EAST ST. LOUIS - Chief U.S. District Judge Nancy Rosenstengel excluded epidemiologist Martin Wells from a witness stand where he alone would have testified that weed killer paraquat causes Parkinson’s disease.
She granted summary judgment to paraquat producer Syngenta and former producer Chevron on April 17, and she dismissed four plaintiffs she had selected for trials.
“His proffered opinion required several methodological contortions and outright violations of the scientific standards he professed to apply,” she wrote.
“Dr. Wells redefined occupational exposure no less than three times, creating more questions than answers about the types of paraquat exposures that according to him can cause Parkinson’s disease,” she added.
She found methodological deficiencies suggested he failed to apply the intellectual rigor that would be required of him and his peers outside of litigation.
She ordered plaintiff leaders to nominate eight candidates for trial replacements and ordered Syngenta and Chevron to nominate four each.
Rosenstengel presides over more than 5,000 suits from district courts in many states by appointment of a judicial panel in Washington.
She held four days of hearings on experts in August with Wells testifying for two days about his meta analysis, a study of studies back to 1997.
She found meta analysis allows a researcher to pool results of many studies with a goal of arriving at a numerical risk estimate that represents the totality of the studies.
“Dr. Wells’ violations of the rules of meta analysis are evident from the very beginning of his process,” she wrote.
Rosenstengel found an initial step involves a search for relevant studies that are further analyzed for potential inclusion.
“Dr. Wells’ first report is entirely devoid of a search narrative that would allow other researchers to validate his process,” she wrote.
Rosenstengel said he listed 11 case control studies that were supposedly included.
She found Wells explained that he reviewed the five most recent systematic reviews on the relationship between paraquat and Parkinson’s disease.
Then his later report in rebuttal to a defense report identified 36 studies that he claimed he considered for inclusion.
Rosenstengel found Wells failed to explain how he identified them and couldn’t remember details about how he searched for and identified them.
“As a result, any attempt to replicate his search for relevant literature would require a degree of clairvoyance that this court does not possess,” she wrote.
She found his unwritten approach freed him to select studies he wanted to analyze and justify his selections based on results.
Rosenstengel found his failure to define eligibility criteria in advance suggested he selected studies he wanted and crafted criteria to justify his decisions.
“This is the antithesis of systematic review which relies on predefined eligibility criteria to ensure transparency and scientific objectivity,” she wrote.
She proceeded to the heart of the matter: exposure.
“Wells offers an expert opinion that occupational exposure is causally related to Parkinson’s disease,” she wrote.
“Any exposure that does not qualify as occupational is therefore not within the scope of his opinion,” she added.
“So, what is occupational exposure? The record reveals a strikingly amorphous definition of this term,” she concluded.
Rosenstengel found his first report appeared to define it by distinguishing it from community exposure.
“Yet his first report does not define community exposure, leaving one to speculate as to how long, in what quantities, in what frequency, or in what setting an exposure must occur to cause Parkinson’s disease,” she wrote.
She found he testified at a deposition that occupational exposure meant it was primarily focused on people’s work and exposure.
She found he changed course in his rebuttal report, stating occupational exposure involved use of paraquat or contact where there was a risk of dermal exposure.
She added that his rebuttal report defined occupational exposure as “related to the use of paraquat or contact with paraquat where there is the risk of dermal exposure.”
“Of course, this revised objective no longer distinguished between workplace and residential exposure studies,” she wrote.
Rosenstengel found Wells insisted he had credentials to do this and he had a process that he followed.
“But these assurances, without more, do not show that Dr. Wells faithfully applied the necessary steps of his chosen methodology,” she wrote.
“If anything, it shows the opposite,” she added.
She dismissed trial plaintiffs Frederick Richter of Effingham County, Keith Fuller of Adams County, Todd Burgener of Macon County, and Matthew Conrad of Florida.
Chad Finley of Tor Hoerman’s firm in Edwardsville represents Burgener and Troy Walton of Walton Telken in Edwardsville represents Richter.
LaRuby May of Alabama represents Conrad and Leslie LaMacchia of Florida represents Fuller.
Rosenstengel set a May 10 deadline for nominating replacements.
She wrote that she’d issue a discovery schedule and trial dates.