Seis em cada dez portugueses vivem com níveis de ruído acima do recomendado

Segundo a Direcção Geral do Ambiente, mais de 60 por cento da população portuguesa vive com níveis de ruído acima do recomendado pela Organização Mundial de Saúde (mais de 55 decibéis), sendo que 19 por cento está mesmo exposta a barulho incomodativo (mais de 65 decides). A situação é mais crítica é nos grandes pólos urbanos, já que o tráfego rodoviário expõe diariamente cinco milhões de portugueses a tons excessivos e nocivos para a saúde.

A principal causa de perda auditiva nos jovens e adultos é o ruído. Esta situação é definitiva e, como tal, irreversível. O cenário não é animador, uma vez que, contrariamente a outros países da União Europeia, Portugal tem registado, nos últimos anos, um aumento dos níveis de ruído, especialmente nas grandes cidades, fazendo com que, no seu dia-a-dia, cinco milhões de portugueses se encontrem expostos a elevados níveis de ruído, quer devido à sua profissão, quer devido ao tráfego rodoviário. Para além de perda auditiva irreversível, a exposição prolongada ao ruído pode originar outros problemas de saúde, como psicológicos ou doenças cardiovasculares.

“A perda auditiva induzida por um trauma acústico é uma realidade que não deve ser ignorada. É a principal causa de perda auditiva irreversível. Todos nós estamos expostos diariamente a ruído excessivo, com consequências directas”, segundo refere em comunicado Pedro Paiva, audiologista.

A perda da audição pode ser causada por um problema mecânico no canal auditivo ou no ouvido médio que obstrói a condução do som (perda condutiva de audição) ou por uma lesão no ouvido interno, no nervo auditivo ou nas vias do nervo auditivo no cérebro (perda neuro-sensorial da audição). Os dois tipos de perda da audição podem ser diferenciados comparando como uma pessoa ouve os sons conduzidos pelo ar e como os ouve conduzidos pelo ossos.

A perda neuro-sensorial denomina-se sensorial quando afecta o ouvido interno, e neural quando afecta o nervo auditivo ou as vias do nervo auditivo localizadas no cérebro. A perda auditiva sensorial pode ser hereditária, ser provocada por ruídos muito intensos (trauma acústico), por uma infecção viral do ouvido interno, por certos fármacos ou pela doença de Ménière.

Evitar exposição a ruído intenso, não se automedicar, não introduzir objectos no ouvido, evitando também a tentativa de limpar o conduto auditivo são atitudes que podem evitar uma deficiência auditiva, tanto na infância e adolescência como na fase adulta.

Notícia acedida em Ciência Hoje

Persistent Workplace Noise More Than Doubles Risk of Heart Disease

A persistently noisy workplace more than doubles an employee's risk of serious heart disease, suggests research published online in Occupational and Environmental Medicine. Young male smokers seem to be particularly at risk,according to the study's findings.

The researchers base their findings on a nationally representative sample of more than 6,000 U.S. employees, aged 20 and up, who had been part of the US National Health and Nutrition Examination Survey (NHANES) between 1999 and 2004.

This study included detailed household interviews, addressing lifestyle and occupational health, medical examinations, and blood tests.

Participants were grouped into those who endured persistent loud noise at work, to the extent that it was difficult to talk at normal volume for at least three months, and those working in more comfortable surroundings.

One in five (21-percent) workers said they put up with a noisy workplace for an average of almost nine consecutive months. This group, whose average age is 40, also tended to smoke and weigh more than their peers working in quieter work environments, adding to the group's risk factors for heart disease.

Workers in persistently noisy workplaces were between two to three times as likely to have serious heart problems as their peers in quiet workplaces.

The association to heart disease was particularly strong among workers under 50, who made up more than 4,500 of the total sample. They were between three and four times as likely to have angina or coronary artery disease or to have had a heart attack.Blood tests of these workers did not indicate particularly high levels of cholesterol or inflammatory proteins, both of which are associated with heart disease. But diastolic blood pressure, which measures the pressure of the artery walls when the heart relaxes between heartbeats, was higher than normal, a condition known as isolated diastolic hypertension, or IDH. This is an independent predictor of serious heart problems.

The findings suggest that those employees regularly exposed to loud noise at work were twice as likely to have IDH.The authors speculate that loud noise day after day may be as strong an external stressor as sudden strong emotion or physical exertion, the effect of which is to prompt various chemical messengers to constrict blood flow through the coronary arteries.

Researchers conclude: "This study suggests that excess noise exposure in the workplace is an important occupational health issue and deserves special attention."

Info at AcoustiBlok

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Hearing loss in musicians - Is there a problem?

There are several unique reasons to be concerned about sound exposure and its effect on musicians’ hearing. First of all, musicians’ working hours are usually quite varied as compared to most employees, especially during performance weeks. Also, musicians spend a varied amount of time practicing, playing solo and as a member of different groups, and enjoying the music of others. One review article suggested that classical musicians play an average of 25 hours per week (Palin 1994), but this could vary widely from week to week, and from person to person.

Most people are aware that loud noises are bad for your ears, and might lead to hearing problems down the road. Since listening to music is a positive, pleasant, and desirable activity for many people, it may come as a surprise that music can have a negative effect on hearing too.

Work-related hearing loss is quite a different problem for those in the music industry than it is for industrial workers. Musicians and DJs regard themselves as having superior hearing, specially trained to detect nuance or tone, and consider that their hearing is their livelihood (Axelsson and Lindgren 1981; Early and Horstman 1996). A slight hearing loss that may not bother an industrial worker may cause difficulties for a musician. In addition, controlling musicians’ exposures poses a different challenge than it does for other types of employees.

Even though sound levels can be exceedingly high at music venues, very few investigations on the hearing of musicians had actually taken place as of the early 1980’s (Axelsson and Lindgren 1981). An early study on the hearing of orchestral musicians at an opera house found that 42% of participants had hearing loss that was greater than expected for their age (Axelsson and Lindgren 1981). Many other studies, including both classical and pop musicians, have found similar results: musicians have worse hearing than would be expected based on their age (Lebo and Oliphant 1968; Westmore and Eversden 1981; Jansson and Karlsson 1983; Hart, Geltman et al. 1987; Ostri, Eller et al. 1989; Royster, Royster et al. 1991; Fearn 1993; Jaroszewski and Rakowski 1994; Jaroszewski, Fidecki et al. 1998; Eaton and Gillis 2002; Kahari, Zachau et al. 2003).

Other researchers report no difference between musicians and other workers (Arnold and Miskolczy-Fodor 1960; Karlsson, Lundquist et al. 1983; Johnson, Sherman et al. 1985; McBride 1992; Kahari 2001); this difference in finding may be due to varying definitions of what constitutes hearing loss, difficulties in quantifying leisure noise exposure, or poor study quality (Sataloff 1991).

The general consensus in the literature suggests that hearing loss is a problem for musicians, and this varies across type of music played (i.e. – rock or jazz or classical),and type of instrument played (Palin 1994; Mikl 1995). It has been suggested that since sound pressure levels (SPL) produced by music can be (and often are) well above the recommended 85 dB, we have good reason to be concerned about musicians’ hearing.

Another complaint from some musicians (but more typically of industrial workers) is a disease called “tinnitus”, which is a permanent ringing in the ears caused by chronic exposure to loud noises (Axelsson and Ringdahl 1989; Axelsson and Prasher 2000; Lockwood, Salvi et al. 2001). More research needs to be done on the musician’s experience with this often highly debilitating disease.

Info accessed at ActSafe

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Can vitamins and minerals prevent hearing loss?

Noise is an enemy of hearing, and it really doesn't take a lot of noise to damage hearing. About 10 million people in the United States alone —from troops returning from war to students with music blasting through headphones— are suffering from impairing noise-induced hearing loss.

The rising trend is something that researchers and physicians at the University of Michigan Kresge Hearing Research Institute are hoping to reverse, with a cocktail of vitamins and the mineral magnesium that has shown promise as a possible way to prevent hearing loss caused by loud noises. The nutrients were successful in laboratory tests, and now researchers are testing whether humans will benefit as well.

"The prevention of noise induced hearing loss is key," says Glenn E. Green, M.D., assistant professor of otolaryngology at the U-M Health System and director of the U-M Children's Hearing Laboratory.

"When we can't prevent noise-induced hearing loss through screening programs and use of hearing protection, then we really need to come up with some way of protecting people who are still going to have noise exposure. My hope is that this medication will give people a richer, fuller life."

The combination of vitamins A, C and E, plus magnesium, is given in pill form to patients who are participating in the research. Developed at the U-M Kresge Hearing Research Institute, the medication, called AuraQuell, is designed to be taken before a person is exposed to loud noises. In earlier testing at U-M on guinea pigs, the combination of the four micronutrients blocked about 80 percent of the noise-induced hearing impairment. This is the first NIH-funded clinical trial involving the prevention of noise-induced hearing loss."

If we can even see 50 percent of the effectiveness in humans that we saw in our animal trials, we will have an effective treatment that will very significantly reduce noise-induced hearing impairment in humans. That would be a remarkable dream," says co-lead researcher Josef M. Miller, Ph.D., the Lynn and Ruth Townsend Professor of Communication Disorders and director of the Center for Hearing Disorders at the U-M Department of Otolaryngology's Kresge Hearing Research Institute. Miller is leading the research along with colleagues at Karolinska Institute, where Miller also has an appointment; the University of Florida; and the University Castille de La Mancha.

Info at ScienceDaily

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Researchers Urge Caution When Buying Noisy Toys

From Science Daily

While Road Rippers Lightning Rods, Let's Rock Elmo and the I Am T-Pain musical microphone might be sought-after gifts this holiday season, parents should ensure that their children don't risk permanent hearing damage by misusing them.

Researchers from UC Irvine's Department of Otolaryngology measured the noise levels of two dozen popular toys in stores and purchased the 10 loudest for precise gauging in a soundproof booth at UC Irvine Medical Center. They found that all exceeded 90 decibels and several reached 100 or more, equivalent to the noise of a chain saw, subway train or power mower.

"Generally, toys are safe if used properly," said Dr. Hamid Djalilian, associate professor of otolaryngology and director of neurotology and skull base surgery. "We tested the sound levels at the speaker and again at 12 inches, which is about the length of a toddler's arm."

But problems can arise if a noisy toy is held too close to the ears, he said: "Children are very sensitive to loud and high-pitched sounds. Unfortunately, hearing loss from noise damage is permanent and not currently curable."

According to the American Academy of Otolaryngology, unprotected exposure to sounds above 85 decibels for a prolonged period can lead to hearing impairment. Two factors contribute to this, Djalilian noted: loudness and duration. The louder a sound is, the less time it takes to cause hearing loss.

He suggested that someone buying a noisy toy for a child pay attention to the speaker's location -- under the item is often better than on top. Djalilian also recommended that an adult hold the toy as a youngster would and listen to its sound. "If it hurts your ears," he said, "then it's probably too loud for a child."

Toys tested / Decibel level at the speaker / Decibel level 12 inches from the speaker:

• Road Rippers Lightning Rods / 108 / 68
• I Am T-Pain microphone / 101 / 64
• Tonka Mighty Motorized Fire Truck / 100 / 69
• Marvel Super Shield Captain America / 98 / 69
• Whac-A-Mole game / 95 / 69
• Tapz electronic reflex game / 95 / 65
• Sesame Street Let's Rock Elmo / 95 / 74
• VTech Magical Learning Wand / 94 / 69
• Toy Story Buzz Lightyear Cosmic Blaster / 93 / 60
• Green Lantern Colossal Cannon / 92 / 67

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Exposure to Secondhand Smoke Associated With Hearing Loss in Adolescents

Exposure to secondhand smoke (SHS) is associated with increased risk of hearing loss among adolescents, according to a report in the July issue of Archives of Otolaryngology-Head and Neck Surgery, one of the JAMA/Archives journals.

Among U.S. children, approximately 60 percent are exposed to SHS, according to background information in the article. Studies have associated exposure to secondhand smoke prenatally or during childhood with various health conditions, from low birth weight and respiratory infections to behavioral problems and otitis media. Children exposed to SHS are more likely to develop recurrent otitis media, the authors note. "Secondhand smoke may also have the potential to have an impact on auditory development, leading to sensorineural hearing loss (SNHL)," they add.

Anil K. Lalwani, M.D., and colleagues from NYU Langone Medical Center in New York City examined the risk factors for SNHL, including SHS, among adolescents, stratified by demographic groups. They included 1,533 individuals from 12 years to 19 years of age who participated in the National Health and Nutrition Examination Survey from 2005 to 2006. Participants were interviewed about their health status and family medical history, exposure to SHS, and self-recognition of hearing impairment. In addition, they underwent a physical examination, including blood testing for cotinine (a by-product of nicotine exposure), and hearing tests.

Compared with teens who had no SHS exposure, those who were exposed to secondhand smoke exhibited higher rates of low- and high-frequency hearing loss. The rate of hearing loss appeared to be cumulative, increasing with the level of cotinine detected by blood tests. The results also demonstrated that more than 80 percent of participants with hearing loss did not realize they had impairment.

As hearing loss early in life can cause problems with development and functioning, the authors suggest that these results have "significant implications for public health." They note that most adolescents do not receive screening for hearing loss in the absence of risk factors; if further studies replicate these results, they state, SHS could be considered one such risk factor. "Adolescents who are exposed to SHS may need to be more closely monitored for hearing loss," the researchers conclude. "In addition, they should be educated about risk factors for hearing loss, such as recreational or occupational noise exposure and SHS."

Info at Science Daily

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Gene Therapy for Hearing Loss Moves a Step Closer

Boston — Researchers have found long-sought genes in the sensory hair cells of the inner ear that, when mutated, prevent sound waves from being converted to electric signals, a fundamental first step in hearing. The researchers then restored these electrical signals in the sensory cells of deaf mice by introducing normal genes.

The study paves the way for a test of gene therapy to reverse a type of deafness, to be conducted by US and Swiss collaborators. Findings appear in the November 21, 2011 online issue of the Journal of Clinical Investigation.

Sound waves produce the sensation of hearing by jiggling protruding hair-like structures on sensory hair cells in the inner ear. Scientists have long believed that the hair cells carry a protein that converts this mechanical motion into electrical signals. While similar proteins have been identified for other senses, taste, smell, sight, researchers had been unable to find the critical protein required for hearing, in part because of the difficulty of getting enough cells from the inner ear to study.

The research team is co-led by Jeffrey Holt, PhD, Department of Otolaryngology at Children's Hospital Boston, and Andrew Griffith, MD, PhD, of the NIH's National Institute on Deafness and Other Communication Disorders (NIDCD).

"People have been looking for more than 30 years," says Holt, also a member of the F.M. Kirby Neurobiology Center at Children's Hospital Boston. "Five or six possibilities have come up, but didn't pan out."

Holt, Griffith, and colleagues found that two related proteins, TMC1 and TMC2, are essential for hearing. They make up gateways known as ion channels, which sit atop the stereocilia and let electrically charged molecules (ions) move into the cell, generating an electrical signal that ultimately travels to the brain.

The gene for TMC1 was previously shown by Griffith and NIDCD-funded collaborators to be mutated in both mice and humans with hereditary deafness. TMC2, the new study found, seems to have a redundant function and may compensate if TMC1 is defective.

The study also found that the same defects affect sensory hair cells in the vestibular system, which underlies the sense of balance. Although TMC1 mutations cause only hearing loss, not balance problems, in humans, mice with defects in both TMC1 and TMC2 are deaf and fail balance tests requiring them to navigate a rotating rod.

The investigators then engineered an adenovirus to carry normal copies of TMC1 or TMC2 into the inner-ear hair cells of mice that had mutations in both genes. Using special techniques developed in Holt's lab, they recorded electrical responses to noise in the sensory hair cells when either TMC1 or TMC2 was added back, where before there had been none. "This is the first time anything like this has been done," says Holt.

But does restoring the electrical response translate into restoration of hearing? Holt and collaborators at the Ecole Polytechnique Federale de Lausanne (EPFL) in Switzerland recently received a $600,000 grant for a gene-therapy trial in mice. The researchers will deliver genes to the inner ear and measure whether electrical signals can be detected in the 8th cranial nerve and whether the animals respond to sound. EPFL will supply newer, safer gene-delivery vectors for testing that could potentially be developed for human trials.

According to the NIDCD, about one in 300 to 500 newborns are born deaf or hard-of-hearing, and it's believed that about half of cases have genetic causes. About 60 genes, including TMC1, are known to be associated with human deafness.

Yoshiyuki Kawashima, Gwenaelle S.G. Geleoc and Kiyoto Kurima were co-first authors. Holt, formerly at the University of Virginia, and Griffith were co-senior authors.

Source: Hearing Review

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