Description of atrazine levels in the water distribution units (UDIs) included in the study, by size of population supplied
| Population supplied | No. UDI | No. atrazine measurements | No. <DL | No. >0.1 μg/l | Geom. mean atrazine level (excluding <DL) | Geom. mean atrazine level (including <DL) |
|---|---|---|---|---|---|---|
| DL, detection limit. | ||||||
| Raw water | ||||||
| <4000 | 85 | 664 | 394 (59%) | 119 (18%) | 0.091 | 0.027 |
| 4000–20000 | 20 | 495 | 204 (41%) | 118 (24%) | 0.092 | 0.040 |
| >20000 | 6 | 589 | 206 (35%) | 178 (30%) | 0.098 | 0.047 |
| Missing | 1 | |||||
| Overall | 112 | 1748 | 804 (46%) | 415 (24%) | 0.094 | 0.036 |
| May to September | 916 | 347 (38%) | 312 (34%) | 0.122 | 0.052 | |
| October to April | 832 | 457 (55%) | 103 (12%) | 0.063 | 0.025 | |
| Treated water | ||||||
| <4000 | 85 | 235 | 140 (60%) | 37 (16%) | 0.079 | 0.024 |
| 4000–20000 | 20 | 285 | 168 (59%) | 43 (15%) | 0.077 | 0.025 |
| >20000 | 6 | 393 | 219 (56%) | 40 (10%) | 0.065 | 0.023 |
| Missing | 1 | |||||
| Overall | 112 | 913 | 527 (58%) | 120 (13%) | 0.071 | 0.024 |
| May to September | 520 | 235 (45%) | 103 (20%) | 0.081 | 0.033 | |
| October to April | 393 | 292 (74%) | 17 (4%) | 0.049 | 0.015 | |