Full opinion text
OPINION AND ORDÉR ROBERT E. JONES, District Judge: 1. INTRODUCTION Currently pending in this court are a number of silicone breast implant cases brought by or on behalf of the plaintiffs against various breast implant manufacturers. Plaintiffs seek damages for injuries they claim to have suffered as a result of implantation with silicone gel breast implants. Among other things, the plaintiffs assert that silicone from the implants has migrated and degraded in their bodies and has caused a systemic syndrome or illness, which they generally refer to as “atypical connective tissue disease” (ACTD). In essence, plaintiffs claim a “unique constellation of symptoms” consisting of hundreds of symptoms commonly experienced by the general population. This opinion addresses the defendants’ motions in limine to exclude testimony by plaintiffs’ experts concerning any causal link between silicone breast implants and the alleged systemic disease - or syndrome. To resolve these motions, the court, in its role as “gatekeeper” (see Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 113 S.Ct. 2786, 125 L.Ed.2d 469 (1993) (hereinafter Daubert I), initiated proceedings under Federal Rule of Evidence 104. The process through which the court has endeavored to ■ resolve the pending motions, a process the court believes to be unique in federal practice to date, is described below. II. FACTS AND PROCEDURAL BACKGROUND The breast implant cases at issue here were either filed initially in this court or removed from state court. The cases were then transferred to the Judicial Panel for Multidistrict Litigation, In re Silicone Gel Breast Implant Products Liability Litigation, MDL No. 926, 1994 WL 114580, where they have been managed expeditiously under the watchful eye of the transferee judge, Chief Judge Sam C. Pointer, Jr. In 1995 and 1996, Judge Pointer remanded a number of cases to Oregon for trial. All breast implant cases remanded to Oregon, federal district court have been assigned to this judge. After a series of status conferences involving all interested parties and counsel, I determined that, at least initially, similar cases should grouped for trial. I designated the following three trial groups: Plaintiffs Defendants) Group 1 Hall Pope Stern Preskey Baxter Group 2. Andrews , Johnston Eisele Bentley Tytlar Bristol-Myers Squib Group 3 Shervey Zingarelli Adamson D. Hall Young Mitchel Bristol-Myers and Medical Engineering Corp. After initial trial dates were set, the court instructed counsel for Groups 1 and 2 to provide a list of all lay and expert witnesses to be called at trial, together with a narrative statement of each witness’ proposed testimony. The court also instructed counsel to summarize each expert witness’ opinion, to identify all the materials upon which each expert would rely for his or her opinions, and to submit transcripts of any testimony given by the witness in similar cases. Once the witness materials were duly filed, in July 1996, defendants jointly filed a series of motions in limine to exclude plaintiffs’ experts’ testimony concerning causation. To address these motions, I scheduled an integrated hearing under Rule 104(a) on the admissibility of the scientific evidence. All interested parties and counsel were invited to attend the hearing, which I set for August 1996. In view of the complicated scientific and medical issues involved and in an effort to effectively discharge my role as “gatekeeper” under Daubert I, I invoked my inherent authority as a federal district court judge to appoint independent advisors to the court. See, e.g., Goetz v. Crosson, 967 F.2d 29, 37 (2d Cir.1992) (VanGraafeiland, J., concurring and dissenting) (citing Scott v. Sponger Bros., Inc., 298 F.2d 928 (2d Cir.1962)); see also 1972 Advisory Committee Notes to FRE 702. Pursuant to that inherent authority, I began a search to find technical advisors with the necessary expertise in the fields of epidemiology, immunology/toxicology, rheumatology, and chemistry to assist in evaluating the reliability and relevance of the scientific evidence. Dr. Richard Jones, M.D., Ph.D., assisted the court by screening dozens of potential appointees and ultimately selecting four totally unbiased and uncommitted experts in the necessary fields, which the court approved and appointed. The technical ad-, visors and their fields of expertise are: Mer-wyn R. Greenlick, Ph.D. (epidemiology); Robert F. Wilkens, M.D. (rheumatology); Mary Stenzel-Poore, Ph.D. (immunology/toxicology); and Ronald McClard, Ph.D. (polymer chemistry). . With the exception of Dr. McClard, whom I appointed shortly after the initial Rule 104 hearing terminated, the technical advisors reviewed the parties’ voluminous materials in preparation for the hearing and observed most of the testimony in court. After his appointment, Dr. McClard reviewed all of the relevant materials and the videotaped arguments of counsel, and participated in all subsequent proceedings. I structured the Rule 104 hearing according to subject matter, with plaintiffs presen^ • ing their experts in a particular field, followed by defendants’ witnesses in the same field. All participating parties stipulated to the experts’ qualifications under Rule 702. Because in proceedings pursuant to Rule 104(a) the court is not bound by rules of evidence, except those that pertain to privileges I ruled that no evidentiary objections would be permitted. At the hearing, which spanned four intense days (August 6-8, 1996), experts on both sides were questioned by counsel, the court, and the technical advisors. The parties then submitted videotaped summations, which the court and all technical advisors reviewed. The court also asked the parties to submit proposed questions to guide the technical advisors in evaluating the testimony and preparing their reports. After considering the parties’ proposed questions, the court prepared and submitted the following questions to the advisors: 1. Is the expert’s opinion supported by scientific reasoning and methodology that is generally accepted in the expert’s particular scientific community or otherwise qualified as stated in Daubert II, as quoted above? 2. Is the expert’s opinion based upon scientifically reliable data? 3. If epidemiological studies have not been done or are inconclusive, what other data, such as animal studies, biophysical data, clinical experience in the field, medical records, differential diagnosis, preliminary studies, general scientific knowledge, and medical literature can justify, to a reasonable medical probability, a conclusion concerning the cause of the syndrome or disease at issue? 4. Do the methodology and data support the expert’s conclusions? 5. Does the scientific data relied upon by the expert apply to the syndrome or disease in issue in these cases? For instance, are epidemiological studies directed at other typical or classical diseases relevant to an atypical disease? The court also submitted almost all of the parties’ proposed questions to the technical advisors for their consideration, with this instruction: We are also enclosing suggested questions and references provided by counsel. Do not feel obligated to answer all of counsel’s questions, but respond to those that you feel are relevant and that you feel will be helpful to the court in discharging our “gatekeeping” role. For instance, the defense contends that the record of the hearing does not reflect the plaintiffs’ reconstruction of their witness’ testimony. We leave that issue to you. The technical advisors submitted their reports to the court in September 1996, and on September 13, 1996, the court gave counsel on both sides an opportunity to question them. Following this hearing, the court expressed preliminary concerns that plaintiffs’ position could not be sustained and asked defense counsel to submit proposed findings of fact and conclusions of law. Plaintiffs then filed objections and proposed alternative findings, and the defendants filed a further response. Having fully reviewed the entire record and the reports of the advisors, I am now prepared to rule on the pending rule 104 hearing motions in limine. For the reasons explained below, the defendants” motions in limine to exclude plaintiffs’ expert testimony concerning causation of any systemic disease or syndrome are GRANTED. I note, however, that while this court was in the midst of the Rule 104 proceedings, Judge Pointer appointed a national panel of experts pursuant to FRE 706 to assist in a similar evaluation of the scientific evidence in the MDL. As recognized by Senior Judge Jack B. Weinstein and Judge Harold Baer, Jr., in their recent joint opinion in breast implant cases pending in the Southern and Eastern Districts of New York (see In re Breast Implant Cases (Amended Preliminary Memorandum Oct. 23,1996)), it will probably be some time before the national panel completes its important work. In view of the ongoing national proceedings and the potential for further scientific developments during their pendency, the court will defer the effective date of this opinion until the findings of the national Rule 706 panel are available. Depending on the court’s evaluation of those findings, plaintiffs in these cases may seek reconsideration, if appropriate, of this decision. Plaintiffs’ motion to add the national Rule 706 panel members to the witness lists in Groups 2 and 3 is also deferred pending completion of the panel’s work. III. ADMISSIBILITY STANDARDS A. Rule 702 and Rule 104(a) The Federal Rules of Evidence govern in diversity cases, except in the rare circumstance where a state rule of evidence is “ ‘intimately bound up’ with the rights and obligations being asserted * * Wray v. Gregory, 61 F.3d 1414, 1417 (9th Cir.1995) (quoting Erie R.R. Co. v. Tompkins, 304 U.S. 64, 78, 58 S.Ct. 817, 822, 82 L.Ed. 1188 (1938)). With respect to the issues presently before the court, no state evidence rule supplants the federal rules. Rule 702 is the starting point for any evaluation of the admissibility of expert testimony. Daubert I, 509 U.S. at 589, 113 S.Ct. at 2794-95 (Rule 702 is the “primary locus” of the expert screening “obligation”). Rule 702 provides: If the scientific, technical or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise. The assessment of whether proffered expert testimony is admissible under Rule 702 is a preliminary question for the court under Rule 104(a). Daubert I, 509 U.S. at 592, 113 S.Ct. at 2796. Rule 104(a), which provided the framework for the hearing in this case, states: Preliminary questions concerning the qualification of a person to be a witness, the existence of a privilege, or the admissibility of evidence shall be determined by the court, subject to the provisions of subdivision (b). In making its determination it is not bound by the rules of evidence except those with respect to privileges. The Ninth Circuit recently emphasized that the proponent of the expert testimony bears the burden of proving admissibility under Rule 104. Lust v. Merrell Dow Pharmaceuticals, Inc., 89 F.3d 594, 598 (9th Cir.1996) (“[i]t is the proponent of the expert who has the burden of proving admissibility”); see also Daubert v. Merrell Dow Pharmaceuticals, Inc., 43 F.3d 1311, 1316 (9th Cir.1995) (hereinafter Daubert II) (“the party presenting the expert must show that the expert’s findings are based on sound science”). In this case, the plaintiffs, as proponents of the evidence, have the burden of establishing admissibility by a preponderance of the evidence. Daubert I, 509 U.S. at 592 n. 10, 113 S.Ct. at 2796 n. 10. In determining whether the plaintiffs have met their burden of establishing the admissibility of their expert evidence, the court is guided by Rule 702 and the recent Supreme Court and Ninth Circuit decisions interpreting it, particularly Daubert I and Daubert II. In Daubert I, the Supreme Court clarified that adoption of Rule 702 displaced the traditional Frye test, which made “general acceptance” in the relevant scientific community the prerequisite to admissibility. Daubert I, 509 U.S. at 589, 113 S.Ct. at 2794-95. Instead, under Daubert I, which. focused closely on the language of Rule 702, expert scientific opinion is admissible if it qualifies as “scientific knowledge” and is therefore sufficiently “reliable.” Daubert I, 509 U.S. at 589-90, 113 S.Ct. at 2795; see also Lust, 89 F.3d at 597. According to Daubert I, “the adjective ‘scientific’ implies a grounding in the methods and procedures of science,” and “the word ‘knowledge’ connotes more than subjective belief or unsupported speculation.” 509 U.S. at 590, 113 S.Ct. at 2795. The Court explained that in order to qualify as “scientific knowledge,” an inference or assertion must be derived by the scientific method. Proposed testimony must be supported by appropriate validation — i.e., “good grounds,” based on what is known. Id. The requirement that an expért’s testimony pertain to “scientific knowledge” “es^ tablishes a standard of evidentiary reliability,” i.e., trustworthiness. 509 U.S. at 590 and n. 9, 113 S.Ct. at 2795 and n. 9. The Supreme Court charged district courts with the duty to act as “gatekeepers,” to ensure that any and all scientific testimony or evidence admitted is not only relevant, but reliable. Daubert I, 509 U.S. at 597-98, 113 S.Ct. at 2798-99. Thus, the court must determine at the outset, pursuant to Rule 104(a), “whether the expert is proposing to testify to (1) scientific knowledge that (2) will assist the trier of fact to understand or determine a fact in issue.” Id. at 592-93, 113 S.Ct. at 2796. This determination “entails a preliminary assessment of whether the reasoning or methodology underlying the testimony is scientifically valid and of whether that reasoning or methodology properly can be applied to the facts in issue.” Id. The task before this court, then, is two-pronged. First, the court must determine whether plaintiffs’ experts’ testimony reflects “scientific knowledge,” constitutes “good science,” and was “derived by the scientific method.” Daubert II, 43 F.3d at 1316. Second, the court must ensure that the proposed testimony “fits,” that is, that the testimony is “‘relevant to the task at hand’ ” in that it “logically advances a material aspect of the proposing party’s ease.” Id. at 1315 (quoting Daubert I, 509 U.S. at 597, 113 S.Ct. at 2798-99). 1.Reliability. Daubert I and Daubert II list several factors to guide federal courts in deciding the first prong, whether the expert testimony is scientifically valid and therefore reliable. These factors, which may or may not apply in a particular case, include: 1. Whether the theory or technique employed by the expert, is generally accepted in the scientific community; 2. Whether the theory has been subjected to peer review and publication; 3. Whether the theory can be and has been tested; 4. Whether the known or potential rate of error is acceptable; and 5. Whether the experts are. proposing to testify about matters growing naturally or directly out of research, or whether they have developed their opinions expressly for purposes of testifying. Daubert I, 509 U.S. at 593-94, 113 S.Ct. at 2796-97 (first four factors); Daubert II, 43 F.3d at 1316-17 (adding fifth factor). The list is illustrative, not exhaustive. Daubert II, 43 F.3d at 1317. As mentioned earlier, with respect to the first listed factor, whether the expert’s theory or method is generally accepted, the Ninth Circuit explained in Daubert II that in certain circumstances it may be sufficient if a minority in the scientific community accepts the methods employed, but only if the proponent demonstrates in “some objectively verifiable way that the expert has both chosen a reliable scientific method and followed it faithfully.” Daubert II, 43 F.3d at 1319 n. 11. 2. Fit. Even if the proponents meet their burden of establishing that an expert’s testimony qualifies as scientific knowledge, the court must still exclude the evidence if it does not “fit” the matters at issue in the case. Daubert I, 509 U.S. at 591, 113 S.Ct. at 2795-96. As the Ninth Circuit in Daubert II, explained, to “fit,” testimony must “logically advance a material aspect of the proposing party’s case.” Daubert II, 43 F.3d at 1315; see also In re Paoli R.R. Yard PCB Litigation, 35 F.3d 717, 743 (3d Cir.1994) (hereinafter Paoli II). In Paoli II, Judge Becker described the “fit” requirement as follows: For example, animal studies may be methodologically acceptable to show that chemical X increases the risk of cancer in animals, but they may not be methodologically acceptable to show that chemical X increases the risk of cancer in humans. Daubert explains that, “‘[f]it’ is not always obvious, and scientific validity for one purpose is not necessarily scientific validity for other, unrelated purposes.” * * * Thus, even if an expert’s proposed testimony constitutes scientific knowledge, his or her testimony will be excluded if It is not scientific knowledge for purposes of the case. “Rule 702’s ‘helpfulness’ standard requires a valid scientific connection to the pertinent inquiry as a precondition to admissibility.” * * * For example, in order for animal studies to be admissible to prove causation in humans, there must be good grounds to. extrapolate from animals to humans, just-as the methodology of the studies must constitute good grounds to reach conclusions about the animals themselves. Thus, the requirement of reliability, or “good grounds,” extends to each step in an expert’s analysis all the way through the step that connects the work of the expert to the particular case. Paoli II, 35 F.3d at 743 (citations omitted; emphasis in original). As the defendants correctly point out in their proposed findings and conclusions, the issue before the court, as in the Bendectin litigation considered in Daubert II, is causation. In Daubert II, the Ninth Circuit concluded that the plaintiffs in that case failed to make any objective showing of admissibility under the first prong of Rule 702. Because the plaintiffs had submitted their expert materials while Frye was the law of the circuit, however, rather than remand the case to permit the plaintiffs to augment the record, the court proceeded to reach the second prong, or “fit” requirement, of the Daubert I analysis. Daubert II, 43 F.3d at 1320. In doing so, the court explained that in assessing whether proffered expert testimony “will assist the trier of fact” in resolving the causation issue, the court must look to the substantive standard — in that case, California tort law. The court commented: California tort law requires plaintiffs to show not merely that Bendectin increased the likelihood of injury, but that it more likely than not caused their injuries. * * * In terms of statistical proof, this means that plaintiffs must establish not just that their mothers’ ingestion of Ben-dectin increased somewhat the likelihood of birth defects, but that it more than doubled it—only then can it be said that Bendectin is more likely than not the source of their injury. Because the background rate of limb reduction defects is one per thousand births, plaintiffs must show that among children of mothers who took Bendectin the incidence of such defects was more than two per thousand. Id. at 1320 (citation omitted). The substantive standard under Oregon tort law is quite similar to the California standard. Under Oregon law, the plaintiffs in this litigation must prove not merely the possibility of a causal connection between breast implants and the alleged systemic disease, but the medical probability of a causal connection. See Harris v. Kissling, 80 Or. App. 5, 9, 721 P.2d 838 (1986); see also Griffin v. K.E. McKay’s Market of Coos Bay, Inc., 125 Or .App. 448, 451-52, 865 P.2d 1320 (1993), in which the court stated: [The plaintiff] must introduce evidence which affords a reasonable basis for the conclusion that it is more likely than not that the conduct of the defendant was a substantial factor in the result. A mere possibility of such causation is not enough * * * (Citation omitted.) Under this substantive standard, if an expert cannot state the causal connection in terms of probability or certainty, the expert’s testimony must be excluded under the second prong of Rule 702. In Daubert II, for example, the Ninth Circuit affirmed the district court’s exclusion of certain of plaintiffs’ experts’ opinions, reasoning that: As the district court properly found below, “the strongest inference to be drawn for plaintiffs based on the epidemiological evidence is that Bendectin could possibly have caused plaintiffs’ injuries.” * * * The same is true of the other testimony derived from animal studies and chemical structure analyses—these experts “testify to a possibility rather than a probability.” * * * Unlike these experts’ explanation of their methodology, this is not a shortcoming that could be corrected on remand; plaintiffs’ experts could augment their affidavits with independent proof that their methods were sound, but to augment the substantive testimony as to causation would require the experts to change their conclusions altogether. Any such tailoring of the experts’ conclusions would, at this stage of the proceedings, fatally undermine any attempt to show that these findings were ‘derived by the scientific method.’ Plaintiffs’ experts must, therefore, stand by the conclusions they originally proffered, rendering their testimony inadmissible under the second prong of Fed. R.Evid. 702. Daubert II, 43 F.3d at 1322 (citation omitted; emphasis added). 3. Methodology v. Conclusions. The plaintiffs insist that this court must focus solely on the expert’s methodology and may not consider the experts’ conclusions in any respect. Certain language in Daubert I can be read, superficially, to support plaintiffs’ position. The Daubert I Court wrote: The inquiry envisioned by Rule 702 is, we emphasize, a flexible one. Its overarching subject is the scientific validity — and thus the evidentiary relevance and reliability— of the principles that underlie a proposed submission. The focus, of course, must be solely on principles and methodology, not on the conclusions that they generate. Daubert I, 509 U.S. at 595, 113 S.Ct. at 2797 (emphasis added). Since Daubert I was decided, however, courts and commentators have wrestled with the methodology/eonclusion distinction, concluding that the distinction is of limited practical import. In Paoli II, for example, Judge Becker offered the following cogent analysis: Plaintiffs are correct, of course, that Dau-bert requires the judge’s admissibility decision to focus not on the expert’s conclusions but on his or her principles and methodology. * * * But we think that this distinction has only limited practical import. When a judge disagrees with the conclusions of an expert, it will generally be because he or she thinks that there is a mistake at some step in the investigative or reasoning process of that expert. If the judge thinks that the conclusions of some other expert are correct, it will likely be because the judge thinks that the methodology and reasoning process of the other expert are superior to those of the first expert. This is especially true given that the expert’s view that a particular conclusion “fits” a particular case must itself •constitute scientific knowledge — a challenge to “fit” is very close to a challenge to the expert’s ultimate conclusion about the particular, case, and yet it is part of the judge’s admissibility calculus under Dau-bert. 35 F.3d at 746 (emphasis added). In a footnote, Judge Becker added that: The methodology/eonclusion distinction remains of some import, however, to the extent that there will be cases in which a party argues that an expert’s testimony is unreliable because the conclusions of an expert’s study are different from those of other experts. In such eases, there is no basis for holding the expert’s testimony inadmissible. 35 F.3d at 746 n. 15 (citations omitted). In Claar v. Burlington Northern R. Co., 29 F.3d 499 (9th Cir.1994), the Ninth Circuit emphasized that a district court is “both authorized and obligated to scrutinize carefully the reasoning and methodology” underlying the expert’s proffered testimony. 29 F.3d at 502 (emphasis added). According to the court in Claar: This requirement means that the court had to determine that [the experts] arrived at their conclusions using scientific methods and procedures, and that those conclusions were not mere subjective beliefs or unsupported speculation. 29 F.3d at 502 (emphasis added). More recently, in Lust v. Merrell Dow Pharmdceuticals, Inc., supra, the Ninth Circuit acknowledged that a district court need not ignore an expert’s anomalous conclusions in determining admissibility under Rule 702. In Lust, plaintiff’s expert, Dr. Done, proposed to testify that ingestion of the drug Clomid causes a substantial increase in the probability of all birth defects on the ground that human epidemiological studies and animal studies show an association between the drug and a wide variety of problems. Un-contradicted testimony from defendant’s expert, however, indicated that Done’s chief premise — that if there is evidence of a positive association between an agent and a wide variety of birth defects in human epidemiological and animal studies, then the agent substantially increases the probability of all types of birth defects — was not espoused by a relevant minority of teratologists. Lust, 89 F.3d at 596. The Ninth Circuit held that the district court properly excluded Done’s testimony. Responding to Done’s contention that the district court “violated Daubert’s command that “ ‘[t]he focus ... must be solely on principles and methodology, not on the conclusions that they generate,’ ” the court stated: Done’s conclusions did arouse the district court’s suspicion, but that is to be expected. When a scientist claims to rely on a method practiced by most scientists, yet presents conclusions that are shared by no other scientist, the district court should be wary that the method has not been faithfully applied. It is the proponent of the expert who has the burden of proving admissibility. To enforce this burden, the district court can exclude the opinion if the expert fails to identify and defend the reasons that his conclusions are anomalous. Lust, 89 F.3d at 598 (emphasis added; citation omitted). In a recent law review article evaluating the admissibility of scientific evidence after Daubert, the author suggests the following approach to the methodology/conclusion debate: Rule 702 seeks to ensure that there is a valid scientific connection to the pertinent inquiry, and scientific validity for one purpose is not necessarily scientific validity for other purposes. * * * In a case where a plaintiff alleges personal injury from exposure to a substance, the issue at hand is not whether the agent can potentially cause that injury. Rather, the issue is whether the agent caused the particular plaintiffs injury. To return to the animal study hypothetical, the court should not simply ask whether the type of animal study relied on by the expert can be validly used to determine whether Bendectin is a teratogen, but should also ask whether scientists reasonably rely on that type of animal study to prove that Bendectin is a teratogen in humans. If the answer is yes, the court should ask whether the animal study provides sufficient information to allow a scientist to reasonably rely on it to prove that Bendectin caused a birth defect in a particular individual. Finally, assuming those questions are answered to the court’s satisfaction, the ■ court must determine whether the expert’s principles and methodology are sound. In other words, has the expert properly extrapolated from the animal study at issue, or is her reasoning flawed? Some have argued that Daubert forbids courts to ask this question. * * * This reasoning is wrong-headed. When Daubert forbids courts to examine an expert’s conclusions, it is obviously alluding to the Frye rule. Some courts used Frye to exclude novel expert testimony if it conflicted with the established view in the scientific community, regardless of the soundness of the expert’s methodology and reasoning. That is no longer permissible after Daubert. But Daubert does demand that courts assess the scientific validity of the expert’s testimony. Daubert demands that in reviewing the expert’s principles and methodology, a court should determine whether “the principle supports what is purports to show.” * * * Daubert therefore not only allows, but requires, courts to determine whether an expert’s extrapolations from underlying studies or data are proper, or whether the expert has committed scientific or mathematical errors. David E. Bernstein, The Admissibility of Scientific Evidence After Daubert v. Merrell Dow Pharmaceuticals, Inc., 15 Cardozo L.Rev. 2139, 2165-66 (1994) (emphasis added; footnotes omitted). In Paoli II, 35 F.3d at 745, Judge Becker noted that Daubert’s requirement that the expert testify to scientific knowledge — conclusions supported by good grounds for each step in the analysis — means that any step that renders the analysis unreliable under the Dauberb factors renders the expert’s testimony inadmissible. This is true whether the step completely changes a reliable methodology or merely misapplies that methodology. (Emphasis in original; footnote omitted.) There appears to be no clear demarcation between scientific methodology and the conclusions it generates. Daubert I acknowledged this much, recognizing that science is a process, not “an encyclopedic body of knowledge.” 509 U.S. at 590, 113 S.Ct. at 2795 (citation omitted). This court need not and should not ignore any step in that process, but must ensure that in each step, from initial premise to ultimate conclusion, the expert faithfully followed valid scientific methodology. In other words, this court need not accept, as scientifically reliable, any conclusion thát good science does not permit to be drawn from the underlying data but which, instead, constitutes “unsupported speculation,” or, in the words of Dr. Stenzel-Poore, a “leap of faith.” The Ninth Circuit requires no less. See Claar, 29 F.3d at 502; see also Lust, 89 F.3d at 598. Accordingly, in resolving the pending issues before me, this court will examine the evidence to ensure, as Judge Becker noted in Paoli II, that every step in the expert’s reasoning process, including the expert’s formulation of conclusions, are grounded in good science. IY. FINDINGS AND CONCLUSIONS Physicians have used silicone products in the human body for various purposes since the 1950s. Medical devices made from hard silicone include shunts, finger joints, hip joints, and heart valves. In addition, the United States and Japan experimented with injecting liquid silicone' directly into the human body in the 1950s and 1960s. However, the FDA eventually classified silicone liquid directly injected as a drug and has approved it only for experimental investigations. The silicone- gel breast implants involved in this litigation consist of 80 to 90 percent liquid silicone combined with 10 to 20 percent silicone gel, contained in a silicone rubber shell. Plaintiffs’ theory of causation — or, as they refer to it, bioplausibility — begins with the premise that silicone from breast implants is released into a woman’s body, either through implant rupture or through “gel bleed,” the slow but continuous release of very small droplets (“mierodroplets”) of silicone gel through the silicone rubber implant cover. Once released into the body, plaintiffs assert, silicone migrates throughout the body, either by diffusing through cell membranes or by being carried by macrophages, the cells in a person’s body that devour and eliminate invading foreign bodies and wastes. In the process, the silicone degrades, or is chemically converted, into more reactive molecules such as silanols. The released silicone and the reactive products of silicone degradation purportedly elicit an autoimmune response from the woman’s immune system, essentially turning her immune system against her. The result, plaintiffs conclude, is general, systemic disease and particular signs and symptoms such as muscle and joint pain, headaches, rashes, and an inability to concentrate. Plaintiffs’ theory of causation thus brings four general areas of science into play: epidemiology; rheumatology; immunology/toxicology; and polymer chemistry. As has been described, the Rule 104 hearings and many of the parties’ arguments have been generally structured around these scientific fields. Thus, while I am mindful that the motions in limine actually address the exclusion of particular expert witnesses, my findings and conclusions will track the various disciplines at issue. A. Atypical Connective Tissue Disease Plaintiffs premise many of their claims on the existence of a variously-titled atypical connective tissue disease (ACTD). This “disease” allegedly manifests itself through a constellation of various symptoms and is allegedly caused by an autoimmune response to silicone from breast implants. Plaintiffs have offered Dr. Eric Gershwin and Dr. Kip Kemple as experts in rheumatology' to testify that silicone exposure is the probable cause of plaintiffs’ atypical constellation of symptoms. By definition, ACTD is not one of the classical autoimmune diseases, such as lupus, scleroderma, or rheumatoid arthritis. In addition, plaintiffs’ expert Dr. Goldsmith testified that ACTD does not exist even as a hypothesis yet. “Epidemiologically, the question that you have asked me twice is where we are with these atypical diseases. And I am telling you we are back at the beginning of formulating studiable hypotheses to test. We are really at the beginning of that.” TRANS. Of Pretrial Hearings before the Honorable Robert E. Jones (hereinafter Portland Trans.), Aug. 6, 1996, at 164:23 to 165:2. A silicone research group has proposed criteria for this alleged disease, but these criteria have not yet been tested, nor does the rheumatology community generally accept the existence of ACTD. Dr. Gershwin has acknowledged that he would not rely on these criteria as authoritative for his medical opinion. Portland Trans., Aug. 5, .1996, at 78:25 to 79:23. He also admitted that there is no specific diagnostic test for this alleged disorder. Portland Trans., Aug. 5,1996, at 88:1-4,15-19. Finally, women who allegedly have ACTD do not uniformly exhibit the same signs and symptoms, and there is no “signature” disorder to suggest either that the cause is silicone exposure or that the cause is the same for all women showing this constellation of symptoms. Instead, the asserted constellation of symptoms comprising ACTD overlaps significantly with those comprising chronic fatigue syndrome and fibromyalgia. , Because ACTD is at best an untested hypothesis, there is no scientific basis for any expert testimony as to its causes and presence in plaintiffs. Therefore, defendants’ motions are GRANTED as regards any expert testimony relating to the existence and causation of any atypical, silicone-caused, autoimmune disorder. With the possible exception of plaintiff LeaAnn Hall, moreover, plaintiffs have not been diagnosed as having classical autoimmune disorders. Therefore, the rest of this opinion will address expert testimony in regards to plaintiffs’ individual signs and symptoms. B. Epidemiology Plaintiffs offer Dr. David Goldsmith as an expert to testify that there is epidemiological and other scientific data showing that women with silicone breast implants have significantly elevated probability of suffering from classical diseases when compared to women without breast implants. In contrast, plaintiffs offer Dr. Shanna Swan, through transcripts of her previous testimony in other cases, to testify that no valid epidemiological studies regarding the relationship of silicone breast implants and disease have been completed as of August 1996. Epidemiology is the medical science devoted to determining the causes of disease in human beings. Epidemiologists compare control groups of unexposed individuals to groups of individuals exposed to a hypothetical cause of the disease being studied to determine whether exposed individuals have a greater risk of manifesting that disease. In epidemiological terms, any difference in risk of getting the disease between the two groups is the exposed individuals’ relative risk. The existence or nonexistence of relevant epidemiology can be a significant factor in proving general causation in toxic tort cases. Daubert II, 43 F.3d at 1320-21; Brock v. Merrill-Dow Pharmaceuticals, Inc., 874 F.2d 307, 311-13 (5th Cir.1989). To support admissible expert opinions, epidemiological evidence must fit the legal as well as the substantive issues of the case. Because this is a diversity action, Oregon substantive standards of law must apply. Erie Railroad Co. v. Tompkins, 304 U.S. 64, 58 S.Ct. 817, 82 L.Ed. 1188 (1938). As discussed above, under Oregon law, a plaintiff seeking to prove causation must “ ‘introduce evidence which affords a reasonable basis for the conclusion that it is more likely than not that the conduct of the ■ defendant was a substantial factor in the result.’” Griffin v. K.E. McKay’s Mkt., 125 Or.App. at 451-52, 865 P.2d 1320 (quoting Eitel v. Times, Inc., 221 Or. 585, 594, 352 P.2d 485 (1960)). This burden requires plaintiffs to demonstrate that exposure to breast implants more than doubled the risk of their alleged injuries. Daubert II, 43 F.3d at 1320. In epidemiological terms, Oregon’s standard of proof means that plaintiffs must be able to show a relative risk of greater than 2.0: The threshold for concluding that an agent was more likely the cause of a disease than not is relative risk greater than 2.0. Recall that a relative risk of 1.0 means that that agent has no effect on the incidence of disease. When the relative risk reaches 2.0, the agent is responsible for ah equal number of cases of disease as all other background causes. . Thus, a relative risk of 2.0 implies a 50% likelihood that an exposed individual’s disease was caused by the agent. Bailey, et al., Reference Guide on Epidemiology, REFERENCE MANUAL ON SCIENTIFIC EVIDENCE at 168. The Ninth Circuit has reached a similar conclusion under California’s standard of proof, which is very similar to Oregon’s, holding that “[f]or an epidemiological study to show causation under a preponderance standard,, ‘the relative risk of [the condition at issue] arising from the epidemiological data ... will, at minimum, have to exceed “2”.’ ” Daubert II, 43 F.3d at 1321 (quoting DeLuca v. Merrell Dow Pharmaceuticals, 911 F.2d 941, 958 (3d Cir.1990)). Although, as discussed above, epidemiological studies showing a relative risk of less than 2.0 might be relevant under some circumstances, here, as in Daubert II, “plaintiffs’ experts did not seek to differentiate these plaintiffs from the subjects of the statistical studies. The studies must therefore stand or fall on their own.” Id. at 1321 n. 16. Plaintiffs’ experts base their proffered expert opinions on the sixteen epidemiological studies assessing the relationship of silicone breast implants to classical connective tissue disease. In addition, plaintiffs have called this court’s attention to the 1996 Liang-Schottenfeld abstract recently presented at a meeting of the American College of Rheumatology that reports a relative risk of 2.27 for Undifferentiated Connective Tissue Diseases (UCTD). Dr. Goldsmith testified in the proceedings before this court that he was not willing to testify, based on the 16 then-available studies, that silicone more likely than not could cause disease in women. That testimony was as follows: DR. GREENLICK: You were asked a question if you had an opinion on causality based on whatever other evidence was left, case studies, other animal evidence. I think there is a sense that when you talked about there was a suggestion from some of the things that would mean you had a very low certainty of causality and that causality could go from saying, “We don’t know if there’s any link at all,” all the way to saying, “We are really quite certain, short of randomly implanting women, we are very certain.” Given the fact that there is no epidemiological data on this, where would you say your sense of certainty of your causality is? How close to zero as opposed to 100 percent are you? Are you in certainty with your opinion that there is a causal relationship with breast implants and atypical connective tissue disease? DR. GOLDSMITH: Let me also make sure that I give you an answer that I think is reflective of the — of the question in front of us. I don’t believe it should go from zero to — to fully sure. I think it’s also possible that breast implants could, in fact, be negatively related to those atypical syndromes as well. DR. GREENLICK: Right. I was just starting from a zero, yes, could you have gone all the way from they are highly protective through no relationship, all the way to certain causality. But let’s just — I assume you don’t — you are not suggesting that the current data would tell you they are protective against atypical disease. So let’s start from zero at “I have no certainty whatever there’s a relationship,” all the way to “I am absolutely certain there’s a relationship from the existing data given no epidemiological data.” I was wondering where you would— DR. GOLDSMITH: At the moment, I must suggest to you that the evidence looks to me as if it’s just that, that it’s a possibility, and I would have to characterize it as less than 50 percent. That would be where I am at the moment. But where the new evidence is going to show that there is or is not an association, I think we have to wait for the science to tell us. We have to wait for the epidemiology. PORTLAND Trans., Aug. 6, 1996, at 241:14 to 243:4 (emphasis added). With the release of the Liang-Schottenfeld abstract, Dr. Goldsmith now indicates a willingness to testify that such causation is “more likely than not.” This court cannot accept his proffered change in testimony because it finds the methodology supporting this changed testimony unreliable under Daubert I and Daubert II. First, none of the- 16 epidemiological studies found that women with silicone breast implants faced a relative risk of classical diseases or disease signs and symptoms of anywhere near 2.0. Indeed, only one study — the Hennekens study — found any statistical relationship between the presence of silicone breast implants and disease, and there the relative risk was only 1.24. Therefore, these studies cannot support expert testimony that silicone “more likely than not” causes disease or signs and symptoms of disease in women. Second, the Liang-Schottenfeld abstract cannot in itself support Dr. Goldsmith’s change in testimony. The abstract is not yet published, nor is a full write-up of the study, including the supporting data, yet available. Indeed, Dr. Goldsmith admitted in his New York testimony that his only knowledge of the details of the study came from a telephone inquiry. New YorK Trans., at 71:17-24. According to the abstract, moreover, the study included only three women with breast implants, calling its epidemiological significance severely into question. In addition, the abstract explicitly concludes that “silicone breast implants were not significantly associated with UCTD,” suggesting that silicone gel breast implants are not associated with disease. In contrast, the abstract concludes overall that, “[ajmong all types of implanted devices, including breast implants, both those containing silicone * * * and those that did not contain silicone * * * were significantly associated with UCTD.” This apparent internal contradiction within the abstract’s conclusions calls the value of this study further into question. In light of these shortcomings and in the face of the other 16 studies, which Dr. Goldsmith has already admitted do not support expert testimony that silicone “more likely than not” causes disease in women, this court GRANTS defendant’s motion to exclude Dr. Goldsmith’s epidemiological testimony. As for defendants’ motion to exclude Dr. Swan’s proffered testimony, the motion must be GRANTED because Dr. Swan’s testimony is unreliable and no longer “fits” plaintiffs’ theory of the case. I first note that several courts have rejected Dr. Swan’s testimony and her “reanalysis” approach as unreliable. Dr. Swan’s reanalysis of the silicone epidemiology has never been subjected to peer review. Merlin HEARING TRANS., at 73-76. Moreover, her theory has not been espoused by any other scientist whose work has been subjected to the peer review process. Merlin Hearing Trans., at 73-74. Peer review and publication weigh heavily in the calculus of the reliability of expert testimony because such peer review “increases the likelihood that substantive flaws in methodology will be detected.” Daubert I, 509 U.S. at 594, 113 S.Ct. at 2797. Thus, the lack of peer review for Dr. Swan’s theories weighs heavily against the admissibility of Dr. Swan’s testimony. In addition, Dr. Swan’s testimony involves only her opinions and criticisms of others’ work; as such, it is-not based on any technique that can be scientifically tested. Moreover, her criticisms of the existing epidemiology for silicone gel breast implants have not been generally accepted. In fact, they have not been accepted at all. Merlin Hearing Trans., at 92-93. In contrast, Dr. Swan admits that no studies have established a causal link of any scientific significance between silicone breast implants and disease, Merlin Hearing Trans., at 82, and this is the reeog-nized consensus of the relevant scientific community. As the Supreme Court stated, “widespread acceptance can be an important factor in ruling particular evidence admissible, and a known technique that has been able to attract only minimal support within the community may properly be viewed with skepticism.” Daubert I, 509 U.S. at 594, 113 S.Ct. at 2797. Many courts have recognized that an unexplained conflict with the generally accepted methodology or theories in a given scientific field can be a basis for excluding proffered expert testimony. See Turpin v. Merrell Dow Pharmaceuticals, Inc., 959 F.2d 1349, 1360 (6th Cir.), cert. denied, 506 U.S. 826, 113 S.Ct. 84, 121 L.Ed.2d 47 (1992) (finding no scientific basis for testimony of a causation expert who did “not testify on the basis of the collective view of his scientific discipline^ nor [did] he take issue with his peers and explain the grounds for his difference”); O’Conner v. Commonwealth Edison Co., 807 F.Supp. 1376, 1398 (D.Ill.1992), aff'd 13 F.3d 1090 (7th Cir.), cert. denied — U.S. -, 114 S.Ct. 2711, 129 L.Ed.2d 838 (1994) (holding that “an expert opinion that actually contradicts directly the scientific consensus is inadmissible”); Conde v. Velsicol Chem. Corp., 804 F.Supp. 972, 1024 (S.D.Ohio 1992), aff'd 24 F.3d 809 (holding that “when an expert expresses an opinion which is not generally accepted within the medical and scientific communities, he has an obligation to provide a reasoned explanation of why his methodology and opinions differ”). In addition to not being peer-reviewed and to being untestable, Dr. Swan’s proffered testimony inexplicably conflicts with the general consensus of the epidemiological community. Thus, it is unreliable and hence inadmissible. In addition, Dr. Swan’s testimony has no “fit.” As discussed above, even if the proponents of expert testimony establish that that testimony is reliable scientific knowledge, the court must still exclude the evidence if it does not fit the issues to be decided in the case. Daubert I, 509 U.S. at 591, 113 S.Ct. at 2795-96. In the Ninth Circuit, testimony only “fits” a ease if it logically advances a material aspect of the proponent party’s case. Daubert II, 43 F.3d at 1315. Here, Dr. Swan seeks to testify that current epidemiology regarding the relationship of silicone breast implants and classical disease is invalid. However, this court has already determined that the proffered testimony based on that epidemiology is inadmissible, and it will determine, see discussion below, that plaintiffs cannot base their entire case on differential diagnosis. In addition, to the extent that plaintiffs intended to use Dr. Swan’s testimony to support their argument that silicone breast implants can cause ACTD, I have already ruled that no- testimony regarding ACTD will be permitted. Therefore, Dr. Swan’s testimony is now a stepping stone that leads nowhere; it no longer “fits” plaintiffs’ case. There is no doubt but that Dr.- Swan has impressive credentials, as Justice Black-mun himself recognized in Daubert I, 509 U.S. at 583 n. 2, 113 S.Ct. at 2792 n. 2 (noting that Dr. Swan has “a master’s degree in biostatics from Columbia University and a doctorate in statistics from the University of California at Berkeley, is chief of the section of the California Department of Health and Sciences that determines causes of birth defects, and has served as a consultant to the World Health Organization, the Food and Drug Administration,, and the National Institutes of Health.”) However, as Judge Wein-stein noted in the Agent Orange litigation, the jury should “not be permitted to be misled by the glitter of an expert’s accomplishments outside the courtroom” if the expert opinion is based on “untrustworthy” data or is otherwise not reliable. , In re “Agent Orange” Product Liability Litigation, 611 F.Supp. 1223, 1245 (E.D.N.Y.1985) (citations omitted). As in that ease, “‘the speculation and unfounded assumptions underlying [the] testimony [of Dr. Swan] decrease its probative value, perhaps to the level of the gossamer.’ ” Id. at 1256 (quoting American Bearing Co. v. Litton Indus., Inc., 729 F.2d 943, 950 n. 14 (3d Cir.1984)). In this litigation, Dr. Swan’s well-traveled opinions are no more than educated guesses dressed up in evening clothes. Therefore, for all of the above reasons, I GRANT defendants’ motions to exclude Dr. Swan’s testimony. C. Immunology and Toxicology Plaintiffs have offered Dr. Eric Gershwin as an expert in immunology to testify that silicone is capable of causing plaintiffs’ constellation of symptoms because (1) silicone in contact with human tissue results in chronic inflammation through immune activation and cellular reactions; (2) silicone is an immune adjuvant and thus can produce enhanced immune responses when in the presence of a triggering condition and exacerbate existing immune-mediated conditions; and (3) the surface of silicone changes or degrades in vivo into silanol groups and/or silica. He relies on the epidemiological studies discussed above, his own clinical experience, biomarker, immune activation, and toxicological studies, and the work of the Harvard NMR Center on the degradation of silicone as the bases of his proffered opinion. Plaintiffs also offer Dr. Kip Kemple to testify that silicone can produce an immunological response in women. Dr. Kemple relies on immunological studies showing that autoantibodies are elevated in women with breast implants and his own study of anti-ganglioside antibodies in women with breast implants. The court submitted immunological/toxicological issues to its expert, Dr. Mary Stenzel-Poore, who specifically looked at the adju-vant potential of silicone gel implants, the potential for immune stimulation of T cells by silicone gel implants, altered natural, killer cell activity, and immune system cancer formation in rodents. She opined that the studies relied upon by plaintiffs’ experts justified the following conclusions regarding silicone gel adjuvant potential: la. Silicone gel emulsified with antigen may act as an adjuvant in humoral and cell-mediated immune responses in rodents. lb. Silicone oils that are both linear and low molecular weight, emulsified with antigen do not act as adjuvants in rodents. le. Silicone oils that are low molecular weight and cyclic (D4) emulsified with antigen may act as adjuvants. Appendix D, at 2. However, “[djirect attempts to demonstrate that immunization with these agents emulsified with ‘auto-antigens’ or given in the absence of antigens failed to show evidence of autoimmune disease despite obvious disease induction by Freund’s adjuvant,” except in a genetic strain of rat developed to have a high susceptibility of developing arthritis. Id. Thus, in rodents only, “enhanced immune responses are not found if the antigen is not emulsified with the silicone agents * * Id. at 2-3 (citations omitted). Dr. Stenzel-Poore 'further stated that “[fjorming the conclusion that elicitation of autoimmune and/or inflammatory disease occurs in women with SBI based on the evidence that silicone gel acts as an adjuvant when emulsified with antigen is unsupported by the data since peer-reviewed, studies failed to show evidence of any autoimmune-mediated disease.” Appendix D, at 3. Although “[t]he scientific methodology used in the aforementioned studies is generally sound,” - Dr. Gershwin’s opinion regarding the adju-vant properties of silicone gel requires a substantial leap of faith since it is undeter.mined from these studies whether silicone gel breast implants would lead to adjuvant actions, much less autoimmune responses or systemic inflammation; indeed, studies designed to test this hypothesis argue against such an outcome. Thus, the position of Dr. Gershwin is not well-supported by the data available in the published scientific literature nor is it derived from valid conclusions of the studies cited above. Id. (emphasis added). With regard to T-cell stimulation, Dr. Stenzel-Poore opined that “[t]he view that SBIs stimulate antigen-specific T cell mediated responses in vivo is not well substantiated by the experimental studies reported in the literature.” Appendix D, at 4. Moreover, although “[s]everal studies have been performed attempting to establish a link between silicone breast implantation in women and silicone-specific T-cell responses,” “these studies have a number of methodological shortcomings and thus should not form the basis of an opinion.” Id. at 5. As a result, those opinions of Dr. Gershwin regarding the role of silicone gel breast implants in stimulating specific T cell immunity and thereby providing a plausible mechanism of autoimmune induction are not upheld by the literature discussed above. The position of Dr. Gershwin is simply not well-supported by studies available in the published scientific literature nor is it derived from appropriate conclusions regarding the studies cited above. Id. at 8. Dr. Stenzel-Poore also examined the literature regarding changes in natural killer cell function. . She noted that “[c]hanges in natural killer (NK) cell function have been reported to be associated with silicone gel exposure in rodents and humans.” Appendix D, at 9. Such an association could be significant because “changes in NK cells have also been associated with increased susceptibility to pathogens and tumor formation.” Id. However, “[g]iven the concerns raised by the degree of irreproducibility and fluctuations in time and dose-dependency [in the silicone gel/NK cell studies], conclusions made regarding the suppressive effect of silicone gel on NK function based on these studies are premature.” Id. Moreover, “although the data indicate that 50% of symptomatic women with implants had lower NK activity prior to removal of the implant, it is misleading since the degree of variation is not shown in the implanted women, or in women without implants. It is invalid to conclude that silicone-gel breast implants in women lead to a depressed NK cell activity that is reversible with explanation.” Id. at 10. Finally, in evaluating the studies evaluating the development of immune system cancer in response to silicone, Dr. Stenzel-Poore stated that “Dr. Gershwin’s opinions regarding the development of immune system cancers in women with silicone breast implants is unwarranted” from the current studies, which are all animal studies. Appendix D, at 11. “There is no conclusive evidence to date that this model of tumor formation in mice has any human correlate.” Id. I agree with and accept Dr. Sten-zel-Poore’s assessments of Dr. Gershwin’s scientific methodology in fight of legal standards for Daubert hearings. As a preliminary matter, I note that most if not all of the studies that Dr. Gershwin and Dr. Kemple rely upon are animal studies (generally involving rodents), case reports or collections of case reports, and/or studies involving crystalline silica. Extrapolations of animal studies to human beings are generally not considered reliable in the absence of a scientific explanation of why such extrapolation is warranted. See Viterbo v. Dow Chemical Co., 826 F.2d 420 (5th Cir.1987) (excluding the evidence where there was only a single animal study of picloram and it showed a link to a disease completely different than plaintiffs diseases); Richardson v. Richardsort-Merrell, Inc., 857 F.2d 823, 830 (D.C.Cir.1988) (excluding animal studies of Bendeetin because of the overwhelming body of contrary epidemiological evidence and the admissions of the expert that animal studies merely raise a suspicion of causation in humans); Lynch v. Merrell-National Laboratories, 830 F.2d at 1194 (excluding animal studies of Bendeetin where they stood in the face of significant contrary epidemiological data); Turpin v. Merrell Dow Pharmaceuticals, Inc., 959 F.2d at 1360 (excluding testimony where the record failed to make clear how the animal studies were sufficient to show that Bendeetin causes birth defects more probably than not). Plaintiffs offer no explanation of why extrapolations from the rodent studies their experts rely upon to humans are warranted here. Similarly, case reports and case studies are universally regarded as an insufficient scientific basis for a conclusion regarding causation because case reports lack controls. Casey v. Ohio Medical Products, 877 F.Supp. 1380 (N.D.Cal.1995); Muzzey v. Kerr-McGee Chemical Corp., 921 F.Supp. 511, 519-20 (N.D.Ill.1996); In re Three Mile Island Litigation Cases Consolidated II, 911 F.Supp. 775, 795-96 (M.D.Penn.1996); Grimes v. Hojfmann-LaRoche, Inc., 907 F.Supp. S3, 35 n. 2 (D.N.H.1995). Therefore, these cannot be the basis of an opinion based on scientific knowledge under Daubert. Third, as will be discussed below, studies based on crystalline silica cannot support the testimony of plaintiffs’ experts because plaintiffs make no showing that silicone breast implants are associated with the presence of crystalline silica in women. In other words, the purported disease-causing agent in the silica studies has not been show to be scientifically relevant regarding the purported disease-causing agent — namely, silicone gel — in these cases. Finally, Daubert’s establishment of the court as gatekeeper requires that proffered scientific expert opinions that make too great a leap of faith from the scientific knowledge currently available be excluded. As . discussed above, an evaluation of whether scientific methodology is valid for Daubert purposes should include an examination of how the proffered conclusions relate to the bases upon which the expert relies. The court’s neutral technical advisor has advised that Dr. Gershwin — and, by implication, Dr. Kemple, who relies on most if not all of the same studies as Dr. Gershwin — has made too great a leap f