Sunday, October 10, 2010

ULTRAFINE AIR PARTICLES MAY INCREASE FIREFIGHTERS' RISK FOR HEART DISEASE

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Firefighters are exposed to potentially dangerous levels of ultrafine particulates at the time they are least likely to wear protective breathing equipment. Because of this, researchers believe firefighters may face an increased risk for heart disease from exposures during the fire suppression process.

Coronary heart disease is the No. 1 killer of American firefighters, with many of these incidents taking place during or just after a firefighting incident. Researchers say exposure to these harmful ultrafine air particulates could predispose firefighters to heart disease—particularly in those at a less-than-optimal level of physical fitness or personal health.

In a study conducted collaboratively by the University of Cincinnati (UC), Underwriters Laboratories Inc. and the Chicago Fire Department, researchers have found that more than 70 percent of particulates released during fires are "ultrafine," invisible to the naked eye but able to be inhaled into the deepest compartments of the lung.

These findings were reported in the August 2010 issue of the Journal of Occupational and Environmental Medicine. This study was the first to characterize the size and distribution of particulates, including those in the ultrafine range, during domestic fires.

For this study, researchers conducted a series of simulated house and automobile fires to measure the amount and specific characteristics of breathable particulates released during combustion and, consequently, what firefighters are exposed to during the course of their typical work environment.

Fire suppression takes place in two phases. In the first, known as "knockdown," firefighters squelch the flames with water to avoid fire spread. Workers are required to wear protective breathing equipment during this time to avoid exposure to smoke and toxic gases produced from the process. During "overhaul," the second phase, firefighters enter the structure and work to prevent re-ignition of partially burned material.

Researchers found that levels of ultrafine particulates were highest during overhaul, both in indoor and outdoor structure fires as well as automobile fires.

"Firefighters simply can't avoid inhaling these ultrafine particles when they are not wearing their protective breathing apparatus and, unfortunately, they routinely remove it during overhaul," explains Stuart Baxter, PhD, a collaborator in the study and UC professor of environmental health.

"Standard issue firefighting equipment weighs about 60 pounds, and under the exertion of firefighting the standard air tank only lasts about 20 minutes, so as soon as they determine the situation is safe—typically during overhaul—firefighters shed the protective gear," he adds. "Much of this ultrafine exposure could be avoided through equipment improvements and more rigid safety protocols for fire suppression—including additional workers who could be rotated in to reduce the physical and emotional burden of the job."

(Photo: U. Cincinnati)

University of Cincinnati

SPARKLING DRINKS SPARK PAIN CIRCUITS

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Fizzy beverages light up same pain sensors as mustard and horseradish, a new study shows -- so why do we drink them?

You may not think of the fizz in soda as spicy, but your body does.

The carbon dioxide in fizzy drinks sets off the same pain sensors in the nasal cavity as mustard and horseradish, though at a lower intensity, according to new research from the University of Southern California.

"Carbonation evokes two distinct sensations. It makes things sour and it also makes them burn. We have all felt that noxious tingling sensation when soda goes down your throat too fast," said Emily Liman, senior author of a study published online in the Journal of Neuroscience.

That burning sensation comes from a system of nerves that respond to sensations of pain, skin pressure and temperature in the nose and mouth.

"What we did not know was which cells and which molecules within those cells are responsible for the painful sensation we experience when we drink a carbonated soda," said Liman, an associate professor of neurobiology in the USC College of Letters, Arts and Sciences.

By flowing carbonated saline onto a dish of nerve cells from the sensory circuits in the nose and mouth, the researchers found that the gas activated only a particular type of cell.

"The cells that responded to CO2 were the same cells that detect mustard," Liman said.

These cells express a gene known as TRPA1 and serve as general pain sensors.

Mice missing the TRPA1 gene showed "a greatly reduced response" to carbon dioxide, Liman said, while adding the TRPA1 genetic code to CO2-insensitive cells made them responsive to the gas.

Now that carbonated beverages have been linked to pain circuits, some may wonder why we consume them. A new park in Paris even features drinking fountains that dispense free sparkling water.

Liman cited studies going back as far as 1885 that found carbonation dramatically reduced the growth of bacteria.

"Or it may be a macho thing," she speculated.

If only a sip of San Pellegrino were all it took to prove one's hardiness.

The pain-sensing TRPA1 provides only one aspect of carbonation's sensory experience. In 2009, a group led by Charles Zuker of the University of California, San Diego and Nicholas Ryba of the National Institutes of Health showed that carbonation trips cells in the tongue that convey sourness.

(Photo: Laurie Moore)

University of Southern California

NEW STUDY SHOWS OVER ONE-FIFTH OF THE WORLD'S PLANTS ARE UNDER THREAT OF EXTINCTION

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A global analysis of extinction risk for the world's plants, conducted by the Royal Botanic Gardens, Kew together with the Natural History Museum, London and the International Union for the Conservation of Nature (IUCN), has revealed that the world's plants are as threatened as mammals, with one in five of the world's plant species threatened with extinction. The study is a major baseline for plant conservation and is the first time that the true extent of the threat to the world's estimated 380,000 plant species is known, announced as governments are to meet in Nagoya, Japan in mid-October 2010 to set new targets at the United Nations Biodiversity Summit.

Scientists from the Royal Botanic Gardens, Kew, the Natural History Museum and IUCN Specialist Groups carried out the Sampled Red List Index assessments on a representative sample of the world's plants, in response to the United Nations International Year of Biodiversity and the 2010 Biodiversity Target. The work relied heavily on the vast repository of botanical information held in Kew's Herbarium, Library, Art and Archives, which includes some eight million preserved plant and fungal specimens; on specimens held in the Natural History Museum's own extensive herbarium of six million specimens; on digital data from other sources and on collaboration with Kew's network of partners worldwide.

The Royal Botanic Gardens, Kew's Director, Professor Stephen Hopper, says: "This study confirms what we already suspected, that plants are under threat and the main cause is human induced habitat loss.

"For the first time we have a clear global picture of extinction risk to the world's known plants. This report shows the most urgent threats and the most threatened regions. In order to answer crucial questions like how fast are we losing species and why, and what we can do about it, we need to establish a baseline so that we have something against which to measure change. The Sampled Red List Index for Plants does exactly that by assessing a large sample of plant species that are collectively representative of all the world's plants."

He adds, "The 2020 biodiversity target that will be discussed in Nagoya is ambitious, but in a time of increasing loss of biodiversity it is entirely appropriate to scale up our efforts. Plants are the foundation of biodiversity and their significance in uncertain climatic, economic and political times has been overlooked for far too long.

"We cannot sit back and watch plant species disappear – plants are the basis of all life on earth, providing clean air, water, food and fuel. All animal and bird life depends on them and so do we. Having the tools and knowledge to turn around loss of biodiversity is now more important than ever and the Sampled Red List Index for Plants gives conservationists and scientists one such tool."

Environment Secretary Caroline Spelman says, "This report comes at an important time in the lead up to the major international biodiversity meeting in Nagoya next month. It is deeply troubling that a fifth of the world's plants are facing extinction because of human activity. Plant life is vital to our very existence, providing us with food, water, medicines, and the ability to mitigate and adapt to climate change.

"We must take steps now to avoid losing some of these important species and the UK will show leadership as we look to make progress towards a framework for tackling the loss of the Earth's plant and animal species."

The study revealed:

* About one third of the species (33%) in the sample are insufficiently known to carry out a conservation assessment. This demonstrates the scale of the task facing botanists and conservation scientists – many plants are so poorly known that we still don't know if they are endangered or not

* Of almost 4,000 species that have been carefully assessed, over one fifth (22%) are classed as Threatened

* Plants are more threatened than birds, as threatened as mammals and less threatened than amphibians or corals

* Gymnosperms (the plant group including conifers and cycads) are the most threatened group

* The most threatened habitat is tropical rain forest.

* Most threatened plant species are found in the tropics

* The most threatening process is man-induced habitat loss, mostly the conversion of natural habitats for agriculture or livestock use

The Sampled Red List Index for Plants is part of a worldwide effort to create a tool to monitor the changing status of the world's major groups of plants, fungi and animals. In the future, the project will involve reassessments at regular intervals which will chart the changing fortunes of the world's plants; much like a stock market index shows the ups and downs in the value of shares. This will highlight where and what conservation action is needed to protect plants. However, funding is needed in order to continue this important work.

7,000 plant species drawn from the five major groups of plants were included in the study: Bryophytes (mosses and liverworts), pteridophytes (these are land plants, such as ferns, that produce neither flowers nor seeds and reproduce via spores), gymnosperms (such as conifers and cycads), monocotyledons (one of the major groups of flowering plants including orchids and the economically important grass and palm families) and legumes (the pea and bean family), as representative of the other flowering plants. Both common and rare species were assessed in order to give an accurate picture of how plants are faring around the world.

As the task of assessing the threat to the world's plants (perhaps as many as 380,000 species) would present a much larger challenge than the assessments of threats to birds (10,027 species), mammals (5,490 species) or amphibians (6,285 species), a sampled approach was adopted where 1,500 species were randomly selected from each of the five major groups of land plants. Simulation modelling from the complete IUCN Red List assessments of birds and amphibians confirmed that 1,500 species for each group of plants would provide a representative view of plants overall.

(Photo: Niek Gremme)

Royal Botanic Gardens, Kew

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