People Affected: Industrial
FARMERS:
A recently completed study indicates that, not only are farmers more likely than the average worker to have hearing loss, those with hearing loss are at greater risk for injury! Here's the press release from the American Institute of Physics (AIP).
Hearing loss puts farmers at higher risk for suffering an injury at work, according to a new University of Iowa study that will be released today at the National Hearing Conservation Association's 32nd annual conference.
A team led by Dr. Nancy Sprince of the University of Iowa College of Public Health had farmers perform self assessments of their hearing to assess a correlation between hearing loss in farmers and occupational injury.
The study's participants were pulled from the larger Agricultural Health Study that included 30,000 Iowa farmers. Of those, 7,000 were randomly selected to participate, and after a screening, 431 were chosen for the case group and 473 for the control group. The case group was made up of farmers who said they had been injured on the job in the past year, and the control group said they had not been.
They were asked whether they had difficulty hearing normal conversation even with a hearing aid. The farmers who had difficulty hearing normal conversation were shown to be 80 percent more likely to suffer an injury related to a fall on the farm. Wearing a hearing aid was shown to have the highest correlation to work-related injury. Hearing aid-wearers were 2.4 times as likely to be injured on the job, and they were 5.4 times more likely to suffer an animal-related injury, like falling off a horse, and 4.4 times more likely to suffer a machinery-related injury. Other risk factors found to be associated with greater injury include working 50 or more hours a week on a farm, having large livestock on the farm, and taking medication regularly.
This is important because farmers have been shown to be at a higher risk for hearing loss than other American workers. The loud conditions on farms created by tractors, combines, grain dryers, chainsaws, livestock and other things create a hazardous work environment that can lead to noise-induced hearing loss. Compounding the problem is that hearing protection is not always worn. Hearing aids help restore some of the farmers' auditory abilities, but the best situation is for them to retain as much of their natural hearing ability as possible.
Previous studies have established farms are dangerous work environments. A 2005 study found farmers are eight times more likely to suffer a fatal occupational injury than the average American worker and twice as likely to suffer a non-fatal occupational injury.
"In many cases it is difficult to engineer out noise on the farm, so farmers have to rely on personal protective equipment," Sprince said. "And too often they are unaware of the tasks that require hearing protection."
HEARING LOSS & HIGH-SPEED DENTAL TOOLS
After 36 years in private dental practice, Fred Kreutzer, D.M.D., began struggling to hear. It's been five years since he retired from his practice and Kreutzer now wears hearing aids in both ears. Although he has a family history of hearing loss, he believes the high-speed tools he worked with eight hours a day for so many years may have played a role in his hearing troubles. "I think if you listen to any high-pitched noise for any length of time, it will get to you eventually," said Kreutzer, an assistant professor in operative dentistry at the OHSU School of Dentistry (http://www.ohsu.edu/sod). "But in my case, with a family history of hearing loss, it may be hereditary, as well."
Whether high-speed dental tools contribute to long-term hearing loss is the subject of a study currently under way in the OHSU Tinnitus Clinic and the School of Dentistry. According to Robert Folmer, Ph.D., one of the study leaders, published research is mixed about whether high-speed dental tools contribute to noise-induced hearing loss over time.
"Over the years, we have seen dentists in the OHSU Tinnitus Clinic who were convinced that long-term exposure to sound from high-speed hand pieces contributed to their high-frequency hearing loss and tinnitus," said Folmer. "These anecdotes, in combination with the research being divided about high-speed hand pieces playing a role in hearing loss, prompted our study. We hope the study is a good first step toward scientific evidence behind the anecdotes we've been hearing." Fulmer is associate professor of otolaryngology/head and neck surgery, School of Medicine, and chief of clinical services at the OHSU Tinnitus Clinic, Oregon Hearing Research Center.
Tinnitus, or ringing of the ears, can be constant or intermittent and can include buzzing, hissing or sizzling sounds. Many people experience momentary tinnitus, a high-pitched tone that lasts up to 30 seconds. Acute tinnitus, however, can last days or weeks and is most commonly caused by exposure to loud noise such as music at a rock concert, power tools or gunfire. The subsequent ringing indicates damage to the tiny hair-like structures within the inner ear and if exposure to loud noise continues, permanent hearing loss is likely.
Most of the current high-speed hand pieces, such as high-speed drills and scalers used by dental professionals, are between 90 to 100 decibels, says Folmer. That's the equivalent of a gas lawnmower or other power tools, which are loud enough to cause hearing loss over time. And hand pieces have actually gotten "quieter" over the years with the advent of modern technologies. However, very few dental professionals or students interviewed for the study so far, wear earplugs to protect themselves from this noise.
None of the 54 dental schools nationally are known to require dental students to wear ear protection while treating patients.
School of Dentistry Dean Jack Clinton, D.M.D., welcomed Folmer's study. "Any research that can help us keep students healthy and safe is a top priority," said Clinton. "We hope just the fact that the study is being done will continue to help raise awareness within the dental school about the possible hearing loss from high-speed dental instruments so dental professionals can make good decisions as they go through their careers."
Folmer is conducting his research this summer with Clackamas High School senior April Kaelin, a student he is mentoring through Portland State University's Apprenticeships in Science and Engineering (ASE) program. Folmer and April are investigating noise-induced hearing loss by conducting hearing tests with a portable audiometer, examining ear canals with an otoscope and asking participants to answer questions about occupational and recreational noise exposure. They also have measured the sound levels of different hand pieces while they're used on patients.
"We want to compare the hearing tests of dentists, dental assistants, and dental hygienists to those of dental students and people of comparable age in other professions," said Folmer. "We also want to examine whether there's a correlation between hearing thresholds and the amount of time that dental professionals are exposed to loud devices at work. And if dental professionals exhibit evidence of noise-induced hearing loss, can it be correlated with occupational or recreational noise exposure? Our hypothesis is that if dental professionals utilize hearing protective devices, they will exhibit less noise-induced hearing loss than dental professionals who do not protect their ears."
Charles (Mark) Malloy, D.M.D., M.S., assistant professor of prosthodontics at the OHSU School of Dentistry, wore ear protection for most of his 21 years of dentistry in the military. "Hearing loss from high-speed hand pieces has been a suggestion in dentistry for as long as I can remember," said Malloy. "My dad was a dentist so I grew up around dentists and there were a lot of them that couldn't hear. It sounds reasonable to me that high-speed hand pieces may contribute to long-term hearing loss." Malloy said he stopped wearing ear protection a decade ago when he joined the School of Dentistry and began seeing patients only one day a week, but the study is making him consider using ear protection again. "Ears are pretty nice!" said Malloy, with a chuckle.
Rita Patterson, D.M.D., an assistant professor of prosthodontics who introduces the hand pieces to first-year students, also is interested in the study. "We tell the students that they can wear earplugs, which are supplied to students as a standard part of their dental equipment. There are times during the course that I teach that we have 75 high-speed hand pieces running at the same time [there are 75 dental students] for more than two hours at a time. Many instructors, including myself, wonder if we have had some hearing loss from the exposure."
SIRENS
There was a time when loud sirens on emergency vehicles were generally considered a good thing. But, in an age obsessed with risk assessment, it turns out they can be too noisy. The vehicles used by Scots firefighters and police officers have been given extra soundproofing after tests showed siren noise could cause hearing damage to crews. Grampian Fire and Rescue has spent £12,000 on sound-proofing its fire engines after health and safety experts found unacceptable levels of noise inside the cabs.
DOG HANDLERS:
A garda dog handler is suing the State for alleged hearing loss because of exposure to loud barking by dogs under his control.
Garda Thomas Donnelly has told the High Court that the dogs barked most of the time during routine daily patrols in garda transit vans around the city. Garda Donnelly said up to four dogs could be in the van with him at any one time and would either continuously bark at each other or at anybody near the van. He now wears hearing aids in both ears and since 2002 wears ear protectors at all times while on duty. Garda Donnelly said that the excessive barking by the dogs was inside the garda vans and not when working outside. He said the dogs would bark at each other and at people walking in front of and at the back of the van when stopped at traffic lights and pedestrian crossings. Garda Donnelly was assessed in 2001 on the instructions of the garda medical officer. The court was also told that a consultant, Dr McShane, said that the inner ear damage was caused by chronic noise exposure and was irreversible. Consultant Dr Blaney told the court that a number of factors including noise had contributed to Garda Donnelly's substantial hearing loss. He said his assessment indicated that the hearing loss was greater than normal in a 50-year-old but could not say whether noise was a big or small part of it.