| Study groups | N | Mean | Std. Error Mean | P value |
age in years | Subjects | 190 | 34.78 | 0.73 | 0.385 |
Controls | 80 | 35.95 | 1.13 | ||
duration of occupation (years) | Subjects | 190 | 11.92 | 0.67 | 0.001 |
Controls | 80 | 8.04 | 0.82 | ||
body mass index (kg/m2) | Subjects | 190 | 24.92 | 0.26 | 0.028 |
controls | 80 | 26.14 | 0.571 | ||
mean systolic blood pressure (mmHg) | subjects | 190 | 118.49 | 1.06 | 0.008 |
controls | 80 | 113.62 | 1.26 | ||
mean diastolic blood pressure (mmHg) | subjects | 190 | 74.67 | 0.79 | 0.285 |
controls | 80 | 73.24 | 0.82 | ||
blood lead levels (ug/dl) | subjects | 190 | 50.38 | 1.78 | 0.003 |
controls | 80 | 40.48 | 2.83 |