Table 2.
Main baseline characteristics of the study population according to quartiles of estimated dietary dioxin exposure, E3N cohort, 1993 (n = 63,830)
| Dietary dioxin exposure (pg/kg body weight/day) | ||||
|---|---|---|---|---|
| <0.98 | [0.98, 1.23] | [1.23, 1.52] | ≥1.52 | |
| Age (years), mean ± SD | 53.5 ± 6.8 | 53.0 ± 6.7 | 52.5 ± 6.5 | 51.9 ± 6.3 |
| Energy intake (kcal/day), mean ± SD | 1710.3 ± 391.7 | 2003.6 ± 405.5 | 2231.6 ± 437.0 | 2580.8 ± 513.4 |
| Smoking status, n (%) | ||||
| Non-smoker | 8672 (54.3) | 8611 (54.0) | 8614 (54.0) | 8429 (52.8) |
| Former smoker | 5102 (32.0) | 5259 (33.0) | 5243 (32.9) | 5288 (33.1) |
| Smoker | 2184 (13.7) | 2087 (13.1) | 2101 (13.2) | 2240 (14.0) |
| Combined menopausal status, MHT a use and BMI b , n (%) | ||||
| Premenopausal | ||||
| BMI <25 kg/m2 | 4797 (73.7) | 5665 (82.2) | 6362 (87.1) | 7143 (91.5) |
| BMI ≥25 kg/m2 | 1715 (26.3) | 1227 (17.8) | 942 (12.9) | 667 (8.5) |
| Postmenopausal not using MHT | ||||
| BMI <25 kg/m2 | 2572 (58.7) | 2679 (70.4) | 2715 (76.5) | 2692 (82.8) |
| BMI ≥25 kg/m2 | 1813 (41.4) | 1129 (29.7) | 833 (23.5) | 560 (17.2) |
| Postmenopausal using MHT | ||||
| BMI <25 kg/m2 | 3526 (69.7) | 4127 (78.5) | 7261 (83.5) | 4344 (88.7) |
| BMI ≥25 kg/m2 | 1535 (30.3) | 1130 (21.5) | 845 (16.6) | 551 (11.3) |
| Parity and age at first birth, n (%) | ||||
| No child | 2035 (12.8) | 1890 (11.8) | 1793 (11.2) | 1685 (10.6) |
| ≤2 children <30 years old | 7661 (48.0) | 7913 (49.6) | 8076 (50.6) | 8393 (52.6) |
| ≤2 children ≥30 years old | 1527 (9.6) | 1402 (8.8) | 1464 (9.2) | 1378 (8.6) |
| ≥3 children | 4735 (29.7) | 4752 (29.8) | 4625 (29.0) | 4501 (28.2) |
| Breastfeeding, n (%) | ||||
| Ever | 8916 (55.9) | 9234 (55.9) | 9321 (58.4) | 9365 (58.7) |
| Never | 7042 (44.1) | 6723 (42.1) | 6637 (41.6) | 6592 (41.3) |
| Alcohol intake, n (%) | ||||
| 0 g/day | 2636 (16.5) | 2021 (12.7) | 1685 (10.6) | 1356 (8.5) |
| <6.9 g/day | 6688 (41.9) | 6354 (39.8) | 5897 (37.0) | 5181 (32.5) |
| ≥6.9 g/day | 6634 (41.6) | 7582 (47.5) | 8376 (52.5) | 9420 (59.0) |
| Personal history of benign breast disease, n (%) | ||||
| Yes | 4292 (26.9) | 4570 (28.6) | 4907 (30.8) | 4949 (31.0) |
| No | 11666 (73.1) | 11387 (71.4) | 11051 (69.3) | 11008 (69.0) |
aMHT, menopausal hormone treatment; bBMI, body mass index.