NITRO, W.VA.—Jack Woodall worked at the plant for 30 years. In his first year and part of the second, he made weedkiller. That's the way it worked. The new guys at the plant had to make the weedkiller. It was a rite of passage.

First they mixed the chemicals, then dried them to form a powder or cake. Then the powder was bagged and sent away.

At the end of each day, they had to clean. They swept the extra powder into bins so it could be taken to landfills and burned, Woodall says. They hosed the equipment from top to bottom, washing the extra chemicals into the sewer. [See photos of Nitro, W. Va.]

The fumes from the chemicals were noxious. They caused workers' skin to blister. To protect their faces, Woodall and his coworkers were given jars of cream. That didn't help very much.

This was in 1961 and part of 1962. Today, Woodall still smells the chemicals. He smells them coming from his skin when he sweats, and in the summer his pillowcases turn yellow where the fabric touches his cheek. "I know the smell anywhere," he says. "I know the old dioxin smell."

The plant was owned by Monsanto and was in a sprawling compound along the edge of the Kanawha River about 15 miles northwest of Charleston, the state capital. Monsanto made all sorts of chemicals there, including the weedkiller with the chemical name 2,4,5-T. With so many different materials being combined, there were always byproducts, and dioxin was one of them.

Dioxin is best known for being a contaminant in Agent Orange, a herbicide used in Vietnam. The military sprayed it widely to clear the jungles. The Vietnamese refer to it as "the last ghost" of the war. More than half a million Vietnamese children have been born with birth defects. Agent Orange has been linked to leukemia in American Vietnam veterans.

The United States has its ghosts, too. For the better part of 30 years, Nitro has been grappling with the legacy of dioxin. The plant is long gone, leaving a vacant lot, part gravel and part pavement, with weeds—weeds, of all things—growing here and there in the cracks. In one direction, an old water tower, once white but now covered with rust, watches over the town; in the other direction, the long smokestacks of the John E. Amos Coal Plant in the neighboring town of Poca rise in the distance.

Cleanup. The only things that hint of what was here are signs that say "No Trespassing. Solutia, Inc." Monsanto spun off Solutia as a separate company in 1997. It inherited many of the problems Monsanto left behind. Solutia is about to start work on a four-to-five-year project to keep any of the chemicals that are still in the soil at the Nitro plant site from getting into the water.

The Environmental Protection Agency has been in and out of Nitro for nearly half a century. In the mid-1980s, under EPA orders, Monsanto investigated part of the site and, after finding soil contaminated with dioxin, removed about 500 gallons of soil, the EPA says. More than a decade later, investigators turned to the water. The state and the EPA found that two rivers and one creek were contaminated. They homed in on a 14-mile stretch of the Kanawha near the old site. Starting in 2004, Monsanto began testing fish, such as bass and catfish and other bottom feeders, in the river and sampling the water and the sediment of the riverbed. Monsanto sent the results to the EPA last year. Now the agency has to decide what to do.

It is not just that site. There's an old landfill of the type Woodall described, where Monsanto and other local businesses dumped waste, on Heizer Creek about a mile northeast of Poca, where he lives. The company stopped using that particular site in 1960, a year before Woodall started working. The EPA investigated in the 1980s and found contamination. Monsanto tried to clean it up. In 1998, the EPA came back, sampled again, and found more dioxin. According to the EPA, the cleanup is ongoing. Altogether, this town and the surrounding area have four active cleanup sites—three from Monsanto, the other from a company called Fike Chemical.

As hard as it is to clean up soil, at least there's a chance. With people, there's no such possibility. In 1991, Woodall retired after 30 years of service, and Monsanto gave him a plaque with a photo of the site in a wooden frame. After the herbicide job, he had worked at the site as an insulator and machinist. The workers were a family.

About a year after he retired, Woodall developed colon cancer. Maybe dioxin had something to do with it; maybe it didn't. But thousands of Nitro residents or former residents are part of a class action lawsuit that alleges the company polluted the town with dioxin. Woodall, having worked at the plant and lived in Nitro, is a class member of the suit. Another 161 lawsuits from residents claim dioxin has caused their cancers. Monsanto says the cases lack merit. "We will defend ourselves vigorously," says spokesman Bob Pierce.

Elevated risk. When Woodall started at the plant, it's fair to say not much was known about dioxin's long-term effects. Yes, it burned the skin and smelled foul. But the United States didn't formally start studying it until 1962, and it wasn't really until after the 1970s, after Vietnam and a major chemical accident near the town of Seveso, Italy, that data started to come out.

In the 1976 accident in Seveso, a plant released dioxin. Since then, researchers have studied residents of the area and found elevated risks of certain cancers and spikes in infertility accompanying increased exposure to dioxin. But there and elsewhere, controversy has dogged the science. The EPA has worked for the better part of two decades to issue a comprehensive report on the health hazards posed by the chemical. It has been delayed by squabbles between agencies and by concerns among some scientists that the risks were overstated.

Lisa Jackson, the EPA administrator, could kick the can down the road, but she said in an interview last year that tackling dioxin is one of her priorities. Since then, the EPA has completed a draft of that long-delayed report; it's currently being peer-reviewed, and the agency hopes to release a final draft this year. By itself, it won't prompt any new rules. But it will give the clearest look yet at what dioxin does to the body. "The real evolution in the science is that we have a deeper under­stand­ing not only that it is toxic but of how it gets into the body and how it accumulates in the body," says Paul Anastas, head of the EPA's Office of Research and Development. Meanwhile, in January, the EPA proposed a rule that would greatly reduce the level of dioxin allowed in soil near homes.

As the EPA's experience shows, it's not easy to deal with chemicals after they're released. In Nitro, it's even more complicated. The fact that Nitro exists at all is because of chemicals. The town was essentially built from scratch in 1918 to make ammunition for World War I. The name Nitro comes from nitro­cellulose, a chemical. The ­military designed the town to accommodate 18,000 workers. After the war, some of the factories switched to producing rubber, and in the 1940s Monsanto bought a site to make agricultural chemicals. For decades, the plant gave people jobs and salaries. For workers like Woodall, it's hard to hate something like that.

But the former workers aren't the only ones affected. In Nitro, townspeople know not to eat fish from the local waters. They've received letters from health authorities warning them of the risks. That's something scientists have tracked for a while. "For most people, more than 90 percent of the daily intake of dioxin and dioxinlike compounds comes from food, primarily meat, dairy products, and fish," says Tom Sinks, deputy director of the federal Agency for Toxic Substances and Disease Registry.

Several years ago, a local law firm, the Calwell Practice, started conducting dioxin tests inside people's homes. Samples also were taken from public schools and a community center. The firm says elevated levels of dioxin were found. Several government agencies reviewed the results and concluded that the dioxin levels "do not pose a health problem."

"What in the world could you do to clean up Nitro?" asks Woodall, who let the lawyers test inside his home. "You just have to let the judge and the lawyers and the company fight it out. I have no idea what they're trying to do."

Dioxin is one of only a handful of chemicals the EPA has banned from industrial manufacturing, yet it is still produced as a byproduct in many plants. And maybe its longevity is a warning. An effort is underway in Congress to update the Toxic Substances Control Act, which governs human-created chemicals. When it was passed in 1976, it grandfathered in tens of thousands of chemicals, meaning none of them had to be approved for safety. Now there's a push to shift the burden to industry, to make manufacturers prove that chemicals are safe before they're created on a big scale.