Opinion ID: 772445
Heading Depth: 4
Heading Rank: 2

Heading: Kilburn's Methodology

Text: 26 In examining the scientific validity of the methodology Kilburn used to conclude that the plaintiffs were injured as a result of exposure to PCBs, the magistrate judge focused most heavily upon Kilburn's failures to account for confounding factors that could have caused similar symptoms, establish a temporal relationship between exposure to PCBs in Lobelville and the reported maladies, demonstrate that the plaintiffs received doses of PCBs sufficient to make them ill, or show that his theories enjoyed general acceptance. We agree that the flaws in the methodology underlying Kilburn's opinion that PCB exposure caused the plaintiffs' impairments, as well as a lack of support for the proposition that environmental PCB exposure can cause the impairments Kilburn found in the Lobelville subjects, render his opinion unreliable. 27 With respect to the question of dose, plaintiffs cannot dispute that Kilburn made no attempt to determine what amount of PCB exposure the Lobelville subjects had received and simply assumed that it was sufficient to make them ill. On appeal, plaintiffs argue only that because PCBs were present in the environment in excess of allowable limits and plaintiffs lived and worked in the area, they must have been exposed at a level that could cause neurological and lung impairments. 8 This is a significant flaw in Kilburn's methodology as his cohort epidemiological study seeks to demonstrate a relationship between exposure and disease by comparing those who have been exposed with those who have not. Without any factual basis from which a jury could infer that the plaintiffs were in fact exposed to PCBs from Station 79, the reasoning and methodology underlying the testimony is not scientifically valid. See, e.g., Conde v. Velsicol Chem. Corp., 24 F.3d 809 (6th Cir. 1994) (chlordane exposure). This defect goes hand-in-hand with the failure to evaluate or show a temporal relationship between exposure and symptoms, which is most glaringly illustrated by evidence that some of the flagship plaintiffs experienced cognitive impairments and mood disorders before ever moving to Lobelville. 28 The magistrate judge carefully analyzed the question of whether Kilburn considered and accounted for confounding factors which could be responsible for the impairments and health problems found in the plaintiffs. Without contesting any specific findings, plaintiffs assert that Kilburn's statistical analysis accounted for any significant confounding factors. 9 29 Plaintiffs explain the statistical analysis as follows. The ninety-eight Lobelville subjects and the fifty-eight unexposed referents completed questionnaires and were subjected to a battery of tests intended to detect neurological and pulmonary abnormalities. The results were given numerical values, and the abnormal scores were compiled. When the total score reached a certain level of significance, Kilburn concluded that those ill effects were, more probably than not, caused by PCB exposure. This kind of cohort epidemiological study hopes to establish an association between exposure and disease, but an association does not mean there is a cause and effect relationship. See Reference Manual on Scientific Evid. 333, 348 (2d ed. 2000). Before any inferences are drawn about causation, the possibility of other reasons for the association must be examined, including chance, biases such as selection or informational bias, and confounding causes. Id. at 354. 30 Even if this methodology validly showed that plaintiffs were impaired (which defendants do not concede), it did not provide a valid scientific basis for the opinion on causation. As Kilburn admitted, these tests could not identify what caused the impairments, and there were a number of other possible causes or confounding factors. He testified that alcohol was the most common cause of what he characterized as encephalopathy and cigarette smoking the most common cause of airway obstruction. He also testified that the symptoms could be caused by drug use, living in mobile homes, exposure to chemicals in solvents and spray paints, and working with textiles. As the magistrate judge found, the record is replete with evidence of other factors or agents which, according to Dr. Kilburn's own testimony, may have been responsible for the symptoms suffered by the flagship plaintiffs - evidence which, it appears, Dr. Kilburn utterly ignored. We agree with the magistrate judge that there was simply no basis for Dr. Kilburn's assumption that PCBs, and not one of numerous other factors, was the cause of plaintiffs' reported maladies. 31 Without any citation to the record, plaintiffs claim next that Kilburn actually included the thirty-three members of the Mormon Church from Waverly, Tennessee, in the Tennessee control group in order to account for the confounding factors of alcohol use, drug abuse, and cigarette smoking since such activities are discouraged by the church. There is no indication in the record, however, that Kilburn included this group of referents for this purpose, or that he analyzed the data to account for such factors. 32 While plaintiffs assert generally that there are commonly observed symptoms of PCB exposure documented in the scientific literature, Kilburn actually admitted that no scientific literature supports his opinion that PCBs can cause the brain disorder he refers to as encephalopathy. Indeed, plaintiffs do not specifically contest any of the findings concerning the lack of general acceptance for Kilburn's theory that PCBs can cause the kind of symptoms identified in the Lobelville plaintiffs. Shifting focus, plaintiffs claim instead that the battery of tests he used are generally accepted as a means of measuring neurological impairment. Even assuming that this were true, that does not demonstrate the scientific validity of the methodology used to conclude that PCBs caused the injuries reflected by the results of those tests. 33 As the Court in Daubert stated, the inquiry must be solely on principles and methodology, not on the conclusions that they generate. 509 U.S. at 595. However, as the Court later clarified, conclusions and methodology are not entirely distinct from one another. Joiner, 522 U.S. at 146. A district court is not required to admit expert testimony that is connected to existing data only by the ipse dixit of the expert. A court may conclude that there is simply too great an analytical gap between the data and the opinion proffered. Id. The magistrate judge did not abuse his discretion by finding that Kilburn's testimony presented just such a case.