Valentine v. PPG Industries, Inc.

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[EDITORS' NOTE: THIS PAGE CONTAINS HEADNOTES. HEADNOTES ARE NOT AN OFFICIAL PRODUCT OF THE COURT, THEREFORE THEY ARE NOT DISPLAYED.] {¶ 1} Linda Valentine appeals the trial court's summary judgment in PPG Industries Ohio, Inc.'s favor and various discovery orders. She contests the court's determination that she failed to establish a right to participate in the workers' compensation system for the death of her husband, David Valentine ("Valentine"). Specifically, she asserts that the court improperly found her experts' opinions regarding proximate cause to be unreliable and, thus, inadmissible. Without expert testimony, the court concluded that no genuine issue of material fact remained concerning whether Valentine's workplace exposure to various toxic substances proximately caused his brain cancer (glioblastoma multiforme) and subsequent death.

{¶ 2} She presents four arguments to support her contention that the court incorrectly determined that no genuine issue of fact exists regarding proximate cause: (1) the court failed to consider her three experts' affidavits, (2) the court wrongly concluded that her medical experts' opinions were unreliable and inadmissible, (3) the court improperly determined that her experts' testimony did not show general causation between the decedent's brain tumor and his exposure to carcinogens in the workplace, and (4) the court imposed an incorrect standard of causation under the workers' compensation statute to determine whether a claimant can establish an occupational disease.

{¶ 3} Initially, we conclude that the trial court properly applied traditional tort standards of proximate cause in analyzing the connection between workplace exposure and the occurrence of an occupational disease. Accordingly, we reject the appellant's contention that in order to establish causation, a worker need only establish that a workplace exposure increased the risk of contracting a disease above that of the general population. Furthermore, after carefully reviewing the legal landscape concerning the reliability of expert testimony and the scientific literature that formed the basis of her experts' opinions, we conclude that the trial court did not abuse its discretion by rejecting this testimony. Without their opinions, appellant possessed no evidence to establish that Valentine's workplace exposure to toxic substances caused his brain tumor. Thus, appellant's failure to show proximate cause as an element of her workers' compensation claim is fatal to her claim, and the trial court appropriately entered summary judgment in PPG's favor. Because her remaining arguments are moot, we affirm the trial court's decision.

BACKGROUND {¶ 4} Valentine worked at the PPG Circleville facility from 1969 until 1997, initially as a lab technician and later as an environmental and wastewater-treatment specialist. During his employment Valentine was exposed to various chemicals. In 1997, Valentine was diagnosed with "glioblastoma multiforme," a rare form of brain cancer that accounts for only two to three percent of all new cancers diagnosed in the United States. The only medically proven cause of glioblastoma multiforme is ionizing radiation. Valentine received treatment for his brain tumor at the Ohio State University Hospital, where he saw Dr. Herbert Newton, Arthur James Cancer Research Center Director, and Dr. Michael Miner, Department of Neurosurgery Chairman. Despite their treatment, Valentine unfortunately died in 1999 at the age of 51.

{¶ 5} In November 1999, Mrs. Valentine filed a claim for death benefits with the Bureau of Workers' Compensation. She claimed that Valentine's exposure to a toxic brew of chemicals throughout his career at PPG caused him to contract the glioblastoma multiforme that led to his death. Ultimately, the bureau denied the claim.

{¶ 6} In August 2000, Mrs. Valentine filed an administrative appeal in the common pleas court. After lengthy and contentious discovery, PPG filed a summary judgment motion, arguing that no genuine issues of material fact existed concerning whether Valentine's work environment proximately caused his brain tumor. Appellee insisted (1) that the opinions of appellant's experts (Drs. Miner and Newton and industrial hygienist Norman Brusk) were inadmissible because they were not scientifically reliable and (2) that without these opinions, appellant had no evidence regarding proximate cause. Appellee contended that the experts' testimony was unreliable because no scientific discipline has established that a specific chemical agent or combination of chemical agents can cause a brain tumor in humans. The trial court agreed and concluded that without their testimony, no genuine issue of material fact remained regarding proximate cause, so the court granted PPG summary judgment.

{¶ 7} Mrs. Valentine timely appealed the trial court's judgment and raises the following assignments of error:

First Assignment of Error. It was an abuse of discretion for the trial court to grant appellee's motion for summary judgment without examining and analyzing the affidavit evidence of appellant's three experts.

Second Assignment of Error. The trial court erred in holding that the opinions of appellant's medical experts were unreliable and therefore inadmissible pursuant to Rule 702.

Third Assignment of Error. The trial court erred in ruling as a matter of law that appellant's experts failed to establish general causation between David Valentine's exposure to carcinogens in his workplace and the development of his brain tumor.

Fourth Assignment of Error. The trial court erred in its assessment of the proof necessary to establish an occupational disease as defined by the workers' compensation statute.

Fifth Assignment of Error. The trial court erred in limiting appellant's discovery on the following matters:

A. Failure to order suspension of the appellee's "retention of records policy" so as to prevent destruction of relevant documents.

B. Limitation on production of exposure records, air sample tests, and ventilation records to only those records taken in the laboratories rather than the production areas.

C. Failure to order appellee to release patent information for materials manufactured during David Valentine's employment.

D. Denial of appellant's request for production of e-mail communications and any other written communications from the appellee's research and development department in Pennsylvania to appellee's industrial hygienists.

E. Denial of appellant's request for review of OSHA and EPA records pertaining to the operation of appellee's Circleville plant.

F. Failure of the court to order the completion of depositions of appellee's industrial hygienists, Lewis Jordan and Nick Cleary, to answer questions on the presence of a risk of cancer from chemicals in the appellee's workplace.

G. Failure of the court to order the release of the ENSR computerized data and imposition of a ten-day time limit for the appellant to commit to full payment of unspecified expenses.

H. Failure of the court to require the appellee to provide affidavits that identify the appropriate individuals with the corporation that carried out discovery searches and to document what efforts have been taken to find the documents ordered released.

I {¶ 8} Appellant directs her first four assignments of error to the trial court's decision granting appellee summary judgment. First, she asserts that the trial court erred by failing to consider her three experts' affidavits when ruling on appellee's summary judgment motion. Second, appellant contends that the trial court erred by concluding that Dr. Miner's and Dr. Newton's testimony regarding the proximate cause of Valentine's brain tumor was not reliable and, therefore, inadmissible. Appellant argues that the court misinterpreted Evid.R. 702 and the evidence she submitted. Third, appellant argues that the trial court erred by concluding that her experts failed to establish general causation linking the exposure to carcinogens in the workplace to the development of brain cancer. Fourth, appellant contends that the trial court erred by determining that appellant was required to establish causation between specifically identified chemicals and brain tumors to a degree of medical or scientific certainty.

{¶ 9} As a prelude to addressing appellant's contention that the trial court applied an improper legal standard of causation, we set forth some general principles governing summary judgment proceedings and the workers' compensation statutes.

A. Summary Judgment Standard {¶ 10} We review a trial court's decision to grant summary judgment on a de novo basis. See, e.g., Grafton v. Ohio EdisonCo. (1996), 77 Ohio St. 3d 102, 105, 671 N.E.2d 241. Accordingly, we conduct an independent review of the record and afford no deference to the trial court's determination. See, e.g., Brownv. Scioto Cty. Bd. of Commrs. (1993), 87 Ohio App. 3d 704, 711,622 N.E.2d 1153. Under Civ.R. 56(C), summary judgment is appropriate when (1) no genuine issue as to any material fact remains to be litigated, (2) the moving party is entitled to judgment as a matter of law, and (3) it appears from the evidence, when viewed most strongly in favor of the nonmoving party, that reasonable minds can come to a conclusion only in favor of the moving party. See, e.g., Grafton, supra. The burden of showing that no genuine issue exists as to any material fact falls upon the moving party. See, e.g., Mitseff v. Wheeler (1988), 38 Ohio St. 3d 112, 115, 526 N.E.2d 798. If the moving party satisfies this burden, "the nonmoving party then has a reciprocal burden outlined in Civ.R. 56(E) to set forth specific facts showing that there is a genuine issue for trial, and if the nonmovant does not so respond, summary judgment, if appropriate, shall be entered against the nonmoving party." Kulch v.Structural Fibers, Inc. (1997), 78 Ohio St. 3d 134, 145,677 N.E.2d 308, citing Dresher v. Burt (1996), 75 Ohio St. 3d 280,295, 662 N.E.2d 264. B. Workers' Compensation {¶ 11} Every employee who is injured or contracts an occupational disease in the course of employment is entitled to receive compensation under R.C. 4123.54. Courts must liberally construe the workers' compensation laws in favor of employees. R.C. 4123.95; Bailey v. Republic Engineered Steels, Inc. (2001), 91 Ohio St. 3d 38, 40, 741 N.E.2d 121. In Bailey, the court explained that liberal construction of the workers' compensation laws require courts to adopt "the most comprehensive meaning of the statutory terms." Id. The court stated: "A liberal construction has been defined as giving ``generously all that the statute authorizes,' and ``adopting the most comprehensive meaning of the statutory terms in order to accomplish the aims of the Act and to advance its purpose, with all reasonable doubts resolved in favor of the applicability of the statute to the particular case. Interpretation and construction should not result in a decision so technical or narrow as to defeat the compensatory objective of the Act.' Fulton, Ohio Workers' Compensation Law (2 Ed. 1998) 9, Section 1.7." Bailey, 91 Ohio St.3d at 40,741 N.E.2d 121.

{¶ 12} Although a court must liberally construe the workers' compensation laws in favor of the injured employee, a court may not "``read into the statute something which cannot reasonably be implied from the language of the statute.'" Phillips v.Borg-Warner Corp. (1972), 32 Ohio St. 2d 266, 268, 61 O.O.2d 493,291 N.E.2d 736, quoting Szekely v. Young (1963),174 Ohio St. 213, 22 O.O.2d 214, 188 N.E.2d 424, paragraph two of the syllabus.

{¶ 13} R.C. 4123.01(F) defines an "occupational disease" as one that satisfies the following three elements: "(1) the disease is contracted in the course of employment; (2) the disease is peculiar to the claimant's employment by its causes and the characteristics of its manifestation or the conditions of the employment result in a hazard which distinguishes the employment in character from employment generally; and (3) the employment creates a risk of contracting the disease in a greater degree and in a different manner than in the public generally." See, also,State ex rel. Ohio Bell Tel. Co. v. Krise (1975),42 Ohio St. 2d 247, 71 O.O.2d 226, 327 N.E.2d 756, syllabus.

C. Proximate Cause {¶ 14} Appellant contends that the liberal nature of workers' compensation laws requires us to lower the standard for admitting expert testimony or to lower the standard for proving proximate cause. Regrettably, we cannot agree. While workers' compensation statutes should be liberally construed in favor of the injured worker, this does not mean we are free to ignore the legal principles that control the admissibility of expert testimony and the pronouncements of the Supreme Court of Ohio on proximate cause.

{¶ 15} In order to demonstrate that the employee contracted the disease while in the course of employment, the employee must prove that the occupational disease proximately resulted from employment. See State ex rel. Ohio Bell Tel. Co. v. Krise,42 Ohio St.2d at 254, 71 O.O.2d 226, 327 N.E.2d 756 ("the basic subject matter [of the first element of an occupational-disease claim] is causation"); see, also, Hutchinson v. Ohio FerroAlloys Corp. (1994), 70 Ohio St. 3d 50, 52, 636 N.E.2d 316 ("Proof of the three definitional criteria of ``occupational disease' — causal connection, hazard and risk — creates a compensable claim"); Cook v. Mayfield (1989),45 Ohio St. 3d 200, 204, 543 N.E.2d 787; Fox v. Indus. Comm. (1955),162 Ohio St. 569, 576, 55 Ohio Op. 472, 125 N.E.2d 1, paragraph one of the syllabus; Sheeler v. Ohio Bur. of Workers' Comp. (1994),99 Ohio App. 3d 443, 451, 651 N.E.2d 7 (noting that in Fox the court "held that, in order to establish a right to workers' compensation, a claimant must show by a preponderance of the evidence that a direct or proximate causal relationship existed between his employment and the disability sustained").

{¶ 16} "The proximate cause of an event is that which in a natural and continuous sequence, unbroken by any new, independent cause, produces that event and without which that event would not have occurred." Aiken v. Indus. Comm. (1944), 143 Ohio St. 113,117, 28 Ohio Op. 50, 53 N.E.2d 1018. "The definition of and principles governing * * * the determination of ``proximate cause' in the field of torts are applicable" in workers' compensation cases. Murphy v. Carrollton Mfg. Co. (1991), 61 Ohio St. 3d 585,587, 575 N.E.2d 828, citing Aiken, 143 Ohio St. 113, 28 Ohio Op. 50, 53 N.E.2d 1018, syllabus; and Oswald v. Connor (1985),16 Ohio St. 3d 38, 42, 16 OBR 520, 476 N.E.2d 658; see, also, Clickv. S. Ohio Correctional Facility, 152 Ohio App. 3d 560,2003-Ohio-2208, 789 N.E.2d 643, at ¶ 8. Thus, we are forced to reject appellant's contention that the trial court improperly applied standard principles of tort law to the context of a worker's compensation claim.

{¶ 17} To prove the proximate cause of a medical condition, here, a brain tumor, expert medical testimony ordinarily is necessary. See, e.g., Darnell v. Eastman (1970),23 Ohio St. 2d 13, 52 O.O.2d 76, 261 N.E.2d 114, syllabus. Furthermore, to prove that a toxic substance caused the plaintiff's medical condition, the plaintiff must establish both (1) that the toxic substance is capable of causing the condition (general causation) and (2) that the toxic substance in fact caused the plaintiff's medical condition (specific causation).¹ See, generally, Downs v. Perstorp Components, Inc. (1999), 126 F. Supp. 2d 1090,1095; Hall v. Baxter Healthcare Corp. (D.Or. 1996),947 F. Supp. 1387. Expert testimony ordinarily will be required to prove both general and specific causation.

{¶ 18} Appellant cites Olinger v. Pretty Products, Inc. (Nov. 7, 1997), Coshocton App. No. 96-CA-29, as support for her argument that the burden of proof regarding causation in tort cases is not applicable to an occupational-disease claim in the workers' compensation context. In Olinger, the court stated: "Throughout its brief, appellant consistently misstates the law in Ohio concerning the of a [sic] cause of action for recovery of workers' compensation benefits for an occupational disease. Appellant cites cases concerning proof of causation in a tort action. The instant action is not based on tort. An occupational disease is compensable under R.C. 4123.68(BB) where the following criteria exist: (1) the disease is contracted in the course of employment, (2) the disease is peculiar to the claimant's employment by its causes and the characteristics of its manifestation, or the conditions of employment result in a hazard which distinguishes the employment in character from employment generally, and (3) the employment creates a risk of contracting the disease in a greater degree and in a different manner than the public generally."

{¶ 19} Based on Ohio's unique statutory scheme, the Olinger court went further and rejected the requirement that a claimant must establish both general and specific causation in order to participate in the fund. Unfortunately, Olinger is neither persuasive nor controlling in light of the Ohio Supreme Court's pronouncement that the definition and principles governing proximate cause in tort actions are equally applicable in workers' compensation cases. Murphy, 61 Ohio St.3d at 587,575 N.E.2d 828; Oswald v. Connor, supra; Aiken v. Indus. Comm., supra. In fact, our research failed to reveal a single Ohio case that cites Olinger, with approval or otherwise.

{¶ 20} Appellant construes the statutory requirement that a claimant must establish a risk of contracting a disease that is greater that that of the public generally as a liberalized causation standard. We disagree. The requirement dealing with comparative risk is simply a necessary predicate to participation in the worker's compensation system; it is a definitional component of the term "occupational disease" that is intended to ensure that the injury to be compensated is truly workplace-related. The Supreme Court's ruling in Murphy negates the contention that it is intended to abrogate the standard principles of proximate cause that require proof of both general and specific causation within a reasonable degree of expert certainty. While we concede that appellant's argument is appealing, we cannot adopt it in light of Murphy.² Appellant's fourth assignment of error is meritless.

II. Admissibility of Expert Testimony {¶ 21} Apologetically, we now turn to an extended discussion of expert testimony, which must comply with Evid.R. 702 to be admissible during summary judgment proceedings. "Pursuant to Civ.R. 56(C), a court may not consider any evidence when ruling on a motion for summary judgment unless it conforms with Civ.R. 56." Douglass v. Salem Community Hosp., 153 Ohio App. 3d 350,2003-Ohio-4006, 794 N.E.2d 107, at ¶ 21. According to Civ.R. 56(E), "[s]upporting and opposing affidavits shall be made on personal knowledge, shall set forth such facts as would be admissible in evidence, and shall show affirmatively that the affiant is competent to testify to the matters stated in the affidavit." Thus, affidavits containing opinions must meet the requirements in the Rules of Evidence governing the admissibility of opinions. See Tomlinson v. Cincinnati (1983),4 Ohio St. 3d 66, 4 OBR 155, 446 N.E.2d 454, paragraph one of the syllabus; see, also, Douglass.

{¶ 22} The trial court has broad discretion in determining the admissibility of expert testimony, and we may reverse only if the trial court abused its discretion. See Kumho Tire Co. v.Carmichael (1999), 526 U.S. 137, 152-153, 119 S. Ct. 1167,143 L. Ed. 2d 238; see, also, Miller v. Bike Athletic Co. (1998),80 Ohio St. 3d 607, 616, 687 N.E.2d 735. "Abuse of discretion" implies that a court acted in "an unreasonable, arbitrary, or unconscionable manner." See, e.g., State ex rel. Sartini v.Yost, 96 Ohio St. 3d 37, 2002-Ohio-3317, 770 N.E.2d 584, at ¶ 21;State v. Herring (2002), 94 Ohio St. 3d 246, 255,762 N.E.2d 940; Blakemore v. Blakemore (1983), 5 Ohio St. 3d 217, 219, 5 OBR 481, 450 N.E.2d 1140. An abuse of discretion amounts to more than an error of judgment and instead equates to "perversity of will, passion, prejudice, partiality, or moral delinquency."Pons v. Ohio State Med. Bd. (1993), 66 Ohio St. 3d 619, 621,614 N.E.2d 748. Furthermore, when applying the abuse-of-discretion standard, an appellate court may not substitute its judgment for that of the trial court. See, e.g., Berk v. Matthews (1990),53 Ohio St. 3d 161, 169, 559 N.E.2d 1301.

{¶ 23} In general, courts should admit expert testimony whenever it is relevant and satisfies Evid.R. 702. State v.Nemeth (1998), 82 Ohio St. 3d 202, 207, 694 N.E.2d 1332; see, also, State v. Williams (1983), 4 Ohio St. 3d 53, 58, 4 OBR 144, 446 N.E.2d 444. Thus, the trial judge must perform a "gatekeeping" role to ensure that expert testimony is sufficiently (a) relevant and (b) reliable to justify its submission to the trier of fact. See Kumho Tire,526 U.S. at 152, 119 S. Ct. 1167, 143 L. Ed. 2d 238; Daubert v. Merrell DowPharmaceuticals, Inc. (1993), 509 U.S. 579, 589, 113 S. Ct. 2786,125 L. Ed. 2d 469; Nemeth, 82 Ohio St.3d at 211, 694 N.E.2d 1332;Douglass, 153 Ohio App. 3d 350, 2003-Ohio-4006, 794 N.E.2d 107, at ¶ 32.

{¶ 24} In performing its gatekeeping function, the trial court's starting point should be Evid.R. 702, which provides that a witness may testify as an expert if all of the following apply: "(A) The witness' testimony either relates to matters beyond the knowledge or experience possessed by lay persons or dispels a misconception common among lay persons; (B) The witness is qualified as an expert by specialized knowledge, skill, experience, training, or education regarding the subject matter of the testimony; (C) The witness' testimony is based on reliable, scientific, technical, or other specialized information. To the extent that the testimony reports the result of a procedure, test, or experiment, the testimony is reliable only if all of the following apply: (1) The theory upon which the procedure, test, or experiment is based is objectively verifiable or is validly derived from widely accepted knowledge, facts, or principles; (2) The design of the procedure, test, or experiment reliably implements the theory; (3) The particular procedure, test, or experiment was conducted in a way that will yield an accurate result."

{¶ 25} Here the issue is whether appellant's experts' testimony "is based on reliable scientific, technical, or other specialized information." (Emphasis added.) Evid.R. 702(C). In general terms, the reliability of an expert's opinion depends upon (1) the validity of the underlying theory, (2) the validity of the technique used to apply that theory, and (3) the proper application of the technique on a particular occasion. InDaubert the United States Supreme Court identified a series of specific reliability inquiries that apply in the context of the "hard" or quantitative sciences. These factors include (1) whether a theory or technique can be and has been tested, (2) known error rates, (3) peer review and publication, and (4) general acceptance in the field.

{¶ 26} The court made it clear in Kumho Tire Co. that the reliability analysis adopted in Daubert for scientific experts also applied to experts with other types of technical or specialized knowledge. But it is critical to realize that the analysis of reliability is flexible and its indicators may vary from discipline to discipline. Daubert, 509 U.S. at 593,113 S. Ct. 2786, 125 L. Ed. 2d 469; see, also, Moore v. Ashland Chem.,Inc. (C.A.5 1997), 126 F.3d 679, at 686-688. Thus, the court should proceed in a two-step process that first identifies the indicators of reliability that are appropriate for the discipline involved and then applies them. In this instance, we will focus primarily on general acceptance, testing, known error rates, and "fit." For our purposes we assume without deciding that the studies cited by appellant's experts meet the peer-review criterion.

{¶ 27} In order to determine reliability, a court must assess whether the reasoning or methodology underlying the testimony is valid. Miller, 80 Ohio St.3d at 611, 687 N.E.2d 735, citingDaubert, 509 U.S. at 592-593, 113 S. Ct. 2786, 125 L. Ed. 2d 469. Thus, an expert may not base an opinion upon "subjective belief or unsupported speculation." Daubert, 509 U.S. at 590,113 S. Ct. 2786, 125 L. Ed. 2d 469; see, also, State v. Hurst (Mar. 7, 2000), Franklin App. No. 98AP-1549, 2000 WL 249110. Instead, the expert's opinion must be based on methods and procedures that meet the level of intellectual rigor demanded by the relevant discipline. See In re Paoli (C.A.3, 1994), 35 F.3d 717, 742, citing Daubert, 509 U.S. at 590, 113 S. Ct. 2786,125 L. Ed. 2d 469. The "[p]roposed testimony must be supported by appropriate validation — i.e., ``good grounds,' based on what is known."Daubert, 509 U.S. at 590, 113 S. Ct. 2786, 125 L. Ed. 2d 469. And "where such testimony's factual basis, data, principles, methods, or their application are called sufficiently into question, * * * the trial judge must determine whether the testimony has a ``reliable basis in the knowledge and experience of [the relevant] discipline.'" Kumho, 526 U.S. 137, 119 S. Ct. 1167,143 L. Ed. 2d 238, quoting Daubert, 509 U.S. at 592, 113 S. Ct. 2786,125 L. Ed. 2d 469; see, also, Daniel J. Capra, The Daubert Puzzle (1998) 32 Ga.L.Rev. 699, 705 ("In deciding the question of admissibility, trial judges must consider the degree to which the accuracy of scientific information has been established. The less certain the scientific community is about information, the less willing courts should be to receive it"). In other words, "[s]cientific evidence and expert testimony must have a traceable, analytical basis in objective fact before it may be considered on summary judgment." Bragdon v. Abbott (1998),524 U.S. 624, 653, 118 S. Ct. 2196, 141 L. Ed. 2d 540; see, also, Gen.Elec. Co. v. Joiner (1997), 522 U.S. 136, 144-146,118 S. Ct. 512, 139 L. Ed. 2d 508. However, "[t]he grounds for the expert's opinion merely have to be good[;] they do not have to be perfect." Paoli, 35 F.3d at 744.

{¶ 28} A court resolving a reliability question should consider the "principles and methods" the expert used "in reaching his or her conclusions, rather than trying to determine whether the conclusions themselves are correct or credible." Nemeth,82 Ohio St.3d at 210, 694 N.E.2d 1332; see, also, Miller,80 Ohio St. 3d 607, 687 N.E.2d 735, paragraph one of the syllabus. As theDaubert court stated, in assessing reliability, "[t]he focus * * * must [generally] be * * * on principles and methodology, not on the conclusions that they generate." Daubert,509 U.S. at 595, 113 S. Ct. 2786, 125 L. Ed. 2d 469.

{¶ 29} A trial court may not, therefore, exclude expert testimony simply because it disagrees with the expert's conclusions. Instead, if the expert followed methods and principles deemed valid by the discipline to reach his opinion, the court should allow the testimony. See Paoli,35 F.3d at 742 ("an expert's testimony is admissible so long as the process or technique the expert used in formulating the opinion is reliable").³ The traditional adversary process is then capable of weeding out those shaky opinions. SeeDaubert, 509 U.S. at 596, 113 S. Ct. 2786, 125 L. Ed. 2d 469.

{¶ 30} In addition to being scientifically or technically reliable, expert testimony also must "fit" the case at hand; that is, the testimony must be "``relevant to the task at hand' in that it logically advances a material aspect of the proposing party's case." Daubert, 509 U.S. at 597, 113 S. Ct. 2786,125 L. Ed. 2d 469; see, also, Hall v. Baxter Healthcare Corp.,947 F.Supp. at 1396; Moore v. Ashland Chem. Inc. (C.A.5, 1998), 151 F.3d 269,275 ("Rule 104(a) requires the judge to conduct preliminary fact-finding and to make a ``preliminary assessment of whether the reasoning or methodology underlying the testimony * * * properly can be applied to the facts in issue,'" quoting Daubert,509 U.S. at 592-593, 113 S. Ct. 2786, 125 L. Ed. 2d 469). Thus, "admissibility depends in part on ``the proffered connection between the scientific research or test result to be presented and particular disputed factual issues in the case.' Downing,753 F.2d at 1237." Paoli, 35 F.3d at 743.

{¶ 31} In Cavallo v. Star Ent. (E.D.Va. 1995),892 F. Supp. 756, 761, the court gave this explanation of the requirement of fit: "The distinction between ``scientific validity' and ``fit' is not always clear and the two inquiries may overlap in a particular case. For instance, there may be times where an expert relies on published literature and widely accepted, tested theories in forming her opinion, and her ultimate conclusion is clearly relevant to an issue in the case. Yet, if those published theories and studies purport to prove XYZ, and from them, the expert concludes ABC, it may be that the expert's reasoning process itself is not scientifically valid. Put another way, there may be a lack of ``fit' between the tested theories relied upon and the ultimate conclusion reached." Accordingly, courts have an obligation to ensure that there is a valid link between the sources or studies the expert consulted and the conclusion the expert reached. Cavallo, 892 F.Supp. at 762. "[A] determination regarding the scientific validity of a particular theory requires not only an examination of the trustworthiness of the tested principles on which the expert opinion rests, but also an analysis of the reliability of an expert's application of the tested princip[les] to the particular set of facts at issue." (Emphasis sic.) Cavallo, 892 F.Supp. at 762-763.

{¶ 32} Thus, an expert's opinion would not fit if sources relied upon by the expert did not actually support the expert's opinion. As the Paoli court more specifically explained: "[A]nimal studies may be methodologically acceptable to show that chemical X increased 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.' Id. [509 U.S.] at 591 [113 S. Ct. 2786,125 L. Ed. 2d 469]. 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.' Id. 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,35 F.3d at 743.

{¶ 33} In cases alleging that chemical exposure caused a plaintiff to contract cancer, the question whether the expert's testimony regarding general causation is reliable, or fits, looms large. This is so because in most cases, the only thing that scientists know for certain about the causes of cancer is the limited nature of their knowledge. See Michael D. Green, Expert Witnesses and Sufficiency of Evidence in Toxic Substances Litigation: The Legacy of Agent Orange and Bendectin Litigation (1992), 86 N.W.U.L.Rev. 643, 644, quoting Environmental DefenseFund v. Environmental Protection Agency (C.A.D.C. 1978),598 F.2d 62, 89. Ascertaining the reliability and fit of such testimony can be difficult because of the very fact that science has demonstrated so little as to the causes of cancer (with certain rare exceptions, of course, such as cigarette smoking and lung cancer). As Green writes: "Ideally, to demonstrate that a given agent was a necessary link in the causal chain that led to an individual's disease, one would trace each of the steps in the biology of the development of the disease, including the essential role played by the agent. To state this ideal is to recognize its futility, at least given the current state of scientific affairs. * * * Because the biological mechanisms of most diseases are understood marginally at best, other devices are necessary to attempt causal attributions. In the absence of direct evidence, scientific methods that permit causal inference — the essence of science is to permit generalizations from observed phenomena — are employed." (Footnotes omitted.) Id. at 644-645.

{¶ 34} Nonetheless, in attempting to show that a chemical substance can cause a particular medical condition (general causation), the expert ideally proceeds in "a stepwise fashion." Federal Judicial Center, Reference Manual on Scientific Evidence (2000) 468. "In the first step the physician must establish the characteristics of the medical condition. Second, he or she carefully defines the nature and amount of the environmental exposure. The third step is to demonstrate that the medical and scientific literature provides evidence that in some circumstances the exposure under consideration can cause the outcome under consideration. This step is synonymous with establishment of general causation. As part of this step, the clinician attempts to establish the relationship between dose and response, including whether thresholds exist, ultimately defining the clinical toxicology of the exposure. The fourth step is to apply this general knowledge to the specific circumstances of the case at hand, incorporating the specifics of exposure, mitigating or exacerbating influences, individual susceptibilities, competing or synergistic causes, and any other relevant data." (Footnotes omitted.) Id. at 468-470.

{¶ 35} Because of the limitations of hard scientific knowledge, especially about the causes of cancer, experts commonly extrapolate from existing data. Extrapolation is a valid expert technique when properly performed and explained. "But nothing in either Daubert or the Federal Rules of Evidence requires a district court to admit opinion evidence that is connected to existing data only by the ipse dixit of the expert. A court may conclude that there is simply too great an analytical gap between the data and the opinion proffered." Gen. Elec. Co. v. Joiner (1997), 522 U.S. 136, 146, 118 S. Ct. 512, 139 L. Ed. 2d 508.Daubert and its progeny require a court to examine the rationale and methods behind the extrapolation to determine whether it is scientifically valid or whether the analytical gap is too wide. See Hall, 947 F.Supp. at 1400 ("``Daubert * * * 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'"), quoting David E. Bernstein, The Admissibility of Scientific Evidence After Daubert v. MerrellDow Pharmaceuticals, Inc. (1999), 15 Cardozo L.Rev. 2139, 2165-2166.

{¶ 36} Several types of improper extrapolation commonly appear, "including extrapolating (1) from a structure analysis for similar compounds, (2) that a substance that causes one type of harm also causes a different type of harm, (3) upon the basis of methodology that is transposed from one area of inquiry to a completely different one, (4) from epidemiological studies with different exposures, and (5) when data regarding the plaintiff's exposure is unknown." (Footnotes omitted.) Judge Harvey Brown, Eight Gates for Expert Witnesses (1991), 36 Hous.L.Rev. 743 at 811, citing Capra, 32 Ga.L.Rev. 699, supra.

III. The Experts' Opinions⁴ {¶ 37} In this case there is no direct scientific evidence that any particular chemical or group of chemicals to which Valentine was exposed caused his glioblastoma multiforme. The plaintiff's experts agree that the only scientifically proven cause of brain tumors is ionizing radiation, a factor that is not applicable in this case. Thus, in reaching their opinions, appellant's experts have extrapolated from other scientific data. A. Epidemiological Studies {¶ 38} Dr. Newton, Dr. Miner, and Mr. Brusk have extrapolated from epidemiological studies, which Green characterizes as follows: "The most desirable evidence is epidemiologic, because it can best be generalized to support inferences about the effect of an agent in causing disease in humans. Epidemiology studies the causes of disease in humans as inferred from observation of humans. Epidemiologic studies are conducted on groups of individuals, i.e., a sample, to isolate and determine the effect of a given agent or factor on the incidence of disease in the population as a whole. These studies entail a comparison of the incidence of disease in a population exposed to the agent being examined with the incidence of disease in an otherwise similar, but unexposed, population, i.e., the control. When epidemiologists study agents that are thought of as toxins — cigarettes, asbestos, drugs, and chemicals — the results of their study may be helpful to the legal system in assessing causation. Because epidemiology is conducted on human populations, it has greater generalizability to those outside the population studied than other toxicological methods, such as animal studies." Green, supra, 86 N.W.U.L.Rev. at 646.

{¶ 39} While epidemiological studies can be "powerful evidence of causation," their absence "is not fatal to a plaintiff's case." Rider v. Sandoz Pharmaceuticals Corp. (C.A.11, 2002),295 F.3d 1194, 1198. "Epidemiological studies are merely a tool, not a panacea, for finding toxic causation," Green, supra, 86 N.W.U.L.Rev. at 699, and "[a]t best, epidemiology assesses the likelihood that the agent caused a specific individual disease," id. at 647.

{¶ 40} However, extrapolating from epidemiological studies may not always be proper. See, generally, Joiner, 522 U.S. 136,118 S. Ct. 512, 139 L. Ed. 2d 508.⁵ "The epidemiological studies must correspond closely enough with the plaintiff's exposure and injury, and they must find a statistically significant connection between the particular substance and the injury alleged by the plaintiff." Capra, 32 Ga.L.Rev. 719; see, also, Christophersen v. Allied-Signal Corp. (C.A.5, 1991), 939 F.2d 1106, 1115-1116 (stating that experts may not rely on studies that do not address the types of diseases at issue); Allen v. Pennsylvania Eng. Corp. (C.A.5, 1996),102 F.3d 194, 197 (studies suggesting that chemical exposure causes lymphatic and hematopoietic cancer are not probative to cause of brain cancer); Schmaltz v. Norfolk W. Ry. Co. (N.D.Ill. 1995), 878 F. Supp. 1119, 1122.

{¶ 41} The existence of an epidemiological study alone does not make expert testimony fit a plaintiff's case. "[A] claimant must do more than simply rely on epidemiological studies that show a substantially elevated risk. A claimant must show that he or she is similar to those in the studies. This would include proof that the injured person was exposed to the same substance, that the exposure or dose levels were comparable to or greater than those in the studies, that the exposure occurred before the onset of injury, and that the timing of the onset of injury was consistent with that experienced by those in the study." Merrell DowPharmaceuticals, Inc. v. Havner (1997), 953 S.W.2d 706, 720; see, also, Capra, 32 Ga.L.Rev. at 726 ("a valid study finding a connection between a substance and an injury will fail the ``fit' requirement if the plaintiff's exposure to the substance is materially different from the exposures considered in the study"); Cavallo, 892 F.Supp. at 766 ("While Rule 702 does not necessarily mandate that the expert find a study linking the exact chemical at the exact exposure levels with the exact illnesses at issue, it does require that the expert demonstrate a scientifically valid basis for projecting the findings of a study identifying a different chemical-illness relationship to the proffered causal theory").

{¶ 42} In reaching their causation opinions here, appellant's experts relied on epidemiological studies "suggestive" of a link between various chemical exposures and glioblastoma multiforme. However, none of the epidemiological studies concerned the same industry in which Valentine worked, and, more important, none of the studies could identify a chemical or group of chemicals that caused the brain tumor excess. Thus, extrapolation produced unreliable results because none of the epidemiological studies the appellant's experts relied upon could conclusively identify the cause of the brain tumor excess. See Bragdon v. Abbott (1998), 524 U.S. 624, 653, 118 S. Ct. 2196, 141 L. Ed. 2d 540 ("The study on which petitioner relied was inconclusive, however, determining only that ``[f]urther work is required to determine whether such a risk exists,'" quoting Johnson Robinson, Human Immunodeficiency Virus-1 (HIV-1) in the Vapors of Surgical Power Instruments (1991), 33 J. of Med. Virology 47); see, also, Allenv. Pennsylvania Eng. Corp. (C.A.5, 1996), 102 F.3d 194, 197 (epidemiological studies that "suggest" a link between chemical exposure and brain cancer are not statistically significant so as to lend credence to expert causation opinion). Because appellant's experts relied on studies that do not support the experts' conclusions, those opinions are not scientifically reliable. These studies fall far short of proving their hypothesis. They are a starting point for further research, not scientific proof of causation. To the extent that the experts based their opinions upon and extrapolated from the epidemiological studies, the trial court did not abuse its discretion in finding them inadmissible.

B. Animal Studies {¶ 43} Appellant's experts also stated that they relied upon animal studies. "While it is quite true that animal data can be important indicia of human health effects, direct transference from one to the other may or may not be possible, depending, in part, on the type of effect and the dosage used to achieve that effect." Wiley, supra fn. 1, Section 1.04[C], at 21. "[T]he more closely those specific organ system effects are known to mimic effects in people and the closer the dosage creating the effect in the animal is to the human dosage, the better the argument for transferability." Id., Section 1.04[D], at 21-22.

{¶ 44} In Joiner, the court considered the reliability of an expert's opinion when the expert relied on animal studies to reach a causation opinion. The court noted: "The studies involved infant mice that had developed cancer after being exposed to PCB's. The infant mice in the studies had had massive doses of PCB's injected directly into their peritoneums or stomachs. Joiner was an adult human being whose alleged exposure to PCB's was far less than the exposure in the animal studies. The PCB's were injected into the mice in a highly concentrated form. The fluid with which Joiner had come into contact generally had a much smaller PCB concentration of between 0-to-500 parts per million. The cancer that these mice developed was alveologenic adenomas; Joiner had developed small-cell carcinomas. No study demonstrated that adult mice developed cancer after being exposed to PCB's. One of the experts admitted that no study had demonstrated that PCB's lead to cancer in any other species."Joiner, 522 U.S. at 144, 118 S. Ct. 512, 139 L. Ed. 2d 508.

{¶ 45} The Joiner court concluded that "[t]he studies were so dissimilar to the facts presented in this litigation that it was not an abuse of discretion for the District Court to have rejected the experts' reliance on them." Id.

{¶ 46} Here, appellant's experts have not sufficiently explained what enables them to extrapolate from the animal studies to humans. Moreover, the chemical exposures in the animal studies did not cause brain tumors to develop across species. See Allen, 102 F.3d at 197 (finding expert's reliance on animal studies in forming causation opinion unreliable when chemical exposure did not consistently result in brain tumors across species). Without further explanation of the logic and reasoning behind extrapolating from the animal studies to humans, the trial court was well within its discretion to exclude appellant's experts' testimony.

C. Experience {¶ 47} Dr. Miner stated that he reached his opinion based upon his many years of treating patients with brain tumors and upon his experience in the Houston, Texas area, where several petroleum workers contracted brain tumors. Case reports in and of themselves are not invalid. However, they best describe associations, not causation. The mere coincidence of exposure and the appearance of a disease is never sufficient to prove causation in an individual instance. Susan R. Poulter, Science and Toxic Torts: Is There a Rational Solution to the Problem of Causation? (1992), 7 High Tech.L.J. 189 at 216. Even clustering of a disease can occur by random chance or other causes. Id. In other words, "[t]hey reflect only reported data, not scientific methodology." Rider, 295 F.3d at 1199; see, also, Haggerty v.Upjohn Co. (S.D.Fla. 1996), 950 F. Supp. 1160, 1165 ("while case reports may provide anecdotal support, they are no substitute for a scientifically designed and conducted inquiry"); Casey v. OhioMed. Prods. (N.D.Cal. 1995), 877 F. Supp. 1380, 1385 ("case reports are not reliable scientific evidence of causation, because they simply described reported phenomena without comparison to the rate at which the phenomena occur in the general population or in a defined control group; do not isolate and exclude potentially alternative causes; and do not investigate or explain the mechanism of causation"). Importantly, there is no means of determining the rate of error involved in anecdotal reports. In short, these opinions cannot be tested. Moreover, experience alone does not make an otherwise unfounded conclusion scientifically reliable. See, generally, David L. Faigman et al., How Good Is Good Enough? Expert Evidence UnderDaubert and Kumho (2000), 50 Case W.Res.L.Rev. 645, 657.

{¶ 48} Therefore, the trial court did not abuse its discretion in finding that Dr. Miner's reliance on his experience, including his observation of workers in the petroleum industry, does not sufficiently demonstrate the reliability of his opinion.

D. Governmental Regulatory Policy {¶ 49} In reaching his causation opinion, Brusk also relied upon various regulatory agencies' classification of some of the chemicals as carcinogenic. That a regulatory agency chooses to classify a chemical as carcinogenic does not give credence to an expert's opinion that the chemical caused a plaintiff's specific type of cancer. Two problems inhere in inferring causation from such a classification. First, the regulatory body's classification of the chemical does not determine admissibility of expert testimony on the subject. Second, to classify a chemical as carcinogenic is to say that it causes cancer. What type of cancer is an unresolved question. It is generally well understood that carcinogens cause specific types of cancer. Thus, to state that a chemical is carcinogenic answers only half of the question. SeeAllen, 102 F.3d at 196 ("the fact that [ethylene oxide] has been classified as a carcinogen by agencies responsible for public health regulations is not probative of the question whether [the plaintiff's] brain cancer was caused by [this] exposure").

{¶ 50} Moreover, "substances are regulated because of what they might do at given levels, not because of what they will do." Wiley, supra fn. 1, Section 1.07, at 33. The fact of regulation does not imply scientific certainty. It may suggest a decision to err on the side of safety as a matter of regulatory policy rather than the existence of scientific fact or knowledge. See id., Section 1.07, at 34. "A regulatory agency such as the FDA may choose to err on the side of caution. Courts, however, are required by the Daubert trilogy to engage in objective review of evidence to determine whether it has sufficient scientific basis to be considered reliable." Rider, 295 F.3d at 1201. The mere fact that substances to which Valentine was exposed may be listed as carcinogenic does not provide reliable evidence that they are capable of causing brain cancer, generally or specifically, in Valentine's case. We have no reason to conclude that the trial court erred on this basis.

E. Differential Diagnosis {¶ 51} Appellant's medical experts have also asserted that they reached their conclusions of specific causation after conducting a differential diagnosis of Valentine.

{¶ 52} Differential diagnosis⁶ can be a valid expert technique. See Hardyman v. Norfolk W. Ry. Co. (C.A.6, 2001),243 F.3d 255, 260 (stating that differential diagnosis is one appropriate method for determining causation in an individual); Westberry v. Gislaved Gummi AB (C.A.4, 1999), 178 F.3d 257, 262 (stating that differential diagnosis is a standard scientific technique); Cutlip v. NorfolkS. Corp., Lucas App. No. L-02-1051, 2003-Ohio-1862, 2003 WL 1861015. "Differential diagnosis" is defined as "``[t]he method by which a physician determines what disease process caused a patient's symptoms. The physician considers all relevant potential causes of the symptoms and then eliminates alternative causes based on a physical examination, clinical tests, and a thorough case history.'" Hardyman, 243 F.3d at 260, quoting Federal Judicial Center, Reference Manual on Scientific Evidence (1994) 214. "A reliable differential diagnosis typically, though not invariably, is performed after ``physical examination, the taking of medical histories, and the review of clinical tests, including laboratory tests,' and generally is accomplished by determining the possible causes for the patient's symptoms and then eliminating each of these potential causes until reaching one that cannot be ruled out or determining which of those that cannot be excluded is the most likely." Westberry,178 F.3d at 262.

{¶ 53} However, differential diagnosis alone does not always establish proximate cause, particularly when general causation evidence is lacking. "The process of differential diagnosis is undoubtedly important to the question of ``specific causation.'"Cavallo, 892 F.Supp. at 771. But a valid differential diagnosis presupposes that general causation has been established, i.e., that agent X is capable of causing brain tumors in humans generally. See Cavallo, 892 F.Supp. at 771 ("a fundamental assumption underlying [differential diagnosis] is that the final, suspected ``cause' remaining * * * must actually be capable of causing the injury"); see, also, Hollander v. SandozPharmaceuticals Corp. (C.A.10, 2002), 289 F.3d 1193, 1210 ("In many of the decisions in which a differential diagnosis has been deemed reliable, the party relying on the diagnosis has offered independently reliable evidence that the allegedly dangerous drug or substance had harmful effects"); Hall, 947 F.Supp. at 1413, citing Cavallo. Thus, "the expert must ``rule in' the suspected cause as well as ``rule out' other possible causes." Cavallo,892 F.Supp. at 771. Here, we have concluded there is no other evidence to "rule in" Valentine's exposure as a general causation agent. Moreover, "If other possible causes of an injury cannot be ruled out, or at least the probability of their combination to causation minimized, then the ``more likely than not' threshold for proving causation may not be met.'" Cavallo,892 F.Supp. at 771. In other words, the technique is valid where the causes of the disease are known. Differential diagnosis presupposes the causes are known and then proceeds to eliminate them based upon the premise that the absence of other risk factors increases the likelihood that the patient's disease was caused by exposure to the toxic substance. Where the other causes are unknown, there is nothing to eliminate and thus no increase in likelihood of causation by the toxic agent. See Expert Witnessing: Explaining and Understanding Science, Carl Meyer, CRC Press (1999), Chapter 12, Medical and Scientific Evidence of Causation.

{¶ 54} For example, in Cavallo, the plaintiff's expert used differential diagnosis to opine that the plaintiff's exposure to jet fuel caused her respiratory problems. However, the plaintiff presented no reliable evidence that jet fuel fumes could, in fact, cause such respiratory problems. See, also, Raynor v.Merrell Pharmaceuticals, Inc. (C.A.D.C. 1997), 104 F.3d 1371 (rejecting differential diagnosis when general causation had not been established).

{¶ 55} Compare Cavallo with Westberry, where the court found the expert's differential diagnosis reliable to prove causation when general causation already had been established. The court noted that "it was undisputed that inhalation of high levels of talc irritates mucous membranes." Westberry,178 F.3d at 264; see, also, Mattis v. Carlon Elec. Products (C.A.8, 2002), 295 F.3d 856 (accepting differential diagnosis for causation when evidence also existed regarding general causation).

{¶ 56} Here, the cause of brain tumors is largely unknown (except for ionizing radiation). To state that nothing else caused the brain tumor is contrary to the medical and scientific fact that the cause of brain tumors is unknown. At this point, medical science does not enable physicians and other scientists to pinpoint a cause of brain cancer (except for ionizing radiation). Both Dr. Miner and Dr. Newton readily acknowledged the current status of medical and scientific knowledge in their depositions. Thus, under the circumstances of this case the trial court did not abuse its discretion in concluding that differential diagnosis is not a reliable technique for identifying causation.

IV. Conclusion {¶ 57} Consequently, we reluctantly conclude that the trial court did not abuse its discretion by finding appellant's experts' testimony to be unreliable and inadmissible. There is no relevant direct scientific or technical evidence that identifies the agents of general causation for brain tumors in humans. In forming their opinions, the experts have improperly interpreted epidemiological studies, animal studies, and cancer regulatory policy. Causation opinions based upon the differential diagnosis are not reliable in this case because that technique requires both ruling in the suspected agent and ruling out the other causes of the disease; the present state of scientific knowledge on the cause of brain cancer precludes reliability in this context. To the extent appellant relies on Brusk's testimony to establish causation, his testimony is inadmissible for the same reasons as Dr. Miner's and Dr. Newton's testimony. Without her experts' testimony, appellant possesses no evidence of a cause-and-effect relationship between Valentine's brain cancer and his workplace. The mere fact that no other evidence is available does not warrant the admission of clearly unreliable evidence. Thus, we then are compelled to agree with the trial court's decision entering summary judgment in PPG's favor.

{¶ 58} Based upon the foregoing reasons, we overrule appellant's first through fourth assignments of error.

V. {¶ 59} In her fifth assignment of error, appellant argues that the trial court abused its discretion when ruling on a wide variety of discovery matters, which are summarized in Appendix Two.

{¶ 60} In this case, any error that the trial court may have committed in ruling on discovery matters is harmless. Civ.R. 61 provides: "No error in either the admission or the exclusion of evidence and no error or defect in any ruling or order or in anything done or omitted by the court or by any of the parties is ground for granting a new trial or for setting aside a verdict or for vacating, modifying or otherwise disturbing a judgment or order, unless refusal to take such action appears to the court inconsistent with substantial justice. The court at every stage of the proceeding must disregard any error or defect in the proceeding which does not affect the substantial rights of the parties." See, also, Siuda v. Howard, Hamilton App. Nos. C-000656 and C-000687, 2002-Ohio-2292, 2002 WL 946188, at ¶ 21, citing Meyers v. Hot Bagels Factory, Inc. (1999),131 Ohio App. 3d 82, 100-101, 721 N.E.2d 1068 ("harmless error is an error that does not affect the substantial rights of the parties").

{¶ 61} "``In determining whether a substantial right of a party has been affected, the reviewing court must decide whether the trier of fact would have reached the same decision, had the error not occurred.'" Prakash v. Copley Twp., Summit App. No. 21057, 2003-Ohio-642, 2003 WL 294365, quoting Moore v. Univ. of Akron (Aug. 1, 2001), Summit App. No. 20320, 2001 WL 866274. "``Generally, in order to find that substantial justice has been done to an appellant so as to prevent reversal of a judgment for errors occurring at the trial, the reviewing court must not only weigh the prejudicial effect of those errors but also determine that, if those errors had not occurred, the jury or other trier of the facts would probably have made the same decision.'Hallworth v. Republic Steel Corp. (1950), 153 Ohio St. 349 [41 Ohio Op. 341], 91 N.E.2d 690, paragraph three of the syllabus." Cappara v. Schibley (1999),85 Ohio St. 3d 403, 408, 709 N.E.2d 117.

{¶ 62} In this case, had the trial court ruled in appellant's favor regarding the various discovery requests, none of the requested material would have helped appellant establish the reliability of her experts' testimony. Therefore, no prejudice resulted from the court's discovery rulings.

{¶ 63} Accordingly, we overrule appellant's fifth assignment of error and affirm the trial court's judgment.

Judgment affirmed.

PETER B. ABELE, J., concurs.

¹ The plaintiff must show that he was exposed to the toxic substance and that the level of exposure was sufficient to induce the complained-of medical condition (commonly called a "dose-response relationship"). See, generally, Wiley, Expert Witness Update: New Developments in Personal Injury Litigation (2000), Section 1.04, at 18-19, and Section 1.05[C], at 28 ("the dose makes the poison"). Here, PPG asserts that appellant lacks exposure evidence. However, we assume for the sake of argument that appellant has established exposure and a dose-response relationship.

² We have rejected the Olinger court's position on causation based upon the Supreme Court's pronouncement in Murphyv. Carrollton Mfg. Co., supra. However, Olinger's conclusion that strict application of general and specific causation is not warranted in worker's compensation cases arguably seems reasonable in light of the remedial purpose of the statutes. We encourage certification of the conflict on this issue to the Supreme Court for final resolution.

³ Because of the lack of Ohio cases addressing the precise issue here (i.e., the admissibility of expert testimony that a toxic substance proximately caused the plaintiff's condition), we look to the federal courts for guidance.

⁴ See Appendix One for a summary of the evidence that the parties submitted.

⁵ See Appendix Three for a summary of the Joiner court's analysis of improper extrapolation from four studies.

⁶ Some commentators have noted that the legal system's use of "differential diagnosis" to mean the process of eliminating causes is improper. Instead, medical professionals use the term to describe the process of identifying the disease the patient is suffering from. See Reference Manual on Scientific Evidence at 443-444 (footnotes omitted): "[C]ourts have come to use certain medical terms, such as differential diagnosis and differential etiology in ways that differ from their common usage in the medical profession. For example, although environmental and occupational health physicians may use the term ``differential diagnosis' to include the process of determining whether an environmental or occupational exposure caused the patient's disease, most physicians use the term to describe the process of determining which of several diseases is causing a patient's symptoms. Expert witnesses and courts, however, frequently use the term ``differential diagnosis' to describe the process by which causes of the patient's condition are identified, particularly causes external to the patient. Additionally, courts sometimes characterize causal reasoning as ``differential etiology,' a term not used in medical practice, but one that more closely suggests the determination of a cause." The reference manual suggests that a more appropriate term would be "external causation."