Table 2.
Distributions of maternal exposures and infant outcomes.
| Percentiles | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| N | Mean ± SD | Min. | 5th | 25th | 50th | 75th | 95th | Max. | |
| Urine samples per mother, no. | 107 | 4 ± 3 | 1 | 1 | 2 | 3 | 6 | 10 | 12 |
| Average time between samples, days | 84 | 19.6 ± 15.5 | 6.0 | 7.0 | 11.2 | 15.8 | 19.8 | 53.5 | 105.0 |
| Time from last sample to birth, days | 107 | 10 ± 18 | 0 | 0 | 2 | 6 | 11 | 34 | 117 |
| Mean whole pregnancy concentrations, ng/µg | |||||||||
| Perchloratea | 107 | 4.4 ± 2.8 | 0.7 | 1.6 | 2.6 | 3.7 | 5.3 | 10.5 | 20.1 |
| Nitrate | 107 | 51,674 ± 21,356 | 2197 | 28,763 | 35,911 | 50,839 | 60,970 | 86,837 | 158,304 |
| Thiocyanate | 107 | 1484 ± 2004 | 124 | 202 | 479 | 967 | 1505 | 4551 | 14,769 |
| PECb | 107 | 4.8 ± 2.5 | 0.5 | 1.8 | 3.1 | 3.9 | 6.5 | 8.4 | 13.7 |
| Iodide | 107 | 190 ± 142 | 45 | 63 | 99 | 156 | 240 | 395 | 1097 |
| Mean 2nd trimester concentrations, ng/µg | |||||||||
| Perchlorate | 40 | 5.5 ± 9.9 | 0.8 | 1.4 | 2.5 | 3.3 | 4.4 | 12.5 | 64.4 |
| Nitrate | 40 | 52,675 ± 41,078 | 2197 | 23,389 | 35,699 | 45,865 | 55,235 | 89,310 | 279,618 |
| Thiocyanate | 40 | 1117 ± 1126 | 122 | 193 | 518 | 817 | 1156 | 4121 | 5533 |
| PEC | 40 | 5.6 ± 3.8 | 0.8 | 1.7 | 2.8 | 4.8 | 7.0 | 12.7 | 20.8 |
| Iodide | 40 | 166 ± 119 | 39 | 50 | 88 | 132 | 222 | 464 | 562 |
| Mean 3rd trimester concentrations, ng/µg | |||||||||
| Perchlorate | 104 | 4.5 ± 3.8 | 0.7 | 1.4 | 2.5 | 4.0 | 5.4 | 8.6 | 31.0 |
| Nitrate | 104 | 51,582 ± 20,659 | 4110 | 29,174 | 39,221 | 50,867 | 62,316 | 92,471 | 127,976 |
| Thiocyanate | 104 | 1528 ± 2124 | 83 | 202 | 474 | 940 | 1601 | 4501 | 14,769 |
| PEC | 104 | 4.8 ± 2.6 | 0.5 | 1.8 | 3.1 | 4.0 | 6.1 | 8.2 | 16.7 |
| Iodide | 104 | 194 ± 165 | 45 | 56 | 99 | 153 | 250 | 395 | 1425 |
| Last sample concentrations, ng/µg | |||||||||
| Perchlorate | 107 | 4.5 ± 5.5 | 0.7 | 1.2 | 2.4 | 3.4 | 5.2 | 9.1 | 54.1 |
| Nitrate | 107 | 51,244 ± 28,837 | 2197 | 26,379 | 32,511 | 43,507 | 60,970 | 103,971 | 184,943 |
| Thiocyanate | 107 | 1520 ± 2283 | 90 | 168 | 434 | 864 | 1619 | 5097 | 16,536 |
| PEC | 107 | 4.4 ± 2.8 | 0.5 | 1.3 | 2.4 | 3.9 | 5.7 | 9.4 | 16.7 |
| Iodide | 107 | 268 ± 791 | 42 | 47 | 91 | 149 | 251 | 395 | 8011 |
| Infant measures | |||||||||
| Gestational age, weeks | 107 | 37.6 ± 2.6 | 23 | 33 | 37 | 38 | 39 | 40 | 41 |
| Weight, grams | 107 | 3102 ± 747 | 670 | 1805 | 2625 | 3195 | 3665 | 4180 | 4985 |
| Length, cm | 107 | 48.4 ± 4.7 | 19.5 | 43.2 | 47.0 | 49.5 | 50.8 | 54.2 | 56.0 |
| Head circumference, cm | 105 | 33.0 ± 2.5 | 22.0 | 29.2 | 32.0 | 33.0 | 34.5 | 36.0 | 39.4 |
a
Perchlorate, thiocyanate, nitrate, and iodide concentrations are creatinine-adjusted (ng/µg creatinine);
b
PEC: perchlorate equivalence concentration (molar concentrations) = (perchlorate) + (nitrate/240) + (thiocyanate/15).