Noise & Cardiovascular Disease
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Transcript of Noise & Cardiovascular Disease
Noise & Cardiovascular DiseaseCan hearing conservation programs prevent heart attacks too?
Hugh W Davies, PhD, CIHSchool of Environmental Health
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Occupational risk factors for CVD
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Noise and Heart Disease?
Neural activation
•Intensity•Frequency•Dynamics
Sound Perception
Noise Perception
Situational factors:• Communications• Concentration
Individual factors:• Coping potential• Noise sensibility
Disturbed activities, annoyance,
STRESS
“Direct”pathway
“Indirect”pathway
Appraisal
Sound Exposure
Modifying factors:
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Defense Reaction
Defeat Reaction
Increased ACTHIncreased Cortisol
Visceral Fat AccumulationInsulin resistance
Increased BP
Disease: Hypertension, Atherosclerosis, Myocardial Infarction,
Stroke, Cardiac Arrhythmias
Stress Response
Sympathetic adrenal medullary system
Sympathetic Nervous system activationElevated catecholamine levels
Increased heart rate, blood pressure
Hypothalamo-pituitary adrenal system
Structural autoregulation - up-regulating BP
Chronic or repeated
stimulation
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Habituation? Don’t you just “get used to it”?
Response rapidly extinguished with repetition in lab However, response elicited by superimposing a new
tone Response more resilient if source unpredictable,
variable Griefan et al, 2008
Noise-disturbed sleep: Simulated traffic episodes 45-77 dBA over 32 dbA
background Awakenings subside, but heart rate increase does not
extinguish
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Noise & Hypertension - Epidemiology
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BC Sawmill Exposure levels (N=1,901)
Davies et al, Occup Environ Med. 2009; 66(6):388-94
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BC Sawmill Cohort 27,000 blue collar male workers Employed at least one year, 1950-1995 at 14 BC Mills
Full sawmill employment histories Retrospective Exposure Assessment
Modeled based on 1900+ full shift dosimetry measurements
Outcomes: Hypertension Acute myocardial infarction Ischemic heart disease Stroke
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Sawmill Cohort: Noise & Hypertension
Sbihi, et al., Occup Environ Med 2008;65:643–646
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Sawmill Cohort: Noise & Hypertension
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Noise & Hypertension - Review
Van Kempen, et al, 2002; Environ Health Perspectives 110(3): 307-17
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Sawmill Cohort: Noise and Heart Disease
Davies et al., 2005, Epidemiology, 16:25-32
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Sawmill Cohort: Noise and AMI
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Sawmill Cohort: Noise and AMIReanalyzed excluding HPD users
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Heart disease - Summary Other occupational studies
McNamee et al 2006, Virkkunen et al 2005 Gan et al, unpublished
Hypertension, Acute myocardial infarction, IHD, associated with noise exposure Not stroke Effect for AMI greatest while employed
Reversible effect? Or noise acts as a “trigger”
Effect levels 85 dBA; not able to test below this “Burden of disease”: 20% of AMI deaths attributed to noise
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Gan et al,. unpublished NHANES 1999-2004, 6307 participants Self-reported noise exposure (~85 dB or over) Outcomes:
S/R of diagnosis of cardiovascular disease Blood pressure monitoring
Results 2-3 fold risk for angina, AMI, all types of CHD, isolated
diastolic hypertension (<140/>90) Higher risk in workers under 50 years
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So can Hearing Conservation Programsprevent Heart Attacks?
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Engineered/administrative Controls Reduction of noise levels below “threshold” would negate
risk What is threshold?
Workplace Our data suggest ~ 85 dBA Community noise – 60 dBA Chang - 85 dB threshold for sustained effects (24hr BP monitoring)
Noise control implementation weak Weak enforcement Lack of knowledge Over-reliance on HPD
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Hearing protection devices Our results show HPD an “effect modifier” Want to repeat our analyses adjusting for HPD
Exposure work done (Sbihi et al, 2010a,b, Ann Occup Hyg, in press)
Studies overestimating exposure Hypothesis: correction should “strengthen” dose-response curve
Melamed & Bruhis (1996): Reduced stress markers correlated HPD use at 85 dBA +
But: Melamed showed increased stress with HPD use in noise-annoyed Other parameters? Impulsive nature? Predictability? Frequency? And don’t know threshold…
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Cumulative Exposure and AMI
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Education Potentially, but would require new
materials/curriculum? Problems with education (Nahid et al,
unpublished) Food & Beverage workers Only training provided associated with annual
audiometry But
80 % knew stress associated with noise 48 %knew hypertension associated with noise
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Other aspects of HCP Noise Measurement
Identify hazardous areas Same problem with threshold though
Audiometry No – except as motivator to reduce noise exposure
Program Evaluation Not currently reflecting the CVD hazard
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To Summarize… Noise and heart disease appear linked
Biological plausibility, dose response, experimental evidence
Acute MI, hypertension But a lot we don’t know:
Effect levels – why are occupational and environmental effect levels so different?
Pathological mechanism Interactions (shift work, other stressors)
HCP probably do reduce the impact of noise on heart health Noise-reduction, HPD, education
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Other non-auditory effects Psychosocial
Annoyance Learning Other psychiatric disorders
Sleep Disturbance Stress-related
Hypertension Ischemic Heart Disease
Other Accidents Immune system Effects on the fetus Dementia?
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The Future Need to learn more about noise and CVD
Effect levels Mechanism of effect Interactions
UBC Vancouver traffic noise/air pollution study CVD Health in 400,000 adults Proposed: development effects in children
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UBC Vancouver Noise Mapping
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The Future – HCP’s and Heart Health Emphasize noise reduction
Widest benefits Programmatic implementation of HCP’s Targeted education
Heart health, noise and stress Noise reduction
Publicize exposure data popdataBC exposure database
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Acknowledgments Paul Demers, Murray Hodgson, Kay Teschke, Jean
Shoveller Hind Sbihi, Musarrat Nahid, Amber Louie WorksafeBC
Christine Harrison Heather Gillis
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