RESUMEN
Excess lead in drinking water is a neglected source of lead toxicity in Pakistan. A cross-sectional survey in 2007/08 was made of water samples from drinking water sources in Karachi, a large industrial city. This study aimed to compare lead levels between untreated ground water and treated surface [tap] water in 18 different districts. Of 216 ground and surface water samples collected, 86% had lead levels higher than the World Health Organization maximum acceptable concentration of 10 ppb. Mean lead concentration in ground water [146 [SD 119] ppb] was significantly higher than in surface water [77.1 [SD 54] ppb]. None of the 18 districts had a mean lead level of ground or surface water below the WHO cut-off and ground water sources in 9 districts had a severe level of contamination [> 150 ppb]. Urgent action is needed to eliminate sources of contamination