OPINION AND ORDER
SCHEINDLIN, District Judge.
I. INTRODUCTION
In November 1988, a pipeline transporting petroleum products from Texas to Illinois released thousands of gallons of gasoline onto a property known as Danhausen Farm in Limestone Township, Kankakee County, Illinois.1 “A pool of gasoline about 450 feet by 50 feet appeared among fields of corn and soybeans,” according to the Illinois Environmental Protection Agency.2
The gasoline contained a number of additives including MTBE (methyl tertiary butyl ether), various byproducts, and BTEX (benzene, toluene, ethylbenzene, and xylenes).3 An information packet published by the Illinois Environmental Protection Agency in 2002 explains:
The geology within the release area consists of a six to eight foot layer of loess and Silurian age Racine dolomite. The upper 15 feet of the dolomite in this area is highly fractured permitting contaminants to seep into the bedrock aquifer that provides drinking water for many homes in the area. The groundwater in this area is moving towards the Kankakee River.4
Thirteen years after the release, residents and property owners from Limestone Township filed this action against Shell Oil Company and certain companies involved with the [438]*438pipeline (“Companies”).5 The individual plaintiffs include: (1) Edith Quick, (2) Lisa and Carl Kibbons and their son Evan, (3) Edith and Gregory Buckley and their daughter Ellen, (4) Lisa and Jeffrey Quick, (5) Cathy and Charles Quick (Jr.), (6) John Panozzo, the guardian of Marguerite Panozzo, (7) Angela and Christopher Burge, and (8) Kenneth Clark.6 These individual plaintiffs allege that the Companies are hable for the torts of (1) trespass, (2) private nuisance, (3) negligence, and (4) defective product design of MTBE and its byproducts.7 In addition, the individual plaintiffs sued the company that tested water samples in the area in the years after the spill, Parsons Engineering Science, Inc., as well as two of its employees (the “Parson Defendants”).8
Two of these individual plaintiffs, John Panozzo and Lisa Kibbons (“Plaintiffs”), now move under Rule 23 of the Federal Rules of Civil Procedure to represent three subclasses of people who were harmed by the alleged torts committed by the Companies and the Parson Defendants (collectively referred to as “Defendants”). In particular, Plaintiffs seek certification of three subclasses to include people who were harmed after January 1,1988, because:
(1) their real property was contaminated by gasoline from the pipeline release resulting in the loss of market value or quiet enjoyment of the property (subclass one);
(2) their wells and other sources of water were contaminated by gasoline from the pipeline release resulting in expenses associated with procuring uncontaminated water including the cost of connecting to a public or commercial source of uncontaminated water (subclass two);
(3) they were exposed to gasoline contamination from the pipeline resulting in personal injury, or an increased risk of personal injury, including cancer (subclass three).9
It is well-established that a court has the inherent power and discretion “to redefine and modify a class in a way which allows maintenance of an action as a class action.”10 Plaintiffs’ proposed three subclasses warranted modification because they are too broad. In particular, the Companies and the Parson Defendants cannot be part of the same class definition because the question of whether the Companies are liable for their alleged torts arising out of the gasoline spill (trespass, private nuisance, negligence, and [439]*439strict liability) is different than the question of whether the Parson Defendants are liable for the tort of negligence in testing water at various people’s property after the spill. Because the only way to maintain the action as a class action is to modify the proposed class, the Court will redefine the classes so that the Companies and the Parson Defendants are considered separately.
II. THE LAW OF THE TRANSFEROR COURT APPLIES TO CLASS CERTIFICATION IN MULTI-DISTRICT LITIGATION
A threshold question that must be addressed is whether the law of the transfer- or circuit should control when applying Rule 23 (i.e. Seventh Circuit) or, in the alternative, the law of the transferee circuit (i.e., Second Circuit).11 As explained below, the law of the transferor circuit applies to this motion for class certification under Rule 23.
This case was transferred to this Court pursuant to 28 U.S.C. § 1407, which states in pertinent part: “When civil actions involving one or more common questions of fact are pending in different districts, such actions may be transferred to any district for coordinated or consolidated pretrial proceedings.” 12 “The plain language of the statute does not explicitly resolve the issue of which circuit’s law is binding, but it is important that section 1407 only allows cases to be transferred on the condition that such coordination ‘will promote the just and efficient conduct of such actions.’ ”13
In the context of pre-trial issues such as motions to dismiss or discovery disputes, section 1407 requires the application of the law of the transferee circuit where the motions are being considered.14 For example, courts have held that the law of the transferee circuit controls pretrial issues such as whether the court has subject matter or personal jurisdiction over the action, or whether the cases should be remanded to state court because the cases were not properly removed.15 Likewise, the law of the transferee circuit controls discovery issues such as whether to compel a deposition or documents pursuant to a subpoena.16
The law of the transferee circuit applies in each of these situations because the “objective of transfer is to eliminate duplication in discovery, avoid conflicting rulings and schedules, reduce litigation costs, and save the time and effort of the parties, the attorneys, the witnesses, and the courts.”17 Section 1407 is aimed at eliminating “delay, confusion, conflict, inordinate expense and inefficiency” during the pretrial period.18 In other words, it promotes “just and efficient” resolution of the proceedings to apply the law of the transferee circuit to pretrial issues.19
However, whether to certify an action on behalf of a class under Rule 23 is not merely a pretrial issue. In Coopers & Lybrand v. Livesay,20 the Supreme Court first observed that “the class determination generally involves considerations that are enmeshed in [440]*440the factual and legal issues comprising the plaintiffs cause of action.”21 The Court repeated this observation four years later in General Telephone Company of Southwest v. Falcon.22
More importantly, in Amchem Products, Inc. v. Windsor23 the Supreme Court held that when certifying a class action under Rule 23, the requirements of Rule 23(b)(3) must always be satisfied for purposes of the trial regardless of whether a jury will consider the case because the parties have settled. In Amchem, the Supreme Court held that, with one exception, a proposed settlement was irrelevant to determining whether a class should be certified under Rules 23(a) and 23(b)(3). “Settlement is relevant to a class certification” only because a district court “need not inquire whether the case, if tried, would present intractable management problems ... for the proposal is that there be no trial.”24
At the same time, the Supreme Court emphasized that “other specifications of the Rule—those designed to protect absentees by blocking unwarranted or overbroad class definitions—demand undiluted, even heightened, attention in the settlement context.”25 Thus, courts must determine whether Rule 23 is satisfied for purposes of trial before granting certification.26
Not only are class certification requirements inherently enmeshed with considerations of the trial, but under Lexecon Inc. v. Milberg Weiss Bershad Hynes & Lerach27 the authority of the transferee court in multidistrict proceedings ends once the pretrial proceedings are completed.28 Lexecon requires this Court to return each case to its original district for trial after the pretrial phase has been completed. It would be neither just nor efficient to apply the law of this Circuit in considering class certification, and then force the transferor court to try a class action that it might never have certified.
Finally, Plaintiffs originally filed their state tort claims in Illinois state court.29 Defendants removed the action to federal court under the federal officer removal statute and the case was then transferred to this Court by the Judicial Panel on Multidistrict Litigation.30 In a similar context, the Manual for Complex Litigation explains:
Complexities may arise where the rulings turn on questions of substantive law. In diversity cases, the law of the transferor district follows the case to the transferee district. Where the claim or defense arises under federal law, however, the transferee judge should consider whether to apply the law of the transferee circuit or that of the transferor court’s circuit, keeping in mind that statutes of limitations may present unique problems.31
The case cited by the Manual for the statutes of limitations problem is Berry Petroleum Co. v. Adams & Peck32 in which the Second Circuit applied the law of the Fifth Circuit to determine if a suit has been timely brought. “Since this case was brought in a district [441]*441court in the Fifth Circuit, the substantive law of that circuit is the law we must consider here.”33 Just as the statute of limitations encompassed questions of state substantive law, whether to certify a class involves issues pertaining to state substantive law. Neither party should be prejudiced in preparing for trial because the case was removed and transferred to another district in a different circuit.
Thus, in considering a motion for class certification of state claims under Rule 23, the law of the transferor circuit controls because that is the law that will bind the trial court and class certification is an issue on which the Supreme Court has directed courts to ensure that the requirements of Rule 23 are satisfied for purposes of trial. For pretrial motions, it is appropriate to apply the law of the transferee court in order to avoid duplication, conflicting rulings and schedules, and increased litigation costs. But, in the context of class certification and other issues inherently enmeshed with the trial, applying the law of the transferor court “promote[s] the just and efficient conduct of such actions.” 34
III. CLASS CERTIFICATION REQUIREMENTS
In order to maintain an action on behalf of a class, Plaintiffs must satisfy Rule 23 of the Federal Rules of Civil Procedure. Plaintiffs must demonstrate that their proposed classes satisfy the four prerequisites of Rule 23(a), which are referred to as (1) numerosity, (2) commonality, (3) typicality, and (4) adequacy.35
Once these prerequisites are satisfied, Plaintiffs must show that the proposed classes are “maintainable” by fulfilling one of the three requirements of Rule 23(b).36 In this case, Plaintiffs rely on Rule 23(b)(3) on the ground that common issues of law and fact “predominate over any questions affecting only individual members” and the class actions are “superior to other methods of adjudication.”37
“[T]he class determination generally involves considerations that are enmeshed in the factual and legal issues comprising the plaintiffs cause of action,”38 and courts subject a motion for class certification under Rule 23 to a “rigorous analysis” to ensure that its requirements are satisfied.39 In the Seventh Circuit, this means that “[bjefore deciding whether to allow a case to proceed as a class action, therefore, a judge should make whatever factual and legal inquiries are necessary under Rule 23.”40
IY. TWO OF PLAINTIFFS’ SUBCLASSES SATISFY RULE 23
Of the four prerequisites that Plaintiffs must satisfy under Rule 23(a), Defendants argue that the Plaintiffs have failed to establish two of them: numerosity and typicality.41 [442]*442In addition, Defendants argue that Plaintiffs have not demonstrated that their classes are maintainable under Rule 23(b)(3) because common issues do not predominate over individual issues of causation and damages (i.e., establishing the harm caused to each individual member of the class) and a class action is not a superior method of adjudication.42
A careful review of Plaintiffs’ proposed classes and the evidence submitted shows that the two subclasses involving damages to class members’ property satisfy the requirements of Rule 23(a) and (b)(3) with respect to the alleged torts committed by the Companies. As explained below, courts have repeatedly recognized that such single-incident mass accidents are suitable for class-wide adjudication.43 In this case, Plaintiffs’ tort claims against the Companies arise out of a single release of gasoline prior to November 9,1988. This is “a single accident, caused by a single or few actors who released the chemical within a specific geographic location” and thus warrants class treatment.44
However, the subclass involving personal injuries arising from exposure to MTBE cannot be certified because common issues do not predominate over individual issues related to proximate causation. Although courts will often certify classes involving claims arising out of a mass accident (such as a plane crash or a building collapse) in which causation may be proven on a class-wide basis, they typically will not certify a class involving claims that arise out of mass exposure to a toxic product or chemical because causation must be proven on an case-by-case basis.45
Finally, a class action may not be maintained against the Parson Defendants for their alleged negligence in the testing of various water sources after the spill over the course of many years. There is no single event, accident, or course of conduct underlying the claims: no set of facts will establish the liability of the Parson Defendants for negligence on a class-wide basis. Under such circumstances, a motion for class certification will generally be denied.46
A. Numerosity
Rule 23(a) requires that the class be “so numerous that joinder of all members is impracticable.”47 “Impracticability does not mean impossibility, but instead requires plaintiffs to prove that it would be inconvenient and difficult to join all proposed members of the class.”48 “The court is not limited to considering merely the number of potential class members, but may make common-sense assumptions that support a finding of numerosity.” 49
Courts have repeatedly held that a putative class with more than forty members will presumptively satisfy this requirement.50 Indeed, courts in the Seventh Circuit have held that a class with less than thirty members can still satisfy the numerosity requirement51 Finally, if Plaintiffs cannot provide [443]*443exact numbers of the proposed class, a good faith effort is sufficient to establish the number of class members.52
Defendants object that the proposed classes do not satisfy the numerosity requirement, but this argument is belied by the number of people affected by the gasoline release. “Approximately 2,100 people live within a 1 mile radius of the November 1998 release point.”53 “There are over 1,000 private wells in Limestone Township, according to the Illinois Water Survey”54 and, as Defendants admit in their opposition papers, “483 residential wells have been sampled for gasoline constituents, most of which have been sampled multiple times.”55 Finally, when a public meeting was held in April 1994 by the Illinois Department of Public Health about the groundwater contamination, “about 400 people attended.”56
Plaintiffs do not need to identify each person affected by the release of gasoline or pinpoint the exact number of people in the class. Indeed, it would be impossible for Plaintiffs to do so at this stage because such an identification will necessitate findings of fact that the jury must resolve {e.g., where did the gasoline go after it was released?).57 Nonetheless, the evidence before the court supports a finding that more than four hundred people might be members of each of the proposed subclasses.58
Because joinder of all the people who could bring claims against the Companies because of the gasoline spill would be impracticable, the numerosity requirement has been satisfied. Indeed, the crux of Defendants’ argument with regard to numerosity seems to be that very few, if any, people were in fact harmed by the gasoline spill. For example, Defendants argue “the evidence is that Shell has connected [to a water source] almost all of the affected properties at Shell’s ex-pense____ Certification is unjustified and unnecessary.”59
Defendants’ arguments may turn out to be true: If Shell connected a property to an unaffected water source, this act may eliminate any damages to such property owners. Yet, the Court cannot make that determination without delving into the merits of the case, which it must avoid on a motion for class certification unless that determination is relevant to a Rule 23 requirement.60 Determining the extent of the damages, or whether certain conduct by Shell after the gasoline release mitigated those damages, is not a finding that needs to be made when considering numerosity. The proper time to make that determination will be on a motion for summary judgment,61 or as a matter of law at trial.62 Moreover, if Defendants are [444]*444correct in this, or other legal arguments, then they will prevail on a class-wide basis.
At this stage, the sole question with regard to numerosity is whether the class of people who may bring claims against the Companies is “so numerous that joinder of all members is impracticable,”63 not whether that class of people will ultimately prevail in those claims. In this case, the numerosity requirement is plainly satisfied for each of the three subclasses.
B. Commonality
“A common nucleus of operative fact is usually enough to satisfy the commonality requirement of Rule 23(a)(2).”64 The key question is whether a common question of fact and law is at the core of Plaintiffs’ claims.65 In this case, numerous common questions of fact and law are at the core of Plaintiffs’ claims against the Companies because Plaintiffs’ tort claims arise out of a single gasoline release.
Two examples show how common issues underlie class members’ allegations and claims. One fact question that a jury may need to resolve is how much gasoline was released. As Plaintiffs point out in their Complaint, it was originally announced that the release involved 16,000 gallons.66 Later, Shell estimated that 100,000 gallons had been released, but later revised that estimate downward to between 12,000 and 21,000.67 At the same time, the Illinois Environmental Protection Agency stated that the spill “resulted in the release of an estimated 120,000 gallons.”68 The amount of gasoline released is a factual issue common to every member’s claims, but one on which there appears to be disagreement and will need to be resolved.
Likewise, a key legal issue will involve the standard of care that the Companies should have used in building and maintaining the pipeline and whether that standard was breached. “The essential elements of a cause of action based on common law negligence may be stated briefly as follows: the existence of a duty owed by the defendant to the plaintiff, a breach of that duty, and an injury proximately caused by that breach.”69 In this case, an issue common to all members’ claims will be whether there is sufficient evidence to allow a reasonable jury to conclude that the duty was breached. Moreover, if there is such evidence, a jury will need to make that decision on a class-wide basis.
Because such factual and legal issues underlie the tort claims against the Companies, the commonality requirement of Rule 23 is satisfied.
C. Typicality
The typicality requirement “primarily directs the district court to focus on whether the named representatives’ claims have the same essential characteristics as the claims of the class at large.”70 “A plaintiffs claim is typical if it arises from the same event or practice or course of conduct that gives rise to the claims of other class members and his or her claims are based on the same legal theory.”71 A close nexus between the claims assures that the representatives will advance the interests of all class members because their motive to pursue their claims will be similar to those of the absent class members.
In this case, Plaintiffs have satisfied the typicality requirement because each class member’s claim arises from the same event: [445]*445the gasoline release in November 1988. As a result, Plaintiffs’ motivation to prove their claims is typical of all class members. For example, Plaintiffs have similar motivations as the rest of the class to prove that negligence led to the gasoline release and that the Companies are liable for damages suffered as a result. Nonetheless, Defendants object to the appointment of Panozzo and Kibbons as class representatives.72
Defendants make three arguments as to why Panozzo’s claims are not typical of the rest of the class. The first argument against Panozzo is that he “obtained his property not through an arms-length transaction, but rather through probate after this suit was filed.”73 Their second argument is that “his property was connected to the municipal water system in 1994, long before he acquired the property.”74
It is not sufficient, however, to oppose class certification by pointing to distinctions that make no difference. Defendants do not explain, and the Court is unable to discern, how the fact that Panozzo obtained the land through probate will affect his motivation to prove his tort claims, much less in a way that prejudices the class.75 Nor do Defendants explain how the fact that Panozzo’s property was connected to the municipal water system in 1994 will eliminate his motivation to prove liability and recover damages. As Plaintiffs argue, Panozzo should be motivated to pursue his claims against the companies because of the loss of the quiet enjoyment and value in his property.76 There is no reason to hold that his claims are atypical on the basis of the distinctions that Defendants have offered.
Defendants’ third argument warrants more attention. Defendants allege, and Plaintiffs do not contest, that Panozzo and his mother learned in 1994 that the groundwater well at the property was contaminated with MTBE. In Illinois, “actions ... to recover damages for an injury done to property, real or personal ... shall be commenced within 5 years next after the cause of action accrued.”77 “Resolution of- the statute of limitations issue will be central to an adjudication of Mr. Panozzo’s property damage claim.”78 Thus, Defendants argue, Panozzo’s claims are not typical because he must address this defense.79 The test is whether this defense will become the focus of the litigation, thereby overwhelming the common issues and prejudicing other class members.80
In this case, the fact that Panozzo must address the statute of limitations question makes it more likely, not less, that the interests of the class members will be fairly and adequately protected because many absent members are likely to be subject to the very same defense.81 As Plaintiffs plead in their Complaint, an announcement about the release was made on November 9, 1988—thir-[446]*446teen years before the Complaint was filed.82 Since then, the community around Limestone Township has undoubtedly been made aware of the spill in various ways including, but not limited to, public meetings and water testing.
A critical question to address for most, if not all, class members is when did “the[ir] cause of action accrue”83 and the limitations period start to run. The fact that Panozzo will need to overcome this defense only makes it more likely that he will adequately protect the interest of absent class members. This defense is neither unique to Panozzo nor will the fact that he must defeat it prejudice other class members.84 The typicality requirement is thus satisfied.
Finally, with respect to Lisa Kibbons and her son Evan, Defendants challenge her ability to represent a subclass of people exposed to gasoline contamination from the pipeline resulting in personal injury. In particular, they note that Plaintiffs “have not identified any other person who claims to have suffered from ADHD. The central issue regarding Evan’s claim will be whether exposure to MTBE is capable of causing ADHD....”85 Putting to the side that Plaintiffs have not alleged that Evan suffers from ADHD but rather alleges problems with his central nervous system,86 there is no need to resolve whether her claims are typical of the rest of the subclass because, as explained below, the subclass of people exposed to MTBE fails the predominance requirement of Rule 23(b)(3).87
D. Adequacy
A proposed class representative must “fairly and adequately protect the interests of the class.”88 Adequacy of representation involves determining whether (1) the named plaintiffs’ interests are antagonistic to the interest of other members of the class and (2) plaintiffs’ attorneys are qualified, experienced and able to conduct the litigation.89 Inquiring into the adequacy of the proposed class representative is meant “to uncover conflicts of interest between named parties and the class they seek to represent.”90 “A class is not fairly and adequately represented if class members have antagonistic or conflicting claims.”91
Panozzo and Kibbons are adequate representatives for proposed subclasses one and two. They suffered their alleged harms as a result of the same accident affecting all class members and they do not have any interests that are antagonistic or in conflict with the class. Plaintiffs’ attorneys are also well qualified to conduct this litigation given their vast experience in MTBE litigation.92 The Court is confident that these attorneys will adequately represent the Plaintiffs and the class.
[447]*447E. Maintainability
Because Plaintiffs seek to maintain three subclasses pursuant to Rule 23(b)(3), they must satisfy the two additional requirements imposed by that rule: predominance and superiority.93 The three subclasses are people who were harmed because:
(1) their real property was contaminated by gasoline resulting in loss of value and quiet enjoyment;
(2) their wells and other sources of water were contaminated by gasoline resulting in expenses associated with procuring uncontaminated water;
(3) they were exposed to gasoline contamination from the pipeline resulting in personal injury, or an increased risk of personal injury.94
The question for each of these subclasses is whether the common questions of law and fact predominate over individual issues, and if a class action is a superior method of adjudication in such a situation.
1. Subclasses One and Two Satisfy the Predominance Requirement
Courts have repeatedly drawn distinctions between proposed classes involving a single incident or single source of harm and proposed classes involving multiple sources of harm occurring over time. The former warrant certification, while the latter do not. For example, this Court has previously denied certification for a class alleging “contamination [of water sources with MTBE] over many years across four states indirectly caused by twenty defendants in conjunction with innumerable third parties who released the contaminant into the environment.”95 Nonetheless, the Court distinguished cases in which classes had been certified because “[i]n each of these cases ... the class representatives alleged a single accident, caused by a single or few actors who released the chemical within a specific geographic location.”96
In Amchem, the Supreme Court drew the same distinction. While denying class certification, the Court nonetheless stated that “mass tort cases arising from a common cause or disaster may, depending upon the circumstances, satisfy the predominance requirement.” 97 Accordingly, courts have certified classes claims arising out of a single event or course of conduct such as a train crash,98 a fire in a convention hall99 or nightclub,100 an explosion,101 food poisoning on a ship,102 a nuclear reactor accident,103 and chemical or radiation seepage onto adjoining property from a plant or waste burial site.104
[448]*448The difference between the former and latter is that proximate causation may be determined on a class-wide basis in a mass accident and the only question left to resolve relates to the damages for each member of the class. In contrast, proximate causation often cannot be resolve on a class-wide basis in the case of exposure to a chemical. Thus, class certification is often denied in such cases.105
The principle that supports class certification in all of these cases is the same: When liability can be resolved by a jury with a single decision that applies to the whole class, and the only individual question left to resolve relates to damages, class certification is warranted. “As this body of law shows, Rule 23(b)(3) certification is generally granted in a tort case where there is a demonstrated cohesiveness of the class due to a shared experience that is confined in time and place and produces similar effects. Where these elements are not present, certification is usually denied.”106
Indeed, in Mejdrech v. Metr-Coil Systems Corporation,107 the Seventh Circuit affirmed the certification of a class action in a case very similar to subclasses one and two. In Mejdrech, a lawsuit was brought against Met-Coil, which owned a factory in a town outside Chicago. Plaintiffs alleged that a storage tank on Met-Coil’s property had leaked chemicals into the soil and groundwater. Approximately one thousand members of the proposed class were within a mile or two of the factory.108 The leaking of the chemicals into the soil and groundwater impaired the value of their property and Plaintiffs sought relief under federal and Illinois environmental law.109 The district court limited class treatment to the “core questions” pertaining to liability and left for individual hearings the issue of whether “a particular class member suffered any legally compensable harm and if so in what dollar amount.” 110
The Seventh Circuit agreed that “not only the amount but the fact of damage might vary from class member to class member.”111 Nonetheless, it held that the action still warranted class certification.
If there are genuinely common issues, issues identical across all the claimants, issues moreover the accuracy of the resolution of which is unlikely to be enhanced by repeated proceedings, then it makes good sense, especially when the class is large, to resolve those issues in one fell swoop while leaving the remaining, claimant-specific issues to individual follow-on proceedings.
The holding in Mejdrech is persuasive and controlling. As explained above, there are many common factual and legal issues here that relate to each individual class member’s claims. Indeed, almost all of the factual and legal issues up until the moment when the pipeline released the gasoline will likely be identical. These common issues predominate in subclasses one and two because the determination of damages for each individual member of the class, if Plaintiffs establish that the Companies are liable for a particular tort, can be left “to individual follow-on proceedings.” 112
[449]*4492. Subclass Three Does Not Satisfy the Predominance Requirement
In contrast to subclasses one and two, proximate causation cannot be proven on a class-wide basis for subclass three, alleging personal injuries resulting from exposure to MTBE. While a jury might find that the Companies breached a duty of care when the MTBE-containing gasoline spilled, each member of the class exposed to the MTBE would still need to show that their personal injuries were proximately caused by such exposure. A jury could not make a class-wide determination because the exposure of each member will vary by, inter alia, the length of the exposure (e.g., someone who passed through the neighborhood versus someone who lives there) and by the method of exposure (e.g., ingestion versus inhalation). In addition, the medical evidence regarding causation as to the various alleged injuries will vary enormously.
In fact, a similar type of class was rejected by the Supreme Court in Amchem, which involved exposure to asbestos. As the Am-chem Court explained, class members “were exposed to different asbestos-containing products, in different ways, over different periods, and for different amounts of time; some suffered no physical injury, others suffered disabling or deadly diseases.”113 Such a class was not “sufficiently cohesive” under Rule 23(b)(3) because the disparities in the personal injuries suffered by class members were too great.114
Likewise, subclass three includes those people who were exposed to gasoline through (1) inhalation of gasoline vapor, (2) penetration of the skin and absorption from showering, bathing or swimming, or (3) through “consumption of, among other things, drinking water and food mixed with water (i.e., baby formula).”115 The personal injuries suffered from such exposure may include (1) liver problems, (2) central nervous problems, (3) cardiac irregularities, (4) various forms of cancer, (5) chronic hepatitis, (6) facial twitching, (7) fatigue, (8) nausea, or (9) chest pains.116 Moreover, the class also includes any person who suffered an increased risk of any one of these injuries.117 While these may, in fact, be injuries that people have suffered from exposure to MTBE, the disparities in the injuries, and the questions of whether the gasoline caused such injuries, are too great to satisfy Rule 23(b)(3)’s predominance requirement.118
3. Subclass One and Two Satisfy the Superiority Requirement
Finally, with respect to subclasses one and two, a class action is plainly superior to other methods of adjudicating. Superiority is established when “a class action would achieve economies of time, effort, and expense, and promote uniformity of decision as to persons similarly situated, without sacrificing procedural fairness or bringing about other undesirable results.”119 In this [450]*450case, trying each individual plaintiffs action separately would only lead to wasteful repetition given, for example, that the proof regarding the history of the pipeline’s operation and maintenance, the development and use of MTBE and the availability of safer alternative chemicals by the Companies, the migration of the gasoline, and the effects of MTBE contamination will all be identical after the release will be identical.
4. Summary
Because common issues pertaining to liability predominate over individualized determinations of damages, and a class action is a superior method of resolving these issues, Rule 23(b)(3) has been satisfied for subclasses one and two. However, Rule 23(b)(3) has not been satisfied for subclass three because common issues do not predominate over individual determinations of proximate causation related to personal injuries allegedly suffered by those exposed to MTBE.
Y. PLAINTIFFS’ CLASSES DO NOT SATISFY RULE 23 WITH RESPECT TO THE NEGLIGENCE CLAIM AGAINST THE PARSON DEFENDANTS
Plaintiffs’ request to certify a class against the Parson Defendants also demonstrates the critical distinction between a class based on a single incident or course of conduct over a defined period of time, and a class based on multiple sources of harm that occurred over differing periods of time in different places. In this case, Plaintiffs base their negligence claims against the Parson Defendants on allegations that the Parson employees who “directed, supervised or took water samples from plaintiffs [sic] well and other private water supply wells within the area affected by the release ... likely followed a procedure that did not draw down well water by sustained pumping____”120 However, Plaintiffs only name two of the employees who took water samples and do not say when these employees took the samples. Rather, Plaintiffs allege that the “water sampling by the Parsons during the period 1994 to the present time took place at various times on a twice-a-month basis, or monthly, or every second or every third month.” 121
The fundamental problem with the Plaintiffs’ motion to certify a class against the Parson Defendants is that Plaintiffs have not presented any theory or evidence that will establish the defendant’s liability for negligence on a class-wide basis, and thus Plaintiffs have failed to satisfy Rule 23(b)(3) because common issues do not predominate over the individual ones.122 Ribbons and Panozzo might well establish that the employees who took water samples from their personal wells acted negligently, but it would not follow from this finding that other employees at different times and different places also acted negligently towards the people whose wells they sampled.123
[451]*451The Seventh Circuit has explained that bifurcation of trial is permissible when the divisions “carve at the joint” between liability and damages.124 In this case, however, each member of the class would still need to prove that the particular employee who tested the samples from their water source was negligent even though the claims of every member might share certain factual and legal characteristics ie.g., the Parson Defendants were testing for the presence of MTBE). When liability must be proved on a case-by-case basis, the Seventh Circuit has held that courts may not certify the class.125
Because Plaintiffs have failed to satisfy the predominance requirement of Rule 23(b)(3) for their negligence claim against the Parsons Defendants, class certification is denied.
VI. CONCLUSION
For the reasons discussed above, Plaintiffs’ motion to certify subclasses one and two against the Companies for the claims of trespass, private nuisance, negligence, and strict liability is granted. The motion to certify subclass three is denied. Finally, the motion to certify a class action against the Parson Defendants is denied. The Clerk of the Court is directed to close this motion (Docket No. 1066).