Table 4.
Association Between Cumulative Maternal Occupational Exposure to Polycyclic Aromatic Hydrocarbons and the Risk of Any Oral Clefts in Offspring, National Birth Defects Prevention Study, 1997–2002.
| Cumulative Exposure Level (ug/m3–hours)A | Controls n | Cleft Lip With or Without Cleft Palate | Cases n | Cleft Palate OR (95% CI) | ||
|---|---|---|---|---|---|---|
| Cases n | OR (95% CI) | |||||
| Crude Analysis | ptrend = 0.01 | ptrend = 0.55 | ||||
| No PAH exposure | 0 | 2883 | 758 | 1.00 (ref) | 419 | 1.00 (ref) |
| Low PAH exposure | 0.32–100 | 55 | 21 | 1.45 (0.87, 2.42) | 11 | 1.38 (0.71, 2.65) |
| High PAH exposure | 108–6900 | 51 | 26 | 1.94 (1.20, 3.13) | 9 | 1.21 (0.59, 2.48) |
| Adjusted AnalysisB | ptrend = 0.02 | ptrend = 0.47 | ||||
| No PAH exposure | 0 | 2881 | 757 | 1.00 (ref) | 419 | 1.00 (ref) |
| Low PAH exposure | 0.32–100 | 55 | 21 | 1.36 (0.82, 2.27) | 11 | 1.33 (0.69, 2.56) |
| High PAH exposure | 108–6900 | 51 | 26 | 1.66 (1.02, 2.70) | 9 | 1.15 (0.56, 2.36) |
A
Cumulative exposure (unit-hours) was estimated by:(weighted intensity (unit)) x ((self reported work frequency (hours/week))/(7 days/week)) x (number of days worked one month before pregnancy through the third month of pregnancy), reported to two significant figures.
B
Cleft lip with or without cleft palate adjusted for maternal education. Cleft palate adjusted for maternal secondhand smoke exposure at home.