Table 2.
Demographics of ABCD participants with hair toxicology tests, and those with positive and negative hair test results indicating substance exposure.
| Hair toxicology subsample | Confirmed positive via hair | Confirmed negative via hair | Significant difference by confirmed result | |
|---|---|---|---|---|
| (n = 696) | (n = 116) | (n = 580) | ||
| Age (years; range: 9–13) | 10.65 years (SD = 1.02) |
10.8 (SD = 1.00) |
10.62 (SD = 1.02) |
– |
| Female | 47.1% | 37.1% | 49.1% | p = 0.02 |
| Parents married | 63.1% | 45.7% | 66.6% | p < 0.001 |
| Race/ethnicity | p < 0.001 | |||
| Asian | 0.7% | 0% | 0.8% | |
| Black | 5.3% | 12.9% | 3.8% | |
| Hispanic | 17.8% | 17.2% | 17.9% | |
| White | 64.4% | 54.3% | 66.4% | |
| Other/multiple | 11.8% | 16.4% | 11.0% | |
| Parent education | p < 0.001 | |||
| Less than high school diploma | 3.1% | 6.9% | 2.4% | |
| High school/GED | 7.6% | 13.8% | 6.4% | |
| Some college | 29.0% | 43.1% | 26.2% | |
| Bachelor’s degree | 27.3% | 12.1% | 30.3% | |
| Post graduate degree | 32.9% | 24.1% | 34.7% | |
| Yearly household income | p < 0.001 | |||
| <$50,000 | 26.0% | 44.8% | 22.2% | |
| ≧$50,000 and <$100,000 | 27.4% | 20.7% | 28.8% | |
| ≧$100,000 | 40.2% | 27.6% | 42.7% | |
| Time point | – | |||
| Baseline | 61.4% | 56.0% | 62.2% | |
| Year 1 follow-up | 16.9% | 21.5% | 16.0% | |
| Year 2 follow-up | 21.8% | 22.4% | 21.7% |
Notes: If a significant difference (p < 0.05) was found for those with positive and negative hair tests, the p value is listed; sum totals of categories which are less than 100% are due to participants reporting “Don’t Know” or “Refuse to Answer”; sample size is calculated from the total number of hair samples assayed, with participants whose hair was assayed at two time points counted individually.