Work-Related Risk Factors for Rotator Cuff Syndrome in a Prospective Study of Manufacturing and Healthcare Workers.

OBJECTIVE: This prospective study assessed the risk of developing rotator cuff syndrome (RCS) with separate or specific combinations of biomechanical exposures measures, controlling for individual confounders. BACKGROUND: Compared with other musculoskeletal disorders, rates of work-related shoulder musculoskeletal disorders have been declining more slowly. METHOD: We conducted up to 2 years of individual, annual assessments of covariates, exposures, and health outcomes for 393 U.S. manufacturing and healthcare workers without RCS at baseline. Task-level biomechanical exposures assessed exposure to forceful exertions (level, exertion rates, duty cycles), vibration, and upper arm postures (flexion, abduction). Hazard ratios (HRs) were calculated with Cox proportional hazard models. RESULTS: We observed 39 incident RCS cases in 694 person-years (incidence rate = 5.62 per 100 person-years). Adjusting for confounders, we found increased risk of incident RCS associated with forceful hand exertions per minute for three upper arm posture tertiles: flexion ≥45° (≥28.2% time, HR = 1.11, CI [1.01, 1.22]), abduction ≥30° (11.9-21.2%-time, HR = 1.18, CI [1.04, 1.34]), and abduction >60° (≥4.8% time, HR = 1.16, CI [1.04, 1.29]). We failed to observe statistically significant effects for other interactions or any separate measures of biomechanical exposure. CONCLUSION: This study highlights the importance of assessing combinations of exposure to forceful repetition and upper arm elevation when developing interventions for preventing RCS. APPLICATION: Based on these results, interventions that reduce exposure to forceful repetition (i.e., lower force levels and/or slower exertion rates) may reduce the risk of RCS, especially when upper arm elevation cannot be avoided.

Noise exposures and perceptions of hearing conservation programs among wildland firefighters.

Wildland firefighters are exposed to numerous noise sources that may be hazardous to their hearing. This study examined the noise exposure profiles for 264 wildland firefighters across 15 job categories. All 264 firefighters completed questionnaires to assess their use of hearing protection devices, enrollment in hearing conservation programs, and their overall perception of their noise exposure. Roughly 54% of firefighters' noise exposures exceeded the National Institute for Occupational Safety and Health recommended exposure limit of 85 decibels, A-weighted, over 8 hr, and 32% exceeded the Occupational Safety and Health Administration permissible exposure limit of 90 decibels, A-weighted, over 8 hr. Questionnaire results indicated good agreement between noise exposures and firefighters' perceptions of the noise hazard. Approximately 65% reported that they used some form of hearing protection; however, only 19% reported receiving any proper training regarding the use of hearing protection devices, with the majority of those firefighters relying on earplugs, including electronic and level-dependent earplugs, over earmuffs or other forms of hearing protectors. The results also suggest that improved communication and situational awareness play a greater role in the consistent use of hearing protection devices than other factors such as risk of developing noise-induced hearing loss. The study highlighted the challenges facing wildland firefighters and their management and the need for a comprehensive wildland fire agencies' hearing conservation program especially for firefighters who were exempt based on their occupational designations.

Inter-laboratory comparison of three earplug fit-test systems.

The National Institute for Occupational Safety and Health (NIOSH) sponsored tests of three earplug fit-test systems (NIOSH HPD Well-Fit, Michael & Associates FitCheck, and Honeywell Safety Products VeriPRO). Each system was compared to laboratory-based real-ear attenuation at threshold (REAT) measurements in a sound field according to ANSI/ASA S12.6-2008 at the NIOSH, Honeywell Safety Products, and Michael & Associates testing laboratories. An identical study was conducted independently at the U.S. Army Aeromedical Research Laboratory (USAARL), which provided their data for inclusion in this article. The Howard Leight Airsoft premolded earplug was tested with twenty subjects at each of the four participating laboratories. The occluded fit of the earplug was maintained during testing with a soundfield-based laboratory REAT system as well as all three headphone-based fit-test systems. The Michael & Associates lab had the highest average A-weighted attenuations and smallest standard deviations. The NIOSH lab had the lowest average attenuations and the largest standard deviations. Differences in octave-band attenuations between each fit-test system and the American National Standards Institute (ANSI) sound field method were calculated (Attenfit-test - AttenANSI). A-weighted attenuations measured with FitCheck and HPD Well-Fit systems demonstrated approximately ±2 dB agreement with the ANSI sound field method, but A-weighted attenuations measured with the VeriPRO system underestimated the ANSI laboratory attenuations. For each of the fit-test systems, the average A-weighted attenuation across the four laboratories was not significantly greater than the average of the ANSI sound field method. Standard deviations for residual attenuation differences were about ±2 dB for FitCheck and HPD Well-Fit compared to ±4 dB for VeriPRO. Individual labs exhibited a range of agreement from less than a dB to as much as 9.4 dB difference with ANSI and REAT estimates. Factors such as the experience of study participants and test administrators, and the fit-test psychometric tasks are suggested as possible contributors to the observed results.

A meta-analysis of studies investigating the effects of occupational lead exposure on thyroid hormones.

INTRODUCTION: Investigations of the effects of occupational exposure to lead on the concentrations of thyroid hormones in the blood have not produced consistent results. A meta-analysis was performed to assess the effect of occupational exposure to lead on thyroid hormone concentrations using the results from published studies. METHODS: Group means from studies of the thyroid function of persons occupationally exposed to lead were used in a meta-analysis. Differences between the control and exposed groups, and the slopes between thyroid hormone concentrations and log10 blood lead concentrations or duration of exposure to lead were estimated using mixed models. The hormones analyzed were thyroid stimulating hormone, total and free thyroxine, and total and free triiodothyronine. RESULTS: No differences in mean thyroid hormone concentrations were found between the exposed and control groups. No relationships were found between blood lead or the duration of exposure to lead and thyroid hormone concentrations. CONCLUSION: The results of the analysis do not provide evidence for an effect of occupational lead exposure on thyroid function in men. Am. J. Ind. Med. 59:583-590, 2016. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Serious injury and fatality investigations involving pneumatic nail guns, 1985-2012.

BACKGROUND: This article examines serious and fatal pneumatic nail gun (PNG) injury investigations for workplace, tool design, and human factors relevant to causation and resulting OS&H authorities' responses in terms of citations and penalties. METHODS: The U.S. Occupational Safety and Health Administration (OSHA) database of Fatality and Catastrophe Investigation Summaries (F&CIS) were reviewed (1985-2012) to identify n = 258 PNG accidents. RESULTS: 79.8% of investigations, and 100% of fatalities, occurred in the construction industry. Between 53-71% of injuries appear to have been preventable had a safer sequential trigger tool been used. Citations and monetary penalties were related to injury severity, body part injured, disabling of safety devices, and insufficient personal protective equipment (PPE). CONCLUSIONS: Differences may exist between construction and other industries in investigators interpretations of PNG injury causation and resulting citations/penalties. Violations of PPE standards were penalized most severely, yet the preventive effect of PPE would likely have been less than that of a safer sequential trigger.

Time-related increase in urinary testosterone levels and stable semen analysis parameters after bariatric surgery in men.

The aim of this prospective cohort study was to determine the time-course in androgen and semen parameters in men after weight loss associated with bariatric surgery. Six men aged 18-40 years, meeting National Institutes of Health bariatric surgery guidelines, were followed between 2005 and 2008. Study visits took place at baseline, then 1, 3, 6 and 12 months after surgery. All men underwent Roux-en-y gastric bypass (RYGB). At each visit, biometric, questionnaire, serum, and urinary specimens and seman analysis were collected. Urinary integrated total testosterone levels increased significantly (P < 0.0001) by 3 months after surgery, and remained elevated throughout the study. Circulating testosterone levels were also higher at 1 and 6 months after surgery, compared with baseline. Serum sex hormone-binding globulin levels were significantly elevated at all time points after surgery (P < 0.01 to P = 0.02). After RYGB surgery, no significant changes occurred in urinary oestrogen metabolites (oestrone 3-glucuronide), serum oestradiol levels, serial semen parameters or male sexual function by questionnaire. A threshold of weight loss is necessary to improve male reproductive function by reversing male hypogonadism, manifested as increased testosterone levels. Further serial semen analyses showed normal ranges for most parameters despite massive weight loss.

Effects of gestational and lactational exposure to heptachlor epoxide on age at puberty and reproductive function in men and women.

BACKGROUND: For 15 months in 1981-1982, the commercial milk supply on the Hawaiian island of Oahu was contaminated with heptachlor epoxide, a metabolite of the insecticide heptachlor, resulting in gestational and/or lactational exposure to offspring of women who drank cow milk during that period. OBJECTIVE: To determine whether gestational and lactational exposure to heptachlor epoxide alters reproductive function and age at puberty in men or women. METHODS: 457 participants were recruited from a prior high school enrollment sampling frame of 20,000 adults born during 1981-1982 who lived on Oahu since at least first grade. Number of glasses of cow milk consumed weekly by the mother during the participant's gestation was used as a surrogate measure of heptachlor epoxide exposure. Reproductive function measures included semen analyses; reproductive hormones or their metabolites in daily urine specimens for one menstrual cycle; serum reproductive hormone levels in both sexes; and reported ages of onset for pubertal milestones. RESULTS: We observed no strong associations of heptachlor epoxide exposure during gestation and lactation with reproductive endpoints. In females, heptachlor epoxide exposure was associated with longer luteal phase length and slower drop in the ratio of estradiol to progesterone metabolites after ovulation. In males, heptachlor epoxide exposure was weakly associated with higher serum follicle stimulating hormone and luteinizing hormone concentrations, but no dose-response relationship was apparent. CONCLUSIONS: The results provide limited evidence that gestational and lactational exposure to heptachlor epoxide, due to milk contamination on Oahu in 1981-1982, resulted in clinically significant disturbances of reproductive function in men or women.

Detection of DNA damage in workers exposed to JP-8 jet fuel.

The genotoxicity of jet propulsion fuel 8 (JP-8) was assessed in the leukocytes of archived blood specimens from U.S. Air Force personnel using the comet assay. No differences in mean comet assay measurements were found between low, moderate, and high exposure groups before or after a 4h work shift. Before the work shift, mean tail DNA and mean tail (Olive) moment increased as the concentration of benzene measured in end-exhaled breath increased, indicating that prior environmental or work-related exposures to benzene produced DNA damage. The number of cells with highly damaged DNA decreased as the pre-shift benzene concentration in breath increased. It is not clear why the decrease is occurring. Mean tail DNA and mean tail (Olive) moment decreased as the concentrations of benzene and naphthalene measured in breath immediately after the work shift increased. These inverse relationships may reflect a slower rate of absorption or a faster rate of expiration of benzene in the lung. The number of cells with highly damaged DNA increased as the concentration of urinary (2-methoxyethoxy)acetic acid (MEAA) increased. This relationship was not seen in urinary MEAA adjusted for creatinine. MEAA is a metabolite of the deicing agent 2-(2-methoxyethoxy)ethanol contained in JP-8. MEAA or a component of JP-8 correlated with MEAA may have a toxic effect on DNA.

Menstrual cycle characteristics and reproductive hormone levels in women exposed to atrazine in drinking water.

Atrazine is the most commonly used herbicide in the U.S. and a wide-spread groundwater contaminant. Epidemiologic and laboratory evidence exists that atrazine disrupts reproductive health and hormone secretion. We examined the relationship between exposure to atrazine in drinking water and menstrual cycle function including reproductive hormone levels. Women 18-40 years old residing in agricultural communities where atrazine is used extensively (Illinois) and sparingly (Vermont) answered a questionnaire (n=102), maintained menstrual cycle diaries (n=67), and provided daily urine samples for analyses of luteinizing hormone (LH), and estradiol and progesterone metabolites (n=35). Markers of exposures included state of residence, atrazine and chlorotriazine concentrations in tap water, municipal water and urine, and estimated dose from water consumption. Women who lived in Illinois were more likely to report menstrual cycle length irregularity (odds ratio (OR)=4.69; 95% confidence interval (CI): 1.58-13.95) and more than 6 weeks between periods (OR=6.16; 95% CI: 1.29-29.38) than those who lived in Vermont. Consumption of >2 cups of unfiltered Illinois water daily was associated with increased risk of irregular periods (OR=5.73; 95% CI: 1.58-20.77). Estimated "dose" of atrazine and chlorotriazine from tap water was inversely related to mean mid-luteal estradiol metabolite. Atrazine "dose" from municipal concentrations was directly related to follicular phase length and inversely related to mean mid-luteal progesterone metabolite levels. We present preliminary evidence that atrazine exposure, at levels below the US EPA MCL, is associated with increased menstrual cycle irregularity, longer follicular phases, and decreased levels of menstrual cycle endocrine biomarkers of infertile ovulatory cycles.

Analyzing digital vector waveforms of 0-3000 Hz magnetic fields for health studies.

To improve the assessment of magnetic field exposures for occupational health studies, the Multiwave System III (MW3) was developed to capture personal exposures to the three-dimensional magnetic field vector B(t) in the 0-3000 Hz band. To process hundreds of full-shift MW3 measurements from epidemiologic studies, new computer programs were developed to calculate the magnetic field's physical properties and its interaction with biological systems through various mechanisms (magnetic induction, radical pair interactions, ion resonance, etc.). For automated calculations in the frequency domain, the software uses new algorithms that remove artifacts in the magnetic field's Fourier transform due to electronic noise and the person's motion through perturbations in the geomagnetic field from steel objects. These algorithms correctly removed the Fourier transform artifacts in 92% of samples and have improved the accuracy of frequency-dependent metrics by as much as 3300%. The output of the MwBatch software is a matrix of 41 exposure metrics calculated for each 2/15 s sample combined with 8 summary metrics for the person's full-period exposure, giving 294 summary-exposure metrics for each person monitored. In addition, the MwVisualizer software graphically explores the magnetic field's vector trace, its component waveforms, and the metrics over time. The output was validated against spreadsheet calculations with pilot data. This software successfully analyzed full-shift MW3 monitoring with 507 electric utility workers, comprising over 1 million vector waveforms. The software's output can be used to test hypotheses about magnetic field biology and disease with biophysical models and also assess compliance with exposure limits.

Trends in Work-Related Musculoskeletal Disorders From the 2002 to 2014 General Social Survey, Quality of Work Life Supplement.

OBJECTIVE: To update trends in prevalence of back and upper limb musculoskeletal symptoms and risk factors from the 2014 Quality of Work Life (QWL) Survey. METHODS: Quadrennial QWL Surveys, 2002 to 2014 (with N = 1455, 1537, 1019, and 1124 in 2002, 2006, 2010, and 2014 surveys respectively) were analyzed for reports of back pain and pain in arms. RESULTS: In the fourth analysis of this survey, 12-year trends continue to show a decline in back pain and pain in arms. Key physical (heavy lifting, hand movements, very hard physical effort) and psychosocial/work organizational factors (low supervisor support, work is always stressful, not enough time to get work done) remain associated with back and arm pain, with the physical risk factors showing the strongest associations. CONCLUSION: Physical exposure risk factors continue to be strongly associated with low back and arm pain and should be the focus of intervention strategies.

Results of the National Institute for Occupational Safety and Health-U.S. Environmental Protection Agency interlaboratory comparison of American National Standards Institute S12.6-1997 Methods A and B.

The National Institute for Occupational Safety and Health and the Environmental Protection Agency sponsored the completion of an interlaboratory study to compare two fitting protocols specified by ANSI S12.6-1997 (R2002) [(2002). American National Standard Methods for the Measuring Real-Ear Attenuation of Hearing Protectors, American National Standards Institute, New York]. Six hearing protection devices (two earmuffs, foam, premolded, custom-molded earplugs, and canal-caps) were tested in six laboratories using the experimenter-supervised, Method A, and (naive) subject-fit, Method B, protocols with 24 subjects per laboratory. Within-subject, between-subject, and between-laboratory standard deviations were determined for individual frequencies and A-weighted attenuations. The differences for the within-subject standard deviations were not statistically significant between Methods A and B. Using between-subject standard deviations from Method A, 3-12 subjects would be required to identify 6-dB differences between attenuation distributions. Whereas using between-subject standard deviations from Method B, 5-19 subjects would be required to identify 6-dB differences in attenuation distributions of a product tested within the same laboratory. However, the between-laboratory standard deviations for Method B were -0.1 to 3.0 dB less than the Method A results. These differences resulted in considerably more subjects being required to identify statistically significant differences between laboratories for Method A (12-132 subjects) than for Method B (9-28 subjects).

The relationships between blood lead levels and serum thyroid stimulating hormone and total thyroxine in the third National Health and Nutrition Examination Survey.

Regression analysis was used to estimate and test for relationships between the blood lead concentration and the concentrations of serum thyroid stimulating hormone and serum total thyroxine in adults, 20 years and older, participating in the third National Health and Nutrition Examination Survey. No relationship was found between the blood lead level and the concentration of serum thyroid stimulating hormone. The serum total thyroxine concentration decreased as the blood lead level increased in women, but not in men. The lowest concentration of blood lead at which a relationship could be detected was 2.1 µg/dL and 3.9 µg/dL for the non-pregnant and pregnant women, respectively. Hypothetical mechanisms of the action of lead are discussed.

Chronic inhalation of short asbestos: lung fiber burdens and histopathology for monkeys maintained for 11.5 years after exposure.

In an earlier report, Platek et al. (1985) presented the results of an 18-month inhalation exposure of rats and monkeys to short chrysotile asbestos. The mean chamber exposure level was 1.0 mg/m(3) with an average of 0.79 fibers/ml > 5 microm in length. Gross and histopathological examination of exposed and control rats indicated no treatment-related lesions. Asbestos bodies adjacent to the terminal bronchioles, but no fibrosis, were found in lung biopsy tissue taken from the exposed monkeys at 10 months post-exposure. Fifteen monkeys (9 exposed and 6 controls) from this study were maintained for 11.5 years following exposure. Lung fiber burdens were determined by transmission electron microscopy. The mean lung burden (+/- standard deviation) for 59 samples from exposed monkeys was 63 +/- 30 x 10(6) fibers/g dry lung (range, 18-139 x 10(6)). The geometric mean fiber length was 3.5 microm with 35% of the fibers being > 5 microm in length. These data indicate some chrysotile fibers are durable in vivo for a significant period of time. Lungs were examined grossly and microscopically. No lesions attributable to the inhalation exposure were noted. Asbestos bodies were seen in the lungs of treated monkeys, primarily in the interstitium near bronchioles or small pulmonary blood vessels (which also may have been near to bronchioles just out of the plane of section).

Evaluation of handle shapes for screwdriving.

This study investigated the effects of screwdriver handle shape, surface, and workpiece orientation on subjective discomfort, number of screw-tightening rotations, screw-insertion time, axial screwdriving force, and finger contact forces in a screwdriving task. Handles with three longitudinal cross-sectional shapes (circular, hexagonal, triangular), four lateral shapes (cylindrical, double frustum, reversed double frustum, cone), and two surface materials (plastic, rubber coated) were tested. Individual phalangeal segment force distributions indicated how fingers and phalangeal segments were involved in the creation of total finger force (15.0%, 34.6%, 34.5%, and 15.9% for the index, middle, ring, and little fingers; and 45.7%, 22.4%, 12.9%, and 19.0% for the distal, middle, proximal, and metacarpal phalanges, respectively). From this finding, the index and little fingers appeared to contribute mainly in the guiding and balancing of the screwdriver handles, whereas middle and ring fingers played a more prominent role in gripping and turning. Participants preferred circular and hexagonal longitudinal-shaped and double frustum and cone lateral-shaped handles over the triangular longitudinal-shaped handles, and cylindrical and reversed double frustum lateral-shaped handles. Circular, cylindrical, and double frustum handles exhibited the least total finger force associated with screw insertion. In terms of combinations of longitudinal and lateral shapes, circular with double frustum handles were associated with less discomfort and total finger force.

A cross-sectional study of risk factors for musculoskeletal symptoms in the workplace using data from the General Social Survey (GSS).

OBJECTIVE: Assessments of potential risk factors for musculoskeletal disorders (MSDs) from large, national study populations using personal interviews are critical to our understanding of exposure-response relationships. To address this need, we analyzed two outcome measures--self-reported back pain and upper extremity pain--from the quality of work life (QWL) module of the General Social Survey (GSS). We investigated several individual, psychosocial, and physical factors for their relationship to these outcome measures. METHODS: The study population included US adults, noninstitutionalized, English-speaking, aged 18 years or older, and employed at least part time (>or=20 hr/wk). Final sample size was 1484 workers. RESULTS: Variables of physical exposure significantly increased the risk of both low back pain and upper extremity pain. Multiple injuries and some psychosocial factors were associated with MSDs, and there was an additive effect on risk of MSDs with exposure to both physical exposure and work stress. CONCLUSIONS: A relationship between physical loads and musculoskeletal disorders was indicated by the results, which will enable creating a database for tracking reports of MSDs in the US working population.

Associations between urinary biomarkers of polycyclic aromatic hydrocarbon exposure and reproductive function during menstrual cycles in women.

Essentially all women are exposed to polycyclic aromatic hydrocarbons (PAHs), formed during incomplete combustion of organic materials, including fossil fuels, wood, foods, and tobacco. PAHs are ovarian toxicants in rodents, and cigarette smoking is associated with reproductive abnormalities in women. Biomonitoring of hydroxylated PAH (OH-PAH) metabolites in urine provides an integrated measure of exposure to PAHs via multiple routes and has been used to characterize exposure to PAHs in humans. We hypothesized that concentrations of OH-PAHs in urine are associated with reproductive function in women. We recruited women 18-44years old, living in Orange County, California to conduct daily measurement of urinary luteinizing hormone (LH) and estrone 3-glucuronide (E13G) using a microelectronic fertility monitor for multiple menstrual cycles; these data were used to calculate endocrine endpoints. Participants also collected urine samples on cycle day 10 for measurement of nine OH-PAHs. Models were constructed for eight endpoints using a Bayesian mixed modeling approach with subject-specific random effects allowing each participant to act as a baseline for her set of measurements. We observed associations between individual OH-PAH concentrations and follicular phase length, follicular phase LH and E13G concentrations, preovulatory LH surge concentrations, and periovulatory E13G slope and concentration. We have demonstrated the feasibility of using urinary reproductive hormone data obtained via fertility monitors to calculate endocrine endpoints for epidemiological studies of ovarian function during multiple menstrual cycles. The results show that environmental exposure to PAHs is associated with changes in endocrine markers of ovarian function in women in a PAH-specific manner.

Menstrual cycle perturbation by organohalogens and elements in the Cree of James Bay, Canada.

Persistent organohalogens (POHs) and metals have been linked to alterations in menstrual cycle function and fertility in humans. The Cree First Nations people living near James Bay in Ontario and Quebec, Canada, have elevated levels of POHs, mercury and lead compared to other Canadians. The present study examines the interrelationships between selected POHs and elements on menstrual cycle function in these Cree women. Menstrual cycle characteristics were derived from structured daily diaries and endocrine measurements from daily urine samples collected during one cycle for 42 women age 19-42. We measured 31 POHs in blood plasma and 18 elements in whole blood, for 31 of the participants. POHs and elements detected in ≥ 70% of the participants were transformed by principal component (PC) analysis to reduce the contaminant exposure data to fewer, uncorrelated PCA variables. Multiple regression analysis revealed that, after adjusting for confounders, PC-3 values showed significant negative association with cycle length, after adjusting for confounders (p = 0.002). PC-3 accounted for 9.2% of the variance and shows positive loadings for cadmium, selenium, and PBDE congeners 47 and 153, and a negative loading for copper. Sensitivity analysis of the model to quantify likely effect sizes showed a range of menstrual cycle length from 25.3 to 28.3 days using the lower and upper 95% confidence limits of mean measured contaminant concentrations to predict cycle length. Our observations support the hypothesis that the menstrual cycle function of these women may be altered by exposure to POHs and elements from their environment.

The relationship between blood lead levels and neurobehavioral test performance in NHANES III and related occupational studies.

OBJECTIVES: The goals of this study were two-fold: (1) to assess the relationship between blood lead levels and neurobehavioral test performance in a nationally sample of adults from the third National Health and Nutrition Evaluation Survey and (2) to analyze the results from previously published studies of occupational lead exposure that used the same neurobehavioral tests as those included in the survey. METHODS: Regression models were used to test and estimate the relationships between measurements of blood lead and performance on a simple reaction time, a symbol-digit substitution, and a serial digit learning test in adults aged 20-59 years who participated the survey. Mixed models were used to analyze the data from the occupational studies. RESULTS: The blood lead levels of those participating in the survey ranged from 0.7 to 41.8 microg/dl. The estimated geometric mean was 2.51 microg/dl, and the estimated arithmetic mean was 3.30 microg/dl. In the survey, no statistically significant relationships were found between blood lead concentration and performance on the three neurobehavioral tests when adjusted for covariates. In the occupational studies, the groups exposed to lead consistently performed worse than control groups on the simple reaction time and digit-symbol substitution tests. CONCLUSIONS: The results from the survey and the occupational studies do not provide evidence for impairment of neurobehavioral test performance at levels below 25 microg/dl, the concentration that the Centers for Disease Control and Prevention define as elevated in adults. The average blood lead level of the exposed groups in the occupational studies was 41.07 microg/dl, less than 50 microg/dl, the minimum concentration that the Occupational Safety and Health Administration requires for medical removal from the workplace. Given the evidence of impaired neurobehavioral performance in these groups, the 50 microg/dl limit should be reevaluated.

Further Trends in Work-Related Musculoskeletal Disorders: A Comparison of Risk Factors for Symptoms Using Quality of Work Life Data From the 2002, 2006, and 2010 General Social Survey.

OBJECTIVE: To report trends for the risk of musculoskeletal disorders. METHODS: Three Quality of Work Life surveys examine the risk factors for musculoskeletal disorders. RESULTS: Findings similar for several risk factors, but differences across the reporting years may reflect economic conditions. Respondent numbers in 2010 were reduced, some risk factors had pattern changes, and there were sex and age differences. Trend analysis showed most significant changes were for the "work fast" risk factor. New 2010 "physical effort" item showed sex differences, and items reflective of total worker health showed strong associations with "back pain" and "pain in arms." CONCLUSIONS: Intervention strategies should focus on physical exposures and psychosocial risk factors (work stress, safety climate, job satisfaction, supervisor support, work fast, work freedom, work time) that have been consistently related to reports of musculoskeletal disorders. Economic conditions will influence some psychosocial risk factors.