Table 2.
Distribution of DNA methylation at baseline by categories of covariates.
| Methylation (mean ± SD) |
|||
|---|---|---|---|
| Variable | n (%) | Alu (%) | LINE-1 (%) |
| Tibia lead (g/g)a | |||
| 13.0 | 166 (32.1) | 26.40 ± 0.95 | 77.01 ± 1.79 |
| > 13.0 to 22 | 176 (34.0) | 26.18 ± 1.02 | 76.64 ± 2.02 |
| > 22 | 175 (33.9) | 26.32 ±1.04 | 76.73 ± 1.74 |
| p for trend | 0.50 | 0.18 | |
| Patella lead (g/g)a | |||
| 17.0 | 167 (32.9) | 26.36 ± 1.03 | 77.17 ± 1.79 |
| > 17.0 to 29 | 160 (31.5) | 26.30 ± 0.91 | 76.61 ± 1.94 |
| > 29 | 181 (35.6) | 26.22 ± 1.07 | 76.57 ± 1.80 |
| p for trend | 0.19 | 0.003 | |
| Blood lead (g/dL)a | |||
| 2.0 | 114 (24.6) | 26.35 ± 0.85 | 76.97 ± 1.78 |
| > 2.0 to 4.0 | 205 (44.3) | 26.18 ± 0.95 | 76.68 ± 2.06 |
| > 4.0 | 144 (31.1) | 26.41 ± 1.16 | 76.78 ± 1.61 |
| p for trend | 0.52 | 0.44 | |
| Lymphocytes (%)a | |||
| 21.0 | 165 (31.9) | 26.26 ± 0.95 | 77.03 ± 1.88 |
| > 21.0 to 28 | 186 (36.0) | 26.39 ± 1.08 | 76.69 ± 1.64 |
| > 28 | 166 (32.1) | 26.23 ± 0.98 | 76.66 ± 2.05 |
| p for trend | 0.79 | 0.07 | |
| Age (years) | |||
| < 70 | 186 (36.0) | 26.41 ± 0.97 | 77.05 ± 2.01 |
| 70–79 | 265 (51.3) | 26.28 ± 1.03 | 76.64 ± 1.80 |
| > 80 | 66 (12.8) | 26.07 ± 1.01 | 76.65 ± 1.54 |
| p for trend | 0.02 | 0.04 | |
| BMI (kg/m2) | |||
| < 25 | 97 (18.8) | 26.22 ± 0.98 | 76.74 ± 1.89 |
| 25–30 | 290 (56.1) | 26.28 ± 0.94 | 76.72 ± 1.85 |
| > 30 | 130 (25.1) | 26.39 ± 1.16 | 76.97 ± 1.85 |
| p for trend | 0.21 | 0.31 | |
| Education | |||
| Less than high school | 46 (9.2) | 26.28 ± 1.05 | 76.07 ± 1.79 |
| High school/some college | 314 (62.4) | 26.25 ± 0.97 | 76.85 ± 1.84 |
| Four years of college | 143 (28.4) | 26.40 ± 1.09 | 76.88 ± 1.88 |
| p for trend | 0.25 | 0.06 | |
| Cigarette smoking (pack-years) | |||
| 0 | 174 (33.7) | 26.22 ± 0.99 | 76.67 ± 1.58 |
| 30 | 206 (39.8) | 26.40 ± 1.09 | 76.71 ± 1.99 |
| > 30 | 137 (26.5) | 26.25 ± 0.89 | 77.05 ± 1.96 |
| p for trend | 0.68 | 0.09 | |
a
Categories are based on the tertile of the variable.