Table 1.
Baseline characteristics of the study population by quintiles of toenail arsenic levels, the CARDIA study, 1987 to 2015 (n=4,102)a
| Characteristics | Total | Quintiles of toenail arsenic levels |
P value * |
||||
|---|---|---|---|---|---|---|---|
| 1 (lowest) | 2 | 3 | 4 | 5 (highest) |
|||
| No. of participants | 4,102 | 821 | 819 | 820 | 822 | 820 | |
| Toenail arsenic, ppm | 0.097 (0.065–0.150) | 0.047 (0.038–0.054) | 0.071 (0.065–0.077) | 0.097 (0.089–0.105) | 0.135 (0.122–0.150) | 0.237 (0.195–0.341) | NA |
| Toenail cadmium, ppm | 0.009 (0.004–0.019) | 0.006 (0.004–0.014) | 0.007 (0.004–0.015) | 0.009 (0.004–0.019) | 0.009 (0.005–0.020) | 0.011 (0.006–0.028) | <0.0001 |
| Toenail mercury, ppm | 0.215 (0.125–0.375) | 0.186 (0.108–0.317) | 0.220 (0.130–0.374) | 0.233 (0.131–0.404) | 0.232 (0.131–0.387) | 0.211 (0.126–0.371) | <0.0001 |
| Toenail mass, g | 0.024±0.013 | 0.022±0.012 | 0.023±0.013 | 0.025±0.014 | 0.026±0.014 | 0.025±0.014 | <0.0001 |
| Age, year | 27.0±3.6 | 27.0±3.8 | 27.3±3.5 | 27.1±3.6 | 26.8±3.5 | 26.7±3.6 | <0.01 |
| Female, % | 54.8 | 69.3 | 59.2 | 53.2 | 50.4 | 41.7 | <0.0001 |
| African-American, % | 47.8 | 61.0 | 49.5 | 45.0 | 42.3 | 41.0 | <0.0001 |
| Education, year | 14.2±2.4 | 14.3±2.2 | 14.3±2.3 | 14.4±2.4 | 14.0±2.4 | 14.0±2.4 | <0.01 |
| Current smoker, % | 20.5 | 13.7 | 17.4 | 18.4 | 25.2 | 28.0 | <0.0001 |
| Alcohol, g/day | 5.1 (0.0–15.6) | 0.0 (0.0–6.8) | 3.0 (0.0–11.2) | 5.4 (0.0–16.2) | 8.1 (0.0–22.0) | 9.5 (0.0–24.3) | <0.0001 |
| Physical activity score exercise units | 319 (168–533) | 248 (120–445) | 306 (178–513) | 332 (163–535) | 348 (196–573) | 365 (196–599) | <0.0001 |
| BMI, kg/m2 | 25.2±5.3 | 26.1±6.2 | 25.4±5.8 | 25.1±5.2 | 24.8±4.9 | 24.5±4.4 | <0.0001 |
| Waist circumference, cm | 79.7±12.1 | 80.6±13.9 | 79.6±12.2 | 79.6±11.8 | 79.4±11.5 | 79.5±10.7 | 0.27 |
| SBP, mmHg | 107.8±10.7 | 107.2±10.8 | 106.7±10.4 | 107.6±10.3 | 108.1±11.3 | 109.4±10.7 | <0.0001 |
| DBP, mmHg | 67.5±9.5 | 67.7±9.5 | 67.3±9.5 | 67.1±9.4 | 67.1±9.4 | 68.3±9.8 | 0.03 |
| Total cholesterol, mg/dL | 182.7±34.5 | 184.0±33.3 | 183.1±33.7 | 184.4±34.6 | 181.8±34.1 | 180.2±36.5 | 0.08 |
| Triglycerides, mg/dL | 77.4±48.5 | 73.8±41.2 | 76.0±45.4 | 77.3±51.7 | 78.9±49.6 | 81.0±53.3 | 0.03 |
| HDL cholesterol, mg/dL | 54.7±13.9 | 54.0±13.1 | 54.3±13.5 | 55.2±14.1 | 55.1±14.3 | 54.6±14.6 | 0.34 |
| LDL cholesterol, mg/dL | 112.7±32.7 | 115.3±31.7 | 113.7±32.0 | 114.0±32.1 | 111.0±32.6 | 109.6±35.0 | <0.01 |
| Glucose, mg/dL | 82.1±12.1 | 81.3±10.4 | 81.6±14.4 | 81.8±8.7 | 83.4±16.0 | 82.4±8.7 | <0.01 |
| Family history of diabetes, % | 13.5 | 16.1 | 11.6 | 15.4 | 12.4 | 12.1 | 0.02 |
| Dietary intake | |||||||
| Magnesium, mg/day | 387.2±196.5 | 332.9±160.5 | 366.3±190.0 | 396.5±195.0 | 414.3±211.7 | 426.6±215.3 | <0.0001 |
| LCω3PUFA, g/day | 0.12±0.18 | 0.10±0.12 | 0.12±0.24 | 0.12±0.18 | 0.12±0.17 | 0.11±0.15 | 0.06 |
Abbreviations: BMI, body mass index; CARDIA, Coronary Artery Risk Development in Young Adults; HDL, high-density lipoprotein; DBP, diastolic blood pressure; IQR, inter-quartile range; LCω3PUFAs, long-chain omega-3 polyunsaturated fatty acids; LDL, low-density lipoprotein; NA, not applicable; SBP, systolic blood pressure; SD, standard deviation.
a
Data are means ±SDs, medians (IQRs), or proportions, unless otherwise specified.
*
P-values were for difference across quintiles of toenail arsenic levels using analysis of variance, chi-squared test, or Kruskal-Wallis equality-of-populations rank test.