Overview of epidemiological studies indicating adverse respiratory effects related to environmental endotoxin exposure
| Reference | Population | N | Exposure* | Health effect |
|---|---|---|---|---|
| FEV1 = forced expiratory volume in 1 second; FVC = forced vital capacity; MEF25, MEF50, MEF75 = maximum expiratory flow rates at 25%, 50% and 75% of the vital capacity; MMEF = maximum mid expiratory flow; PEF = peak expiratory flow. | ||||
| *Exposure is expressed as the mean exposure (or range of (mean) exposures if no overall mean is given) in ng or endotoxin units per m3 or per mg of house dust; one endotoxin unit is approximately 0.1 ng (the exact conversion factor varies depending on the source of endotoxin for calibration). | ||||
| †Longitudinal study (all other studies were cross sectional studies) | ||||
| ‡Association between endotoxin exposure and PEF variability disappeared after adjusting for pets in the home. | ||||
| §15 year follow up of study by Kennedy et al in cotton mill workers. | ||||
| Occupational studies: | Acute respiratory effects: | |||
| 48 | Pig farm workers | 40 | 180 ng/m3 | Cross-shift decline in FEV1 and MEF25 |
| 49 | Slaughter house workers | 23 | 20–1500 ng/m3 | Cross-shift decline in FEV1 and FVC; increased prevalence of respiratory symptoms |
| 50 | Animal feed workers | 119 | 29 ng/m3 | Cross-shift decline in MMEF and MEF50; cross-week decline in FEV1, MEF25, MMEF and MEF50 |
| 51, 52 | Fibreglass workers | 130 | 0.4–759 ng/m3 | Cross-shift decline in PEF and FEV1; increased amplitude of PEF; increased prevalence of respiratory symptoms and symptoms of fever, joint pains, and influenza-like symptoms |
| 53 | Potato processing workers | 61 | 21–56 EU/m3 | Cross-shift decline in FEV1 and MMEF |
| 54 | Potato processing workers | 97 | 534 EU/m3 | Cross-shift decline in PEF; increased prevalence of respiratory symptoms |
| Chronic respiratory effects: | ||||
| 55 | Cotton mill workers | 443 | 2–550 ng/m3 | Decline in FEV1; increased prevalence of chronic bronchitis and byssinosis |
| 56 | Pig farm workers | 183 | 130 ng/m3 | Decline in FEV1 and FVC; increased prevalence of respiratory symptoms |
| 57 | Cotton mill workers | 253 | 9–126 ng/m3 | Decline in FEV1 and FVC; increased prevalence of respiratory symptoms |
| 58 | Animal feed workers | 315 | 25 ng/m3 | Decline in FEV1,, FVC, PEF, MEF75, MEF50 |
| 59 | Cotton mill workers | 34 | 20–320 ng/m3 | Increase in bronchial hyperresponsiveness |
| 60 | Pig farm workers | 54 | 11332 EU/ m3 | Decline in FEV1 and FVC; increased prevalence of cough and chronic bronchitis |
| 61 | Grain workers | 410 | 2859 EU/ m3 | Decline in FEV1; increased prevalence of respiratory symptoms |
| 62† | Farm workers (pig farms/others) | 168/127 | 588/410 EU/m3 | Longitudinal decline in FEV1 and MMEF |
| 63† | Pig farm workers | 171 | 105 ng/m3 | Longitudinal decline in FEV1 |
| 64† | Grain and animal feed workers | 140 | 3.6–99.0 ng/m3 | Longitudinal decline in FEV1 and MMEF |
| 65†§ | Cotton mill workers | 366 | ∼3200 EU/m3 | Longitudinal decline in FEV1 and FVC |
| Indoor studies: | ||||
| 20 | Adult asthmatic patients | 28 | 2.59 ng/mg | Decline in FEV1 and FEV1/FVC; increase in asthma medication and symptoms |
| 66 | Adult asthma (40)/rhinitis (29) patients | 69 | 1.78 ng/mg | Decline in FEV1, and FEV1/FVC; increase in asthma medication and symptoms |
| 67 | Children (50% with asthma) | 20 | 1–100 EU/mg | Increase in asthma medication and symptoms in asthmatic children |
| 22 | Children (50% with airway symptoms) | 148 | 24.9 EU/mg | Increased PEF variability in atopic children with asthma symptoms‡ |
| 68† | Infants | 499 | 100 EU/mg | Increased prevalence of wheeze during first year of life |