Researchers at the Canadian Federal Department of Health, in Ottawa, have undertaken a large cross-sectional study of national data from the Canadian Health Measures Survey to observe the effects of long-term occupational noise exposure on the body.
The survey included over 6,300 working Canadian adults, 1,700 of whom were employed in a noisy occupational setting for less than 10-years and 1,100 of whom were employed in an equivalent setting for more than 10-years.
Publishing findings in the Journal of the Acoustical Society of America,[i] earlier this month, the authors discuss that high-frequency sensorineural (noise-induced) hearing loss correlated with self-reported exposures (e.g. having to raise your voice to speak to someone at arm’s length), as expected, but did not support ‘the underlying theory that noise is a serious contributor to cardiovascular disease’.[ii]
Indeed, after adjusting for covariates [age, sex, and ethnicity, family history of illness, cigarette and alcohol consumption, fitness (exercise, diabetes and waist size), perceived stress and socioeconomic status], none of the associations found between loud noise exposure and changes in biomarkers for cardiovascular disease (CVD) or outcomes [such as hypertension (high blood pressure), myocardial infarction (heart attack), or stroke] remained statistically significant. Indeed, family history of CVD was a common feature among those reporting more than 10-years of exposure.[iii]
Even prior to adjustment, though, Canadians who had been most exposed to noise were ‘less than 10% more likely’ to suffer from CVD complications, compared to those who had never experienced a noisy workplace environment. Thus, in any event, the increase in risk of CVD brought on by exposure appeared to be ‘slight’.
Commenting on the outcomes of this investigation, Lead Author and Research Scientist, David Michaud, maintained that noise is ‘definitely capable of acting as a stressor and causing reactions in the body’, before going on to cite a ‘large science base’ connecting stress with CVD.
However, the question that remains is whether occupational noise can be ‘sufficient to cause stress-related illness’ at levels ‘below those known to impair hearing’.
For now, therefore, it is difficult to assess the degree to which a causal connection between noise and cardiovascular ill health could exist and this is reflected by contradictory discoveries in other works of academic literature.
In edition 227 of BC Disease News (here), for instance, we reported on a study conducted by the United States’ National Institute of Occupational Safety and Health (NIOSH), which found evidence of a statistically significant elevation in risk of hypertension and high cholesterol for workers with a history of noise exposure in the course of their employment (albeit there was no nexus for coronary heart disease or stroke).[iv]
More analysis of academic literature examining the link between high cholesterol and sensorineural hearing loss can be found in edition 38 (here).
[i] Michaud DS et al., Self-reported exposure to occupational noise and cardiovascular disease in Canada: Results from the Canadian Health Measures Survey. The Journal of the Acoustical Society of America. 150, 990 (2021)<https://asa.scitation.org/doi/pdf/10.1121/10.0005588> accessed 18 August 2021.
[ii] Examining Correlation Between Occupational Noise, Heart Disease’ (10 August 2021 American Institute of Physics) <https://publishing.aip.org/publications/latest-content/examining-correlation-between-occupational-noise-heart-disease/> accessed 18 August 2021.
[iii] Brian P Dunleavy, ‘Study: Noise, hearing loss at work have small effect on heart disease risk’ (10 August 2021 United Press International) <https://www.upi.com/Health_News/2021/08/10/hearing-loss-heart-disease-risk-study/4301628618210/> accessed 18 August 2021.
[iv] Kerns E et al., Cardiovascular conditions, hearing difficulty, and occupational noise exposure within US industries and occupations. Am J Ind Med. 2018 Jun; 61(6): 477–491. <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6897488/pdf/nihms-1045084.pdf> accessed 19 August 2021.