Table 1. Demographic and exposure characteristics.
| Boys (n = 252) | Girls (n = 251) | |
| Mean (SD) age, years | 10.7 (1.5) | 10.7 (1.5) |
| Father’s education, n (%) | ||
| Primary or lower | 1 (0.55) | 3 (1.60) |
| Junior high school | 49 (26.78) | 37 (19.79) |
| Senior high school | 76 (41.53) | 85 (45.45) |
| College or university | 50 (27.32) | 59 (31.55) |
| Graduate education | 7 (3.83) | 3 (1.60) |
| Mother’s education, n (%) | ||
| Primary or lower | 4 (2.20) | 2 (1.07) |
| Junior high school | 43 (23.63) | 38 (20.32) |
| Senior high school | 71 (39.01) | 85 (45.45) |
| College or university | 59 (32.42) | 57 (30.48) |
| Graduate education | 5 (2.75) | 5 (2.67) |
| Mean (SD) height, cm | 146.1 (11.5) | 145.1 (10.9) |
| Mean (SD) weight, kga | 43.8 (14.3) | 39.2 (11.5) |
| Mean (SD) body fat composition, %a | 24.9 (9.2) | 17.7 (7.1) |
| Boy’s testicular volume, n (%) | ||
| <4 mL | 137 (54.37) | |
| 4–11 mL | 72 (28.57) | |
| 12–19 mL | 25 (9.92) | |
| ≥20 mL | 18 (7.14) | |
| Tanner stage of girls’ breast, n (%) | ||
| B1 | 55 (21.91) | |
| B2 | 74 (29.48) | |
| B3 | 64 (25.50) | |
| B4 | 46 (18.33) | |
| B5 | 12 (4.78) | |
| Tanner stage of pubic hair, n (%)b | ||
| PH1 | 219 (86.90) | 175 (69.72) |
| PH2 | 18 (7.14) | 27 (10.76) |
| PH3 | 12 (4.76) | 41 (16.33) |
| PH4 | 3 (1.19) | 7 (2.79) |
| PH5 | — | 1 (0.40) |
| Boy’s spermarche/girl’s menarche, n (%) | ||
| Yes | 8 (4.17) | 51 (25.89) |
| No | 184 (95.83) | 146 (74.11) |
| Urinary specific gravity-adjusted phthalate concentrations, µg/L, GM (95% CI)c | ||
| MBP | 28.57 (25.98, 31.41) | 19.60 (16.35, 23.50) |
| MMP* | 14.18 (12.83, 15.67) | 11.50 (10.28, 12.87) |
| MEP | 1.15 (0.93, 1.41) | 1.14 (0.91, 1.43) |
| MEHP | 1.65 (1.40, 1.94) | 1.65 (1.41, 1.92) |
| MEHHP | 16.10 (14.65, 17.68) | 14.5 (12.97, 16.22) |
| MEOHP* | 5.77 (5.25, 6.37) | 4.72 (4.18, 5.33) |
| ΣMEHP* | 24.49 (22.31, 26.89) | 21.52 (19.21, 24.11) |
CI, confidence interval; GM, geometric mean; MBP, monobutyl phthalate; MEHHP, mono-(2-ethyl-5-hydroxyhexyl) phthalate; MEHP, mono-(2-ethylhexyl) phthalate; MEOHP, mono-(2-ethyl-5-oxohexyl) phthalate; MEP, mono-ethyl phthalate; MMP, mono-methyl phthalate; ΣMEHP, sum of MEHP, MEHHP, and MEOHP concentrations.
aSignificant difference between boys and girls, P < 0.05, t test.
bSignificant difference between boys and girls, P < 0.05, Wilcoxon rank-sum test.
cValues based on test results for 247 boys and 248 girls.