Town

(n)

Size of sample

(n)

Mean arsenic

(µg/l ± SD)

Mean mercury

(µg/l ± SD)

Bacanuchi

9

3.6 ± 5.5

2.2 ± 0.2

Arizpe

10

3.1 ± 0.8*

2.6 ± 1.9

Aconchi

10

5.1 ± 1.3

2.1 ± 0.3

Baviácora

10

5.8 ± 3.7

2.0 ± 0.08

Ures

10

5.6 ± 3.9

1.9 ± 0.1