Smoke Over Iberia Parish
On June 14, 2011, a fire broke out at the Multi-Chem Group facility in Iberia Parish, Louisiana. It set off a series of explosions. The facility held 700,060 gallons of chemicals at the time. Witnesses saw drums and containers flying into the air.
Authorities evacuated a one-mile area. By varying accounts, the fire burned for 22 to 24 hours. Workers at neighboring businesses and nearby residents later sued, alleging that smoke and wind carried hazardous materials to them.
The question at trial was not whether Multi-Chem was liable. That had been settled before trial. The question was whether the smoke could cause the burning eyes, headaches and nosebleeds the plaintiffs described, and whether it did. That is a toxicology question.
Toxicologists study how chemicals harm the human body. In court, they explain what a substance can do at a given level of exposure. They explain what a blood or urine test does and does not show, and whether a person's symptoms fit an exposure. Judges and juries hear from them because those answers depend on chemistry, pharmacology and the published science, not on common experience.
The five rulings below come from three trial courts and two appellate courts. Each shows what a court accepted when a toxicologist's work was challenged.
Where Toxicologists Appear in Litigation
A maintenance worker died in an underground fuel tank sump at an Oklahoma gas station. Residents near a Mississippi wood treatment plant claimed that creosote from the plant caused breast cancer and other illness. A carpenter fell 12 feet at a North Carolina job site and tested positive for cannabinoids. A truck driver with morphine, Xanax and methadone in his blood rear-ended a car in Philadelphia. Workers and residents near the Louisiana chemical fire claimed injury from the smoke.
The cases were wrongful death, environmental exposure, workers' compensation, motor vehicle negligence and industrial accident claims. The toxicologists in them answered three kinds of questions.
The first was causation. Courts ask whether a substance can cause the harm alleged, which is general causation. They also ask whether it caused this plaintiff's harm, which is specific causation.
The second was impairment. The question was whether a drug in a person's system affected judgment or driving at the moment that mattered.
The third was what a test result means. A postmortem blood sample, a hospital urine screen and an air monitor reading each have limits. Toxicologists told the courts what those limits were.
The challenges followed familiar lines. Opponents attacked qualifications. One argued that a medical toxicologist could not interpret postmortem samples without a forensic certification. Another argued that an expert whose work centered on products regulated by the Food and Drug Administration could not speak to an industrial fire.
They attacked the data. Postmortem results were called inconclusive. Air sampling was said to show no hazardous chemicals above regulatory levels. A toxicology report was said to be conditional.
They attacked dose. In two cases, the defense argued that the plaintiffs could not show how much of a chemical reached them, or for how long.
The Cases
Adams v. E-Z Mart Stores: Postmortem Toxicology Clears the Gate
Adams v. E-Z Mart Stores, Inc., United States District Court for the Eastern District of Oklahoma, Case No. 23-CV-278-RAW. Order entered January 22, 2026.
Lonnie Adams worked for a maintenance company. He died while working at an E-Z Mart gas station in a six-foot-deep underground tank sump. His widow, Ashley Adams, sued E-Z Mart for wrongful death. She alleged that E-Z Mart failed to warn him of the risk the fuel sump posed.
The medical examiner's autopsy report listed five diagnoses. They included asphyxia due to vitiated atmosphere, and methamphetamine and ethanol toxicity.
Defendant retained a medical toxicologist to explain what the toxicology results meant. He was Medical Director of the Oklahoma Center for Poison Control and Drug Information. He held an M.D. and a Ph.D. in pharmacology, completed a fellowship in clinical pharmacology, and was board certified in medical toxicology. He had a long history with the American Association of Poison Control Centers, the American Academy of Clinical Toxicology and the American Board of Medical Toxicology.
His report addressed the cause of death. It explained how methamphetamine use may have contributed by causing both impairment and underlying cardiac weakness. He addressed postmortem redistribution, the accuracy of the test used to detect methamphetamine and where the blood samples came from. He relied on his expertise and on peer-reviewed research.
Plaintiff moved to exclude him and the toxicology report. She argued that postmortem samples required a forensic toxicologist. She called the findings inconclusive and argued that his opinions were speculative and prejudicial.
Judge Ronald A. White denied both motions. The Court found him qualified by training and experience. His board certification in medical toxicology was sufficient credentialing, the Court held, even without a specific certification in forensic toxicology.
The Court found the toxicology findings admissible, so his reliance on them did not make his opinions unreliable. Questions about methamphetamine isomers and what the results showed about the decedent's health or impairment were within his expertise. Plaintiff's experts disagreed with him, but the Court held that disagreement did not make his opinions inadmissible. It quoted the Tenth Circuit: "Establishing reliability does not require showing that the expert's testimony is 'indisputably correct.'"
The Court also rejected the argument that his opinion on poor judgment was an improper legal conclusion. He tied that opinion to clinical studies. The postmortem concentrations were consistent with those of people who showed impaired judgment in those studies. Framed that way, it was not an impermissible opinion on an ultimate issue under Rule 704.
Whitfield v. Tronox Worldwide: A Battle of the Experts Over Creosote
Whitfield v. Tronox Worldwide LLC, United States District Court for the Northern District of Mississippi, Eastern Division, Lead Case No. 1:03CV287-D-D. Opinion entered July 23, 2007.
The plaintiffs owned property near, or had lived near, a closed wood treatment plant in Columbus, Mississippi. For decades, the 90-acre plant had treated railroad crossties with coal tar creosote, injecting it into the wood under pressure. Plaintiffs alleged that the process contaminated groundwater and released vapors, mists and dust into the community.
The first trial was set for November 5, 2007. One of the two first-trial plaintiffs claimed breast cancer. She was 52 and had lived her entire life about half a mile west of the plant.
Plaintiffs' toxicologist was board certified. She was a tenured Professor of Toxicology at the University of New Orleans and coordinated toxicology research laboratories at the Pontchartrain Institute for Environmental Sciences. She held a Ph.D. in anatomy from Tulane, with a minor in biochemistry. She had been a Professor of Medicine at the Louisiana State University Medical School in Shreveport and directed its Occupational Toxicology Outreach Program.
She opined that creosote released from the plant caused or worsened the plaintiffs' injuries. Defendants did not challenge her qualifications. They argued that she had not shown the plaintiff was exposed to enough creosote to cause breast cancer. They also attacked her method and said her analysis did not support her conclusion.
Judge Glen H. Davidson held two days of hearings beginning June 18, 2007. The defense expert admitted that reasonable, qualified toxicologists can differ on methods and study parameters.
The parties disputed which breast cancer prevalence rate she should have used, 79.3 or 151.5 per 10,000. The Court left that for cross-examination. Her report cited nearly 180 sources. The defense expert criticized seven of them, and the Court left that for the jury too.
The Court called her "clearly and indisputably well-qualified." It found that her extensive report appeared to rest on reliable methodology. She had testified at length about the strength of the association between dioxins, such as those in creosote, and breast cancer. She had also considered confounders, including birth control pills and another nearby industrial facility.
The Court denied the motion. It described the dispute as a classic battle of the experts, "where the jury will decide which witness' testimony is more credible." In the same opinion, the Court allowed the testimony of Plaintiffs' epidemiologist and a statistical analysis performed at the toxicologist's request.
Moore v. Sullbark Builders: Testing the Test
Moore v. Sullbark Builders, Inc., Court of Appeals of North Carolina, No. COA08-1348. Opinion filed August 4, 2009.
Jamie Moore worked as a trim carpenter. On December 7, 2005, he was carrying two-by-twelve boards on his shoulders when his ankle twisted. He fell about 12 feet to the bottom of a retaining wall. He suffered a thoracic spine fracture and a pulmonary contusion.
At the hospital, a urine screen tested for ethanol and six drugs. It came back positive for cannabinoids and opiates. The report gave no levels or concentrations, and no confirmatory test was run.
His employer denied the workers' compensation claim. It relied on a North Carolina statute that bars compensation when an injury was caused by being under the influence of a controlled substance. A test result can create a rebuttable presumption of impairment, but only if the test was conducted in a manner generally acceptable to the scientific community. The employer bore the burden of proof.
Two toxicologists testified by deposition. The one whose testimony Plaintiff presented told the Industrial Commission that "it's well recognized in the scientific community, urine tests cannot be used to establish impairment." He supported that with ten quotations from forensic toxicology literature.
He testified that marijuana's psychoactive effects usually last up to four hours. Both toxicologists agreed that the hospital test was done for medical purposes only and was not valid for forensic use. The hospital's own record warned that unconfirmed results should not be used for nonmedical purposes.
The Commission found that the result did not create a presumption of impairment. Even if it had, the Commission concluded, Plaintiff's toxicology testimony rebutted it. Coworkers confirmed he had not used marijuana during the workday. The Commission found that the fall resulted from a misstep and a railing that gave way. It awarded temporary total disability compensation.
The Court of Appeals affirmed. Judge Bryant wrote that the Commission, as sole judge of credibility, had discretion to find his opinion more credible than the conflicting opinion of the other toxicologist. The test results showed only that marijuana was in the worker's system. They did not show impairment at the time of the injury.
Donaldson v. Arsenich: Blood Levels and a Verdict for Plaintiffs
Donaldson v. Arsenich, Court of Common Pleas of Philadelphia County, Civil Trial Division, Nos. 1006 and 3390. Memorandum opinion of March 10, 2011.
On March 8, 2007, Vincent James was stopped at a red light at Cheltenham and Ogontz Avenues. Eva Donaldson's car hit the rear of his van after a white truck struck her car from behind. John Arsenich was driving the truck while working. The Plaintiffs sued him and Future Tire of Philadelphia.
The responding officer saw no obvious signs of impairment. Because Arsenich drove a commercial vehicle, he had to submit to a blood test. He told the officer he was on no medications.
A toxicologist tested the blood for the police. At trial, he testified for Plaintiffs. He found 38 nanograms of morphine and 13 nanograms of Xanax per milliliter. He also found methadone. Arsenich had no prescription for any of them.
His conclusion was conditional. He stated that "it can be stated with reasonable scientific certainty" that if the driver showed signs of impairment, such as erratic driving or unusual demeanor, these substances could be responsible. Arsenich later testified that he had used heroin and methadone before the crash. He had pleaded guilty to driving under the influence.
Defendants moved before trial to exclude the drug evidence. The Court denied the motions. Trial began on May 24, 2010. On June 7, 2010, the jury returned verdicts of $520,000 for James and $800,000 for Donaldson, reduced by 3% for her own negligence.
On post-trial motions, Defendants argued that the toxicologist had testified to impairment with no other evidence of it. His report, they said, required signs of impairment that no one had observed. They also argued that the morphine level fell in the therapeutic range.
Judge Overton rejected each point. Under the law the Court applied, toxicology results alone are not admissible in a civil trial. There must also be corroborating evidence of impairment. Here, the driver failed to react to traffic stopped at a red light at an intersection he knew. He admitted in deposition that he became distracted. The jury could reasonably infer impairment.
On the therapeutic range, the Court pointed to the toxicologist's own testimony. That range applies only when the drug is taken therapeutically with a prescription, and there was none. The Court denied a new trial and remittitur. The Superior Court affirmed without opinion on October 26, 2011.
Broussard v. Multi-Chem Group: General Causation From Imperfect Data
Broussard v. Multi-Chem Group, LLC, Court of Appeal of Louisiana, Third Circuit, No. 17-985, consolidated with Nos. 17-986 through 17-992. Decided July 11, 2018.
After the 2011 fire, the consolidated cases went to a multi-day bench trial on causation and damages. The parties chose twelve bellwether plaintiffs from three groups, sorted by distance from the fire: under one mile, one to three miles, and over three miles.
Plaintiffs' expert was a board-certified toxicologist and pharmacologist. She held a Ph.D. in pharmacology and had been a fellow with the National Institutes of Health. She had been an assistant professor at the University of Arkansas for Medical Sciences, with appointments in pharmacology and toxicology. She had run her own consulting company in Houston since 1997 and listed thirty-three publications.
She testified that air sampling showed particulate matter for days after the fire, at levels above regulatory standards. The sampling measured volatile chemicals but not chemicals absorbed into the particles. The plaintiffs' acute symptoms, she said, were consistent with exposure to that particulate matter. Some of the chemicals involved were potential carcinogens.
She did not perform a dose and duration analysis for each plaintiff. She explained that monitoring was not done where people lived, and that there was no good data for the first seven hours of the fire. She testified that such an analysis was not necessary for her opinion, given the elevated levels that were measured.
Defendants argued that she was unqualified because much of her work involved products regulated by the Food and Drug Administration. They argued that she misread air data collected by their own expert.
The trial court found her testimony reliable after considering testability, peer review and publication, and general acceptance. It made no such finding for the defense toxicologist. It adopted her opinion as a finding of fact. The plaintiffs with symptoms, it found, were more probably than not exposed in sufficient dose and duration to cause their injuries. It awarded damages to all twelve bellwether plaintiffs.
Judge Marc T. Amy wrote for the Court of Appeal. Her experience supported the qualification ruling, including her past work on industrial fires. Defendants' reliability argument depended on accepting their own expert's criticisms, which the trial court had not credited. "We leave the trial court's consideration of that testimony undisturbed," the Court wrote.
The Court also noted that the air data had been generated under Defendants' direction and control. It upheld the findings of general and specific causation. It affirmed the general damages awards for all twelve plaintiffs. It reversed five awards for fear of developing cancer because those plaintiffs had not testified to that fear. The Louisiana Supreme Court denied review on November 14, 2018.
What the Rulings Have in Common
Four of the five experts held doctorates, and the records describe three as board certified. Qualification fights turned on fit, not degrees. In Oklahoma, a board certification in medical toxicology sufficed for postmortem work. In Louisiana, a toxicologist whose practice centered on regulated products was qualified to address an industrial fire because she had worked on similar fires before.
The courts looked at method, not outcome. The accepted methods were the ordinary tools of the field. They included peer-reviewed literature, published studies on dose and effect, regulatory standards, and attention to confounders.
The experts also explained the limits of their data instead of ignoring them. The Oklahoma expert addressed postmortem redistribution and sample source. The Louisiana expert explained why air data could not support a dose estimate for each person. The North Carolina expert showed why a urine screen without concentrations could not prove impairment.
Disagreement did not defeat admission. In Oklahoma, opposing experts disagreed, and the Court sent that to cross-examination. In Mississippi, the Court called the dispute a battle of the experts. In Louisiana and North Carolina, the fact finders chose between two toxicologists, and the appellate courts deferred to those choices.
Fit came down to how opinions were framed. The Oklahoma opinion on judgment rested on clinical studies of comparable concentrations, so it was not a legal conclusion. The Philadelphia opinion was conditional, and the Court tied it to evidence of how the crash happened.
Practical Points for Attorneys
Impairment opinions held up when they were anchored to something outside the test. In Oklahoma, the anchor was clinical studies of comparable concentrations. In Philadelphia, it was the crash itself: a driver who failed to stop for traffic at an intersection he knew. The Court required that kind of corroboration before the blood results could come in at all.
The test itself is fair ground. The North Carolina worker's case rested on a toxicologist who explained what a medical urine screen cannot show. That testimony defeated a statutory presumption the employer relied on.
Where data are thin, an expert can say so and still be heard. The Louisiana court accepted a causation opinion built on imperfect monitoring. It noted that the party challenging the data had controlled its collection. Louisiana law allowed exposure to be shown by a qualitative assessment as well as a quantitative one.
A detailed record of sources helps. In Mississippi, the expert cited nearly 180 sources, and the defense challenged seven. The Court treated those criticisms as matters for the jury.
Credentials should match the precise question. The Oklahoma plaintiff argued that only a forensic toxicologist could read postmortem results, and that the defense expert worked only with live patients. The Court found that claim contradicted by the record and held his medical toxicology certification enough.
Deadlines still matter. In Oklahoma, the defense argued that the motions to exclude were untimely. The Court reached the merits only because of a delay in deposition errata sheets and similar motions filed in the earlier state court case.
The Record Across Five Courts
Between 2007 and 2026, courts in five states reviewed the work of the five toxicologists featured here. Plaintiffs called four of them. A defendant retained one.
Their work ranged from postmortem blood and hospital urine screens to creosote studies and air sampling after a chemical fire. Each court allowed the testimony. In two of the cases, the fact finder relied on it directly.
In three of the cases, the side that called the toxicologist then prevailed. The North Carolina worker received compensation. The Philadelphia plaintiffs won jury verdicts. The Louisiana bellwether plaintiffs received damages, which the Court of Appeal largely affirmed.
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