Table 3.
Population/exposure | Nonexposed to endotoxin-related activitiesa | Exposed to endotoxin-related activitiesa | p for interactiond | ||
---|---|---|---|---|---|
Casesb (n) | RRc (95% CI) | Casesb(n) | RRc (95% CI) | ||
Farmers | |||||
Diesel tractors | |||||
No/lowe | 72 | 1.00 | 107 | 1.00 | 0.63 |
Intermediatef | 10 | 0.99 (0.50, 1.93) | 41 | 1.11 (0.77, 1.61) | |
Highg | 6 | 1.83 (0.79, 4.25) | 29 | 1.19 (0.78, 1.81) | |
Gasoline tractors | |||||
No/lowe | 82 | 1.00 | 155 | 1.00 | 0.33 |
Intermediatef/highg | 6 | 1.63 (0.71, 3.75) | 19 | 0.99 (0.61, 1.60) | |
Combines or other types of crop harvesters | |||||
0 day | 49 | 1.00 | 38 | 1.00 | 0.43 |
1–30 days | 33 | 1.38 (0.88, 2.17) | 113 | 0.94 (0.41, 2.18) | |
≥ 31 days | 6 | 0.80 (0.34, 1.89) | 24 | 0.72 (0.14, 3.76) | |
Trucks | |||||
No/lowe | 64 | 1.00 | 129 | 1.00 | 0.50 |
Intermediatef | 4 | 0.70 (0.25, 1.91) | 11 | 1.38 (0.74, 2.56) | |
Highg | 18 | 0.84 (0.49, 1.41) | 34 | 0.88 (0.59, 1.30) | |
Spouses | |||||
Diesel tractors | |||||
No/< monthly | 75 | 1.00 | 46 | 1.00 | 0.01 |
≥ Monthly | 19 | 1.24 (0.75, 2.07) | 15 | 0.41 (0.23, 0.73) | |
Gasoline tractors | |||||
No/< monthly | 82 | 1.00 | 46 | 1.00 | 0.16 |
≥ Monthly | 13 | 0.93 (0.52, 1.67) | 14 | 0.51 (0.28, 0.93) | |
Combines or other types of crop harvesters | |||||
0 day | 94 | 1.00 | 55 | 1.00 | 0.66 |
≥ 1 day | 5 | 0.87 (0.35, 2.13) | 7 | 0.66 (0.30, 1.45) | |
Trucks | |||||
No/< monthly | 72 | 1.00 | 36 | 1.00 | 0.78 |
≥ Monthly | 23 | 0.86 (0.53, 1.37) | 24 | 0.77 (0.46, 1.30) | |
aEndotoxin-related activities were defined by current exposure to animals or stored grain in farmers and exposure to farm animals in the year before enrollment in spouses. bCase counts do not sum to total counts because of missing values for exposure variables. cFor farmers: rate ratios were adjusted for age, cigarette pack-years (non-smokers, < 20, 20–39, 40–59, ≥ 60, missing), state, race, and level of education; for spouses: rate ratios were adjusted for age, pack-years (non-smokers, < 20, 20–39, ≥ 40, missing), and level of education. dp for interaction was obtained from the likelihood ratio test by adding cross-product terms between each category of exposure and the variable reflecting potential exposure to endotoxins. eNo or low exposure was defined by driving < daily in one season. fIntermediate exposure: daily driving in one season. gHigh exposure: daily driving in both seasons. |