Characteristics of the study population, Beijing Yanshan Petrochemical Corporation, China
|
No exposure (n=438) mean (SD) |
Exposure to benzene (n=354) mean (SD) | |
| Age (y) | 27.0 (2.4) | 26.7 (1.9) |
| Duration of employment (y) | 5.7 (3.0) | 6.3 (2.7) |
| Weight before pregnancy (kg) | 57.8 (9.3) | 58.3 (9.7) |
| Height before pregnancy (cm) | 161.5 (5.0) | 161.0 (4.7) |
| BMI before pregnancy (kg/m2 ) | 22.2 (3.5) | 22.5 (3.6) |
| Birth weight (g) | 3464 (429) | 3382 (451) |
| Gestational age (weeks) | 40.0 (1.3) | 39.8 (1.5) |
| n (%) | n (%) | |
| Age (y): | ||
| 20–25 | 94 (21.5) | 70 (19.8) |
| 26–29 | 276 (63.0) | 250 (70.6) |
| 30–40 | 68 (15.5) | 34 (9.6) |
| Education: | ||
| Middle school or lower | 45 (10.3) | 33 (9.3) |
| High school | 217 (49.5) | 247 (69.8) |
| College or above | 176 (40.2) | 74 (20.9) |
| Passive smoking at home or work | 239 (55.6) | 218 (61.8) |
| Parity (one or more) | 18 (4.1) | 14 (4.0) |
| Female baby | 215 (49.1) | 171 (48.7) |
| Work stress | 85 (19.4) | 57 (16.1) |
| Noise | 56 (13.0) | 151 (42.8) |
| Physical exertion | 105 (24.0) | 89 (25.1) |
| Other hazards | 22 (5.0) | 86 (24.3) |
| Work mainly in a sitting posture | 250 (57.1) | 245 (69.2) |