Respiratory response to endotoxin and dust predicts evidence of inflammatory response in volunteers in a swine barn.

BACKGROUND: It has been shown that exposure in intense exposure in swine barn facilities is associated with increased respiratory symptoms and reduction in pulmonary functions. This study investigated if systemic response could be predicted by FEV(1) response following swine barn exposure. METHODS: Naïve males were tested at baseline, low and high endotoxin and dust levels. Subjects were classified as "more responsive" (n = 9) or "less responsive" (n = 11) based on FEV(1) reduction following high endotoxin exposure. Health measures included pulmonary function testing, blood samples and nasal lavage. Environmental samples were collected from the barn. RESULTS: White blood cells and blood lymphocytes at low exposure were significantly greater in those who were "more responsive" compared to those who were "less responsive". There was a significant increase in blood lymphocytes, serum IL6, total nasal lavage cells and nasal IL8 at high exposure among "more responsive" subjects compared to "less responsive" subjects. CONCLUSIONS: Respiratory response to high-level endotoxin and dust exposure predicts evidence of inflammatory response throughout a range of endotoxin and dust exposures.

Positive human health effects of wearing a respirator in a swine barn.

STUDY OBJECTIVES: A study was conducted to evaluate the acute health effects of wearing an N-95 disposable respirator in a swine confinement facility. DESIGN: A crossover trial design was used in the study. SETTING: The study was carried out at the research facilities of the Centre for Agricultural Medicine, the Royal University Hospital, and the Prairie Swine Centre Inc, Saskatoon, Saskatchewan, Canada. PARTICIPANTS: Twenty-one nonsmoking healthy male subjects with no previous swine barn exposure participated in the study. INTERVENTIONS: The subjects participated in a laboratory session (baseline day), a 4-h exposure in a traditional swine room wearing the respirator (intervention day), and a 4-hour exposure in a traditional swine room without a respirator (nonintervention day). MEASUREMENTS: Lung function, methacholine challenge tests, blood counts, nasal lavage, and cytokines in serum and nasal lavage fluid. RESULTS: Mean (+/- SE) shift change in FEV(1), from preexposure to postexposure, was highest on nonintervention day (-8.1+/-1.01%) and was significantly different from intervention day (0.32+/-0.62%; p<0.0001) and baseline day (1.57+/-0.51%; p<0.0001). Similar patterns were observed in the mean values of the provocative concentration of a substance (methacholine) causing a 20% fall in FEV(1) (nonintervention day, 130.4+/-36.9 mg/mL; intervention day, 242.0+/-38.0 mg/mL; and baseline day, 328.0 mg/mL +/-34.1 mg/mL). Significant increases in serum neutrophil levels and nasal cell counts were observed on the nonintervention day in comparison to the baseline and intervention days. Significant increases also were found in the levels of cytokines interleukin (IL)-6 and IL-8 in nasal lavage fluid and in the levels of IL-6 in serum for the nonintervention day in comparison to the other 2 days. CONCLUSIONS: The results demonstrate that an N-95 disposable respirator can help to significantly reduce acute negative health effects in subjects not previously exposed to a swine barn environment.

Predictors of longitudinal changes in pulmonary function among swine confinement workers.

OBJECTIVE: To determine predictors of longitudinal changes in pulmonary function in swine confinement workers. DESIGN: Longitudinal study conducted from November 1989 to June 1991 and January 1994 to May 1995. SETTING: Swine confinement workers in Saskatchewan. PARTICIPANTS: Forty-two swine confinement workers who were studied in 1989/90 and studied again in 1994/95. RESULTS: Of 98 male swine confinement workers (mean age SD 36.3 11.1 years) studied at baseline, 42 were studied again five years following. Complete information on baseline across-shift pulmonary function (preshift forced expiratory volume in 1 s [FEV1], forced vital capacity [FVC], and every 2 h FEV1 and FVC during the shift), and five-year follow-up pulmonary function (with FEV1 and FVC) were available on all 42 subjects. Mean across-shift changes (preshift measurement to last measurement of the day) at baseline were -159. 8 61.7 mL in FEV1 and -35.3 65.6 mL in FVC. Mean annual rate change between baseline and follow-up for FEV1 was -53.9 61.7 mL/year and for FVC -48.9 71.6 mL/year. After adjusting for age, height, smoking and hours spent in the barn, the baseline across-shift change in FEV1 and FVC was a significant predictor of annual rate change in FEV1 (P=0.01) and FVC (P=0.02), respectively. To determine the effects of indoor air quality on longitudinal lung function decline, indoor air environmental measurements were analysed. Complete information on respiratory health and indoor air quality was available on 34 of the 42 subjects. Assessment of indoor environment of swine barns included a summer and winter measurement for airborne dust, gases and endotoxin levels. After adjusting for age, height, smoking, ammonia and hours spent in the barn, the endotoxin level (Eu/mg)was a significant predictor of annual rate change for FEV1 but not FVC. CONCLUSIONS: These results suggest that shift change is an important predictor of longitudinal changes in lung function in swine confinement workers and that endotoxin exposures may mediate annual decline in FEV1 in these workers.

Positive human health effects of dust suppression with canola oil in swine barns.

A crossover trial was conducted to evaluate the acute human health effects of a dust control technology in a swine confinement facility. Twenty lifetime nonsmoking male subjects, with no evidence of allergy or asthma and no previous swine barn exposure, participated in the study, which included a laboratory session (baseline), 5-h exposure in a swine room sprinkled with canola oil (treatment) and 5-h exposure in a traditional swine room (control). Mean values of inhalable dust concentrations and endotoxin levels in the control room were significantly greater than those observed in the treatment room. Mean shift changes in FEV1 from preexposure to end of exposure were 1.1% (standard error, 0.63%) on baseline day, -1.9% (0.63%) on treatment day, and -9.9% (1.12%) on control day; the differences in the shift changes were statistically significant. Mean value of methacholine concentration that reduced the FEV1 by 20% (PC20) in bronchoprovocation tests on baseline day was significantly different from that on treatment day (p = 0.04) and that on control day (p < 0.001). Significant increases were also observed in white blood cell counts and nasal lavage cell counts on the control day in comparison with the other two days. Blood neutrophil counts after control room exposure were twice those observed on baseline and after exposure to the treatment room. Significant differences were also observed in IL-1 beta, IL-6, and IL-8 nasal lavage cytokines and in IL-6 serum cytokine. These results suggest that the canola oil dust control method is effective in improving indoor air quality in swine barns and reducing acute health effects in naive healthy subjects.

Accelerated lung function decline in swine confinement workers.

We conducted a longitudinal study to determine the annual rate decline in pulmonary function measurements in male swine confinement workers. For comparison, a grain farming group and a nonfarming rural-dwelling control group were also chosen for the longitudinal study. Two hundred seventeen swine confinement workers, 218 grain farmers, and 179 nonfarming control subjects had valid pulmonary function measurements at the baseline observation conducted in 1990 to 1991 and at the second observation conducted in 1994 to 1995. The swine confinement workers were younger (mean age=38.3+/-11.7 [SD] years) than the nonfarming control subjects (42.6+/-10.4 years) and the grain farmers (44.5+/-11.9 years). When stratified by age, nonfarming control subjects had the lowest mean annual rate decline in FEV1 and FVC in all age categories. The swine confinement workers had the largest annual rate decline in FEV1 and FVC, and this was most obvious in the middle age categories. After controlling for age, height, smoking, and baseline pulmonary function, swine confinement workers had excess annual decline of 26.1 mL in FEV1 (p=0.0005), 33.5 mL in FVC (p=0.0002), and 42.0 mL/s in forced expiratory flow between 25% and 75% of FVC (FEF[25-75%]) (p=0.02) over nonfarming control subjects. Grain farmers had excess annual decline of 16.4 mL in FEV1 (p=0.03), 26.7 mL in FVC (p=0.002), and 11.2 mL/s in FEF(25-75%) (p=0.38) over control subjects. These findings suggest that workers engaged in the swine industry and grain farmers appear prone to accelerated yearly losses in lung function and may therefore be at risk for the future development of chronic airflow limitation.

Bacterial and fungal flora of dust deposits in a pig building.

OBJECTIVE: The purpose of the study was to investigate the bacterial and fungal flora of dust deposits in a newly built pig grower finisher building. Viable bacterial counts and microbial species found in a barn which had never housed pigs were compared with those in a barn housing 144 pigs. METHODS: The quantitative streak plate method was used to measure viable bacterial counts on nutrient agar or sheep blood agar. Viable bacterial counts of the dust deposits were expressed as the number of colony forming units (CFUs)/mg of dust. Gram positive cocci and Gram negative bacilli were identified by an automated system. Identifications with a confidence interval > 90% were accepted at the species level. Fungi were identified to the genus level with slide culture preparations on cereal agar. RESULTS: The lowest viable bacterial count (4.8 x 10(4)/mg of dust) was found in the barn with no pigs. In the barn with pigs the highest viable bacterial count (2.1 x 10(6)/mg of dust) was in dust from the top of a partition close to pig activity. Six species of bacteria or fungi were found in dust from the room with no pigs, whereas 22 different microorganisms were detected in dust from the room with pigs. With the exception of Enterobacter agglomerans no other species of the family Enterobacteriaceae was found in dust deposits in this new pig building. Twelve species of Gram positive bacteria were found in the room housing pigs. CONCLUSIONS: The pig is not only a source but also a disperser of airborne bacteria in pig buildings. Speciation of the microbial flora in dust from the pig building suggests that many of the microorganisms were either of human or environmental origin. Nevertheless as some of these microorganisms are known opportunistic pathogens or allergens and because of the documented increased incidence of chronic respiratory symptoms in pig workers, precautions to reduce inhalation of microbial or dust particles by pig workers seem prudent.

Respiratory health status in swine producers using respiratory protective devices.

A cross-sectional survey on respiratory health in swine producers showed that 30% of 301 examined men usually used a dust mask when working inside a barn. They did not differ significantly from dust mask nonusers in respect to respiratory symptoms and lung function. This analysis was undertaken to determine whether the respiratory health of dust mask users was associated with reasons why they had started individual respiratory protection. The subjects were recontacted in order to identify those who started using a mask to deliberately prevent symptoms (42 men) and those who started protection because of pre-existing respiratory symptoms (44 men). Not unexpectedly, between-group comparisons of respiratory symptoms and lung function suggest that swine producers who wear dust masks for preventive purposes have better respiratory health than those who wear dust masks because of symptoms or those who do not use individual respiratory protection. The individual reasons for starting dust mask usage should be examined among potential determinants of the outcomes of prospective studies which can then provide more valid assessment of the effect of individual respiratory protection.

Respiratory health of swine producers. Focus on young workers.

In this report, we compare the respiratory health of swine producers, grain farmers, and nonfarming control subjects, separately in all age groups and in young subjects. We examined 249 swine producers (age 37.7 years), 251 grain farmers (age 44.7 years), and 263 nonfarming subjects (age 40.7 years). Swine producers had significantly more symptoms of chronic bronchitis (15.3 percent) than did grain farmers (7.2 percent) or nonfarming men (5.7 percent). After controlling for age, height, and smoking, the functional indices of airflow (FEV1, FEV1/FVC, FEF25-75, Vmax50, and Vmax25) were slightly but significantly lower in swine producers than in grain farmers. In comparison with nonfarming subjects, swine producers also had significantly lower FEV1/FVC, FEF25-75, and Vmax50. Respiratory symptoms were associated with the number of hours of work per day. This indirect index of exposure was also inversely associated with FVC (p < 0.01) and FEV1 (p = 0.06), after adjustment for age, height, smoking, and dust mask usage. A relative excess of respiratory symptoms and lower lung function variables were found in swine producers aged 26 to 35 years. Also in this age group, a multivariate analysis revealed statistically significant effects of daily duration of work on FVC and FEV1. The results confirm that working in swine confinement units is a risk factor for chronic respiratory symptoms and minor lung function changes. An increased risk in young workers may reflect more intense occupational exposure in this subgroup of swine producers.

Environment, respiratory disease, and performance of pigs in three Saskatchewan grower-finisher barns.

A microcomputer-based environmental monitoring system was used to monitor temperature, humidity, and ventilation rate continuously in three commercial grower-finisher swine barns in Saskatchewan. During the monitoring period, a group of pigs in each barn was examined for growth rate, amount of lung affected with pneumonia, and degree of atrophic rhinitis. In addition, the total bacterial colony forming particle count within the airspace of each barn was measured once each week.Significant differences existed among barns for daily maximum and minimum temperature, relative humidity, ventilation rate, and average bacterial colony forming particle counts. There was no difference among farms in the average percentage of lung affected with pneumonia, average snout atrophy score, or growth rate of the test animals.On one farm, there was a significant positive correlation between snout score and percentage of lung affected with pneumonia. On another farm, there was a significant negative correlation between percentage of lung affected with pneumonia and growth rate.