A Healthy Diet may keep Chronic Lung Disease at Bay

A diet rich in fruits, vegetables, fish, poultry and whole grain foods may offer protection against chronic lung disease, a new study suggests, in addition to the other benefits of such a regimen.

Researchers studied more than 42,000 male health professionals enrolled in a long-term study that began in 1986. All filled out food frequency questionnaires, and the scientists ranked them by how closely they followed what the authors call the “prudent” diet, or how much they stuck to a “Western” diet dominated by refined grains, cured and red meats, sweets and French fries.

After adjusting for age, smoking and other factors, the scientists found that the more strictly a person followed the prudent diet, the lower the risk of chronic obstructive pulmonary disease, or C.O.P.D., the umbrella term for chronic bronchitis and emphysema. Compared with the one-fifth of people with the highest intake of foods from the prudent diet, the one-fifth with the lowest intake were twice as likely to suffer from newly diagnosed C.O.P.D.

At the same time, the one-fifth of men who followed the Western diet most closely were more than four and a half times as likely to be diagnosed with chronic pulmonary disease as the one-fifth who ate the least from that menu.

Raphaëlle Varraso, the lead author, said that fruits, vegetables and omega-3 fatty acids probably explained the protective effect, and that red meat, cured meat and French fries actively increased the risk. Dr. Varraso was at the Harvard School of Public Health when the study was done, and is now a researcher at the National Institute for Health and Medical Research in France.

Treatment of Depression may lead to Longer Life

Treating depression in older adults may be a life-saving intervention, a new study suggests.

It has been known for some time that depressed people are more likely to die, but it has never been clear that treating their depression would help extend their lives.

Researchers studied 1,226 patients over 60 in the care of general practice doctors; of those, 599 met the diagnostic criteria for either major depression or clinically significant minor depression. The researchers randomly assigned about half the patients to a depression treatment program within the general practice that included psychotherapy and drugs. The study was published in the May 15 issue of The Annals of Internal Medicine.

The scientists found no difference in the survival of people with minor depression in the treated or untreated groups. But after controlling for age, sex, smoking status, education level and current physical illnesses, people with major depression who were treated were about half as likely to die during a five-year follow-up as those who were left untreated. For reasons that are unclear, the reduction in deaths seemed to come almost entirely in the group of patients who had cancer.

The authors acknowledge that they cannot rule out the possibility that the reduction in deaths was caused by some factor other than the treatment for depression, and they also recognize that errors in diagnosis could have affected their results.

Still, said Dr. Joseph J. Gallo, the lead author and an associate professor of family practice at the University of Pennsylvania, “This shows that for people who meet the criteria for major depression, it’s important to get treatment, whether it’s psychotherapy or medication, and a place to begin can be with one’s own doctor.”

Study Traces Cat’s Ancestry to Middle East

Some 10,000 years ago, somewhere in the Near East, an audacious wildcat crept into one of the crude villages of early human settlers, the first to domesticate wheat and barley. There she felt safe from her many predators in the region, such as hyenas and larger cats.

The rodents that infested the settlers’ homes and granaries were sufficient prey. Seeing that she was earning her keep, the settlers tolerated her, and their children greeted her kittens with delight.

At least five females of the wildcat subspecies known as Felis silvestris lybica accomplished this delicate transition from forest to village. And from these five matriarchs all the world’s 600 million house cats are descended.

A scientific basis for this scenario has been established by Carlos A. Driscoll of the National Cancer Institute and his colleagues. He spent more than six years collecting species of wildcat in places as far apart as Scotland, Israel, Namibia and Mongolia. He then analyzed the DNA of the wildcats and of many house cats and fancy cats.

Five subspecies of wildcat are distributed across the Old World. They are known as the European wildcat, the Near Eastern wildcat, the Southern African wildcat, the Central Asian wildcat and the Chinese desert cat. Their patterns of DNA fall into five clusters. The DNA of all house cats and fancy cats falls within the Near Eastern wildcat cluster, making clear that this subspecies is their ancestor, Dr. Driscoll and his colleagues said in a report published Thursday on the Web site of the journal Science.

The wildcat DNA closest to that of house cats came from 15 individuals collected in the deserts of Israel, the United Arab Emirates, Bahrain and Saudi Arabia, the researchers say. The house cats in the study fell into five lineages, based on analysis of their mitochondrial DNA, a type that is passed down through the female line. Since the oldest archaeological site with a cat burial is about 9,500 years old, the geneticists suggest that the founders of the five lineages lived around this time and were the first cats to be domesticated.

Wheat, rye and barley had been domesticated in the Near East by 10,000 years ago, so it seems likely that the granaries of early Neolithic villages harbored mice and rats, and that the settlers welcomed the cats’ help in controlling them.

Unlike other domestic animals, which were tamed by people, cats probably domesticated themselves, which could account for the haughty independence of their descendants. “The cats were adapting themselves to a new environment, so the push for domestication came from the cat side, not the human side,” Dr. Driscoll said.

Cats are “indicators of human cultural adolescence,” he remarked, since they entered human experience as people were making the difficult transition from hunting and gathering, their way of life for millions of years, to settled communities.

Until recently the cat was commonly believed to have been domesticated in ancient Egypt, where it was a cult animal. But three years ago a group of French archaeologists led by Jean-Denis Vigne discovered the remains of an 8-month-old cat buried with its human owner at a Neolithic site in Cyprus. The Mediterranean island was settled by farmers from Turkey who brought their domesticated animals with them, presumably including cats, because there is no evidence of native wildcats in Cyprus.

The date of the burial far precedes Egyptian civilization. Together with the new genetic evidence, it places the domestication of the cat in a different context, the beginnings of agriculture in the Near East, and probably in the villages of the Fertile Crescent, the belt of land that stretches up through the countries of the eastern Mediterranean and down through what is now Iraq.

Dr. Stephen O’Brien, an expert on the genetics of the cat family and a co-author of the Science report, described the domestication of the cat as “the beginning of one of the major experiments in biological history” because the number of house cats in the world now exceeds half a billion while most of the 36 other species of cat, and many wildcats, are now threatened with extinction.

So a valuable outcome of the new study is the discovery of genetic markers in the DNA that distinguish native wildcats from the house cats and feral domestic cats with which they often interbreed. In Britain and other countries, true wildcats may be highly protected by law.

Female Shark Reproduced Without Male DNA

A hammerhead shark that gave birth in a Nebraska aquarium reproduced without mating, a genetic analysis shows.

This form of asexual reproduction, called parthenogenesis, has been found in other vertebrate species, including some snakes and lizards. But this is the first time it has been documented in a shark.

Researchers from the Guy Harvey Research Institute at Nova Southeastern University in Florida and Queen’s University Belfast in Northern Ireland found no male DNA in the female baby shark, which was born in December 2001 and died shortly after birth, apparently killed by another fish. The mother was one of three female bonnetheads, a small hammerhead species, that had been captured in Florida and kept without male sharks for three years in the Henry Doorly Zoo in Omaha.

At the time of the birth, many scientists thought that the female had mated with another species, or that it had used sperm obtained years before. Female sharks are capable of storing sperm, although none have been known to store it as long as these sharks had been isolated.

But through the analysis “it was pretty clear that there was no male contribution,” said Mahmood S. Shivji, director of the Guy Harvey Research Institute and author of a paper on the finding being published online today by the journal Biology Letters.

Instead, the female shark’s own genetic material combined during the process of cell division that produces an egg. A cell called the secondary oocyte, which contains half the female chromosomes and normally becomes the egg, fused with another cell called the secondary polar body, which contains the identical genetic material.

Robert E. Hueter, director of the Center for Shark Research at the Mote Marine Laboratory in Sarasota, Fla., said the finding helped fill a gap in understanding of parthenogenesis, which has been found to occur in most vertebrate lines except mammals and, until now, cartilaginous fishes like sharks.

Dr. Shivji said that after the bonnethead birth was reported, keepers at the Belle Isle Aquarium in Detroit reported similar virgin births by white spotted bamboo sharks. While those births have not been proved to result from parthenogenesis, Dr. Shivji said, it is reasonable to assume they did. And if it is found in these two species, “it seems not unreasonable to think this is probably more widespread in different shark lineages,” he said.

Gordon W. Schuett, an adjunct professor at Georgia State University who discovered parthenogenesis in a snake in 1997, said it would probably be discovered in more species “because we know to look for it.”

Previously, Dr. Schuett said, zookeepers and others tended to discount evidence of virgin births precisely because they were so out of the ordinary. But in recent years it has been found in Komodo dragons, other lizards and snake species.

Alcohol Is Tied to Lower Risk of One Type of Kidney Cancer

Scientists have discovered yet another reason that alcohol might be good for you. Using pooled data from 12 studies and more than 750,000 subjects, researchers found that moderate alcohol consumption — about a drink a day — is associated with a decreased risk of renal cell carcinoma, one type of kidney cancer.

The researchers found that people who drank two-tenths of an ounce to one-half an ounce of alcohol a day — beer, wine or liquor — reduced their risk of renal cell cancer by 18 percent, and those who drank a half-ounce or more reduced their risk by 28 percent. There is about a half-ounce of alcohol in 1 ½ ounces of hard liquor, 12 ounces of beer or a 5-ounce glass of wine.

The study had limitations in that it lacked a measure of alcohol use over time, depended on self-reports and had no information on family history of renal cell cancer.

Jung Eun Lee, the lead author and a fellow at Brigham and Women’s Hospital in Boston, would not encourage anyone to start drinking. Rather, she said, maintaining a healthy weight and avoiding smoking are essential as the “principal means to reduce renal cell cancer.”

Physical Activity Reduces Risk Of Hypertension In Young Adults

Young adults who spend more time participating in physical activity have a reduced risk of developing high blood pressure within the next 15 years, according to researchers at the University of Minnesota.

Research published in the April 2007 issue of the American Journal of Public Health found that young adults who exercised an average of five times a week and expended 300 calories per exercise session experienced a 17 percent reduction in the risk of developing hypertension.

In addition, study participants who maintained or increased their total time participating in physical activity from the start of the study to the finish decreased their risk of high blood pressure by 11 percent for every 1,500 calories they burned weekly.

"This study is the first of its kind to examine the link between physical activity and hypertension in young adults," said David Jacobs, Ph.D., study co-author and professor of epidemiology and community health at the University of Minnesota School of Public Health. "The study further confirms evidence that physical activity is related to hypertension."

Jacobs and colleague Emily Parker, lead author of the study and doctoral student at the University of Minnesota School of Public Health, analyzed data from the Coronary Artery Risk Development in Young Adults (CARDIA) study, which tracked physical activity and measured blood pressure levels in nearly 4,000 men and women over a 15-year period.

Overall, 634 adults developed cases of hypertension over the 15 years of follow-up. After adjusting for race, age, sex, education, and family history, data showed that those participants who were more physically active experienced a reduced risk for hypertension compared with those who were less physically active. "This study shows that physical activity should be considered in the prevention of hypertension in young adults," said Jacobs. "This link gives people another reason to increase their levels of exercise and remain physically active."

Source: University of Minnesota

Stress causes cancer development

U.S. medical scientists have discovered the stress hormone epinephrine makes prostate and breast cancer cells resistant to cell death.

Researchers at the Wake Forest University School of Medicine said they are the first to report that emotional stress might contribute to the development of cancer and might also reduce the effectiveness of cancer treatments.

The study, led by Dr. George Kulik, an assistant professor of cancer biology, was designed to determine whether there is a direct link between stress hormones and changes in cancer cells.

"Population studies have had contradictory results," said Kulik. "We asked the question: 'If stress is linked to cancer, what is the cellular mechanism?' There had been no evidence that stress directly changes cancer cells."

Kulik said the study's findings have several implications for patients and for researchers.

"It may be important for patients who have increased responses to stress to learn to manage the effects," said Kulik. "And, the results point to the possibility of developing an intervention to block the effects of epinephrine."

Scientists study social memory formation

A team of Canadian and French scientists has identified the internal part of the prefrontal cortex as key to memorizing social information.

Researchers from Canada's McGill University and France's University of Paris used a functional magnetic resonance imaging technique to measure cerebral activity in 17 volunteers while they accomplished a memory task involving pictures of social scenes (interacting individuals) and non-social scenes (landscapes with no people).

The researchers identified the medial prefrontal cortex as being the key structure in memorizing social information from a picture.

The scientists said that finding opens important perspectives regarding our understanding of the mechanisms of human recollections and mental disorders such as schizophrenia and autism that affect social and relational skills.

Holding Eye Contact Is Critical When Police Confront Hysterical Citizens

Holding eye contact, or “gaze,” with hysterical citizens is one of the most effective methods police officers can use to calm them down, according to new research conducted by the University of New Hampshire that relies on footage of the FOX TV show “COPS.”

The study by Mardi Kidwell, assistant professor of communication, “’Calm Down!’: the role of gaze in the interactional management of hysteria by the police,” was published recently in Discourse Studies.

According to Kidwell’s research, regulating gaze is central to face-to-face interaction. For police officers, it’s an important factor in gaining compliance from and calming hysterical citizens.

“A great deal of police work involves encountering people who are in crisis, people who are distraught, agitated and sometimes hysterical over the circumstances that have necessitated a police response. Moreover, as police departments nationwide transition from a more traditional model of policing, with its emphasis on catching law-breakers, to a model of community policing, with its emphasis on prevention, they have sought to adapt more humanistic, more dialogic approaches to their communications with citizens,” Kidwell says.

Kidwell’s research relies on police-citizen interactions obtained from the FOX TV show “COPS,” now in its 19th season. She used footage from “COPS” because most research on police-citizen interaction does not rely on a real-time, in-the-moment unfolding of events. In addition, police departments are reluctant to provide footage of their police-citizen interactions.

In the “COPS” segment discussed in the study, two police officers are trying to calm down a woman whose grandson has been shot. The six-minute segment shows the officers arriving on the scene of the shooting, inspecting the victim, questioning witnesses, discussing the case with other officers and, finally, seeking to calm the victim’s grandmother, who herself has been shot at.

The officers are forced to use increasingly stronger verbal tactics – called directives – to get the woman to look at them as they try to calm her down. The woman repeatedly looks at the officers and then looks away, and continues to be hysterical. Finally, one officer gently touches the woman’s face and turns it toward him, forcing her to look at him. Eventually, the officers are able to keep eye contact with her long enough so as to calm her down, help her regain a normal breathing pattern and compose herself so she can drive to the hospital to see her grandson.

Kidwell has found that officers treat citizens’ (usually suspects’) refusal to gaze at them as resistance, and they will continue to pursue the citizens’ gaze in order to gain compliance. “In situations of someone’s extreme distraught-ness, refusal to gaze is associated with being ‘out of it.’ In other words, with being unable to attend to, or participate in, in any normal or competent way current interactional activities,” she says.

Kidwell analyzed more than 35 hours off footage and hundreds of police-citizen interactions as part of her research. She found that police rely on holding gaze to calm individuals in a number of situations, including getting them to cooperate during questioning, keeping them from interfering with emergency workers, and gaining their compliance during arrests.

“There is another, perhaps less institutionally obvious responsibility that the officers are undertaking in this case. This is a responsibility that has to do with being a ‘helper,’ here, specifically with emotional work. This case and others that involve, for example, a small child whose parents have been arrested and a woman who has been abused by her husband, demonstrate that police responsibilities also include simply soothing people who are in crisis and trying to ameliorate their emotional suffering,” Kidwell says.

Source:University of New Hampshire

Futuristic Robot Adapts To People, New Places

In the futuristic cartoon series "The Jetsons," a robotic maid named Rosie whizzed around the Jetsons' home doing household chores--cleaning, cooking dinner and washing dishes.

Such a vision of robotic housekeeping is likely decades away from becoming reality. But at MIT, researchers are working on a very early version of such intelligent, robotic helpers--a humanoid called Domo who grasp objects and place them on shelves or counters.

A robot like Domo could help elderly or wheelchair-bound people with simple household tasks like putting away dishes. Other potential applications include agriculture, space travel and assisting workers on an assembly line, says Aaron Edsinger, an MIT postdoctoral associate who has been working on Domo for the last three years.

Edsinger describes Domo as the "next generation" of earlier robots built at MIT--Kismet, which was designed to interact with humans, and Cog, which could learn to manipulate unknown objects. Domo incorporates elements of both of those robots.

"The real potential of robots in the future is going to be realized when they can do many types of manual tasks," including those that require interaction with humans, Edsinger said. There are now plenty of robots doing manual work on factory assembly lines, but those machines follow a script and can't learn to adapt to new situations, as Domo can, said Rodney Brooks, director of MIT's Computer Science and Artificial Intelligence Laboratory.

"Robots in an automobile factory manipulate objects, but they do the same thing, along the same path, every time," Brooks said. "If robots are ever going to be truly useful, they need to be able to manipulate the objects we manipulate."

Living in the real world
Edsinger's team, overseen by Brooks, decided to focus on making a robot that can function in a real human environment--in someone's kitchen, for example. Robots that are designed to help people in their homes will have to be able to ignore the clutter found in most environments and focus only on certain stimuli, says Edsinger.

"Typically robots are placed in very restricted worlds because then you can control the environment. If you put a robot in someone's home, that approach just doesn't extend to that," he said. "We want the robot to adapt to the world, not the world to adapt to the robot."

Perched on a table in Edsinger's workspace, Domo can "see" everything going on in front of it. As the robot's large blue eyes roam across the room, cameras feed information to 12 computers that analyze the input and decide what to focus on.

Domo's visual system is attuned to unexpected motion, allowing it to focus on important stimuli within human environments. For example, locating human faces is critical for social interaction, and people are often in motion. When Domo spots motion that looks like a face, it locks its gaze onto it.

Edsinger recently demonstrated how Domo can interact with people to help them accomplish useful tasks.

Once he captures Domo's gaze, they exchange greetings. "Hey, Domo," Edsinger says, to which Domo responds, "Hey, Domo." "Shelf, Domo," says Edsinger, prompting the robot to find a shelf. Domo looks around until it spots a nearby table that looks promising. The robot reaches out its left hand to touch the shelf, much like a person groping for a light switch in the dark, to make sure the shelf is really there.

Once Domo has located the shelf, it reaches out its right hand towards Edsinger, who places a bag of coffee beans in the open hand. Domo wiggles them a little to get a feel for the object, then transfers the bag from its right hand to its left hand (nearest the shelf). Domo then reaches up and places the bag on the shelf.

Though it seems like a minor movement, wiggling the object is key to the robot's ability to accurately place it on a shelf, Edsinger says. Domo is programmed to learn about the size of an object by focusing on the tip of the object, for example, the cap of a water bottle. When the robot wiggles the tip back and forth, it can figure out how big the bottle is and decide how to transfer it from hand to hand or to place it on a shelf.

"You can hand it an object it's never seen before, and it can find the tip and start to control it," Edsinger said.

The human connection
The philosophy behind the team's approach is that humans and robots can work together to accomplish tasks that neither could do all alone.

"If you can offload some parts of the process and let the robot handle the manual skills, that is a nice synergistic relationship," Edsinger said. "The key is that it has to be more useful or valuable than the effort put into it."

For Domo or any robot to safely interact with humans, the robot has to be able to sense when a human is touching it. Domo has springs in its arms, hands and neck that can sense force and respond to it. If you grab its hand and push, the robot will move the way you want it to.

"By placing that spring in there, you get physical compliance that makes the whole body sort of springy, which makes it safer for human interaction," Edsinger said. But if you apply too much force or move Domo's arms in the wrong direction, it voices its displeasure by saying "ouch."

If robots are going to be useful in the home, it's also important for them to have a humanoid form, so people will feel more comfortable around them.

Such assistive robots could be very useful in finding solutions to the impending health care crisis caused by the aging of the baby boomers, Edsinger said. Having help with simple tasks, such as getting a glass from a cabinet, could make a big difference for elderly or wheelchair-bound people.

The original work on Domo was funded by NASA, and the project is now supported by Toyota, which is interested in developing partner robots for the home. Another application is in assembly line production. The idea is that intelligent robots could work together with people to make workers more productive and save manufacturing jobs from being sent overseas, says Edsinger.

Although a life of leisure enabled by robots who perform all manual labor is still securely in the realm of science fiction, Brooks says he can foresee a future where robots specialized for different functions help out with household chores.

"I don't think there's going to be one Rosie the robot doing everything in the home," said Brooks. "It's more likely to be a team of robots doing different things."

Source: Massachusetts Institute of Technology

School Bullying Affects Majority Of Elementary Students

Nine out of 10 elementary students have been bullied by their peers, according to a simple questionnaire developed by researchers at Lucile Packard Children's Hospital and the Stanford University School of Medicine. What's more, nearly six in 10 children surveyed in the preliminary study reported participating in some type of bullying themselves in the past year.

The survey explored two forms of bullying: direct, such as threatening physical harm, and indirect, such as excluding someone or spreading rumors. The researchers say the five-minute questionnaire is the first simple, reliable way for teachers and physicians to identify kids at risk and to measure the success of interventions aimed at reducing bullying in schools.

"We know that both bullies and victims tend to suffer higher levels of depression and other mental health problems throughout their lives," said child psychiatrist Tom Tarshis, MD, lead author of the study. "We need to change the perception that bullying at school is a part of life and that victims just need to toughen up."

Tarshis was completing a fellowship in child psychiatry and research at Packard Children's at the time he developed the questionnaire. He is currently the director of the Bay Area Children's Association. The research will be published in the April issue of the Journal of Developmental and Behavioral Pediatrics.

"When I first started to study this subject, there was no real questionnaire that had been tested," said Tarshis. "We couldn't take the next step until we had a tool that we knew worked."

Although the classic definition of bullying brings to mind fistfights in the schoolyard, other more subtle forms of torment also were surveyed. Tarshis recounted a girl in the ninth grade whose friends decided to stop speaking to her, spread nasty rumors about her and exclude her from activities, all right under the nose of an unsuspecting teacher.

"It was a little distressing how prevalent the problem is even in the middle- to upper-middle-class schools we surveyed," said Tarshis.

He and his co-author, Lynne Huffman, MD, associate professor of pediatrics and of psychiatry at the School of Medicine, surveyed 270 children in grades three through six in two schools in California and one in Arizona to determine if the 22-item questionnaire yielded statistically accurate results. Students were scored based on their responses - never, sometimes or often - to such statements as, "At recess I play by myself," "Other students ignore me on purpose," and "Other students leave me out of games on purpose."

Tarshis and Huffman then compared the results to those of other, more complicated surveys intended to identify bullies and victims. They also administered their survey twice to 175 of the students to determine if the results were consistent over time. They found that the responses were highly reliable, and the survey was easily understood and completed by even the youngest students in the sample.

"We found it particularly interesting that these indications of victimization and bullying are apparent at very young ages," said Huffman. "Our hope is that this questionnaire will be utilized by teachers, pediatricians and even child psychiatrists to identify those children needing early and direct intervention."

The stakes are high. Previous research has shown that, without intervention, bullying behavior persists over time: a child who is a bully in kindergarten is often a bully in elementary school, high school and beyond. Such behaviors are not without consequence, though. These career bullies are not only slightly more likely than their peers to serve prison time as adults, they also tend to suffer from depression.

Perhaps not surprisingly, kids who are routinely victimized exhibit higher levels of depression, anxiety and suicidal thoughts than do non-victims. Such statistics highlight the importance of being able to identify at-risk kids and assess the effectiveness of interventions.

Efforts to stop school bullying have been gathering steam for several years. Those most likely to be effective, according to Tarshis, promote an attitude change from the principal to the recess monitors to the parents. They range from presentations to entire schools to discussions with individual students about how to respond when they are bullied or when they see someone bullying another student.

"Positive peer pressure is an important component of effective intervention," said Tarshis. "When uninvolved students step up and let the perpetrator know that their behavior is not acceptable, it's a powerful message."

Source:Stanford University Medical Center

Music players can cause hearing loss

Portable music players can damage your hearing, recent research suggests. Many players can reach potentially damaging volumes, and many users may habitually be cranking the sound up that high.

In a study published in December 2004, Brian J. Fligor, Sc.D., and L. Clarke Cox, Ph.D., at Boston University measured the volume levels of six portable CD players, through both the original headsets, if any, and five others purchased separately. At their highest settings, most of the 35 possible player-headset combinations were loud enough to cause irreversible noise-induced hearing loss if used regularly for as little as a few minutes per day.

The measurements were done shortly before iPods became popular. Fligor, now director of diagnostic audiology at Children's Hospital Boston, said preliminary results indicate that the volumes produced by iPods and other MP3 players are "in the same ballpark" as that of the CD players.

In a separate study published in April 2005, Warwick Williams of Australia's National Acoustic Laboratories measured the noise emanating from the personal music players of 55 randomly chosen passers-by in two busy city intersections. The volume averaged about 86 decibels--a bit too high, say Consumer Reports' noise experts, for extended daily listening. Some players were turned up much higher than that.

At maximum volume with the included headphone, nearly all the MP3 players we rated exceeded 85 decibels in our tests at an external lab, and some exceeded 100, a level that can damage hearing even after short periods of time. To avoid hearing loss, our experts say you should never set your music player's volume higher than 85 decibels, about the same level as a vacuum cleaner or a noisy restaurant. Be sure to judge the volume conservatively: Music you like tends to sound softer than an annoying sound with the same decibel level.

Many players in our MP3 Ratings (available to subscribers) have built-in volume limiters that take the guesswork out of safe listening. Some models have a preset safety level, which can be activated via the player's menu or an on/off switch. All iPods and some Creative models allow you to custom-set the volume limit, as well as protect the setting with a pass code--a nice touch for concerned parents. We recommend setting the maximum volume between 1/2 and 3/4 of the volume bar's full setting. But be aware that the loudness of individual songs can vary significantly, depending upon genre, equalizer setting, and how the song was recorded.

people whose living and working environments are otherwise quiet can safely listen to 85-decibel music for several hours a day. But if you're regularly exposed to other loud sound--whether from machinery, transportation, or live music--you should wear hearing protection at those times if you want to enjoy music from your portable player at other times. That's because damage from noise exposure is cumulative. If you have any concerns about hearing loss, see an audiologist soon.