Chemistry

Sorting Out Lead Levels

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Science  20 Apr 2007:
Vol. 316, Issue 5823, pp. 341
DOI: 10.1126/science.316.5823.341a

The toxicity of lead has prompted significant concern over the presence of the heavy metal in various sources of drinking water. However, measuring the relatively low concentrations at issue can be an analytical challenge, particularly because of the need to avoid contamination of the vessels and apparatus. As a result, there have been conflicting reports of the lead concentrations measured in bottled waters.

Shotyk and Krachler have applied clean-room procedures and high-sensitivity detection technology—developed to gauge the nanogram-per-liter concentrations of lead present in polar ice—to the measurement of lead levels in a sample of 125 commercially available bottled waters from across the world. For comparison, they also assayed artesian flow sources in southern Ontario, Canada. In all cases, the measured concentrations were several orders of magnitude below the 10μg/liter level considered hazardous. However, glass bottles appeared to leach lead over time, with concentrations roughly doubling (from ~100 to ~200 ng/liter) in water stored in them over a 6-month period. Concentrations measured in plastic bottles were generally much lower, and ranged from <1 to 761 ng/liter with a median of 8.5 ng/liter. The artesian sources exhibited a median lead concentration of 5.1 ng/liter in a much narrower range. — JSY

Environ. Sci. Technol. 41, 10.1021/es062964h (2007).

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