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One less risk factor for breast cancer. School of Medicine researchers have found that light consumption of alcohol is not associated with an increased risk of breast cancer in women. Their results, to be published in an upcoming issue of the American Journal of Epidemiology, are based on work with the Framingham Study, the world's longest-running epidemiological study of cardiovascular disease, based in Framingham, Mass.

None of the women in the three drinking categories (up to half a drink, a half to one and a half drinks and more than one and a half drinks per day) showed an increased risk of breast cancer, even when compared with women who consumed no alcohol at all. Senior author Dr. R. Curtis Ellison, chief of the preventive medicine and epidemiology section at MED, explains, "While the rates of breast cancer in the alcohol drinkers were actually slightly lower than those of nondrinkers, the differences were not statistically significant. In any case, this study shows that light alcohol consumption does not increase the risk of breast cancer."

Lead author Yuqing Zhang, assistant professor of medicine and epidemiology, stresses that this study examined only light alcohol consumption (as opposed to heavy, defined as two or more drinks a day) with breast cancer risk. "Most American women average less than one drink per day," adds Ellison. "For them, the results of this study are reassuring."

Even Matthew Longnecker, the doctor in the National Institute of Environmental Health Services who in 1994 had found evidence of a 10 percent increased risk of breast cancer in women who average one drink a day, stands by this new study. In an editorial accompanying the paper, he notes that "light to moderate alcohol consumption has been shown to reduce women's overall risk of dying from any cause by 5 to 20 percent . . . decreasing alcohol consumption is likely to have a modest, if any, effect on a woman's mortality."

"Because light alcohol consumption markedly reduces a woman's risk of heart disease and stroke, leading causes of death," Ellison says, "longevity is greater for light drinkers than for abstainers."

Hear ye. Ever wonder why when listening to the radio the sound appears to comes from the speakers, but when you put on headphones, the sound seems to be right inside your head? Thanks to ENG Professor of Biomedical Engineering Steven Colburn, director of the Hearing Research Center, and Abhijik Kulkarni, an associate at the center, the sounds in your head might soon be moved to the virtual outdoors.

That's because the ears, like the eyes, literally have different perspectives on the world. "Outside" sound usually reaches each ear at a slightly different time and intensity level, creating what scientists call "binaural difference cues," which the brain computes after information from each ear arrives.

The pinna, or external ear structure, also plays a role in locating a sound, Colburn explains. "It creates what we call a head-related transfer function -- increasing, reducing, or delaying sound waves before they hit the eardrum." Working together, differences in perspective and the head-related transfer function allow us to locate a sound's direction. Wearing headphones eliminates these functions.

Colburn and Kulkarni have found a way to reproduce this natural phenomenon with an electronic filtering system called virtual auditory space, which creates the illusion that sound is coming from outside the head. Key to their system was identifying the level of filtering necessary to match the human ear in creating this effect. "Luckily, it's not a finely tuned measurement," says Colburn. "Our test subjects couldn't distinguish a virtual external sound from a real one even when most of the fine filtering was removed."

The researchers say these filters could be used in military simulators and computer games and would give hearing researchers more control over auditory stimuli in their experiments. The study ran in the December 1998 issue of Nature.

"Research Briefs" is written by Joan Schwartz in the Office of the Provost. To read more about BU research, visit


15 May 2003
Boston University
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