Robert M. Castellan

Inhaled endotoxin and decreased spirometric values. An exposure-response relation for cotton dust

The early stages of byssinosis, the chronic lung disorder caused by the inhalation of cotton dust, are characterized by repeated episodes of mild and reversible obstruction of airways on exposure to cotton dust. To define the relation between exposure to endotoxin and the airway response to inhaled cotton dust, we pooled and analyzed data from several previous studies of experimental exposure. The pooled data set involved a total of 108 separate sessions of exposure to dust and 32 different cottons. Each dust-exposure session had involved exposing a group of 24 to 35 prescreened healthy subjects to dust from one of the cottons for six hours. The following data were obtained for each session: average concentrations of airborne dust (range, 0.12 to 0.55 mg per cubic meter) and endotoxin (range, 6 to 779 ng per cubic meter) as determined in air samples collected by vertical elutriators, and group mean percentage change in forced expiratory volume in one second (range, +0.5 to -9.1 percent), as determined by preexposure and postexposure spirometry. When data from the 108 exposure sessions were pooled, the dust concentration was not correlated with the group mean percentage change in forced expiratory volume in one second (r = -0.08; P = 0.43). In contrast, a clear exposure-response relation was observed between endotoxin concentration and group mean percentage change in forced expiratory volume in one second (r = -0.74; P less than 0.0001). Logarithmic transformation of endotoxin values clarified this relation at low-exposure concentrations and improved the correlation (r = -0.85; P less than 0.0001). Our observations strongly support the hypothesis that endotoxin has a causative role in the acute pulmonary response to inhaled cotton dust.

Acute bronchoconstriction induced by cotton dust: dose-related responses to endotoxin and other dust factors.

Fifty-four healthy humans, selected for their acute airway responsiveness to cotton dust, had spirometric tests immediately before and after 6 hours of exposure to card-generated cotton dust from seven different cottons (of several grades and growing regions). During exposures, we measured airborne concentrations of viable fungi and bacteria (total and gram negative), vertically elutriated gravimetric dust, and vertically elutriated endotoxin. Correlation between each of these five exposure indices and exposure-related acute changes in forced expiratory volume in 1 s showed a statistically significant relationship between all of the indices except concentration of viable fungi. Of the other four indices, endotoxin was the most highly correlated (r = -0.94; p less than 0.00001), and gravimetric dust was the least correlated (r = -0.34; p less than 0.05). These findings suggest that gram-negative endotoxin may play a major role in the acute pulmonary response to inhaled cotton dust.

Acute Upper and Lower Respiratory Effects in Wildland Firefighters

Objectives: To assess acute respiratory effects experienced by wildland firefighters. Methods: We studied two Interagency Hotshot Crews with questionnaires, spirometry, and measurement of albumin, eosinophilic cationic protein (ECP), and myeloperoxidase (MPO) as indicators of inflammation in sputum and nasal lavage fluid. Assessments were made preseason, postfire, and postseason. Results: Fifty-eight members of the two crews had at least two assessments. Mean upper and lower respiratory symptom scores were higher postfire compared to preseason (P < 0.001). The mean forced expiratory volume in 1 second was lower postfire compared to preseason (P < 0.001) and then recovered by postseason. Individual increases in sputum and nasal ECP and MPO from preseason to postfire were all significantly associated with postfire respiratory symptom scores. Conclusions: Wildland firefighting was associated with upper and lower respiratory symptoms and reduced forced expiratory volume in 1 second. Within individuals, symptoms were associated with increased ECP and MPO in sputum and nasal lavage fluid. The long-term respiratory health impact of wildland firefighting, especially over multiple fire seasons, remains an important concern.

Guidelines for the epidemiologic assessment of occupational asthma: Report of the Subcommittee on the Epidemiologic Assessment of Occupational Asthma, Occupational Lung Disease Committee

Physician reporting of cases of communicable disease has played an important role in detection and control of disease outbreaks.’ A similar expectation exists for physician reporting of occupational diseases, including occupational asthma. The diagnosis of a single case of occupational asthma may be a sentinel event that reveals the need to search for other cases, as well as remediable underlying causes.’ As stated by Rutstein et al.,3 such an occurrence may: “(1) provide the impetus for epidemiologic or industrial hygiene studies, or (2) serve as a warning signal that materials substitution, engineering control, personal protection, or medical care may be required.” Also, other purposes may be served by consequent epidemiologic and industrial hygiene studies. An epidemiologic survey may be needed to convince responsible parties that a health problem exists that is in some measure attributable to workplace exposures. An epidemiologic survey will be needed to quantitate the magnitude of a work-related health problem, whether the magnitude is expressed as disease prevalence, incidence, or some other measure. An epidemiologic study may identify personal risk factors that explain why certain persons have manifested a disease as a consequence of their occupational exposure(s). Resultant recommendations for control of exposures in the workplace may facilitate management of the index case and affected co-workers, and help prevent the occurrence of additional cases.

Silicosis Mortality Surveillance in the United States, 1968–1990

Abstract The temporal, demographic, geographic, and occupational patterns of silicosis mortality in the United States were examined based on the national multiple-cause-of-death data available since 1968 from the National Center for Health Statistics. Since silicosis is an occupational lung disease, decedents less than 15 years old were excluded. The total number of deaths with silicosis was 13,744 for the period 1968 to 1990, and silicosis was the underlying cause of death in approximately 46 percent of these deaths. Approximately 98 percent of deaths with silicosis occurred in males. The racial distribution of decedents with silicosis was 88.4 percent white, 11.3 percent black, and 0.3 percent other races. An annual maximum of 1157 silicosis deaths occurred in 1968 and a minimum of 301 occurred in 1988. The annual age-adjusted mortality rate per million population declined from a maximum of 5.64 in 1968 to a minimum of 0.96 in 1988 and 1989. In recent years the annual silicosis death counts and rates ha...

Epidemiologic investigation of respiratory morbidity at a nylon flock plant

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

Prevalence of Chest Symptoms in Nonexposed Blue-Collar Workers

Epidemiological investigations of lung disease induced by occupational exposures often require prevalence estimates for various respiratory symptoms in subjects without the exposure in question. A standard respiratory questionnaire was administered to carefully selected, nonexposed blue-collar workers (n = 1,372), and linear logistic prediction equations were developed for nine symptoms. For each smoking status, equations were fit employing race, sex, age, height, weight, and education as independent variables. These results can be used as descriptive statistics, as prediction equations from an external control group, and as a guide for selecting risk factors for adjustment of symptom prevalences in other population studies.

Knuckle pads in live‐chicken hangers

A study of live‐chicken hungers in a poultry processing plant demonstrated a high prevalence of callosities over the knuckles (knuckle pads)of both hands, Knuckle pads were observed in 56% (23/41) of live‐chicken hangers, but in no (0.41)workers from other departments (p<0.001)The probable cause was the repeated striking and sliding of knuckles against metal shackles in which live birds were being plated. Additional medical and ergonomic evaluation would be worthwhile to confirm the cause, to determine whether associated tissue disorders are present in the digits of chicken hangers who develop knuckle pads, and to suggest preventive measures.

Effects of Differences in Areas of Growth and Plant Varieties on Endotoxin Contamination of Airborne Dusts from Carded Cottons

Endotoxins can exert profound biological effects both in vivo and in vitro (Morrison and Ulevitch, 1978; Bradley, 1979). However, the role of gram-negative bacteria or their endotoxins in the etiology or exacerbation of the acute pulmonary reaction to inhaled cotton dusts remains to beclarified. Gram-negative bacteria have been shown to be associated with the cotton fiber (Neal et al. , 1942; Helander and Lounatmaa, 1981; Millner et al. , 1982), and electron microscopic examination of cotton fiber revealed the shedding of the lipopolysaccharide-containing outer membrane of cotton-related organisms (Helander and Lounatmaa, 1981; Lounatmaa and Helander, 1982). Card-generated cotton dusts likewise contain the bacterial sources of endotoxins (Millner et al. , 1984), and endotoxins are quantified readily in the elutriated dusts (Olenchock, et al. , 1984). Comparisons between the acute pulmonary function response of human subjects who were exposed to card-generated cotton dusts and the concentration of endotoxins in those dusts were correlated highly ( Castellan et al. , 1984; Olenchock et al. , 1984; Rylander et al. , 1985). Thus, the presence of gram-negative bacterial endotoxins in cotton dusts must be examined for possible relationships to acute, and perhaps chronic, pulmonary changes in cotton dust-exposed individuals.

Helium-oxygen spirometry in experimental cotton dust exposure

Acute lung function responses to cotton dust were examined in 50 healthy adult volunteers known to respond acutely to cotton dust inhalation. Pre- and post-exposure air and helium-oxygen spirometry and specific airways conductance were employed for this purpose. Exposures were carefully controlled in a room ventilated with air from a model cardroom, lasted 6 h each, and were separated by 48 h intervals. Cotton dust exposure produced significant decrements in specific airways conductance (P<0.02), and in vital capacity, maximum expiratory flows breathing air (P<0.004) and on 80% helium-20% oxygen (HeO2) gas mixture (P<0.004). Cigarette smokers tended to have greater spirometric responses to cotton dust than nonsmokers, but differences between the groups were significant only for peak flow rate (PFR) andmax25 breathing HeO2 (P<0.05). Density dependence, defined as the mean HeO2:air ratio formax50 andmax25, was unaffected by cotton dust exposure. Changes in density dependence were not observed over shifts or between control and cotton dust exposures (P>0.05). This was true for the group as a whole as well as for the various smoking subgroups. The occurrence of central (SGAW, PFR, FEV1) and peripheral (max50,max25) airways narrowing among our subjects may explain the absence of a density dependence response to the levels of cotton dust used. Since only MEFV curves were employed, however, our ability to detect changes in density dependence may have been limited by the potential effect of the vital capacity maneuver on airways tone.