Table 1.
Quantile of county-level community water system (CWS) arsenic concentrations (μg/L) and high probabilitya of private well water arsenic (wAs) >10 μg/L by county characteristics (N = 2231), (2006-2011). SES = socioeconomic status.
| N | CWS arsenic (μg/L) | High probability (%) private well arsenic >10 μg/L |
||||||
|---|---|---|---|---|---|---|---|---|
| Continuous probability |
≤5 |
>15–30 |
>30–50 |
>50 |
||||
| 50% (75% 95%) | 50% (75% 95%) | % Counties by row | ||||||
| Nationwide, 2006–2011 | 2231 | 0.6 (1.5, 6.0) | 5 (10, 35) | 53 | 31 | 10 | 4 | 3 |
| Regionb | ||||||||
| Central Midwest | 351 | 1.4 (4.0, 8.2) | 5 (7, 18) | 55 | 36 | 9 | – | – |
| Eastern Midwest | 395 | 0.7 (1.6, 4.7) | 9 (19, 51) | 32 | 37 | 16 | 10 | 5 |
| Mid-Atlantic | 160 | 0.4 (0.6, 1.6) | 7 (10,21) | 35 | 56 | 8 | 2 | – |
| New England | 53 | 0.6 (0.9, 2.3) | 13 (28, 60) | 8 | 45 | 26 | 9 | 11 |
| Pacific Northwest | 189 | 0.9 (2.2, 5.2) | 10 (15, 39) | 11 | 63 | 16 | 7 | 3 |
| Southeast | 795 | 0.4 (0.5, 1.2) | 3 (4, 8) | 85 | 14 | 1 | 0 | – |
| Southwest | 288 | 2.1 (4.5, 11) | 9 (22, 62) | 36 | 27 | 21 | 7 | 9 |
| Sociodemographic clusterc | ||||||||
| Mostly Rural, Mid SES | 742 | 0.4 (0.7, 3.8) | 3 (6, 25) | 67 | 23 | 6 | 2 | 1 |
| Rural, American Indian | 21 | 2.8 (4.2, 6.3) | 9 (13, 19) | 24 | 62 | 14 | – | – |
| Rural, Mid/Low SES | 80 | 0.4 (0.7, 5.8) | 3 (4, 26) | 78 | 15 | 5 | – | 3 |
| Rural, High SES | 484 | 1.2 (3.2, 7.1) | 6 (12, 41) | 38 | 42 | 12 | 5 | 4 |
| Semi Urban, Hispanic | 158 | 2.3 (5.1, 11) | 10 (24, 63) | 28 | 30 | 20 | 11 | 11 |
| Semi Urban, Mid/Low SES | 158 | 0.4 (0.4, 1.3) | 2 (3, 6) | 91 | 9 | – | – | – |
| Semi Urban, High SES | 553 | 0.6 (1.1, 4.5) | 7 (12, 32) | 40 | 40 | 13 | 4 | 2 |
| Young Urban Mid/High SES | 24 | 1.7 (2.4, 4.4) | 10 (20, 26) | 29 | 29 | 38 | 4 | – |
| % served by CWSd | ||||||||
| ≤10% | 8 | 0.4 (0.7, 1.8) | 2 (3, 14) | 88 | – | 13 | – | – |
| >10 to 30% | 102 | 0.8 (2.4, 6.8) | 4 (8, 32) | 63 | 24 | 8 | 3 | 3 |
| >30 to 50% | 284 | 0.5 (0.9, 5.1) | 4 (10, 37) | 54 | 32 | 8 | 5 | 2 |
| >50% | 1832 | 0.6 (1.6, 6.0) | 5 (10, 34) | 52 | 31 | 10 | 3 | 3 |
a
90th percentile probability of private well water arsenic.
b
Region groupings: Central Midwest (ND, SD, NE, KS, MO), Eastern Midwest (WI, IL, IN, MI, OH, MN, IA), Mid-Atlantic (PA, MD, DC, DE, NY, NJ, CT, RI), New England (MA, VT, NH, ME), Pacific Northwest (WA, OR, MT, WY, and ID), Southeast (OK, AR, LA, MS, AL, FL, GA, TN, KY, SC, NC, VA, WV), Southwest (CA, NV, UT, CO, AZ, NM, TX).
d
Maupin et al. (2014). 2010 water use estimates used to determine percent of county population served by public water systems.