Bacteria in a water-damaged building: associations of actinomycetes and non-tuberculous mycobacteria with respiratory health in occupants.

We examined microbial correlates of health outcomes in building occupants with a sarcoidosis cluster and excess asthma. We offered employees a questionnaire and pulmonary function testing and collected floor dust and liquid/sludge from drain tubing traps of heat pumps that were analyzed for various microbial agents. Forty-nine percent of participants reported any symptom reflecting possible granulomatous disease (shortness of breath on exertion, flu-like achiness, or fever and chills) weekly in the last 4 weeks. In multivariate regressions, thermophilic actinomycetes (median = 529 CFU/m2 ) in dust were associated with FEV1 /FVC [coefficient = -2.8 per interquartile range change, P = 0.02], percent predicted FEF25-75% (coefficient = -12.9, P = 0.01), and any granulomatous disease-like symptom [odds ratio (OR) = 3.1, 95% confidence interval (CI) = 1.45-6.73]. Mycobacteria (median = 658 CFU/m2 ) were positively associated with asthma symptoms (OR = 1.5, 95% CI = 0.97-2.43). Composite score (median = 11.5) of total bacteria from heat pumps was negatively associated with asthma (0.8, 0.71-1.00) and positively associated with FEV1 /FVC (coefficient = 0.44, P = 0.095). Endotoxin (median score = 12.0) was negatively associated with two or more granulomatous disease-like symptoms (OR = 0.8, 95% CI = 0.67-0.98) and asthma (0.8, 0.67-0.96). Fungi or (1→3)-ß-D-glucan in dust or heat pump traps was not associated with any health outcomes. Thermophilic actinomycetes and non-tuberculous mycobacteria may have played a role in the occupants' respiratory outcomes in this water-damaged building.

Work-related peak flow and asthma symptoms in a damp building.

BACKGROUND: Working in damp conditions is associated with asthma, but few studies have used objective testing to document work-related patterns. AIMS: To describe the relationship of peak flow measurements to work-related asthma (WRA) symptoms and WRA among occupants in a damp office building. METHODS: At the beginning of the study, all workers were offered a questionnaire and methacholine challenge testing. Participants were then instructed to perform serial spirometry using handheld spirometers five times per day over a 3 week period. Peak flow data were analysed using OASYS-2 software. We calculated the area between the curves (ABC score) using hours from waking. We considered a score >5.6 L/min/h to be indicative of a work-related pattern. RESULTS: All 24 employees participated in the questionnaire. Seven participants (29%) reported physician-diagnosed asthma with onset after starting work in the building. Almost two-thirds (63%) of participants reported at least one lower respiratory symptom (LRS) occurring one or more times per week in the last 4 weeks. Twenty-two (92%) consented to participate in serial spirometry. Fourteen participants had adequate quality of serial spirometry, five of whom had ABC scores >5.6, ranging from 5.9-23.0. Of these five, two had airways responsiveness, three had current post-hire onset physician-diagnosed asthma and four reported work-related LRS. CONCLUSIONS: We found evidence of work-related changes in serial peak flows among some occupants of an office building with a history of dampness. Serial peak flows may be a useful measure to determine WRA in office settings.

Rhinosinusitis and mold as risk factors for asthma symptoms in occupants of a water-damaged building.

UNLABELLED: Mold exposure in damp buildings is associated with both nasal symptoms and asthma development, but the progression of building-related (BR) rhinosinusitis symptoms to asthma is unstudied. We examined the risk of developing BR-asthma symptoms in relation to prior BR-rhinosinusitis symptoms and microbial exposure among occupants of a damp building. We conducted four cross-sectional health and environmental surveys among occupants of a 20-story water-damaged office building. We defined BR-rhinosinusitis symptom (N=131) and comparison (N=361) groups from participants' first questionnaire responses. We compared the odds for the development of BR-asthma symptoms between these two groups over the subsequent surveys, using logistic regression models adjusted for demographics, smoking, building tenure, and first-survey exposures to fungi, endotoxin, and ergosterol. The BR-rhinosinusitis symptom group had higher odds for developing BR-asthma symptoms [odds ratio (OR)=2.2; 95% confidence interval (CI)=1.3-3.6] in any subsequent survey compared to those without BR-rhinosinusitis symptoms. The BR-rhinosinusitis symptom group with higher fungal exposure within the building had an OR of 7.4 (95% CI=2.8-19.9) for developing BR-asthma symptoms, compared to the lower fungal exposure group without BR-rhinosinusitis symptoms. Our findings suggest that rhinosinusitis associated with occupancy of water-damaged buildings may be a sentinel for increased risk for asthma onset in such buildings. PRACTICAL IMPLICATIONS: Exposure to mold is associated with the development of asthma in damp building occupants, and rhinitis is known to be a risk factor for asthma. However, there is little information about the degree of risk for the progression of rhinosinusitis to asthma owing to mold exposures in damp buildings. Our study of damp building occupants demonstrates that building-related (BR) rhinosinusitis symptoms were a risk factor for the development of BR asthma symptoms and that exposure to mold (fungi) or other dampness-related agents augments risk for the development of BR asthma symptoms among those with BR rhinosinusitis symptoms. Our findings suggest that occurrence of BR upper respiratory illness in water-damaged buildings may presage future endemic asthma.

Levels of microbial agents in floor dust during remediation of a water-damaged office building.

UNLABELLED: We examined the effects of remediation on loads of culturable fungi in floor dust collected from a large water-damaged office building during four cross-sectional surveys (2002, 2004, 2005, and 2007, respectively). We created a binary remediation variable for each year for each sampled workstation using information on remediation associated with water damage obtained from building management and used generalized linear mixed-effects models. We found significantly lower levels of culturable total and hydrophilic fungi at remediated workstations than at non-remediated workstations in 2004 and 2005 after completion of major remediation. The remediation effect, however, disappeared in 2007. The fraction of hydrophilic to total fungal concentrations was lowest in 2004, increased in 2005, and was highest in 2007. Our results indicate that the 2003 remediation lowered dust indices of dampness temporarily, but remediation was incomplete, consistent with a building assessment report of water infiltration. This study demonstrates the utility of longitudinal evaluation of microbial indices during remediation of water damage in this building, in which elimination of sources of moisture was not fully addressed. Our findings indicate that the fraction of hydrophilic fungi derived from concentrations of fungal species may be a useful index for assessing the long-term effectiveness of remediation. PRACTICAL IMPLICATIONS: This study demonstrates the utility of longitudinal evaluation of microbial indices during remediation of water damage in this building, in which elimination of sources of moisture was incomplete. Our findings indicate that the fraction of hydrophilic fungi derived from concentrations of fungal species may be a useful index for assessing the long-term effectiveness of remediation.

Occupational sensitization to soy allergens in workers at a processing facility.

BACKGROUND: Exposure to soy antigens has been associated with asthma in community outbreaks and in some workplaces. Recently, 135 soy flake processing workers (SPWs) in a Tennessee facility were evaluated for immune reactivity to soy. Allergic sensitization to soy was common and was five times more prevalent than in health care worker controls (HCWs) with no known soy exposure. OBJECTIVE: To characterize sensitization to soy allergens in SPWs. METHODS: Sera that were positive to soy ImmunoCAP (n=27) were tested in IgE immunoblots. Wild-type (WT) and transgenic (TG) antigens were sequenced using nanoscale Ultra-Performance Liquid Chromatography Tandem Mass Spectrometry (nanoUPLC MS/MS). IgE reactivity towards 5-enolpyruvylshikimate-3-phosphate synthase (CP4-EPSP), a protein found in TG soy, was additionally investigated. De-identified sera from 50 HCWs were used as a control. RESULTS: Immunoblotting of WT and TG soy flake extracts revealed IgE against multiple soy antigens with reactivity towards 48, 54, and 62 kDa bands being the most common. The prominent proteins that bound SPW IgE were identified by nanoUPLC MS/MS analysis to be the high molecular weight soybean storage proteins, ß-conglycinin (Gly m 5), and Glycinin (Gly m 6). No specific IgE reactivity could be detected to lower molecular weight soy allergens, Gly m 1 and Gly m 2, in soybean hull (SH) extracts. IgE reactivity was comparable between WT and TG extracts; however, IgE antibodies to CP4-EPSP could not be detected. CONCLUSIONS AND CLINICAL RELEVANCE: SPWs with specific IgE to soy reacted most commonly with higher molecular weight soybean storage proteins compared with the lower molecular weight SH allergens identified in community asthma studies. IgE reactivity was comparable between WT and TG soy extracts, while no IgE reactivity to CP4-EPSP was observed. High molecular weight soybean storage allergens, Gly m 5 and Gly m 6, may be respiratory sensitizers in occupational exposed SPWs.

Occupational distribution of persons with confirmed 2009 H1N1 influenza.

OBJECTIVE: To assess the distribution of illness by industry sector and occupation reflected in early 2009 H1N1 influenza surveillance. METHODS: We analyzed data reported for April to July 2009, for 1361 laboratory-confirmed 2009 H1N1 influenza-infected persons 16 years or older, with work status information from four states. A North American Industry Classification System 2007 code was assigned to each employed person. For a subset, an occupation code was assigned. RESULTS: Of 898 employed individuals, 611 (68.0%) worked in the non-health care sector. The largest proportions worked in public administration, educational services, and accommodation and food services. In Wisconsin health care personnel, 53.6% were paraprofessionals, 33.6% professionals, and 12.7% other workers; 26.9% worked in ambulatory settings, 46.2% in hospitals, and 26.9% in nursing or residential care facilities. CONCLUSIONS: Our findings suggest that industry sectors and occupations should be explored systematically in future influenza surveillance.

Adverse respiratory outcomes associated with occupational exposures at a soy processing plant.

This study aimed to characterise the relationship between adverse health outcomes and occupational risk factors among workers at a soy processing plant. A questionnaire, spirometry, methacholine challenge, immune testing and air sampling for dust and soy were offered. Prevalence ratios (PRs) of respiratory problems from comparisons with the US adult population were calculated. Soy-specific immunoglobulin (Ig)G and IgE among participants and healthcare worker controls were compared. Associations between health outcomes and potential explanatory variables were examined using logistic regression. 147 (52%) out of 281 employees, including 66 (70%) out of 94 production workers, participated. PRs were significantly elevated for wheeze, sinusitis, ever-asthma and current asthma. Participants had significantly higher mean concentrations of soy-specific IgG (97.9 mg·L(-1) versus 1.5 mg·L(-1)) and prevalence of soy-specific IgE (21% versus 4%) than controls. Participants with soy-specific IgE had three-fold greater odds of current asthma or asthma-like symptoms, and six-fold greater odds of work-related asthma-like symptoms; the latter additionally was associated with production work and higher peak dust exposures. Airways obstruction was associated with higher peak dust. Work-related sinusitis, nasal allergies and rash were associated with reported workplace mould exposure. Asthma and symptoms of asthma, but not other respiratory problems, were associated with immune reactivity to soy.

Asthma and respiratory symptoms in hospital workers related to dampness and biological contaminants.

UNLABELLED: The National Institute for Occupational Safety and Health investigated respiratory symptoms and asthma in relation to damp indoor environments in employees of two hospitals. A cluster of six work-related asthma cases from one hospital department, whose symptoms arose during a time of significant water incursions, led us to conduct a survey of respiratory health in 1171/1834 employees working in the sentinel cases hospital and a nearby hospital without known indoor environmental concerns. We carried out observational assessment of dampness, air, chair, and floor dust sampling for biological contaminants, and investigation of exposure-response associations for about 500 participants. Many participants with post-hire onset asthma reported diagnosis dates in a period of water incursions and renovations. Post-hire asthma and work-related lower respiratory symptoms were positively associated with the dampness score. Work-related lower respiratory symptoms showed monotonically increasing odds ratios with ergosterol, a marker of fungal biomass. Other fungal and bacterial indices, particle counts, cat allergen and latex allergen were associated with respiratory symptoms. Our data imply new-onset of asthma in relation to water damage, and indicate that work-related respiratory symptoms in hospital workers may be associated with diverse biological contaminants. PRACTICAL IMPLICATIONS: In healthcare facilities with indoor dampness and microbial contamination, possible associations between such conditions and respiratory health effects should be considered. Good building maintenance and housekeeping procedures should lead to improvements in employee respiratory health.

Sarcoidosis, asthma, and asthma-like symptoms among occupants of a historically water-damaged office building.

UNLABELLED: Sarcoidosis is a granulomatous disease of unknown etiology with evidence of association with exposure to microbial agents. In June 2006, we investigated a sarcoidosis cluster among office workers in a water-damaged building. In the course of the investigation, we became aware of a high rate of respiratory complaints including asthma and asthma-like symptoms. We conducted case finding for physician-diagnosed sarcoidosis and asthma and administered a health questionnaire survey and pulmonary function tests (PFTs) to consenting occupants. We compared prevalence ratios (PRs) to the Environmental Protection Agency's Building Assessment Survey and Evaluation study (BASE) and the National Health and Nutrition Examination Survey (NHANES). We identified six sarcoidosis cases. The current building prevalence is 2206 cases/100,000 population, elevated, compared with the US population range of <1-40 cases/100,000. Of current occupants, 77% (105) participated in the health questionnaire survey and 64% (87) in PFTs. Physician-diagnosed asthma was elevated, compared with the US adult population. Adult asthma incidence was 3.3/1000 person-years during the period before building occupancy and 11.5/1000 person-years during the period after building occupancy. Comparisons with US office workers (BASE) yielded elevated PRs for shortness of breath [PR, 9.6; 95% confidence interval (CI), 6.1-15.2], wheeze (PR, 9.1; 95% CI 5.6-14.6), and chest tightness (PR, 5.1; 95% CI 2.8-9.0). PFT results supported reports of respiratory symptoms and diagnoses. Based on our findings building occupants were relocated. PRACTICAL IMPLICATIONS: The remission of occupational asthma caused by certain known antigens improves with early diagnosis and removal from exposure. As a suspected antigen-mediated disease, sarcoidosis might also benefit if affected persons are isolated from continued exposure. Our investigation identified a high prevalence of new-onset sarcoidosis, and asthma among workers of a water damaged building with a history of indoor environmental quality complaints. Removal of all individuals from such environments until completion of building diagnostics, environmental sampling and complete remediation is a prudent measure when feasible.

Fungal and endotoxin measurements in dust associated with respiratory symptoms in a water-damaged office building.

UNLABELLED: We investigated the associations of fungal and endotoxin levels in office dust with respiratory health in 888 (67% participation) occupants of a water-damaged building. We analyzed floor and chair dusts from 338 workstations for culturable fungi and endotoxin. Based on averages, we ranked each floor of the building as low, medium, or high for occupants' exposure to each of these agents. Multivariate logistic regression models for building-related symptoms included this ranking of fungi and endotoxin, age, gender, race, smoking status, and duration of occupancy. Using floor dust measures, we found significantly increased odds for lower respiratory symptoms [wheeze, chest tightness, attacks of shortness of breath, and attacks of cough: odds ratios (OR) = 1.7 (95% confidence interval (CI): 1.02-2.77) to 2.4 (95% CI: 1.29-4.59)], throat irritation [OR = 1.7, (95% CI: 1.06-2.82)], and rash/itchy skin [OR = 3.0, (95% CI: 1.47-6.19)] in the highest fungal exposure group compared to the lowest, with generally linear exposure-response relationships. Nonlinear relationships were observed for many of these symptoms and endotoxin in floor dust. Interaction models showed that endotoxin modified effects of fungi on respiratory symptoms. Our findings of exposure interactions and exposure-response relationships of fungal and endotoxin with increased risk of building-related symptoms contribute to an understanding of the role of microbial agents in building-related asthma and respiratory and systemic symptoms. PRACTICAL IMPLICATIONS: Our demonstration of exposure-response relationships between measurements of fungi and/or endotoxin in floor dusts and building-related symptoms implies that microbial agents in floor dust may be a good surrogate measure for dampness-related bioaerosol exposure, considering that measurements of microbial agents in air often fail to demonstrate the associations between exposure and health. In addition, our finding that endotoxin exposure may change the effect of fungal exposure (and vice versa) on respiratory heath suggests that exposure to both fungi and endotoxin should be assessed in epidemiological investigations examining the effect of fungal or endotoxin exposure on respiratory health in indoor environments.

Building-related respiratory symptoms can be predicted with semi-quantitative indices of exposure to dampness and mold.

UNLABELLED: Using a semi-quantitative mold exposure index, the National Institute for Occupational Safety and Health (NIOSH) investigated 13 college buildings to examine whether building-related respiratory symptoms among employees are associated with environmental exposure to mold and dampness in buildings. We collected data on upper and lower respiratory symptoms and their building-relatedness, and time spent in specific rooms with a self-administered questionnaires. Trained NIOSH industrial hygienists classified rooms for water stains, visible mold, mold odor, and moisture using semi-quantitative scales and then estimated individual exposure indices weighted by the time spent in specific rooms. The semi-quantitative exposure indices significantly predicted building-related respiratory symptoms, including wheeze [odds ratio (OR) = 2.3; 95% confidence interval (CI) = 1.1-4.5], chest tightness (OR = 2.2; 95% CI = 1.1-4.6), shortness of breath (OR = 2.7; 95% CI = 1.2-6.1), nasal (OR = 2.5; 95% CI = 1.3-4.7) and sinus (OR = 2.2; 95% CI = 1.2-4.1) symptoms, with exposure-response relationships. We found that conditions suggestive of indoor mold exposure at work were associated with building-related respiratory symptoms. Our findings suggest that observational semi-quantitative indices of exposure to dampness and mold can support action to prevent building-related respiratory diseases. PRACTICAL IMPLICATIONS: Current air sampling methods have major limitations in assessing exposure to mold and other biological agents that may prevent the demonstration of associations of bioaerosol exposure with health. Our study demonstrates that semi-quantitative dampness/mold exposure indices, based solely on visual and olfactory observation and weighted by time spent in specific rooms, can predict existence of excessive building-related respiratory symptoms and diseases. Relative extent of water stains, visible mold, mold odor, or moisture can be used to prioritize remediation to reduce potential risk of building-related respiratory diseases. From a public health perspective, these observational findings justify action to correct water leaks and repair water damage in order to prevent building-related respiratory diseases. This approach can also be a basis for developing practical building-diagnostic tools for water-incursion.

Bronchiolitis obliterans syndrome in popcorn production plant workers.

Following sentinel case recognition, an excess of fixed airways obstruction was found among current workers in a microwave popcorn plant associated with butter flavouring exposures. In order to characterise the clinical presentation of sentinel cases, the medical records of sentinel cases were reviewed, interviews conducted and serial spirometric testing performed. Cases worked in microwave popcorn production, and five of the nine cases had mixed flavourings. Most had never smoked or smoked minimally. Cases showed onset of cough, shortness of breath and wheezing 5 months to 9 yrs after starting work at the popcorn plant. Initial forced expiratory volume in one second ranged 14.0-66.8% of the predicted value. Eight high-resolution computed tomography scans showed marked bronchial wall thickening and mosaic attenuation with air trapping. Open lung biopsy results were consistent with, or diagnostic of, constrictive bronchiolitis in two of three cases. Five cases are on lung transplantation waiting lists. After leaving employment, nearly all cases experienced stabilisation of their lung function within 2 yrs. Astute clinicians can help identify new causes of airways obstruction by alerting public health authorities to unexplained disease cases occurring in groups of workers.

Respiratory symptoms among crab processing workers in Alaska: epidemiological and environmental assessment.

BACKGROUND: Crab processing workers may develop respiratory symptoms and specific IgE responses, but the risk factors have not been fully described. METHODS: In 1998, 107 workers at a crab processing facility completed a survey both at the beginning and end of the processing season. The surveys included standardized symptom questionnaires, spirometry, and serological testing, as well as measurement of workplace airborne crab allergens and microscopic analysis of aerosolized materials. RESULTS: Over the crab processing season, asthma-like symptoms developed in 26% of study participants and bronchitic symptoms in 19%. Only 9% of those with new asthma-like symptoms were IgE-sensitized to crab at the end of the season. Among the crab processing jobs, butchering and degilling workers had the highest incidence of respiratory symptoms. CONCLUSIONS: Both personal and process-related factors appear to affect the development of respiratory symptoms in crab processing workers. In this study, crab specific IgE was not detected in most of the workers with new symptoms. Published 2001 Wiley-Liss, Inc.

Beryllium sensitization and disease among long-term and short-term workers in a beryllium ceramics plant.

OBJECTIVE: Workers at a beryllium ceramics plant were tested for beryllium sensitization and disease in 1998 to determine whether the plant-wide prevalence of sensitization and disease had declined since the last screening in 1992; an elevated prevalence was associated with specific processes or with high exposures; exposure-response relationships differed for long-term workers hired before the last plant-wide screening and short-term workers hired since then. METHODS: Current workers were asked to complete a questionnaire and to provide blood for the beryllium lymphocyte proliferation test (BeLPT). Those with an abnormal BeLPT were classified as sensitized, and were offered clinical evaluation for beryllium disease. Task- and time-specific measurements of airborne beryllium were combined with individual work histories to compute mean, cumulative, and peak beryllium exposures for each worker. RESULTS: The 151 participants represented 90% of 167 eligible workers. Fifteen (9.9% of 151) had an abnormal BeLPT and were split between long-term workers (8/77 = 10.4%) and short-term workers (7/74 = 9.5%). Beryllium disease was detected in 9.1% (7/77) of long-term workers but in only 1.4% (1/74) of short-term workers (P = 0.06), for an overall prevalence of 5.3% (8/151). These prevalences were similar to those observed in the earlier survey. The prevalence of sensitization was elevated in 1992 among machinists, and was still elevated in 1998 among long-term workers (7/40 = 18%) but not among short-term workers (2/36 = 6%) with machining experience. The prevalence of sensitization was also elevated in both groups of workers for the processes of lapping, forming, firing, and packaging. The data suggested a positive relationship between peak beryllium exposure and sensitization for long-term workers and between mean, cumulative, and peak exposure and sensitization for short-term workers, although these findings were not statistically significant. Long-term workers with either a high peak exposure or work experience in forming were more likely to have an abnormal BeLPT (8/51 = 16%) than the other long-term workers (0/26, P = 0.05). All seven sensitized short-term workers either had high mean beryllium exposure or had worked longest in forming or machining (7/55 = 13% versus 0/19, P = 0.18). CONCLUSIONS: A plant-wide decline in beryllium exposures between the 1992 and 1998 surveys was not matched by a decline in the prevalence of sensitization and disease. Similar to findings from other studies, beryllium sensitization/disease was associated with specific processes and elevated exposures. The contrast in disease prevalence between long-term and short-term workers suggests that beryllium sensitization can occur after a short period of exposure, but beryllium disease usually requires a longer latency and/or period of exposure. The findings from this study motivated interventions to more aggressively protect and test workers, and new research into skin exposure as a route of sensitization and the contribution of individual susceptibility.

Epidemiologic investigation of respiratory morbidity at a nylon flock plant.

BACKGROUND: A cluster of biopsy-confirmed interstitial lung disease among workers at a nylon flock plant led to a request for National Institute for Occupational Safety and Health investigators to conduct a health hazard evaluation. METHODS: Part of the overall evaluation, reported here, involved a cross-sectional medical survey of current employees. The survey consisted of a questionnaire, spirometry and diffusing capacity testing, and chest radiograph. RESULTS: Workers assigned to production and maintenance jobs reported frequent eye and throat irritation, respiratory symptoms, and systemic symptoms (i.e., generalized aches and fevers). Most reported improvement when away from work. Frequent respiratory/systemic symptom prevalence was significantly associated with departmental category, with days and hours worked per week, and with working on a flocking range. Compared to asymptomatic workers, symptomatic workers had similar mean ratios of forced expiratory volume in one second to forced vital capacity, but lower mean percent of predicted values for both forced vital capacity and diffusing capacity. All acceptable chest radiographs were classified as category 0 for small opacities. CONCLUSIONS: Findings of this study, along with those from studies reported elsewhere, implicate occupational exposure to flock-associated dust as a significant respiratory health hazard at this plant.

Analysis of construction injury burden by type of work.

BACKGROUND: To lay groundwork for identifying patterns of injury etiology, we sought to describe injury experience associated with types of work performed at construction sites by examining workers' compensation (WC) claims for the 32,081 construction workers who built Denver International Airport (DIA). METHODS: Injury rates and WC payment rates were calculated for 25 types of work based on claims and payroll data reported to DIA's owner-controlled insurance program according to National Council on Compensation Insurance job classifications. By linking DIA claims with corresponding lost-work-time (LWT) claims filed with Colorado's Workers' Compensation Division, we were also able to obtain and examine both total and median lost days for each type of work. RESULTS: Injury experience varied widely among the types of construction work. Workers building elevators and conduits and installing glass, metal, or steel were at particularly high risk of both LWT and non-LWT injury. Median days lost by injured workers was highest (202 days) for driving/trucking. Median days lost for most types of work was much greater than previously reported for construction: 40 days or more for 18 of the 25 types of work analyzed. WC payment rates reflect both number and severity of injuries and were generally not significantly different from expected losses. They were, however, significantly higher than expected for driving/trucking, metal/steel installation, inspection/analysis, and elevator construction. CONCLUSIONS: Analysis of injury data by type of work allows targeting of safety resources to high risk construction work and would be useful in prospective surveillance at large construction sites with centrally administered workers' compensation plans.

Nylon flock-associated interstitial lung disease.

A work-related interstitial lung disease has been diagnosed in workers at five nylon flock facilities in three different states and a Canadian province. The National Institute for Occupational Safety and Health hosted a workshop at which consulting pulmonary pathologists reviewed lung tissue samples from all the cases for which lung biopsy material was available (15 of 20 cases known in January 1998). After independent review and scoring of these lung tissue specimens, the pathologists reached consensus that the histopathological findings revealed a characteristic lesion-a lymphocytic bronchiolitis and peribronchiolitis with lymphoid hyperplasia represented by lymphoid aggregates. The pathologists noted that the pathological findings were distinctive when compared with known lung conditions. The clinical presentation for the cases generally included cough, dyspnea, restrictive ventilatory defect with reduction in diffusing capacity, and interstitial markings on chest radiographs or high-resolution computed tomography (HRCT) scans. Six of the cases improved after removal from workplace exposure without medical treatment. Six others, who had recovered with medical treatment and removal from the workplace, had relapses in both symptoms and objective findings after attempting to return to nylon flock work. With this and other evidence supporting the existence of chronic interstitial pneumonitis associated with nylon flock processing, workshop participants recommended surveillance for early identification of affected workers and their removal from further workplace exposure.

An evaluation of the incidence of work-related asthma in the United States.

The objective of the study was to estimate the incidences of physician-diagnosed cases of work-related asthma (WRA) in Michigan and the entire United States. The statewide surveillance system for WRA in Michigan receives reports primarily from three sources: physicians, hospital discharge data, and worker's compensation claims. Knowledge of the overlap in reports from these sources was used in conjunction with capture-recapture methods to estimate the total number of diagnosed cases of WRA, and incidence rates were calculated using the estimated number of civilian employees in Michigan as the population at risk. For the entire United States, the product of a national incidence rate for asthma among adults and estimates of the proportion that is work-related was used. A total of 933 cases of WRA were reported to the Michigan surveillance program during 1988-1995, of which 904 were reported by at least one of the three main sources and equaled an average incidence of 27 cases/10(6)/year. This estimate was less than the range of estimates 58 to 204 cases/10(6)/year in Michigan arrived at using the capture-recapture methods. The national estimates of WRA ranged from 63 to 441 cases/10(6)/year. The authors' indirect estimates are closer to estimates from Canada, Sweden, and Finland than most existing direct estimates in the United States, but probably still underestimates the magnitude of WRA incidence because of the limitations of physician recognition of the work-relatedness of asthma among adults.

Contractor safety practices and injury rates in construction of the Denver International Airport.

BACKGROUND: We sought to explain the variation in injury rates found for categories of companies and contracts involved in the construction of the Denver International Airport (DIA) by surveying contractors about company and contract-level safety practices. METHODS: We conducted 213 telephone interviews (83% response) with representatives of contracts with payrolls of more than $250,000. We investigated the bivariate relationship between safety actions reported in the survey and injury occurrence by calculating the aggregate injury rates (lost work-time (LWT) rates and non-LWT rates) for the group of respondent contracts reporting always taking the action and for the group not always taking the action. Using Poisson regression, we examined the association between contract injury rates and contract safety practices while controlling for variables previously shown to affect contract-level injury rates. RESULTS: In Poisson regression, two actions, 1) disciplinary action always resulting when safety rules were violated and 2) always considering experience modification ratings when selecting subcontractors, were associated with lower LWT injury rates. Three actions or contract characteristics resulted in lower non-LWT rates: management always establishing goals for safety for supervisors, conducting drug testing at times other than badging or after an accident, and completing the DIA contract on budget, rather than over budget. Reportedly consistent use of a number of accepted safety practices was associated with significantly higher injury rates in bivariate and multivariate analyses. CONCLUSIONS: The pattern of counterintuitive results found in this study suggests that questions reflecting agreed-upon safety practices, when asked of the person responsible for all on-site construction activities, are likely to elicit normative responses. Objective validation of reported safety practices is critical to evaluating their efficacy in reducing injury rates, along with measures of both time at risk and outcome and control for prevailing risk of the work performed.

"Lifeguard lung": endemic granulomatous pneumonitis in an indoor swimming pool.

OBJECTIVES: Two sequential outbreaks of respiratory disease among lifeguards at an indoor swimming pool with water spray features were investigated. METHODS: Questionnaires were administered to recreation center employees following each outbreak. Respondents reporting 2 or more pool-related symptoms were offered clinical evaluation, including bronchoscopy with bronchoalveolar lavage and transbronchial biopsy. Pool air and water were sampled for fungi, bacteria, amoebae, endotoxin, and respirable particulates. RESULTS: Thirty-three lifeguards had noncaseating granulomas on biopsy and/or bronchoalveolar lavage lymphocytosis. Attack rates for the outbreaks were 27% and 65%. Case patients had higher cumulative hours of work and tended to work more hours per week. Analyses indicated increased levels of endotoxin in pool air and water (relative to control pools) and gram-negative bacterial colonization of water sprays. Use of water spray features generated a 5.2-fold increase in the number of respirable particles and up to an 8-fold increase in air endotoxin levels. CONCLUSIONS: Lifeguards in this indoor swimming pool developed granulomatous lung disease associated with endotoxin-containing respirable bioaerosols from water spray features, which ventilation system improvements did not prevent.