Wednesday, January 18, 2006

Dogs Can Smell Cancer, but Not Bombs on Subways

Brian
Mrs. GR and I have been talking about purchasing The Official Dog of SuedO Apmuza, and I wish to change my preference (previously presa canario) to any dog capable of telling me if I develop cancer:
In the small world of people who train dogs to sniff cancer, a little-known Northern California clinic has made a big claim: that it has trained five dogs - three Labradors and two Portuguese water dogs - to detect lung cancer in the breath of cancer sufferers with 99 percent accuracy.

. . . .

In [research director Michael] McCulloch's study, the five dogs, borrowed from owners and Guide Dogs for the Blind, were trained as if detecting bombs. They repeatedly heard a clicker and got a treat when they found a desired odor in many identical smelling spots.

The clinic collected breath samples in plastic tubes filled with polypropylene wool from 55 people just after biopsies found lung cancer and from 31 patients with breast cancer, as well as from 83 healthy volunteers.

The tubes were numbered, and then placed in plastic boxes and presented to the dogs, five at a time. If the dog smelled cancer, it was supposed to sit.

For breath from lung cancer patients, Mr. McCulloch reported, the dogs correctly sat 564 times and incorrectly 10 times. (By adjusting for other factors, the researchers determined the accuracy rate at 99 percent.)

For the breath from healthy patients, they sat 4 times and did not sit 708 times.
Link (submitted by Ian). While dogs may be great at telling you whether you have cancer, they're not as excellent as we think at telling you whether you are about to explode:
The London bombings last summer highlighted the vulnerability of mass transit to terror attacks, and scientists are pushing to develop new gadgets to detect explosives and other hazards. But as some of these technologies come up short or prove tricky to implement, some law-enforcement agents have begun to speak wistfully about the olfactory prowess of man's best friend. As sensitive as the canine nose may be, however, dogs are not well-suited to the challenges of mass transit. It's just not where they do their best work.

Dogs are acclaimed for detecting minuscule amounts of myriad compounds. Their noses are 100 times to 10,000 times more sensitive than human noses, depending on the scent. And they can identify particular odors within a complex mixture—which should be useful for detecting explosives, since many are a potpourri of scents. (There are around 19,000 known smells associated with explosives, grouped into chemical categories of nitrate compounds and acid salts, as well as chlorates, peroxides, acids, and others.) Dogs can also home in on target scents, even when other strong smells are present. Well-trained canines have proved valuable in searching for narcotics and explosives in airport luggage, sniffing out land mines in places like Afghanistan, and ensuring that there are not bombs behind the wall panels in rooms where high-level meetings are to take place. A California clinic now claims it has trained three Labradors and two Portuguese water dogs to detect lung cancer in the breath of patients. Dogs' accuracy is the stuff of legend, which is why, in urban police departments, dogs are considered strong deterrents to would-be criminals.

. . . .

For one thing, dogs work best in quiet places that have been cleared of people other than their handlers. In airports, they are best at sniffing luggage in secluded baggage areas. Canine performance has also been shown to "fall off exponentially," the bomb expert said, because of distractions like gusts of air, noise, food, and people—all realities, of course, of mass transit. Bomb-sniffing is also exhausting work—a kind of sensory sprint—that dogs can't sustain for more than 20 or 30 minutes out of every couple of hours. And as they move through an area, dogs need constant reassurance and reward; if they aren't talked to, given an explosive to find now and then, and allowed to run back and forth, they may lose interest in the game. The explosives and the scampering would be hard to offer in the subway.

. . . .

In addition, dogs probably can't be trained to detect the kind of explosives many experts increasingly worry about. Peroxide-based substances like TATP—used by shoe bomber Richard Reid and some recent terrorists in Israel—are unusually unstable—prone to blow up or otherwise react in air. That makes it difficult, if not impossible, to train dogs to recognize their scent, because to do so requires repeated reinforcement and practice, and that would be dangerous for the canines and their handlers.
Link. So, all things considered, I'd rather have a cancerdog. Or a helper monkey.

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