Electrostatic dust collectors compared to inhalable samplers for measuring endotoxin concentrations in farm homes

Paired electrostatic dust collectors (EDCs) and daily, inhalable button samplers (BS) were used concurrently to sample endotoxin in 10 farm homes during 7-day periods in summer and winter. Winter sampling included an optical particle counter (OPC) to measure PM2.5 and PM2.5-10 . Electrostatic dust collectors and BS filters were analyzed for endotoxin using the kinetic chromogenic Limulus amebocyte lysate assay. Optical particle counter particulate matter (PM) data were divided into two PM categories. In summer, geometric mean (geometric standard deviation) endotoxin concentrations were 0.82 EU/m(3) (2.7) measured with the BS and 737 EU/m(2) (1.9) measured with the EDC. Winter values were 0.52 EU/m(3) (3.1) for BS and 538 EU/m(2) (3.0) for EDCs. Seven-day endotoxin values of EDCs were highly correlated with the 7-day BS sampling averages (r = 0.70; P < 0.001). Analysis of variance indicated a 2.4-fold increase in EDC endotoxin concentrations for each unit increase of the ratio of PM2.5 to PM2.5-10 . There was also a significant correlation between BS and EDCs endotoxin concentrations for winter (r = 0.67; P < 0.05) and summer (r = 0.75; P < 0.05). Thus, EDCs sample comparable endotoxin concentrations to BS, making EDCs a feasible, easy to use alternative to BS for endotoxin sampling.

Contribution of solid fuel, gas combustion, or tobacco smoke to indoor air pollutant concentrations in Irish and Scottish homes

  There are limited data describing pollutant levels inside homes that burn solid fuel within developed country settings with most studies describing test conditions or the effect of interventions. This study recruited homes in Ireland and Scotland where open combustion processes take place. Open combustion was classified as coal, peat, or wood fuel burning, use of a gas cooker or stove, or where there is at least one resident smoker. Twenty-four-hour data on airborne concentrations of particulate matter<2.5 μm in size (PM2.5), carbon monoxide (CO), endotoxin in inhalable dust and carbon dioxide (CO2), together with 2-3 week averaged concentrations of nitrogen dioxide (NO2) were collected in 100 houses during the winter and spring of 2009-2010. The geometric mean of the 24-h time-weighted-average (TWA) PM2.5 concentration was highest in homes with resident smokers (99 μg/m3--much higher than the WHO 24-h guidance value of 25 μg/m3). Lower geometric mean 24-h TWA levels were found in homes that burned coal (7 μg/m3) or wood (6 μg/m3) and in homes with gas cookers (7 μg/m3). In peat-burning homes, the average 24-h PM2.5 level recorded was 11 μg/m3. Airborne endotoxin, CO, CO2, and NO2 concentrations were generally within indoor air quality guidance levels.

PRACTICAL IMPLICATIONS

Little is known about indoor air quality (IAQ) in homes that burn solid or fossil-derived fuels in economically developed countries. Recent legislative changes have moved to improve IAQ at work and in enclosed public places, but there remains a real need to begin the process of quantifying the health burden that arises from indoor air pollution within domestic environments. This study demonstrates that homes in Scotland and Ireland that burn solid fuels or gas for heating and cooking have concentrations of air pollutants generally within guideline levels. Homes where combustion of cigarettes takes place have much poorer air quality.

Early-life co-administration of cockroach allergen and endotoxin augments pulmonary and systemic responses

BACKGROUND

Environmental exposures to cockroach allergen and endotoxin are recognized epidemiological risk factors for the early development of allergies and asthma in children. Because of this, it is important to examine the role of early-life concurrent inhalation exposures to cockroach allergen and endotoxin in the pathogenesis of allergic airways disease.

OBJECTIVE

We examined the effects of repeated concomitant endotoxin and cockroach allergen inhalation on the pulmonary and systemic immune responses of newborn and juvenile mice.

METHODS

C3H/HeBFeJ mice were exposed to inhaled endotoxin and cockroach allergen via intranasal instillation from day 2 to 21 after birth, and systemic and pulmonary responses were examined in serum, bronchoalveolar lavage fluid, and lung tissue.

RESULTS

Cockroach allergen exposures induced pulmonary eosinophilic inflammation, total and allergen-specific IgE, IgG(1), and IgG(2a) production, and alveolar remodelling. Co-exposures with endotoxin and cockroach allergen significantly increased serum IgE and IgG(1), lung inflammation, and alveolar wall thickness, and decreased airspace volume density. Importantly, compared with exposures with individual substances, the responses to co-exposures were more than additive.

CONCLUSIONS

Repeated inhalation exposures of neonatal and juvenile mice to endotoxin and cockroach allergen increased the pulmonary inflammatory and systemic immune responses in a synergistic manner and enhanced alveolar remodelling in the developing lung. These data underscore the importance of evaluating the effect of multiple, concurrent environmental exposures, and of using an experimental model that incorporates clinically relevant timing and route of exposures.

Real-time PCR quantification of Mycobacterium immunogenum in used metalworking fluids

Rapid detection and quantification of Mycobacterium immunogenum in field samples of metalworking fluids (MWFs) is important for factory fluid surveillance programs. The applicability of the developed DNA extraction and quantitative real-time PCR (qPCR) methods to detect and quantify M. immunogenum in used MWFs was evaluated. Total DNA from these samples was extracted, and M. immunogenum measured by qPCR by comparison with a standard curve derived from plasmid vectors. PCR counts were compared with bacterial culture counts. PCR counts of M. immunogenum varied from 1.42 x 10(3) to 3.68 x 10(6) cells/mL of MWFs. Recovery of M. immunogenum by bacterial culture varied from 2.5% to 70% of qPCR count in corresponding samples. Quantitative PCR could be used to measure M. immunogenum load in MWF samples with greater sensitivity and shorter processing time than the classic bacterial culture-based approach. The proposed qPCR approach could be routinely used in real-time PCR-equipped laboratories to provide early detection of M. immunogenum and to control proliferation that probably leads to hypersensitivity pneumonitis in exposed workers.

Acute effect of glucan-spiked office dust on nasal and pulmonary inflammation in guinea pigs

The acute effects of pure inhaled glucan on respiratory inflammation remain inconclusive and not sufficiently examined with regards to the simultaneous interaction of glucan, endotoxin (lipopolysaccharide, LPS), and house dust in airway inflammation. This study aims at determining effects of simultaneous exposure to office dust and glucan on nasal and pulmonary inflammation. This is relevant for humans with occupational exposure in waste handling and farming and buildings with mold problems. Office dust collected from Danish offices was spiked with 1% (1-3)-beta-glucan (curdlan). Guinea pig nasal cavity volume was measured by acoustic rhinometry (AR) and animals were exposed by inhalation for 4 h to curdlan-spiked dust, unspiked dust, purified air (negative controls), or LPS (positive controls). After exposure (+5 h) or the following day (+18 h), measurements were repeated by AR and followed by bronchoalveolar lavage (BAL). Total and differential cell counts, interleukin (IL)-8 in BAL fluid, and change in nasal volume were compared between groups. A 5-10% increase in nasal volume was seen for all groups including clean air except for a significant 5% decrease for spiked-dust inhalation (+18 h). No marked differences were observed in BAL cells or IL-8 except in LPS-exposed controls. The delayed decrease of nasal cavity volume after exposure to glucan spiked dust suggests a slow effect on the upper airways for curdlan and office dust together, though no pulmonary response or direct signs of inflammation were observed. Glucan-spiked office dust exposures produced a delayed nasal subacute congestion in guinea pigs compared to office dust alone, but extrapolated to nasal congestion in humans, paralleling the nasal congestion seen in human volunteers exposed to the same dust, this may not have clinical importance.

Biomonitoring for assessment of organic dust-induced lung inflammation

Inhalation exposure to particulate matter containing endotoxin (or lipopolysaccharide (LPS)) occurs in a variety of occupations. Nasal lavage and induced sputum have been used to evaluate lung inflammation resulting from such exposures. Whole blood assay (WBA) measures cytokine production of leukocytes after ex vivo stimulation with LPS. The present study examined the effectiveness of WBA for evaluating inflammatory responses and susceptibility. C3HeB/FEJ mice were tolerised by LPS injection or sham tolerised with saline. Animals then inhaled either swine barn dust extract containing endotoxin or saline. Bronchoalveolar lavage (BAL) fluid was assayed for leukocyte counts and pro-inflammatory cytokines (interleukin-6, tumour necrosis factor-alpha). Whole blood was stimulated with 10 or 100 ng.mL(-1) of LPS, incubated for 5 or 18 h and assayed for cytokines. Barn dust-exposed groups revealed significantly higher total cells, neutrophils and cytokines in BAL compared with saline-exposed groups. Animals tolerised to LPS and exposed to barn dust demonstrated lower cellular and cytokine BAL responses. Similarly, WBA yielded significantly elevated cytokines with barn dust exposure and reduced responses with tolerisation. This study demonstrates the efficacy of whole blood assay as a biomarker of inhalation exposure to inflammatory agents and its use for assessing susceptibility to organic dust-induced lung inflammation.

Educational intervention to control cockroach allergen exposure in the homes of hispanic children in Los Angeles: results of the La Casa study

BACKGROUND

Cockroach allergy is common among inner city children with asthma, and exposure to cockroach allergen is associated with more severe disease. However, there has been little evaluation of educational approaches for controlling cockroach infestations and reducing allergen exposure.

OBJECTIVE

An educational intervention to reduce cockroach allergen exposure in the homes of Hispanic children in Los Angeles was implemented and evaluated.

METHODS

Caretakers of 150 children with asthma were randomly assigned to an in-home intervention or comparison group. In the intervention group, peer health educators trained the caretaker to control cockroaches by reducing harbourage and access to food and by applying boric acid, and to reduce allergen exposure by cleaning. Allergen impermeable covers were placed on the child's mattress and pillows. Knowledge, reported and observed behaviour, cockroach counts, and cockroach allergen (Bla g 1) in dust samples from the kitchen and the child's bedding were assessed at study entry and at follow-up 4 months later.

RESULTS

There was improvement in knowledge and in observed and reported behaviour hypothesized to be associated with cockroach control. The geometric mean cockroach number in the intervention homes at the follow-up visit was 60% lower than in the non-intervention homes (95% confidence interval (CI) 14%, 81%). Geometric mean total cockroach allergen collected from the child's bedding was 64% lower in the intervention group (95% CI 12%, 85%). In homes with heavier initial cockroach infestation, there was a larger reduction in total kitchen dust allergen and concentration associated with the intervention than in homes with fewer initial cockroaches.

CONCLUSIONS

We conclude that reduction in number of cockroaches and in total allergen in bedding dust can be achieved by caretakers of asthmatic children following a single home educational intervention by peer educators.

Indoor environmental quality in six commercial office buildings in the midwest United States

The aims of this study were to characterize physical, mechanical, and environmental factors influencing indoor environmental quality (IEQ) in commercial office buildings; document occupant perceptions and psychosocial attributes; and evaluate relationships among these parameters. Six large office buildings in metropolitan areas were selected in Iowa, Minnesota, and Nebraska. Comprehensive sampling was conducted over one week in each building, during all four seasons. This paper presents the study methods and selected results from the first round of sampling (November 1996 to April 1997). Air flow and recirculation rates were quite variable, with the proportion of outdoor air provided to occupants ranging from 10 to 79 CFM/person. Carbon dioxide, carbon monoxide, and temperature were within ranges anticipated for nonproblem buildings. Relative humidity was low, ranging from 11.7 to 24.0 percent. Indoor geometric mean concentrations of total volatile organic compounds (TVOCs) ranged from 73 to 235 microg/m3. The most prevalent compounds included xylene, toluene, 2-propanol, limonene, and heptane. Geometric mean formaldehyde concentrations ranged from 1.7 to 13.3 microg/m3, and mean acetaldehyde levels ranged from <3.0 to 7.5 microg/m3. Airborne concentrations of culturable bacteria and fungi were low, with no samples exceeding 150 CFU/m3. Total (direct count) bioaerosols were more variable, ranging from 5010 to 10,700 organisms/m3. Geometric mean endotoxin concentrations ranged from 0.5 to 3.0 EU/m3. Respirable particulates (PM10) were low (14 to 36 microg/m3). Noise levels ranged from 48 to 56 dBA, with mean light values ranging from 200 to 420 lux. Environmental parameters were significantly correlated with each other. The prevalence of upper respiratory symptoms (dry eyes, runny nose), central nervous system symptoms (headache, irritability), and musculoskeletal symptoms (pain/stiffness in shoulders/neck) were elevated compared to other studies using similar questionnaires. Importantly, psychosocial factors were significantly related to increased symptoms in females, while environmental factors were more closely correlated with symptoms in males. Endotoxin concentrations were associated with symptoms in both males and females. These data will help to identify and quantify the relative role of factors that contribute to sick building syndrome. The data collected in this study may also be used to evaluate the effectiveness of current building operation practices, and can be used to prioritize allocations of resources for reduction of risk associated with IEQ complaints.

Comparison of endotoxin exposure assessment by bioaerosol impinger and filter-sampling methods

Environmental assessment data collected in two prior occupational hygiene studies of swine barns and sawmills allowed the comparison of concurrent, triplicate, side-by-side endotoxin measurements using air sampling filters and bioaerosol impingers. Endotoxin concentrations in impinger solutions and filter eluates were assayed using the Limulus amebocyte lysate assay. In sawmills, impinger sampling yielded significantly higher endotoxin concentration measurements and lower variances than filter sampling with IOM inhalable dust samplers. Analysis of variance for repeated measures showed that this association remained after controlling for other factors such as replicate, sawmill, sawmill operation, wood type, and interaction terms. Endotoxin concentrations in the swine barns were 10-fold higher on average than in sawmills. These samples demonstrated comparable endotoxin concentration estimates for impinger and filter methods although the variability was lower using the impinger method. In both occupational settings, side-by-side replicates were more uniform for the impinger samples than for the filter samples. This study demonstrates that impinger sampling is an acceptable method for quantitation of area endotoxin concentrations. Further, when sampling is performed with impingers for airborne microorganism quantitation, these same impinger solutions can yield valid endotoxin exposure estimates, negating the need for additional filter sampling.

Endotoxin responsiveness and subchronic grain dust-induced airway disease

Endotoxin is one of the principal components of grain dust that causes acute reversible airflow obstruction and airway inflammation. To determine whether endotoxin responsiveness influences the development of chronic grain dust-induced airway disease, physiological and airway inflammation remodeling parameters were evaluated after an 8-wk exposure to corn dust extract (CDE) and again after a 4-wk recovery period in a strain of mice sensitive to (C3H/HeBFeJ) and one resistant to (C3H/HeJ) endotoxin. After the CDE exposure, both strains of mice had equal airway hyperreactivity to a methacholine challenge; however, airway hyperreactivity persisted only in the C3H/HeBFeJ mice after the recovery period. Only the C3H/HeBFeJ mice showed significant inflammation of the lower airway after the 8-wk exposure to CDE. After the recovery period, this inflammatory response completely resolved. Lung stereological measurements indicate that an 8-wk exposure to CDE resulted in persistent expansion of the airway submucosal cross-sectional area only in the C3H/HeBFeJ mice. Collagen type III and an influx of cells into the subepithelial area participated in the expansion of the submucosa. Our findings demonstrate that subchronic inhalation of grain dust extract results in the development of chronic airway disease only in mice sensitive to endotoxin but not in mice that are genetically hyporesponsive to endotoxin, suggesting that endotoxin is important in the development of chronic airway disease.

Inhalation toxicology models of endotoxin- and bioaerosol-induced inflammation

Inhalation toxicology studies in rodents have proven their usefulness for furthering our understanding of the causal agents, mechanisms, and pathology associated with exposures to environmental endotoxins and bioaerosols. Inhalation animal models are used to determine which components of a mixture are the most important toxicants for inducing the observed adverse outcome. They are used to obtain exposure-response relationships for allergens and pro-inflammatory agents to help elucidate disease mechanisms and contribute quantitative data to the risk assessment process. Inhalation models serve as important adjuncts to epidemiology studies and human exposure studies. They are also useful for establishing phenotype in studies of genetic polymorphisms and disease susceptibility and are widely applied for evaluation of safety and efficacy for potential therapeutic agents. In order to produce reliable data, rigorous exposure chamber design, aerosol generation systems, exposure quantitation and experimental protocols must be utilized.

Assessment of particulates and bioaerosols in eastern Canadian sawmills

The purpose of this study was to quantify and identify the airborne contamination in eastern Canadian sawmills. Seventeen sawmills were chosen to cover a wide range of size, geographic distribution, and wood species processed. Within each sawmill different work sites (debarking, sawing, sorting, or planing) were studied separately. Area sampling was performed for exposure assessment. Microbial contaminants were assessed with all-glass impingers 30 and six-stage Andersen microbial samplers; appropriate selective media and culture conditions for bacteria, thermophilic actinomycetes, molds, and yeasts were used. Inhalable dust, endotoxins, temperature, and humidity also were measured. Penicillium species were the most predominant molds with up to 40 different Penicillium species identified. Debarking was the working site most highly contaminated by molds, bacteria, and endotoxins (p=0.0001). At this working site mold levels reached a maximum of 1.5 x 10(6) CFU/m3, whereas the median values for culturable bacteria and endotoxin were 21,620 CFU/m3 and 1,081 endotoxin units/m3, respectively. Planing sites were the most highly dust contaminated (median: 3.0 mg/m3) (p <0.05). Sawmills of eastern Canada contain airborne biological contaminants that vary between working sites, and their microflora is different from that previously described in European sawmills.

Increased levels of markers of microbial exposure in homes with indoor storage of organic household waste

As part of environmental management policies in Europe, separate collection of organic household waste and nonorganic household waste has become increasingly common. As waste is often stored indoors, this policy might increase microbial exposure in the home environment. In this study we evaluated the association between indoor storage of organic waste and levels of microbial agents in house dust. The levels of bacterial endotoxins, mold beta(1-->3)-glucans, and fungal extracellular polysaccharides (EPS) of Aspergillus and Penicillium species were determined in house dust extracts as markers of microbial exposure. House dust samples were collected in 99 homes in The Netherlands selected on the basis of whether separated organic waste was present in the house. In homes in which separated organic waste was stored indoors for 1 week or more the levels of endotoxin, EPS, and glucan were 3.2-, 7.6-, and 4. 6-fold higher, respectively (all P < 0.05), on both living room and kitchen floors than the levels in homes in which only nonorganic residual waste was stored indoors. Increased levels of endotoxin and EPS were observed, 2.6- and 2.1-fold (P < 0.1), respectively, when separated organic waste was stored indoors for 1 week or less, whereas storage of nonseparated waste indoors had no effect on microbial agent levels (P > 0.2). The presence of textile floor covering was another major determinant of microbial levels (P < 0.05). Our results indicate that increased microbial contaminant levels in homes are associated with indoor storage of separated organic waste. These increased levels might increase the risk of bioaerosol-related respiratory symptoms in susceptible people.

Preliminary report on the results of the second phase of a round- robin endotoxin assay study using cotton dust

In an on-going endotoxin assay study, a two-part interlaboratory endotoxin assay study has been completed. The purpose of the study was to compare the variation in assay results between different laboratories, and, if the variation was high, to see if a common protocol would reduce the variation. In both parts of the study, membrane filters laden with the same approximate amount and type of cotton dust were sent for analysis to laboratories that "routinely" perform endotoxin analyses. First, each of these laboratories performed the analysis using the methodology common to its laboratory. In the second part of the study, membrane filters with cotton dust were again sent to the same laboratories where the analyses were performed as before but with a common extraction protocol. The preliminary results from the first phase of the study have been collected and showed that intra-laboratory variations were small, but large and significant interlaboratory variation was observed. The results were reported elsewhere. The preliminary results from the second part of the study consisting of the data currently collected are presented here. Again, intra-laboratory variations were small, but, also again, large and significant inter-laboratory variation was observed. However, in this part of the study, the range between the highest and lowest average results was narrower than in the first part of the study. Influence of the assay kit type was examined. The variation within assay kit type was small but significant differences in results were observed between assay kit types. The findings suggest that endotoxin concentration in samples can be ranked within laboratories, but not necessarily between laboratories. However, some of the variation between laboratories has been reduced by a common extraction protocol which suggests the possibility of further standardization that may lead to better comparability between laboratories.

Ehrlichia chaffeensis antibodies in white-tailed deer, Iowa, 1994 and 1996

Surveillance of 2,277 white-tailed deer for antibodies against Ehrlichia chaffeensis in Iowa showed seropositivity rates of 12.5% in 1994 and 13.9% in 1996. From 1994 to 1996, the estimated number of seropositive deer increased to 54,701 (28%). The increasing deer population and expanding tick distribution may increase risk for human monocytic ehrlichiosis.

Initial results, reliability, and validity of a mental health survey of Mount Pinatubo disaster victims

This report presents the initial results of a mental health survey of 351 tribal and non-tribal Mount Pinatubo disaster victims 6 years after they were displaced following the volcanic eruption in the Philippines on June 12, 1991. Mental illness prevalence rates in both Filipino ethnic groups were comparable to those found in a U.S. study using the same assessment instrument. Post-traumatic stress disorder (PTSD; 27.6%) and major depression (14.0%) were the two most frequent diagnoses. Diagnostic test-retest interviewer agreement was good for probable alcohol abuse (kappa = .65, agreement = 97%) and any mood disorder (kappa = .53, agreement = 91%) but was reduced for any anxiety disorder (kappa = .15, agreement = 81%) and separately evaluated PTSD (kappa = .18, agreement = 69%). Diagnostic test-retest agreement was good among typical Filipinos (mean kappa = .66, mean agreement = 93%) but was reduced among tribal aborigines (mean = .30, mean agreement = 86%). Internal consistency of the PTSD rating scale was high within and across both ethnic groups, including total scale (alpha = .91) and DSM-IV Criteria B, C, and D sub-scales (alpha = .80, 81, and .78, respectively). With the exception of probable alcohol abuse, construct and criterion validity was demonstrated among both tribal and non-tribal Filipinos for all classes of psychiatric disorders by comparing diagnostic results with respondents' views of their physical and mental health and level of functional impairment. Overall, DSM-IV mood, anxiety, alcohol use, and PTSDs with adequate reliability and construct and criterion validity were made in this culturally diverse, non-Western, disaster victim population. However, test-retest diagnostic agreement was reduced for anxiety disorders and among aboriginal respondents, and validity was not demonstrated for probable alcohol abuse.

Worker exposures to particulates, endotoxins, and bioaerosols in two refuse-derived fuel plants

Exposures of refuse-derived fuel (RDF) production workers to total particulates, endotoxin, and total (viable plus nonviable) bioaerosols were characterized at two RDF production plants. Full-shift personal air monitoring for 35 workers was conducted for total particulates, analyzed by gravimetric analysis; endotoxin, analyzed by chromogenic endpoint assay; and total bioaerosols, analyzed by fluorescent microscopy (FM). Geometric mean values of personal air samples were 0.50 mg/m3 for total dust, 29.0 EU/m3 (2.9 ng/m3) for endotoxin, and 6.8 x 10(5) organisms/m3 for bioaerosols. Significant differences were observed between the two plants only for total endotoxin exposures. The mean concentrations for total particulates, total FM bioaerosols, and endotoxins did not differ among the day, evening, or night shifts. Interjob differences were found for exposures to total dust, total endotoxin, and FM bioaerosols. Individual comparisons for total particulates and endotoxin exposures were significant for comparisons between job categories as a result of the greater exposures for personnel cleaning the plants. Significant correlations were detected between total particulates and total endotoxin measurements and between inhalable and total particulates.

Respiratory, gastrointestinal, and other health effects among workers in two refuse-derived fuel plants

This study was conducted to investigate health effects in workers at two refuse-derived fuel processing plants. Cross-shift pulmonary function testing and self reporting of symptoms from questionnaires formed the basis of a cross-sectional epidemiological study. Other topics addressed were exploration of the possibility of a hand to mouth component resulting in diarrhoea observed historically by the microbiological testing of skin. Symptoms of sinus trouble, headaches, nose irritation, and diarrhoea were reported by over 50% of the employees. Small, but statistically significant, cross-shift decrements of 1.50% and 2.01% were noted for forced vital capacity (FVC) and forced expiratory volume in one second (FEV1), respectively. Workers employed seven years or more had significantly larger cross-shift decrements in FVC and FEV1 than those employed for a shorter period. No active cases of diarrhoea were observed. Low lung function decrements characterise the observed workforce. Elevated reporting of some symptoms and a cross-shift decrement that increases with length of employment indicate that further study is warranted.

Efficient killing of inhaled bacteria in DeltaF508 mice: role of airway surface liquid composition

Cystic fibrosis mice have been generated by gene targeting but show little lung disease without repeated exposure to bacteria. We asked if murine mucosal defenses and airway surface liquid (ASL) Cl(-) were altered by the DeltaF508 cystic fibrosis transmembrane conductance regulator mutation. Naive DeltaF508 -/- and +/- mice showed no pulmonary inflammation and after inhaled Pseudomonas aeruginosa had similar inflammatory responses and bacterial clearance rates. We therefore investigated components of the innate immune system. Bronchoalveolar lavage fluid from mice killed Escherichia coli, and the microbicidal activity was inhibited by NaCl. Because beta-defensins are salt-sensitive epithelial products, we looked for pulmonary beta-defensin expression. A mouse homolog of human beta-defensin-1 (termed "MBD-1") was identified; the mRNA was expressed in the lung. Using a radiotracer technique, ASL volume and Cl(-) concentration ([Cl(-)]) were measured in cultured tracheal epithelia from normal and DeltaF508 -/- mice. The estimated ASL volume was similar for both groups. There were no differences in ASL [Cl(-)] in DeltaF508 -/- and normal mice (13.8 +/- 2.6 vs. 17.8 +/- 5.6 meq/l). Because ASL [Cl(-)] is low in normal and mutant mice, salt-sensitive antimicrobial factors, including MBD-1, may be normally active.

Early-onset inflammatory responses in vivo to adenoviral vectors in the presence or absence of lipopolysaccharide-induced inflammation

Adenoviral vectors (Ad) have potential for use in pulmonary gene transfer for treating cystic fibrosis (CF). However, Ad may induce inflammation even in the absence of gene expression. Endotoxin from gram-negative bacteria in the airways of CF patients may also induce inflammation, and may further inhibit vector delivery and gene transfer. We used a mouse model to study the time course of Ad-induced lung inflammation and to assess additivity with lipopolysaccharide (LPS)-induced inflammatory responses. C3H/HeJ endotoxin-resistant (RES) mice hyporesponsive to inflammatory stimuli and normoresponsive C3HeB/FeJ endotoxin-sensitive (SEN) mice were studied to characterize inflammatory responses that follow intratracheal instillation of inactivated Ad, with or without simultaneous inhalation exposure to LPS. Instillation of 10(10) Ad particles dramatically increased bronchoalveolar lavage fluid (BALF) concentrations of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 at 3 to 6 h and induced profound neutrophilia, maximal at 12 to 24 h. SEN mice had tenfold greater responses than did RES mice at 6, 12, and 24 h. Mice exposed to Ad alone, LPS alone, or Ad + LPS had significant inflammation at the 3-h time point as demonstrated by BALF neutrophils, TNF-alpha, and IL-6. With all three treatments, SEN mice had a five- to 300-fold greater response than did RES mice. Importantly, Ad + LPS yielded no greater inflammatory response than LPS without Ad. These data demonstrate that replication-deficient Ad induce early inflammation and LPS-induced inflammation is not augmented by concurrent treatment with Ad.

Organic dust exposures from work in dairy barns

Environmental surveys were conducted in 85 barns, predominantly dairy, in central Wisconsin to characterize exposures to organic dusts and dust constituents from routine barn work. Environmental analytes included airborne dusts (total, inhalable inlet, and respirable), particle size distributions, endotoxins, total spore and bacteria counts, viable bacteria and fungi, histamine, cow urine antigen, mite antigen, ammonia, carbon dioxide, and hydrogen sulfide. The geometric mean (GM) concentration of airborne dusts include area total, 0.74 mg/m3; personal inhalable inlet, 1.78 mg/m3, and area respirable, 0.07 mg/m3. Viable bacteria and fungi, spores, endotoxins, histamine, cow urine antigen, and mite antigen were quantifiable constituents of these organic dusts and potential respiratory exposure hazards from routine dairy barn work. Endotoxin concentrations from the inhalable inlet samples ranged from 25.4 endotoxin units per cubic meter of air (EU/m3) to 34,800 EU/m3. The GM endotoxin concentration from these samples, 647 EU/m3, exceeds estimated threshold exposure levels for respiratory health effects. Ammonia was a common irritant quantified in most dairy barns. There were significant correlations between the concentrations of organic dusts and certain dust constituents, although in most instances these correlations were not strong. These sampling results demonstrate the complex nature of organic dusts and provide quantitative description of the exposures to toxic and immunogenic dust constituents during routine barn work.

Modulation of airway inflammation by CpG oligodeoxynucleotides in a murine model of asthma

Asthma has been increasing in industrialized countries. Evidence suggests that asthma is caused by a Th2 immune response to inhaled environmental Ags and that childhood infections protect against this. We have shown that bacterial DNA contains motifs, centered on unmethylated CpG dinucleotides, which induce Th1-type responses. We hypothesized that the Th1 effect of these CpG motifs may oppose the Th2 type allergic response and suggest that this may account for the protective effect of childhood infection against asthma. We examined the effects of CpG-motif oligodeoxynucleotides (CpG ODN) in a murine model of asthma. Airway eosinophilia, Th2 cytokine induction, IgE production, and bronchial hyperreactivity were prevented by coadministration of CpG ODN with the Ag. Significantly, in a previously sensitized mouse, CpG ODN can prevent allergen-induced airway inflammation. These studies suggest that exposure to CpG DNA may protect against asthma.

Prospective epidemiologic evaluation of laboratory animal allergy among university employees

OBJECTIVES

Evaluation of incidence and risk factors for development of laboratory animal allergy (LAA) among new hires previously unexposed to lab animals.

METHODS

Baseline, 6-month and yearly follow-up, questionnaires, pulmonary functions, and methacholine challenges were collected from 98 never-before occupationally exposed and 90 control laboratory researchers. The two groups were followed between 6 and 36 months.

RESULTS

At baseline, there were no differences in atopy, pulmonary functions, or methacholine reactivity between the two groups. The incidence of work-related asthma was comparable in the two groups, approximately 2.5% at 6 months and 4.5% at 24 months. The rate of decline in FEV1 was statistically significantly greater in the animal-exposed than nonanimal-exposed workers, and animal-exposed smokers' FEV1 declined significantly more rapidly than any other groups'.

CONCLUSION

Despite the low incidence of laboratory-animal allergy and work-related asthma in this group, this study corroborates previously described interaction between smoking and animal exposure.

Field evaluation of endotoxin air sampling assay methods

This study tested the importance of filter media, extraction and assay protocol, and bioaerosol source on the determination of endotoxin under field conditions in swine and poultry confinement buildings. Multiple simultaneous air samples were collected using glass fiber (GF) and polycarbonate (PC) filters, and these were assayed using two methods in two separate laboratories: an endpoint chromogenic Limulus amebocyte lysate (LAL) assay (QCL) performed in water and a kinetic chromogenic LAL assay (KQCL) performed in buffer with resistant-parallel line estimation analysis (KLARE). In addition, two aqueous filter extraction methods were compared in the QCL assay: 120 min extraction at 22 degrees C with vigorous shaking and 30 min extraction at 68 degrees C with gentle rocking. These extraction methods yielded endotoxin activities that were not significantly different and were very highly correlated. Reproducibility of endotoxin determinations from duplicate air sampling filters was very high (Cronbach alpha all > 0.94). When analyzed by the QCL method GF filters yielded significantly higher endotoxin activity than PC filters. QCL and KLARE methods gave similar estimates for endotoxin activity from PC filters; however, GF filters analyzed by the QCL method yielded significantly higher endotoxin activity estimates, suggesting enhancement of the QCL assay or inhibition of the KLARE asay with GF filters. Correlation between QCL-GF and QCL-PC was high (r = 0.98) while that between KLARE-GF and KLARE-PC was moderate (r = 0.68). Analysis of variance demonstrated that assay methodology, filter-type, barn-type, and interactions between assay and filter-type and between assay and barn-type were important factors influencing endotoxin exposure assessment.

CpG motifs in bacterial DNA cause inflammation in the lower respiratory tract

Since unmethylated CpG motifs are more frequent in DNA from bacteria than vertebrates, and the unmethylated CpG motif has recently been reported to have stimulatory effects on lymphocytes, we speculated that bacterial DNA may induce inflammation in the lower respiratory tract through its content of unmethylated CpG motifs. To determine the role of bacterial DNA in lower airway inflammation, we intratracheally instilled prokaryotic and eukaryotic DNA in C3H/HeBFEJ mice and performed whole lung lavage 4 h after the exposure. Heat denatured, single stranded Escherichia coli genomic DNA (0.06 ng endotoxin/microg DNA) was compared to heat denatured, single stranded calf thymus DNA (0.007 endotoxin/microg DNA). 10 microg of bacterial DNA, in comparison to 10 microg of calf thymus DNA, resulted in a fourfold increase in the concentration of cells (P = 0.0002), a fivefold increase in the concentration of neutrophils (P = 0.0002), a 50-fold increase in the concentration of TNF-alpha (P = 0.001), and a fourfold increase in the concentration of both IL-6 (P = 0.0003) and macrophage inflammatory protein-2 (P = 0.0001) in the lavage fluid. Importantly, instillation of 0.60 ng of E. coli LPS resulted in a negligible inflammatory response. To test whether the stimulatory effects of bacterial DNA are due to its unmethylated CpG dinucleotides, we methylated the bacterial DNA and also prepared 20 base pair oligonucleotides with and without CpG motifs. In comparison to instillation of untreated bacterial DNA, methylation of the bacterial DNA resulted in a significant reduction in the concentration of cells and cytokines in the lower respiratory tract. Moreover, oligonucleotides containing embedded unmethylated CpG motifs resulted in inflammation in the lower respiratory tract that was indistinguishable from that observed with untreated bacterial DNA. In contrast, oligonucleotides without the embedded CpG motifs or with embedded but methylated CpG motifs resulted in significantly less inflammation in the lower respiratory tract. The possible relevance of these data to human disease was shown by extracting and analyzing DNA in sputum from patients with cystic fibrosis (CF). Approximately 0.1 to 1% of this sputum DNA was bacterial. Intratracheal instillation of highly purified CF sputum DNA caused acute inflammation similar to that induced by bacterial DNA. These findings suggest that bacterial DNA, and unmethylated CpG motifs in particular, may play an important pathogenic role in inflammatory lung disease.

Laboratory comparison of vacuum, OSHA, and HUD sampling methods for lead in household dust

The goals of this project were to evaluate and compare the efficiency and reproducibility of three methods for sampling lead-containing dust in homes. Lead-containing dust was generated in a 1-m3 chamber and uniformly deposited onto surfaces typically found in the home (painted wood, unpainted wood, varnished wood, linoleum, and carpet). Trials with three levels of lead concentrations were performed for each surface. Replicate, side-by-side, surface samples were collected using the Occupational Safety and Health Administration (OSHA) wipe method, the Department of Housing and Urban Development (HUD) wipe method, and a vacuum-filter method. Samples were digested with nitric acid and analyzed using graphite furnace atomic absorption spectroscopy per National Institute of Occupational Safety and Health Method 7105. Recovery for the HUD method was consistently the highest on most surfaces (linoleum, 89.9 to 108.9%; painted wood, 71.2 to 153.7%; unpainted wood, 25.3 to 76.0%; varnished wood, 8.7 to 165.6%). On carpet the vacuum method had a significantly higher recovery (26.2 to 47.8%). For all sampling methods the percent recovery depended on type of surface and lead concentration. The reproducibility of percent recovery for the HUD (pooled coefficient of variation [CV] = 0.22) and OSHA (pooled CV = 0.27) methods was lower than that of the vacuum method (pooled CV = 0.46), though not statistically significant. Reproducibility for all methods did not vary significantly over surface type or lead concentration. Overall, the HUD method yielded the most accurate measurements, with recoveries closest to 100%. It was also more durable than the OSHA method, where Whatman filters were observed to tear.

Respiratory symptoms and lung function abnormalities among machine operators in automobile production

This cross-sectional study was designed to assess differences in prevalence of respiratory symptoms and lung function between machine operators exposed to semisynthetic or soluble metal-working fluids (MWFs) and unexposed assemblers and to assess exposure-response relationships with MWF type, total aerosol, endotoxin, culturable bacteria and fungi. We evaluated 183 machine operators and 66 assemblers from one large automobile transmission plant using questionnaires, spirometry data, and cross-shift assessment of both lung function and respiratory symptoms. We found that airborne exposures to total aerosol, endotoxin, culturable bacteria and fungi were higher in machine operations than in the assembly area. There was a correlation between bulk and airborne culturable bacteria, but not between bulk and airborne culturable fungi. Machine operators had significantly more usual cough, usual phlegm, work-related chest tightness and post-shift symptoms of chest tightness, throat irritation, and cough compared with assemblers. We found exposure-response relationships between respiratory symptoms and total aerosol, as well as culturable fungi and bacteria. Associations with endotoxin were not strong or consistent, possibly because airborne levels were generally low. Cross-shift lung function decrements did not differ between machine operators and assemblers and there were no associations with MWF or specific exposures. The finding of respiratory symptoms at low levels of exposure in this study suggests the need to re-assess total aerosol thresholds. Associations between airborne fungal exposures and respiratory symptoms need further study to characterize sources of exposure other than MWF in machining operations.

Application of flow cytometry and fluorescent in situ hybridization for assessment of exposures to airborne bacteria

Current limitations in the methodology for enumeration and identification of airborne bacteria compromise the precision and accuracy of bioaerosol exposure assessment. In this study, flow cytometry and fluorescent in situ hybridization (FISH) were evaluated for the assessment of exposures to airborne bacteria. Laboratory-generated two-component bioaerosols in exposures chambers and complex native bioaerosols in swine barns were sampled with two types of liquid impingers (all-glass impinger-30 and May 3-stage impinger). Aliquots of collection media were processed and enumerated by a standard culture technique, microscopy, or flow cytometry after nucleic acid staining with 4',6-diamidino-2-phenylindole (DAPI) and identified taxonomically by FISH. DAPI-labeled impinger samples yielded comparable estimates of bioaerosol concentrations when enumerated by microscopy or flow cytometry. The standard culture method underestimated bioaerosol concentrations by 2 orders of magnitude when compared to microscopy or flow cytometry. In the FISH method, aliquots of collection media were incubated with a probe universally complementary to eubacteria, a probe specific for several Pseudomonas species, and a probe complementary to eubacteria for detection of nonspecific binding. With these probes, FISH allowed quantitative identification of Pseudomonas aeruginosa and Escherichia coli bioaerosols in the exposure chamber without measurable nonspecific binding. Impinger samples from the swine barn demonstrated the efficacy of the FISH method for the identification of eubacteria in a complex organic dust. This work demonstrates the potential of emerging molecular techniques to complement traditional methods of bioaerosol exposure assessment.

The kinetics of grain dust-induced inflammation of the lower respiratory tract

To characterize the kinetics of grain dust-induced airflow obstruction and inflammation in the lower respiratory tract, we performed serial spirometry and bronchoalveolar lavage (BAL) in human subjects and whole-lung lavage in mice following a single inhalation exposure to comparable dosages of corn dust extract (CDE). Following inhalation of CDE, our human study subjects developed significant airflow obstruction 10 min postexposure which persisted for 48 h. Human subjects and mice had similar acute and persistent changes in lavage cellularity after exposure to CDE. A profound increase in the concentration of lavage neutrophils was present in the initial postexposure lavage in both human subjects and mice. This increase persisted for 96 h in human subjects and 48 h in mice. Small but significant increases in lavage macrophage concentration were present 48 h postexposure in human subjects and at 96 h postexposure in mice. Inhalation of CDE resulted in a significant increase in the concentration of proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in the lavage fluid of both human subjects and mice. Similarly, significant increases in lavage concentrations of IL-8 in humans and macrophage inflammatory protein-2 (MIP-2) in mice occurred after inhalation of CDE. The lavage concentration of all measured proinflammatory cytokines returned to baseline levels by 168 h in humans and 96 h in mice. These findings suggest that a single inhalation challenge of CDE results in airflow obstruction and lower respiratory tract inflammation that may last for several days. These physiologic and inflammatory responses appear to be self-limited with no evidence of persistent injury 1 wk after the inhalation challenge. Moreover, the inflammatory response in the lower respiratory tract after inhalation of grain dust is similar in human subjects and mice, suggesting that the mouse may be an appropriate model for further investigation of grain dust-induced inflammation.

Pulmonary effects of machining fluids in guinea pigs and mice

Acute pulmonary effects of inhalation exposure to (unused) neat and in-use metalworking fluids (MWF) were studied to evaluate the potency of characterized MWF in terms of their effects on breathing and lung inflammation. Inhalation exposure of guinea pigs caused dose-dependent changes in respiratory rate and volume that were used to quantify potency. In-use MWF was consistently more toxic than the corresponding neat MWF. Significant predictors of respiratory responses were whether MWF was neat or in-use (p = 0.0001), exposure concentration (p = 0.022), MWF formulation (p = 0.031), and the particular in-use MWF tested (p = 0.032). Inhalation exposures to MWF biocides resulted in dose-dependent sensory irritation responses. Guinea pig studies revealed significant inflammation resulting from MWF exposure marked by change in bronchoalveolar lavage (BAL) fluid from 3% neutrophils (controls) to 60-79% (MWF-exposed) and 25-fold increase in total BAL cells. The in-use MWF ranged in endotoxin concentration from 280 to 1.7 x 10(5) endotoxin units (EU)/mL. To investigate the role of endotoxin, studies were carried out in mice sensitive (SEN) and resistant (RES) to endotoxin. SEN mice revealed a dose-dependent 10,000-fold increase in BAL neutrophils and a 100-fold increased concentration of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) following inhalation exposure to in-use MWF. This inflammatory response was not observed with exposure to neat MWF or with sham exposure. RES mice demonstrated virtually no response to the inhaled MWF for total cells, neutrophils, IL-6, or TNF-alpha. Removal of microorganisms by filtration of the in-use MWF did not change the responses observed in either strain. These studies demonstrate that lung inflammation may be an important outcome from exposure to in-use MWF and that endotoxin is a toxicant of importance.

The utility of preliminary surveys to detect the cause of acute metalworking fluid hazards

This paper describes preliminary studies undertaken to optimize a later epidemiologic study, the aim of which was to identify a causative agent of adverse respiratory effects and dermatitis among production machinists. Two methods were used to rate coolant system hazards. The results of a voluntary plantwide questionnaire with an 18% participation rate showed that both dermatologic and respiratory symptoms were higher among machine operators than among maintenance or assembly workers, that symptoms were not more prevalent early in the week, and that dermatitis may be associated with smoking status; however, the questionnaire was not helpful in rating individual coolant system hazards. The hazard ratings provided by an in-plant expert panel were strongly associated with particular synthetic coolant containing an ethoxylated phenol; however, the resulting design for a later epidemiologic study could not be implemented due to changes in coolants used at the plant.

Dermatitis among automobile production machine operators exposed to metal-working fluids

This cross-sectional study was designed to assess differences in prevalence of contact dermatitis between machine operators exposed to metal-working fluids (MWFs) and unexposed assemblers, and to assess potential risk factors for contact dermatitis among these machine operators. In their work, machine operators were exposed to either semisynthetic or soluble oil MWFs. We evaluated 158 machine operators and 51 assemblers from one large automobile transmission plant using questionnaires, dermatologist examination of the skin, and dermal dosimetry to measure wetness and metal exposures. We found that machine operators had more combined (definite plus possible) dermatitis (27.2% vs. 13.7%, chi(2) = 3.9, p = 0.05, 1 df) compared with assemblers. Among machine operators, risk factors significantly associated with (combined) dermatitis were subjective assessment of wetness of the work, exposure to semisynthetic as opposed to soluble oil MWF, current cigarette smoking, and increasing worker age. These risk factors suggested preventive and control measures including control of wet work, surveillance program including early self-report of dermatitis, consideration of replacement of semisynthetic with soluble oil MWFs, and strictly limiting smoking among machine operators exposed to MWFs.

The role of atopy in grain dust-induced airway disease

To determine whether atopy influences the physiologic or inflammatory response to grain dust, we compared spirometric measures of airflow and bronchoalveolar lavage (BAL) measures of lower respiratory tract inflammation between demographically similar nonatopic (n = 10) and atopic (n = 10) study subjects after each of two inhalation exposures: Hanks' balanced salt solution (HBSS) and corn dust extract (CDE; 0.4 microgram of endotoxin/kg body weight). Subjects were healthy nonsmokers with similar baseline pulmonary function, without bronchial hyperreactivity, and had not participated in agriculture. Atopic subjects had two or more positive skin responses to 10 common environmental allergens. Both groups developed significant airflow obstruction and lower airway inflammation after CDE inhalation. Importantly, the magnitude of the post-CDE exposure airflow decrements, BAL cellularity, and BAL concentration of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), IL-6, and IL-8 did not significantly differ between atopics and nonatopics. The concentrations of histamine and eosinophils in the BAL fluid were unaffected by CDE inhalation and did not significantly differ between atopics and nonatopics. Atopic status does not appear to be a significant determinant of airflow obstruction or lower airway inflammation following CDE inhalation. Our findings suggest that atopy may play, at most, a minor role in the development of grain dust-induced airway disease.

Grain dust and endotoxin inhalation challenges produce similar inflammatory responses in normal subjects

STUDY OBJECTIVE

To compare the physiologic and inflammatory response following inhalation of corn dust extract (CDE) and lipopolysaccharide (LPS) solutions in normal subjects.

DESIGN

Randomized, double-blind crossover design.

PARTICIPANTS

Fourteen healthy, nonatopic, nonasthmatic, never-smoking volunteers.

INTERVENTIONS

On separate visits, subjects underwent a series of four inhalation challenges to LPS or CDE, each containing either a high (6 micrograms/mL) or low (0.9 microgram/mL) endotoxin concentration, and administered at equal Xolumes.

RESULTS

Chest tightness, cough, dyspnea, and sputum production were experienced following both LPS and CDE exposures and with similar frequency at both high and low endotoxin concentrations. LPS and CDE inhalations caused acute declines in FEV1, and the changes in FEV1 from baseline following exposure to both inhalants were not significantly different at both high and low endotoxin concentrations. Following exposure to the high-endotoxin LPS and CDE, no consistent differences in total cell and cytokine (tumor necrosis factor-alpha [TNF-alpha], interleukin-1 beta [IL-1 beta], IL-6, IL-8) concentrations were seen between exposures, although the neutrophil concentration was greater following the LPS exposure (p = 0.01). BAL cellularity and cytokine concentrations following the low-endotoxin LPS and CDE exposure revealed no differences, except for IL-1 beta, which was greater following LPS exposure (p = 0.05). The high-endotoxin LPS and CDE exposures resulted in greater increases in BAL neutrophils and cytokines in comparison to its respective low-endotoxin exposure.

CONCLUSIONS

At exposure levels of endotoxin, LPS and CDE result in similar symptoms, changes in airflow, and increases in BAL inflammatory cells and mediators. Moreover, the physiologic and inflammatory response to LPS and CDE appears to be related to the exposure level of endotoxin.

Role of endotoxin in grain dust-induced lung inflammation in mice

To investigate the role of endotoxin in grain dust-induced airway inflammation, we reduced the endotoxin activity from extracts of corn dust (CDE), using three distinct methods, and determined the effect of endotoxin activity on the in vitro and in vivo inflammatory response to CDE. Escherichia coli lipopolysaccharide solution (LPS) and CDE solution were separated into > 100-kDa and < 100-kDa fractions by ultracentrifugation. Endotoxin activity was predominantly present in the > 100-kDa fractions of the LPS and CDE solutions. Charged-membrane filtration of the > 100-kDa fractions of LPS and CDE resulted in the reduction of endotoxin activity by 99.9 and 80%, respectively. Treatment of the > 100-kDa fractions of LPS and CDE with polymyxin B-coated beads reduced the endotoxin activity by 96 and 89%, respectively. The untreated > 100-kDa fractions of LPS and CDE caused significantly greater (P < 0.01) release of tumor necrosis factor-alpha (TNF-alpha) from THP-1 cells in vitro compared with its respective < 100-kDa fraction or either of the treated (charged filter or polymyxin B) > 100-kDa fractions. Similarly, mice exposed to either of the untreated > 100-kDa fractions of LPS or CDE by inhalation developed significantly greater (P < 0.01) concentrations of lavage neutrophils and TNF-alpha in the lavage fluid compared with mice exposed to the respective < 100-kDa fraction or either of the treated > 100-kDa fractions. These results indicate that endotoxin is primarily responsible for the in vitro and in vivo inflammatory response to CDE.

Nasal lavage cellularity, grain dust, and airflow obstruction

To evaluate the clinical utility of nasal lavage (NL), we performed post-work shift NL on 172 grain workers and 78 postal worker control subjects. The grain worker group included a higher percentage of current smokers (25.7% vs 16.7%) and a lower percentage of former smokers (21.15% vs 35.9%) compared with the postal workers. The control subjects included more female workers and were slightly older than the grain workers. Compared with the postal workers, the grain workers were exposed to significantly greater concentrations of total dust (0.1 +/- 0.0 vs 6.8 +/- 1.4 mg/m3; mean +/- SEM) and total endotoxin (4.3 +/- 0.8 vs 2,372.4 +/- 653.8 endotoxin units/m3). NL from gain workers showed a higher concentration of total cells (55,000 +/- 14,000 vs 25,000 +/- 5,000 cells per milliliter; p=0.03), a higher concentration of squamous epithelial cells (17,029.0 +/- 4,177 .0 vs 7,103.7 +/- 1,479.8 cells per milliliter; p=0.03), and a higher concentration of neutrophils (40,058.0 +/- 12,803.2 vs 17,891.0 +/- 3,822.3 cells per milliliter; p=0.10) compared with postal workers. Importantly, these differences in NL cellularity between grain workers and postal workers were observed within the three strata of smokers. To further assess the importance of total cells, squamous epithelial cells, and neutrophils in the NL fluid of grain workers, we investigated the relationship between these cell concentrations and (1) measures of dust and endotoxin exposure during the work shift. (2) spirometric measures of airflow obtained immediately before the NL, and (3) work-related respiratory symptoms. The concentration of total cells, the concentration of squamous epithelial cells, or the concentration of neutrophils in the NL was not associated with ambient levels of dust or endotoxin, with baseline or cross-shift changes in lung function, or with work-related respiratory symptoms. These findings suggest that increased NL cellularity may be seen in workers exposed to high dust levels. However, the NL cellularity does not appear to be associated with ambient concentrations of dusts or endotoxins, with signs of airflow obstruction, or with work-related respiratory symptoms.

Epidemiologic assessment of laboratory animal allergy among university employees

The prevalence of, and risk factors for, laboratory animal allergy (LAA) among university employees were evaluated in a cross-sectional university-based study. A stratified random sample was drawn based on current or no laboratory animal exposure and smoking status. Participants received a modified ATS questionnaire; spirometry; methacholine challenge; and intradermal allergen skin tests. One hundred three currently animal-exposed and 113 never-occupationally-exposed employees participated. Controlling for smoking, currently exposed workers were significantly more likely than controls to describe work-related cough, odds ratio (O.R.) = 6.87; wheeze, O.R. = 12.96; and chest tightness, O.R. = 2.89. Skin test reactivity to non-animal antigens was associated in a dose-response fashion with both upper and lower respiratory symptoms, O.R. = 1.45 and 1.65, respectively, for each additional positive skin test. Exposed workers were significantly more likely than controls to react to methacholine at either 10 or 25 mg/ml, while controlling for smoking status, prior allergy, or asthma. Multiple logistic regression analysis revealed history of hay fever, family history of allergy, non-animal skin test positivity, animal bites, age, and smoking status to each be associated with work-related respiratory symptoms. These data suggest that atopy and smoking status are risk factors for LAA symptoms. Smoking was associated with work-related respiratory symptoms among animal-exposed workers, but not with skin test positivity. It is therefore recommended that periodic screening evaluations be performed on laboratory animal workers and that workers who are atopic, are smokers, or are symptomatic be placed in low exposure settings. These data further, support the need for efficient exhaust ventilation, personal protective clothing and, among high risk workers, the use of efficient respiratory protection.

The role of endotoxin in grain dust-induced lung disease

To identify the role of endotoxin in grain dust-induced lung disease, we conducted a population-based, cross-sectional investigation among grain handlers and postal workers. The study subjects were selected by randomly sampling all grain facilities and post offices within 100 miles of Iowa City. Our study population consisted of 410 grain workers and 201 postal workers. Grain workers were found to be exposed to higher concentrations of airborne dust (p = 0.0001) and endotoxin (p = 0.0001) when compared with postal workers. Grain workers had a significantly higher prevalence of work-related (cough, phlegm, wheezing, chest tightness, and dyspnea) and chronic (usual cough or phlegm production) respiratory symptoms than postal workers. Moreover, after controlling for age, gender, and cigarette smoking status, work-related respiratory symptoms were strongly associated with the concentration of endotoxin in the bioaerosol in the work setting. The concentration of total dust in the bioaerosol was marginally related to these respiratory problems. After controlling for age, gender, and cigarette smoking status, grain workers were found to have reduced spirometric measures of airflow (FEV1, FEV1/FVC, and FEF25-75) and enhanced airway reactivity to inhaled histamine when compared with postal workers. Although the total dust concentration in the work environment appeared to have little effect on these measures of airflow obstruction, higher concentrations of endotoxin in the bioaerosol were associated with diminished measures of airflow and enhanced bronchial reactivity. Our results indicate that the concentration of endotoxin in the bioaerosol may be particularly important in the development of grain dust-induced lung disease.

Endotoxin responsiveness and grain dust-induced inflammation in the lower respiratory tract

To identify the role of endotoxin responsiveness in grain dust-induced airway disease, we used two models of extotoxin hyporesponsiveness to perform inhalation exposure studies in mice. In the first model, we investigated whether genetic resistance to endotoxin would alter the inflammatory response to inhaled grain dust by comparing the inflammatory response in the lower respiratory tract of endotoxin-sensitive and -resistant male mice after inhalation of pyrogen-free saline, corn dust extract (CDE), sterile CDE (SCDE), or lipopolysaccharide (LPS). Endotoxin-sensitive and -resistant mice were exposed for 4 h to nebulized solutions of LPS, SCDE, or CDE. Another group of endotoxin-sensitive and -resistant mice was sham exposed for 4 h to nebulized sterile saline. Dose-response relationships for endotoxin were explored for LPS, SCDE, and CDE. Bronchoalveolar lavage (BAL) 5 h after the start of exposure demonstrated a higher concentration of total cells, neutrophils (PMNs), and tumor necrosis factor-alpha (TNF-alpha) in BAL fluid after inhalation of CDE, SCDE, or LPS in endotoxin-sensitive than in endotoxin-resistant mice. Whereas endotoxin-sensitive mice demonstrated a dose-response relationship between the endotoxin concentration in each of the solutions and the concentration of cells, PMNs, and TNF-alpha in BAL fluid, concentrations of TNF-alpha were significantly higher only in BAL fluid of endotoxin-resistant mice exposed to higher concentrations of SCDE or CDE. In the second model, we investigated whether acquired endotoxin tolerance would alter the inflammatory response to SCDE.(ABSTRACT TRUNCATED AT 250 WORDS)

Bioaerosol sampling in field studies: can samples be express mailed?

Bioaerosol sampling for viable microorganisms was conducted in 25 dairy barns in summer and in winter to examine the relationship of sample storage and shipping in determining bioaerosol concentrations separately for yeasts, molds, mesophilic bacteria, and thermophilic organisms. The study also compared the performance of three sampling methods--(1) all-glass impinger (AGI) used with peptone solution in both seasons and (2) betaine solution in winter; and (3) the nuclepore filtration and elution (NFE) method, using air filtration with subsequent elution and culturing--which were studied in a pairwise fashion with duplicate, simultaneous, side-by-side sampling. For each sample, one duplicate was analyzed within two hours in a laboratory less than 50 km from the sampling site, while the other was express-mailed to the authors' laboratory. Concentrations of all microorganisms measured by the AGI peptone method were unaffected by mailing in winter, but mesophilic bacteria increased in summer. AGI betaine samples were unchanged except for increased concentrations of molds after mailing in winter. Yeasts and mesophilic bacteria significantly decreased after mailing of NFE samples. Pairwise comparison of the sampling methods in winter yielded no significant differences in airborne concentrations for the yeasts, mesophilic bacteria, and thermophilic bacteria. Both AGI betaine and NFE methods had significantly greater concentrations of molds than AGI peptone. In summer, concentrations of yeasts and mesophilic bacteria were significantly greater with AGI peptone, as were molds with the NFE method.(ABSTRACT TRUNCATED AT 250 WORDS)

Grain dust-induced airflow obstruction and inflammation of the lower respiratory tract

To investigate the relationship between the physiologic and biologic effects of grain dust inhalation, we exposed 15 nonsmoking, nonasthmatic, nonatopic male grain handlers to buffered saline and aqueous corn dust extract by inhalation challenge in a crossover study. The inhalation challenges to buffered saline and corn dust extract were separated by at least 14 d. Compared with buffered saline, inhalation of corn dust extract resulted in significant airflow obstruction, which was observed within 30 min of exposure and persisted for 5 h. Inhalation of corn dust extract resulted in an acute inflammatory response characterized by higher concentrations of neutrophils (p = 0.001), IL-1 beta (p = 0.001), IL-1RA (p = 0.001), IL-6 (p = 0.001), IL-8 (p = 0.001), and TNF-alpha (p = 0.04) in bronchoalveolar lavage (BAL) fluid. mRNA levels specific for IL-1 beta, IL-1RA, IL-6, and IL-8 from cells present in the BAL fluid were significantly greater after challenge with corn dust extract than after challenge with buffered saline. Importantly, no significant differences were observed in the concentration of lymphocytes or eosinophils in the BAL fluid following inhalation of corn dust extract, and the concentrations of histamine and 15-HETE were similar in BAL fluid after the two challenges. The maximal percentage decrease in FEV1 was significantly associated with the absolute neutrophil concentration in the BAL fluid (p = 0.001), as well as the concentration of TNF-alpha (p = 0.03), IL-1 beta (p = 0.005), IL-1RA (p = 0.001), IL-6 (p = 0.001), and IL-8 (p = 0.001) in the BAL fluid.(ABSTRACT TRUNCATED AT 250 WORDS)

Agents in organic dust: criteria for a causal relationship

Identification of agents of disease causation in organic dust is complicated by the fact that multiple agents may be involved, and these agents may act in a synergistic or additive fashion and cause a number of conditions resulting from chronic toxic or inflammatory effects. A new systematic approach to evaluating available data for evidence of disease-causing agents in organic dust is proposed. It combines, in a matrix fashion, principles of Koch's postulates, River's postulates, principles of epidemiologic determinants, and weight of evidence theory. By applying these principles in a systematic fashion, the strength of the scientific evidence for a specific agent can objectively be evaluated.

Experimental grain dust atmospheres generated by wet and dry aerosolization techniques

Properties of grain dust aerosols generated using wet and dry techniques were studied. Relative to the dry aerosol generation, the wet generation technique yielded a smaller particle size distribution (MMAED of 1.5 microns vs. 15.5 microns) but also reduced the viability of microorganisms. Analysis of dust mass and endotoxin activity on cascade impactor stages demonstrated equivalent partitioning of the airborne endotoxin with the dust mass for aerosols produced by either generation method. Comparison of laboratory-generated atmospheres to field sampling indicated a greater proportion of respirable microorganisms in soybean handling facilities than were generated using the dry aerosol system. Limitations of both aerosol generation systems were found that may affect the validity of inhalation toxicology studies in which these bioaerosols are artificially created.

The effects of inhalation of grain dust extract and endotoxin on upper and lower airways

To characterize the short-term effects of grain dusts on pulmonary function, mucosal inflammation, and systemic responses, four women and three men inhaled nebulized corn and soybean dust extracts, endotoxin diluted with Hanks' balanced salt solution (HBSS), and HBSS. Subjects were volunteers recruited via newspaper advertisement and were required to be healthy, nonasthmatic, nonatopic never-smokers. The mean age was 26.9 years (range, 19 to 36 years). Using a randomized, double-blind, crossover design, each subject was challenged with each of the 4 substances with at least 10 days between challenges. Serial spirometry, peripheral blood leukocyte and differential cell counts, and 24-h postchallenge nasal lavages were performed. Extracts were produced by mixing 3 g of the corn or soybean dust with 30 ml HBSS followed by shaking for 60 min, centrifugation, then filter sterilization. The endotoxin solution was produced by mixing lyophilized Escherichia coli endotoxin (serotype 0111:B4) with HBSS to attain a final concentration of 7 mg/L, which was the same as the concentration of endotoxin in both grain dust solutions. The pH of all solutions and unmixed HBSS was adjusted to 5.8, which was the native pH of the soybean dust extract. Subjects were challenged with 0.08 ml/kg of each substance, resulting in a range of endotoxin doses of 30 to 60 micrograms, similar to that which a worker might inhale over the course of one workshift. The lowest mean percentage baseline FEV1 (+/- SD) after inhalation challenge was 99.2 +/- 2.1 for HBSS, and it was significantly lower for endotoxin (90.1 +/- 8.5, p = 0.03), corn dust extract (93.1 +/- 4.3, p = 0.02), and soybean dust extract (96.2 +/- 3.7, p = 0.03). In addition, a peripheral blood leukocytosis developed after exposure to all three endotoxin-containing solutions (p < 0.05), yet a lower peripheral blood lymphocyte count was found only after inhalation of corn dust extract (p = 0.02). Interestingly, this was associated with a higher nasal lavage lymphocyte count after inhalation of corn dust extract (p = 0.03). Neither the decrease in peripheral blood lymphocytes nor the increase in nasal lymphocytes were found after inhalation of soybean dust extract or endotoxin. Our results indicate that extracts of grain dusts have physiologic effects similar to endotoxin. However, in spite of the same endotoxin levels, the effects of corn dust extract appear to have different biologic activity than either soybean dust extract or endotoxin.

Sump additives as a source of bioaerosols in a school building

An investigation was launched following complaints of poor air quality and building-related illness in a public elementary school. Occlusion of air intakes put the building under negative pressure and caused vents from a below-ground sump to become air intakes. Outside air drawn through the sump pit traveled into the adjacent main air handling unit and was disseminated throughout the building. Sump additives introduced in an attempt to counteract foul odors contained spores of Bacillus species, which appeared as bioaerosols throughout the school. Viable microbial sampling identified B subtilis, B cereus, and B licheniformis in the sump room and classrooms at levels as high as 760 colony forming units/m3 (CFU/m3). Concentrations of CO2 in classrooms were 1250 ppm, indicating inadequate makeup air. Remediation was accomplished by opening the air intakes, isolating the sump room from the air handling system, venting the sump to the outside, and flushing the sump with fresh water on a regular basis.

Comparison of bioaerosol sampling methods in barns housing swine

The air in livestock buildings contains bioaerosol levels that are sufficiently high to cause adverse health effects in animals and workers. These bioaerosols are complex mixtures of live and dead microorganisms and their products as well as other aeroallergens. The effectiveness of sampling methods used for quantifying the very high concentrations of microorganisms in these environments has not been well studied. To facilitate an accurate assessment of respiratory hazards from viable organisms in agricultural environments, three bioaerosol sampling methods were investigated: the Andersen microbial sampler method (AMS), the all-glass impinger method (AGI), and the Nuclepore filtration-elution method (NFE). These methods were studied in a parallel fashion in 24 swine confinement buildings. Measurements were taken in two seasons with three types of culture media in duplicate to assess total bacteria, gram-negative enteric bacteria, and total fungi. Methods were analyzed for the proportion of samples yielding data within the limits of detection, intraclass reliability, and correlation between methods. For sampling viable bacteria, the AMS had a poor data yield because of overloading and demonstrated weak correlation with the AGI. Conversely, the AGI and NFE gave sufficient numbers of valid data points (90%), yielded high intraclass reliabilities (alpha greater than or equal to 0.92), and were highly correlated with each other (r = 0.86). The AGI and the NFE were suitable methods for assessing bacteria in this environment, but the AMS was not. The AMS was the only method that consistently recovered enteric bacteria (73% data yield). For sampling fungi, the AGI and AMS both yielded sufficient data and all three methods demonstrated high intraclass reliability.(ABSTRACT TRUNCATED AT 250 WORDS)