Asbestos-containing materials in abandoned residential dwellings in Detroit.

OBJECTIVE: The efforts of many municipalities to demolish abandoned residential dwellings (ARDs) are hampered by the presence of asbestos-containing materials (ACMs) in these structures. However, the extent of such materials is unknown. Our study sought to characterize ACMs present in ARDs demolished in Detroit. METHODS: Working with the City of Detroit, we obtained information on all ARDs demolished from 2014 to 2017. We randomly sampled 605 ARDs and analyzed the presence, type, and amount of ACM present, and the associated abatement and demolition costs. RESULTS: Asbestos was present in about 95% of the sampled ARDs. The most common types of ACMs were flooring, roofing, siding, and duct insulation. The material containing the greatest fraction of asbestos was duct insulation. The type of asbestos generally present was chrysotile. Only eight (1%) ARDs contained commercial amphibole asbestos; another 36 contained vermiculite. The total cost of demolition averaged $13,645 per home, of which 20.1% was asbestos abatement. CONCLUSIONS: The majority of the ACM in the ARDs was nonfriable and consisted of chrysotile. This study contributes information about the nature and extent of ACM in ARDs, which can provide part of the foundation for making an assessment of possible asbestos-containing air emissions during the demolitions of ARDs, and the nature or extent of pre-demolition abatement that may be needed (if any) to protect the public's health.

Digital radiological surveillance of silicosis and related tuberculosis in the South African mining industry practical and technical considerations

The switch from analogue to digital radiography formats for surveillance for silicosis and tuberculosis in the South African mining industry raised the question of equivalence of formats for this purpose. As a result, the South African Mine Health and Safety Council (MHSC) sponsored a study, recently published, on the equivalence of digital and analogue radiography in this setting. This commentary aims to provide a summary of the study findings, accompanied by an overview of the practical considerations that arise in the use of digital radiographic surveillance in the South African mining industry. Through a clear understanding of the objectives of surveillance, use of quality and reference standards for hardware and software, and interpretation of digital images, avoidance of common pitfalls, and use of all the clinical and occupational health information on each miner, the contribution of surveillance to identification and control of silicosis and tuberculosis in the mining industry can be maximised

Human exposure from dioxins in soil.

Dioxins are a family of chemical compounds that has received considerable attention, both historically and currently. This article reviews scientific field studies that examine the relationship between living on soil contaminated with dioxins and the level of dioxins in people's serum, with an emphasis on the University of Michigan Dioxin Exposure Study (UMDES), the largest and most comprehensive study of its kind. These studies conclude that the levels of dioxins in serum are most strongly correlated with age, gender, body mass index, weight loss, breast feeding, and smoking. Levels of dioxins in soil are not significant predictors for dioxin concentrations in serum. The increase in serum dioxin levels that is seen with age results from historic exposure and does not represent ongoing exposure. Based on the scientific field studies conducted to date, it appears that, in the absence of the consumption of contaminated animal products, there is little evidence of ongoing exposure from contaminated soil.

Diagnostic strategies using physical examination are minimally useful in defining carpal tunnel syndrome in population-based research studies.

OBJECTIVE: We evaluated the utility of physical examination manoeuvres in the prediction of carpal tunnel syndrome (CTS) in a population-based research study. METHODS: We studied a cohort of 1108 newly employed workers in several industries. Each worker completed a symptom questionnaire, a structured physical examination and nerve conduction study. For each hand, our CTS case definition required both median nerve conduction abnormality and symptoms classified as "classic" or "probable" on a hand diagram. We calculated the positive predictive values and likelihood ratios for physical examination manoeuvres in subjects with and without symptoms. RESULTS: The prevalence of CTS in our cohort was 1.2% for the right hand and 1.0% for the left hand. The likelihood ratios of a positive test for physical provocative tests ranged from 2.0 to 3.3, and those of a negative test from 0.3 to 0.9. The post-test probability of positive testing was <50% for all strategies tested. CONCLUSION: Our study found that physical examination, alone or in combination with symptoms, was not predictive of CTS in a working population. We suggest using specific symptoms as a first-level screening tool, and nerve conduction study as a confirmatory test, as a case definition strategy in research settings.

Statistical comparison of residential soil concentrations of PCDDs, PCDFs, and PCBs from two communities in Michigan.

The University of Michigan dioxin exposure study was undertaken to address concerns that the industrial discharge of dioxin-like compounds in the Midland, MI area had resulted in contamination of soils in the Tittabawassee River floodplain and downwind of the incinerator. The study was designed in a rigorously statistical manner comprising soil measurements of 29 polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) from 766 residential properties, selected probabilistically, in the Midland area and in Jackson and Calhoun Counties (Michigan) as a background comparison. A statistical comparison determined that the geometric mean toxic equivalent (TEQ) levels in samples from the target populations were statistically significantly above background. In addition, the probabilities of being above the 75th and 95th percentiles of background were also greater. Congener contributions to the TEQ were dominated by 2,3,4,7,8-PeCDF and 2,3,7,8-TCDF in the floodplain and by 2,3,7,8-TCDD in the incinerator plume. However, PCB 126 was the top congener contributing to the background TEQ. On the basis of statistical inference to the total population, it was estimated that about 36% of the properties in the floodplain and incinerator plume have at least one soil sample over the Michigan Department of Environmental Quality's soil direct contact criterion of 90 pg/g TEQ.

Prolonged median sensory latency as a predictor of future carpal tunnel syndrome.

The purpose of the study was to determine whether abnormal median sensory nerve conduction among asymptomatic workers was predictive of future symptoms suggestive of carpal tunnel syndrome (CTS). This was a prospective study involving 77 workers who were identified as asymptomatic cases with electrodiagnostic findings of median mononeuropathy compared to an age- and sex-matched control group. Follow-up was completed an average of 70 months later, and subjects who reported pain, numbness, tingling, or burning in the distribution of the median nerve, based upon a hand diagram, were classified as having CTS symptoms. The follow-up participation rate was 70%. Among subjects with abnormal median sensory latencies, 23% went on to develop symptoms consistent with CTS within the follow-up period, compared with 6% in the control group (P= .010). Age and hand repetition were also risk factors for CTS, but the majority of asymptomatic workers with a median mononeuropathy do not become symptomatic over an extended time.

Prevalence of carpal tunnel syndrome and median mononeuropathy among dentists.

BACKGROUND: The authors undertook a study to determine the prevalence in dentists of abnormal sensory nerve conduction and/or symptoms of carpal tunnel syndrome, or CTS, the most common nerve entrapment syndrome. METHODS: In a cross-sectional study, dentists (n = 1,079) were screened during the American Dental Association's Annual Health Screening Program in 1997 and 1998 by means of standard electrodiagnostic measures in the dominant hand and a self-reported symptom questionnaire. The authors diagnosed a median mononeuropathy from a 0.5- or 0.8-millisecond, or ms, prolongation of the median sensory-evoked peak latency compared to the ulnar latency. They diagnosed CTS if the subject also had accompanying symptoms of numbness, tingling or pain. RESULTS: Thirteen percent of screened dentists were diagnosed with a median mononeuropathy (using a 0.5-ms prolongation as the criterion), but only 32 percent of these had symptoms consistent with CTS (4.8 percent overall). When the 0.8-ms prolongation was used as the electrodiagnostic criterion, only 2.9 percent (overall) were diagnosed with CTS. People with diabetes, rheumatoid arthritis and obesity were more likely to have a median mononeuropathy. CONCLUSIONS: The prevalence of symptoms consistent with CTS in the dominant hand among dentists was higher than the prevalence in the general population. However, when electrodiagnostic confirmation is added, the prevalence of CTS was nearly the same as that among the general population. CLINICAL IMPLICATIONS: Early recognition of CTS can lead to more effective management. Education regarding ergonomic risk factors can be an effective preventive measure.

Developing ergonomic solutions for prevention of musculoskeletal disorder disability.

Numerous models have been proposed to help understand the relationship between personal and work factors that affect participation in work. The authors use a generic version of these models as a framework for identifying gaps between job demands and worker capacities. They describe metrics for assessing factors associated with causing or aggravating musculoskeletal disorders. Two case examples are presented to illustrate the hierarchical assessment of jobs and the evaluation of gaps between job demands and worker capacities. Finally, the authors describe the development of a job database to facilitate future evaluations.

Test-retest reliability of the Upper Extremity Questionnaire among keyboard operators.

BACKGROUND: Questionnaires are often used in research among workers although few have been tested in the working population. The Upper Extremity Questionnaire is a self-administered questionnaire designed for epidemiological studies and tested among workers. This study assessed reliability of the instrument. METHODS: A two-part assessment was conducted among 138 keyboard operators as part of a large medical survey. Test-retest reliability was analyzed using the kappa statistic, paired t-test, and intraclass correlation coefficient (ICC). Logistic regression models were used to test the effect of demographic and work-related factors on reliability. RESULTS: The average respondent was a white woman, age 35 years, with some college education, in permanent employment with tenure of 1.4 years. Overall, reports of symptoms were stable from Round 1 to 2. Most kappa values for symptom reports were between 0.60 and 0.89. Kappa values for right and left hand diagrams were 0.57 and 0.28, respectively. Among psychosocial items, Perceived Stress and Job Dissatisfaction Scales were most reliable (ICC = 0.88); co-worker support was least reliable (ICC = 0.44). CONCLUSION: Reliability of items on the Upper Extremity Questionnaire were generally good to excellent. Reports of symptom severity and interference with work were less stable. Demographic and work-related factors were not statistically significant in modeling the variation in reliability. Repeated use of the questionnaire with similar results suggests findings are applicable to a larger working population.

Classification criteria and severity assessment in work-associated upper extremity disorders: methods matter.

Work-associated musculoskeletal disorders of the upper extremity are common and disabling. Research on these disorders is needed and requires valid methods of classification of the disorders for epidemiologic studies and measurement of their impact on functional status. This commentary discusses the methodologic aspects of classification and functional status assessment in upper extremity musculoskeletal disorders.

Characterization of metalworking fluid exposure indices for a study of acute respiratory effects.

Although metalworking fluids have been widely used throughout industry for decades, occupational exposures to metalworking fluid aerosols and their constituents have not been well characterized. This article describes an exposure assessment for a study of metalworking fluid aerosols and acute respiratory effects. This exposure assessment was unique in its inclusion of multiple exposure measures relevant to a complex environment, and extensive personal sampling for bacteria and endotoxin. The specific objectives were to: (1) obtain indices of personal exposure to metalworking fluid aerosols in an automotive transmission plant, either directly (by sampling) or indirectly (by estimation), and (2) identify and adjust for sources of error in exposure/dose measures, where possible. No prior studies have characterized personal exposures to metalworking fluid aerosols so extensively. Exposure data were obtained during a pilot phase and three principal rounds of data collection over a 15-month period in conjunction with spirometric testing. Subjects worked in one of two machining departments, Case and Valve Body, or in a comparison department, Final Assembly. The primary exposure measures for this study were thoracic fraction particulate, thoracic fraction bacteria (viable plus non-viable), and total endotoxin. Mean personal air concentrations of thoracic particulate across all study rounds were 0.13 mg/m3 in Final Assembly, 0.32 mg/m3 in Valve Body, and 0.56 mg/m3 in Case. Average personal exposures to thoracic fraction bacteria were 0.38 bacteria/cc in Final Assembly, 0.87 bacteria/cc in Valve Body, and 2.66 bacteria/cc in Case. Average personal endotoxin measurements, collected in Round 3 of the study, were 16.4 endotoxin units (EU)/m3 in Assembly, 34.7 EU/m3 in Valve Body, and 234 EU/m3 in Case. Sump fluid contained on the order of 10(8) bacteria/ml, and 10(4)-10(5) EU/ml. Air concentrations of thoracic particulate, thoracic bacteria, and total endotoxin were highly correlated in metalworking operations. Thus, reducing airborne particulate levels should also reduce ambient bacteria and endotoxin, which are suspect agents of respiratory impairment. The elevated endotoxin levels in Final Assembly were unexpected, and suggest an independent source of endotoxin contamination in this department.

Reliability of physical examination of the upper extremity among keyboard operators.

BACKGROUND: Physical examination is a traditional outcome measure in epidemiological research. Its value as a reliable measure depends, in part, on the prevalence of positive findings. The purpose of this paper is to determine the empirical reliability of physical examination and anthropometry in a field study of upper extremity disorders among keyboard operators. METHODS: Two experienced examiners independently performed common provocative tests and procedures in physical examinations of the neck and upper extremity among 160 keyboard operators. Two additional examiners conducted anthropometric surveys among 137 workers. Inter-examiner reliability was assessed with observed agreement, kappa statistics, and intra-class correlations (ICC). RESULTS: Observed agreement was between 96% and 100% for neck and upper extremity signs, muscle stretch reflexes, and muscle strength, however, with the exception of provocative tests, reliability statistics were unstable. Among the provocative tests, Phalen and Tinel tests had modest agreement after adjusting for chance (kappa range: 0.20-0.43). The carpal compression test had the best reliability (kappa=0.60 and kappa=0.67, left and right side, respectively). The ICCs for anthropometry ranged from 0.36-0.91. CONCLUSIONS: Results from the study showed that statistically, except for the carpal compression test, physical examination contributed minimal reliable information. This was attributed mainly to the low prevalence of positive findings, and generally mild nature of upper extremity disorders in this population. The results are the best estimate of what would be found in a field study with experienced examiners. While it may reduce bias, separating physical examination from medical history may contribute to the poor reliability of findings. With a shift toward reliable measures, resources can be allocated to more effective tools, like questionnaires, in epidemiological research of upper extremity disorders among keyboard operators.

Is silicosis required for silica-associated lung cancer?

BACKGROUND: Abundant epidemiologic and experimental evidence supports the 1997 International Agency for Research on Cancer classification of crystalline silica as a human lung carcinogen. Nonetheless, there remains uncertainty about whether excessive lung cancer occurs exclusively among workers with silicosis. METHODS: A review was performed of published occupational epidemiologic literature directly pertinent to the interrelations among silica exposure, silicosis, and lung cancer. RESULTS: The association between silica and lung cancer is generally, but not uniformly, stronger among silicotics than nonsilicotics. However, the existing literature is ambiguous due to incomplete or biased ascertainment of silicosis, inadequate exposure assessment, and the inherently strong correlation between silica exposure and silicosis which hinders efforts to disentangle unique contributions to lung cancer risk. CONCLUSIONS: Until more conclusive epidemiologic findings become available, population-based or individually-based risk assessments should treat silicosis and lung cancer as distinct entities whose cause/effect relations are not necessarily linked.

Reliability of nerve conduction studies among active workers.

Nerve conduction studies play an important role in clinical practice and research. Given their widespread use, reliability of tests merits careful attention. We assessed interexaminer and intraexaminer reliability of median and ulnar sensory nerve measures of amplitude, onset latency, and peak latency. In a two-phase cross-sectional study, two examiners tested 158 workers. Reliability was assessed with intraclass correlations (ICC) and kappa statistics. Median nerve measures were more reliable (ICC range, 0.76 to 0.92) than ulnar measures (ICC range, 0.22 to 0.85). Ulnar-onset latencies had the worst reliability. The median-ulnar peak latency difference was a particularly stable measure (ICC range, 0.79 to 0.92). The median-ulnar peak latency difference had high interexaminer reliability (kappa range, 0.71 to 0.79) for normal tests defined by cut points of 0.8 ms and 0.5 ms. Intraexaminer reliability was higher with the 0.8-ms cut point (kappa = 0.90 and kappa = 0.85 for examiners 1 and 2, respectively). Rather than absolute cut points to describe normality, a more rational interpretation of results can be made with ordered categories or continuous measures.

Cross-sectional study of the relationship between repetitive work and the prevalence of upper limb musculoskeletal disorders.

BACKGROUND: This study examined the relationship of repetitive work and other physical stressors to prevalence of upper limb discomfort, tendinitis, and carpal tunnel syndrome. METHODS: Three hundred fifty-two workers from three companies participated. Job exposure levels for repetition and other physical stressors were quantified using an observational rating technique. Ergonomic exposures were rated on a 10-point scale, where 0 corresponded to no stress and 10 corresponded to maximum stress. Job selection was based on repetition (three categories: high, medium, and low) to ensure a wide range of exposures. Physical evaluations on all participating workers were performed by medical professionals and included a self-administered questionnaire, physical exam, and limited electrodiagnostic testing. RESULTS: Repetitiveness of work was found to be significantly associated with prevalence of reported discomfort in the wrist, hand, or fingers (odds ratio (OR) = 1.17 per unit of repetition; OR = 2.45 for high vs. low repetition), tendinitis in the distal upper extremity (OR = 1.23 per unit of repetition; OR = 3.23 for high vs. low repetition), and symptoms consistent with carpal tunnel syndrome (OR = 1.16 per unit of repetition; OR = 2.32 for high vs. low repetition). An association was also found between repetitiveness of work and carpal tunnel syndrome, indicated by the combination of positive electrodiagnostic results and symptoms consistent with carpal tunnel syndrome (OR = 1. 22 per unit of repetition; OR = 3.11 for high vs. low repetition). CONCLUSIONS: These findings indicate that repetitive work is related to upper limb discomfort, tendinitis, and carpal tunnel syndrome in workers. Further research with a wider range of exposures is needed to evaluate the effects of other physical stresses alone and in combination.

Absence of polyneuropathy among workers previously diagnosed with solvent-induced toxic encephalopathy.

An association between polyneuropathy and occupational exposure to trichloroethylene, trichloroethane, perchloroethylene, or similar solvents alone or in combination is controversial. We sought to determine whether workers previously diagnosed with solvent-induced toxic encephalopathy had objective evidence of polyneuropathy. Thirty railroad workers previously diagnosed with toxic encephalopathy were examined in the context of litigation against their employers. All described long-term occupational solvent exposure averaging 20 years in duration (range, 10 to 29 years) and producing acute intoxication on a regular basis. The diagnosis of subclinical or clinical polyneuropathy was established using a combination of symptoms, signs, and nerve conduction study (NCS) measures, consistent with standard clinical practice. Potential confounders were identified. NCS results were compared with historical controls, including unexposed workers matched by gender, age, and body mass index. Dose-response relationships were evaluated using simple linear and stepwise regression models. Three workers fulfilled clinical polyneuropathy criteria. The only worker fulfilling NCS criteria for confirmed clinical polyneuropathy had diabetes mellitus. Mean NCS values for most measures were similar to control values, and existing differences in sensory amplitudes disappeared when compared with the matched control group. NCS measures were not significantly influenced by exposure duration or job title. Separation into groups on the basis of the presence or absence of polyneuropathy symptoms, previous diagnosis of polyneuropathy, disability status, and severity or type of encephalopathy did not demonstrate significant NCS differences. The complaints of these workers claiming neurotoxic injury from occupational solvent exposure are not explained by peripheral nervous system dysfunction.

Agreement between symptom surveys, physical examination procedures and electrodiagnostic findings for the carpal tunnel syndrome.

OBJECTIVES: The goal of this study was to evaluate the concordance between various clinical screening procedures for carpal tunnel syndrome. METHODS: The subject population consisted of 824 workers from 6 facilities. The evaluated procedures included bilateral sensory nerve conduction testing, physical examinations, and symptom surveys, including hand diagrams. The agreement between the outcomes of various combinations of these procedures was assessed by determining the kappa coefficient. RESULTS: There was relatively poor overlap between the reported symptoms, the physical examination findings, and the electrodiagnostic results consistent with carpal tunnel syndrome. Overall, only 23 out of 449 subjects (5%) with at least 1 positive finding met all 3 criteria (symptoms, physical examination findings, and electrophysiological results consistent with carpal tunnel syndrome) for the dominant hand. The screening procedures showed poor or no agreement with kappa values ranging between 0.00 and 0.18 for all the case definitions evaluated for carpal tunnel syndrome. CONCLUSIONS: The poor overlap between the various screening procedures warns against the use of electrodiagnostic findings alone without the symptom presentation being considered. The results of this study also point to a need for the further development and evaluation of methods for detecting carpal tunnel syndrome.

Perceived psychological stress and upper extremity cumulative trauma disorders.

This report presents data exploring the relationship between perceived psychological stress and several variables implicated in the etiology of upper extremity cumulative trauma disorders (UECTDs). The sample was 354 workers from three different manufacturing companies. The primary job exposure for the subjects was that they were engaged in jobs that involved repetitious movements of the upper extremities, primarily of the hands and arms. Data collection included a detailed health history, a comprehensive physical examination of the upper extremities, limited electrodiagnostic testing, Cohen's Perceived Stress Scale, Karasek's Job Content Questionnaire, demographic information, and a measurement of repetition. Descriptive analyses, analysis of variance, correlational analyses, and multiple linear regression were used to examine the data. Perceived stress, as measured in this study, was only weakly associated with repetition, job dissatisfaction, and subjective complaints related to UECTDs. In addition, factors generally accepted as related to UECTDs (e.g., repetition, female gender, hormonal influences, and existing medical conditions) were not robust predictors of perceived stress. The major limitation is related to the measurement of perceived psychological stress. Like most psychosocial phenomena, perceived stress is a complex construct, one that is difficult to measure and correlate with health outcomes. Further research is necessary to examine what role, if any, perceived stress may have in the etiology of UECTDs.