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Past Shows
February 19, 2005
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Flame Retardants: Friend or Foe?
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Although PBDE levels in breastmilk continue to rise in Canada, benefits of breastfeeding still outweigh potential risks
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You might not know it, but they're everywhere in your house - in your couch, mattress, household electronics, carpets, maybe even your kids' pajamas. They're flame retardants and they slow down or prevent the progression of fire. But they're also in unneccessary places: food, drinking water and air. There is one group of retardants that scientists are particularly worried about. They are called PBDEs - Poly-Brominated Diphenyl Ethers. These are known to leach out of the products they're in, and bioaccumulate in the environment and in humans, particularly in human breast milk. So while there's little doubt they save lives in fires, no one really knows what the long term effects of these chemicals are on humans.
Quirks & Quarks has looked at the research behind this issue and examined the process involved in removing potentially toxic chemicals from our daily lives. These are some of the people we spoke to:
Dr. Mehran Alaee is a research scientist with Environment Canada. He's measured PBDEs in the environment and, while he says the current levels are still fairly low, it's the fact that these chemicals are highly persistent and bioaccumulative that is the real cause for concern.
Dr. Linda Birnbaum is director of the Experimental Toxicology Division of the US Environmental Protection Agency. She says the study of PBDEs is perhaps most easily characterized by what we don't know, rather than what we know. Animal studies suggest a range of negative effects, in particular on developing organisms, but so far there's no direct evidence that these chemicals are bad for humans at the current levels.
Ms. Sonya Lunder is an environmental analyst with the Environmental Working Group, an American research and lobby organization. She says animal studies are all we need to regulate these chemicals. She says if we wait for substantial human data we could cause tremendous damage to generations of children in the process.
Dr. John Jake Ryan is a research scientist with Health Canada, whose work, along with Dr. Alaee's, has helped shape a proposal that PBDEs be added to the list of toxic substances and banned from use in Canada. A final decision has not yet been made.
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Mormon Cricket Movement
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A radio transmitter attached to the back of a Mormon cricket helps researchers determine its movement in the field. Photo by Stephen Ausmus
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Group living is a common phenomenon in nature. One creature that’s taken this to an extreme is the Mormon cricket. These thumb-sized insects can’t fly, so they wander across the American west in the millions. Hordes of these crickets march in bands hundreds of metres across and several kilometres long. But until Dr. Darryl Gwynne, a professor of biology at the University of Toronto at Mississauga, and his colleagues Drs. Greg Sword, from the USDA in Montana, and Pat Lorch, from the University of North Carolina, started studying them, no one knew why they would stick together as a group. It turns out, the insects stay together for protection from predators.
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Flying Ants
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Before the Fall - Courtesy Dr. Stephen Yanoviak |
There are, of course, ants with wings and they do fly. The surprise, for Dr. Michael Kaspari, a professor of Zoology at the University of Oklahoma, and his colleagues, was discovering ants without wings that fly - or at least glide - or at least drop in a controlled way. These ants live in the treetop canopy of the jungles of Central and South America. Their normal home is 30 metres above the jungle floor, and there is always a risk of falling to earth and becoming lost. These ants have developed the ability to control their drop through a very steep glide back to the trunk of the tree they live in when they fall. They also do it backwards. It's a remarkable behaviour that also helps them to escape predators.
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Space Tether
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Space Tether - Courtesy NASA |
Imagine a giant piece of string, 50 kilometres long, floating above our planet. Now, attach a satellite to each end and start the whole thing spinning -- you’d have a space tether. If it were spinning at the proper angle, you could grab onto one end and get boosted to a higher orbit, as it moved up. Let go, and you could sail off toward the moon. That’s the concept Dr. Steven Canfield is working on in his lab at Tennessee Technical University. While they’re still in the concept stage, he and his colleagues think they’ll be able to launch a space tether in ten to 15 years.
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