Life is a blast, and not always in a good way. This was highlighted by a recent Herald on Sunday article, in which a reporter took noise readings at six Auckland venues and found the noise levels exceeded the 80dB health limit at half of them. The Imax theatre came in at 99dB, the Britomart Country Club at 95dB and a Les Mills gym class at 87dB. To put this in context, a pneumatic drill averages 100dB, a lawnmower 95dB and the sound of a lorry driving past around 90dB.
The point at which a sound becomes annoying is, of course, a matter of perception, and whereas most people would avoid the racket of a pneumatic drill, apparently sane people will voluntarily subject themselves to the high-volume din of a cinematic shoot-out. Even if you don’t mind such high volumes, they can still have a physiological impact. About 20-25% of the hearing-impaired population are thought to have noise-induced hearing loss.
If you find yourself asking people to repeat themselves all the time or you can’t hear what other people are saying in a crowded restaurant, you might be experiencing the early symptoms. Or you might be suffering from tinnitus, a distressing condition in which people hear phantom sounds generated by the brain to compensate for the loss of sound. This condition could be a result of problems in the middle ear, such as a blockage in the ear canal, perhaps caused by a build-up of earwax, an accumulation of fluid or an ear infection. If so, the problem can often be rectified.
Noise-induced hearing loss, however, is the result of damage to the delicate hair cells in the ear that respond to the different sound frequencies. When they are exposed to an intense sound for a short period, the cells get fatigued, which is why your ears might ring for a day or so after a loud concert. A sudden loud noise such as a gunshot or a jet taking off can cause immediate and irreversible damage. Continuous exposure (eight hours a day) to a noise over 85db can result in the cells gradually withering and dying.
Noise-induced hearing loss is more likely to be a hazard if you work in an industrial environment. According to University of Auckland professor of audiology Peter Thorne, large noisy industries are also most likely to be aware of noise regulations and take appropriate precautionary measures to protect workers. “The problems are in the smaller noisy industries where there is less awareness and less compliance.”
Those working in a small panel beater or engineering enterprise might be at risk, along with those working in pubs, clubs and shops with the stereo on full-blast all day. “Many hospitality and leisure areas where the noise levels are continuously at 75-85dB are potentially damaging to workers, especially those who are more susceptible. If the noise levels are there and people are exposed for long periods of time, they are at risk – whether they’re working in a foundry bashing metal or working in a shop.”
It has become much harder for people to successfully make an ACC claim for noise-induced hearing loss, says Thorne. The organisation has introduced a threshold for hearing loss (of 6%) and now requires any assessment to include age-related hearing loss. “Which is simplifying a very complex relationship. And 6% is a high threshold. You have to have a lot of damage before you reach that.”
Thorne believes that in the past 18 months, the number of ACC claims accepted for noise-induced hearing loss has fallen by about 60%. He says this drop in the number of accepted claims doesn’t mean fewer people are being affected but reflects the difficulty claimants have in obtaining a successful claim against such a high threshold.
Noise-induced hearing loss is still a common problem and he’d like to see ACC focus more on prevention. “We know that we can reduce the burden of hearing loss in this country by about 20-25% by reducing the amount of hearing loss from noise exposure. It’s a preventable condition. You just need to turn the noise down.”
A trip to Mars could increase your chances of developing Alzheimer’s disease, according to a study published in Plos One. Researchers from the University of Rochester exposed mice to the levels of radiation that would bombard astronauts on deep space missions, and found the rodents were far more likely to fail at certain memory tasks and that their brains showed signs of an abnormal accumulation of “plaque” associated with the disease.
BOWEL CANCER GENES
University of Oxford researchers who sequenced the DNA genomes of 20 people from families with a strong history of bowel cancer have strongly linked rare DNA faults in two genes to the disease. The study, published in Nature Genetics, found that everyone who had a faulty POLE or POLD1 gene developed bowel cancer or had a precancerous growth in the bowel. POLE and POLD1 are involved in processes that repair damage to DNA; when they don’t function properly, they are thought to lead to changes that cause bowel cancer.
Researchers at Ann Arbor have shown that using electricity to stimulate certain regions in the brain of patients with chronic, severe facial pain can prompt the body to release an opiate-like substance thought to be one of the body’s most powerful painkillers. Research had already found that delivering electricity through sensors on the skulls of chronic migraine patients can decrease the headache intensity and pain; this study explains how it is likely to work.