Exposure to noise and ototoxic chemicals in the Australian workforce

Sources of noise exposure across Australian workplaces: cross-sectional analysis and modelling the impact of a targeted noise-source reduction initiative

CONTEXT

Workplace noise regulations and guidance follow the hierarchy of control model that prioritizes eliminating or reducing noise at its source.

OBJECTIVES

To determine the main sources of workplace noise exposure in the Australian working population and estimate the reduction of workers exposed over the noise limit (LAeq,8h > 85 dB) if noise levels of specific tools or equipment were reduced by 10 dB.

METHODS

Information on the tools used and tasks performed during each participant's last working shift was collected from 4,977 workers via telephone survey. Using a predetermined database of task-based noise levels, partial noise exposures (Pa2h) were determined for each noisy activity performed by the workers and their daily noise exposure level (LAeq,8h) was estimated. Partial exposures were categorized into 15 tool/task groups and the tally, average, and sum (Pa2h) for each group were calculated. The impacts of 5 different scenarios that simulated a reduction of 10 dB in noise emissions for specific tool groups were modelled.

RESULTS

Powered tools and equipment were responsible for 59.3% of all noise exposure (Pa2h); vehicles for 10.6%; mining, refineries, and plant equipment for 5.1%; and manufacturing and food processing for 4.2%. Modelling demonstrated that a 10 dBA noise-level reduction of all powered tools and equipment would lead to a 26.4% (95% confidence interval: 22.7% to 30.3%) reduction of workers with an LAeq,8h > 85 dB. This could represent over 350,000 Australian workers no longer exposed above the workplace limit daily.

CONCLUSIONS

A universal reduction of 10 dB to power tools and equipment would substantially reduce the future burden of hearing loss, tinnitus, workplace injuries, and other health effects. Initiatives to reduce the noise emissions of specific powered tool groups are warranted.

Impact of occupational noise exposure on the hearing level in hospital staffs: a longitudinal study

The study aimed to evaluate the impact of occupational noise on hearing loss among healthcare workers using audiometry. A longitudinal study was conducted with a six-month follow-up period in a hospital with 21 participants, divided into high-noise-exposure (HNE) and low-noise-exposure (LNE) groups. Mean noise levels were higher in the HNE group (70.4 ± 4.5 dBA), and hearing loss was measured using pure-tone audiometry at baseline and follow-up. The HNE group had significantly higher mean threshold levels at frequencies of 0.25 kHz, 0.5 kHz, 4.0 kHz, and an average of 0.5, 1, 2, and 4 kHz (all p-values < 0.05) after the follow-up period. After adjusting for confounding factors, the HNE group had significantly higher hearing loss levels at 0.25 kHz, 0.5 kHz, and average frequencies of 0.5, 1, 2, and 4 kHz compared to the LNE group at the second measurement. Occupational noise levels above 65 dBA over six months were found to cause significant threshold changes at frequencies of 0.25 kHz, 0.5 kHz, and an average of 0.5-4.0 kHz. This study highlights the risk of noise-induced hearing loss among healthcare workers and emphasizes the importance of implementing effective hearing conservation programs in the workplace. Regular monitoring and assessment of noise levels and hearing ability, along with proper use of personal protective equipment, are crucial steps in mitigating the impact of occupational noise exposure on the hearing health of healthcare workers.

The Associations Between Workplace Noise, Ototoxic Chemicals, and Tinnitus

OBJECTIVE

To investigate the occupational risk factors associated with tinnitus in the Australian working population.

DESIGN

The research was conducted using data collected from the Australian Workplace Exposure Survey-Hearing, a national cross-sectional study of 4970 workers conducted in 2016 to 2017. Workers were asked if they experienced tinnitus and if they answered affirmatively, they were asked about the frequency and length of the presentations. Based on their answers, each worker was categorized as having no tinnitus or any tinnitus, with an additional group of workers with any tinnitus subcategorized as having constant tinnitus. Exposure assessment was conducted using an automated expert assessment method. Exposures included daily noise (L Aeq,8h ), hand-arm vibration (A(8)), impulse noise, smoking status, styrene, trichloroethylene, toluene, n-hexane, p-xylene, ethylbenzene, lead, and carbon monoxide. Univariate and multivariate logistic regression models were used to examine the associations between workplace exposures and tinnitus.

RESULTS

Workers with an estimated noise exposure above the workplace limit (L Aeq,8h > 85 dBA) had 1.73 (95% confidence interval [CI]: 1.42 to 2.11) increased odds of any tinnitus and 2.15 (95% CI: 1.60 to 2.89) odds of constant tinnitus. The odds of workers having any tinnitus increased with increasing noise exposure levels in a dose-response relationship that strengthened when considering only those with constant tinnitus. In the fully adjusted model, statistically significant associations were seen for lead exposure with both any and constant tinnitus, toluene exposure with constant tinnitus, and carbon monoxide exposure with any tinnitus.

CONCLUSIONS

These results suggest that, in addition to workplace noise, occupational exposures to lead, toluene, and carbon monoxide are associated with tinnitus.

Evaluating the potential impact of ototoxicant exposure on worker health

Occupational exposure to ototoxicants, substances that can cause hearing loss alone or exacerbate hearing loss when exposure occurs in combination with noise, is a workplace hazard that is poorly understood. A review of existing research indicates that some solvents and heavy metals may be ototoxic, but few studies have attempted to estimate the impact of ototoxicant exposure on the United States worker population. Researchers examined trends in workplace exposure to ototoxicants among workers in the United States by comparing exposure data collected by the Occupational Safety and Health Administration against worker hearing loss data provided by the Bureau of Labor Statistics (BLS) for 2012-2019. The study found that the noise exposure data was strongly correlated to the hearing loss data using Pearson's correlation (p < .001), confirming that the exposure data collected by OSHA is predictive of the risk of occupational illness as reported by BLS. Chi-square analysis indicates that reported hearing loss was more common among industry subsectors with exposure to ototoxicants than those without exposure to ototoxicants. These findings suggest that workers with coexposure to ototoxicants and noise may be at a higher risk of experiencing hearing loss than those exposed to noise alone, and action should be taken to minimize this risk.

Comparison of agreement in asthmagen exposure assessments between rule-based automatic algorithms and a job exposure matrix in healthcare workers in Australia and Bhutan

Background:

Assessment of occupational exposures is an integral component of population-based studies investigating the epidemiology of occupational diseases. However, all the available methods for exposure assessment have been developed, tested and used in high-income countries. Except for a few studies examining pesticide exposures, there is limited research on whether these methods are appropriate for assessing exposure in LMICs. The aim of this study is to compare a task-specific algorithm-based method (OccIDEAS) to a job-specific matrix method (OAsJEM) in the assessment of asthmagen exposures among healthcare workers in a high-income country and a low- and middle- income country (LMIC) to determine an appropriate assessment method for use in LMICs for future research.

Methods:

Data were obtained from a national cross-sectional survey of occupational asthmagens exposure in Australia and a cross-sectional survey of occupational chemical exposure among Bhutanese healthcare workers. Exposure was assessed using OccIDEAS and the OAsJEM. Prevalence of exposure to asthmagens and inter-rater agreement were calculated.

Results:

In Australia, the prevalence was higher for a majority of agents when assessed by OccIDEAS than by the OAsJEM (13 versus 3). OccIDEAS identified exposures to a greater number of agents (16 versus 7). The agreement as indicated by κ (Cohen’s Kappa coefficient) for six of the seven agents assessed was poor to fair (0.02 to 0.37). In Bhutan, the prevalence of exposure assessed by OccIDEAS was higher for four of the seven agents and κ was poor for all the four agents assessed (-0.06 to 0.13). The OAsJEM overestimated exposures to high-level disinfectants by assigning exposures to all participants from 10 (Bhutan) and 12 (Australia) ISCO-88 codes; whereas OccIDEAS assigned exposures to varying proportions of participants from these ISCO-codes.

Conclusion:

There was poor to fair agreement in the assessment of asthmagen exposure in healthcare workers between the two methods. The OAsJEM overestimated the prevalence of certain exposures. As compared to the OAsJEM, OccIDEAS appeared to be more appropriate for evaluating cross-country exposures to asthmagens in healthcare workers due to its inherent quality of assessing task-based determinants and its versatility in being adaptable for use in different countries with different exposure circumstances.

A risk model and nomogram for high-frequency hearing loss in noise-exposed workers

Background

High-frequency hearing loss is a significant occupational health concern in many countries, and early identification can be effective for preventing hearing loss. The study aims to construct and validate a risk model for HFHL, and develop a nomogram for predicting the individual risk in noise-exposed workers.

Methods

The current research used archival data from the National Key Occupational Diseases Survey-Sichuan conducted in China from 2014 to 2017. A total of 32,121 noise-exposed workers completed the survey, of whom 80% workers (n = 25,732) comprised the training cohort for risk model development and 20% workers (n = 6389) constituted the validation cohort for model validation. The risk model and nomogram were constructed using binary logistic models. The effectiveness and calibration of the model were evaluated with the receiver operating characteristic curve and calibration plots, respectively.

Results

A total of 10.06% of noise-exposed workers had HFHL. Age (OR = 1.09, 95% CI: 1.083–1.104), male sex (OR = 3.25, 95% CI: 2.85–3.702), noise exposure duration (NED) (OR = 1.15, 95% CI: 1.093–1.201), and a history of working in manufacturing (OR = 1.50, 95% CI: 1.314–1.713), construction (OR = 2.29, 95% CI: 1.531–3.421), mining (OR = 2.63, 95% CI: 2.238–3.081), or for a private-owned enterprise (POE) (OR = 1.33, 95% CI: 1.202–1.476) were associated with an increased risk of HFHL (P < 0.05).

Conclusions

The risk model and nomogram for HFHL can be used in application-oriented research on the prevention and management of HFHL in workplaces with high levels of noise exposure.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-10730-y.

Exposure to lead, mercury, styrene, and toluene and hearing impairment: evaluation of dose-response relationships, regulations, and controls

The risk of hearing loss from exposure to ototoxic chemicals is not reflected in occupational exposure limits and most jurisdictions. The aims of this research were to investigate dose-response relationships between exposure to lead, mercury, toluene, and styrene and hearing impairment based on current epidemiological evidence, conduct cross-jurisdictional comparisons, and investigate control measures for exposure to ototoxic chemicals. Ovid Medline and Ovid Embase databases were used to find relevant publications. A total of 86 epidemiological studies met the eligibility criteria for final evaluation. When significant associations between exposure and outcome were identified, exposure levels were evaluated to determine whether No Observed Adverse Effect Level (NOAEL) and Lowest Observed Adverse Effect Level (LOAEL) could be identified. Cross-jurisdictional comparisons included the U.K., U.S., Canada, and Australia occupational health and safety legislations. The majority of lead (75%), styrene (74%), and toluene (77%) studies showed significantly increased risks of hearing loss from exposure to these substances, although numerous studies on toluene (70%) and styrene (16%) compared auditory function between "solvent mixture" or "noise and solvent mixture" exposed groups and controls and not necessarily on groups exposed to a single agent. Based on five studies, blood lead ranges of 1-1.99 μg/dL to 2.148-2.822 μg/dL were identified as NOAELs while blood lead levels of 2 μg/dL up to 2.823-26.507 μg/dL were identified as LOAELs for hearing loss. Except for general duty clauses, the U.S., Canadian, and Australian jurisdictions have set no enforceable regulations specific to ototoxic chemical exposures. A biological exposure index of 2 μg/dL is recommended for prevention of hearing impairment from lead exposure. Based on Safe Work Australia, noise exposure limits may be reduced to 80 dB(A) for 8 hr. Other recommendations include performing audiometric testing and controlling exposure through all routes of entry.

Productivity Burden of Occupational Noise-Induced Hearing Loss in Australia: A Life Table Modelling Study

Background: Occupational noise-induced hearing loss (ONIHL) is one of the most common yet preventable occupational diseases. The aim of this study was to estimate the economic burden of ONIHL in the Australian working population by quantifying and monetising ONIHL-related loss of Quality Adjusted Life Years (QALY) and Productivity Adjusted Life Years (PALYs). Methods: We simulated the number of moderate-to-severe ONIHL by multiplying the age-specific prevalence of occupational noise exposure by the excess risks of ONIHL. Life table modelling was applied to workers with ONIHL. The QALY and PALY weights attributable to hearing loss were sourced from published data. The 2016 Gross Domestic Product per full-time equivalent worker in Australia was used to estimate the cost of productivity loss due to ONIHL. The cost due to the loss of well-being was quantified using willingness to pay thresholds derived from an Australian longitudinal study. Results: Under current occupational noise exposure levels in Australia, we estimated that over 80,000 male workers and over 31,000 female workers would develop ONIHL over 10 years of exposure. Following this cohort until the age of 65 years, the estimated loss of QALYs and PALYs were 62,218 and 135,561 respectively, with a projected loss of AUD 5.5 billion and AUD 21.3 billion due to well-being and productivity loss, respectively. Reducing noise exposure at work would substantially reduce the economic burden of ONIHL. Conclusion: ONIHL imposes substantial burden on Australian economy. Interventions to reduce occupational noise exposure are warranted.

Chemicals, noise and occupational hearing health in South Africa: A mapping study

BACKGROUND

Chemical exposure leading to ototoxicity is a fresh challenge for occupational healthcare in South Africa.

OBJECTIVES

The critical question is: 'what is known about occupational ototoxic chemicals with or without noise exposure in South Africa?'

METHOD

This qualitative, mapping study was completed with published (peer-reviewed) and grey literature from 1979-2019. Data was analysed using the Preferred Reporting Items for Systematic reviews and Meta-Analyses: extension for Scoping Reviews and the Nursing and Allied Health Resources Section subcommittee on Mapping the Literature of Nursing and Allied Health (adapted). Numerical analysis of article type was completed, but the primary focus was on capturing patterns/trends using thematic analysis and ideology critique.

RESULTS

The African Journal of Disability, African Journal of Primary Health Care and Family Medicine, South African Medical Journal, The South African Journal of Communication Disorders [SAJCD] and Health SA Gesondheid) were included with the SAJCD containing one relevant item and seventeen other items were analysed. Research focusses on the mining sector (gold) in Gauteng, and ototoxic medication (tuberculosis and/or human immunodeficiency virus) take precedence. In KwaZulu-Natal, the focus is on commerce and industry across formal and informal sectors. There are no governmental policies that refer to chemical ototoxicity. Occupational hearing loss is configured exclusively on the meme that noise exposure is the only toxin.

CONCLUSION

Chemical exposures are only just beginning to be recognised as ototoxic in South Africa. Hearing conservation programmes should always serve the workers' interests and never bow down to the econometric interests of employers.

Using Decision Rules to Assess Occupational Exposure in Population-Based Studies

PURPOSE OF REVIEW

Population-based studies increasingly link task-based occupational questionnaire responses collected from subjects to exposure estimates via transparent, programmable decision rules. We reviewed recent applications and methodological developments of rule-based approaches.

RECENT FINDINGS

Agent-specific decision rules require interviews incorporating work-task-based questions. Some studies have developed rules before the interviews took place, while others developed rules after the interviews were completed. Agreement between rule-based estimates and exposures assigned using job-by-job expert review were generally moderate to good (Kappa = 0.4-0.8). Rules providing quantitative intensity levels using measurement data or that integrate multiple independent exposure sources for the same job represent further advances to improve the characterization of occupational exposures in population studies. Decision rules have provided transparent and reproducible assessments, reduce job-by-job review, and facilitate sensitivity analyses in epidemiologic studies. Future studies should consider the development of decision rules concurrent with the questionnaire design to facilitate occupational exposure assessment efforts.