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.

Exposure to noise and ototoxic chemicals in the Australian workforce.

OBJECTIVE: To determine the current prevalence of exposure to workplace noise and ototoxic chemicals, including co-exposures. METHOD: A cross-sectional telephone survey of nearly 5000 Australian workers was conducted using the web-based application, OccIDEAS. Participants were asked about workplace tasks they performed and predefined algorithms automatically assessed worker's likelihood of exposure to 10 known ototoxic chemicals as well as estimated their full shift noise exposure level (LAeq,8h) of their most recent working day. Results were extrapolated to represent the Australian working population using a raked weighting technique. RESULTS: In the Australian workforce, 19.5% of men and 2.8% of women exceeded the recommended full shift noise limit of 85 dBA during their last working day. Men were more likely to be exposed to noise if they were younger, had trade qualifications and did not live in a major city. Men were more likely exposed to workplace ototoxic chemicals (57.3%) than women (25.3%). Over 80% of workers who exceeded the full shift noise limit were also exposed to at least one ototoxic chemical in their workplace. CONCLUSION: The results demonstrate that exposures to hazardous noise and ototoxic chemicals are widespread in Australian workplaces and co-exposure is common. Occupational exposure occurs predominantly for men and could explain some of the discrepancies in hearing loss prevalence between genders.

The effects of ambient temperatures on the risk of work-related injuries and illnesses: Evidence from Adelaide, Australia 2003-2013.

BACKGROUND: The thermal environment can directly affect workers' occupational health and safety, and act as a contributing factor to injury or illness. However, the literature addressing risks posed by varying temperatures on work-related injuries and illnesses is limited. OBJECTIVES: To examine the occupational injury and illness risk profiles for hot and cold conditions. METHODS: Daily numbers of workers' compensation claims in Adelaide, South Australia from 2003 to 2013 (n = 224,631) were sourced together with daily weather data. The impacts of maximum daily temperature on the risk of work-related injuries and illnesses was assessed using a time-stratified case-crossover study design combined with a distributed lag non-linear model. RESULTS: The minimum number of workers' compensation claims occurred when the maximum daily temperature was 25 °C. Compared with this optimal temperature, extremely hot temperatures (99th percentile) were associated with an increase in overall claims (RR: 1.30, 95%CI: 1.18-1.44) whereas a non-significant increase was observed with extremely cold temperatures (1st percentile, RR: 1.10 (95%CI: 0.99-1.21). Heat exposure had an acute effect on workers' injuries whereas cold conditions resulted in delayed effects. Moderate temperatures were associated with a greater injury burden than extreme temperatures. CONCLUSION: Days of very high temperatures were associated with the greatest risks of occupational injuries; whereas moderate temperatures, which occur more commonly, have the greatest burden. These findings suggest that the broader range of thermal conditions should be considered in workplace injury and illness prevention strategies.

Satellite-Based Land-Use Regression for Continental-Scale Long-Term Ambient PM2.5 Exposure Assessment in Australia.

Australia has relatively diverse sources and low concentrations of ambient fine particulate matter (<2.5 µm, PM2.5). Few comparable regions are available to evaluate the utility of continental-scale land-use regression (LUR) models including global geophysical estimates of PM2.5, derived by relating satellite-observed aerosol optical depth to ground-level PM2.5 ("SAT-PM2.5"). We aimed to determine the validity of such satellite-based LUR models for PM2.5 in Australia. We used global SAT-PM2.5 estimates (∼10 km grid) and local land-use predictors to develop four LUR models for year-2015 (two satellite-based, two nonsatellite-based). We evaluated model performance at 51 independent monitoring sites not used for model development. An LUR model that included the SAT-PM2.5 predictor variable (and six others) explained the most spatial variability in PM2.5 (adjusted R2 = 0.63, RMSE (µg/m3 [%]): 0.96 [14%]). Performance decreased modestly when evaluated (evaluation R2 = 0.52, RMSE: 1.15 [16%]). The evaluation R2 of the SAT-PM2.5 estimate alone was 0.26 (RMSE: 3.97 [56%]). SAT-PM2.5 estimates improved LUR model performance, while local land-use predictors increased the utility of global SAT-PM2.5 estimates, including enhanced characterization of within-city gradients. Our findings support the validity of continental-scale satellite-based LUR modeling for PM2.5 exposure assessment in Australia.

Night shift work and breast cancer: a pooled analysis of population-based case-control studies with complete work history.

Night shift work has been suspected to increase breast cancer risk but epidemiological studies have been inconsistent due to heterogeneous assessment of exposure to night work. To overcome this limitation, we pooled data of five population-based case-control studies from Australia, Canada, France, Germany, and Spain into a single harmonized dataset using a common definition of night work including 6093 breast cancer cases and 6933 population controls. The odds ratio for breast cancer in women who ever worked at night for at least 3 h between midnight and 5 a.m. as compared to never night workers was 1.12 (95% CI 1.00-1.25). Among pre-menopausal women, this odds ratio was 1.26 [1.06-1.51], increasing to 1.36 [1.07-1.74] for night shifts ≥ 10 h, 1.80 [1.20-2.71] for work ≥ 3 nights/week, and 2.55 [1.03-6.30] for both duration of night work ≥ 10 years and exposure intensity ≥ 3 nights/week. Breast cancer risk in pre-menopausal women was higher in current or recent night workers (OR = 1.41 [1.06-1.88]) than in those who had stopped night work more than 2 years ago. Breast cancer in post-menopausal women was not associated with night work whatever the exposure metric. The increase in risk was restricted to ER+ tumors, particularly those who were both ER+ and HER2+ . These results support the hypothesis that night shift work increases the risk of breast cancer in pre-menopausal women, particularly those with high intensity and long duration of exposure. Risk difference between pre- and post-menopausal women deserves further scrutiny.

Questionnaire-based algorithm for assessing occupational noise exposure of construction workers.

OBJECTIVES: Occupational noise exposure is a major cause of hearing loss worldwide. In order to inform preventative strategies, we need to further understand at a population level which workers are most at risk. METHODS: We have developed a new questionnaire-based algorithm that evaluates an individual worker's noise exposure. The questionnaire and supporting algorithms are embedded into the existing software platform, OccIDEAS. Based on the tasks performed by a worker during their most recent working shift and using a library of task-based noise exposure levels, OccIDEAS estimates whether a worker has exceeded the full-shift workplace noise exposure limit (LAeq,8h≥85 dBA). We evaluated the validity of the system in a sample of 100 construction workers. Each worker wore a dosimeter for a full working shift and was then interviewed using the OccIDEAS software. RESULTS: The area under the receiver operating characteristic curve was 0.81 (95% CI 0.72 to 0.90) indicating that the ability of OccIDEAS to identify construction workers with an LAeq,8h≥85 dBA was excellent. CONCLUSION: This validated noise questionnaire may be useful in epidemiological studies and for workplace health and safety applications.

Shift work that involves circadian disruption and breast cancer: a first application of chronobiological theory and the consequent challenges.

OBJECTIVES: In 2007, the International Agency for Research on Cancer classified shift work involving circadian disruption (CD) as probably carcinogenic to humans. Circadian disruption could be conceptualised as the overlap of activity, such as work, with an individual's biological night. The latter can be approximated from a worker's chronotype (or morning/evening preference). Few previous studies have taken chronotype into account when assessing CD caused by shift work. Our objective was to test the hypothesis that women working during their biological night would be at increased risk of breast cancer. METHODS: We used data from our case-control study of breast cancer to investigate associations between shift work involving CD and breast cancer risks. Previously, we had assumed that everyone working in jobs which involved work for two or more shifts between midnight and 05:00 hours was equally exposed to CD. In the present analyses, we reclassified as unexposed those who had a late chronotype in which their preferred bedtime was 2 hours after the end of their shift. RESULTS: Only 30 of 1385 night jobs changed classification and the overall finding (OR 1.17, 95% CI 0.98 to 1.41) was not different to the original finding when chronotype was not considered. CONCLUSIONS: We found virtually no difference between our new and old classifications of exposure. However, we were not able to calculate the total number of chronodisrupted shifts over a lifetime in order to assess dose and nor were we able to determine how many women were exposed to CD when doing shifts which began before midnight. Our first practical application highlights challenges for future chronobiology-based research.

Association between shiftwork and the risk of colorectal cancer in females: a population-based case-control study.

OBJECTIVE: Research indicates that shiftwork may be associated with increased risks of adverse health outcomes, including some cancers. However, the evidence of an association between shiftwork and colorectal cancer risk is limited and inconclusive. Further, while several possible pathways through which shiftwork might result in cancer have been proposed, few studies have taken these factors into account. We investigated the association between two types of shiftwork (graveyard shiftwork and early-morning shiftwork) and six mechanistic shiftwork variables (including light at night and phase shift) and the risk of colorectal cancer among females in an Australian population-based case-control study. Graveyard shiftwork was the primary exposure of interest. METHODS: Participants (350 cases and 410 controls) completed a lifetime occupational history, and exposure to each of the eight shiftwork variables was assigned to participants through a job exposure matrix. We used logistic regression to calculate odds ratios (OR) and corresponding 95% confidence intervals (CI) for the association between different shiftwork variables and the risk of colorectal cancer, adjusting for potential demographic, lifestyle and medical confounders. RESULTS: Working in an occupation involving long-term exposure (>7.5 years) to graveyard shiftwork was not associated with colorectal cancer risk (adjusted OR 0.95, 95% CI 0.57 to 1.58). Similarly, no increased risks of colorectal cancer were seen for any of the other seven shiftwork variables examined. CONCLUSIONS: No evidence of an increased risk of colorectal cancer among females who had worked in occupations involving shiftwork was observed in this study.

Blending Multiple Nitrogen Dioxide Data Sources for Neighborhood Estimates of Long-Term Exposure for Health Research.

Exposure to traffic related nitrogen dioxide (NO2) air pollution is associated with adverse health outcomes. Average pollutant concentrations for fixed monitoring sites are often used to estimate exposures for health studies, however these can be imprecise due to difficulty and cost of spatial modeling at the resolution of neighborhoods (e.g., a scale of tens of meters) rather than at a coarse scale (around several kilometers). The objective of this study was to derive improved estimates of neighborhood NO2 concentrations by blending measurements with modeled predictions in Sydney, Australia (a low pollution environment). We implemented the Bayesian maximum entropy approach to blend data with uncertainty defined using informative priors. We compiled NO2 data from fixed-site monitors, chemical transport models, and satellite-based land use regression models to estimate neighborhood annual average NO2. The spatial model produced a posterior probability density function of estimated annual average concentrations that spanned an order of magnitude from 3 to 35 ppb. Validation using independent data showed improvement, with root mean squared error improvement of 6% compared with the land use regression model and 16% over the chemical transport model. These estimates will be used in studies of health effects and should minimize misclassification bias.

Australian work exposures studies: occupational exposure to pesticides.

BACKGROUND: Pesticides are widely used in some occupational settings. Some pesticides have been classified as carcinogens; however, data on the number of workers exposed to pesticides are not available in Australia. The main aim of this study was to estimate the current prevalence of pesticide exposure in Australian workplaces. METHODS: The analysis used data from the Australian Work Exposures Study, a series of nationwide telephone surveys which investigated work-related prevalence and exposure to carcinogens and asthmagens, including pesticides, among current Australian workers. Information about the respondents' current job and various demographic factors was collected in a telephone interview using the web-based tool OccIDEAS. Workers were considered exposed to pesticides if they reported applying or mixing pesticides in their current job. RESULTS: Of the 10 371 respondents, 410 (4%) respondents were assessed as being exposed to pesticides in the workplace, with exposure being more likely among males, individuals born in Australia, individuals with lower education level and those residing in regional or remote areas. Glyphosate was the most common active ingredient used by workers. CONCLUSIONS: This is the first study to describe the prevalence of occupational pesticide exposure in Australia and one of the few recent studies internationally.

Independent Validation of National Satellite-Based Land-Use Regression Models for Nitrogen Dioxide Using Passive Samplers.

Including satellite observations of nitrogen dioxide (NO2) in land-use regression (LUR) models can improve their predictive ability, but requires rigorous evaluation. We used 123 passive NO2 samplers sited to capture within-city and near-road variability in two Australian cities (Sydney and Perth) to assess the validity of annual mean NO2 estimates from existing national satellite-based LUR models (developed with 68 regulatory monitors). The samplers spanned roadside, urban near traffic (≤100 m to a major road), and urban background (>100 m to a major road) locations. We evaluated model performance using R2 (predicted NO2 regressed on independent measurements of NO2), mean-square-error R2 (MSE-R2), RMSE, and bias. Our models captured up to 69% of spatial variability in NO2 at urban near-traffic and urban background locations, and up to 58% of variability at all validation sites, including roadside locations. The absolute agreement of measurements and predictions (measured by MSE-R2) was similar to their correlation (measured by R2). Few previous studies have performed independent evaluations of national satellite-based LUR models, and there is little information on the performance of models developed with a small number of NO2 monitors. We have demonstrated that such models are a valid approach for estimating NO2 exposures in Australian cities.

Sedentary work and the risk of breast cancer in premenopausal and postmenopausal women: a pooled analysis of two case-control studies.

OBJECTIVES: There is limited research on the association between sedentary behaviour and breast cancer risk, particularly whether sedentary behaviour is differentially associated with premenopausal and postmenopausal breast cancer. We pooled data from 2 case-control studies from Australia and Canada to investigate this association. METHODS: This pooled analysis included 1762 incident breast cancer cases and 2532 controls. Participants in both studies completed a lifetime occupational history and self-rated occupational physical activity level. A job-exposure matrix (JEM) was also applied to job titles to assess sedentary work. Logistic regression analyses (6 pooled and 12 study-specific) were conducted to estimate associations between both self-reported and JEM-assessed sedentary work and breast cancer risk among premenopausal and postmenopausal women. RESULTS: No association was observed in the 6 pooled analyses, and 10 of the study-specific analyses also showed null results. 2 study-specific analyses provided inconsistent and contradictory results, with 1 showing statistically significant increased risk of breast cancer for self-reported sedentary work among premenopausal women cancer in the Canadian study, and the other a non-significant inverse association between JEM-assessed sedentary work and breast cancer risk among postmenopausal women in the Australian study. CONCLUSIONS: While a suggestion of increased risk was seen for premenopausal women in the Canadian study when using the self-reported measure, overall this pooled study does not provide evidence that sedentary work is associated with breast cancer risk.

Occupational exposures to engine exhausts and other PAHs and breast cancer risk: A population-based case-control study.

BACKGROUND: Some previous studies have suggested that exposure to engine exhausts may increase risk of breast cancer. METHODS: In a population-based case-control study of breast cancer in Western Australia we assessed occupational exposure to engine exhausts using questionnaires and telephone interviews. Odds Ratios (OR) and 95% Confidence Intervals (CI) were calculated using logistic regression. RESULTS: We found no association between risk of breast cancer and occupational exposure to diesel exhaust (OR 1.07, 95%CI: 0.81-1.41), gasoline exhaust (OR 0.98, 95%CI: 0.74-1.28), or other exhausts (OR 1.08, 95%CI: 0.29-4.08). There were also no significant dose- or duration-response relationships. CONCLUSIONS: This study did not find evidence supporting the association between occupational exposures to engine exhausts and breast cancer risk. Am. J. Ind. Med. 59:437-444, 2016. © 2016 Wiley Periodicals, Inc.

Smoking, alcohol, diabetes, obesity, socioeconomic status, and the risk of colorectal cancer in a population-based case-control study.

PURPOSE: Although previous research has identified factors that may determine willingness to participate in research, relatively few studies have attempted to quantify the impact non-participation may have on exposure-disease associations. The aims of this study were to (a) investigate the associations between smoking, alcohol, diabetes, obesity, and socioeconomic status and the risk of colorectal cancer in a case-control study (59.7 and 47.2 % response fractions among cases and controls, respectively); and (b) perform sensitivity analyses to examine the possible influence of non-participation. METHODS: Logistic regression was used to estimate the exposure-disease associations. We then investigated the associations between various demographic and health factors and the likelihood that an individual would participate in the case-control study and then performed two sensitivity analyses (sampling weights and multiple imputation) to examine whether non-participation bias may have influenced the exposure-disease associations. RESULTS: The exposures alcohol, smoking, and diabetes were associated with an increased risk of colorectal cancer. We found some differences between cases and controls when examining the factors associated with the participation in the study, and in the sensitivity analyses, the exposure-disease associations were slightly attenuated when compared with those from the original analysis. CONCLUSION: Non-participation may have biased the risk estimates away from the null, but generally not enough to change the conclusions of the study.

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.

The association of circadian parameters and the clustering of fatigue, depression, and sleep problems in breast cancer survivors: a latent class analysis.

PURPOSE: Circadian rhythms control a wide range of physiological processes and may be associated with fatigue, depression, and sleep problems. We aimed to identify subgroups of breast cancer survivors based on symptoms of fatigue, insomnia, and depression; and assess whether circadian parameters (i.e., chronotype, amplitude, and stability) were associated with these subgroups over time. METHODS: Among breast cancer survivors, usual circadian parameters were assessed at 3-4 months after diagnosis (T0), and symptoms of fatigue, depression, and insomnia were assessed after 2-3 years (T1, N = 265) and 6-8 years (T2, N = 169). We applied latent class analysis to classify survivors in unobserved groups ("classes") based on symptoms at T1. The impact of each of the circadian parameters on class allocation was assessed using multinomial logistic regression analysis, and changes in class allocation from T1 to T2 using latent transition models. RESULTS: We identified 3 latent classes of symptom burden: low (38%), moderate (41%), and high (21%). Survivors with a late chronotype ("evening types") or low circadian amplitude ("languid types") were more likely to have moderate or high symptom burden compared to "morning types" and "vigorous types," respectively. The majority of survivors with moderate (59%) or high (64%) symptom burden at T1 had persistent symptom burden at T2. IMPLICATIONS FOR CANCER SURVIVORS: A late chronotype and lower circadian amplitude after breast cancer diagnosis were associated with greater symptoms of fatigue, depression, and insomnia at follow-up. These circadian parameters may potentially be novel targets in interventions aimed at alleviating symptom burden among breast cancer survivors.

Long-term exposure to low-concentration PM2.5 and heart disease in older men in Perth, Australia: The Health in Men Study.

Exposure to particulate matter with an aerodynamic diameter less than or equal to 2.5 µm (PM2.5) is associated with increased risk of heart disease, but less is known about the relationship at low concentrations. This study aimed to determine the dose-response relationship between long-term PM2.5 exposure and risk of incident ischemic heart disease (IHD), incident heart failure (HF), and incident atrial fibrillation (AF) in older men living in a region with relatively low ambient air pollution. Methods: PM2.5 exposure was estimated for 11,249 older adult males who resided in Perth, Western Australia and were recruited from 1996 to 1999. Participants were followed until 2018 for the HF and AF outcomes, and until 2017 for IHD. Cox-proportional hazards models, using age as the analysis time, and adjusting for demographic and lifestyle factors were used. PM2.5 was entered as a restricted cubic spline to model nonlinearity. Results: We observed a mean PM2.5 concentration of 4.95 µg/m3 (SD 1.68 µg/m3) in the first year of recruitment. After excluding participants with preexisting disease and adjusting for demographic and lifestyle factors, PM2.5 exposure was associated with a trend toward increased incidence of IHD, HF, and AF, but none were statistically significant. At a PM2.5 concentration of 7 µg/m3 the hazard ratio for incident IHD was 1.04 (95% confidence interval [CI] = 0.86, 1.25) compared with the reference category of 1 µg/m3. Conclusions: We did not observe a significant association between long-term exposure to low-concentration PM2.5 air pollution and IHD, HF, or AF.

Dietary and supplemental folate and the risk of left- and right-sided colorectal cancer.

Epidemiological evidence suggests that folate may lower the risk of colorectal cancer (CRC) although studies have been inconsistent and some have indicated differences in the effects of naturally occurring dietary folate and the synthetic form of this vitamin, folic acid. Most studies to date have considered CRC as a single disease; however, cancers that develop on the left and right sides of the colorectum display important phenotypic differences, suggesting they may also have different risk factors. A population-based case-control study was conducted in Western Australia to examine the relationship between intake of both natural dietary folate and supplements containing folic acid and the risk of left- and right-sided CRC. Data were available for 850 cases (575 left-sided and 275 right-sided) and 958 controls. Odds ratios were calculated using multinomial logistic regression models. There was no association between natural dietary folate intake and risk of either left-or right-sided CRC. Supplement use similarly had no significant effect on right-sided CRC. However, long-term supplement users (4+ yr) were at lower risk of left-sided CRC than those who had not taken supplements (OR = 0.65, 95% CI, 0.50-0.86) and there was a significant trend in risk reduction as duration of use increased (P < 0.01).

Prenatal exposure to mixtures of persistent environmental chemicals and fetal growth outcomes in Western Australia.

BACKGROUND: Environmental chemicals have been implicated in the etiology of impaired fetal growth. However, few studies have assessed the effects of chemical mixtures or considered the possibility of non-monotonic exposure-response relationships for chemicals that act through the endocrine system. METHODS: We assessed exposure to polybrominated diphenyl ethers, organochlorine pesticides, metals, and perfluorinated alkyl substances in blood and urine samples collected approximately two weeks prior to delivery in 166 non-smoking pregnant women, and subsequent birth weight, length, and head circumference of neonates who were part of the Australian Maternal Exposures to Toxic Substances (AMETS) study. We used Bayesian structured additive regression models with spike-slab priors to estimate mixture effects, identify important exposures, and model non-linearity in exposure-response relationships. RESULTS: Mixtures of polybrominated diphenyl ethers, organochlorine pesticides, metals, and perfluorinated alkyl substances were not associated with fetal growth outcomes. Estimated change in fetal growth outcomes for an increase in exposure from the 25th to 75th percentile suggested no meaningful associations; the strongest evidence was for a small inverse association between birth weight and cesium exposure measured in whole blood (-124 g, 90% credible interval: -240 to -3 g). We identified several chemicals that may be associated with fetal growth non-linearly; however, 90% credible intervals contained small values consistent with no meaningful association. CONCLUSIONS: Using a Bayesian penalized regression method, we assessed the shapes of exposure-response relationships, controlled for confounding by co-exposure, and estimated the single and combined effects of a large mixture of correlated environmental chemicals on fetal growth. Our findings, based on a small sample of mother-neonate pairs, suggest that mixtures of persistent chemicals are not associated with birth weight, length, and head circumference. The potential for non-monotonic relationships between environmental chemicals and fetal growth outcomes warrants further study.

Exposure to Hand-Arm Vibration in the Australian Workforce.

OBJECTIVE: To estimate the prevalence of hand-arm vibration (HAV) in Australian workplaces. METHODS: The Australian Workplace Exposure Survey (AWES)-Hearing was a cross-sectional telephone survey of Australian workers conducted in 2016-2017. Respondents were asked about the time spent using tools or performing tasks known to be associated with HAV during their most recent working day. We created a library of HAV magnitude levels for each tool/task and estimated each worker's daily HAV exposure level using standard formulae. We categorized each worker as to whether they exceeded the daily occupational limits of 2.5 and 5.0 m/s2. Results were extrapolated to the Australian working population using a raked weighting method. RESULTS: In our sample of 4991 workers, 5.4% of men and 0.7% of women exceeded the HAV action limit of 2.5 m/s2 on their most recent working day. We estimate that 3.8% of the Australian workforce exceeds the HAV limit of 2.5 m/s2 and 0.8% exceeds the 5 m/s2 limit. Men were more likely to exceed the HAV limits than women, as were those with trade qualifications, and those who worked in remote locations. Workers in the construction, farming, and automobile industries had the highest prevalence of HAV exposure. Tool groups that contributed to higher exposure levels included: compactors, rollers, and tampers; power hammers and jackhammers; and underground mining equipment. CONCLUSIONS: HAV is common in the Australian working population. Given the health risks associated with this exposure, reduction strategies and interventions should be developed, with engineering controls as the starting point for exposure reduction strategies.