The town of Butte sits on a hill just west of the Continental Divide in southwestern Montana. A few blocks from the sleepy town’s center lies Berkeley Pit, an abandoned open-pit mine stretching a mile-and-a-half across and almost 2,000 feet deep. Once called the “Richest Hill on Earth” for its massive copper deposits, today Butte and the Berkeley Pit are part of an expanse of waste that makes up the nation’s largest EPA Superfund site.

Incredibly, a stray dog lived for 17 years in the midst of this polluted landscape. For years he was known only to a few workers at an active mine nearby, who named him “Auditor” because he always showed up unexpectedly. They never imagined that Auditor’s tale would prompt a local scientist to begin a research project that would shed light on the extent of environmental degradation in Butte — and that could be used to track pollution the world over.

In the early 1900s, Butte boasted a population of 100,000. Mining companies were pulling copper from the Butte hill at the same time the U.S. was wiring the country. But the mines shut down by 1982, leaving behind just 30,000 people, a crippled economy and a toxic mess. Piles of mine waste and years of smoke from smelters contaminated the land and water around Butte with arsenic, mercury and lead, among other metals. These heavy metals wreak havoc on the environment and have been linked to mental deficiencies, heart disease and cancer.

Butte’s public health problems are insidious and complex, but the Berkeley Pit is undeniably hostile to life. Its walls of barren soil surround an acidic lake chock-full of heavy metals. In 1995, a migrating flock of snow geese mistakenly spent a night on the Pit lake; 342 birds were found dead in the water the next morning, their internal organs burned and covered in sores. 


But Auditor (show right) — his face and legs hidden behind a thick, yellow mop of dreadlocks that dragged on the ground — somehow managed to make the Pit his home. The miners tried to look after him and occasionally left him food (he apparently had a taste for Twinkies). But Auditor avoided people and would disappear for months into the Pit.

Holly Peterson, an environmental engineer at Montana Tech in Butte, first heard about Auditor when his story appeared in the local paper in 2003.

“I couldn’t get his unkempt image out of my mind,” Peterson says. That summer, she tracked Auditor down and took a sample of his hair. When analyzed, “his hair revealed elevated levels of almost every element imaginable,” Peterson says, including 128 times the amount of arsenic in a typical dog’s hair.

Auditor died later that year, some 120 dog-years old. But inspired by Auditor, Peterson began an innovative research program. For the past several years, she and her students have analyzed the hair of hundreds of pets to screen for metals in people’s homes and yards.

Peterson’s work, published in the Intermountain Journal of Sciences last October, marks the first time pet hair has been used to monitor toxins in a residential Superfund site. Her team found higher levels of heavy metals in Butte pets compared to surrounding communities. And they found differences within Butte, showing where the EPA cleanup has worked and where it hasn’t.

Hair analysis can be tricky and controversial. Because toxin levels in hair may not accurately predict health effects, the American Medical Association disapproves of using hair analysis to make decisions about medical treatment. But most scientists think it has value in screening for heavy metal exposure, especially when comparing populations.

According to Safdar Khan, director of toxicology at the Animal Poison Control Center of the American Society for the Prevention of Cruelty to Animals, it can be hard to interpret hair analysis results because of the lack of data about what is “normal.” But, he says, as a screening tool it “can be a very useful indicator of what’s in the environment.” And pets are good “sentinel” species because they share their owners’ environment, and the analysis isn't complicated by changing diets or hair products.

Peterson hopes her approach can be used in other polluted areas, too. One graduate student, Melody Madden, has used the method in Broken Hill, Australia, a mining town similar to Butte. Another student is using hair analysis to study pollution in Nairobi, Kenya. Through their work, these animals all become auditors of our environment, our homes, and our health.

Story by Soren Wheeler. This article originally appeared in "Plenty" in August 2007.

Copyright Environ Press 2007