The critical issue presented by this appeal concerns the specificity of proofs required to entitle plaintiff to a jury trial on the question whether decedent’s stomach and liver cancer was proximately caused by prolonged, frequent and repetitive exposure to defendants’ petroleum and chemical products that contained no warning of their hazardous propensities. Defendants contend that the lack of proof of the specific content of their individual products *285 and lack of proof of specific exposure to each product justified the Law Division’s grant of summary judgment.
Over the course of his twenty-six years of employment with Bessemer Processing Company, Inc. (Bessemer), decedent Walter James (James) was exposed on a daily basis to a wide array of residues of petroleum- products and other chemical substances, many allegedly containing benzene, polycyclic aromatic hydrocarbons and other human carcinogens. On February 8, 1990, at the age of fifty-two, James died of stomach and liver cancer. James’s widow, plaintiff Ida James, brought this survivorship and wrongful death action against multiple defendants, alleging that they failed to warn of the dangerous propensities of the substances they shipped to Bessemer and that James’s continuous exposure to those substances was the cause of his illness and death.
The Law Division granted summary judgment to all defendants on the ground that plaintiff would be unable to establish that James’s cancer was caused by specific products manufactured by specific defendants. That court issued separate orders dismissing plaintiffs complaint against various defendants on procedural grounds. The Appellate Division reversed the summary judgment order dismissing plaintiffs complaint against all named defendants.
James v. Chevron U.S.A., Inc.,
301
N.J.Super.
512, 522-23,
The primary issue posed by this appeal is whether a plaintiff in a toxic-tort, failure-to-warn case can establish a
prima facie
case on the element of “medical causation” by satisfying the “frequency, regularity and proximity” test pronounced by the Appellate Division in
Sholtis v. American Cyanamid Co.,
238
N.J.Super. 8,
I
As this appeal arises from the Law Division’s order of summary judgment in favor of defendants, we review the evidentiary record
*287
in a light most favorable to plaintiff.
Brill v. Guardian Life Ins. Co.,
142
N.J.
520, 540,
The reconditioning process that took place at Bessemer was multi-staged and, according to Bessemer employees, each stage of the process exposed the workers to noxious fumes and chemicals. The first stage of the process was the emptying of the drums. Although by federal regulation the “empty” drums sent by oil producers were supposed to have no more than one inch of residue, Bessemer employees indicated in depositions that most drums contained as much as four or five gallons of waste material when they arrived at the Bessemer plant. The drums were first brought to the “cutting room” where workers uncapped the heads of the drums. The noxious fumes from the chemicals in the drums pervaded the cutting room, and workers in that room could not avoid inhaling those fumes. After the drums were uncapped, as much residue as could be removed prior to incineration and blasting was dumped into a “slop hole,” a pit approximately six- *288 feet deep that collected beneath a conveyor. During this emptying process, waste material from the drums frequently spilled onto the skin and clothing of the workers. Twice a month, workers would empty or clean out the slop hole, partly with the aid of a front-end loader, and partly by removing the residue manually with shovels and buckets. James was frequently involved in cleaning out the slop hole, both as an operator of the front-end loader and manually with a shovel.
Next, the uncapped drums were turned upside down and placed on a drag-chain conveyor that transported them through a “tunnel incinerator” operated by Bessemer workers where the remaining residue in the drums was burned and charred by high temperature flames. The “strong and foul” smell of the burning chemicals permeated the area surrounding the incinerator and those workers who operated it inhaled the emanating fumes. The drums were then sand blasted to remove all of the charred material, releasing dust and fumes into the air to which the workers also were exposed. The drums were then washed with nitrate and soda, straightened by a “rolling machine,” sealed by a “head up machine” or “heading machine,” welded by a welding machine, and tested for holes by a steamer machine. The drums were then rewashed, placed in an oven to dry, and then painted by Bessemer employees. Following the completion of the reconditioning process, the drums were either resold or returned to the suppliers for reuse.
During his employment with Bessemer, James functioned predominantly as a “utility man,” available to fill in for absent workers at any position in the plant as required by his employer. Daniel Stewart, who worked for Bessemer from 1949 until 1984, indicated that he saw defendant perform every job required at the Bessemer plant, including cutting the heads off drums; operating the incinerator, sand blaster, rolling machines, and heading machines; welding and painting drums; and, as previously described, cleaning the slop hole. James was diagnosed with stomach cancer in October 1989. He died at the age of fifty-two on February 8, *289 1990. The cause of his death was “carcinoma with metastasis to the liver and peritoneum.”
Due to a lack of business, Kingsland and Bessemer ceased operations in June 1992. The business records that had been kept at Bessemer throughout the period of James’s employment were “production documents” that indicated the number of drums that had been reconditioned. However, they did not indicate the name of the corporate customer that had provided to Kingsland the drums that were reconditioned at Bessemer, nor did they indicate the specific chemical residue contained in any particular drum. All' other records were kept at Kingsland, including bills of lading and billing invoices indicating the number of drums picked up by Kingsland drivers from a specific customer, but not reflecting the content of the empty drums. Pursuant to the requirements of the Resource Conservation Recovery Act (RCRA), 42 U.S.C.A. § 6901, et seq., each shipment of drums picked up by Kingsland contained a certification from the supplier of the drums attesting that the supplier used its best efforts to remove the residue in the drums. However, the RCRA certifications did not indicate the nature of the residue in the drums.
Beginning some time in the late 1980s, around the time that James was diagnosed with cancer, Kingsland began receiving Material Safety Data Sheets (MSDSs) from both the companies supplying drums for reconditioning and the companies supplying various products used in the reconditioning process. The MSDSs contained warnings of and safety instructions regarding the hazards of the residues and products received. However, although such MSDSs were provided for each substance that Kingsland potentially might receive, they did not necessarily indicate which specific products or residues a supplier had provided to Kingsland or in what quantities drums containing such residues may have been supplied. Kingsland officials indicated that all records generally were kept for three years and then destroyed. At some time within a few months after the cessation of operations at Kingsland and Bessemer in June 1992, Kingsland representatives *290 destroyed all of the existing records that may have been pertinent to this litigation. Those defendant suppliers and manufacturers that responded to plaintiffs interrogatories all indicated that they knew of no records kept by their companies indicating the quantities, trade names or chemical compositions of any of the residues contained in drums sent to Bessemer by Kingsland for reconditioning.
Many of the drums that arrived at Bessemer had labels that listed the contents of the drum, displayed the name of the manufacturer of the contents, and contained some general health warnings that became more specific around the late 1980s. Those labels were removed as part of the incineration process. In November 1989, Kingsland received a citation from the Occupational Safety and Health Administration (OSHA) for failure to have a hazardous communication plan describing to its workers the hazards of residues contained in the drums with which they worked daily.
Because of the lack of documentation concerning the identity of the suppliers of the drums that were reconditioned at Bessemer and the identity of the material in those drums, plaintiff was required to rely predominantly on the memory of Bessemer employees and executives in her efforts to obtain discovery regarding that information. Before joining Bessemer as a defendant in this action, plaintiff served interrogatories on Bessemer, one of which asked for. the identity of the chemical compositions and trade names of all of the substances to which James was exposed during his employment with Bessemer. Bessemer answered by explaining that James
was subject to exposure from any type of material that might be shipped in 55 gallon steel drums, except herbicides, pesticides and hazardous materials described in 49 C.F.R. § 261.33(e)(acutely hazardous materials). Empty drums whose previous contents held the aforementioned material were not accepted at Bessemer. The majority of the empty drums, from 1960 to the mid eighties would have contained petroleum based products. From the early eighties to 1989, the mixture of the drum residues became highly varied, and included but [was] not limited to: resins, dyes, paints, solvents, fragrances and unknown substances.
*291 Plaintiff deposed Glenn Richard, the environmental and regulatory affairs officer for both Kingsland and Bessemer between 1984 and 1992, who identified Shell, Exxon, Chevron, Texaco, Sunoco, CITGO, Gulf and Mobil as entities that historically had provided drums to Kingsland. He testified that those drums generally contained residues from finished oil products or from raw material constituents of finished products. Richard further indicated that although Kingsland never dealt directly with Amoco, the Kings-land and Bessemer plants may have received for reconditioning drums containing residues of Amoco products. Richard identified Ashland Chemical, American Cyanamid Company, MacArthur Petroleum and Mellen Chemicals (acquired in 1990 by defendant Pride Solvents & Chemical Company) as entities that supplied drums containing chemicals and solvents. He indicated that Pope Chemical sent drums containing residues of blue and yellow dyes, and that North American Paint, Pan Chemical, Whittaker Chemical and Rising Star Coating provided the paints and liners used in the reconditioning process. Richard indicated that during peak years as many as 150,000 drums per year were sent to Bessemer for reconditioning, with 1,200 drums being reconditioned on a “good day.”
Irving Klein, president and half-owner of Bessemer, who began working for Kingsland as a salesman in 1954, indicated that Texaco, Exxon and Shell were Kingsland’s three biggest customers, with CITGO, Mobil and Sunoco not far behind. Klein testified that Texaco, Exxon, Shell and CITGO were customers for approximately forty years, American Cyanamid Company for thirty-five years, and Pope Chemical for over twenty years. Chevron and Baker Lite Company had been customers for approximately twenty-five years. Ashland Chemical and Prime Lube, an entity that filled orders for Amoco and Arco, had been customers for six years, MacArthur Petroleum & Solvent and Mellen Chemicals for four years, and Mobil for two years. Klein also recalled buying paint from North American Paint and Rising Star Coating, as well as selling reconditioned drums to North American Paint. Klein *292 did not identify Occidental or Linde Gases as customers or suppliers.
Plaintiff deposed or received statements from five former Bessemer employees, each of whom had some recollection of the nature of the substances to which the employees were regularly exposed, as well as the manufacturers and/or suppliers of those substances. Daniel Stewart regularly observed drums from Shell, Exxon, Chevron and Texaco that generally contained gasoline and motor oil, and recalled that other entities that regularly supplied drums included American Cyanamid, Hooker Chemical, Roman Heart and Baker Lite. Stewart’s certification stated that virtually all of the 55-gallon drums received by Bessemer had product residue left inside, usually amounting to four or five gallons of residue material, and that all drums emitted strong odors. The odor from some drums was so foul that they had to be stored outside for two to three days before they could be processed.
Roosevelt Lewis, a Bessemer employee from 1963 until 1992, testified at deposition that he saw drums from Shell, Texaco, Chevron, Exxon, Sunoco, Amoco, Mobil, CITGO, American Cyan-amid and Pope Chemical “every day” at the Bessemer plant. He recalled that the drums from the petroleum defendants contained residues including light and dark oils, gasoline, and antifreeze. He recognized the gasoline and oil residues by sight and smell, describing the oil residues as “burned, black and sticky,” and noting that the fumes from the drums sent by Exxon, Shell, Texaco and CITGO were “pretty strong,” and that drums from those manufacturers at times contained “quite a bit of residue.” He indicated that the drums from Pope contained blue, black and green dyes. On cross-examination, Lewis indicated that not all of the drums had labels, but that he identified some regular suppliers based on overhearing the dispatcher who sent trucks to the suppliers for pickups.
Eddie Kennedy, who worked at Bessemer for the entire period of its operations, recalled seeing on a regular basis drums from Chevron, CITGO, Mobil, Texaco, Exxon, Sunoco, Shell, Amoco and *293 Gulf that contained “oil residue which was light to dark black in color.” He described “frequently” seeing Texaco drums containing oils, black oils and gasoline.
Thomas Mewborn, a maintenance man and shop steward at Bessemer from 1977 until 1992, often unloaded drums arriving at the plant that contained gasoline, crude oil, diesel fuel, hydraulic oil and antifreeze. Although he could not specifically recall which entities supplied drums containing which residues, Mewborn regularly observed drums from Exxon, Shell, Texaco and CITGO. Johnny Ramey, a Bessemer employee from 1976 until 1990, recalled seeing drums from Exxon, Shell, Texaco, Chevron, Gulf, and CITGO. He testified specifically that the Exxon drums contained gas and oil, and he described using oil residue from some of the drums to operate his personal car.
James Davis, James’s brother-in-law, worked as a drum inspector at Kingsland from 1965 until 1990. He recalled that the drums forwarded to Bessemer included drums from Texaco, Shell, Exxon, Mobil, Chevron and Sunoco. Those drums contained such substances as heavy industrial oil, machine oil, transmission oil, motor oil and antifreeze. Davis also traveled approximately once a week to the Bessemer plant, where he recalls having seen drums from those oil companies, as well as from American Cyanamid and Hooker Chemical. Davis recalled drums from Hooker Chemical that emitted such a strong and foul odor that employees needed to wear masks in order to handle the drums.
Additionally, Lewis, Kennedy, Mewborn and Davis each recalled seeing drums containing formaldehyde residue, but could not identify the entity or entities that supplied those drums. Mew-born indicated that the fumes from the formaldehyde drums were particularly strong, and that employees handling those drums would wear charcoal filter masks. Lewis, Kennedy and Stewart each observed drums containing embalming fluid, but could not identify the entity or entities from which those drums came.
In addition to the information elicited during discovery from lay witnesses, the record before the Law Division on defendants’ *294 motion for summary judgment included the reports of plaintiffs toxicological, medical and economic experts. Plaintiffs expert in toxicology, Dr. Myron Mehlman, reviewed summaries of James’s medical records, summaries of deposition transcripts and witness statements, as well as scientific, governmental and medical literature on the carcinogenicity of various chemicals to which James was exposed during his employment at Bessemer. Dr. Mehlman cites several studies dating back as far as 1928 indicating the health risks of benzene exposure and describes decades-old epidemiological studies revealing a causative link between cancer and exposure to benzene and polycyclic aromatic hydrocarbons (PAHs) found in gasoline and petroleum products.
The toxicologist’s report explains that “[bjenzene is present in many petroleum products, petroleum distillates, jet fuels, diesel fuels, crude oil, and is a significant component of gasoline (up to 6%),” and that “[bjenzene is currently classified by the Environmental Protection Agency (EPA), the American Conference of Governmental Industrial Hygenists (ACGIH), and IARC [the International Agency for Research on Cancers] as a human carcinogen.” The report adds that “[ajnimal studies ... have clearly and without question demonstrated the carcinogenic effects of benzene____”
Dr. Mehlman indicated that “PAHs are a group of chemicals that are present in oil, petroleum products, and tobacco smoke. There are more than 100 different PAH compounds. Usually humans are not exposed to an individual PAH alone, but to a mixture of PAHs.” The report indicates PAHs can enter the body through inhalation or skin contact, and that the primary exposure to PAHs occurs in the workplace. Many of the PAHs have been found to cause cancer in animals, and “[rjeports on humans show that individuals exposed to PAHs by inhalation or skin contact for long periods [or] to mixtures that contain PAHs and other compounds can also develop cancer.” The Department of Health and Human Services has determined that six PAH compounds are carcinogens. IARC classifies thirteen PAH compounds as “having *295 sufficient evidence for carcinogenicity (meaning they are human carcinogens).” The EPA has also determined that those thirteen PAH compounds are “probable human carcinogens,” meaning that they more likely than not cause cancer.
Based on the testimony of Bessemer workers and thé MSDSs provided in discovery by Shell and Exxon, Dr. Mehlman determined that the chemicals and products to which James was exposed included black oils, motor oils, PAHs, solvents and formal-dehydes. He noted that many of the MSDSs provided by Exxon “indicate that numerous products contained extremely high levels of benzene and PAHs.” Based on the evidence obtained by plaintiff during discovery and on numerous epidemiological and animal studies, Dr. Mehlman concluded that
workplace exposures to various petroleum products (i.e., benzene, gasoline, mineral spirits, mineral oils) and chemicals, which contain gasoline, aromatic hydrocarbons, such as benzene, toluene, xylene, ethyl benzene, naphtha, acrylonitrile, formaldehyde, polycyclic aromatic hydrocarbons (i.e., benzo-alpha-pyrene), light cat-cracked naphtha (“LCCN”) and other chemicals caused Mr. James to suffer from stomach and liver cancer.
Plaintiff also presented two reports of her medical expert, Dr. Rowland Goodman. Relying on the evidence obtained during discovery and on the report of the toxicological expert, Dr. Goodman concluded that
the patient absorbed one or more of these carcinogens through his gastrointestinal tract and through his lungs. These chemicals then spread to his stomach causing a derangement of the DNA mechanism such that one or more of the cells grew in an uncontrolled fashion clinically known as cancer.
Finally, plaintiff offered the report of an economic expert, Dr. Frank Tinari, who estimated “the total present value of the projected losses resulting from the death of Walter James” at $1,243,830. That amount included estimated values for loss of income, loss of household services, and loss of companionship to plaintiff.
II
As an “environmental tort action,” defined by statute as a “civil action seeking damages for harm where the cause of the
*296
harm is exposure to toxic chemicals or substances,” this action is excluded from coverage under the 1987 Product Liability Act,
N.J.S.A.
2A:58C-lb(4). In cases to which the act does not apply, plaintiffs may resort to common law causes of action.
Becker v. Baron Bros.,
138
N.J.
145, 151,
[U]nder strict liability, the seller’s knowledge is presumed; it is “assume[d] the seller knew of the product’s propensity to injure as it did.” In negligence cases, such knowledge must be proved; the standard is what the manufacturer “knew or should have known.”
[Id. at 239,432 A.2d 925 (quoting Phillips v. Kimwood Machine Co., 269 Or. 485,525 P.2d 1033 , 1039 (1974)).]
Here, plaintiff alleges that defendants failed to warn James of the dangerous propensities of their products, the residues contained in the drums sent for reconditioning, and the products sold for use in the reconditioning process, and that those products were the cause of James’s cancer and of his death from that illness. She asserts both striet-liability and negligence claims.
A
This Court set forth the elements of a cause of action for strict liability in the context of a products-liability, failure-to-warn claim in
Coffman v. Keene Corp.,
133
N.J.
581, 593-95,
[t]o establish a cause of action in strict liability for a defective product, a plaintiff must prove that the defect existed when the product left the defendant’s control and that the defect caused injury to a reasonably foreseeable user. In a failure-to-warn case, the alleged product defect is not a flaw in the structure or design of the product itself. Rather, the defect is the absence of a warning to unsuspecting users that the product can potentially cause injury. Nevertheless, the same elements to establish a cause of action apply when a plaintiff’s claim concerning a defective product is based on a failure to warn.
[Id at 593-94,628 A.2d 710 (citations omitted).]
*297
Just as in this case, the failure-to-warn claim in
Coffman
arose from an occupational exposure over many years to the products of multiple manufacturers, in that case asbestos products, that led to the plaintiffs illness.
Id.
at 590-92,
[ciausation is a fundamental requisite for establishing any product-liability action. The plaintiff must demonstrate so-called product-defect causation — that the defect in the product was a proximate cause of the injury. When the alleged defect is the failure to provide warnings, a plaintiff is required to prove that the absence of a warning was a proximate cause of his harm.
[Id. at 594,628 A.2d 710 .]
However, we also adopted in Coffman a rebuttable “heeding presumption” in products — liability, failure-to-warn cases. We held that
with respect to the issue of product-defect causation in a product-liability case based on a failure to warn, the plaintiff should be afforded the use of the presumption that he or she would have followed an adequate warning had one been provided, and that the defendant in order to rebut that presumption must produce evidence that such a warning would not have been heeded.
[Id at 603,628 A.2d 710 .]
We stressed that the effect of the heeding presumption would be to “direct factual inquiries to the real causes of injury in a failure-to-warn case.”
Id.
at 601,
As a result of the heeding presumption, the burden on a plaintiff to establish product-defect causation in the failure-to-warn context is not an onerous one. Initially, the plaintiff must establish that the defendant had a duty to warn. To establish such a duty, the plaintiff must satisfy “a very low threshold of proof in order to impute to a manufacturer sufficient knowledge to
*298
trigger the duty to provide a warning of the harmful effects of its product.”
Id.
at 599,
As noted by the court below, the fact that Bessemer may have failed its employees by not warning or instructing them regarding the hazards of toxic exposure in the workplace does not necessarily relieve defendants from liability for failure to warn.
James, supra,
301
N.J.Super.
at 539-41,
to overcome the heeding presumption in a failure-to-warn case involving a product used in the workplace, the manufacturer must prove that had an adequate warning been provided, the plaintiff-employee with meaningful choice would not have *299 heeded the warning. Alternatively, to overcome the heeding presumption, the manufacturer must show that had an adequate warning been provided, the employer itself would not have heeded the warning by taking reasonable precautions for the safety of its employees to take measures to avoid or minimize the harm from their use or exposure to the dangerous product.
[7d at 609,628 A.2d 710 .]
Whether either James or his superiors at Bessemer would have heeded warnings from defendant manufacturers had adequate warnings been provided over the course of James’s employment and exposure is a question for the jury, and the burden of proof on that issue lies with defendants.
B
In a toxic-tort action, in addition to product-defect causation a plaintiff must prove what is known as “medical causation” — that the plaintiffs injuries were proximately caused by exposure to the defendant’s product. See
Becker, supra,
138
N.J.
at 152,
This Court has emphasized for over a decade the “extraordinary and unique burdens facing plaintiffs who seek to prove causation in toxic-tort litigation.”
Rubanick v. Witco Chem. Corp.,
125
N.J.
421, 433,
By far the most difficult problem for plaintiffs to overcome in toxic tort litigation is the burden of proving causation. In the typical tort case, the plaintiff must prove tortious conduct, injury and proximate cause. Ordinarily, proof of causation requires the establishment of a sufficient nexus between the defendant’s conduct and the plaintiffs injury. In toxic tort cases, the task of proving causation is invariably made more complex because of the long latency period of illnesses caused by carcinogens or other toxic chemicals. The fact that ten or twenty years or more may intervene between the exposure and the manifestation of disease highlights the practical difficulties encountered in the effort to prove causation.
[Id. at 585,525 A.2d 287 .]
Legal scholars have long struggled with the problem of adapting traditional legal doctrines of causation to the difficulties of proving medical causation in the toxic-tort context, but courts have been resistant to novel models of causation. See, e.g., Margaret A. Berger, Eliminating General Causation: Notes Towards a New Theory of Justice and Toxic Torts, 97 Colum. L.Rev. 2117 (1997); David M. Benjamin, Elements of Causation in Toxic Tort Litigation: Science and Law Must Agree, 14 J. Legal Med. 153 (1993); Susan R. Poulter, Science and Toxic Torts: Is There a Rational Solution to the Problem of Causation?, 7 High Tech. L.J. 189 (1992); Christopher L. Callahan, Establishment of Causation in Toxic Tort Litigation, 23 Ariz. St. L.J. 605 (1991); Paul K. Sidorenko, Evidentiary Dilemmas in Establishing Causation: Are Courts Capable of Adjudicating Toxic Torts?, 7 Cooley L.Rev. 441 (1990); L. Grant Foster, A Case Study in Toxic Tort Causation: Scientific and Legal Standards Work Against Recovery for Victims, 19 Envtl. L. 141 (1988); Ora Fred Harris, Jr., Toxic Tort Litigation and the Causation Element: Is There Any Hope of Reconciliation?, 40 Sw. L.J. 909 (1986). In our toxic-tort precedents, this Court has tried to strike a balance with regard to proof of causation that is fair to both plaintiffs and defendants in view of the almost certain lack of direct scientific proof in such eases.
The problem of proving medical causation with respect to a specific defendant’s products is further compounded where, as
*301
here, a plaintiff has been exposed to multiple products of multiple defendants over an extended period of time.
See, e.g., Sholtis, supra,
238
N.J.Super.
at 14-16,
In the instant case, it is impossible, as a practical matter, to determine with absolute certainty which particular exposure to asbestos dust resulted in injury to Borel. It is undisputed, however, that Borel contracted asbestosis from inhaling asbestos dust and that he was exposed to the products of all the defendants on many occasions. It was also established that the effect of asbestos dust is cumulative, that is, each exposure may result in an additional and separate injury. We think, therefore, that on the basis of strong circumstantial evidence the jury could find that each defendant was the cause in fact of some injury to Borel.
Consistent with the reasoning of the court in
Borel,
and borrowing language from the Fourth Circuit’s opinion in
Lohrmann v. Pittsburgh Corning Corp.,
In the context of occupational asbestos-exposure cases, the “frequency, regularity and proximity test” first pronounced in
Lohrmann, supra,
We stress that the “frequency, regularity and proximity” test bears no relationship to theories of collective liability that some courts have adopted in contexts where the specific tortfeasor or tortfeasors that caused the plaintiffs injury cannot be identified. The “frequency, regularity and proximity” test assigns liability only to those defendants to whose products the plaintiff can *303 demonstrate he or she was intensely exposed. The court in Sholtis invoked the apt analogy of a multi-vehicle accident:
What we have before us are not products of unknown manufacturers whose responsibility must be reconstructed by reference to industry market percentages, but rather known manufacturers’ products whose contact with plaintiff must be proven or reasonably approximated by inference____ This situation bears some resemblance to a plaintiff being injured in a multi-vehicle accident caused by several culpable parties, whose conduct and defective products all contributed to the eventual injuries.
[Sholtis, supra, 238 N.J.Super. at 25,568 A.2d 1196 .]
The court below rejected defendants’ contention that the “frequency, regularity and proximity” test pronounced in Sholtis should be limited to cases involving asbestos exposure, holding that
at least for summary judgment purposes, we are convinced that the Sholtis analysis is relevant to the “medical causation” issue in a toxic-tort case, such as this, involving occupational exposure to cancer-causing substances manufactured by a determinant number of defendants, all of whom, it is alleged, acted tortiously by failing to warn of the dangerous propensities of their products.
We recognize that the dynamics and causative effects of exposure to asbestos dust may differ from the disease process resulting from exposure to chemicals containing known carcinogens. However, these differences should not cause rejection of the “frequency, regularity and proximity” model. Based on circumstantial evidence, the jury may find in any toxic-tort case, that a plaintiff in the workplace was exposed to the cancer-causing products of defendanhmanufacturers on many occasions, and that the exposures were a substantial factor in causing plaintiffs cancer. Application of the “frequency, regularity and proximity” test necessarily focuses on the cumulative effects of exposure to the carcinogen over a prolonged period of time, the dosage of exposure and mode of absorption into the human body. Bernard D. Goldstein and Mary Sue Henifin, Reference Manual on Sci. Evid. 181 (Federal Judicial Center 1994)____ Whether the claim is asbestosis or stomach cancer, the frequency, regularity and proximity of exposure will be an important and fundamental factual link in plaintiffs experts’ analysis and methodology in reaching an ultimate theory of causation.
[James, supra, 301 N.J.Super. at 529-30,694 A.2d 270 .]
The court further noted a Pennsylvania appellate court decision in which a “frequency and regularity” of exposure standard was applied to the determination of the sufficiency of a complaint seeking damages for workplace exposure to carcinogens (cadmium).
Id.
at 530 n. 4,
*304 We agree with the reasoning and conclusion of the Appellate Division, and hold that a plaintiff in an occupational-exposure, toxic-tort case may demonstrate medical causation by establishing: (1) factual proof of the plaintiffs frequent, regular and proximate exposure to a defendant’s products; and (2) medical and/or scientific proof of a nexus between the exposure and the plaintiffs condition.
Ill
A
That plaintiff has provided prima facie proof of “product-defect causation” is quite clear, and is not a significant focus of defendants’ claims on appeal. Defendants have not rebutted the heeding presumption. Although they eventually may be able to convince a jury, in view of Bessemer’s history of apparent disregard for the health of its workers throughout the period of James’s employment, that even an explicit warning of the health risks posed by regular exposure to defendants’ products would not have been heeded, that fact has not been established. Therefore, to proceed with her strict-liability claim, plaintiff is required to demonstrate only that knowledge of the potential hazards of exposure to defendants’ products existed within the petroleum and chemical industries at the relevant times. Plaintiff’s expert in toxicology cited numerous scientific studies, several predating the start of James’s employment at Bessemer in 1963, indicating the serious health threat posed by exposure to benzene. A 1948 report from the American Petroleum Institute indicated that “it is generally considered that the only absolutely safe concentration for benzene is zero.” The toxicologist’s report further referenced studies dating back to the 1950s demonstrating the carcinogenicity of PAHs. In conjunction with plaintiff’s evidence demonstrating that sufficient warnings were not provided regarding the health risk posed by the residues in the empty drums supplied to Bessemer, the scientific studies referred to in the toxicologist’s report clearly are sufficient to survive summary judgment on the *305 element of product-defect causation. The evidence is also sufficient to present a fact question for the jury regarding whether each individual defendant knew or should have known of the potential hazards of its products. Thus, plaintiff’s negligence claim also survives summary judgment on the element of product-defeet causation.
B
We next turn to the question whether plaintiff has established evidence on medical causation sufficient to withstand defendants’ motion for summary judgment. We held in
Brill, supra,
142
N.J.
at 523,
when deciding a motion for summary judgment under Rule 4:46-2, the determination whether there exists a genuine issue with respect to a material fact challenged requires the motion judge to consider whether the competent evidential materials presented, when viewed in the light most favorable to the non-moving party in consideration of the applicable evidentiary standard, are sufficient to permit a rational factfinder to resolve the alleged dispute in favor of the non-moving party.
The deposition testimony and sworn statements of James’s co-employees,
supra
at 286-287, 292-293,
The reports of plaintiffs experts,
supra
at 294-295,
That plaintiff was unable, and likely will be unable at trial, to precisely identify by either product name or chemical composition the exact petroleum products to which James was exposed is an insufficient basis for the Law Division’s order granting summary judgment in favor of the petroleum defendants. Representatives of those petroleum defendants that plaintiff had the opportunity to depose indicated that they kept no records of the precise residues contained in the drums that were provided to Kingsland for reconditioning. Even the MSDSs provided by defendants that, crediting plaintiffs proofs, were supplied only toward the very end of James’s employment with Bessemer, did not indicate how many drums containing residues of any particular product were provided to Bessemer. Those recordkeeping failures cannot be viewed as defeating plaintiffs failure-to-wam claim; they are more reasonably viewed as indicative of an unfortunate lack of care and responsibility on the part of those defendants with regard to the hazards posed by intense exposure to petroleum products containing benzene and PAHs. Although the lack of adequate records identifying the specific chemical properties of the specific products of each of the petroleum defendants severely hampered plaintiffs ability to satisfy the “frequency, regularity and proximity” standard, it did not preclude plaintiffs reliance on the recollection of lay witnesses to meet that standard.
We hold that plaintiffs proofs provided sufficient product identification with regard to the petroleum defendants to survive summary judgment. Plaintiffs toxicologist could rely on the physical descriptions of James’s co-workers to support his expert opinion that the fumes and residues described were of petroleum-based products containing sufficiently high levels of benzene and PAHs *308 to cause James’s cancer. Jurors could rely both on that expert opinion and on the factual testimony of the lay witnesses to determine whether plaintiff proved exposure to such petroleum-based products. A rational factfinder also could conclude from the co-workers’ testimony that James was frequently, regularly and proximately exposed to products of each of the petroleum defendants containing those known carcinogens, and thus could con-elude that James’s exposure to the petroleum products of each defendant was a substantial factor in causing or exacerbating his disease.
The petroleum defendants assert that allowing plaintiff to proceed to trial by identification only of exposure to “petroleum-based products” is unfair, because it places them in the position of having to defend each one of the many different petroleum-based products they manufacture, each one containing different levels of benzene and/or PAHs and thus posing varying degrees of health risk. However, the evidentiary record, viewed in the light most favorable to plaintiff, suggests that James was in fact exposed to a wide variety of petroleum-based products from the petroleum defendants, including, among others, gasoline of varying grades, motor oil, and black oil, all of which contained some measure of benzene and/or PAHs. The toxicologist’s report presents considerable scientific evidence of the health risk posed by intense exposure to those chemical compounds. Crediting plaintiffs proofs, the petroleum defendants’ duty to warn presumably extended to most if not all petroleum-based products they shipped in 55-gallon drums.
For summary judgment purposes we must credit the testimony that James was exposed to those products at close proximity on a frequent and regular basis, and that those exposures worked cumulatively to cause James’s cancer. That each of the specific petroleum products to which James was exposed may have contributed to his cancer to a greater or lesser degree than other specific petroleum products cannot become a basis for precluding the liability of the petroleum defendants for failure to warn of the dangers of all of those products. If any defendant’s proofs show
*309
that any of the gasoline and oil residues contained in the drums it had reconditioned at Bessemer could not have caused or exacerbated James’s cancer, then the jury may conclude that plaintiff failed to satisfy her burden of proof with respect to that defendant’s products. If plaintiffs scientific and medical proofs remain uncontroverted, the relative danger of each specific product and the relative intensity of James’s exposure to each specific product would appear to be relevant not to the determination of liability in the first instance, but rather to the apportionment of liability among defendants. See
infra
at 312-313,
Our holding in
Becker, supra,
138
N.J.
at 158-61,
In contrast, plaintiff here alleges that James was exposed to a variety of different petroleum-based products manufactured by the petroleum defendants. Plaintiffs toxicologist’s report indicates that all of those products contain benzene and PAHs, and that any exposure to those chemicals would have contributed, cumulatively, to James’s cancer. Plaintiff is not seeking to impose, and our holding today does not invoke, market-share or alternative theories of liability. See
id.
at 160-62,
Plaintiff’s evidence implicating the chemical defendants is far less developed. The toxicologist’s report focused almost exclusively on benzene and PAHs found in petroleum products. There is little in the deposition testimony and statements of James’s coworkers and Bessemer executives linking any of the chemical defendants to products containing known carcinogens, and limited evidence establishing the intensity of James’s occupational exposure to the products of any of those defendants.
However, with the exception of American Cyanamid Company, plaintiff has not yet engaged in extensive discovery with regard to the manufacturers of non-petroleum-based products and chemicals that supplied either drums for reconditioning or products for use in the reconditioning process. Summary judgment in favor of American Cyanamid Company was affirmed by the court below on
*311
the ground that plaintiff uncovered “no evidence showing that any formaldehyde drums sent by American Cyanamid to Kingsland were ever transferred to Bessemer for reconditioning.”
James, supra,
301
N.J.Super.
at 541,
IV
None of the parties to this action have challenged before this Court the holding of the Appellate Division with regard to
*312
joint and several liability or the burden of apportioning liability among defendants. See
James, supra,
301
N.J.Super.
at 537-39,
The court in
Sholtis, supra,
238
N.J.Super.
at 26-28,
In apportioning fault among the various defendants whose products have been deemed substantial factors in causing James’s cancer such that liability would attach, each defendant may seek to reduce its individual percentage of fault by submitting proof that its products to which James was exposed were less carcinogenic than the other products to which James was exposed, or that James’s exposure to its products was more limited than his exposure to other products. Because the burden of apportioning fault will he with those defendants, if any, found hable for James’s illness and wrongful death, plaintiffs cause of action does not require that she be able to advance proof regarding the relative carcinogenicity of the many specific products to which James was exposed, or of the relative intensity of James’s exposure to any specific product. Plaintiff need only estabhsh medical causation with respect to each defendant in accordance with this opinion. See
supra
at 305-311,
V
In addition to their inclusion in the Law Division’s order granting summary judgment to ah named defendants, Chevron and Texaco filed motions to dismiss plaintiffs complaint pursuant to
R.
4:4-1 and
R.
4:37-2(a) for insufficiency of service of process. Those motions were granted by the court on August 24, 1994. The Law Division, however, granted those motions without prejudice to plaintiff refiling her complaint. The Appellate Division reversed, remanding for an evidentiary hearing to determine “whether in fact Chevron and Texaco were prejudiced by the untimely issuance of the summonses.”
James, supra,
301
N.J.Super.
at 546,
Although plaintiff filed her complaint against Chevron, Texaco and other defendants on February 7, 1992, Chevron was not served with a summons until April 8, 1994, and Texaco not until May 18, 1994. The Law Division initially denied Chevron’s and Texaco’s joint motion to dismiss for untimeliness of service, but indicated that those parties could renew the motion if they could show prejudice because of the loss or destruction of crucial evidence by Bessemer and Kingsland between the date the complaint was filed and the date that process was served. Determining that the corporate records of Bessemer and Kingsland were destroyed after Bessemer and Kingsland ceased operations in approximately June 1992, Chevron and Texaco renewed their motion to dismiss. That motion was then granted by the Law Division, which entered an order dismissing plaintiffs complaint against Chevron and Texaco without prejudice.
Rule 4:4-1 states:
The plaintiff, his attorney or the clerk of the court may issue the summons. If a summons is not issued within 10 days after the filing of the complaint the action may be dismissed in accordance with R. 4:37-2(a). Separate or additional summonses may issue against any defendants.
Rule 4:37-2(a) states:
For failure of the plaintiff to cause a summons to issue within 10 days after filing the complaint or to comply with these rules or any order of court, the court in its discretion may on defendant’s motion dismiss an action or any claim against him. Such a dismissal shall be without prejudice unless otherwise specified in the order.
Although we have stated that “[t]he decision whether to dismiss with or without prejudice is reposed in the sound discretion of the trial court,”
Crispin v. Volkswagenwerk, A.G.,
96
N.J.
336, 346,
Here, plaintiffs complaint appears meritorious, and the failure to make proper service is attributable solely to the neglect of the plaintiffs attorney, not to the plaintiff herself. Therefore, the Law Division should not have dismissed plaintiffs complaint against Chevron and Texaco “in the absence of demonstrable prejudice.”
State v. One 1986 Subaru,
120
N.J.
310, 315,
The problem is that the certifications of Klein and Richard, Bessemer’s president and environmental officer, respectively, relied on by the motion judge, did not indicate the time frame for the documents Bessemer allegedly destroyed. It appears from the certifications that the records were destroyed sometime between June 1992 and January 26,1994. The records destroyed, however, were only for a limited period of time. Klein testified in his deposition that the records destroyed after June 1992 only covered the period beginning in 1990. Thus, there is an open question whether the records destroyed during the delay in service wei’e relevant to the time periods of James’ employment. There is therefore a question whether Chevron and Texaco were really prejudiced by the destruction of those records. In other words, the truly pertinent records may have been destroyed before plaintiff had filed her original complaint in 1992.
[James, supra, 301 N.J.Super. at 545,694 A.2d 270 .]
In view of the uncertainty regarding whether Chevron and Texaco were prejudiced by the untimely service of process, the Appellate Division was correct to remand for an evidentiary hearing. Although an evidentiary hearing on the issue of prejudice is not mandated whenever a complaint is dismissed, “courts have required an evidentiary hearing where the record before the trial court has not provided an adequate basis for a fully informed
*316
determination of the underlying issue____”
Abtrax Pharmaceuticals, Inc. v. Elkins-Sinn, Inc.,
139
N.J.
499, 518-19,
As recognized by the Appellate Division, it is possible that an evidentiary hearing will reveal that records going to the heart of the “frequency, regularity and proximity” test were destroyed between the date plaintiff filed her complaint and the dates Chevron and Texaco were served with summonses.
James, supra,
301
N.J.Super.
at 545,
VI
The judgment of the Appellate Division is affirmed. We remand this action to the Law Division for further proceedings consistent with this opinion and with the opinion of the Appellate Division.
For affirmance and remandment — Chief Justice PORITZ, and Justices HANDLER, POLLOCK, O’HERN, STEIN, and COLEMAN — 6.
Opposed — None.
Notes
Although the Appellate Division opinion did not address the question whether summary judgment was properly granted in favor of Ashland, Occidental and Pride, those defendants remain in this action and joined the petition for certification seeking this Court’s reversal of the Appellate Division's decision. Named-defendant Linde Gases was dismissed by stipulation of the parties in July 1995. Named-defendants Roman Heart and Baker Lite Company are not referred to in the record before the Court, and we presume they are no longer parties to this action. Pope Chemical, named separately in the complaint, is in fact a predecessor of Daicolor-Pope, Inc. rather than a separate entity. Daicolor-Pope, Inc. did not join the other defendants that petitioned for certification and thus is not a party to this appeal, although our disposition undoubtedly will affect its posture on remand.
We assume, for purposes of this appeal from summary judgment, that the opinions of plaintiff's scientific and medical experts will be deemed admissible in a pre-trial hearing pursuant to
N.J.R.E.
104. For a discussion of the bases for admission of scientific and medical evidence in toxic-tort actions, see
Landrigan, supra,
127
N.J.
404,
In environmental tort actions where it is possible for the trier of fact to apportion negligence or fault pursuant to N.J.S.A. 2A: 15-5.2, the percentage of compensatory damages that the plaintiff may recover from each tortfeasor is governed by N.J.S.A. 2A:15-5.3d(2) and (3).