Evaluation of airborne dust and endotoxin in corn storage and processing facilities in Colorado

The main objectives of this research were to determine what aerosols were present by taking total dust (TD) samples and thoracic particulate mass samples (TPM) on farms and in grain elevators. Cascade impactors were used to characterize size distributions of dust and endotoxins at each site. Total dust concentrations on farms had a geometric mean 3.4 mg/m3 and 3.3 mg/m3 in elevators. The geometric mean (GM) concentrations for the TPM were 2.4 mg/m3 on farms and 1.0 mg/m3 in elevators. Endotoxin concentrations as geometric means were alarming at 3175 EU/m3 total dust and 983 EU/m3 by TPM on farms. In elevators, the GM concentrations for endotoxins were 2534 EU/m3 total dust, and 526 EU/m3 by TPM. The mass median aerodynamic diameter (MMAD) for endotoxins on farms was 8.0 microm and 6.5 microm in elevators. The paired t-test was applied to the log ratios of endotoxin concentrations (EU/m3) and dust concentrations (mg/m3), for paired samples of the TD and TPM. A higher content of endotoxins was associated with TPM for farms but not elevators. It was concluded that although the TPM fraction (dust) may represent a small part of the total mass, the aerosol size is optimum for deposition in the lung's tubular airways, and might cause airway inflammation due to the endotoxins. The TPM fraction of corn dust represents the best measure of exposure with regard to the potential development of long-term airways inflammation, and the potential of chronic obstructive pulmonary disease among chronically exposed workers. All endotoxin concentrations were well above recommended exposure levels of several researchers familiar with endotoxin health effects.     

Work area measurements as predictors of personal exposure to endotoxin and cotton dust in the cotton textile industry

OBJECTIVES: To determine if work area measurements of endotoxin and/or cotton dust obtained from the vertical elutriator (VE) can be used to predict levels of personal endotoxin exposure as measured by the Institute of Occupational Medicine (IOM) inhalable dust sampler in the cotton textile industry. METHODS: Fifty-six work area cotton dust samples were collected from 14 areas and 82 personal cotton dust samples were collected from 41 workers in three textile mills (Mills A, B and C) in Shanghai, China. Cotton dust concentrations were determined gravimetrically from sample filters, of which endotoxin concentrations were determined using a kinetic chromogenic modification of the limulus amoebocyte lysate assay. Linear regression models were used to determine the association between log IOM personal endotoxin concentration and log VE area endotoxin concentration. RESULTS: Median cotton dust and endotoxin concentrations measured from VE area samples in the three mills were 0.36 mg m(-3) and 1280.76 endotoxin units per cubic meter (EU m(-3)), respectively, compared to 1.74 mg m(-3) and 2226.83 EU m(-3) from IOM personal samples. Excluding samples from weaving processes, we observed linear associations between VE area measures of endotoxin and IOM personal endotoxin concentrations; VE area concentration of endotoxin explained 83 and 89% of the total variation in IOM personal endotoxin concentration for Mills A and B, respectively (Mill A: R2 = 0.83, P < 0.0001; Mill B: R2 = 0.89, P < 0.0001). Although area measures of cotton dust was also a significant predictor of person endotoxin, the model explained less of the variance in personal endotoxin measurements. CONCLUSIONS: Specific to the conditions of the textile mills investigated in this study, work area measurements of endotoxin, but not cotton dust, may be reasonable proxies for personal levels, at least for rank-ordering exposures.     

Dose-response relationships between occupational aerosol exposures and cross-shift declines of lung function in poultry workers: recommendations for exposure limits

Numerous articles have been published regarding the adverse respiratory health consequences of working in intensive livestock and poultry housing. Threshold limit exposure guidelines are not currently applied to this environment, but they are essential to implement and monitor effective environmental controls. Previous dose-response research work with swine workers has resulted in exposure limit recommendations of 2.5 mg/m3 total dust, 0.23 mg/m3 respirable dust, 100 EU/m3 endotoxin, and 7 ppm ammonia. No similar recommendations have been reported previously for poultry workers. Therefore, an industry-wide study was conducted to examine dose-response relationships of bioaerosol exposures and worker respiratory health. A total of 257 poultry workers were studied for respiratory symptoms, pulmonary function, and exposure to dust (total and respirable), endotoxin (respirable and total), and ammonia. Details of the sampling plan and environmental assessment are described elsewhere. Relationships between exposures and response were studied by correlation and multiple regressions. Significant dose-response relationships were observed between exposures and pulmonary function decrements over a work shift. Exposure concentrations associated with significant pulmonary function decrements were as follows: 2.4 mg/m3 total dust, 0.16 mg/m3 respirable dust, 614 EU/m3 endotoxin, and 12 ppm ammonia.     

Personal exposure of dairy workers to dust,endotoxin, muramic acid,ergosterol, and ammonia on large-scale dairies in the high plains Western United States

Dairy workers experience a high degree of bioaerosol exposure, composed of an array of biological and chemical constituents, which have been tied to adverse health effects. A better understanding of the variation in the magnitude and composition of exposures by task is needed to inform worker protection strategies. To characterize the levels and types of exposures, 115 dairy workers grouped into three task categories on nine farms in the high plains Western United States underwent personal monitoring for inhalable dust, endotoxin, 3-hydroxy fatty acids (3-OHFA), muramic acid, ergosterol, and ammonia through one work shift. Eighty-nine percent of dairy workers were exposed to endotoxin at concentrations exceeding the recommended exposure guidelines (adjusted for a long work shift). The proportion of workers with exposures exceeding recommended guidelines was lower for inhalable dust (12%), and ammonia (1%). Ergosterol exposures were only measurable on 28% of samples, primarily among medical workers and feed handlers. Milking parlor workers were exposed to significantly higher inhalable dust, endotoxin, 3-OHFA, ammonia, and muramic acid concentrations compared to workers performing other tasks. Development of large modern dairies has successfully made progress in reducing worker exposures and lung disease prevalence. However, exposure to endotoxin, dust, and ammonia continues to present a significant risk to worker health on North American dairies, especially for workers in milking parlors. This study was among the first to concurrently evaluate occupational exposure to assayable endotoxin (lipid A), 3-hydroxy fatty acids or 3-OHFA (a chemical measure of cell bound and noncell-bound endotoxins), muramic acid, ergosterol, and ammonia among workers on Western U.S. dairies. There remains a need for cost-effective, culturally acceptable intervention strategies integrated in OHS Risk Management and production systems to further optimize worker health and farm productivity.     

Modeling, estimation and validation of cotton dust and endotoxin exposures in Chinese textile operations

In support of an epidemiological study of cancer incidence among cotton textile workers in Shanghai, PRC, historical estimates of exposure to cotton dust and endotoxin were developed for subjects drawn from a cohort of 267,400 female textile workers. A large dataset of historical cotton dust measurements were available from 56 of the study factories. Using these data, a series of models were developed to estimate cotton dust exposure by year, factory and process. Model estimates were validated by comparing with independently collected measurements gathered over a 15 year period and indicated a low relative bias (< 2%) and relative accuracy (+/- 61%). Endotoxin exposures were estimated using the endotoxin content of cotton dust by major processes obtained in five separate surveys in these factories. The validated exposures were assigned to the 7,242 jobs held by the 3,812 study subjects. Among the exposed workers, the mean cumulative exposure levels were 113.8 mg m(-3)*years for cotton dust and 6,707.7 EU m(-3)*years for endotoxin, respectively. The overall correlation among cotton dust and endotoxin exposures for these subjects was r = 0.58. Using an unusually rich set of historical cotton dust measurements, along with independently collected exposure measurements for validation and conversion to endotoxin levels, validated estimates of cumulative exposure were constructed for this large case-cohort study in the textile industry.     

Worker exposures to airborne dust, endotoxin and beta(1,3)-glucan in two New Zealand sawmills

BACKGROUND: Sawmill workers have an increased risk of developing occupational asthma and other respiratory symptoms. Wood dust and microorganisms have both been suggested to play a role, but few studies have measured microbial exposure levels in sawmills. METHODS: The preliminary study reported in this paper assessed airborne dust, bacterial endotoxin and beta(1,3)-glucan levels in 37 samples from two New Zealand sawmills. RESULTS: Nearly one-third of the measured dust levels exceeded 1 mg/m(3) and only one sample exceeded the legal limit of 5 mg/m(3). Endotoxin levels were clearly elevated with 50% of all measured exposures above 50 EU/m(3) (range: 7-588 EU/m(3)). beta(1,3)-glucan levels were comparable with levels measured in other industries where workers are exposed to organic dust. Workers in the planing department had the highest mean exposures to dust, endotoxin and beta(1,3)-glucan. Dust levels were only weakly correlated with endotoxin and beta(1,3)-glucan levels. CONCLUSIONS: Endotoxin exposures in sawmill workers are at levels sufficient to potentially contribute to the development of respiratory symptoms. Moreover, measurement of dust exposure is a poor proxy for beta(1,3)-glucan and endotoxin exposure in sawmill workers.     

Exposure to wood dust and endotoxin in small-scale wood industries in Tanzania

Workers in small-scale wood industries (SSWI) have increased risks of developing asthma and other respiratory diseases. Wood dust and microbial agents have both been suggested to play a role, but few studies have measured endotoxin exposure in SSWI in Africa. We assessed inhalable dust levels in 281 samples from 115 workers and bacterial endotoxins levels in 157 samples from 136 workers from SSWI in Dar es Salaam, Tanzania. The overall geometric mean of personal exposure was 3.3 mg/m(3); geometric standard deviation (GSD) 2.5; range 0.45-67.0 mg/m(3)) and 91 EU/m(3) (GSD 3.7; range 9-4914.8 EU/m(3)) for wood dust and endotoxins, respectively. Dust and endotoxin levels were weakly correlated (r = 0.44, n = 157, P < 0.0001). Between- and within-worker variances and percentages explained by the differences among job titles and seasons were 0.31 (9%) and 0.35 (30%), respectively, for wood dust exposure, and 0.35 (0%) and 0.35 (38%) for endotoxin exposure. Higher dust and endotoxin exposure levels were observed in the dry compared to the wet season, after correcting for differences in exposure between jobs. Carving and manual cleaning were associated with the highest dust exposures. Sewing seat covers and manual cleaning were associated with the highest endotoxin exposures. Dust and endotoxin exposure levels in SSWI are high and appropriate control measures are necessary.     

Exposure to dust,endotoxin and micro-organisms in the potato processing industry

Exposure to organic dust components was studied in four potato processing plants because preliminary results showed high exposures accompanied by work-related health complaints. Ambient air concentrations of inhalable dust ranged from below 0.4 up to 44 mg m⁻³ [geometric mean (GM) 0.64 mg m⁻³]. Respirable dust concentrations were considerably lower. Personal concentrations of inhalable dust were somewhat higher, and strongly related to a few working tasks dealing with dried starch or protein. Ambient air concentrations of endotoxin ranged from 0.5 to more than 60 000 endotoxin units (EU) per m³ for the inhalable size fraction (GM = 280 EU m⁻³). For the respirable size fraction, endotoxin concentrations were lower (about the same factor as for dust). Personal endotoxin concentrations were lower than ambient air concentrations, probably because workers did not work the whole period of the shift near endotoxin sources. Endotoxin exposure was evaluated as very high; 23% of the workers had a mean exposure above 1000 EU m⁻³ (100 ng m⁻³). Differences between plants had a large influence on both dust and endotoxin exposure. A fairly good correlation was found between counts of airborne gram-negative bacteria and airborne endotoxin of the respirable size fraction. Ambient air levels of bacteria and endotoxin were strongly related to process water temperature, suggesting that exposure reduction can be achieved by lowering this temperature or by other measures that inhibit bacterial growth. We conclude that recycling of process water probably constitutes an exposure source of bacteria and endotoxin in many facilities.     

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 effects of cotton dust exposure in the cotton garnetting industry

We measured exposures to total dust, vertically elutriated dust, and endotoxin and studied acute pulmonary responses among 128 workers in the cotton garnetting and mattress assembly industries. Previous studies in this segment of industry have not characterized endotoxin exposures or related them to pulmonary responses. The median 8-hour time-weighted average total dust was 0.72 mg/m3, the median vertically elutriated dust was 0.22 mg/m3, and the median endotoxin concentration was 5.2 ng/m3. Ten percent of the subjects reported chest tightness or dyspnea on Mondays. Thirteen percent of the subjects reported symptoms of chronic bronchitis. Although there was no relationship between changes in pulmonary function across the workshift and either total dust, vertically elutriated dust, or endotoxin exposure, 13% of the subjects had greater than 5% decrements in FEV1 over the workshift.     

Assessment of swine worker exposures to dust and endotoxin during hog load-out and power washing

Field measurements of personal and area dust and endotoxin concentrations were obtained while agricultural workers performed two work tasks that have been previously unreported: hog load-out and swine building power washing. Hog load-out involves moving hogs from their pens in finishing buildings into a truck for transport to a meat processor. High pressure power washing is conducted for sanitation purposes after a building has been emptied of hogs to remove surface and floor debris. This debris consists of feed, feces, and hog dander as dust or an encrusted form. The hog load-out process necessarily increases pig activity which is known to increase airborne dust concentrations. An unintended consequence of power washing is that the material covering surfaces is forcibly ejected into the atmosphere, creating the potential for a highly concentrated aerosol exposure to workers. The load-out process resulted in a median personal inhalable mass concentration of 7.14 mg m(-) (3) and median endotoxin concentration of 12 150 endotoxin units (EU) m(-) (3). When converted to an 8-h time-weighted average for a 'total' sampler, one of the 19 samples exceeded a regulatory limit of 15 mg m(-) (3). An impinger was used to sample power washing endotoxin concentrations, which resulted in a median personal concentration of 40 350 EU m(-) (3). These concentrations were among the highest found in the literature for any occupation. With the lack of engineering controls present to reduce airborne contaminant concentrations in swine buildings, either respirator use or a reduction in exposure time is recommended while performing these tasks.     

Evaluation of five extraction protocols for quantification of endotoxin in metalworking fluid aerosol

OBJECTIVES: Occupational exposures to endotoxin-contaminated, water-based metalworking fluids (MWFs) are thought to contribute to cases of respiratory illness. Before occupational exposure limits for endotoxin can be proposed, accuracy and reproducibility of laboratory measurements must be established. The method most commonly used to quantify endotoxin is the Limulus amebocyte lysate (LAL) assay and this is the basis for the American Society for Testing and Materials (ASTM) method E2144-01. This study was conducted to generate multiple samples with similar mass and endotoxin loading in order to compare four alternative extraction methods with the ASTM method. METHODS: Using an exposure chamber system that provides a uniform distribution of MWF mist, aerosols with three concentrations of endotoxins (4.5, 350 and 1141 EU/m(3)) were collected simultaneously on multiple filter samples. The filters were examined for endotoxin concentration using five different extraction protocols: extraction with 1 h shaking at 25 degrees C in 30 ml pyrogen-free water (PFW) (protocol 1) or in PFW with 0.05% Tween-20 (protocol 2); or shaking at 68 degrees C in 30 ml PFW (protocol 3) or PFW with Tween-20 (protocol 4); or extraction into 20 ml PFW with sonication at 25 degrees C and pH adjustment to 7.5 (ASTM protocol). RESULTS: The uniformity of the aerosol mass yielded coefficients of variation of 12.7, 7.7 and 1.4% for the low, medium and high exposure groups, respectively. The variance in the endotoxin extraction protocols was highest for the ASTM method for the low, medium and high concentration trials. Low, medium and high endotoxin groups were statistically different (P < 0.001), but there were no statistical differences between extraction protocols within these exposure levels. CONCLUSIONS: ASTM method E2144-01 yielded comparable estimations of MWF endotoxin aerosol concentrations but with higher variability than the four other extraction methods. This study shows that extraction into PFW at 25 degrees C with or without Tween-20 was an improvement over the ASTM method in that the estimation was more precise and the method is simpler.     

Airborne endotoxin associated with particles of different sizes and affected by water content in handled straw

High exposures to endotoxin are observed in environments where organic materials are handled and lower exposures are found in e.g. indoor air. Inhaled endotoxin contributes significantly to the induction of airway inflammation and dysfunction. The size of an inhaled particle influences the deposition in the airways and the following health symptoms. The objective is to characterise the distribution of endotoxin on airborne particles of different sizes in straw storage halls with high exposure and in other environments with lower exposure levels to endotoxin. Furthermore we have studied the influence of water content of handled straw on the size distribution of endotoxin containing particles. Total, inhalable, thoracic and respirable endotoxin and particles have each been quantified in aerosols from boiler rooms and straw storage halls at 24 power plants, including 21 biofuel plants. Inhalable, thoracic and respirable endotoxin have been quantified in aerosols from offices and outdoor air. The endotoxin concentration was higher in airborne thoracic dust than in airborne ‘total dust’. The median respirable fraction in the straw storage halls, boiler rooms at biofuel plants, boiler rooms at conventional plants, offices and outdoors was respectively 42%, 9%, 19%, 24% and 34%. Thoracic endotoxin per number of thoracic particles was higher than respirable endotoxin per number of respirable particles at the biofuel plants. In straw storage halls the fraction of endotoxin of respirable size was highest on the days with lowest water content in the received straw. Furthermore the exposures to all endotoxin fractions were highest on days with the lowest water content in the received straw. In conclusion the highest exposures and concentrations of endotoxin occur or tend to occur from thoracic dust. A high variation in endotoxin concentrations and in fractions of respirable or thoracic size is found in the different working areas. This is important in the risk assessment and makes attempts to influence the endotoxin exposure a possibility. Water content in straw affected the concentration, exposure level and size distribution of airborne endotoxin.     

Endotoxin levels in farming: absence of symptoms despite high exposure levels.

The endotoxin concentration in air was measured in farms where 11 farmers had experienced febrile reactions or allergic alveolitis and in a random sample of farms with 17 symptomless farmers. Samples were obtained during normal dairy farming in eight reference farms (background samples) and in all farms during the handling of material which had probably caused symptoms or disease or, in reference farms, maximal spore exposure (worst case samples). In addition, parallel samplers were used in reference farms, one with a cyclone (5 microns cutoff) and one without, to measure the dust and endotoxin concentrations in the respirable fraction and total dust. The endotoxin worst case values varied from less than 0.01 to greater than 50 micrograms/m3 in symptom farms (median 6.4 micrograms/m3, geometric mean 2.2 micrograms/m3) and from less than 0.01 to greater than 50 micrograms/m3 in reference farms (median 42 micrograms/m3, geometric mean 29 micrograms/m3). This difference was not statistically significant. The background values in reference farms were 1.3 (median) and 0.4 (geometric mean) micrograms/m3. The differences between samples with and without cyclone and between background and worst case samples were statistically significant (p less than 0.02). About 75% of the activity was found in the non-respirable fraction. No correlation was found between exposure to endotoxin and symptoms in farmers. There were weak, but statistically significant, correlations between endotoxin concentrations and total spore count or dust concentrations. The surprisingly high endotoxin values in the respirable fraction of air from environments which apparently did not cause symptoms raises the concern that the Limulus amebocyte assay might be sensitive to other components in the dust rather than endotoxin.     

An HDI polyisocyanate aerosol exposure system for large-scale animal experiments

An exposure system that allows large-scale exposure of animals to 1,6-hexamethylene diisocyanate (HDI)-based polyisocyanates at a stable concentration and aerosol size distribution was developed. The HDI polyisocyanate aerosol is generated by nebulizing a solution of a commercial polyisocyanate product dissolved in acetone. The aerosol is delivered with a constant airflow into a horizontal flow chamber. Complete mixing of aerosol in the chamber is ensured by a circulating fan. This method has been used to generate atmospheres containing HDI polyisocyanates at a concentration of 10.46+/-0.23 mg/m(3) over a 5-hour period. The overall mass median aerodynamic equivalent diameter was found to be 1.42 microm with a geometric standard deviation of 1.26. The HDI monomer concentration was 0.15+/-0.04 mg/m(3). The average chamber acetone concentration was determined to be 2481+/-222 ppm (mean+/-standard deviation). Different HDI polyisocyanate concentrations in the chamber can be achieved by altering the concentration of the commercial polyisocyanate product in acetone and the chamber flow rate. The described exposure system will be useful for performing toxicological studies involving HDI polyisocyanates.     

Endotoxin levels in farming: absence of symptoms despite high exposure levels

The endotoxin concentration in air was measured in farms where 11 farmers had experienced febrile reactions or allergic alveolitis and in a random sample of farms with 17 symptomless farmers. Samples were obtained during normal dairy farming in eight reference farms (background samples) and in all farms during the handling of material which had probably caused symptoms or disease or, in reference farms, maximal spore exposure (worst case samples). In addition, parallel samplers were used in reference farms, one with a cyclone (5 microns cutoff) and one without, to measure the dust and endotoxin concentrations in the respirable fraction and total dust. The endotoxin worst case values varied from less than 0.01 to greater than 50 micrograms/m3 in symptom farms (median 6.4 micrograms/m3, geometric mean 2.2 micrograms/m3) and from less than 0.01 to greater than 50 micrograms/m3 in reference farms (median 42 micrograms/m3, geometric mean 29 micrograms/m3). This difference was not statistically significant. The background values in reference farms were 1.3 (median) and 0.4 (geometric mean) micrograms/m3. The differences between samples with and without cyclone and between background and worst case samples were statistically significant (p less than 0.02). About 75% of the activity was found in the non-respirable fraction. No correlation was found between exposure to endotoxin and symptoms in farmers. There were weak, but statistically significant, correlations between endotoxin concentrations and total spore count or dust concentrations. The surprisingly high endotoxin values in the respirable fraction of air from environments which apparently did not cause symptoms raises the concern that the Limulus amebocyte assay might be sensitive to other components in the dust rather than endotoxin.     

Acute respiratory effects in the potato processing industry due to a bioaerosol exposure.

The relation between bioaerosol exposure in the potato starch industry and work related respiratory symptoms is described. One group of workers was exposed to high dust concentrations (geometric mean up to 56.0 mg/m3) with low endotoxin and antigen concentrations (geometric mean up to 12.6 ng/m3 and 90 relative antigen units (RAU) per m3). A second group was exposed to low dust concentrations (geometric mean up to 3.9 mg/m3), but the endotoxin and antigen concentrations were high (geometric means of environmental samples up to 72 ng/m3 and 2.9.10(2)RAU/m3). Twenty of the 48 workers had specific IgG4 titres to dust extract. Of these 20 workers, 14 showed an increase in IgG4 titre during the first month of the potato processing season. No specific IgE antibodies to dust extracts were found. Twenty two workers were equipped with a Mini-Wright peak flow meter during a four week period. Two workers showed a work related decline in peak flow values. It was concluded that exposure to dust made airborne during the refining process of potato starch may cause work related respiratory symptoms.     

Nose-only exposure system for inhalation exposures of rodents to large particles

A large-particle exposure system for small animals was designed, constructed and evaluated. The system was designed by incorporating a fluidized bed aerosol generator (FBG) and a nose-only exposure device to accommodate 40 small animals into a single unit. The system has four levels of exposure ports, each level having ten exposure ports radially positioned around the aerosol delivery components of the system. The aerosol generator produces aerosols that travel to the top of the system then downwards in order to be drawn past each animal's nose via vacuum ports immediately above the exposure ports. Nearly monodisperse polystyrene latex aerosols with nominal sizes of 3.0, 9.0 and 15.0 micron were generated as dry powders in an FBG with an inside diameter of 5 cm. During 60-min test runs, average aerosol mass concentrations up to 37 mg/m3 were achieved with less than 10% variation in mass concentration distribution throughout the unit.     

Variations in exposures to dust and endotoxin in Danish piggeries.

Two surveys studied day-to-day variations in exposures to dust and endotoxin and those caused by different tasks and the content of fat in the feed. The exposure to "total" particulate matter (TPM) was just below and at the same level, respectively, as the Danish occupational exposure limit of 5.0 mg/m3 for organic dust. No variation with task distance from the animals was found, but the results indicated decreased exposure when fat was added to the feed. The endotoxin exposure level was lower than previously reported. High correlations were found between TPM, respirable dust, and endotoxin.     

Cotton dust and endotoxin levels in three Shanghai textile factories: a comparison of samplers

The results of a field survey at three Shanghai textile factories were used to compare the performance of the Chinese dust sampler (CDS) with the standard American sampler, vertical elutriator (VE). Side-by-side samples using a CDS and a VE were collected in seven specific manufacturing processes, with additional area and personal samples collected with a modified Institute of Occupational Medicine (IOM) personal inhalable sampler. Filters were analyzed for mass and endotoxin concentration. The geometric mean (GM) of the samples collected by the CDS was 0.79 mg/m3 (geometric standard deviation [GSD] 1.9) compared with a GM of 0.31 mg/m3 (GSD 1.7) for the VE measurements. The correlation coefficient for the CDS and VE samples was 0.35. The CDS, a high-volume total dust area sampler, collects 2 to 10 times more dust than the VE, a size-selective method, depending on the manufacturing process. In spinning at Factory A, the VE and CDS measured concentrations of 0.15 mg/m3 and 1.62 mg/m3, respectively. Cotton dust concentration measurements collected by the IOM sampler demonstrated that personal exposure concentrations were significantly higher (GM 1.84 mg/m3, GSD 1.6) than fixed-position area samples (GM 0.68 mg/m3, GSD 1.9). The endotoxin concentration based on the VE samples was 366 EU/m3, with the highest levels found in the specific manufacturing process drawing (1871 EU/m3) and the lowest in spinning (43.5 EU/m3). The results of the field comparison were used to convert historic CDS data into comparable exposures and to assign retrospective exposures to subjects included in a case-cohort study of lung cancer among female textile workers in Shanghai.