Table 1 Median (10th–90th) values of As levels in groundwater (tap water) and commercially purified water (bottled water) samples collected in 2005–2007 and 2015–2017 surveys, along with existing historical dataset (1960s–2000) samples from wells located in municipalities of the La Comarca Lagunera province (north Mexico). Units µg L⁻¹.

Durango

 Gomez Palacio

Tap water

250

33.1 (1–532)^c

5

15.3 (8.2–36.8)^b

7

31.9 (7.9–101.3)^c

 Lerdo city

Tap water

189

34.3 (1–400)^c

18

19.0 (1.0–47)^b

19

21.0 (0.9–51.6)^b

Bottled water

Non-available data

30

19.4 (7.1–29.5)^b

30

16.8 (0.5–40.0)^b

Tlahualilo

Tap water

199

131.6 (1–770)^d,e

3

24.4 (12.5–35)^b,c

8

81.1 ± 27.7 (35.1–123.0)^d

Francisco I Madero

Tap water

331

126 (1–880)^d,e

26

40.6 (1.0–206.0)^c

31

83.0 (8.2–218.3)^c,d

*Nazas

Tap water

31

4.3 (nd to 15)^a

4

7.5 (2–15.1)

6

8.4 (6.5–10.2)^a

*Cuencame

Tap water

21

8.5 (nd to 47.1)^a,b

No samples collected

6

10.7 (1.3–17.7)^a,b

*Simon Bolivar

Tap water

16

 < 5 (nd to 5.0)

No samples collected

6

2.7 (0.1–7.7)^a

*Mapimi

Tap water

21

4.6 (nd to 10.0)^a

No samples collected

6

2.0 (0.05–9.2)^a

Non-CERHA

municipalities

Bottled water

Non-available data

No samples collected

14

7.0 (1.2–10.0)^a

Coahuila

 Matamoros

Tap water

168

62.9 (1.0–465.0)^d

6

29.9 (7.8–38.7)^c

13

38.0 (8.6–101.2)^c

 San Pedro

Tap water

324

117.2 (0.6–800.0)^d,e

17

172.9 (7.1–392.0)^e

23

67.2 (27.9–101.1)^d

Bottled water

Non-available data

11

42.2 (17.9–181.0)^c

60

39 (2–94.6)^c

 Torreon

Tap water

504

16.8 (0.3–258)^b

98

16.7 (3.1–52)^b

12

35.8 (19.7–51.9)^c

 Viesca

Tap water

79

67.2 (1.0–450.0)^d

No samples collected

4

62.5 (44.3–111.4)^d

Non-CERHA municipalities

Non-available data

14

3.5 (0.1–8.1)^a

11

4.3 (1.2–8.2)^a