By Janet Raloff
Water contaminated with manganese not only tastes vile but also can limit the intellectual development of children drinking it, a new study finds.
While studying the arsenic-tainted wells of Bangladesh several years ago, scientists turned up another natural pollutant there: manganese. The World Health Organization’s pollutant standard for the metal is 500 micrograms per liter (µg/l) of drinking water, and contamination in some Bangladesh wells far exceeded that amount.
To assess manganese’s independent threat, researchers identified low-arsenic wells contaminated with various amounts of manganese. They grouped the wells into four categories. The least-tainted wells had less than 200 µg/l of manganese, and the most-contaminated wells all carried more than 1,000 µg/l of the metal.