N-acetyltransferase 1 polymorphism increases cotinine levels in Caucasian children exposed to secondhand smoke: the CCAAPS birth cohort.

Cotinine is a proxy for secondhand smoke (SHS) exposure. Genetic variation along nicotine and cotinine metabolic pathways may alter the internal cotinine dose, leading to misinterpretations of exposure-health outcome associations. Caucasian children with available SHS exposure and hair cotinine data were genotyped for metabolism-related genes. SHS-exposed children had 2.4-fold higher hair cotinine (0.14±0.22 ng mg(-1)) than unexposed children (0.06±0.05 ng mg(-1), P<0.001). SHS-exposed children carrying the NAT1 minor allele had twofold higher hair cotinine (0.18 ng mg(-1) for heterozygotes and 0.17 ng mg(-1) for homozygotes) compared with major allele homozygotes (0.09 ng mg(-1), P=0.0009), even after adjustment for SHS dose. These findings support that NAT1 has a role in the metabolic pathway of nicotine/cotinine and/or their metabolites. The increased cotinine levels observed for those carrying the minor allele may lead to SHS exposure misclassification in studies utilizing cotinine as a biomarker. Additional studies are required to identify functional single-nucleotide polymorphism(s) (SNP(s)) in NAT1 and elucidate the biological consequences of the mutation(s).

Duration of day care attendance during infancy predicts asthma at the age of seven: the Cincinnati Childhood Allergy and Air Pollution Study.

BACKGROUND: Studies vary with respect to the reported effects of day care attendance on childhood asthma. OBJECTIVES: To evaluate the independent and combined effects of day care attendance and respiratory infections on the development of asthma at the age of seven in a prospective birth cohort. METHOD: At the age of seven, the study sample included 589 children with complete data of 762 enrolled at birth. Day care hours and number of respiratory infections were reported in follow-up questionnaires through age four. At 7 years of age, asthma was diagnosed in 95 children (16%), based on predefined symptoms criteria confirmed by either asthma FEV1 reversibility after bronchodilator or a positive methacholine test (PC20 ≤ 4 mg/mL). Logistic regression was used to investigate the relationships between asthma at the age of seven, cumulative hours of day care attendance and reported respiratory infections at ages 1-4. RESULTS: In the univariate analyses, day care attendance at 12 months was associated with an increased risk of asthma [odds ratio (OR) = 1.8, 95% confidence interval (CI) = 1.1-3.0]. Both upper and lower respiratory infections at 12 months also increased the likelihood of asthma [OR = 2.4 (1.4-4.1); OR = 2.3 (1.5-3.7), respectively]. In the final multivariate logistic model, cumulative hours of day care attendance and number of lower respiratory infections at 12 months were associated with asthma [OR = 1.2 (1.1-1.5); OR = 1.4 (1.2-1.7), respectively]. However, a threshold of greater than 37.5 hours per week of day care attendance was associated with a lower risk of asthma [OR = 0.6 (0.4-0.9)]. CONCLUSION: Depending on duration of attendance, day care during infancy can either increase or reduce risk of asthma at the age of seven.

Streptomycetes in house dust: associations with housing characteristics and endotoxin.

In addition to mold, indoor bioaerosols also contain bacterial components that may have implications for human health. Endotoxin is a cell wall component in Gram-negative bacteria present at varying levels indoors that has been found to have respiratory health implications. Streptomyces is a large genus of Gram-positive bacteria, and some species have been shown to produce inflammatory reactions in vitro and in vivo. The aim of this study was to determine predictors of streptomycetes levels in house dust and to compare the variation in streptomycetes levels with that in endotoxin levels. Dust was collected by floor vacuuming from 178 homes in the Cincinnati metropolitan area. Streptomycetes levels were measured by quantitative PCR, and endotoxin was assayed by the Limulus amebocyte lysate method. Associations between home characteristics and bacterial contaminants, expressed as concentration and load, were investigated through multiple regression analyses. The presence of two or more dogs was a strong predictor of both streptomycetes and endotoxin levels. Season of dust collection and levels of outdoor molds were predictors of streptomycetes but not endotoxin levels. In contrast, number of inhabitants was a significant predictor of endotoxin load only. Neither streptomycetes nor endotoxin levels were associated with metrics of moisture damage.

Airway obstruction related to diacetyl exposure at microwave popcorn production facilities.

Obstructive lung diseases including bronchiolitis obliterans have been reported among microwave popcorn production employees. Butter flavourings including diacetyl have been associated with these findings. The present study was initiated at four microwave popcorn production plants to determine if exposure to diacetyl was associated with decrements in pulmonary function. Comprehensive diacetyl exposure assessment was undertaken for all job tasks. Spirometry was conducted for 765 full-time employees between 2005 and 2006. Outcomes included decrement in forced expiratory volume in one second (FEV(1)) % predicted, airway obstruction and persistent decline in FEV(1). Inclusion in the high-exposure group (mixers) prior to respirator use was associated with a significantly decreased FEV(1) % pred in non-Asian and Asian males at -6.1 and -11.8% pred, respectively, and an eight-fold increased risk for airway obstruction. Cumulative diacetyl exposure >or=0.8 ppm-yr caused similar results. No significant impact was seen in nonmixers or between current diacetyl exposure and persistent decline in FEV(1). Unprotected exposure as a mixer to butter flavouring including diacetyl resulted in decrements in FEV(1) (% pred) and increased airway obstruction. Control of employee exposure to butter flavouring additives is warranted in regard to both short-term peak and 8-h workday exposure.

House dust (1-3)-beta-D-glucan and wheezing in infants.

BACKGROUND: (1-3)-Beta-D-glucan is a fungal cell wall component, suspected to cause respiratory symptoms in adults. However, very little is known on the possible health effects of (1-3)-beta-D-glucan during infancy. We examined the association between (1-3)-beta-D-glucan exposure and the prevalence of allergen sensitization and wheezing during the first year of life in a birth cohort of 574 infants born to atopic parents. Endotoxin exposure was included as a possible confounder. METHODS: (1-3)-Beta-D-glucan and endotoxin exposures were measured in settled dust collected from infants' primary activity rooms. The primary outcomes at approximately age one included parental reports of recurrent wheezing and allergen sensitization evaluated by skin prick testing to a panel of 15 aeroallergens as well as milk and egg white. RESULTS: Exposure to high (1-3)-beta-D-glucan concentration (within fourth quartile) was associated with reduced likelihood of both recurrent wheezing [adjusted OR (aOR) = 0.39, 95% CI = 0.16-0.93] and recurrent wheezing combined with allergen sensitization (aOR = 0.13, 95% CI = 0.03-0.61). Similar trends were found between (1-3)-beta-D-glucan concentrations and allergen sensitization (aOR = 0.57, 95% CI = 0.30-1.10). In contrast, recurrent wheezing with or without allergen sensitization was positively associated with low (1-3)-beta-D-glucan exposure within the first quartile (aOR = 3.04, 95% CI = 1.25-7.38; aOR = 4.89, 95% CI = 1.02-23.57). There were no significant associations between endotoxin exposure and the studied health outcomes. CONCLUSIONS: This is the first study to report that indoor exposure to high levels of (1-3)-beta-D-glucan (concentration >60 microg/g) is associated with decreased risk for recurrent wheezing among infants born to atopic parents. This effect was more pronounced in the subgroup of allergen-sensitized infants.

An epidemiological appraisal instrument - a tool for evaluation of epidemiological studies.

In recent years, ergonomics practices have increasingly relied upon the knowledge derived from epidemiological studies. In this regard, there is limited research devoted to the exclusive evaluation of the methodological qualities of ergonomics epidemiological studies. The aim of this study was to develop and test a general purpose 'epidemiological appraisal instrument' (EAI) for evaluating the methodological quality of existing or new ergonomic epidemiological studies using a critical appraisal system rooted in epidemiological principles. A pilot EAI version was developed and tested by a team of epidemiologists/physicians/biostatisticians, with the team leader being both epidemiologist and ergonomist. The pilot version was further tested with regard to other raters with/without a background in epidemiology, biostatistics and ergonomics. A revised version was evaluated for criterion validity and reliability. An assessor with a basic background in epidemiology and biostatistics would be able to correctly respond on four out of five questions, provided that subject matter expertise is obtained on specific items. This may improve with the article's quality. Training may have an effect upon assessors with virtually no background in epidemiology/biostatistics, but with a background in ergonomics. In this latter case, the inter-rater degree of agreement is largely above 90% and assessors can resolve their differences in a subsequent round. The EAI proved to be a valid and reliable appraisal instrument that may be used in various applications, such as systematic reviews and meta-analyses.

Pregnancy outcome and progression of diabetic nephropathy. What's next?

OBJECTIVES: The first objective was to assess the association of renal function with maternal and fetal pregnancy outcome in women with diabetic nephropathy. The second objective was to examine the feasibility of a multicenter surveillance program to determine the rates of maternal and fetal pregnancy complications in women with diabetic nephropathy, and to study the effect of pregnancy on the natural history of diabetic renal disease. METHODS: In order to address the first objective, we analyzed data from women with type 1 diabetes and nephropathy enrolled in the Diabetes in Pregnancy Program at our institution. Women were assigned to one of three groups according to enrolment serum creatinine concentration: < or = 1.0 mg/dl, > 1.0 to 1.5 mg/dl and > 1.5 mg/dl. A pilot surveillance program at six centers included women experiencing pregnancy complicated by diabetic nephropathy. In both studies, medical and obstetric history, and maternal and neonatal outcomes, were recorded. Statistical analysis included chi2, logistic regression and analysis of variance. RESULTS: There were 72 pregnancies in 58 women with diabetic nephropathy who enrolled in the pregnancy program. High serum creatinine concentration at enrolment was associated with delivery before 32 weeks' gestation, very low birth weight and increased incidence of neonatal hypoglycemia, independent of quantity of total urinary protein excretion and glycemic control in any trimester. To date, pilot surveillance data have been obtained from six centers on 16 women. Serum creatinine concentrations ranged from 0.4 to 1.1 mg/dl and creatinine clearance from 32 to 317 m/min. Gestational age at delivery ranged from 22 to 39 weeks. CONCLUSIONS: High serum creatinine concentration at enrolment is a risk factor for adverse maternal and neonatal outcome, independent of quantity of total urinary protein excretion and glycemic control during any trimester. A multicenter surveillance program is needed, in order to study less frequent maternal and neonatal outcomes as well as the long-term effects of pregnancy on the natural course of diabetic renal disease.

Electron microscopy study of refractory ceramic fibers.

In epidemiological studies designed to identify potential health risks of exposures to synthetic vitreous fibers, the characterization of airborne fiber dimensions may be essential for assessing mechanisms of fiber toxicity. Toward this end, air sampling was conducted as part of an industry-wide study of workers potentially exposed to airborne fibrous dusts during the manufacture of refractory ceramic fibers (RCF) and RCF products. Analyses of a subset of samples obtained on the sample filter as well as on the conductive sampling cowl were performed using both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to characterize dimensions of airborne fibers. Comparison was made of bivariate fiber size distributions (length and diameter) from air samples analyzed by SEM and by TEM techniques. Results of the analyses indicate that RCF size distributions include fibers small enough in diameter (< 0.25 microm) to be unresolved by SEM. However, longer fibers (> 60 microm) may go undetected by TEM, as evidenced by the proportion of fibers in this category for TEM and SEM analyses (1% and 5%, respectively). Limitations of the microscopic techniques and differences in fiber-sizing rules for each method are believed to have contributed to the variation among fiber-sizing results. It was concluded from these data that further attempts to characterize RCF exposure in manufacturing and related operations should include analysis by TEM and SEM, since the smallest diameter fibers are not resolved with SEM and the fibers of longer length are not sized by TEM.

Reliability and validity of chest radiograph surveillance programs.

STUDY OBJECTIVES: Due to the lack of consensus in the literature in the use of posteroanterior (PA) vs PA with right and left oblique views as the optimum radiograph surveillance methodology to investigate pleural changes, a study was undertaken to evaluate the reliability, sensitivity, and specificity of these two approaches. DESIGN: Three experienced radiologist B readers used the 1980 International Labor Office classification system for pneumoconiosis to independently read chest radiographs of workers with individual identifiers masked. All radiographs were read first as a PA view only. Unknown to the B readers, each subject's PA was then matched to his or her corresponding right and left oblique views (film triad) and re-read several weeks later. SETTING AND PARTICIPANTS: The respiratory health of 652 workers exposed to refractory ceramic fiber was assessed as part of cross-sectional and longitudinal surveillance programs. MEASUREMENTS AND RESULTS: kappa Statistics for interreader and intrareader reliability between the PA view and film triad methods were calculated. Sensitivity, specificity, and positive predictive value were assessed by comparing the initial cross-sectional study to the longitudinal study. The film triad method had considerably higher interreader reliability (kappa = 0.59) compared to the PA-only method (kappa = 0.44). Results from the initial cross-sectional study were then compared to findings evaluated longitudinally. The film triad again was superior, demonstrating a positive predictive value of 73.7% compared to only 47.8% for the PA method. CONCLUSIONS: It is our recommendation that the film triad method be used in surveillance studies where both parenchymal and pleural changes are anticipated.

Exertion and body discomfort perceived symptoms associated with carpentry tasks: an on-site evaluation.

The purpose of this study was to determine how carpenters subjectively perceived the exertion level and body discomfort associated with their daily tasks. Two psychophysical instruments were utilized. The Borg Whole Body Physical Exertion Instrument, a measure of overall physical demand, and the Body Segment instrument (modified Bishop-Corlett Scale), a measure of body discomfort, were given to 73 carpenters at the end of a shift. Carpentry specialties evaluated included ceiling, drywall, formwork, finishing work, pile driving, fixtures, welding, and scaffolding. The mean Borg's exertion score for the subjects combining all specialties was 14.4 (+/-2.51 standard deviation), a score between "somewhat hard" and "hard." The perception of whole body physical exertion appeared to be a consequence of the specific task. There was no significant correlation between whole body physical exertion perception and age or the number of years as a carpenter. The findings from the body discomfort scale for the total group indicated that the three primary discomfort frequencies by body segment were mid-to-lower back (65.8%), knees (45.2%), and the neck (28.8%). The next highest discomfort rating by body segment (back, knee, right wrist, right leg/foot, and right shoulder) for those subjects in the top three job specialties represented (drywall, ceiling, and formwork; n = 38) resulted in significantly higher ratings for back (60.5%) than right leg/foot (34.2%) and right shoulder (31.6%). All other body segment ratings were not significantly different from one another using Tukey's studentized range test.

Menstrual disorders and occupational, stress, and racial factors among military personnel.

Few studies have assessed multiple stress factors as a potential risk for menstrual disorders. This study evaluated whether work-related stress or life event stress was associated with alterations in menstrual function of military personnel. The study is unique in that it evaluated the association between race and three job factors--job stress, handling chemical mixtures, and being a military or civilian employee of the US Air Force. A comprehensive questionnaire was administered to 170 healthy, premenopausal employed women to examine the relationship between work-related or life event stress and menstrual disorders. Multiple logistic regression analyses showed no statistically significant association between work-related stress and menstrual disorders, whereas life event stress was significantly associated with dysmenorrhea (odds ratio [OR], 2.20; 95% confidence interval [CI], 1.08 to 4.50) abnormal cycle length (OR, 3.42; CI, 1.12 to 10.50), and hypermenorrhea (OR, 2.99; 95% CI, 1.20 to 7.42). Having one or more menstrual disorders was significantly associated with life events by race interaction (OR, 6.52; 95% CI, 2.45 to 17.36). Non-Caucasians had significantly increased risks of hypermenorrhea (OR, 4.99; 95% CI, 2.07 to 12.05) and abnormal cycle length (OR, 4.12; 95% CI, 1.47 to 11.55). The prevalence of menstrual disorders in this military population was 31.2% for dysmenorrhea, 17.9% for hypermenorrhea, and 12.0% for abnormal cycle length. This study suggests that women in the military report less day-to-day job stress but more atypical life events, including those related to their jobs, and that these life events are associated with adverse menstrual consequences.

What is the potential measurement error in occupational exposure studies?

This paper demonstrates statistical methods that estimate measurement error from available industrial hygiene data. Errors in measuring a continuous exposure variable may arise when all individuals in a work area are assigned the same exposure. An example is when the mean of exposure measurements obtained on a sample of individuals is assigned to all workers with similar jobs. This may lead to inaccurate point and interval estimates in exposure-response modeling. A method of simulating the distribution of true (i.e., unobserved) individual exposures is described in order to estimate the mean and variance of measurement error. The minimum variance unbiased estimator approximates the mean of lognormally distributed exposure measurements. The distribution of true individual exposures is approximated by the distribution of simulated estimates of mean exposure. The methodology is illustrated by exposure data from work areas manufacturing refractory ceramic fiber (RCF) and RCF products. Results show that exposure is slightly underestimated in work areas with between 25 and 113 exposure measurements; measurement error variance averages about 1.3% of the total variance.

Workshop to identify critical windows of exposure for children's health: reproductive health in children and adolescents work group summary.

This work group report addresses the central question: What are the critical windows during development (preconception through puberty) when exposure to xenobiotics may have the greatest adverse impact on subsequent reproductive health? The reproductive system develops in stages, with sex-specific organogenesis occurring prenatally and further maturational events occurring in the perinatal period and at puberty. Complex endocrine signals as well as other regulatory factors (genetics, growth factors) are involved at all stages. Evidence from animal models and human studies indicates that many specific events can be perturbed by a variety of toxicants, with endocrine-mediated mechanisms being the more widely studied. Prioritized research needs include basic studies on the cellular-molecular and endocrine regulation of sexual differentiation and development; increased efforts regarding potential adverse effects on development in females, including breast development; expanded animal studies on different classes of chemicals, comparing responses during development (prenatal and postnatal) with responses in adults; and, more extensive explorations regarding the reproductive biology and toxicology of puberty in humans.

Weight change and lung function: implications for workplace surveillance studies.

This study evaluated the relationship between weight change and longitudinal measurement of lung function among 361 men providing at least five pulmonary function tests. The men in this study were participants in a workplace pulmonary surveillance program for subjects with exposure to refractory ceramic fibers (RCFs). Occupational and environmental studies are generally designed to evaluate factors suspected of causing excess decline in lung function. Failure to adequately account for all significant factors may lead to erroneous conclusions regarding change in lung function. This study utilized two different statistical models to evaluate longitudinal changes in a cohort of RCF workers. What was unique to this study was the modeling of longitudinally measured initial weight, weight change, and longitudinal exposure before and during the period of observation. Results showed a strong relationship between weight gain and longitudinal loss in lung function that approximated forced vital capacity declines of 16 mL for every kilogram of weight gain per year in both models. This value is comparable or greater in magnitude and significance to other factors known to be inversely related to lung function, such as age and pack-years smoking to time of initial testing. In conclusion, weight gain was found to have a significant impact on longitudinal change in lung function. Therefore, weight gain becomes a very important variable that requires consideration whenever longitudinal studies of pulmonary function are conducted.

Potential significance of airborne fiber dimensions measured in the U.S. refractory ceramic fiber manufacturing industry.

BACKGROUND: To determine dimensions of airborne fibers in the U.S. refractory ceramic fiber (RCF) manufacturing industry, fibers collected through personal air sampling for employees at RCF manufacturing and processing operations have been measured. METHODS: Data were derived from transmission electron microscopy analyses of 118 air samples collected over a 20-year period. RESULTS: Characteristics of sized fibers include: diameter measurements of <60; 0.19 to 1.0 micron, m of which 75% are less than 0.6 micron and length ranging from < 0.6 to > 20 micron, with 68% of fibers between 2.4 and 20 micron. CONCLUSIONS: Exposures in RCF manufacturing include airborne fibers with dimensions (diameter < 0.1-0.4 micron, length < 10 micron) historically associated with biological effects in pleural tissues. Air sampling data and a review of studies relating fiber size to pleural effects in animals and humans support the belief that information on fiber dimensions is essential for studies with synthetic vitreous fibers.

Male reproductive effects of solvent and fuel exposure during aircraft maintenance.

Few studies have addressed the effects of mixed, low-level exposures to complex mixtures on a man's reproductive potential. In this prospective study, each subject was evaluated before first exposure and at 15 and 30 weeks after exposures had begun. A total of 50 men working on aircraft maintenance at an Air Force installation were included in the study. In addition, eight unexposed men were concurrently sampled. Industrial hygiene (IH) sampling and expired breath samples were collected for jet fuel as measured by total napthas, benzene--a component of jet fuel, 1,1,1-trichloroethane, methyl ethyl ketone, xylenes, toluene, and methylene chloride. Sperm production, structure, and function (sperm concentration, sperm motion, viability, morphology, morphometrics, and stability of sperm chromatin) were evaluated. Exposures were low. All mean IH measures were below 6 ppm, which is less than 10% of the Occupational Safety and Health Administration standard for all chemicals except benzene. Sheet metal workers had the highest mean breath levels for both total solvents (24 ppb) and fuels (28.3 ppb). For most sperm measures, mean values remained in the normal range throughout the 30 weeks of exposure. When jobs were analyzed by exposure groups, some adverse changes were observed. The paint shop group had a significant decline in motility of 19.5% at 30 weeks. Internal dose measures, however, did not show a significant association with spermatogenic changes.

Comparison of internal dose measures of solvents in breath, blood and urine and genotoxic changes in aircraft maintenance personnel.

Solvents and fuels are in widespread use both in civilian and military populations. 1,1,1-trichloroethane (TCA), xylene, toluene, methyl ethyl ketone (MEK) and methylene chloride are found in a variety of compounds including degreasing agents, paints, coatings, pesticides and paint strippers. Toluene and xylene are also found in fuels, which are complex mixtures of hundreds of agents. The purpose of this investigation was twofold. The first was to determine the optimum medium to measure internal dose of solvents comparing blood, urine and breath. The second was to determine if low level exposures were associated with genotoxic changes after a short-term exposure of fifteen or thirty weeks. To accomplish the first goal a pilot study was initiated involving eight volunteers who worked in aircraft maintenance including sheet metal, painting and assembly mechanic jobs. Industrial hygiene measurements were evaluated over 30 working days. Breath, blood and a 24-hour urine sample were collected twice to compare internal dose parameters. To achieve the second goal, 58 newly hired subjects were monitored prior to exposure and over 30 weeks to determine if there were genotoxic changes as a result of solvent and/or fuel exposure as measured by sister chromatid exchanges (SCEs) and micronuclei (MN). Exposure groups included workers involved in sheet metal (fuel cell) activities, painting, fueling operations and flight line. Results of the pilot study demonstrated that industrial hygiene air samples and internal breath measures taken on the same day were highly correlated for measuring TCA (r = 0.93) and toluene (r = 0.90) but was not as well correlated for the other compounds. Breath measures were more sensitive for measuring low level exposure than were either analytes in blood or 24-hour urine samples; these latter two measures were usually below the limit of detection. A small but statistically significant increase in the frequency of SCEs occurred after 30 weeks of exposure for sheet metal workers (p = 0.003) and for painters (p = 0.05). The MN frequency in the sheet metal workers initially showed a significant increase by 15 weeks, but by 30 weeks had decreased. Chance occurrence of exposures to other occupational or non-occupational agents can not be eliminated as a cause of the genotoxic results since between 58 and 93 total analytes could be found in the breath of some aircraft maintenance personnel.

Development and evaluation of a microprocessor-based ergonomic dosimeter for evaluating carpentry tasks.

This portable and self-contained lightweight microprocessor based Ergonomic Dosimeter is designed to collect continuously postural angles of the torso and the upper arm in the sagittal plane and the number of kneeling activities. Up to 4 h of task performance data can be stored in a non-volatile memory of the dosimeter, which can then be downloaded to a lap-top computer. The portable dosimeter was tested for test-retest reliability, compared with posture data obtained with a computer-based video analysis system and evaluated at a carpenter's apprentices school and at a construction site. The dosimeter was shown to be suitable for collecting posture and kneeling data for a prolonged period at construction sites.

An industry-wide pulmonary study of men and women manufacturing refractory ceramic fibers.

An industry-wide pulmonary morbidity study was undertaken to evaluate the respiratory health of employees manufacturing refractory ceramic fibers at five US sites between 1987 and 1989. Refractory ceramic fibers are man-made vitreous fibers used for high temperature insulation. Of the 753 eligible current employees, 742 provided occupational histories and also completed the American Thoracic Society respiratory symptom questionnaire; 736 also performed pulmonary function tests. Exposure to refractory ceramic fibers was characterized by classifying workers as production or nonproduction employees and calculating the duration of time spent in production employment. The risk of working in the production of refractory ceramic fibers and having one or more respiratory symptoms was estimated by adjusted odds ratios and found to be 2.9 (95 percent confidence interval 1.4-6.2) for men and 2.4 (95 percent confidence interval 1.1-5.3) for women. The effect of exposure to refractory ceramic fibers on forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), the ratio of the two (FEV1/FVC), and forced expiratory flow (liters/second) between 25 percent and 75 percent of the FVC curve (FEF(25-75)) was evaluated by multiple regression analysis using transformed values adjusted for height, by dividing by the square of each individual's height. For men, there was a significant decline in FVC for current and past smokers of 165.4 ml (p < 0.01) and 155.5 ml (p = 0.04), respectively, per 10 years of work in the production of refractory ceramic fibers. For FEV1, the decline was significant (p < 0.01) only for current smokers at 134.9 ml. For women, the decline was greater and significant for FVC among nonsmokers, who showed a decrease of 350.3 ml (p = 0.05) per 10 years of employment in the production of refractory ceramic fibers. These findings indicate that there may be important sex differences in response to occupational and/or environmental exposure.

Prevalence of work related musculoskeletal disorders in active union carpenters.

OBJECTIVES: To determine the prevalence and risk factors for work related musculoskeletal disorders among union carpenters. METHODS: A detailed questionnaire on musculoskeletal symptoms and work history was administered to 522 carpenters. The symptom questions assessed if carpenters experienced pain, numbness, or tingling in a particular body region. A subset of this group then received a physical examination of the upper extremities and knees. RESULTS: The study group was primarily white (94.9%) and male (97.8%) with a mean age of 42.3 years. The highest prevalence of work related musculoskeletal disorders cases by carpentry specialty ranged from 20%-24% for those doing drywall or ceiling, finishing or framing, and the building of concrete forms. Generally, as duration of employment increased, the prevalence of symptoms increased. An adjusted logistic regression analysis showed that the group with the longest (> or = 20 years) duration of employment in carpentry was significantly associated with work related musculoskeletal disorders of the shoulders (odds ratio (OR) 3.2, 95% confidence interval (95% CI) 1.1 to 8.9), hands or wrists (OR 3.1, 95% CI 1.1 to 8.4), and knees (OR 3.5, 95% CI 1.3 to 9.2). Also, analyses showed that carpenters who reported that they had little or no influence over their work schedule had significant increases of work related musculoskeletal disorders of the shoulders, hips, and knees with ORs of 1.9 (95% CI 1.1 to 3.2), 2.9 (95% CI 1.1 to 7.2), and 2.3 (95% CI 1.2 to 4.1), respectively. Feeling exhausted at the end of day was also a significant risk factor for work related musculoskeletal disorders of the knee (OR 1.8, 95% CI 1.1 to 3.1). Upper extremity disorders were the most prevalent work related musculoskeletal disorders reported among all carpenters. Drywall or ceiling activities involve a considerable amount of repetitive motion and awkward postures often with arms raised holding heavy dry walls in place, whereas form work is notable for extensive lumbar flexion and had the two highest rates of work related musculoskeletal disorders. The psychosocial element of job control was associated with both upper and lower extremity disorders. These union carpenters, who were relatively young, already were experiencing considerable work related physical problems. CONCLUSION: This study supports the need for vigilant ergonomic intervention at job sites and early ergonomic education as an integral part of apprenticeship school training to ensure that carpenters remain fit and healthy throughout their working lifetime.