Risk versus benefit: Should not audiologists assess this in the context of occupational noise-induced hearing loss in the mining industry?

BACKGROUND: Hearing conservation programmes (HCPs) are an important aspect of occupational health efforts to prevent occupational noise-induced hearing loss (ONIHL). In low- and middle income (LAMI) countries, where the incidence of ONIHL is significant, it is important to deliberate on the risk or benefit of HCPs. OBJECTIVES: This article is an attempt at highlighting important strategic indicators as well as important variables that the occupational health and audiology community need to consider to plan efficacious HCPs within the South African mining context. METHOD: The current arguments are presented in the form of a viewpoint publication. RESULTS: Occupational audiology vigilance in the form of engagement with HCPs in the mining industry has been limited within the South African research and clinical communities. When occupational audiology occurs, it is conducted by mid-level workers and paraprofessionals; and it is non-systematic, non-comprehensive and non-strategic. This is compounded by the current, unclear externally enforced accountability by several bodies, including the mining industry regulating body, with silent and/or peripheral regulation by the Health Professions Council of South Africa and the Department of Health. The lack of involvement of audiologists in the risk or benefit evaluation of HCPs during their development and monitoring process, as well as their limited involvement in the development of policies and regulations concerning ear health and safety within this population are probable reasons for this. CONCLUSIONS: Increased functioning of the regulatory body towards making the employers accountable for the elimination of ONIHL, and a more central and prominent role for audiologists in HCPs, are strongly argued for.

Cost-Effective Hearing Conservation: Regulatory and Research Priorities.

Hearing conservation programs (HCPs) mandated by the US Occupational Safety and Health Administration (OSHA) cost about $350/worker/year. Are they cost-effective? A cross-sectional model of the US adult population with and without HCPs incorporates (1) the American Medical Association's method for estimating binaural hearing impairment and whole-person impairment; (2) the model of the International Organization for Standardization (ISO) for estimating both age-related and noise-induced hearing loss; and (3) an acceptable cost of $50,000 per quality-adjusted life year. The ISO model's outputs were audiometric thresholds for groups of people with different age, sex, and noise exposure history. These thresholds were used to estimate cost per quality-adjusted life year saved for people in HCPs with different noise exposure levels. Model simulations suggest that HCPs may be cost-effective only when time-weighted average (TWA) noise exposures are ≥ 90 dBA. Enforcing existing regulations, requiring engineering noise control at high exposure levels, and using new methods that can document hearing protection device performance could improve cost-effectiveness. If the OSHA action level remains at 85 dBA-TWA, reducing the permissible exposure limit to the same level would simplify management and slightly improve cost-effectiveness. Research should evaluate employer compliance across industries, determine whether workers currently excluded from HCP regulations are at risk of noise-induced hearing loss, and develop cost-effective HCPs for mobile workers in construction, agriculture, and oil and gas drilling and servicing. Research on HCP cost-effectiveness could be extended to incorporate sensitivity analyses of the effects of a wider range of assumptions.

Commentary on the regulatory implications of noise-induced cochlear neuropathy.

OBJECTIVE: A discussion on whether recent research on noise-induced cochlear neuropathy in rodents justifies changes in current regulation of occupational noise exposure. DESIGN: Informal literature review and commentary, relying on literature found in the authors' files. No formal literature search was performed. STUDY SAMPLE: Published literature on temporary threshold shift (TTS) and cochlear pathology, in humans and experimental animals, as well as the regulations of the US Occupational Safety and Health Administration (OSHA). RESULTS: Humans are less susceptible to TTS, and probably to cochlear neuropathy, than rodents. After correcting for inter-species audiometric differences (but not for differences in susceptibility), exposures that caused cochlear neuropathy in rodents already exceed OSHA limits. Those exposures also caused "pathological TTS" (requiring more than 24 h to recover), which does not appear to occur with human broadband noise exposure permissible under OSHA. CONCLUSION: It would be premature to conclude that noise exposures permissible under OSHA can cause cochlear neuropathy in humans.

A vision of the environmental and occupational noise pollution in Malaysia.

Environmental noise remains a complex and fragmented interplay between industrialization, population growth, technological developments, and the living environment. Next to the circulatory diseases and cancer, noise pollution has been cited as the third epidemic cause of psychological and physiological disorders internationally. A reliable and firm relationship between the cumulative health implications with the traffic annoyance and occupational noise has been established. This agenda has called for an integrated, coordinated, and participatory approach to the reliable protection of noise interference. Despite several fragmented policies, legislation and global efforts have been addressed; the noise pollution complaints have been traditionally neglected in developing countries, especially in Malaysia. This paper was undertaken to postulate an initial platform to address the dynamic pressures, gigantic challenges, and tremendous impacts of noise pollution scenario in Malaysia. The emphasis is speculated on the traffic interference and assessment of industrial and occupational noise. The fundamental importance of noise monitoring and modeling is proposed. Additionally, the confronting conservation program and control measure for noise pollution control are laconically elucidated.

Is it necessary to penalize impulsive noise +5 dB due to higher risk of hearing damage?

It is studied whether the +5 dB penalty for impulsiveness established by ISO 1999:1990 accounts for a higher risk of noise-induced hearing loss. A total of 16 normal-hearing human subjects were exposed for 10 min to two types of binaural industrial-recordings: (1) a continuous broad-band noise normalized to L(EX,8 h)=80 dBA and (2) the combination of the previous stimulus with an impulsive noise normalized to L(EX,8 h)=75+5(db penalty)=80 dBA (peak level 117 dBC and repetition rate of 0.5 impacts per second). Distortion product otoacoustic emissions (DPOAEs) were measured in a broad frequency range before and in the following 90 min after the exposure. The group results show that the continuous exposure had a bigger impact on DPOAE levels, with a maximum DPOAE shift of approximately 5 dB in the frequency range of 2-3.15 kHz during the first 10 min of the recovery. No evident DPOAE shift is seen for the impulsive + continuous stimulus. The results indicate that the penalty overestimated the effects on DPOAE levels and support the concept that the risk of hearing loss from low-level impulses may be predicted on an equal-energy basis.

Medicolegal significance of asymmetrical hearing loss in cases of industrial noise exposure.

OBJECTIVE: In Australia, the current guidelines for evaluation of noise-induced hearing loss suggest that, in cases of asymmetrical loss, 'the worse ear be equated to the better ear' for purposes of compensation. This study aimed to establish that such a method was prejudicial to the worker (i.e. the plaintiff). In consideration of the legal duty 'to co-construct the ideas of truth and the ideas of justice in the context of legal proceedings', our study objectives were (1) to document the incidence of asymmetrical hearing loss in compensation cases seen in our practice, and (2) to provide a reasoned argument for inclusion of the same for compensation considerations. STUDY DESIGN: Open, retrospective, clinical study. SETTING: Australian plaintiffs with asymmetrical hearing loss (who comprise a significant percentage of industrial hearing loss legal cases) may be excluded from full consideration of their hearing loss as a result of the current guidelines. In contrast to the process of medical diagnosis and treatment, it appeared that the application of accepted probability standards within the legal process may permit inclusion of such clients' hearing loss in compensation considerations. METHODS: This study included 208 consecutive clients referred by legal practitioners for assessment of hearing loss for compensation purposes. RESULTS AND CONCLUSION: A total of 22.6 per cent of clients (47 of 208) had asymmetrical hearing loss, with the left side having the greater loss in 60 per cent of cases. We believe that asymmetrical hearing loss should be included in compensation considerations, both on medical and legal grounds.

Exposição a ruído e hipertensão arterial: investigação de uma relação silenciosa / Noise exposure and hypertension: investigation of a relationship quiet

O ruído é o agente mais frequentemente associado às alterações na saúde dos trabalhadores e é também o risco ocupacional mais universalmente distribuído. No Brasil, mais da metade dos trabalhadores de indústrias são expostos a níveis de ruído acima dos limites legais. Consequentemente, a exposição ao ruído constitui um problema de saúde pública em nosso meio, principalmente no âmbito da Saúde do Trabalhador e seu ambiente.As atividades relacionadas ao refinamento do petróleo expõe os trabalhadores a elevados níveis de ruído devido, principalmente, ao funcionamento de uma grande quantidade de máquinas e equipamentos próprios do beneficiamento do petróleo e também devido às frequentes obras de modernização, ampliação e manutenção das instalações. Os efeitos da exposição ao ruído na audição foram amplamente documentados por autores nacionais e internacionais e as evidências encontradas nos estudos epidemiológicos são bastante consistentes. Entretanto, outras alterações na saúde também podem ser ocasionadas ou agravadas pela exposição ao ruído, como transtornos digestivos e comportamentais, alterações do sono e dos níveis de cortisol sérico, transtornos cardiovasculares e também à maior incidência de acidentes de trabalho. Alterações cardiovasculares e, especificamente, a hipertensão arterial, foram os efeitos extra-auditivos mais investigados mundialmente. Todavia, o pequeno número de estudos realizados no Brasil faz com que tal associação seja foco de nova investigação. Desta forma, investigou-se a associação entre exposição a ruído ocupacional maior ou igual 75 dBA e hipertensão arterial, através de um estudo transversal com dados secundários de saúde e de exposição ao ruído, de 1729 trabalhadores terceirizados de uma refinaria de petróleo e gás da cidade do Rio de Janeiro, controlado por variáveis confundidoras...

Noise is the agent that is most frequently associated with changes in workers' health and it is also the most universally distributed occupational risk. In Brazil, more than half of industrial workers are exposed to noise levels above the legal limit. Therefore, exposure to noise is a public health issue, especially under the Occupational Health and its environment. The activities related to oil refining exposes workers to high levels of noise, especially, due to the operation of a large quantity of machinery and equipment used on oil processing and also due to frequent modernization, expansion and maintenance of facilities. The effects of exposure to noise in hearing have been widely documented by national and international authors and the evidence found in epidemiological studies is quite consistent. However, other changes in health can also be caused or aggravated by noise exposure, such as digestive and behavioral disorders, sleep disturbances, increase of serum cortisol levels, cardiovascular disorders and also a higher incidence of accidents at work. Cardiovascular changes, specifically hypertension, were the most extra-auditory effects investigated worldwide. However, the small number of studies conducted in Brazil makes this association the focus on further research. Thus, we investigated the association between occupational noise exposure ≥ 75 dBA and hypertension, through a cross-sectional study with secondary data on health and noise exposure, of 1729 contract workers from an oil refinery and gas in the city of Rio de Janeiro, controlled for potential confounders. We used odds ratio (OR) as the association measurement between noise exposure and hypertension...

[Noise related risk: assessment of the efficacy of the prevention in the light of the new legislation]. / Il rischio da rumore: controllo dell'efficacia della prevenzione alla luce delle nuove normative.

Italian law on occupational exposure to noise identify 87 dBA as ceiling exposure level and 80 dBA as action level; the respect of ceiling level can be achieved by using devices, as ear plugs, whose efficacy must be verified. We studied 8119 audiometric of workers exposed to noise between 80 and 87 dBA. The hearing level of those who use ear plugs is significantly better than who don't use. Different devices show different efficacy, but for all, in the exposure setting studied, the level of protection that is provided is enough safe for othological protection. The workers must be informed about the efficacy of the protection and sensibilized to the use of the ear plugs within the periodical clinical surveillance.

[Assessment of occupational noise exposure: methodology, measurement error, evaluation criteria]. / La valutazione dell'esposizione professionale al rumore procedure, errore di misura, criterio di decisione.

BACKGROUND: Occupational noise exposure can be monitored directly by personal sampling or indirectly, by area sampling. Personal sampling is performed using an integrating sound level meter, worn by the worker while performing his/her job. When area sampling is used, measurements need to be made in all locations where a typical worker stays while performing his/her tasks; the respective partial lengths of exposure need to be accurately monitored, and the time-weighted average sound level of the measured noise levels must be calculated. OBJECTIVES: Current regulations identify three different thresholds, corresponding to different types of action, but they do not propose any standard criteria to decide whether a threshold has been exceeded. Defining standard procedures to assess occupational noise exposure and identifying such thresholds is crucial. METHODS: Using empirical data collected in the field, the effects are illustrated of the number of sampling locations and of the partial lengths of exposure on area sampling measurements, and the effects of duration of noise exposure on both area and personal samplings. RESULTS: When dealing with area samplings, an accurate definition of both sampling locations and partial lengths of exposure is crucial. When arbitrary decisions are taken in selecting sampling locations and/or establishing partial lengths of exposure, spatial changes in noise level and operator' displacements while performing his/her tasks may affect results. Sampling for less than the duration of noise exposure is the major contributor to measurement error, particularly under conditions of unpredictable variation in noise level. In fact, as noise level in the non-monitored time fraction is unknown, measurement error cannot be determined. We estimate that, even under the most favorable circumstances, sampling should last not less than 40% of the duration of a given noise-generating occurrence, for repeated measurements to be dispersed within a range not wider than that generated by the instrumental error. Inter-daily variability is another important aspect in personal noise exposure evaluation. This is a general occurrence, whose effects cannot be controlled by simply considering weekly instead of daily exposures. Results of an investigation, covering about 60 different jobs within a primary aluminum plant, show an inter-daily variability in noise exposure greater than 5 dBA in about 75% of cases. CONCLUSIONS: Personal sampling, when correctly performed and covering the total duration of exposure, provides the most reliable result as it integrates noise over all locations where the worker actually stays while performing his/her tasks, and over the total length of time spent in each task. We propose extending personal sampling to the total duration of actual noise exposure as the standard procedure for monitoring daily personal noise exposure, and valid for the majority of work places. When the range of daily noise exposure includes one regulatory threshold, corresponding to a given type of action, we propose as a standard decision criterion to refer prudentially to the upper 95% confidence limit of the LEP,d arithmetic mean. Such criterion would allow to standardize procedures and decision methods, with the prospect of further improvements in the assessment of exposure to noise.

Does your audiometric monitoring program measure up?

All hearing conservation programs under CFR 1910.95 require audiometric monitoring. This article provides an overview of OSHA noncompliance citations related to audiometric monitoring and associated monetary penalties reported between January 1988 and June 1994. The data in this article reflect the degree of seriousness of different elements of noncompliance, because monetary penalties, at least empirically, are related to severity or importance of the element.

[Medical surveillance of occupational hearing loss]. / Vigilancia médica de la hipoacusia profesional.

Audiometric tests at noisy workplaces serve as a means for the early detection of noise-induced hearing loss. As such a tool for secondary prevention, the conditions under which they are to be made and the factors which may influence their effectiveness: sources of error, hearing loss due to old age, testing intervals, significant hearing loss readings and criteria for referral to ear specialists are analyzed. These aspects are also compared with that which has been set forth is the Decree recently published regarding the medical checkups of workers exposed to noise, in which these criteria are not taken into account. Some norms to complement this Decree, in which, in addition to describing the conditions for carrying out audiometric tests, proposals regarding methods for interpreting the results thereof, measures for following up on said results and proposals for an epidemiological analysis of the data must be made. Advantage must also be taken of this occasion to define new norms for qualification as a professional and the medical-legal compensation for on-the-job noise-induced hearing loss.