The summary-effect estimate for low exposure was 1.83 (95% CI 0.75-4.48), for medium exposure 1.67 (0.86-3.24), and for high exposure 3.50 (0.90-13.2), the latter was based on only one study available.
b AFB1-exposure years were: < 40 years for short exposure; 40 - 48 years for medium exposure; > 48 years for long exposure.
In the adjusted analysis, the associations were strengthened with the medium exposure category estimate for FEV1 becoming statistically significant, and the dose response trend significant for FEV1 and near-significant for FVC (table 2).
When workers were categorized in tertiles according to estimated TCDD exposure, SMRs were 0.8 (0.1–2.9) for low exposure (<0.7 ppt-years; 2 deaths), 0.6 (0.1–2.4) for medium exposure (0.7 3.99 ppt-years; 2 deaths), and 1.4 (0.4 3.6) for high exposure (≥4.0 ppt-years; 4 deaths).
For FVC, there was a significant negative association for the medium exposure category and a significant dose response trend; for FEV1, the dose response trend did not reach statistical significance (table 4).
Interestingly, the effect estimate for medium exposure was very near the reference (figure 1).
The miR-146b level increased by 12.9-fold within 48 h of differentiation medium exposure and remained high for the remainder of the differentiation time course.
This focus on short to medium exposure may be appropriate for pneumonia which is generally an acute condition, though often associated with chronic underlying lung disease.
Following additional adjustment for age at baseline, odds ratios remained elevated for both exposure groups (OR = 1.09; 95 % CI = 0.88-1.36 for the medium exposure group and OR = 1.40; 95 % CI: 1.01-1.94 for the high exposure group).
Additionally, there was a remarkably consistent indication of a possible dose response effect when comparing risk estimates for the medium exposure category to the high.
