Reinvigorating engineered noise controls: a systems approach.

OBJECTIVES: Hearing loss is a major worldwide health issue affecting an estimated 1.5 billion people. Causes of hearing loss include genetics, chemicals, medications, lifestyle habits such as smoking, and noise. Noise is probably the largest contributing factor for hearing loss. Noise arises from the workplace, ambient environment, and leisure activities. The easiest noise sources to control are workplace and environmental. Workplace noise is unique in that the employer is responsible for the noise and the worker. Also, workers may be exposed to much higher levels of noise than they would accept elsewhere. Employers follow the traditional hierarchy of controls (substitution/engineering, administrative, personal protective equipment [PPE]). Substituting or engineering a lower noise level actually reduces the hazard present to the worker but demand more capital investment. Administrative and PPE controls can be effective, but enforcement and motivation are essential to reducing risk and there is still some hearing loss for a portion of the workers. The challenge is to estimate the costs more clearly for managers. A systems engineering approach can help visualize factors affecting hearing health. MATERIAL AND METHODS: In this study, a systems engineering causal loop diagram (CLD) was developed to aid in understanding factors and their interrelationships. The CLD was then modeled in VenSim. The model was informed from the authors' expertise in hearing health and exposure science. Also, a case study was used to test the model. The model can be used to inform decision-makers of holistic costs for noise control options, with potentially better hearing health outcomes for workers. RESULTS: The CLD and cost model demonstrated a 4.3 year payback period for the engineered noise control in the case study. CONCLUSIONS: Systems thinking using a CLD and cost model for occupational hearing health controls can aid organizational managers in applying resources to control risk. Int J Occup Med Environ Health. 2023;36(5):672-84.

The effect of occupational exposure to noise on ischaemic heart disease, stroke and hypertension: A systematic review and meta-analysis from the WHO/ILO Joint Estimates of the Work-Related Burden of Disease and Injury.

BACKGROUND: The World Health Organization (WHO) and the International Labour Organization (ILO) are developing joint estimates of the work-related burden of disease and injury (WHO/ILO Joint Estimates), with contributions from a large number of individual experts. Evidence from mechanistic data suggests that occupational exposure to noise may cause cardiovascular disease (CVD). In this paper, we present a systematic review and meta-analysis of parameters for estimating the number of deaths and disability-adjusted life years from CVD that are attributable to occupational exposure to noise, for the development of the WHO/ILO Joint Estimates. OBJECTIVES: We aimed to systematically review and meta-analyse estimates of the effect of any (high) occupational exposure to noise (≥85 dBA), compared with no (low) occupational exposure to noise (<85 dBA), on the prevalence, incidence and mortality of ischaemic heart disease (IHD), stroke, and hypertension. DATA SOURCES: A protocol was developed and published, applying the Navigation Guide as an organizing systematic review framework where feasible. We searched electronic academic databases for potentially relevant records from published and unpublished studies up to 1 April 2019, including International Trials Register, Ovid MEDLINE, PubMed, Embase, Lilacs, Scopus, Web of Science, and CISDOC. The MEDLINE and Pubmed searches were updated on 31 January 2020. We also searched grey literature databases, Internet search engines and organizational websites; hand-searched reference lists of previous systematic reviews and included study records; and consulted additional experts. STUDY ELIGIBILITY AND CRITERIA: We included working-age (≥15 years) workers in the formal and informal economy in any WHO and/or ILO Member State but excluded children (<15 years) and unpaid domestic workers. We included randomized controlled trials, cohort studies, case-control studies and other non-randomized intervention studies with an estimate of the effect of any occupational exposure to noise on CVD prevalence, incidence or mortality, compared with the theoretical minimum risk exposure level (<85 dBA). STUDY APPRAISAL AND SYNTHESIS METHODS: At least two review authors independently screened titles and abstracts against the eligibility criteria at a first stage and full texts of potentially eligible records at a second stage, followed by extraction of data from qualifying studies. We prioritized evidence from cohort studies and combined relative risk estimates using random-effect meta-analysis. To assess the robustness of findings, we conducted sensitivity analyses (leave-one-out meta-analysis and used as alternative fixed effects and inverse-variance heterogeneity estimators). At least two review authors assessed the risk of bias, quality of evidence and strength of evidence, using Navigation Guide tools and approaches adapted to this project. RESULTS: Seventeen studies (11 cohort studies, six case-control studies) met the inclusion criteria, comprising a total of 534,688 participants (39,947 or 7.47% females) in 11 countries in three WHO regions (the Americas, Europe, and the Western Pacific). The exposure was generally assessed with dosimetry, sound level meter and/or official or company records. The outcome was most commonly assessed using health records. We are very uncertain (low quality of evidence) about the effect of occupational exposure to noise (≥85 dBA), compared with no occupational exposure to noise (<85 dBA), on: having IHD (0 studies); acquiring IHD (relative risk (RR) 1.29, 95% confidence interval (95% CI) 1.15 to 1.43, two studies, 11,758 participants, I2 0%); dying from IHD (RR 1.03, 95% CI 0.93-1.14, four studies, 198,926 participants, I2 26%); having stroke (0 studies); acquiring stroke (RR 1.11, 95% CI 0.82-1.65, two studies, 170,000 participants, I2 0%); dying from stroke (RR 1.02, 95% CI 0.93-1.12, three studies, 195,539 participants, I2 0%); having hypertension (0 studies); acquiring hypertension (RR 1.07, 95% CI 0.90-1.28, three studies, four estimates, 147,820 participants, I2 52%); and dying from hypertension (0 studies). Data for subgroup analyses were missing. Sensitivity analyses supported the main analyses. CONCLUSIONS: For acquiring IHD, we judged the existing body of evidence from human data to provide "limited evidence of harmfulness"; a positive relationship is observed between exposure and outcome where chance, bias, and confounding cannot be ruled out with reasonable confidence. For all other included outcomes, the bodies of evidence were judged as "inadequate evidence of harmfulness". Producing estimates for the burden of CVD attributable to occupational exposure to noise appears to not be evidence-based at this time. PROTOCOL IDENTIFIER: 10.1016/j.envint.2018.09.040. PROSPERO REGISTRATION NUMBER: CRD42018092272.

WHO/ILO work-related burden of disease and injury: Protocol for systematic reviews of exposure to occupational noise and of the effect of exposure to occupational noise on cardiovascular disease.

BACKGROUND: The World Health Organization (WHO) and the International Labour Organization (ILO) are developing a joint methodology for estimating the national and global work-related burden of disease and injury (WHO/ILO joint methodology), with contributions from a large network of experts. In this paper, we present the protocol for two systematic reviews of parameters for estimating the number of deaths and disability-adjusted life years from cardiovascular disease attributable to exposure to occupational noise, to inform the development of the WHO/ILO joint methodology. OBJECTIVES: We aim to systematically review studies on exposure to occupational noise (Systematic Review 1) and systematically review and meta-analyse estimates of the effect of occupational noise on cardiovascular diseases (Systematic Review 2), applying the Navigation Guide systematic review methodology as an organizing framework, conducting both systematic reviews in tandem and in a harmonized way. DATA SOURCES: Separately for Systematic Reviews 1 and 2, we will search electronic academic databases for potentially relevant records from published and unpublished studies, including Medline, EMBASE, Web of Science and CISDOC. We will also search electronic grey literature databases, Internet search engines and organizational websites; hand search reference list of previous systematic reviews and included study records; and consult additional experts. STUDY ELIGIBILITY AND CRITERIA: We will include working-age (≥15 years) workers in the formal and informal economy in any WHO and/or ILO Member State, but exclude children (<15 years) and unpaid domestic workers. The eligible risk factor will be occupational noise. Eligible outcomes will be hypertensive heart disease, ischaemic heart disease, stroke, cardiomyopathy, myocarditis, endocarditis and other circulatory diseases. For Systematic Review 1, we will include quantitative prevalence studies of exposure to occupational noise (i.e., low: <85 dB(A) and high: ≥85 dB(A)) stratified by country, sex, age and industrial sector or occupation. For Systematic Review 2, we will include randomized controlled trials, cohort studies, case-control studies and other non-randomized intervention studies with an estimate of the relative effect of high exposure to occupational noise on the prevalence of, incidence of or mortality due to cardiovascular disease, compared with the theoretical minimum risk exposure level (i.e., low exposure). STUDY APPRAISAL AND SYNTHESIS METHODS: At least two review authors will independently screen titles and abstracts against the eligibility criteria at a first stage and full texts of potentially eligible records at a second stage, followed by extraction of data from qualifying studies. At least two review authors will assess risk of bias and the quality of evidence, using the most suited tools currently available. For Systematic Review 2, if feasible, we will combine relative risks using meta-analysis. We will report results using the guidelines for accurate and transparent health estimates reporting (GATHER) for Systematic Review 1 and the preferred reporting items for systematic reviews and meta-analyses guidelines (PRISMA) for Systematic Review 2. PROSPERO registration number: CRD42018092272.

[Do hearing threshold levels in workers of the furniture industry reflect their exposure to noise?]. / Czy progi sluchu u pracowników przemyslu meblarskiego wynikaja z ich narazenia na halas?

BACKGROUND: The aim of the study was to analyze the hearing status of employees of a furniture factory with respect to their exposure to noise and the presence of additional risk factors of noise-induced hearing loss (NIHL). MATERIAL AND METHODS: Noise measurements, questionnaire survey and assessment of hearing, using pure tone audiometry, were carried out in 50 male workers, aged 20-57 years, directly employed in the manufacture of furniture. The actual workers' hearing threshold levels (HTLs) were compared with the predictions calculated according to PN-ISO 1999:2000 based on age, gender and noise exposure. RESULTS: Workers under study were exposed to noise at daily noise exposure levels of 82.7-94.8 dB (mean: 90.9 dB) for a period of 3-14 years. In all subjects, mean HTL at 500 Hz, 1000 Hz, 2000 Hz and 4000 Hz did not exceed 25 dB. Nevertheless, high frequency notches were found in 11% of audiograms. The actual workers' HTLs at 3000-6000 Hz were similar to those predicted using PN-ISO 1999:2000. There were statistical significant differences between HTLs in subgroups of people with higher (> 78 mm Hg) and lower (≤ 78 mm Hg) diastolic blood pressure, smokers and non-smokers, and those working with organic solvents. Hearing loss was more evident in subjects affected by the additional risk factors specified above. CONCLUSIONS: The results confirm the need to consider, in addition to noise, also some other NIHL risk factors, such as tobacco smoking, elevated blood pressure, and co-exposure to organic solvents when estimating the risk of NIHL and developing the hearing conservation programs for workers. Med Pr 2016;67(3):337-351.

Self-assessment of hearing status and risk of noise-induced hearing loss in workers in a rolling stock plant.

Noise measurements and questionnaire inquiries were carried out for 124 workers of a rolling stock plant to develop a hearing conservation program. On the basis of that data, the risk of noise-induced hearing loss (NIHL) was evaluated. Additionally, the workers' hearing ability was assessed with the (modified) Amsterdam inventory for auditory disability and handicap, (m)AIADH. The workers had been exposed to noise at A-weighted daily noise exposure levels of 74-110 dB for 1-40 years. Almost one third of the workers complained of hearing impairment and the (m)AIADH results showed some hearing difficulties in over half of them. The estimated risk of hearing loss over 25 dB in the frequency range of 3-6 kHz was 41-50% when the standard method of predicting NIHL specified in Standard No. ISO 1999:1990 was used. This risk increased to 50-67% when noise impulsiveness, coexposure to organic solvents, elevated blood pressure and smoking were included in calculations.

[Sources of occupational exposure to ultrasonic noise]. / Zródla ekspozycji zawodowej na halas ultradzwiekowy--ocena wybranych urzadzen.

BACKGROUND: Ultrasonic noise is defined as broadband noise containing high audible and low ultrasonic frequencies (from 10 kHz to 40 kHz). According to the most advanced knowledge, this type of noise exerts adverse effects on the hearing organ and the vestibular system. The aim of the study was to evaluate exposure to ultrasonic noise in occupational settings and to identify its essential sources. MATERIALS AND METHODS: The measurements of ultrasonic noise emitted by selected so called low frequency ultrasonic technological devices as well as grinders, circular saws, planers and processes, such as plasma-arc welding and air-acetylene welding, and others, were performed. The study concerned 233 workplaces, where the operators were supposed to be exposed to ultrasonic noise. The measurements were made under typical conditions of work and with reference to Polish standard PN-ISO 9612:2004. RESULTS: The sound pressure levels in the 1/3-octave bands from 10 kHz to 25 kHz (sometimes up to 40 kHz) occurring at workplaces exceeded the admissible values for 8-h exposure (maximum admissible intensity (MAI) values for ultrasonic noise) in all investigated cases of ultrasonic lace sewing machines and cutters as well as in 75% of grinders, 59.5% of ultrasonic welders, 42.9% of ultrasonic washers, and 28.6% of saws and planers. Moreover, in the majority (83.3%) of ultrasonic lace sewing machines and in a large part (33.5%) of welders, the recorded sound levels exceeded the admissible values of maximum sound pressure levels (MAI) in 1/3-octave bands. CONCLUSIONS: Our results indicate that ultrasonic welders and lace sewing machines are the major sources of occupational exposure to ultrasonic noise.

[Developing the method for assessing non-occupational exposure to noise]. / Opracowanie metody oceny pozazawodowej ekspozycji na halas.

BACKGROUND: Noise prevailing in the non-occupational environment, such as that experienced in disco or rock concerts may be dangerous to the condition of the human hearing organ. The existing methods for assessing the risk of hearing loss (e.g., specified in ISO 1999:1990) fails to consider the contribution of non-occupational noise to the overall noise exposure. The fact that there is no generally accepted method for assessing the contribution of individual exposures to non-occupational noise to be used in epidemiological studies is one of the reasons that the effect of the quoted ISO procedure is limited. The aim of this study was to develop a method enabling quantitative assessment of the individual level of non-occupational noise exposure and estimation of the exposure uncertainty in large groups of people. MATERIAL AND METHODS: Based on the available literature data and our own results, we established a database on noise levels associated with typical circumstances prevailing in the general environment. A questionnaire was developed to enable collection of data essential for defining individual exposures to non-occupational noise. Using the questionnaire data, a procedure for assessing the level of non-occupational noise exposure was developed and its reliability was determined by assessing the repeatability of the results of two determinations performed every three weeks and comparing the calculated levels of the noise exposures with the true levels. RESULTS: The values of individual non-occupational noise exposure, referred to 8h (LEX, 8h) in the study group of people, using the proposed methods ranged between 69 dB and 80 dB. This method allows to assess individual non-occupational exposures to noise at 1-2 dB error relative to the measured levels. The uncertainty of the method is within 4 dB. CONCLUSIONS: The proposed method enables a reliable assessment of non-occupational exposure to non-occupational noise and may be successfully applied in epidemiological studies.

Ototoxic effects of occupational exposure to styrene and co-exposure to styrene and noise.

Ototoxicity of styrene and the synergistic action of styrene and noise have been shown in rats. The respective data in humans are scarce and equivocal. This study evaluated the effects of occupational exposure to styrene and combined exposures to styrene and noise on hearing. The study group, comprised of 290-yacht yard and plastic factory workers, was exposed to a mixture of organic solvents, having styrene as its main compound. The reference group, totaling 223 subjects, included (1) white-collar workers, exposed neither to solvents nor noise and (2) metal factory workers, exposed exclusively to noise. All subjects were assessed by means of a detailed questionnaire and underwent otorhinolaryngological and audiometric examinations. Multiple logistic regression analysis revealed almost a 4-fold (or 3.9; 95% CI = 2.4-6.2) increase in the odds of developing hearing loss related to styrene exposure. The factors adjusted for were: age, gender, current occupational exposure to noise, and exposure to noise in the past. In cases of the combined exposures to styrene and noise, the odds ratios were two to three times higher than the respective values for styrene-only and noise-only exposed subjects. The mean hearing thresholds--adjusted for age, gender, and exposure to noise--were significantly higher in the solvent-exposed group than in the unexposed reference group at all frequencies tested. A positive linear relationship existed between an averaged working life exposure to styrene concentration and a hearing threshold at the frequencies of 6 and 8 kHz. This study provides the epidemiological evidence that occupational exposure to styrene is related to an increased risk of hearing loss. Combined exposures to noise and styrene seem to be more ototoxic than exposure to noise alone.