Concentration of arsenic, cadmium, lead and uranium in water
in the endemic area ( n = 222) and non-endemic area ( n = 12). End canal = endemic area canal; End drink = endemic area drinking water; End reser = endemic area reservoir; End spring = endemic area spring; nonend drink = non-endemic area drinking water. Horizontal lines within the boxes represent the median values. The ends of the solid lines extending on either side of the boxes represent the minimum and the maximum. The dark dots are outliers; defined as being more than 1.5 interquartile ranges away from the box. The interquartile range is the distance between the upper part of the box and the lower part of the box. a Reference limits: arsenic <10 μg /l, cadmium <3 μg/l, lead <10 μg/l, uranium <2 μg/l .