Citation

Lie A, Skogstad M, Johnsen TS, Engdahl B, Tambs K. BMJ Open 2014; 4(10): e005529.

Affiliation

Division of Mental Health, Norwegian Institute of Public Health, Oslo, Norway.

Copyright

(Copyright © 2014, BMJ Publishing Group)

DOI

10.1136/bmjopen-2014-005529

PMID

25324318

PMCID

PMC4202010

Abstract

OBJECTIVE: Railway workers performing maintenance work of trains and tracks could be at risk of developing noise-induced hearing loss, since they are exposed to noise levels of 75-90 dB(A) with peak exposures of 130-140 dB(C). The objective was to make a risk assessment by comparing the hearing thresholds among train and track maintenance workers with a reference group not exposed to noise and reference values from the ISO 1999.

DESIGN: Cross-sectional. SETTING: A major Norwegian railway company. PARTICIPANTS: 1897 and 2730 male train and track maintenance workers, respectively, all exposed to noise, and 2872 male railway traffic controllers and office workers not exposed to noise. OUTCOME MEASURES: The primary outcome was the hearing threshold (pure tone audiometry, frequencies from 0.5 to 8 kHz), and the secondary outcome was the prevalence of audiometric notches (Coles notch) of the most recent audiogram.

RESULTS: Train and track maintenance workers aged 45 years or older had a small mean hearing loss in the 3-6 kHz area of 3-5 dB. The hearing loss was less among workers younger than 45 years. Audiometric notches were slightly more prevalent among the noise exposed (59-64%) group compared with controls (49%) for all age groups. They may therefore be a sensitive measure in disclosing an early hearing loss at a group level.

CONCLUSIONS: Train and track maintenance workers aged 45 years or older, on average, have a slightly greater hearing loss and more audiometric notches compared with reference groups not exposed to noise. Younger (<45 years) workers have hearing thresholds comparable to the controls.

Language: en