Expert’s Opinion Calculating Benzene Exposure Tossed As Unreliable

Last Thursday, the U.S. District Court for the Eastern District of Louisiana excluded the plaintiff’s proposed expert in an alleged benzene exposure case on the grounds that his methodologies used for calculating benzene exposure were unreliable.  The plaintiff was the surviving spouse of an individual who had worked as a gas station attendant from 1958 to 1971 and had died from leukemia in 2013.  To establish exposure to benzene, plaintiff relied on an industrial hygienist to provide an estimate of the worker’s cumulative benzene exposure from gasoline while working at one particular gas station over a one-year period between 1966 and 1968.  The expert considered four separate potential exposure sources:  inhaling vapors that evaporated from the parts-washing bucket containing gasoline during the winter months when the gas station’s garage doors were closed; dermal exposure from washing parts in a bucket of gasoline; dermal exposure resulting from gasoline soaking parts of the worker’s clothing; and inhaling vapors while washing parts in gasoline.  The expert opined that the worker’s cumulative dose of benzene was 61.678 ppm throughout the time while working at this particular service station.

The court concluded that the expert’s opinions were unreliable.  The expert’s estimate of the amount of exposure from inhaling gasoline evaporated from the parts-washing bucket while the garage doors were closed, for example,  would have been high enough to have been lethal within a matter of minutes.  The expert even cited a study that showed that exposure to as little as 5,000 ppm gasoline for six minutes can be lethal, but failed to reconcile that with his assumption that the worker was exposed to a concentration of 8,449 ppm gasoline for hundreds of hours over the course of a year.  As the court explained, “Even though [the expert] has now withdrawn his calculation, that he chose the methodology and included the findings in his report remains relevant because it informs the Court about [the expert’s] overall approach to choosing and analyzing data.”

The court also found the expert’s Monte Carlo simulation attempts to be misleading as the minimum range used for determining the number of hours the worker may have had gasoline on his hands in any given day was 1.25 hours, despite testimony from fact witnesses stating that the worker had gasoline on his hands “most days, not on all days”:  “Given that a Monte Carlo simulation attempts to gauge all possibilities within a range of all potential periods of exposure, [the expert] inexplicably failed to account for zero hours as the minimum of the range.”

The court was also struck by the expert’s decision to account for evaporation for some calculations but ignore evaporation when doing so was harmful to his resulting calculations.

For a look at a recent article published by Sutherland partners Matt Gatewood and Susan Lafferty in FUEL Magazine regarding the predicted next wave of benzene-exposure cases, click here.



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