Exposure to dangerously loud machinery makes farmers second only to construction workers in occupational hearing loss, a U.S. researcher says. Marjorie McCullagh, associate professor at University of Michigan School of Nursing, said her research project, HEAR on the Farm, said farmers are extremely vulnerable because the Occupational Safety and Health Administration doesn\'t regulate noise exposure on farms. Scientific findings regarding the prevalence of hearing loss among the estimated 1.3 million U.S. farmers varied greatly, with numbers ranging from 17 percent to 72 percent. Noise-induced hearing loss is particularly devastating because it\'s irreversible, and hearing aids and surgery don\'t help, McCullagh said. The majority of farmers don\'t wear hearing protection but do want to learn more about it, McCullagh said. The fact that 90 percent of farmers enrolled in her study were still participating supports this, especially when researchers consider retention rates of 30 percent to 50 percent highly successful. \"There are no systems in place to help them,\" McCullagh said in a statement. \"The farmers are expected to do that on their own.\" McCullagh and Michael Cohen, clinical research coordinator, traveled separately to different parts of the country to recruit participants. Bruce Breuninger, a fourth-generation farmer in Dexter, Mich., and one of 500 study participants nationwide, said he\'s worn hearing protection -- only intermittently -- but does suffer some hearing loss. \"I probably didn\'t wear it as religiously as I do now,\" said Breuninger, whose 80-year-old father, also a farmer, suffers profound hearing loss.