Relationship between night work and health-related quality of life: an analysis based on profiles and cumulative duration of exposure to night work among French workers in the CONSTANCES cohort.

OBJECTIVE: The aim of this study is to estimate the association between night work and health-related quality of life (HRQoL) among French workers. The association between cumulative duration of night work and HRQoL was also investigated. METHODS: Three career-long night work exposure groups were defined at inclusion in the CONSTANCES cohort: permanent night workers, rotating night workers and former night workers. Day workers with no experience of night work were the reference group. HRQoL was assessed using the Short Form Health Survey (SF-12), in particular the physical component summary (PCS) and mental component summary (MCS) scores, with a higher score indicating better HRQoL. Several linear regression models were built to test the association between night work exposure and HRQoL. The relationship between cumulative duration of night work and HRQoL scores was analyzed using generalised additive models. RESULTS: The sample consisted of 10,372 participants. Former night workers had a significantly lower PCS score than day workers (ß [95% CI]: - 1.09 [- 1.73; - 0.45], p = 0.001), whereas permanent night workers had a significantly higher MCS score (ß [95% CI]: 1.19 [0.009; 2.36], p = 0.048). A significant decrease in PCS score from 5 to 20 years of cumulative night work was observed among former night workers. CONCLUSIONS: Former night workers had poorer physical HRQoL in contrast to permanent and rotating night workers who had similar or even better HRQoL than day workers, suggesting the well-known healthy worker survivor effect. Consequently, both current and former night workers require regular and specific follow-up focused on the physical components of their health.

Breast cancer and occupation: Non-parametric and parametric net survival analyses among Swiss women (1990-2014).

Introduction: Occupation can contribute to differences in risk and stage at diagnosis of breast cancer. This study aimed at determining whether occupation, along with skill level and the socio-professional category, affect the breast cancer survival (BCS) up to 10 years after diagnosis. Materials and methods: We used cancer registry records to identify women diagnosed with primary invasive breast cancer in western Switzerland over the period 1990-2014 and matched them with the Swiss National Cohort. The effect of work-related variables on BCS was assessed using non-parametric and parametric net survival methods. Results: Study sample included 8,678 women. In the non-parametric analysis, we observed a statistically significant effect of all work-related variables on BCS. Women in elementary occupations, with low skill level, and in paid employment not classified elsewhere, had the lowest BCS, while professionals, those with the highest skill level and belonging to top management and independent profession category had the highest BCS. The parametric analysis confirmed this pattern. Considering elementary occupations as reference, all occupations but Craft and related trades had a hazard ratio (HR) below 1. Among professionals, technicians and associate professionals, and clerks, the protective effect of occupation was statistically significant and remained unchanged after adjustment for age, calendar period, registry, nationality, and histological type. After adjusting for tumor stage, the HRs increased only slightly, though turned non-significant. The same effect was observed in top management and independent professions and supervisors, low level management and skilled laborers, compared to unskilled employees. Conclusion: These results suggest that work-related factors may affect BCS. Yet, this study was conducted using a limited set of covariates and a relatively small study sample. Therefore, further larger studies are needed for more detailed analyses of at risk occupations and working conditions and assessing the potential interaction between work-related variables and tumor stage.

Low Back Pain and Upper-Extremity Musculoskeletal Disorders in French Postal Workers Driving Light-Duty Vehicles for Mail and Parcel Delivery.

Occupational driving of light-duty vehicles (LDVs) became increasingly important in parcel delivery faced with the explosive growth of e-commerce. Since musculoskeletal disorders (MSDs) represent the most reported driving-related health problem, we aimed to analyze the risk of low back pain (LBP) and upper-extremity musculoskeletal disorders (UEMSDs) associated with driving LDVs for parcel delivery. In 306 postal workers exposed to driving and 100 unexposed workers, information on occupational driving, physical/psychosocial constraints, and work organization were collected via a questionnaire. MSDs were assessed using the Nordic Questionnaire, 14 additional questions regarding LBP, and a standardized clinical examination for UEMSDs. Statistical modeling consisted of multivariable logistic regression for UEMSDs and the item response theory approach for LBP. UEMSDs were associated with the distance of rural rounds and inversely associated with urban/mixed delivery rounds. Handling heavy loads was associated with LBP, and high physical demands during delivery rounds were related to MSDs. Karasek dimensions and mobbing actions were associated with MSDs. Work recognition, driving training, using an automatic gearbox, and the utilization of additional staff during peak periods were inversely associated with MSDs. Our results suggest that the distance driven in rural settings and high physical demands were associated with MSDs, while some organizational factors could protect from MSDs.

Work-Related Factors and Lung Cancer Survival: A Population-Based Study in Switzerland (1990-2014).

While previous Swiss studies have demonstrated differences in lung cancer mortality between occupational groups, no estimates are available on the association of occupation-related factors with lung cancer survival. This study aimed at determining whether occupation or work-related factors after diagnosis affect lung cancer survival. We used cancer registry records to identify lung cancer patients diagnosed between 1990 and 2014 in western Switzerland (n = 5773) matched with the Swiss National Cohort. The effect of occupation, the skill level required for the occupation, and the socio-professional category on 5-year lung cancer survival was assessed using non-parametric and parametric methods, controlling for histological type and tumour stage. We found that the net survival varied across skill levels and that the lowest skill level was associated with worse survival in both men and women. In the parametric models with minimal adjustment, we identified several occupational groups at higher risk of mortality compared to the reference category, particularly among men. After adjustment for histological type of lung cancer and tumour stage at diagnosis, most hazard ratios remained higher than 1, though non-statistically significant. Compared to top managers and self-employed workers, workers in paid employment without specific information on occupation were identified as the most at-risk socio-professional category in nearly all models. As this study was conducted using a relatively small sample and limited set of covariates, further studies are required, taking into account smoking habits and administrated cancer treatments. Information on return to work and working conditions before and after lung cancer diagnosis will also be highly valuable for analysing their effect on net lung cancer survival in large nationwide or international studies. Such studies are essential for informing health and social protection systems, which should guarantee appropriate work conditions for cancer survivors, beneficial for their quality of life and survival.

Longitudinal predictors of bronchial hyperresponsiveness and FEV1 decline in bakers.

OBJECTIVE: To determine long-term predictors of bronchial hyperresponsiveness (BHR) and forced expiratory volume in one second (FEV1) decline. METHODS: A longitudinal study in 110 bakers in 4 industrial bakeries and 38 non-exposed workers was conducted at the workplace with a mean of 3.3 visits per subject over a period of 13 years and a mean duration of follow-up of 6 years in bakers and 8 years in non-exposed subjects. A respiratory health questionnaire was administered; occupational allergen skin prick tests, spirometry and a methacholine bronchial challenge test were performed at each visit. In each bakery, full-shift dust samples of the inhalable fraction were obtained in order to assess the exposure of each job assignment. The repeated measurements of BHR and FEV1 were analyzed using mixed effects logistic and linear regression models in subjects seen at least twice. RESULTS: BHR, respiratory symptoms and their simultaneous occurrence depended on the duration of exposure. FEV1 significantly decreased with duration of exposure and BHR at a preceding visit. This result persisted when adjusting for the effect of BHR at the current visit. The measured exposure levels were not a significant predictor for any outcome. Occupational sensitization was only a predictor of a decline in FEV1 when duration of exposure was not included. CONCLUSION: In flour-exposed industrial bakers, length of exposure and smoking are long-term determinants of BHR and of the decrease in FEV1. BHR at a preceding visit predicted lower FEV1 even when accounting for the effect of BHR at the current visit.

Effects of plant features on symptoms and airway inflammation in compost workers followed over 18 months.

This study investigated the plant features associated with increased irritation symptoms and levels of inflammation markers among compost workers (CWs). Ninety CWs were followed over 18 months, using questionnaires on respiratory symptoms, fractional exhaled nitric oxide measurements, spirometry, a methacholine bronchial challenge test, and quantification of specific immunoglobulins E (IgE) and G. CWs in plants processing the highest quantities of waste exhibited more airway irritation symptoms. So did the CWs in partially and fully indoor plants as compared to those in plants entirely outdoors. Working in sewage sludge versus green waste plants and having a high level of exposure were associated with higher levels of different IgE. The duration of employment decreased the FEV1 by 16 ml per year. Working in an indoor plant is linked to symptoms and inflammation markers in CWs.

Is the effect of work-related psychosocial exposure on depressive and anxiety disorders short-term, lagged or cumulative?

PURPOSE: To determine the short-term, lagged, and cumulative effects of psychosocial factors (PSF) on the incidence of depression and anxiety. METHOD: Major depressive disorders (MDD) and generalized anxiety disorders (GAD) were diagnosed in 2006 and 2010 using the Mini International Neuropsychiatric Interview among 5684 workers from the French SIP cohort. The outcome considered here was diagnosis of MDD and/or GAD (MDD/GAD) in 2010. The frequency of 17 PSF, covering labour intensity and working time, emotional demand, autonomy, social relationships, conflict of values, and job insecurity, was self-reported in 2006 and 2010. For each PSF, four groups (A-D) were considered: exposed neither in 2006 nor in 2010 (A as the reference), exposed in 2010 but not in 2006 (B as a short-term association), exposed in 2006 but not in 2010 (C as a lagged association), exposed in both 2006 and 2010 (D as a cumulative association). RESULTS: In men, short-term and cumulative-and to a lesser extent lagged-associations of four labour-intensity factors with MDD/GAD occurrence were observed (high volume of work, pressure at work, high complexity, and long working hours). In women, the short-term and cumulative associations of five PSF were observed, mostly emotional demand factors, lack of reward and work-family imbalance. Job insecurity had strong, short-term, cumulative and lagged associations in both men and women. CONCLUSION: According to PSF and gender, the results suggest that the relationships between PSF exposure and MDD/GAD were mostly short-term and cumulative rather than lagged.

Bladder cancer and occupational exposure to metalworking fluid mist: a counter-matched case-control study in French steel-producing factories.

OBJECTIVES: To assess the relationship between occupational exposure to metalworking fluids (MWFs) in the steel-producing industry and bladder cancer incidence. METHODS: A nested case-control study on bladder cancer was set up in a cohort of workers from six French steel-producing factories. Three controls were randomly selected for each incident bladder cancer case diagnosed from 2006 to 2012. Controls were matched to cases on age at diagnosis and counter-matched on a surrogate measure of exposure to MWFs derived from a job-exposure matrix. Cases (n=84) and controls (n=251) were face-to-face interviewed. Experts assessed occupational exposure to MWFs (straight, soluble and synthetic) using questionnaires and reports from factory visits. Occupational exposures were based on three metrics: duration, frequency-weighted duration and cumulative exposure index. Conditional multiple logistic regressions were used to determine ORs and 95% CIs, taking non-occupational and occupational exposure into account. RESULTS: In the 25 years before diagnosis, ORs increased significantly with duration of exposure to straight MWFs (OR=1.13 (1.02-1.25)) and increased with frequency-weighted duration of exposure to straight MWFs (OR=1.44 (0.97-2.14)). These results remained valid after adjusting for duration of smoking, average number of cigarettes smoked per day, time since smoking cessation and exposure to polycyclic aromatic hydrocarbons (PAHs). ORs also increased with soluble MWFs but not significantly. No significant association was found with older exposures to MWFs or with exposure to synthetic MWFs. CONCLUSION: The increased risk of bladder cancer observed among workers exposed to straight MWFs and to a lesser extent to soluble MWFs may be explained by the presence of carcinogens (such as PAH) in mineral oils component of straight and soluble oils. Prevention therefore remains necessary in sectors using MWFs.

Effect of occupational safety and health education received during schooling on the incidence of workplace injuries in the first 2 years of occupational life: a prospective study.

OBJECTIVES: This study aimed to determine the effect of occupational safety and health (OSH) education during formal schooling on the incidence of workplace injuries (WIs) in young people starting their careers. We hypothesised that young people who had received OSH education during their schooling would have fewer WIs than those who received no OSH education. Secondary objectives focused on the effect of 'first aid at work' training during schooling and the conditions encountered on arrival in the company (occupational hazard information, safety training and job task training) on WI occurrence. DESIGN: Prospective cohort study. PARTICIPANTS: From 2009 to 2012, French apprentices and students at the end of their schooling and starting their careers were included. OUTCOMES: Occurrence of WIs. METHODS: At the time of inclusion, information about school courses and personal characteristics were collected, and subsequent half-yearly contacts gathered information relating to work and personal data. During the 2-year follow-up, WIs were directly reported by participants and were identified by searching the French National Health Insurance Funds' databases listing compulsory WI declarations. RESULTS: 755 participants reported holding 1290 jobs. During follow-up, 158 WIs were identified, corresponding to an incident rate of 0.12 (0.10 to 0.14) WIs per full-time worker. Subjects who reported having received OSH education at school had two times less WIs than those declaring not having received OSH education (incidence rate ratio (IRR) 0.51, 0.00 to 0.98). A lower WI risk was observed for participants who received the 'first aid at work' training (IRR=0.68, 0.00 to 0.98). The conditions on arrival in company were not associated with WIs occurrence. CONCLUSION: In France, the OSH education provided to apprentices and students is mostly broader than the specific risks related to future jobs. Our results highlight the advantages of reinforcing this approach.

Geographical Heterogeneity of Multiple Sclerosis Prevalence in France.

INTRODUCTION: Geographical variation in the prevalence of multiple sclerosis (MS) is controversial. Heterogeneity is important to acknowledge to adapt the provision of care within the healthcare system. We aimed to investigate differences in prevalence of MS in departments in the French territory. METHODS: We estimated MS prevalence on October 31, 2004 in 21 administrative departments in France (22% of the metropolitan departments) by using multiple data sources: the main French health insurance systems, neurologist networks devoted to MS and the Technical Information Agency of Hospitalization. We used a spatial Bayesian approach based on estimating the number of MS cases from 2005 and 2008 capture-recapture studies to analyze differences in prevalence. RESULTS: The age- and sex-standardized prevalence of MS per 100,000 inhabitants ranged from 68.1 (95% credible interval 54.6, 84.4) in Hautes-Pyrénées (southwest France) to 296.5 (258.8, 338.9) in Moselle (northeast France). The greatest prevalence was in the northeast departments, and the other departments showed great variability. DISCUSSION: By combining multiple data sources into a spatial Bayesian model, we found heterogeneity in MS prevalence among the 21 departments of France, some with higher prevalence than anticipated from previous publications. No clear explanation related to health insurance coverage and hospital facilities can be advanced. Population migration, socioeconomic status of the population studied and environmental effects are suspected.

Effects of occupational exposure to poorly soluble forms of beryllium on biomarkers of pulmonary response in exhaled breath of workers in machining industries.

OBJECTIVE: To analyze the effects of occupational exposure to poorly soluble forms of beryllium (Be) on biomarkers of pulmonary inflammation using exhaled breath condensate (EBC) in workers employed in machining industries. METHODS: Twenty machining operators were compared to 16 controls. The individual exposure to Be was assessed from the work history with several indices of exposure calculated on the basis of task-exposures matrices developed for each plant using historical air measurements. Clinical evaluation consisted in a medical questionnaire, measurements of biomarkers in EBC (tumor necrosis factor alpha (TNF-α), total nitrogen oxides (NOx)), measurement of the fraction of exhaled nitric oxide (FeNO) and resting spirometry. Adjusted multiple linear regressions were used to study the effect of the exposure to Be on inflammatory biomarkers. RESULTS: Levels of TNF-α and NOx in EBC were not statistically different between exposed and controls. We found a statistically significant relationship between levels of TNF-α in EBC and both index of cumulative exposure and duration of exposure to Be. No other statistically significant relationships were found between exposure to Be and pulmonary response. CONCLUSION: Our results suggest that machining-related exposure to Be is related to pulmonary inflammation involving TNF-α. These findings must be confirmed by larger studies.

Beryllium in exhaled breath condensate as a biomarker of occupational exposure in a primary aluminum production plant.

OBJECTIVE: Low beryllium exposure can induce pulmonary granulomatosis, so called berylliosis. For occupational health monitoring, it is more relevant to assess the internal dose of Be received by the lungs than urinary or atmospheric Be. Exhaled breath condensate (EBC) is a matrix collected non-invasively that derives from the airway lining fluid. EBC beryllium (Be) levels were evaluated as a marker of occupational exposure in a primary aluminum production plant. METHODS: We collected urine and EBC from controls and workers recently exposed to beryllium in the pot room and the anode repair sectors, and calculated a cumulative beryllium exposure index (CBEI) summing the number of years of employment in each task and multiplying by the estimated average beryllium exposure for the task. Concentrations of beryllium and aluminum were measured in EBC (Be-EBC and Al-EBC) and in urine (Be-U and Al-U) by ICP-MS. RESULTS AND CONCLUSION: We have shown that it was possible to measure Be and Al in workers' EBC. Compared with controls and after adjustment for smoking status, levels of Be-EBC and Al-EBC were higher in pot room workers and exposed subjects, respectively. Due to its relationship with CBEI, but not with Be-U, it appears that Be-EBC could be a promising marker of occupational exposure and provide additional toxicokinetic information in occupational health studies.

Effects of chronic low-dose exposure to ionizing radiation on physician microvascular structure revealed by nail fold capillaroscopy.

The aim of this study was to assess the long-term asymptomatic effects of low-dose radiation on microvascular structure among interventional physicians, whose hands are exposed to ionizing radiation during daily practice. The study, approved by the national ethics committee, included 186 radiation-exposed (surgeons, cardiologists, radiologists) and 35 unexposed physicians, all of whom had provided written consent. The subjects completed a questionnaire describing their current and past daily practice, from which tentative estimates of current and cumulative radiation exposure estimates were computed. Subject dermal microcirculation state was assessed by capillaroscopy of the nail fold of eight fingers (thumbs excluded) based on photographs. Two quantitative scores characterizing extravasation and morphological abnormalities based on seven semiquantitative indices were obtained from post hoc coding of the photographs by five capillaroscopists. These evaluations were randomized and blind to the exposure. The effect of the radiation exposure on both abnormality scores was modelled using multilevel proportional odds regression adjusted for potential confounders. The proportion of physicians for which the most frequent act is close to the radiation source was highest among surgeons, but with fewer weekly acts. The median duration of exposure was highest among radiologists and cardiologists. No exposure effect could be detected on the extravasation score. The morphological anomaly score increased significantly with duration of exposure and estimated cumulative exposure among surgeons and interventional radiologists, unlike cardiologists among whom no effect could be detected. It is concluded that the shown effects of chronic low-dose exposure to ionizing radiation on physician microvascular structure reveal the importance of increased exposure monitoring and prevention.

Manufactured nano-objects: an occupational survey in five industries in France.

Manufactured nano-objects (MNO) are being increasingly used in industry, and, given their particular properties, it is therefore necessary to assess the risks linked to their production and use in industrial settings. We describe a survey conducted in France, in five industries concerned with the production of inks, paints, plastics, and the production of raw nano materials. In 2009, a questionnaire was posted to each of the 993 French establishments in these industries. Of the 464 (47%) establishments that responded, 87 indicated that they were producing or using MNO at that time. The results reveal that in the five industries, MNO are generally produced in large quantities by a small number of establishments but are used in smaller amounts by a greater number of establishments. The population of workers exposed to MNO in user establishments is estimated to be ~3000 in the industries surveyed. The protective measures implemented in establishments producing or using MNO differ according to the scale of production and/or use and are sometimes inadequate given the nature of the potential risks. It is therefore necessary to inform users of the presence of MNO in raw materials (through labelling and material safety data sheets MSDS) and to make recommendations as to the collective protective measures that should be implemented.

Producing samples for the organization of proficiency tests. Study of the homogeneity of replicas produced from two atmosphere generation systems.

This article describes two atmosphere generation systems used for the production of replicas. The first, the Sputnic system, is based on the Sputnic air sampler developed by the National Institute of Occupational Health in Oslo (Norway). It is used to generate asbestos fibres or silica particles and allows the simultaneous production, by means of sampling on filters, of up to 114 replicas. The second is a multipurpose system that allows dust sampling on foams used with the CIP 10-R device. Twenty samples can be taken simultaneously. In total, 120 series of samples allowed characterization of the variability of the two generation systems used for the production of replicas loaded with asbestos fibres or silica dust. The coefficients of variation characterizing the dispersion of the filter loading in the Sputnic system are <10% for high densities asbestos fibre or silica dust samples. The coefficient of dispersion is on average higher when the asbestos fibre density is lower. The differences observed between the measurements taken on the different crowns of the Sputnic system are low and <2%. The results obtained with the multipurpose system show that replica dispersion is on average equal to 4%, which will allow proposal in the near future of a proficiency test dedicated to the quantitative analysis of crystalline silica on foams sampled with the CIP 10-R device.

Site comparison of selected aerosol samplers in the wood industry.

Several samplers (IOM, CIP 10-I v1, ACCU-CAP, and Button) were evaluated at various wood industry companies using the CALTOOL system. The results obtained show that compared to the CALTOOL mouth, which can be considered to be representative of the exposure of a person placed at the same location under the same experimental conditions, the concentrations measured by the IOM, CIP 10-I v1, and ACCU-CAP samplers are not significantly different (respectively, 1.12, 0.94, and 0.80 compared to 1.00), the Button sampler (0.86) being close to the ACCU-CAP sampler. Comparisons of dust concentrations measured using both a closed-face cassette (CFC) and one of the above samplers were also made. In all, 235 sampling pairs (sampler + CFC) taken at six companies provided us with a comparison of concentrations measured using IOM, CIP 10-I v1, ACCU-CAP, and Button samplers with concentrations measured using a CFC. All the studied samplers collected systematically more dust than the CFC (2.0 times more for the IOM sampler, 1.84 times more for the CIP 10-I v1 sampler, 1.68 times more for the ACCU-CAP sampler, and 1.46 times more for the Button sampler). The literature most frequently compares the IOM sampler with the CFC: published results generally show larger differences compared with the CFC than those found during our research. There are several explanations for this difference, one of which involves CFC orientation during sampling. It has been shown that concentrations measured using a CFC are dependent on its orientation. Different CFC positions from one sampling session to another are therefore likely to cause differences during CFC-IOM sampler comparisons.

Occupational exposure to inhalable wood dust in the member states of the European Union.

The aim of this study was to estimate occupational exposure to inhalable wood dust by country, industry, the level of exposure and type of wood dust in 25 member states of the European Union (EU-25) for the purposes of hazard control, exposure surveillance and assessment of health risks. National labour force statistics, a country questionnaire (in 15 member states, EU-15), a company survey (in Finland, France, Germany and Spain), exposure measurements (from Denmark, Finland, France, Germany, The Netherlands and the United Kingdom) and expert judgements were used to generate preliminary estimates of exposure to different types of wood dust. The estimates were generated according to industrial class (six wood industries, four other sectors) and level of exposure (five classes). These estimates were reviewed and finalized by national experts from 15 member states. Crude estimates were generated also for 10 new member states (EU-10). The basic data and final estimates were included in the WOODEX database. In 2000-2003, about 3.6 million workers (2.0% of the employed EU-25 population) were occupationally exposed to inhalable wood dust. Of those, construction employed 1.2 million exposed workers (33%), mostly construction carpenters. The numbers of exposed workers were 700,000 (20%) in the furniture industry, 300,000 (9%) in the manufacture of builders' carpentry, 200,000 (5%) in sawmilling, 150,000 (4%) in forestry and <100,000 in other wood industries. In addition, there were 700,000 exposed workers (20%) in miscellaneous industries employing carpenters, joiners and other woodworkers. The numbers of exposed workers varied by country ranging from <3,000 in Luxembourg and Malta to 700,000 in Germany. The highest exposure levels were estimated to occur in the construction sector and furniture industry. Due to limited exposure data there was considerable uncertainty in the estimates concerning construction woodworkers. About 560,000 workers (16% of the exposed) may be exposed to a level exceeding 5 mg m(-3). Mixed exposure to more than one species of wood and dust from wooden boards was very common, but reliable data on exposure to different species of wood could not be retrieved. This kind of assessment procedure integrating measurement data, company data, country-specific data and expert judgement could also serve as one model for the assessment of other occupational exposures.

Confidence intervals for the mean of sound exposure levels.

This text transposes standard statistical estimators of the mean and its confidence intervals to the field of occupational noise exposure, assuming that the samples are independent and lognormally distributed. The hypothesis of lognormality is applied to the values of A-weighted sound exposure as defined in ISO 1999 and expressed in Pa(2).h, which is equivalent to the currently accepted hypothesis of normality applied to the values of equivalent continuous A-weighted sound pressure level L(Aeq,T) expressed in dB(A). By expressing the initial data and results in dB(A), the text provides an unbiased estimator of the mean sound exposure level and tables of confidence intervals according to the sample size n and the standard deviation S(L) of the L(Aeq,T) measured values. The values of the following confidence intervals are given: exact one-sided upper and lower 95 and 97.5% confidence intervals and exact two-sided symmetrical 95% confidence interval. These results are compared with the approximate two-sided symmetrical 95% confidence interval proposed in standard, ISO 9612. This comparison demonstrates that the use of the approximate confidence interval can markedly underestimate the upper limit of the confidence interval when n is small and if S(L) is above 3 dB(A).