Ambient and at-the-ear occupational noise exposure and serum lipid levels.
OBJECTIVE
Occupational and residential noise exposure has been related to increased risk of cardiovascular disease. Alteration of serum lipid levels has been proposed as a possible causal pathway. The objective of this study was to investigate the relation between ambient and at-the-ear occupational noise exposure and serum levels of total cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, and triglycerides when accounting for well-established predictors of lipid levels.


METHODS
This cross-sectional study included 424 industrial workers and 84 financial workers to obtain contrast in noise exposure levels. They provided a serum sample and wore portable dosimeters that every 5-s recorded ambient noise exposure levels during a 24-h period. We extracted measurements obtained during work and calculated the full-shift mean ambient noise level. For 331 workers who kept a diary on the use of a hearing protection device (HPD), we subtracted 10 dB from every noise recording obtained during HPD use and estimated the mean full-shift noise exposure level at the ear.


RESULTS
Mean ambient noise level was 79.9 dB (A) [range 55.0-98.9] and the mean estimated level at the ear 77.8 dB (A) [range 55.0-94.2]. Ambient and at-the-ear noise levels were strongly associated with increasing levels of triglycerides, cholesterol-HDL ratio, and decreasing levels of HDL-cholesterol, but only in unadjusted analyses that did not account for HPD use and other risk factors.


CONCLUSIONS
No associations between ambient or at-the-ear occupational noise exposure and serum lipid levels were observed. This indicates that a causal pathway between occupational and residential noise exposure and cardiovascular disease does not include alteration of lipid levels.
Department of Occupational Medicine, Danish Ramazzini Centre, Aarhus University Hospital, Nørrebrogade 44 Building 2C, 8000, Aarhus C, Denmark. maiarlie@rm.dk.
Mai C
MC
Arlien-Søborg
Department of Occupational Medicine, Danish Ramazzini Centre, Aarhus University Hospital, Nørrebrogade 44 Building 2C, 8000, Aarhus C, Denmark. astrid_ss@hotmail.com.
Astrid S
AS
Schmedes
Department of Occupational Medicine, Danish Ramazzini Centre, Aarhus University Hospital, Nørrebrogade 44 Building 2C, 8000, Aarhus C, Denmark.
Z A
ZA
Stokholm
Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
M B
MB
Grynderup
Department of Occupational and Environmental Medicine, Bispebjerg University Hospital, Copenhagen, Denmark.
J P
JP
Bonde
Department of Occupational Medicine, Danish Ramazzini Centre, Aarhus University Hospital, Nørrebrogade 44 Building 2C, 8000, Aarhus C, Denmark.
C S
CS
Jensen
Department of Public Health, University of Copenhagen, Copenhagen, Denmark.|National Research Centre for the Working Environment, Copenhagen, Denmark.
Å M
ÅM
Hansen
Department of Occupational Medicine, Danish Ramazzini Centre, Aarhus University Hospital, Nørrebrogade 44 Building 2C, 8000, Aarhus C, Denmark.
T W
TW
Frederiksen
National Research Centre for the Working Environment, Copenhagen, Denmark.
J
J
Kristiansen
National Research Centre for the Working Environment, Copenhagen, Denmark.|Department of Cardiology B, Aarhus University Hospital, Aarhus, Denmark.
K L
KL
Christensen
Department of Occupational Medicine, Danish Ramazzini Centre, Aarhus University Hospital, Nørrebrogade 44 Building 2C, 8000, Aarhus C, Denmark.
J M
JM
Vestergaard
National Research Centre for the Working Environment, Copenhagen, Denmark.
S P
SP
Lund
Department of Occupational Medicine, Danish Ramazzini Centre, Aarhus University Hospital, Nørrebrogade 44 Building 2C, 8000, Aarhus C, Denmark.
H A
HA
Kolstad
D000328:Adult; D002318:Cardiovascular Diseases / Q000209:etiology; D002784:Cholesterol / Q000097:blood; D003430:Cross-Sectional Studies; D003718:Denmark; D004784:Environmental Monitoring / Q000379:methods; D005260:Female; D006801:Humans; D008055:Lipids / Q000097:blood*; D008075:Lipoproteins, HDL / Q000097:blood; D008077:Lipoproteins, LDL / Q000097:blood; D008297:Male; D066192:Manufacturing Industry; D008875:Middle Aged; D009623:Noise, Occupational / Q000009:adverse effects*; D009784:Occupational Diseases / Q000209:etiology; D016273:Occupational Exposure / Q000009:adverse effects* / Q000032:analysis; D012307:Risk Factors; D014280:Triglycerides / Q000097:blood
D008055:Lipids; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D014280:Triglycerides; D002784:Cholesterol
Cardiovascular disease; Causal pathways; Hearing protective devices; Manufacturing industries