May 30, 2005
Volume 83, Number 22
pp. 68-69


VENOMOUS EARTH: How arsenic caused the world's worst mass poisoning, by Andrew A. Meharg, Macmillan, 2005, 192 pages, $29.95 (ISBN 1-4039-4499-7)



"Venomous Earth" by Andrew A. Meharg delivers far more than the subtitle suggests: "How arsenic caused the world's worst mass poisoning." This is not a bargain, however.

Meharg, a professor of biogeochemistry at the University of Aberdeen, in Scotland, would have served his readers better by skipping several chapters of historical review and focusing only on the title's subject: the suffering of tens of millions of people in the Ganges Delta of Bangladesh and India from drinking water contaminated with naturally occurring arsenic. It's a compelling concern.

The water in question comes from millions of tube wells, which are shallow wells sunk into soft sediments laid down by flooding over millennia. These wells have been installed mainly through international development projects during the past three decades and were intended to provide safe drinking water for people who depended on river water.

The well water has spared the population, especially the very young, from the often-fatal ravages of waterborne diseases. But as Meharg points out, arsenic is slowly sickening millions of people in Bangladesh and the Indian state of West Bengal who drink the well water and use it to irrigate fields.

Studies documenting arsenic-related health problems as far back as 1984 were ignored while installation of tube wells carried on apace, Meharg notes. "Unlike a famine or civil war, where the scale of human suffering is immediately obvious, arsenic is an insidious killer. Its victims die slowly in remote villages, hidden away from the media's glare."

Meharg's explanations of the biogeochemical processes by which arsenic ends up concentrating in water-bearing strata are fascinating. Those strata, which occur between 10 and 150 meters below the surface, were laid down in the past 7,000 years in a delta rich with mangrove trees. Meharg developed a theory about how arsenic ends up in these sediments through observations he made in a mangrove forest bordering the Bay of Bengal.

"The sediments are packed so tightly that oxygen cannot get in," Meharg writes. "In response, the trees pump oxygen down and out of their roots to oxygenate their microenvironment. In this microenvironment, orange-brown bands of iron oxyhydroxides form readily, and oxidized arsenic binds easily to these minerals."

TAKE HEED A Bangladeshi village survey member paints an unsafe well red.
Meanwhile, mangroves shed roots, leaves, and bark that add carbon to the sediment, Meharg adds. Over time, the breakdown of carbon compounds creates reducing conditions in the sediment, which releases the bound arsenic into groundwater. As the sediments mature, their buried organic matter gets used up, and the liberation of arsenic abates.

After these absorbing explanations, however, too much of the book is devoted to information that, while instructive, is not germane to Meharg's concerns about the arsenic-tainted well water in the Ganges Delta region. He spends one long chapter discussing the intentional use of arsenic throughout history, especially in alchemy.

The book then wends through an exhaustively researched section on the use of copper arsenite, which provided a popular green coloring used in wallpaper, upholstery, and clothing during the 1800s. Meharg traces widespread arsenic poisoning in Britain during this time, within homes as well as at work sites where arsenic ore was mined and processed or goods were manufactured with the substance. He paints an excruciatingly documented--and ultimately villainous--portrait of Victorian designer William Morris, who profited from arsenic mining as well as the sales of wallpaper printed with arsenic pigments. Interspersed in the detailed history of Morris are poorly placed chapters on the use of arsenic in medicine and homicide.

Meharg concludes by returning to his title topic, describing the complexities of the well water problem in Bangladesh and exploring a host of possible solutions to the arsenic-polluted tube wells. He's a thorough examiner of these options and concludes that none is cheap or easy to implement, either financially or culturally.

The issue has the attention of the National Academy of Engineering. It announced in February the establishment of the Grainger Challenge Prize for Sustainable Development. The first contest for this $1 million award is for the design of an inexpensive system to reduce arsenic levels in drinking water in developing countries (C&EN, Feb. 7, page 10). Researchers in England have found a possible answer already: Dried roots of the water hyacinth can rapidly remove arsenic from water (C&EN, April 4, page 12).

Meharg also argues for preventive action so arsenic poisoning doesn't become more widespread. He urges aid agencies to shun "the indiscriminate sinking of tube wells into alluvial sediments in Southeast Asia," not just in Bangladesh and India. Such tube wells, he warns, will have a high probability of drawing groundwater tainted with arsenic. Aquifers need to be tested carefully before tube wells are installed.

Though buried at the end of the book, bogged down in a historical review of arsenic, Meharg's warning is of great importance. It needs to be heeded.

Cheryl Hogue is a senior editor with C&EN's government and policy staff. She covers environmental issues, including regulation of arsenic in U.S. drinking water.

  Chemical & Engineering News
ISSN 0009-2347
Copyright © 2005