The results of this study suggest that market mill workers
have signifi cantly more sensorineural hearing loss when
compared to controls. This pattern of sensorineural hearing
loss, coupled with the signifi cant presence of 4 kHz
audiometric notch among the mill workers strengthened our
assertion that the hearing loss of the mill workers was likely
to be attributable to NIHL. Our study noted that only 5% of
mill workers used hearing protection devices, despite more
than half (54.5%) of these workers having some knowledge
of the harmful effects of noise on hearing.
The fi ndings from this study are similar to observations
of other researchers[17] who have noted that possessing
knowledge of the detrimental effect of noise on hearing
does not automatically translate into regular use of hearing
protective devices.
Our study demonstrated that market mill workers were
exposed to environmental noise levels ranging from 85.9
to 110.8 dBA which far exceeds the permissible levels of
85 dBA. The level of noise in this unregulated industry is
likely to have contributed to signifi cant sensorineural hearing
impairment of mill workers (P = 0.001). Our fi ndings suggest
a prevalence of possible NIHL of 25% in the better hearing
ear for the mill workers, which is lower than the prevalence
of 83% reported by Osibogun et al.[18] in a study in the
textile industry. Such differences may refl ect variation in
factors including the sources and levels of noise exposure,
duration of work in the industry and other exposure and
socio-demographic factors.
Importantly, self-reported hearing loss under-represented
rates of actual hearing loss on audiometric testing, indicating
that individuals may not accurately recognize hearing loss.
Further examination of this issue, particularly on levels at
which self-reported hearing loss appeared to become more
consistent, would be a useful adjunct to this research.
These fi ndings are consistent with the observation of other
researchers.[19] who confi rmed a poor relationship between
perceived and actual hearing loss in noise exposed workers
and suggest that the best practice requires inclusion of
audiometric screening as part of a complete hearing loss
prevention program.
Lack of government regulation on issues of occupational
hearing protection for market mill workers may at least in
part contribute to the high prevalence of occupational hearing
loss.
This study now provides a baseline from which preventive
measures can be initiated within small scale industries.
Collective efforts at prevention should include advocacy for
regulation of work practices within small scale enterprises
such as market mills. Regulation, coupled with comprehensive
health education and hearing conservation programs should
contribute to necessary impacts in reducing the prevalence of
NIHL in this sector.
Our study population was predominantly male, attributable
to the local socio-culture practice of having men operate high