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[Application of ISO 1999:2013 (E) model in risk assessment of hearing loss caused by industrial noise]
1National Institute for Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Objective:
To assess the risk of hearing loss caused by industrial noise exposure of welders and assemblers in a mechanical equipment manufacturing enterprise, and to explore the practical application and possible underestimation of ISO 1999∶2013(E) model.
Methods:
A total of 829 noise-exposed male workers from a mechanical equipment manufacturing enterprise were selected as study subjects. The questionnaire survey was administered, and individual noise exposure level(L_(Aeq.8 h)) and hearing loss level were measured. The risk assessment method of ISO 1999∶2013(E) was used to calculate the change of hearing threshold level and the risk of noise-induced hearing loss. By comparing the median of permanent hearing threshold shift caused by actual noise with the median of ISO1999 predicted value, the reason of the difference between the predicted value of ISO 1999∶2013(E) model and the actual value was analyzed.
Results:
The L_(Aeq.8 h )was 89.5 dB(A), 77.4%(n=62)of the individual noise exposure levels exceeded 85 dB(A), and 24.6% of the participants(n=829) had different degrees of hearing loss. There was significant difference in hearing loss rate between welding and assembly positions(χ~2=10.07, P<0.01). The risk of noise-induced high-frequency hearing loss of 90% welders was 11.2% at the age of 50, and 14.0% at the age of 60. The risk of noise-induced deafness of 90% welders was 4.3% at the age of 60. The risk of high noise-induced frequency hearing loss of 90% assemblers was at the range of 4.0%-9.0% at the age of 40, 20.8% at the age of 50, and 22.5% at the age of 60. The risk of noise-induced deafness of 90% assemblers was at the range of 1.4%-6.4% at the age of 50, and 9.0% at the age of 60. Compared with actual median of permanent hearing threshold shift, ISO1999∶2013(E) predictions underestimated the median of permanent hearing threshold shift at 10.7 dB.
Conclusion:
The noise hazards of welding and assembly positions in mechanical equipment manufacturing enterprises are high relatively. ISO1999∶2013(E) can be used to predict the risk of noise-induced hearing loss in workers, but attention should be paid to the risk underestimation of this model.
