PERHAM, MINN. -- When Tom Hammers accidentally cuts his finger, he can't feel the pain.

His nerves were damaged at age 16 by drinking water from a tainted well. It happened in 1972, the summer that changed his life.

That year, Hammers and 12 other employees of his father's construction business drank water from a new well at the company's office. The water tasted good. Nobody knew the well had penetrated an old arsenic dump.

Even now, 35 years after the poisonings, it is the only documented case in Minnesota of chronic illness traced to chemical dumping and polluted groundwater. Its lesson is still relevant today because the arsenic contamination that caused it -- like the tainted groundwater around many old dump sites -- still isn't fully cleaned up.

The case has been written up in two medical journals.

For Tom Hammers, now 51, arsenic is part of the story of his life. And the story begins before he was born.

In 1931, farmers across the Midwest faced a scourge of grasshoppers and crickets that devoured entire fields of crops.

Perham, located in lake country about 180 miles northwest of the Twin Cities, didn't escape the hordes. Otter Tail County's farmers were desperate for help.

Modern insecticides hadn't arrived in the 1930s. Instead, the U.S. Department of Agriculture supplied Minnesota farmers with poison bait -- a mix of bran, sawdust, molasses, water and an arsenic compound -- to spread on the fields. In Perham, workers mixed the local allotment at a shack on the edge of the Otter Tail County fairgrounds.

When the eradication program ended in the 1940s, many 100-pound bags of bait containing perhaps 50 pounds of arsenic compound were left over in Perham. Workers dug a shallow trench at the fairgrounds and buried the surplus in the sandy soil.

The arsenic was still there, long forgotten, oozing into the groundwater, nearly 25 years later. That's when Hammers' father, Bob, purchased adjacent property. He erected an office and warehouse for his construction company and installed a well just 31 feet deep.

Tom Hammers, just out of his freshman year in high school, joined the summer construction crew that also included his 34-year-old uncle, John Altstadt. Each day, before heading to a job site, the two filled jugs with water from the new well.

"It was hot, and we're drinking lots of water after lunch, and you'd start to getting flu-type symptoms, nausea," Tom Hammers said.

The sickness continued for 10 weeks, affecting others on the crew as well as Bob Hammers, who worked in the office and drank coffee brewed with the well water.

Tom Hammers and Altstadt suffered the worst. Slowly, they got weaker. Then their hands and feet became numb.

"They couldn't figure out what was the matter with them and why they kept having flu symptoms," recalled Florence Hammers, who watched in alarm the decline of her husband, her son and her brother.

Soon Altstadt could barely walk, so his doctor arranged for him to see a brain specialist in Fargo, N.D. "That was where he was at when they diagnosed arsenic poisoning," recalled his widow, Rosie Altstadt.

He was admitted to a Fargo hospital with his doctor fearing for his life, she said.