A 20-year follow-up study on chronic respiratory effects of exposure to cotton dust.

In order to evaluate chronic effects of long-term exposure to cotton dust on respiratory health, and the role of dust and endotoxin, longitudinal changes in lung function and respiratory symptoms were observed prospectively from 1981 to 2001 in 447 cotton textile workers, along with 472 silk textile controls. The results from five surveys conducted over the 20-yr period are reported, including standardised questionnaires, pre- and post-shift spirometric measurements, work-area inhalable dust sample collections and airborne Gram-bacterial endotoxin analysis. Cotton workers had more persistent respiratory symptoms and greater annual declines in forced expiratory volume in one second (FEV1) and forced vital capacity as compared with silk workers. After exposure cessation, in the final 5-yr period, the rate of FEV1 decline tended to slow in nonsmoking males, but not in nonsmoking females. Workers who reported byssinotic symptoms more persistently suffered greater declines in FEV1. Chronic loss in lung function was more strongly associated with exposure to endotoxin than to dust. In conclusion, the current study suggests that long-term exposure to cotton dust, in which airborne endotoxin appears to play an important role, results in substantial adverse chronic respiratory effects.

Respiratory symptoms and cotton dust exposure; results of a 15 year follow up observation.

AIMS: To determine chronic effects of long term exposure to cotton dust and endotoxin on incidence of respiratory symptoms and the effect of cessation of exposure. METHODS: Respiratory health in 429 Chinese cotton textile workers (study group) and 449 silk textile workers (control group) was followed prospectively from 1981 to 1996. Byssinosis, chest tightness, and non-specific respiratory symptoms were assessed by means of identical standardised questionnaires at four time points. Exposures to cotton dust and endotoxin were estimated using area samples collected at each survey. Incidence and persistence of symptoms were examined in relation to cumulative exposure and exposure cessation using generalised estimating equations (GEE). RESULTS: Among cotton workers, the cumulative incidence of byssinosis and chest tightness was 24% and 23%, respectively, and was significantly more common in smokers than in non-smokers. A high proportion of symptoms was found to be intermittent, rather than persistent. Among silk workers, no typical byssinosis was identified; the incidence of chest tightness was 10%. Chronic bronchitis, cough, and dyspnoea were more common and persistent in the cotton group than in the silk group. Significantly lower odds ratios for symptoms were observed in cotton workers who left the cotton mills; risk was also related to years since last worked. Multivariate analysis indicated a trend for higher cumulative exposure to endotoxin in relation to a higher risk for byssinosis. CONCLUSION: Chronic exposure to cotton dust is related to both work specific and non-specific respiratory symptoms. Byssinosis is more strongly associated with exposure to endotoxin than to dust. Cessation of exposure may improve the respiratory health of cotton textile workers; the improvement appears to increase with time since last exposure.

Longitudinal changes in pulmonary function and respiratory symptoms in cotton textile workers. A 15-yr follow-up study.

To evaluate the chronic effects of exposure to cotton dust, a 15-yr follow-up study in cotton textile workers was performed in Shanghai, China from 1981 to 1996. Testing occurred four times during the 15-yr period. The achieved follow-up rates were 76-88% of the original 447 cotton textile workers, and 70-85% of the original 472 silk textile workers (as a control group). Identical questionnaires, equipment, and methods were used throughout the study. The prevalence of byssinosis increased over time in cotton workers, with 15.3% at the last survey versus 7.6% at the baseline, whereas no byssinosis was found in silk workers. More workers in the cotton group consistently reported symptoms than in the silk group, although symptom reporting varied considerably from survey to survey. Cotton workers had small, but significantly greater, adjusted annual declines in FEV(1) and FVC than did the silk workers. Years worked in cotton mills, high level of exposure to endotoxin, and across-shift drops in FEV(1) were found to be significant determinants for longitudinal change in FEV(1), after controlling for appropriate confounders. Furthermore, there were statistically significant associations between excessive loss of FEV(1) and byssinosis, chest tightness at work, and chronic bronchitis in cotton workers. Workers who consistently (three or four of the surveys) reported byssinosis or chest tightness at work had a significantly greater 15-yr loss of FEV(1). We conclude that long-term exposure to cotton dust is associated with chronic or permanent obstructive impairments. Consistent reporting of respiratory symptoms, including byssinosis and chest tightness at work, is of value to predict the magnitude and severity of chronic impairments in textile workers.

Splenic injury after intraoperative transesophageal echocardiography.

A 55-year-old woman underwent coronary artery bypass grafting and mitral valve repair using intraoperative transesophageal echocardiography (TEE). Postoperatively she had hemodynamic instability associated with an increase in abdominal size and a drop in hemoglobin. At laparotomy, a splenic hilar laceration was discovered, which was presumed to be associated with intraoperative TEE. She underwent emergent splenectomy. This case demonstrates that although rare, serious complications can occur with TEE.

Cotton dust and endotoxin exposure and long-term decline in lung function: results of a longitudinal study.

BACKGROUND: To evaluate the relationship between long-term exposure to cotton dust and Gram-negative bacterial endotoxin on lung function, we conducted an 11-year follow-up study of cotton textile workers in Shanghai, China. METHODS: Workers at a nearby silk-thread manufacturing mill were used as a referent population. Ninety percent of the original cohort of 445 cotton and 467 silk textile workers--both active and retired--were identified for testing in the 11th year. Questionnaires and spirometric testing were performed, as well as cotton dust and endotoxin sampling at three points over the 11-year follow-up period: at baseline, at Year 5, and at Year 11. After excluding deaths and subjects on sick-leave, 84% of the original cohort had complete health and environmental data. RESULTS: The data were reanalyzed using generalized estimating equations feedback model which allow for subject transfer over time between work areas, various exposure levels to dust and endotoxin, and FEV1. Cotton workers had a larger loss of FEV1 during the first 5 years of study (-40 mls/yr) as compared with the second 6 years of follow-up (-18 mls/yr). During the same periods, the average decline among silk workers was slightly higher in the first period, but was more consistent (-30 mls/yr vs. -27 mls/yr), and these differences could not be explained by worker selection or dropout. When cumulative exposure to dust and endotoxin were estimated and used in a multivariate model (GEE) for FEV1 loss, cumulative dust, but not endotoxin, was associated with 11-year loss in FEV1 after adjustments for confounders. There was evidence of feedback between dust-exposure levels and FEV1, indicating the existence of a healthy-worker survivor effect. After accounting for a healthy-worker survivor effect, we found a significant relationship between dust exposure and FEV1 decline. CONCLUSIONS: Our results suggest that cotton dust is more strongly associated with chronic airflow limitation than associated endotoxins. Further work is needed to clarify potential reversibility after cessation of exposure, and the relative contributions of dust, endotoxin, and tobacco to chronic respiratory impairment in cotton and other vegetable-exposed workers.

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.

Neutrophilic respiratory tract inflammation and peripheral blood neutrophilia after grain sorghum dust extract challenge.

STUDY OBJECTIVE: To determine if inhalation of grain sorghum dust in the laboratory would cause neutrophilic upper and lower respiratory tract inflammation in human volunteers, as well as systemic signs of illness. DESIGN: Prospective. SETTING: University of Nebraska Medical Center. PARTICIPANTS: Thirty normal volunteers. INTERVENTIONS: Inhalation challenge with 20 mL of a nebulized solution of filter-sterilized grain sorghum dust extract (GSDE). One group received prednisone, 20 mg for 2 days, prior to the challenge. MEASUREMENTS AND RESULTS: Bronchoscopy with bronchoalveolar lavage (BAL) was performed 24 h after challenge, with samples collected as bronchial and alveolar fractions. Findings included visible signs of airways inflammation, quantified as the bronchitis index. The percentage of bronchial neutrophils was significantly increased in those challenged with GSDE vs the control solution, Hanks' balanced salt solution (40.3 +/- 4.5% vs 14.3 +/- 5.1%, p < or = .01). Similar findings were seen in the alveolar fraction. Pretreatment with corticosteroids did not prevent the rise in neutrophils recovered by BAL. Peripheral blood neutrophils were also increased in volunteers challenged with the grain dust extract. To explain the increase in peripheral blood neutrophil counts, the capacity of the peripheral blood neutrophils to migrate in chemotaxis experiments was examined. The results demonstrate an increase in peripheral blood neutrophils and an increase in chemotactic responsiveness. CONCLUSIONS: Inhalation challenge with a grain dust extract causes respiratory tract inflammation and a peripheral blood neutrophilia. One reason for this may be an increase in activated peripheral blood neutrophils.

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.

Determinants of longitudinal changes in spirometric function among swine confinement operators and farmers.

To assess whether working in a swine confinement facility causes an excess or accelerated decline in lung function, we conducted a population-based study to evaluate the determinants of longitudinal changes in airflow in a population of swine confinement operators. Spirometric measures of lung function were compared between swine confinement operators (N = 168) and neighborhood farmer control subjects (N = 127). Study subjects were randomly selected from a cohort of swine confinement operators in eastern Iowa. The control farming population was matched by geographic location, age, and sex to the swine confinement operators. On average, the follow-up time was approximately 2 yr, with a range of follow-up between 56 and 1,900 d. Although swine confinement operators and neighborhood farmers had similar demographic characteristics (age, gender, racial background, smoking history, and atopy status), swine confinement operators tended to have less farming experience and were more extensively followed (more measures of lung function and longer periods of observation) than the neighborhood farmer control group. Swine confinement operators were also exposed to higher environmental dust concentrations and other irritants than the farmer control subjects. Interestingly, the cross-sectional data indicated that swine confinement operators tended to have slightly lower measures of airflow and greater workshift declines in forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and mid-expiratory flow (FEF25-75) than the neighborhood farmer control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Respiratory health status in swine producers relates to endotoxin exposure in the presence of low dust levels.

We conducted an assessment of respiratory health status including questionnaire and spirographic measurements in 54 male swine producers age 36.3 +/- 11.1 years (mean +/- SD) who worked an average of 10.7 +/- 6.3 years in the industry and spent 4.7 +/- 2.1 hours per day in the swine barns, and we also measured atmospheric contaminants including carbon dioxide, ammonia, total dust, respirable dust, and airborne endotoxin. Mean atmospheric dust contaminant levels were as follows: carbon dioxide, 2632 +/- 807 ppm; ammonia, 11.3 +/- 4.2 ppm; total dust, 2.93 +/- 0.92 mg/m3; respirable dust, 0.13 +/- 0.05 mg/m3; and endotoxin, 11,332 +/- 13,492 endotoxin units/m3. Of these, endotoxin related to forced vital capacity (P < .05) and endotoxin x hours per day was related to forced vital capacity (P < .05) and to forced expiratory volume in 1 second (P = .06). Respiratory symptoms and lung function studies did not relate to categories of low, medium, and high exposure to respirable dust. However, categories of endotoxin (available on 46 workers) related to respiratory symptoms (cough, P = .02; chronic bronchitis, P = .06; and to forced vital capacity, P < .01). These data suggest that respiratory health status relates to endotoxin levels but not to dust level exposures in the presence of low dust levels and indicates that control measures should include endotoxin as well as dust control.

Airborne endotoxin concentrations in various work areas within a cotton mill in Central America.

Gram-negative bacteria and their endotoxins have been shown to cause profound changes in the structure and function of mammalian lungs. Airborne exposures in humans have resulted in bronchoconstriction and symptoms of chest tightness and dyspnea. Cotton dust is often heavily contaminated and endotoxin has been postulated to be the agent in cotton dust which is responsible for the byssinosis syndrome. Previous studies of cotton dust have revealed variable amounts of contamination by bacterial endotoxin, with the variability determined in large part by botanical and climatic characteristics. We report here the results of an environmental study conducted in a cotton mill located in the tropics of Central America using locally grown cotton. Results indicate that airborne endotoxin was present in all yarn preparation and weaving areas and ranged from a low of 18 EU/m3 in weaving to a high of 3138 EU/m3 in opening areas. Airborne levels and the amount of endotoxin per nanogram of dust were not higher than values obtained in temperate climates.

Cotton dust and gram-negative bacterial endotoxin correlations in two cotton textile mills.

Exposure to cotton dust is known to cause both acute and chronic respiratory illness. A specific pattern of symptoms called byssinosis is well described to occur among workers in the cotton processing (e.g., yarn preparation) industry. Recent studies have implicated Gram-negative bacterial endotoxin as one of the agents responsible for acute, and possibly chronic, respiratory illness. Laboratory experiments using a model cardroom have found poor correlations between airborne dust and associated endotoxin. This study reports the results of vertical elutriated dust and endotoxin levels in 11 work areas of 2 cotton textile mills in 1986 in Shanghai, China. The overall correlation between dust and endotoxin was strong, rs = 0.66 and 0.79 (p < 0.0001) for mills 1 and 2, respectively. The dust-endotoxin correlation was relatively poor in early yarn preparation in the workshops and improved in the later preparation areas. Our findings suggest that in these mill settings, dust and endotoxin levels may be well correlated in most work areas. Therefore, dust may be a useful index for monitoring populations employed in the cotton textile industry throughout the world. Additional field studies need to be performed which consider the various determinants of dust and endotoxin levels.

Histamine and endotoxin contamination of hay and respirable hay dust.

Three distinct samples collected from a barn in which an outbreak of respiratory problems occurred were examined for possible etiologic agents. No causal relationship could be established from the results of this study; however histamine concentrations as high as 0.5 ng/mg for bulk hay (in the absence of measurable creatinine levels) along with 6138.3 endotoxin units/mg of hay were present in the samples. Both endotoxin and histamine could be recovered from respirable hay dust. The authenticity of the histamine found in the hay was evaluated with high-performance liquid chromatography and radioimmunoassay. Histamine release caused by hay extracts was evaluated with the use of leukocytes from the farmer and a referent. Histamine is known to modulate the immune system, but the role of occupational or environmental exposure to histamine in respiratory disease is unknown.

Symptoms and microenvironmental measures in nonproblem buildings.

Symptoms commonly defined as the sick building syndrome were studied in a cross-sectional investigation of 147 office workers in five building areas using a linear-analog self-assessment scale questionnaire to define symptoms at a specific point in time. At the same time, the environment in the breathing zone was characterized by measuring thermal parameters (dry-bulb temperature, relative humidity, air speed, and radiant temperature), volatile organic compounds, respirable suspended particulates, noise and light intensity, and carbon dioxide and carbon monoxide levels. Demographic characteristics of the occupants and building characteristics were recorded. Up to 25% of the variance in regression models could be explained for mucous membrane irritation and central nervous system symptoms. These two symptom groups were related to the concentrations of volatile organic compounds, to crowding, to layers of clothing, and to measured levels of lighting intensity. Chest tightness was also related to lighting intensity. Skin complaints were related only to gender. Gender, age, and education failed to demonstrate a consistent relationship with symptom categories. This study suggests that the sick building syndrome may have specific environmental causes, including lighting and volatile organic compounds.

Airborne endotoxin concentrations in various work areas within two cotton textile mills in the People's Republic of China.

As part of a multidisciplinary longitudinal approach to assess the roles of airborne cotton dust and endotoxins in affecting the respiratory health of cotton textile workers, this study was designed to quantify the endotoxin contamination of airborne vertically elutriated and total dusts. Yarn preparation areas (opening through fine spinning) were studied at two cotton textile mills which had been studied 5 years previously in Shanghai. People's Republic of China, Filter, with vertically elutriated (VE) or total dusts were mailed to the United States and endotoxin analyses were performed for each filter in duplicate with the quantitative chromogenic modification of the Limulus amebocyte lysate assay. Dusts from all areas of the textile mills contained endotoxins. Endotoxin burdens in VE dusts from the carding area were similar in both milk while the endotoxin contamination of total dust from carding in Mill 1 was over threefold greater than that of total dust from carding in Mill 2. All other areas differed between milk in both VE and total dust endotoxin burdens. Mean endotoxin levels in VE dusts from all areas of both mills were well above the reported threshold of 90 EU/m3 for acute pulmonary function effects in humans. Comparison of selected areas of both mills from the present study with the same work areas from the previous study showed that, in general, the airborne endotoxin burden was higher than levels found 5 years ago in these two mills. The data suggest that even with reduced or unchanged gravimetric dust levels in these two cotton textile mills, airborne endotoxin levels were higher and provided an increased potential for adverse respiratory response in exposed workers.

Microbiological analyses and inflammatory effects of settled dusts from rice and hay.

Fourteen samples of settled dust from two factories processing rice and wheat straw near Shanghai, China, were examined by dilution plating for total bacteria, gram-negative bacteria, thermophilic actinomycetes, and fungi. They were also examined for aflatoxin, endotoxin, and potential to stimulate production of human interleukin 1 beta (IL-1 beta) and to consume complement. The concentrations of total microorganisms were consistently greater than 10(7) CFU/g and ranged from 10(7) to 10(9) CFU/g. In general, the level of microbial contamination was greater in the hay dust samples than in the rice dust samples, with bacteria being the most numerous microorganisms observed followed by molds, thermophilic actinomycetes, and yeasts. The predominant fungi were species of Aspergillus, Cladosporium, Penicillium, Trichosporon, and Cryptococcus. No significant levels of aflatoxin were observed and the isolates of A. flavus examined lack significant aflatoxigenic potential. The levels of microorganisms in these samples, the types of organisms found, and the inflammatory mediators such as endotoxin suggest that workers exposed to these dusts may be at risk for respiratory illness.