This is a toxic tort case wherein Plaintiff’s experts were excluded under Daubert principles and Defendant’s summary judgment motions for general and specific causation were granted.  The opinion by Hon. Justin Quackenbush (Senior Judge) is an extremely thorough and scholarly analysis that contributes significantly to the body of Daubert case law.

The plaintiff, a tanker truck driver, sued ConocoPhillips and others, claiming that his occupational exposure to gasoline caused a form of cancer, acute myelogenous leukemia (AML).  While the medical and scientific evidence supports the proposition that AML can be caused by exposure to the chemical benzene, the science is more equivocal when it comes to gasoline, which contains benzene as a minor component.  Defendant attacked the scientific methodology employed by plaintiffs’ experts, arguing that the case was a gasoline and not a benzene case, despite the presence of benzene in gasoline.

This case represents a significant victory for the gasoline refining and marketing industry, involving its number one product.  An adverse result would have sent shock waves, and potentially opened the door to a new mass tort wave.  The potential number of persons exposed to gasoline vapors in the workplace and at the pump is huge.  Discouraging those who would seek to connect such exposure to cancer is of major importance to the industry.


Plaintiff Neil Henricksen was employed as a tanker truck driver.  His job duties required him to load and unload cargo (typically gasoline and diesel fuel) several times per day over a period of many years.  Defendant operated a petroleum product terminal in Spokane, Washington where Plaintiff loaded his truck.  Plaintiff’s alleged exposure to benzene in gasoline was the basis for his lawsuit against Defendant.  Plaintiff alleged that his acute myelogenous leukemia (AML) was caused by exposure to benzene while loading gasoline at Defendant’s terminal.

Daubert Challenges

To support his case, Plaintiff designated experts from the fields of industrial hygiene, warnings, hematology, epidemiology, and toxicology.  Plaintiff’s causation experts included hematologists (John Caton, Frank Gardner), a toxicologist (William Sawyer), and an epidemiologist (Peter Infante).  Plaintiff’s dose calculation experts included a professional engineer (Marco Kaltofen) and a toxicologist (William Sawyer).  Defendant successfully challenged the methodologies of Plaintiff’s expert witnesses and all five were excluded by the Court.  Henricksen v. ConocoPhillips Co., 605 F.Supp2d 1142 (E.D. Wash., February 11, 2009).

Frank Gardner, MD

The causation opinion of Plaintiff’s expert in hematology (“Gardner”) was excluded for three methodological reasons.  First, Gardner’s general causation opinion (gasoline exposure causes AML) was excluded because he could not “point to any source which reliably supports his conclusion.”  Id. at 1161.  As the Court noted, this methodological flaw “renders his opinion merely [a] personal opinion.”  Id.

Second, Gardner’s specific causation opinion was excluded because he neither attempted to calculate his own dose assessment for Plaintiff nor relied on the dose assessment of any other expert.  Id. at 1162.  In short, while agreeing that benzene-induced AML is a dose-dependent phenomenon, Gardner opined on specific causation without a dose.  Id.  As the Court explained, “this renders his opinion on specific causation inherently unreliable.”  Id.

Finally, Gardner’s specific causation opinion was excluded because he did not “reliably rule out reasonable alternative causes of [the alleged harm] or idiopathic causes.”  Id. (citing Soldo v. Sandoz Pharmaceuticals Corp., 244 F.Supp.2d 434, 567 (W.D. Pa. 2003)).  As the Court made clear, “the presence of a known risk factor is not a sufficient basis for ruling out idiopathic origin in a particular case, particularly where most cases of the disease have no known cause.”  Id.  The Court paid careful attention to the presentation of Plaintiff’s disease and described ways in which Plaintiff’s presentation could have been compared to individuals with and without benzene-induced AML.  Id. at 1162-63.  Garder performed no such analysis.

John Caton, MD

John Caton, one of Plaintiff’s treating physicians, opined that Plaintiff’s occupational exposure to gasoline caused his AML.  Although the Court struck Caton on procedural grounds, it noted that Caton’s opinions would have not have withstood Daubert scrutiny.  Id. at 1160.  Caton’s main methodological flaw was that he failed to consult the relevant literature before offering an opinion on causation.  Id.

William Sawyer, PhD

Dr. William Sawyer provided both causation opinions and a retrospective dose calculation for Plaintiff.  Neither opinion survived Daubert scrutiny because, as the Court noted, “At each step of his analysis, Sawyer bases his analysis upon speculation and/or erroneous data, and without adequate explanation, these steps render his methodology unreliable and misleading, and his opinions are therefore inadmissible.”  Id. at 1163.

Dr. Saywer’s causation opinion was rejected for one principal reason: he embraced the “no safe level” model for carcinogenicity.  Citing to numerous district court and appellate court opinions, as well as to the Federal Judicial Center Reference Manual on Scientific Evidence (2d ed. 2000), the Court recognized that the “no safe level” theory is: (1) a hypothesis that cannot be tested, verified, or falsified, (2) has been rejected by a majority of the scientific community, and (3) has no known potential rate of error.  Id. at 1166.  About Sawyer’s theory, the Court wrote:

“Sawyer's theory that any amount of exposure more than negligible should be considered substantial risk factor for AML flies in the face of the scientific literature reviewed and other expert testimony in this case that there is a threshold or dose below which you do not see a statistically significant risk of developing AML. Even though benzene has been shown to cause AML, it is too difficult a leap to allow testimony that says any amount of exposure (above the short term exposure limits) to this toxin can cause AML and caused AML in Henricksen.

Because Sawyer's dose calculation is unreliable and his belief that low-dose exposure to benzene as a component of gasoline is capable of causing AML a hypothesis rather than science sufficiently reliable for causation purposes, it is fails the Daubert factors.”

Id. at 1166.

Sawyer’s dose calculation did not survive for three reasons: (1) he cherry-picked a non-representative study from which to base his overall calculation, (2) he cherry-picked an exposure value (and the less reliable value) from within that study, and (3) his calculation was full of factual errors.  Id. at 1164-65.

If Dr. Sawyer had relied on published industrial hygiene data describing the exposure of U.S. tanker-truck drivers (like Plaintiff), the remainder of his errors may have gone unreported.  Instead, Sawyer relied on a small and obscure Japanese study with an unknown work environment, and without explaining the scientific reason for doing so.  Id. at 1164.  As the Court noted: “While Rule 702 does not require an expert to find a study linking the exact facts, it does require the expert [to] demonstrate a scientifically valid basis for projecting the findings of a study to the proffered casual theory. Sawyer has not provided an adequate basis for reliably linking the values derived from the circumstances of [the Japanese study] to the circumstances of Henricksen's case.”  Id. at 1164-65

Marco Kaltofen, PE

Marco Kaltofen also attempted to perform a retrospective benzene dose calculation.  Had Mr. Kaltofen relied on the reported data describing exposure among U.S. tanker truck drivers, his methodology may have survived.  Instead, Kaltofen relied on a Swedish study, made an assumption from that study which the authors never reported, and then applied his assumption to Plaintiff’s work environment without any support in the literature for doing so.  Id. at 1167.  The Court noted that Kaltofen’s assumption (“the five times multiplier”) had never been tested, recognized by an expert in the field, or reported in the literature.  Id.  Other factors weighing against admissibility were that Kaltofen’s methodology was crafted for purposes of rendering an opinion in this case, and that it was subject to a wide rate of error.  Id. at 1168.  The Court concluded:

“Kaltofen's methodology in arriving at the multiplier of 5 shows a lack of scientific rigor in that he expands the application of [the Swedish study] beyond good science, drawing conclusions the authors of the study did not make from limited data. It is this kind of scientifically unsupported “leap of faith” which is condemned by Daubert.”

Id. at 1168.

Peter Infante, PhD

Dr. Infante’s general causation opinion (gasoline exposure causes AML in humans) and specific causation opinion (low-dose benzene exposure from gasoline caused Plaintiff’s AML) were excluded because the studies advanced for those propositions did not support them.  In both instances the Court noted that there was simply “too great an analytical gap between the data and the opinion proferred.”  Id. at 1168, 1170.  Infante’s specific causation opinion was also struck because he relied on Marco Kaltofen’s unreliable dose assessment.  Id. at 1176.

Summary Judgment

Defendant moved for summary judgment on the grounds of general causation and specific causation.  Having excluded Plaintiff’s causation experts because the literature they relied upon did not support their opinions, Plaintiff could not meet his summary judgment burden:

None of the studies relied upon have concluded that gasoline has the same toxic effect as benzene, and none have concluded that the benzene component of gasoline is capable of causing AML. The studies relied upon by Plaintiffs make clear that the connection between gasoline or the benzene component of gasoline and AML is at this point in time only a hypothesis in need of further investigation. Based upon the court's review of these studies Plaintiffs' experts can only reliably attest to gasoline exposure as a theoretical or possible cause, not a probable cause of Henricksen's AML

Id. at 1176.

Without reliable evidence of general causation, Plaintiffs' experts can not analyze specific causation while comporting with the scientific method. However, even if the court were to admit the testimony that gasoline is generally capable of causing AML, these studies do not support the conclusion that exposure at 8 ppm-years is capable of causing AML.

Id. at 1176.


Henricksen v. ConocoPhillips Co. is an important opinion for two reasons.  First, it is a landmark opinion concerning the non-carcinogenicity of gasoline.  The scientific “evidence” put forward by Plaintiff to support his claim, and the experts hired to advocate for Plaintiff’s position, were scientifically and legally inadequate to survive a summary judgment challenge.  Second, the opinion provides practitioners with thorough and well-reasoned application of Daubert principles to a variety of expert methodologies.

July 2009

Brett J. Young
Senior Associate
Fulbright & Jaworski L.L.P.
1301 McKinney Suite 5100
Houston, Texas 77010-3095
(713) 651-5200 direct
(713) 651-5246 facsimile

Bookmark and Share

Categories: Daubert | Expert Witnessess | Toxic Tort

Actions: E-mail | Comments


Submit Blog

If you wish to submit a blog posting for DRI Today, send an email to with "Blog Post" in the subject line. Please include article title and any tags you would like to use for the post.

Search Blog

Recent Posts




Staff Login