This Court is satisfied that in the instant case plaintiff's experts have employed scientifically valid methodologies and that their causation opinions qualify as scientific knowledge. In arguing to the contrary, defendant confuses, at times ignores, the crucial distinction between the admissibility of expert scientific testimony and the weight such testimony should be afforded by the trier of fact.
Dr. Swerdlow is a hematologist who first treated plaintiff in 1989 and later diagnosed her MDS 5 q-minus. Dr. Thomas James Callender is a clinical physician and researcher who specializes in occupational and environmental toxicology. Plaintiff consulted him in 1993. He has treated hundreds of patients exposed to benzene. Dr. Charles E. Hess is a clinical and research physician at the University of Virginia Medical Center who specializes in hematologic malignancies, including leukemia and myelodysplastic syndromes. He has been treating the plaintiff since May of 1995. Dr. Hess has treated hundreds of patients with MDS and related disorders.
All three medical doctors employed a "differential diagnosis" methodology in reaching their opinion that the plaintiff's MDS 5 q-minus was caused by her exposure to benzene from Orafix Special. This methodology involves first identifying possible causes of a patient's symptoms and then differentiating among them. Thereafter other possible causes are sought to be ruled out, usually through further examination and laboratory tests. Drs. Swerdlow and Hess stated that their causation opinions were based an examination of the plaintiff's medical history, the lack of other causative agents such as direct exposure to radiation or pesticides, and a review of medical literature connecting exposure to benzene to bone marrow disorders like MDS and leukemia.
The reliability of this methodology is well established. In a similar case, the Fourth Circuit recently affirmed the admission of expert testimony based on this methodology. Benedi v. McNeil-P.P.C. Inc., 66 F.3d 1378, 1384 (4th Cir. 1995). In Benedi, the plaintiff alleged that use of Tylenol in combination with regular alcohol consumption caused his severe liver damage. He sued the manufacturer under negligent failure to warn and implied warranty theories. The Fourth Circuit affirmed the district court's admission of the testimony of treating physicians who based their causation opinions on the appearance of the plaintiff's liver, the amount of Tylenol found in his blood, his medical history and regular use of alcohol, review of medical literature, and the absence of any other apparent cause of plaintiff's liver failure., Id. "In light of the medical community's daily use of the same methodologies in diagnosing patients," the Fourth Circuit refused to find that this methodology was unreliable or unsound. Id.
Dr. Swerdlow is a specialist in hematology, Dr. Callender has treated hundreds of patients exposed to benzene, and Dr. Hess has treated numerous patients with MDS.
Before litigation commenced all three were familiar with the medical literature which establishes a strong correlation between benzene exposure and the occurrence of bone marrow disorders such as aplastic anemia, acute leukemia, and MDS. In fact, all the experts in this case, including defendant's, have acknowledged that it is accepted in the medical community that in sufficient doses benzene is a bone marrow toxin.
Although somewhat disputed, there is also evidence that the mechanisms of development for MDS and leukemia are very similar, if not identical. It is not clear exactly how benzene causes leukemia or MDS. However it is known that benzene is metabolized in the liver and the metabolites are distributed throughout the body. Other substances in the body absorb these metabolites and can destroy genetic material in the bone marrow. With MDS, this damage results in abnormal production and maturation of red and white blood cells but not a complete destruction of bone marrow as in leukemia. Dr. Swerdlow stated that since the types of biochemical lesions which cause leukemia are very similar to the lesions which cause MDS he would expect that what causes one lesion would cause the other. Drs. Swerdlow and Hess also claimed that a significant percentage (10-30%) of leukemia patients undergo a myelodysplastic syndrome before they progress to leukemia. Dr. Swerdlow predicted that this transformation would be even more prevalent in benzene-induced leukemia because the myelodysplastic syndrome stage has passed unnoticed by the time the leukemia is diagnosed.
The plaintiff's causation theory, then, is a far cry from the theories advanced by plaintiffs in the Benedictin cases where an "overwhelming" body of evidence contradicted the experts' conclusions. See Raynor v. Merrell Pharmaceuticals Inc., 104 F.3d 1371, 1997 WL 18170, at *5 (D.C. Cir. 1997); Richardson v. Richardson-Merrell, Inc., 273 U.S. App. D.C. 32, 857 F.2d 823 (D.C. Cir. 1988), cert. denied, 493 U.S. 882, 107 L. Ed. 2d 171, 110 S. Ct. 218 (1989). In the instant case, the weight of scientific evidence connecting benzene and MDS supports rather than contradicts the doctors' opinions that benzene causes MDS 5 q-minus.
To avoid this result, defendant returns to the same argument again and again -- that there is no established evidence demonstrating a causative link between benzene exposure and MDS 5 q-minus. The absence of epidemiological studies, however, while important, is not dispositive as long as the methodology employed by the expert is sound. Benedi, 66 F.3d at 1384; Ferebee v. Chevron Chemical Co., 237 U.S. App. D.C. 164, 736 F.2d 1529, 1536 (D.C. Cir.)("a cause-effect relationship need not be clearly established by animal or epidemiological studies before a doctor can testify that . . . such a relationship exists"), cert. denied, 469 U.S. 1062, 83 L. Ed. 2d 432, 105 S. Ct. 545 (1984).
This is especially true when the disease is an extremely rare disorder like MDS 5 q-minus. For one, MDS 5 q-minus has not been included in any of the epidemiological studies on benzene exposure. Furthermore, MDS and MDS 5-q minus have only recently been identified as separate medical conditions.
Plaintiff's experts did consider, however, published case reports and prospective studies which found a statistically relevant correlation between benzene exposure and MDS.
Defendant also argues that these opinions are inadmissible because the doctors have not published their views in peer reviewed journals. The Supreme Court in Daubert declared the fact of peer review and publication a "pertinent" factor in the gatekeeping inquiry. 509 U.S. at 593. The Supreme Court wrote that "submission to the scrutiny of the scientific community is a component of good science" but recognized that "some propositions . . . are too particular, too new, or of too limited interest to be published." Id. See also Daubert v. Merrell Dow Pharmaceuticals, Inc., 43 F.3d 1311, 1318 n.9 (9th Cir.), cert. denied, 133 L. Ed. 2d 126, 116 S. Ct. 189 (1995). Again MDS 5 q-minus is a rare and relatively newly discovered condition and it is not surprising -- nor probative of its scientific validity -- that the experts' theories have not been published. Moreover the experts' findings flow directly from research connecting benzene and MDS -- research which has been exhaustively published and peer reviewed. It is not dispositive, then, that these scientific opinions have not been published.
Nor is it particularly significant that the doctors could not affirmatively eliminate spontaneous chromosomal mutation as a cause of plaintiff's MDS 5 q-minus. The differential diagnosis methodology, based on the scientific method, requires that alternate causes of the condition be eliminated. However, an expert must not eliminate each and every possible alternative cause. This is especially true when a plaintiff can establish general causation, or a definitive "link" between the causative agent and the condition it allegedly produced. Raynor v. Merrell Pharmaceuticals Inc., 104 F.3d 1371, 1997 WL 18170, at *5. This burden would be particularly onerous in this case given that spontaneous chromosomal mutation is a difficult phenomenon for scientists to understand. "The fact that several possible causes might remain 'uneliminated' . . . only goes to the accuracy of the conclusion, not the soundness of the methodology." Ambrosini, 101 F.3d at 140 (citing Mendes-Silva v. United States, 299 U.S. App. D.C. 39, 980 F.2d 1482, 1487 (D.C. Cir. 1993)). This plaintiff has established that there is a clear link between benzene contamination and MDS. As a result, it is not fatal to the admissibility of plaintiff's experts' testimony regarding specific causation that her experts cannot eliminate every possible cause of her condition.
Defendant also takes issue with the scientific opinion of Dr. Paul S. Blanke, the "dosage" expert. Dr. Blanke is the former Director of the Toxicology Laboratory of the Medical College of Virginia Hospitals and Professor of Pathology, Pharmacology and Toxicology in the Schools of Medicine and Basic Sciences of Virginia Commonwealth University. He calculated that the dosage of benzene which plaintiff absorbed over the six year period was between 550 to 4200 mg. He also determined that this level of exposure was sufficient to cause plaintiff's disease. All three of plaintiff's experts relied on these results in diagnosing benzene as the cause of plaintiff's MDS 5 q-minus.
Plaintiff provided Dr. Blanke with two tubes of Orafix Special, which he sent for laboratory tests conducted by Dr. Joseph Saady. Lab results indicated that one tube of Orafix Special contained 110 parts per million ("ppm") of benzene and the other contained 230 ppm. Dr. Blanke had to revise his first set of calculations when he discovered that he had used the wrong tube sizes. In his revised calculations, Dr. Blanke assumed that plaintiff applied the entire contents of a 2.4 ounce tube of Orafix Special twice a day for a period of 25 days. Based on her claims that she applied the denture adhesive twice a day 90% of the time, he estimated the days of use from January of 1985 until four different stopping points. He then estimated the grams of benzene plaintiff was exposed to during each of the four time periods and how much benzene plaintiff would have absorbed, assuming gradually increasing levels of benzene in the product. He assumed eight different benzene values (in parts per million): 162, 200, 300, 350, 450, 600, and 750.
Dr. Blanke followed the reasoning and methodology required of a toxicologist. The Federal Judicial Center has outlined the role of a toxicologist in clinical poisoning cases:
First, the toxicologist should analyze whether the disease can be related to chemical exposure by a biologically plausible theory. Second, the expert should examine if the plaintiff was exposed to the chemical in a manner that can lead to absorption in the body. Finally, the expert should offer an opinion as to whether the dose to which the plaintiff was exposed is sufficient to cause the disease.