RESUMO
Objective To evaluate the risk of occupational noise-induced hearing loss in workers in a metal tool manufacturing enterprise, and to carry out risk classification and risk management. Methods A total of 91 male noise-exposed workers from a metal tool manufacturing enterprise in Hebei Province were selected as the research subjects using the convenience sampling method. The work site survey on occupational health and the measurement on individual noise exposure level were carried out. The ISO 1999：2013 (E) Acoustics-Estimation of Noise-Induced Hearing Loss was used to predict the risk of high frequency hearing loss (HFHL) and occupational noise-induced deafness (ONID). The risk classification and risk management were conducted using the WS/T 754-2016 Guideline for Risk Management of Occupational Noise Hazard (hereinafter referred to as WS/T 754-2016). Results The individual noise exposure intensity of workers in the six work sites of the enterprise, including blade workers, sheet punching workers, roller forging workers (hoe), hole punching workers, roller forging workers(shovels), and carpenters, exceeded the national occupational exposure limit, with the maximum volume of 91.2-104.1 dB(A). Among these workers, the positions of blade workers, sheet punching workers, and roller forging workers (hoe) were identified as critical control points for noise hazards in the enterprise. The detection rates of HFHL and ONID were 24.2% and 8.8%, respectively. The risk prediction results showed that, based on the actual noise exposure time and age of the study subjects, the risk of HFHL and ONID ranged from 1.7%-48.8% and 0.0%-29.5%, respectively. The risks of HFHL caused solely by occupational noise exposure when working up to 50.0, 55.0, and 60.0 years of age were 11.4% to 64.7%, 16.4% to 65.1%, and 17.2% to 59.4%, respectively. The risks of ONID caused solely by occupational noise exposure were 0.0% to 45.5%, 4.2% to 51.7%, and 5.9% to 57.4%, respectively. Except for the blade workers, the predicted median of potential noise-induced permanent threshold shifts (NIPTS) in the other five positions were lower than the actual values of NIPTS, with the difference ranging from 3.0-28.3 dB, and 73.3% of them underestimated by 10.0 dB or more. Conclusion The outcome of noise exposure on the hearing of workers in this enterprise are severe. Risk management should be conducted according to the WS/T 755-2016.