noise & cardiovascular disease

Noise & Cardiovascular DiseaseCan hearing conservation programs prevent heart attacks too?

Hugh W Davies, PhD, CIHSchool of Environmental Health

NHCA Keynote, Feb 26th, Orlando, FL

2


3

Occupational risk factors for CVD


4

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:

5


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

6



7


8

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


9

Noise & Hypertension - Epidemiology


10

BC Sawmill Exposure levels (N=1,901)

Davies et al, Occup Environ Med. 2009; 66(6):388-94


11

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


12


13

Sawmill Cohort: Noise & Hypertension

Sbihi, et al., Occup Environ Med 2008;65:643–646


14

Sawmill Cohort: Noise & Hypertension


15

Noise & Hypertension - Review

Van Kempen, et al, 2002; Environ Health Perspectives 110(3): 307-17


16

Sawmill Cohort: Noise and Heart Disease

Davies et al., 2005, Epidemiology, 16:25-32


17

Sawmill Cohort: Noise and AMI


18

Sawmill Cohort: Noise and AMIReanalyzed excluding HPD users


19

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


20

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


21

So can Hearing Conservation Programsprevent Heart Attacks?


22

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


23

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…


24

Cumulative Exposure and AMI


25

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


26

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


27

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


28

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?


29

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


30

UBC Vancouver Noise Mapping


31

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


32

Acknowledgments Paul Demers, Murray Hodgson, Kay Teschke, Jean

Shoveller Hind Sbihi, Musarrat Nahid, Amber Louie WorksafeBC

Christine Harrison Heather Gillis


33


34

noise & cardiovascular disease

Documents

fl11 nhca keynote

fl67nhca keynote

fl8nhca keynote

noisedisturbed sleep

heart attacks

heart rate increase

fl3 occupational risk

fl12 sawmill cohort