Just months before Rob Bilott made partner at Taft Stettinius & Hollister,  he received a call on his direct line from a cattle farmer. The farmer, Wilbur  Tennant of Parkersburg, W.Va., said that his cows were dying left and right. He  believed that the DuPont chemical company, which until recently operated a site  in Parkersburg that is more than 35 times the size of the Pentagon, was  responsible. Tennant had tried to seek help locally, he said, but DuPont just  about owned the entire town. He had been spurned not only by Parkersburg's  lawyers but also by its politicians, journalists, doctors and veterinarians.  The farmer was angry and spoke in a heavy Appalachian accent. Bilott struggled  to make sense of everything he was saying. He might have hung up had Tennant  not blurted out the name of Bilott's grandmother, Alma Holland White.
         
        White had lived in Vienna, a northern suburb of Parkersburg,  and as a child, Bilott often visited her in the summers. In 1973 she brought  him to the cattle farm belonging to the Tennants' neighbors, the Grahams, with  whom White was friendly. Bilott spent the weekend riding horses, milking cows  and watching Secretariat win the Triple Crown on TV. He was 7 years old. The  visit to the Grahams' farm was one of his happiest childhood memories.
         
        When the Grahams heard in 1998 that Wilbur Tennant was  looking for legal help, they remembered Bilott, White's grandson, who had grown  up to become an environmental lawyer. They did not understand, however, that  Bilott was not the right kind of environmental lawyer. He did not represent  plaintiffs or private citizens. Like the other 200 lawyers at Taft, a firm  founded in 1885 and tied historically to the family of President William Howard  Taft, Bilott worked almost exclusively for large corporate clients. His  specialty was defending chemical companies. Several times, Bilott had even  worked on cases with DuPont lawyers. Nevertheless, as a favor to his grandmother,  he agreed to meet the farmer. ''It just felt like the right thing to do,'' he  says today. ''I felt a connection to those folks.''
         
        The connection was not obvious at their first meeting. About  a week after his phone call, Tennant drove from Parkersburg with his wife to  Taft's headquarters in downtown Cincinnati. They hauled cardboard boxes  containing videotapes, photographs and documents into the firm's glassed-in  reception area on the 18th floor, where they sat in gray midcentury-modern  couches beneath an oil portrait of one of Taft's founders. Tennant — burly and  nearly six feet tall, wearing jeans, a plaid flannel shirt and a baseball cap —  did not resemble a typical Taft client. ''He didn't show up at our offices  looking like a bank vice president,'' says Thomas Terp, a partner who was  Bilott's supervisor. ''Let's put it that way.''
        
    Terp joined Bilott for the meeting. Wilbur Tennant explained that he and his  four siblings had run the cattle farm since their father abandoned them as children.  They had seven cows then. Over the decades they steadily acquired land and  cattle, until 200 cows roamed more than 600 hilly acres. The property would  have been even larger had his brother Jim and Jim's wife, Della, not sold 66  acres in the early '80s to DuPont. The company wanted to use the plot for a  landfill for waste from its factory near Parkersburg, called Washington Works,  where Jim was employed as a laborer. Jim and Della did not want to sell, but  Jim had been in poor health for years, mysterious ailments that doctors  couldn't diagnose, and they needed the money.
         
        DuPont rechristened the plot Dry Run Landfill, named after  the creek that ran through it. The same creek flowed down to a pasture where  the Tennants grazed their cows. Not long after the sale, Wilbur told Bilott,  the cattle began to act deranged. They had always been like pets to the  Tennants. At the sight of a Tennant they would amble over, nuzzle and let  themselves be milked. No longer. Now when they saw the farmers, they charged.
        
    Wilbur fed a videotape into the VCR. The footage, shot on a camcorder, was  grainy and intercut with static. Images jumped and repeated. The sound  accelerated and slowed down. It had the quality of a horror movie. In the  opening shot the camera pans across the creek. It takes in the surrounding  forest, the white ash trees shedding their leaves and the rippling, shallow  water, before pausing on what appears to be a snowbank at an elbow in the creek.  The camera zooms in, revealing a mound of soapy froth.
         
        ''I've taken two dead deer and two dead cattle off this  ripple,'' Tennant says in voice-over. ''The blood run out of their noses and  out their mouths. ... They're trying to cover this stuff up. But it's not going  to be covered up, because I'm going to bring it out in the open for people to  see.''
         
        The video shows a large pipe running into the creek,  discharging green water with bubbles on the surface. ''This is what they expect  a man's cows to drink on his own property,'' Wilbur says. ''It's about high  time that someone in the state department of something-or-another got off their  cans.''
         
        At one point, the video cuts to a skinny red cow standing in  hay. Patches of its hair are missing, and its back is humped — a result, Wilbur  speculates, of a kidney malfunction. Another blast of static is followed by a  close-up of a dead black calf lying in the snow, its eye a brilliant, chemical  blue. ''One hundred fifty-three of these animals I've lost on this farm,''  Wilbur says later in the video. ''Every veterinarian that I've called in  Parkersburg, they will not return my phone calls or they don't want to get  involved. Since they don't want to get involved, I'll have to dissect this  thing myself. ... I'm going to start at this head.''
         
        The video cuts to a calf's bisected head. Close-ups follow  of the calf's blackened teeth (''They say that's due to high concentrations of  fluoride in the water that they drink''), its liver, heart, stomachs, kidneys  and gall bladder. Each organ is sliced open, and Wilbur points out unusual  discolorations — some dark, some green — and textures. ''I don't even like the  looks of them,'' he says. ''It don't look like anything I've been into  before.''
         
        Bilott watched the video and looked at photographs for  several hours. He saw cows with stringy tails, malformed hooves, giant lesions  protruding from their hides and red, receded eyes; cows suffering constant  diarrhea, slobbering white slime the consistency of toothpaste, staggering  bowlegged like drunks. Tennant always zoomed in on his cows' eyes. ''This cow's  done a lot of suffering,'' he would say, as a blinking eye filled the screen.
         
        ''This is bad,'' Bilott said to himself. ''There's something  really bad going on here.''
         
        Bilott decided right away to take the Tennant case. It was,  he says again, ''the right thing to do.'' Bilott might have had the practiced  look of a corporate lawyer — soft-spoken, milk-complected, conservatively  attired — but the job had not come naturally to him. He did not have a typical  Taft résumé. He had not attended college or law school in the Ivy League. His  father was a lieutenant colonel in the Air Force, and Bilott spent most of his  childhood moving among air bases near Albany; Flint, Mich.; Newport Beach,  Calif.; and Wiesbaden, West Germany. Bilott attended eight schools before  graduating from Fairborn High, near Ohio's Wright-Patterson Air Force Base. As  a junior, he received a recruitment letter from a tiny liberal-arts school in  Sarasota called the New College of Florida, which graded pass/fail and allowed  students to design their own curriculums. Many of his friends there were  idealistic, progressive — ideological misfits in Reagan's America. He met with  professors individually and came to value critical thinking. ''I learned to  question everything you read,'' he said. ''Don't take anything at face value.  Don't care what other people say. I liked that philosophy.'' Bilott studied  political science and wrote his thesis about the rise and fall of Dayton. He  hoped to become a city manager.
         
        But his father, who late in life enrolled in law school,  encouraged Bilott to do the same. Surprising his professors, he chose to attend  law school at Ohio State, where his favorite course was environmental law. ''It  seemed like it would have real-world impact,'' he said. ''It was something you  could do to make a difference.'' When, after graduation, Taft made him an  offer, his mentors and friends from New College were aghast. They didn't  understand how he could join a corporate firm. Bilott didn't see it that way.  He hadn't really thought about the ethics of it, to be honest. ''My family said  that a big firm was where you'd get the most opportunities,'' he said. ''I knew  nobody who had ever worked at a firm, nobody who knew anything about it. I just  tried to get the best job I could. I don't think I had any clue of what that involved.''
         
        At Taft, he asked to join Thomas Terp's environmental team.  Ten years earlier, Congress passed the legislation known as Superfund, which  financed the emergency cleanup of hazardous-waste dumps. Superfund was a  lucrative development for firms like Taft, creating an entire subfield within  environmental law, one that required a deep understanding of the new  regulations in order to guide negotiations among municipal agencies and  numerous private parties. Terp's team at Taft was a leader in the field.
         
        As an associate, Bilott was asked to determine which  companies contributed which toxins and hazardous wastes in what quantities to  which sites. He took depositions from plant employees, perused public records  and organized huge amounts of historical data. He became an expert on the  Environmental Protection Agency's regulatory framework, the Safe Drinking Water  Act, the Clean Air Act, the Toxic Substances Control Act. He mastered the  chemistry of the pollutants, despite the fact that chemistry had been his worst  subject in high school. ''I learned how these companies work, how the laws  work, how you defend these claims,'' he said. He became the consummate insider.
         
        Bilott was proud of the work he did. The main part of his  job, as he understood it, was to help clients comply with the new regulations.  Many of his clients, including Thiokol and Bee Chemical, disposed of hazardous  waste long before the practice became so tightly regulated. He worked long  hours and knew few people in Cincinnati. A colleague on Taft's environmental  team, observing that he had little time for a social life, introduced him to a  childhood friend named Sarah Barlage. She was a lawyer, too, at another  downtown Cincinnati firm, where she defended corporations against  worker's-compensation claims. Bilott joined the two friends for lunch. Sarah  doesn't remember him speaking. ''My first impression was that he was not like  other guys,'' she says. ''I'm pretty chatty. He's much quieter. We complemented  each other.''
        
    They married in 1996. The first of their three sons was born two years later.  He felt secure enough at Taft for Barlage to quit her job and raise their  children full-time. Terp, his supervisor, recalls him as ''a real standout  lawyer: incredibly bright, energetic, tenacious and very, very thorough.'' He  was a model Taft lawyer. Then Wilbur Tennant came along.
         
        The Tennant case put Taft in a highly unusual position. The  law firm was in the business of representing chemical corporations, not suing  them. The prospect of taking on DuPont ''did cause us pause,'' Terp concedes.  ''But it was not a terribly difficult decision for us. I'm a firm believer that  our work on the plaintiff's side makes us better defense lawyers.''
         
        Bilott sought help with the Tennant case from a West  Virginia lawyer named Larry Winter. For many years, Winter was a partner at  Spilman, Thomas & Battle — one of the firms that represented DuPont in West  Virginia — though he had left Spilman to start a practice specializing in personal-injury  cases. He was amazed that Bilott would sue DuPont while remaining at Taft.
         
        ''His taking on the Tennant case,'' Winter says, ''given the  type of practice Taft had, I found to be inconceivable.''
         
        Bilott, for his part, is reluctant to discuss his motivations  for taking the case. The closest he came to elaborating was after being asked  whether, having set out ''to make a difference'' in the world, he had any  misgivings about the path his career had taken.
         
        ''There was a reason why I was interested in helping out the  Tennants,'' he said after a pause. ''It was a great opportunity to use my  background for people who really needed it.''
         
        Bilott filed a federal suit against DuPont in the summer of  1999 in the Southern District of West Virginia. In response, DuPont's in-house  lawyer, Bernard Reilly, informed him that DuPont and the E.P.A. would  commission a study of the property, conducted by three veterinarians chosen by  DuPont and three chosen by the E.P.A. Their report did not find DuPont responsible  for the cattle's health problems. The culprit, instead, was poor husbandry:  ''poor nutrition, inadequate veterinary care and lack of fly control.'' In  other words, the Tennants didn't know how to raise cattle; if the cows were  dying, it was their own fault.
         
        This did not sit well with the Tennants, who began to suffer  the consequences of antagonizing Parkersburg's main employer. Lifelong friends  ignored the Tennants on the streets of Parkersburg and walked out of  restaurants when they entered. ''I'm not allowed to talk to you,'' they said,  when confronted. Four different times, the Tennants changed churches.
         
        Wilbur called the office nearly every day, but Bilott had  little to tell him. He was doing for the Tennants what he would have done for  any of his corporate clients — pulling permits, studying land deeds and  requesting from DuPont all documentation related to Dry Run Landfill  -  but he  could find no evidence that explained what was happening to the cattle. ''We  were getting frustrated,'' Bilott said. ''I couldn't blame the Tennants for  getting angry.''
         
         
        With the trial looming, Bilott stumbled upon a letter DuPont  had sent to the E.P.A. that mentioned a substance at the landfill with a  cryptic name: ''PFOA.'' In all his years working with chemical companies, Bilott  had never heard of PFOA. It did not appear on any list of regulated materials,  nor could he find it in Taft's in-house library. The chemistry expert that he  had retained for the case did, however, vaguely recall an article in a trade  journal about a similar-sounding compound: PFOS, a soaplike agent used by the  technology conglomerate 3M in the fabrication of Scotchgard.
         
        Bilott hunted through his files for other references to  PFOA, which he learned was short for perfluorooctanoic acid. But there was nothing.  He asked DuPont to share all documentation related to the substance; DuPont  refused. In the fall of 2000, Bilott requested a court order to force them.  Against DuPont's protests, the order was granted. Dozens of boxes containing  thousands of unorganized documents began to arrive at Taft's headquarters:  private internal correspondence, medical and health reports and confidential  studies conducted by DuPont scientists. There were more than 110,000 pages in  all, some half a century old. Bilott spent the next few months on the floor of  his office, poring over the documents and arranging them in chronological  order. He stopped answering his office phone. When people called his secretary,  she explained that he was in the office but had not been able to reach the  phone in time, because he was trapped on all sides by boxes.
         
        ''I started seeing a story,'' Bilott said. ''I may have been  the first one to actually go through them all. It became apparent what was  going on: They had known for a long time that this stuff was bad.''
         
        Bilott is given to understatement. (''To say that Rob Bilott  is understated,'' his colleague Edison Hill says, ''is an understatement.'')  The story that Bilott began to see, cross-legged on his office floor, was  astounding in its breadth, specificity and sheer brazenness. ''I was shocked,''  he said. That was another understatement. Bilott could not believe the scale of  incriminating material that DuPont had sent him. The company appeared not to  realize what it had handed over. ''It was one of those things where you can't  believe you're reading what you're reading,'' he said. ''That it's actually  been put in writing. It was the kind of stuff you always heard about happening  but you never thought you'd see written down.''
         
        The story began in 1951, when DuPont started purchasing PFOA  (which the company refers to as C8) from 3M for use in the manufacturing of  Teflon. 3M invented PFOA just four years earlier; it was used to keep coatings  like Teflon from clumping during production. Though PFOA was not classified by  the government as a hazardous substance, 3M sent DuPont recommendations on how  to dispose of it. It was to be incinerated or sent to chemical-waste  facilities. DuPont's own instructions specified that it was not to be flushed  into surface water or sewers. But over the decades that followed, DuPont pumped  hundreds of thousands of pounds of PFOA powder through the outfall pipes of the  Parkersburg facility into the Ohio River. The company dumped 7,100 tons of  PFOA-laced sludge into ''digestion ponds'': open, unlined pits on the  Washington Works property, from which the chemical could seep straight into the  ground. PFOA entered the local water table, which supplied drinking water to  the communities of Parkersburg, Vienna, Little Hocking and Lubeck  -  more than  100,000 people in all.
         
        Bilott learned from the documents that 3M and DuPont had  been conducting secret medical studies on PFOA for more than four decades. In  1961, DuPont researchers found that the chemical could increase the size of the  liver in rats and rabbits. A year later, they replicated these results in  studies with dogs. PFOA's peculiar chemical structure made it uncannily  resistant to degradation. It also bound to plasma proteins in the blood,  circulating through each organ in the body. In the 1970s, DuPont discovered  that there were high concentrations of PFOA in the blood of factory workers at  Washington Works. They did not tell the E.P.A. at the time. In 1981, 3M  -  which  continued to serve as the supplier of PFOA to DuPont and other corporations  -  found that ingestion of the substance caused birth defects in rats. After 3M  shared this information, DuPont tested the children of pregnant employees in  their Teflon division. Of seven births, two had eye defects. DuPont did not  make this information public.
         
        In 1984, DuPont became aware that dust vented from factory  chimneys settled well beyond the property line and, more disturbing, that PFOA  was present in the local water supply. DuPont declined to disclose this finding.  In 1991, DuPont scientists determined an internal safety limit for PFOA  concentration in drinking water: one part per billion. The same year, DuPont  found that water in one local district contained PFOA levels at three times  that figure. Despite internal debate, it declined to make the information  public.
         
        (In a statement, DuPont claimed that it did volunteer health  information about PFOA to the E.P.A. during those decades. When asked for  evidence, it forwarded two letters written to West Virginian government  agencies from 1982 and 1992, both of which cited internal studies that called  into question links between PFOA exposure and human health problems.)
         
        By the '90s, Bilott discovered, DuPont understood that PFOA  caused cancerous testicular, pancreatic and liver tumors in lab animals. One  laboratory study suggested possible DNA damage from PFOA exposure, and a study  of workers linked exposure with prostate cancer. DuPont at last hastened to  develop an alternative to PFOA. An interoffice memo sent in 1993 announced that  ''for the first time, we have a viable candidate'' that appeared to be less  toxic and stayed in the body for a much shorter duration of time. Discussions  were held at DuPont's corporate headquarters to discuss switching to the new  compound. DuPont decided against it. The risk was too great: Products  manufactured with PFOA were an important part of DuPont's business, worth $1  billion in annual profit.
         
        But the crucial discovery for the Tennant case was this: By  the late 1980s, as DuPont became increasingly concerned about the health  effects of PFOA waste, it decided it needed to find a landfill for the toxic  sludge dumped on company property. Fortunately they had recently bought 66  acres from a low-level employee at the Washington Works facility that would do  perfectly.
         
        By 1990, DuPont had dumped 7,100 tons of PFOA sludge into  Dry Run Landfill. DuPont's scientists understood that the landfill drained into  the Tennants' remaining property, and they tested the water in Dry Run Creek.  It contained an extraordinarily high concentration of PFOA. DuPont did not tell  this to the Tennants at the time, nor did it disclose the fact in the cattle  report that it commissioned for the Tennant case a decade later — the report  that blamed poor husbandry for the deaths of their cows. Bilott had what he  needed.
         
        In August 2000, Bilott called DuPont's lawyer, Bernard  Reilly, and explained that he knew what was going on. It was a brief  conversation.
         
        The Tennants settled. The firm would receive its contingency  fee. The whole business might have ended right there. But Bilott was not  satisfied.
         
        ''I was irritated,'' he says.
         
        DuPont was nothing like the corporations he had represented  at Taft in the Superfund cases. ''This was a completely different scenario.  DuPont had for decades been actively trying to conceal their actions. They knew  this stuff was harmful, and they put it in the water anyway. These were bad  facts.'' He had seen what the PFOA-tainted drinking water had done to cattle.  What was it doing to the tens of thousands of people in the areas around  Parkersburg who drank it daily from their taps? What did the insides of their  heads look like? Were their internal organs green?
         
        Bilott spent the following months drafting a public brief  against DuPont. It was 972 pages long, including 136 attached exhibits. His  colleagues call it ''Rob's Famous Letter.'' ''We have confirmed that the  chemicals and pollutants released into the environment by DuPont at its Dry Run  Landfill and other nearby DuPont-owned facilities may pose an imminent and  substantial threat to health or the environment,'' Bilott wrote. He demanded  immediate action to regulate PFOA and provide clean water to those living near  the factory. On March 6, 2001, he sent the letter to the director of every  relevant regulatory authority, including Christie Whitman, administrator of the  E.P.A., and the United States attorney general, John Ashcroft.
         
        DuPont reacted quickly, requesting a gag order to block  Bilott from providing the information he had discovered in the Tennant case to  the government. A federal court denied it. Bilott sent his entire case file to  the E.P.A.
         
        ''DuPont freaked out when they realized that this guy was  onto them,'' says Ned McWilliams, a young trial lawyer who later joined  Bilott's legal team. ''For a corporation to seek a gag order to prevent  somebody from speaking to the E.P.A. is an extraordinary remedy. You could  realize how bad that looks. They must have known that there was a small chance  of winning. But they were so afraid that they were willing to roll the dice.''
         
        With the Famous Letter, Bilott crossed a line. Though  nominally representing the Tennants  -  their settlement had yet to be concluded  -  Bilott spoke for the public, claiming extensive fraud and wrongdoing. He had  become a threat not merely to DuPont but also to, in the words of one internal  memo, ''the entire fluoropolymers industry''  -  an industry responsible for the  high-performance plastics used in many modern devices, including kitchen  products, computer cables, implantable medical devices and bearings and seals  used in cars and airplanes. PFOA was only one of more than 60,000 synthetic  chemicals that companies produced and released into the world without  regulatory oversight.
         
        Jim Tennant and his wife, Della, sold DuPont a 66-acre tract  of land that became part of the Dry Run Landfill.
    
    
        ''Rob's letter lifted the curtain on a whole new theater,''  says Harry Deitzler, a plaintiff's lawyer in West Virginia who works with Bilott.  ''Before that letter, corporations could rely upon the public misperception  that if a chemical was dangerous, it was regulated.'' Under the 1976 Toxic  Substances Control Act, the E.P.A. can test chemicals only when it has been  provided evidence of harm. This arrangement, which largely allows chemical  companies to regulate themselves, is the reason that the E.P.A. has restricted  only five chemicals, out of tens of thousands on the market, in the last 40  years.
         
        It was especially damning to see these allegations against  DuPont under the letterhead of one of the nation's most prestigious corporate  defense firms. ''You can imagine what some of the other companies that Taft was  representing  -  a Dow Chemical  -  might have thought of a Taft lawyer taking on DuPont,''  Larry Winter says. ''There was a threat that the firm would suffer  financially.'' When I asked Thomas Terp about Taft's reaction to the Famous  Letter, he replied, not quite convincingly, that he didn't recall one. ''Our  partners,'' he said, ''are proud of the work that he has done.''
         
        Bilott, however, worried that corporations doing business  with Taft might see things differently. ''I'm not stupid, and the people around  me aren't stupid,'' he said. ''You can't ignore the economic realities of the  ways that business is run and the way clients think. I perceived that there  were some 'What the hell are you doing?' responses.''
         
        The letter led, four years later, in 2005, to DuPont's  reaching a $16.5 million settlement with the E.P.A., which had accused the  company of concealing its knowledge of PFOA's toxicity and presence in the  environment in violation of the Toxic Substances Control Act. (DuPont was not  required to admit liability.) At the time, it was the largest civil  administrative penalty the E.P.A. had obtained in its history, a statement that  sounds more impressive than it is. The fine represented less than 2 percent of  the profits earned by DuPont on PFOA that year.
         
        Bilott never represented a corporate client again.
         
        The obvious next step was to file a class-action lawsuit  against DuPont on behalf of everyone whose water was tainted by PFOA. In all  ways but one, Bilott himself was in the ideal position to file such a suit. He  understood PFOA's history as well as anyone inside DuPont did. He had the  technical and regulatory expertise, as he had proved in the Tennant case. The  only part that didn't make sense was his firm: No Taft lawyer, to anyone's  recollection, had ever filed a class-action lawsuit.
         
        It was one thing to pursue a sentimental case on behalf of a  few West Virginia cattle farmers and even write a public letter to the E.P.A.  But an industry-threatening class-action suit against one of the world's  largest chemical corporations was different. It might establish a precedent for  suing corporations over unregulated substances and imperil Taft's bottom line.  This point was made to Terp by Bernard Reilly, DuPont's in-house lawyer,  according to accounts from Bilott's plaintiff's-lawyer colleagues; they say  Reilly called to demand that Bilott back off the case. (Terp confirms that Reilly  called him but will not disclose the content of the call; Bilott and Reilly  decline to speak about it, citing continuing litigation.) Given what Bilott had  documented in his Famous Letter, Taft stood by its partner.
         
        A lead plaintiff soon presented himself. Joseph Kiger, a  night-school teacher in Parkersburg, called Bilott to ask for help. About nine  months earlier, he received a peculiar note from the Lubeck water district. It  arrived on Halloween day, enclosed in the monthly water bill. The note explained  that an unregulated chemical named PFOA had been detected in the drinking water  in ''low concentrations,'' but that it was not a health risk. Kiger had  underlined statements that he found particularly baffling, like: ''DuPont  reports that it has toxicological and epidemiological data to support  confidence that exposure guidelines established by DuPont are protective of  human health.'' The term ''support confidence'' seemed bizarre, as did  ''protective of human health,'' not to mention the claim that DuPont's own data  supported its confidence in its own guidelines.
         
        Still, Kiger might have forgotten about it had his wife,  Darlene, not already spent much of her adulthood thinking about PFOA. Darlene's  first husband had been a chemist in DuPont's PFOA lab. (Darlene asked that he  not be named so that he wouldn't be involved in the local politics around the  case.) ''When you worked at DuPont in this town,'' Darlene says today, ''you  could have everything you wanted.'' DuPont paid for his education, it secured  him a mortgage and it paid him a generous salary. DuPont even gave him a free  supply of PFOA, which, Darlene says, she used as soap in the family's  dishwasher and to clean the car. Sometimes her husband came home from work sick  -  fever, nausea, diarrhea, vomiting  -  after working in one of the PFOA storage  tanks. It was a common occurrence at Washington Works. Darlene says the men at  the plant called it ''Teflon flu.''
         
        In 1976, after Darlene gave birth to their second child, her  husband told her that he was not allowed to bring his work clothes home  anymore. DuPont, he said, had found out that PFOA was causing health problems  for women and birth defects in children. Darlene would remember this six years  later when, at 36, she had to have an emergency hysterectomy and again eight  years later, when she had a second surgery. When the strange letter from the  water district arrived, Darlene says, ''I kept thinking back to his clothing,  to my hysterectomy. I asked myself, what does DuPont have to do with our  drinking water?'' 
         
        Joe called the West Virginia Department of Natural Resources  (''They treated me like I had the plague''), the Parkersburg office of the  state's Department of Environmental Protection (''nothing to worry about''),  the water division (''I got shut down''), the local health department (''just  plain rude''), even DuPont (''I was fed the biggest line of [expletive] anybody  could have been fed''), before a scientist in the regional E.P.A. office  finally took his call.
         
        ''Good God, Joe,'' the scientist said. ''What the hell is  that stuff doing in your water?'' He sent Kiger information about the Tennant  lawsuit. On the court papers Kiger kept seeing the same name: Robert Bilott, of  Taft Stettinius & Hollister, in Cincinnati.
         
        Bilott had anticipated suing on behalf of the one or two  water districts closest to Washington Works. But tests revealed that six  districts, as well as dozens of private wells, were tainted with levels of PFOA  higher than DuPont's own internal safety standard. In Little Hocking, the water  tested positive for PFOA at seven times the limit. All told, 70,000 people were  drinking poisoned water. Some had been doing so for decades.
         
        But Bilott faced a vexing legal problem. PFOA was not a  regulated substance. It appeared on no federal or state list of contaminants.  How could Bilott claim that 70,000 people had been poisoned if the government  didn't recognize PFOA as a toxin  -  if PFOA, legally speaking, was no different  than water itself? In 2001, it could not even be proved that exposure to PFOA  in public drinking water caused health problems. There was scant information  available about its impact on large populations. How could the class prove it  had been harmed by PFOA when the health effects were largely unknown?
         
        The best metric Bilott had to judge a safe exposure level  was DuPont's own internal limit of one part per billion. But when DuPont  learned that Bilott was preparing a new lawsuit, it announced that it would  re-evaluate that figure. As in the Tennant case, DuPont formed a team composed  of its own scientists and scientists from the West Virginia Department of  Environmental Protection. It announced a new threshold: 150 parts per billion.
         
        Bilott found the figure ''mind-blowing.'' The toxicologists  he hired had settled upon a safety limit of 0.2 parts per billion. But West  Virginia endorsed the new standard. Within two years, three lawyers regularly  used by DuPont were hired by the state D.E.P. in leadership positions. One of  them was placed in charge of the entire agency. ''The way that transpired was  just amazing to me,'' Bilott says. ''I suppose it wasn't so amazing to my  fellow counsel in West Virginia who know the system there. But it was to me.''  The same DuPont lawyers tasked with writing the safety limit, Bilott said, had  become the government regulators responsible for enforcing that limit.
         
        Bilott devised a new legal strategy. A year earlier, West  Virginia had become one of the first states to recognize what is called, in  tort law, a medical-monitoring claim. A plaintiff needs to prove only that he  or she has been exposed to a toxin. If the plaintiff wins, the defendant is  required to fund regular medical tests. In these cases, should a plaintiff  later become ill, he or she can sue retroactively for damages. For this reason,  Bilott filed the class-action suit in August 2001 in state court, even though  four of the six affected water districts lay across the Ohio border.
         
        Meanwhile the E.P.A., drawing from Bilott's research, began  its own investigation into the toxicity of PFOA. In 2002, the agency released  its initial findings: PFOA might pose human health risks not only to those  drinking tainted water, but also to the general public  -  anyone, for instance,  who cooked with Teflon pans. The E.P.A. was particularly alarmed to learn that  PFOA had been detected in American blood banks, something 3M and DuPont had  known as early as 1976. By 2003 the average concentration of PFOA in the blood  of an adult American was four to five parts per billion. In 2000, 3M ceased  production of PFOA. DuPont, rather than use an alternative compound, built a  new factory in Fayetteville, N.C., to manufacture the substance for its own  use.
         
        Bilott's strategy appeared to have worked. In September  2004, DuPont decided to settle the class-action suit. It agreed to install  filtration plants in the six affected water districts if they wanted them and  pay a cash award of $70 million. It would fund a scientific study to determine  whether there was a ''probable link''  -  a term that delicately avoided any  declaration of causation  -  between PFOA and any diseases. If such links  existed, DuPont would pay for medical monitoring of the affected group in  perpetuity. Until the scientific study came back with its results, class  members were forbidden from filing personal-injury suits against DuPont.
        
    A reasonable expectation, at this point, was that the lawyers would move on.  ''In any other class action you've ever read about,'' Deitzler says, ''you get  your 10 bucks in the mail, the lawyers get paid and the lawsuit goes away.  That's what we were supposed to do.'' For three years, Bilott had worked for  nothing, costing his firm a fortune. But now Taft received a windfall: Bilott  and his team of West Virginian plaintiff lawyers received $21.7 million in fees  from the settlement. ''I think they were thinking, This guy did O.K.,''  Deitzler says. ''I wouldn't be surprised if he got a raise.''
         
        Not only had Taft recouped its losses, but DuPont was  providing clean water to the communities named in the suit. Bilott had every  reason to walk away.
         
        He didn't.
         
        ''There was a gap in the data,'' Bilott says. The company's  internal health studies, as damning as they were, were limited to factory  employees. DuPont could argue  -  and had argued - that even if PFOA caused  medical problems, it was only because factory workers had been exposed at  exponentially higher levels than neighbors who drank tainted water. The gap  allowed DuPont to claim that it had done nothing wrong.
         
        Bilott represented 70,000 people who had been drinking  PFOA-laced drinking water for decades. What if the settlement money could be  used to test them? ''Class members were concerned about three things,'' Winter  says. ''One: Do I have C8 in my blood? Two: If I do, is it harmful? Three: If  it's harmful, what are the effects?'' Bilott and his colleagues realized they  could answer all three questions, if only they could test their clients. Now,  they realized, there was a way to do so. After the settlement, the legal team  pushed to make receipt of the cash award contingent on a full medical  examination. The class voted in favor of this approach, and within months,  nearly 70,000 West Virginians were trading their blood for a $400 check.
         
        The team of epidemiologists was flooded with medical data,  and there was nothing DuPont could do to stop it. In fact, it was another term  of the settlement that DuPont would fund the research without limitation. The  scientists, freed from the restraints of academic budgets and grants, had hit  the epidemiological jackpot: an entire population's personal data and infinite  resources available to study them. The scientists designed 12 studies,  including one that, using sophisticated environmental modeling technology,  determined exactly how much PFOA each individual class member had ingested.
         
        It was assured that the panel would return convincing  results. But Bilott could not predict what those results would be. If no  correlation was found between PFOA and illness, Bilott's clients would be  barred under the terms of the agreement from filing any personal-injury cases.  Because of the sheer quantity of data provided by the community health study  and the unlimited budget  -  it ultimately cost DuPont $33 million  -  the panel  took longer than expected to perform its analysis. Two years passed without  any findings. Bilott waited. A third year passed. Then a fourth, a fifth, a  sixth. Still the panel was quiet. Bilott waited.
         
        It was not a peaceful wait. The pressure on Bilott at Taft  had built since he initiated the class-action suit in 2001. The legal fees had  granted him a reprieve, but as the years passed without resolution, and Bilott  continued to spend the firm's money and was unable to attract new clients, he  found himself in an awkward position.
         
        ''This case,'' Winter says, ''regardless of how hugely  successful it ends up, will never in the Taft firm's mind replace what they've  lost in the way of legal business over the years.''
         
        The longer it took for the science panel to conduct its  research, the more expensive the case became. Taft continued to pay consultants  to interpret the new findings and relay them to the epidemiologists. Bilott  counseled class members in West Virginia and Ohio and traveled frequently to  Washington to attend meetings at the E.P.A., which was deciding whether to  issue advisories about PFOA. ''We were incurring a lot of expenses,'' Bilott  says. ''If the scientific panel found no link with diseases, we'd have to eat  it all.''
        
    Clients called Bilott to say that they had received diagnoses of cancer or that  a family member had died. They wanted to know why it was taking so long. When  would they get relief? Among those who called was Jim Tennant. Wilbur, who had  cancer, had died of a heart attack. Two years later, Wilbur's wife died of  cancer. Bilott was tormented by ''the thought that we still hadn't been able to  hold this company responsible for what they did in time for those people to see  it.''
         
        Taft did not waver in its support of the case, but the  strain began to show. ''It was stressful,'' Sarah Barlage, Bilott's wife, says.  ''He was exasperated that it was lasting a long time. But his heels were so dug  in. He's extremely stubborn. Every day that went by with no movement gave him  more drive to see it through. But in the back of our minds, we knew that there  are cases that go on forever.''
         
        His colleagues on the case detected a change in Bilott. ''I  had the impression that it was extremely tough on him,'' Winter says. ''Rob had  a young family, kids growing up, and he was under pressure from his firm. Rob  is a private person. He didn't complain. But he showed signs of being under  enormous stress.''
         
        In 2010, Bilott began suffering strange attacks: His vision  would blur, he couldn't put on his socks, his arms felt numb. His doctors  didn't know what was happening. The attacks recurred periodically, bringing  blurry vision, slurred speech and difficulty moving one side of his body. They  struck suddenly, without warning, and their effects lasted days. The doctors  asked whether he was under heightened stress at work. ''Nothing different than  normal,'' Bilott told them. ''Nothing it hadn't been for years.''
         
        The doctors ultimately hit upon an effective medication. The  episodes ceased and their symptoms, apart from an occasional tic, are under  control, but he still doesn't have a diagnosis.
         
        ''It was stressful,'' Bilott says, ''not to know what the  heck was going on.''
         
        In December 2011, after seven years, the scientists began to  release their findings: there was a ''probable link'' between PFOA and kidney  cancer, testicular cancer, thyroid disease, high cholesterol, pre-eclampsia and  ulcerative colitis.
         
        ''There was relief,'' Bilott says, understated nearly to the  point of self-effacement. ''We were able to deliver what we had promised to  these folks seven years earlier. Especially since, for all those years, DuPont  had been saying that we were lying, trying to scare and mislead people. Now we  had a scientific answer.''
         
        As of October, 3,535 plaintiffs have filed personal-injury  lawsuits against DuPont. The first member of this group to go to trial was a  kidney-cancer survivor named Carla Bartlett. In October, Bartlett was awarded  $1.6 million. DuPont plans to appeal. This may have ramifications well beyond  Bartlett's case: Hers is one of five ''bellwether'' cases that will be tried  over the course of this year. After that, DuPont may choose to settle with  every afflicted class member, using the outcome of the bellwether cases to  determine settlement awards. Or DuPont can fight each suit individually, a  tactic that tobacco companies have used to fight personal-injury lawsuits. At  the rate of four trials a year, DuPont would continue to fight PFOA cases until  the year 2890.
         
        DuPont's continuing refusal to accept responsibility is  maddening to Bilott. ''To think that you've negotiated in good faith a deal  that everybody has abided by and worked on for seven years, you reach a point  where certain things were to be resolved but then remain contested,'' he says.  ''I think about the clients who have been waiting for this, many of whom are  sick or have died while waiting. It's infuriating.'' 
         
        As part of its agreement with the E.P.A., DuPont ceased  production and use of PFOA in 2013. The five other companies in the world that  produce PFOA are also phasing out production. DuPont, which is currently  negotiating a merger with Dow Chemical, last year severed its chemical  businesses: They have been spun off into a new corporation called Chemours. The  new company has replaced PFOA with similar fluorine-based compounds designed to  biodegrade more quickly  -  the alternative considered and then discarded by  DuPont more than 20 years ago. Like PFOA, these new substances have not come  under any regulation from the E.P.A. When asked about the safety of the new  chemicals, Chemours replied in a statement: ''A significant body of data  demonstrates that these alternative chemistries can be used safely.''
         
        Last May, 200 scientists from a variety of disciplines  signed the Madrid Statement, which expresses concern about the production of  all fluorochemicals, or PFASs, including those that have replaced PFOA. PFOA  and its replacements are suspected to belong to a large class of artificial  compounds called endocrine-disrupting chemicals; these compounds, which include  chemicals used in the production of pesticides, plastics and gasoline,  interfere with human reproduction and metabolism and cause cancer, thyroid  problems and nervous-system disorders. In the last five years, however, a new  wave of endocrinology research has found that even extremely low doses of such  chemicals can create significant health problems. Among the Madrid scientists'  recommendations: ''Enact legislation to require only essential uses of PFASs''  and ''Whenever possible, avoid products containing, or manufactured using,  PFASs. These include many products that are stain-resistant, waterproof or  nonstick.''
         
        When asked about the Madrid Statement, Dan Turner, DuPont's  head of global media relations, wrote in an email: ''DuPont does not believe  the Madrid Statement reflects a true consideration of the available data on  alternatives to long-chain perfluorochemicals, such as PFOA. DuPont worked for  more than a decade, with oversight from regulators, to introduce its  alternatives. Extensive data has been developed, demonstrating that these  alternatives are much more rapidly eliminated from the body than PFOA, and have  improved health safety profiles. We are confident that these alternative chemistries  can be used safely  -  they are well characterized, and the data has been used to  register them with environmental agencies around the world.''
         
        Every year Rob Bilott writes a letter to the E.P.A. and the  West Virginia D.E.P., urging the regulation of PFOA in drinking water. In 2009,  the E.P.A. set a ''provisional'' limit of 0.4 parts per billion for short-term  exposure, but has never finalized that figure. This means that local water  districts are under no obligation to tell customers whether PFOA is in their  water. In response to Bilott's most recent letter, the E.P.A. claimed that it  would announce a ''lifetime health advisory level for PFOA'' by ''early 2016.''
         
        This advisory level, if indeed announced, might be a source  of comfort to future generations. But if you are a sentient being reading this  article in 2016, you already have PFOA in your blood. It is in your parents'  blood, your children's blood, your lover's blood. How did it get there? Through  the air, through your diet, through your use of nonstick cookware, through your  umbilical cord. Or you might have drunk tainted water. The Environmental  Working Group has found manufactured fluorochemicals present in 94 water  districts across 27 states (see sidebar beginning on Page 38). Residents of Issaquah,  Wash.; Wilmington, Del.; Colorado Springs; and Nassau County on Long Island are  among those whose water has a higher concentration of fluorochemicals than that  in some of the districts included in Rob Bilott's class-action suit. The  drinking water in Parkersburg itself, whose water district was not included in  the original class-action suit and has failed to compel DuPont to pay for a  filtration system, is currently tainted with high levels of PFOA. Most  residents appear not to know this.
         
        Where scientists have tested for the presence of PFOA in the  world, they have found it. PFOA is in the blood or vital organs of Atlantic  salmon, swordfish, striped mullet, gray seals, common cormorants, Alaskan polar  bears, brown pelicans, sea turtles, sea eagles, Midwestern bald eagles,  California sea lions and Laysan albatrosses on Sand Island, a wildlife refuge  on Midway Atoll, in the middle of the North Pacific Ocean, about halfway  between North America and Asia.
         
        ''We see a situation,'' Joe Kiger says, ''that has gone from  Washington Works, to statewide, to the United States, and now it's everywhere,  it's global. We've taken the cap off something here. But it's just not DuPont.  Good God. There are 60,000 unregulated chemicals out there right now. We have  no idea what we're taking.''
         
        Bilott doesn't regret fighting DuPont for the last 16 years,  nor for letting PFOA consume his career. But he is still angry. ''The thought  that DuPont could get away with this for this long,'' Bilott says, his tone  landing halfway between wonder and rage, ''that they could keep making a profit  off it, then get the agreement of the governmental agencies to slowly phase it  out, only to replace it with an alternative with unknown human effects  -  we  told the agencies about this in 2001, and they've essentially done nothing.  That's 14 years of this stuff continuing to be used, continuing to be in the  drinking water all over the country. DuPont just quietly switches over to the  next substance. And in the meantime, they fight everyone who has been injured  by it.''
  
  
        
        Bilott is currently prosecuting Wolf v. DuPont, the second  of the personal-injury cases filed by the members of his class. The plaintiff,  John M. Wolf of Parkersburg, claims that PFOA in his drinking water caused him  to develop ulcerative colitis. That trial begins in March. When it concludes,  there will be 3,533 cases left to try.
  
  
         
        Correction: January 24, 2016
        An article on Jan 10. about legal action against DuPont for  chemical pollution referred incorrectly to DuPont's response in the 1970s when  the company discovered high concentrations of PFOA in the blood of workers at  Washington Works, a DuPont factory. DuPont withheld the information from the  E.P.A., not from its workers. The article also misstated the year DuPont agreed  to a $16.5 million settlement with the E.P.A. It was 2005, not 2006. In  addition, the article misidentified the water district where a resident  received a letter from the district noting that PFOA had been detected in the  drinking water. It was Lubeck, W.Va. — not Little Hocking, Ohio. The article  also misidentified the district where water tested positive for PFOA at seven  times the limit. It was Little Hocking, not Lubeck. And the article  misidentified the city in Washington State that has fluorochemicals in its  drinking water. It is Issaquah, not Seattle.
  
  New York Times