Silent Killer Taking Toll

Villagers emerge from the shade of their homes and gingerly roll up their sleeves, turning their palms upwards to reveal skin braided with dark lesions, ulcers and decaying tissue. They point to houses up and down the street where people have died of symptoms like theirs.

Arsenic, an invisible, odourless poison, has haunted this village in Kandal’s Koh Thom district. Most have been diagnosed with arsenic poisoning, and many have lost children or parents to it.

“The children are scared of my disease,” says Chhang Vern, 40. He unbuttons his shirt to show hyper-pigmentation covering his chest, stomach and back, and extending down his arms and legs. His children turn away as he lifts his feet and points to blackened, oozing sores.

Hundreds of thousands of Cambodians are at risk of inadvertent, mass poisoning in the same manner, experts say.

Over the past 15 years, extremely high levels of arsenic have been detected in food and well water in 10 provinces, with the highest concentrations found in Kandal, Kampong Cham and Prey Veng. Once ingested, the cancer-causing toxin can take years to do its lethal work, and experts predict Cambodia has yet to experience the full extent of the poison’s dire health consequences.

The arsenic, a naturally occurring toxin, comes from polluted groundwater dredged up by hand-operated pumps called tube wells, according to Stanford University soil biochemist Scott Fender.

Starting in the 1980s, a UNICEF-led safe-water program pioneered Cambodia’s vast network of community tube wells, installing pumps as an easy and inexpensive alternative to bacteria-infested surface water. An independent report commissioned by UNICEF in 2006, however, found that such tube wells installed in arsenic-affected areas were contaminated.

“Arsenic is a silent killer; it has no taste and no smell. You can only know if it’s there by testing for it,” Sophary Phan, a technical officer at the World Health Organization Cambodia, said.

Arsenic contamination was discovered in Cambodia during a 1999 national water-quality survey. By 2006, the first cases of arsenicosis - arsenic poisoning - were diagnosed.

“Arsenic is one of the most toxic, carcinogenic molecules we know of,” said Dr Craig Steinmaus, an epidemiologist at the University of California at Berkeley. “But you don’t get exposed one day and get cancer the next. Most of the health effects happen down the line.”

But efforts to calculate how many people are or may become sick have revealed a trail of unknown variables: how many wells are...