Table 1.
Demographic characteristics of participants [mean ± SD or n (%) unless otherwise indicated] (total n = 1,001).
| Characteristic | Value |
|---|---|
| Age (years) | 9.05±0.70 |
| Female | 474 (47.4) |
| Region | |
| Urban | 434 (43.4) |
| Industrial | 394 (39.4) |
| Rural | 173 (17.3) |
| Paternal education | |
| Years | 13.75±2.20 |
| Missing (n) | 82 |
| Yearly income | |
| > $25,000 | 576 (62.1) |
| ≤ $25,000 | 352 (37.9) |
| Missing (n) | 73 |
| IQ | |
| Verbal | 22.99±5.38 |
| Performance | 23.41±5.30 |
| Full-Scale | 110.07±14.46 |
| Missing (n) | 2 |
| ADHD-RS, parent-rated | |
| Inattention | 5.31±4.91 |
| Hyperactivity/impulsivity | 3.52±3.96 |
| Total | 8.84±8.34 |
| Missing (n) | 66 |
| ADHD-RS, teacher-rated | |
| Inattention | 5.08±6.53 |
| Hyperactivity/impulsivity | 3.61±5.46 |
| Total | 8.68±11.41 |
| Missing (n) | 59 |
| CPT | |
| Omission errors | 61.13±25.00 |
| Commission errors | 71.57±28.23 |
| Response time | 46.72±12.67 |
| Response time variability | 68.04±35.10 |
| Missing (n) | 2 |
| Environmental chemical concentrations [geometric mean(GSD)]a | |
| Mercury (μg/L) | 2.44(1.52) |
| Manganese (μg/L) | 13.82(1.35) |
| Cotinine (μg/g Cr) | 1.87(3.52) |
| MnBP (μg/g Cr) | 51.66(1.85) |
| MEOHP + MEHP (μg/g Cr) | 44.71(1.95) |
| BPA (μg/g Cr) | 1.32(2.33) |
| Lead (μg/dL) | 1.80(1.40) |
| Abbreviations: ADHD-RS, attention-deficit/hyperactivity disorder rating scale; CPT, Continuous Performance Test; Cr, creatinine; GSD, geometric standard deviation; MEHP, mono-2-ethylhexyl phthalate; MEOHP, mono-2-ethyl-5-oxohexyl phthalate; MnBP, mono-n-butyl phthalate. aNumbers of missing observations for environmental chemicals: cotinine n=12, MnBP n=7, MEOHP + MEHP n=7, BPA n=7. | |