Striking a blow to toxic tort plaintiffs who rely on estimates, as opposed to actual data, the Iowa Court of Appeals found that expert testimony relying on such “exposure estimates” was insufficient to prove causation of birth injuries associated with use of a pesticide. See Junk v. Obrecht, No. 3-454 (Iowa Ct. App. Sept. 5, 2013), available at www.bdlaw.com/assets/attachments/junkvobrecht.pdf.

Plaintiffs, Rene Junk and her husband, hired Terminex International Company to treat their home for the presence of spiders while Ms. Junk was pregnant. Junk, slip op. at 2. Over a period of three years, Terminex employees sprayed the inside of Junk’s home with the pesticide Dursban. Id. In 1992, the Junks’ son, Tyler, was born with physical, neurological, and psychological impairments.Id. In 2005, Plaintiffs sued Terminex, two Terminex employees, Dow Chemical Company, and Dow AgroSciences alleging that exposure to chloropyrifos, a chemical in Dursban, caused their son’s defects. Id.

Plaintiffs’ key expert, Dr. Richard Fenske, used an “exposure estimates” methodology to substantiate his conclusion that while it was unknown how much chlorpyrifos the Junks’ son had been exposed to, exposure levels likely exceeded recommended EPA levels. Id. The other experts had relied on Dr. Fenske’s “exposure estimates” to form their own conclusions. Id.

Arguing that the “exposure estimates” were unreliable, Defendants moved to exclude the testimony in the federal court. Id. Using the analysis set out in Daubert v. Merrill Dow Pharmaceuticals, Inc., 509 U.S. 579, 591-95 (1993) to determine whether scientific testimony is admissible, the court determined that Dr. Fenske had not applied a scientifically reliable methodology in estimating exposure levels and granted Defendants’ subsequent motion for summary judgment. Id. at 3-4. The Eighth Circuit affirmed this ruling, finding that Dr. Fenske’s conclusions were based on “unfounded assumptions.” Id. However, the court remanded the action to state court for proceedings against the Terminex employees. Id. at 5.

Both Dr. Fenske and another expert filed new affidavits while the case was on remand, stating that they agreed with Fenske’s first affidavit. Id. Defendants again moved for summary judgment on the basis that the expert testimony should be excluded, and the Iowa lower court granted the motion. Id.The Iowa Court of Appeals affirmed the court’s decision, finding, like the Eighth Circuit, that Dr. Fenske’s opinion failed to meet the scientific reliability standard set out in Daubert and that the opinions of the other experts, which relied on Dr. Fenske’s report, were likewise unreliable. Id. at 6-12.