Syrian Refugee Resettlement in Illinois

For the trickle of Syrian refugees finding new homes in the Midwest city of Chicago, the call to end resettlement in many U.S. states is adding another dimension to their long journey fleeing war. Organizations working to help them integrate say the backlash since the Paris attacks is both harming and helping their efforts to provide refugees sanctuary. VOA's Kane Farabaugh reports.

Video Creating Physical Virtual Reality With Tiny Drones

As many computer gamers know, virtual reality is a three-dimensional picture, projected inside special googles. It can fool your brain into thinking the computer world is the real world. But If you try to touch it, it’s not there. Now Canadian researchers say it may be possible to create a physical virtual reality using tiny drones. VOA’s George Putic reports.

Video New American Indian Village Takes Visitors Back in Time

There is precious little opportunity to experience what life was like in the United States before its colonization by European settlers. Now, an American Indian village built in a park outside Washington is taking visitors back in time to experience the way of life of America's indigenous people. Carol Pearson narrates this report from VOA's June Soh.

Video Even With Hometown Liberated, Yazidi Refugees Fear Return

While the northern Iraqi town of Sinjar has been liberated from Islamic State forces, it's not clear whether Yazidi residents who fled the militants will now return home. VOA’s Mahmut Bozarslan talked with Yazidis, a religious and ethnic minority, at a Turkish refugee camp in Diyarbakır. Robert Raffaele narrates his report.

Video Nairobi Tailors Make Pope Francis’ Vestments

To ensure the pope is properly attired during his visit, the Kenya Conference of Catholic Bishops asked the Dolly Craft Sewing Project in the Nairobi slum of Kangemi to make the pope's vestments, the garments he will wear during the various ceremonies. Jill Craig reports.

Video Cross-Border Terrorism Puts Europe’s Passport-Free Travel in Doubt

The fallout from the Islamic State terror attacks in Paris has put the future of Europe’s passport-free travel area, known as the "Schengen Zone," in doubt. Several of the perpetrators were known to intelligence agencies, but were not intercepted. Henry Ridgwell reports from London European ministers are to hold an emergency meeting Friday in Brussels to look at ways of improving security.

Video El Niño Brings Unexpected Fish From Mexico to California

Fish in an unexpected spectrum of sizes, shapes and colors are moving north, through El Niño's warm currents from Mexican waters to the Pacific Ocean off California’s coast. El Nino is the periodic warming of the eastern and central Pacific Ocean. As Faiza Elmasry tells us, this phenomenon thrills scientists and gives anglers the chance of a once-in-a-lifetime big catch. Faith Lapidus narrates.

Video Terrorism in Many Forms Continues to Plague Africa

While the world's attention is on Paris in the wake of Friday night's deadly attacks, terrorism from various sides remains a looming threat in many African countries. Nigerian cities have been targeted this week by attacks many believe were staged by the violent Islamist group Boko Haram. In addition, residents in many regions are forced to flee their homes as they are terrorized by armed militias. Zlatica Hoke reports.

Video Study: Underage Marriage Rate Higher for Females in Pakistan

While attitudes about the societal role of females in Pakistan are evolving, research by child advocacy group Plan International suggests that underage marriage of girls remains a particularly big issue in the country. VOA’s Ayesha Tanzeem reports how such marriages leads to further social problems.

VOA Blogs