The effectiveness of applying different permissible exposure limits in preserving hearing threshold level among automobile industry workers: An intervention study
The aim of this study is to assess the effectiveness of applying different permissible exposure limits (90 in Factory 1 with 85 dBA in Factory 2) in preserving the hearing threshold and preventing the development of temporary Standard Threshold Shift (currently 90 dBA is adopted). The inclusion criterion is subjects who were exposed to levels above action level, either 85 or 80 dBA in Factory 1 and Factory 2, respectively. The exclusion criteria are those refused to participate, contract workers, workers suffering from diseases of ear, physical trauma to ear, lorry drivers (not stationed in the factories), workers who had undergone ear surgery and who were diagnosed to have congenital hearing loss. The study population is the general workers from the two factories in an automobile industry. The sample size required is 52 workers in each factory. Noise level was measured using a personal exposure noise dosimeter and a sound level meter. The hearing threshold levels were measured at baseline and then followed up at the first month (post-shift exposure) and again, on the sixth month. Data on hearing threshold levels were measured using a manual audiometer. Hearing protection devices with appropriate noise reduction rate were used to reduce noise exposure among participants (in Factory 1, the aim is between 85 and 90 dBA while in Factory is between 80 and 85 dBA). The primary outcome is to measure the mean hearing threshold levels, hearing threshold levels beyond 25 dBA and standard threshold shifts among participants between the two factories.
General information
Acronym
IRCT registration information
IRCT registration number:IRCT2013121515783N1
Registration date:2013-12-30, 1392/10/09
Registration timing:retrospective
Last update:
Update count:0
Registration date
2013-12-30, 1392/10/09
Registrant information
Name
Balachandar S. Sayapathi
Name of organization / entity
University of Malaya
Country
Malaysia
Phone
03-79674756
Email address
balach7777@siswa.um.edu.my
Recruitment status
Recruitment complete
Funding source
from University of Malaya
Expected recruitment start date
2012-02-01, 1390/11/12
Expected recruitment end date
2012-08-15, 1391/05/25
Actual recruitment start date
empty
Actual recruitment end date
empty
Trial completion date
empty
Scientific title
The effectiveness of applying different permissible exposure limits in preserving hearing threshold level among automobile industry workers: An intervention study
Public title
The effectiveness of exposure to different sound levels in preserving hearing
Purpose
Prevention
Inclusion/Exclusion criteria
Inclusion criterion is subjects exposed to noise levels above action level (85 dBA in one factory and 80 dBA in another factory).
Exclusion criteria are refused to participate, contract workers, who have diseases of ear, impacted wax, perforated tympanic membrane, physical trauma to ear, lorry drivers, who had undergone ear surgery and those have congenital hearing loss.
Age
No age limit
Gender
Both
Phase
N/A
Groups that have been masked
No information
Sample size
Target sample size:
104
Randomization (investigator's opinion)
Not randomized
Randomization description
Blinding (investigator's opinion)
Single blinded
Blinding description
Placebo
Used
Assignment
Parallel
Other design features
The statistician was also blinded except the researchers
Secondary Ids
empty
Ethics committees
1
Ethics committee
Name of ethics committee
Medical Ethics Committee, University Malaya Medical Centre
Street address
University of Malaya, Jalan Universiti
City
Kuala Lumpur
Postal code
50603
Approval date
2010-08-20, 1389/05/29
Ethics committee reference number
848.37
Health conditions studied
1
Description of health condition studied
Prevention of Noise-induced hearing loss
ICD-10 code
H83.3
ICD-10 code description
Noise-induced hearing loss
Primary outcomes
1
Description
Hearing threshold level
Timepoint
Six months
Method of measurement
Using manual audiometer
Secondary outcomes
1
Description
measuring knowledge, attitude and practice on noise-induced hearing loss
Timepoint
Six months
Method of measurement
Through questionnaire
Intervention groups
1
Description
Intervention (as control arm)- On Factory 1, Hearing protection devices were used to reduce noise exposure level between 85 and 90 dBA, based on noise reduction rate (currently adopted by the factory)
Category
Prevention
2
Description
Second arm (Intervention)- Hearing protection devices were used to reduce noise exposure level between 80 and 85 dBA
Category
Prevention
Recruitment centers
1
Recruitment center
Name of recruitment center
Toyota Auto Body (M) Sdn. Bhd.
Full name of responsible person
Haji Hamzah Suhadak
Street address
City
Shah Alam
Sponsors / Funding sources
1
Sponsor
Name of organization / entity
Post Graduate Research Grant University of Malaya
Full name of responsible person
Associate Prof. Dr. Moy Foong Ming
Street address
Department of Social and Preventive Medicine, Faculty of Medicine Building, University of Malaya
City
Kuala Lumpur
Grant name
Grant code / Reference number
PV106/2011A
Is the source of funding the same sponsor organization/entity?
Yes
Title of funding source
Post Graduate Research Grant University of Malaya
Proportion provided by this source
100
Public or private sector
empty
Domestic or foreign origin
empty
Category of foreign source of funding
empty
Country of origin
Type of organization providing the funding
empty
Person responsible for general inquiries
Contact
Name of organization / entity
University of Malaya
Full name of responsible person
Associate Prof. Dr. Tin Tin Su
Position
Assoc. Prof Department of Social and Preventive Medicine/ MBBS, MScCHHM, DrMed
Other areas of specialty/work
Street address
Department of Social and Preventive Medicine, Faculty of Medicine Building, University of Malaya, 50603 Kuala Lumpur
City
Kuala Lumpur
Province
Kuala Lumpur
Postal code
Phone
0060379674756
Fax
Email
tstin@ummc.edu.my
Web page address
Person responsible for scientific inquiries
Contact
Name of organization / entity
University Malaysia Sarawak, Malaysia
Full name of responsible person
Dr. Anselm Su Ting
Position
Lecturer in Department of Social and Preventive Medicine/ MBBS, MPH, MPH (OH), MFOM Ireland
Other areas of specialty/work
Street address
Department of Community Medicine and Public Health, Faculty of Medicine and Health Sciences, University Malaysia Sarawak,Kuching, Sarawak, Malaysia