A federal appeals court has thrown out a $785,000 award to a woman who blamed her mother's cancer death on contamination from a wood treatment plant in Mississippi, one of hundreds of such cases against the facility's owner.

The 5th U.S. Circuit Court of Appeals in New Orleans ruled Monday that the state's three-year statute of limitations barred Kenesha Barnes' claim against Koppers Inc. and Beazer East Inc.

After a three-week trial in 2006, a jury found the companies liable for negligently exposing Barnes' mother, Sherrie, to harmful chemicals from the Grenada plant, which treats railroad crossties and utility poles with creosote and other chemicals.

Sherrie Barnes, who lived next to the plant her entire life, died about a year after she was diagnosed with breast cancer in June 1997. More than five years elapsed between her diagnosis and the date in 2003 when Kenesha Barnes filed a wrongful death suit on her mother's behalf.

A three-judge panel from the 5th Circuit said the companies raised "troubling questions" about how the case was handled by U.S. District Judge W. Allen Pepper Jr., including his decisions on the admission of expert testimony.