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. e du/thir dc ir c uit_1997/243Filed October 17, 1997

UNITED STATES COURT OF APPEALS

FOR THE THIRD CIRCUIT

No. 96

- 5818

CHARLES KANNANKERIL; MARY KANNANKERIL,

individually and as next friend of Charlene and

Crystal Kannankeril; CHARLENE KANNANKERIL;

CRYSTAL KANNANKERIL

v.

TERMINIX INTERNATIONAL, INC.; TM SPECIAL

PARTNERS, INC.; TERMINIX MGP, INC., General Partners

of the Terminix International Company Limited

Partnership; TERMINIX INTERNATIONAL; DOW

CHEMICAL U.S.A.; WHITMIRE RESEARCH

LABORATORIES, INC.; FORD CHEMIC AL & SERVICE,

INC.; DENNIS BUTTIMORE, c/o Terminix International;

THE TERMINIX INTERNATIONAL COMPANY

LIMITED PARTNERSHIP

Mary Kannankeril, Individually and as

Next Friend of Charlene Kannankeril,

Appellant.

On Appeal from the District Court

for the District of New Jersey

(D.C. Civil Action No. 92

- cv

- 03150)

Argued on July 17, 1997

Before: SLOVITER, Chief Judge, ROTH and

MICHEL,1 Circuit Judges

_________________________________________________________________

1. Honorable Paul R. Michel, United States Court of Appeals for the

Federal Circuit, sitting by designation.

(Opinion filed October 17, 1997)

Evan T. Lawson, Esq. (Argued)

Christopher N. Cook, Esq.

Lawson & Weitzen

425 Summer Street

Boston, MA 02210Attorneys for Appellants

Kevin E. Wolff, Esq. (Argued)

Robert W. Muilenburg, Esq.

McElroy, Deutsch & Mulvaney

1300 Mount Kemble Avenue

P.O. Box 2075

M orristown, NJ 07962

- 2075

Attorneys for Appellee Terminix

International

OPINION OF THE COURT

ROTH, Circuit Judge.

The Kannankerils, Dr. Mary Kannankeril, her husband,

Charles, and their children, Charlene and Crystal, sued a

p est exterminator, the Terminix International Company L.P.

("Terminix"), seeking damages for injuries allegedly arising

out of the application of pesticides to their residence. The

district court found the opinion of Dr. Benjamin Gerson,

the medical exp ert of Dr. Mary Kannankeril, to be

unreliable and unsupported by facts. Having excluded Dr.

Gerson's opinion, the district court held that Dr.

Kannankeril had failed to produce any evidence that her

cognitive impairment had been caused by exposure to

pesticides applied by Terminix. The court granted summary

judgment in favor of Terminix. The admissibility of Dr.

Gerson's opinion is the sole issue on which the

Kannankerils have appealed. They argue that the district

court erroneously excluded the te stimony of Dr. Gerson.

We conclude that the district court improperly exercised

its gatekeeping role by excluding Dr. Gerson's testimony.

2

Accordingly, we will vacate that portion of the order of the

district court, granting summary judgment against Dr.

Mary Kannankeril on this point, and we will remand this

case for further proceedings consistent with this opinion.2

I. BACKGROUND

The Kannankerils entered into a one

- year contract with

Terminix on May 30, 1989, for the control of carpenter ants

through the application of pesticides to certain interior

portions and the outside deck of the Kannankerils'

residence. From May 31, 1989, through October 5, 1990,

Terminix treated the Kannankeril residence o n at least

twenty occasions at intervals ranging from once a month totwice in a three day period. Terminix applied pesticides,

containing Dursban, until the Kannankerils canceled the

service on October 5, 1990.

Dursban, the active ingredient in cer tain pesticides used

by Terminix, is a formulation of chlorpyrifos, an

organophosphate poison. The organophosphates kill insects

by inhibiting the normal breakdown of acetylcholine, which

functions as a neurotransmitter in several life forms,

includin g humans. The Kannankerils argue that despite the

well

- known chronic effects of chlorpyrifos, Dursban was

sprayed excessively and improperly in their home. For

example, Dursban was sprayed on the cooking range,

around the dishwasher, and on the baseboa rd heater.

Dursban was also sprayed in cupboards where pots and

pans were stored. Terminix, however, claims that any liquid

pesticide that was applied consisted almost entirely of

water, with minute concentrations of liquid pesticide added

to make the final active solution.

The Kannankerils' suit against Terminix involved alleged

injury to Dr. Mary Kannankeril, a former Medical Director

of Psychiatric Emergency Services at Saint Mary's Hospital

in Passaic, New Jersey. Dr. Kannankeril claims to su ffer

wide

- ranging physiological and cognitive symptoms from

_________________________________________________________________

2. Our decision, vacating the summary judgment against Dr.

Kannankeril, is without prejudice to any motion for summary judgm ent

on other grounds which Terminix may bring.

3

exposure to the pesticides, including Dursban, applied by

Terminix.3 The symptoms first appeared in August 1990,

over one year after Terminix began its service. T he

Kannankerils did not relate Dr. Kannankeril's symptoms

with Terminix's ongoing pesticide applications until October

1990. After the entire family developed a rash, the

Kannankerils began to suspect Dursban as the cause of

their problems. When the K annankerils complained of a

strong odor in their home after the last application,

Terminix sent Service Master to clean the Kannankerils'

residence. In July 1991, nine months after the last

application of pesticide, the Kannankerils requested that

the New Jersey Department of Environmental Protection

("DEP") test their residence for the existence of pesticides.

The DEP collected air samples from the residence on July

10, 1991. An analysis of the samples indicated non

detectable levels of pesticide s.

Dr. Kannankeril allegedly developed chronic toxicityrelated to exposure to chlorpyrifos and became sensitized to

multiple other chemicals so that further exposure to

organophosphates would result in disabling physical

problems. As a result of he r ill health, she gave up her

hospital position in March, 1993, and now sees patients

only in an office at home.

Plaintiffs named Dr. Benjamin Gerson, M.D., to testify as

a medical expert to establish that exposure to Dursban

caused Dr. Kannankeril' s injury.4 Dr. Gerson provided the

following opinion:

_________________________________________________________________

3. Only the causation of Dr. Kannankeril's cognitive impairment remains

an issue in the case. These cognitive deficits include mem ory loss,

concentration loss, sleeplessness, general anxiety, and headaches. Her

other alleged physical symptoms included insomnia, numbness, muscle

twitching, pain in muscles and joints, vaginal bleeding, urinary

incontinence, nausea, skin rashes, and depigmentation patches

throughout her body.

4. Dr. Gerson's qualifications included: Physician certified by the

American Board of Toxicology and the American Board of Pathology;

Director of the Boston University School of Medicine's Laboratory of

A nalytical Toxicology and Director of the Research Data Worldwide

Clinical Laboratory; Consultant to the Food and Drug Administration's

4

The temporal relationship and the nature of her

complaints le ad me to conclude that with reasonable

medical certainty, the cause of Dr. Kannankeril's

Central Nervous System manifestations of toxicity is

exposure to Dursban in 1989 to 1990.

App. at 51.5 Dr. Gerson is the only medical expert proffered

by the Kannankerils on causation and his opinion is limited

to the causation of Dr. Kannankeril's cognitive impairment.

His findings are based on Dr. Kannankeril's account of her

cognitive symptoms and on a report prepared by Dr. Ellen

Grob er, a neuropsychologist who examined Dr.

Kannankeril. Dr. Gerson also relied on a summary report of

the times and amounts of Dursban applications to the

Kannankeril home as well as on his general experience and

readings, general medical knowledge, stan dard textbooks,

and standard references.

II. STANDARD OF REVIEW

A district court's ruling on admissibility of expert

testimony is reviewed for abuse of discretion. Government of

the Virgin Islands v. Sanes, 57 F.3d 338, 341 (3d Cir.1995); In re Paoli R.R. Yard PCB Litig., 35 F.3d 717, 749 (3d

Cir. 1994). To the extent that the district court's ruling

turns on interpretation of the Federal Rules of Evidence,

_________________________________________________________________

Center for Devices and Radiological Health; Professor of Pathology and a

Professor of Pharmacology & Experimental Therapeutics at Boston

University; Instructor in Pathology, Harvard Medical School; Special

Lecturer in Clinical Laboratory Science, Northeastern University;

Assistant Professor of Pathology, Harvard Medical School; Associate

Professor of Pathology, Harvard Medical School; Director of Clinical

Chemistry and Toxicology at Veterans Affairs Medical Center in Boston,

Massachusetts.

5. Under New Jersey law, medical expert testimony must be made with

a reasonable degree of certainty. See Bondi v. Pole, 246 N.J. Super. 236

(App. Div. 1991); Vuocolo v. Diamond Shamrock Chemical Co., 240 N.J.

Super. 289 (App.Div. 1990); Johnesee v. The Stop & Shop Companies,

174 N.J. Super. 426 (App.Div. 1980). New Jersey's rule should govern in

the present case since it is a substantive law that is part of the

appellants' burden of proof. See In re Paoli R.R. Yard PCB Litig., 35 F.3d

717, 752 (3d Cir. 1994).

5

our review is plenary. United States v. Velasquez, 64 F.3d

844, 848 (3d Cir. 1995); Paoli, 35 F.3d at 749. We review

the district court's findings of fact under a clearly

erroneous standard. Velasquez, 64 F.3d at 848.

II I. DISCUSSION

A. Standard of Admissibility for Expert Testimony

Under the Federal Rules of Evidence, it is the role of the

trial judge to act as a "gatekeeper" to ensure that any and

all expert testimony or evidence is not only relevant, but

also reliable. Daubert v. Merrell Dow Pharmaceuticals, Inc.,

509 U.S. 579, 589. (1993). The Rules of Evidence embody

a strong and undeniable preference for admitting any

evidence which has the potential for assisting the trier of

fact. See Holbrook v. Lykes Bros. S.S. Co., 80 F.3d 777, 780

(3d Cir. 1996). Rule 702, which governs the admissibility of

expert testimony, has a liberal policy of admissibility. See

Holbrook, 80 F.3d at 780; Paoli, 35 F.3d at 741.

Rule 702 has three major requirements: (1) th e proffered

witness must be an expert; (2) the expert must testify about

matters requiring scientific, technical or specialized

knowledge; and (3) the expert's testimony must assist the

trier of fact. See Paoli, 35 F.3d at 741

- 42. The issue of this

ap peal involves the second requirement of the expert'stestimony. In interpreting this second requirement, we have

concluded that "an expert's testimony is admissible so long

as the process or technique the expert used in formulating

the opinion is relia ble." Id. at 742 (citing Daubert, 113 S.Ct.

at 2794

- 95). In order for the expert testimony to be

"reliable," we have required that the testimony be based on

the "methods and procedures of science," rather than on

"subjective belief or unsupported specu lation." Paoli, 35

F.3d at 744. Moreover, Daubert does not set up a test of

which opinion has the best foundation, but rather whether

any particular opinion is based on valid reasoning and

reliable methodology. Admissibility decisions focus on the

exp ert's methods and reasoning; credibility decisions arise

after admissibility has been determined. See Paoli, 35 F.3d

at 743

- 46.

6

There are several factors that a district court should take

into account in evalu ating whether a particular scientific

methodology is reliable. See Paoli, 35 F.3d at 742.6

Although these factors are neither exhaustive nor

applicable in every case, they provide a convenient starting

point for analyzing the opinion of Dr. Gerson. Our inquiry

focuses on principles and methodology and not on the

conclusions they generate. Id. at 744. The analysis of the

conclusions themselves is for the trier of fact when the

expert is subjected to cross

- examination. Id. The

Kannankerils needed to demonstrate by a preponderance of

evidence only that Dr. Gerson's opinion was based on "good

grounds." Id.

B. Reliability of Dr. Gerson's Testimony

The district court refused to admit Dr. Gerson's

testimony because of insufficient factual foundati on to

prove that the cause of Dr. Kannankeril's cognitive

impairment was exposure to Dursban. We conclude,

however, that Dr. Gerson's opinion meets the requirements

for the admission of expert testimony under Rule 702 of the

Federal Rules of Evidence, as set forth in Daubert and

interpreted by us in Paoli.

1. Differential Diagnosis

In its opposition to Dr. Gerson's testimony, Terminix has

_________________________________________________________________

6. These nonexclusive guidelines, draw n from Daubert and this Court's

opinion in United States v. Downing, 753 F.2d 1223 (3d Cir. 1985),

include:(1) whether a method consists of a testable hypothesis; (2) whether

the method has been subject to peer review; (3) the known or

potential rate of error; (4) the existence and maintenance of

standards controlling the technique's operation; (5) whether the

method is generally accepted; (6) the relationship of the technique

to

methods which have been e stablished to be reliable; (7) the

qualifications of the expert witness testifying based on the

methodology; and (8) the non

- judicial uses to which the method has

been put.

Paoli, 35 F.3d at 742 n.8.

7

emphasized that Dr. Gerson did not himself perform any

diagnostic medical tests. Terminix argues that Dr. Gerson

did not employ sufficient diagnostic techniques to have

good grounds for his conclusions or to have properly

performed a dif ferential diagnosis. We have recognized

"differential diagnosis" as a technique that involves

assessing causation with respect to a particular individual.

Paoli, 35 F.3d at 758. Differential diagnosis is defined for

physicians as "the determination of which of two or more

diseases with similar symptoms is the one from which the

patient is suffering, by a systematic comparison and

contrasting of the clinical findings." STEDMAN'S MEDICAL

DICTIONARY 428 (25th ed. 1990). The elements of a

differential diagnosis may consist of the performance of

physical examinations, the taking of medical histories, and

the review of clinical tests, including laboratory tests. A

doctor does not have to employ all of these techniques in

order for the doctor's diagnos is to be reliable. See Paoli, 35

F.3d at 759. A differential diagnosis may be reliable with

less than all the types of information set out above. See id.

Indeed, as we held in Paoli, "to the extent that the district

court concluded otherwise [i.e., tha t a differential diagnosis

made on less than all types of information cannot be

reliable], we hold that it abused its discretion." Id.

Depending on the medical condition at issue and on the

clinical information already available, a physician may

rea ch a reliable differential diagnosis without himself

performing a physical examination, particularly if there are

other examination results available. In fact, it is perfectly

acceptable, in arriving at a diagnosis, for a physician to rely

on examinati ons and tests performed by other medical

practitioners.

These principles are applicable to the admissibility of

Dr. Gerson's expert opinion regarding Dr. Kannankeril. The

district court found that Dr. Gerson never performed anyclinical tests to sup port his opinion of causation. Dr.

Gerson did not "examine, or even speak to" Dr.

Kannankeril. Instead, Dr. Gerson reviewed the records of

Dr. Kannankeril's medical history. Dr. Gerson also relied on

Dr. Grober's report of Dr. Kannankeril's neuropsycho logical

complaints and of her cognitive impairment. Terminix does

8

not claim that the medical records relied upon by Dr.

Gerson were incomplete or inaccurate. As noted by this

Court in Paoli, "evaluation of the patient's medical records

is a reliable method of concluding that a patient is ill even

in the absence of a physical examination." Id. at 762. A

doctor needs only one reliable source of information

showing that a plaintiff is ill; either a physical te st or

medical records will suffice for this. Id. at 762. For these

reasons, the reliability of Dr. Gerson's opinion is not

necessarily diminished by the fact that he himself did not

perform a physical examination.

Moreover, in making his evaluation, Dr. Gerson was

aware that one test, the cholinesterase blood test, did not

produce abnormal results. The district court noted that the

blood test for cholinesterase levels is "the most accepted

test method for determining exposure to Dursban."

Howeve r, the cholinesterase test result is but one of the

factors considered by Dr. Gerson. Despite the negative

results from this test, Dr. Gerson still opined that, as a

matter of reasonable medical certainty, Dursban had

caused Dr. Kannankeril's cognitive impairment. It is for the

jury to decide whether a single cholinesterase test, yielding

results within normal limits, outweighs the other factors

relied upon by Dr. Gerson and undermines his opinion.

This is an issue of credibility, not of admissibili ty.

Furthermore, we do not agree with the trial court's

finding that "every" objective medical test showed normal

results. The cholinesterase test was not the only clinical

test performed on Dr. Kannankeril. Dr. Grober, the

neuropsychologist at the Albert Einstein Medical Center,

confirmed a diminution in Dr. Kannankeril's cognitive

abilities.

In attacking the differential diagnosis performed by the

plaintiff's expert, the defendant may point to a plausible

cause of the plaintiff's illness oth er than the defendant's

actions. It then becomes necessary for the plaintiff's expert

to offer a good explanation as to why his or her conclusion

remains reliable. Paoli, 35 F.3d at 762. Dr. Gerson,

however, was never challenged by the presentation of

alternate diagnoses by other physicians. Moreover,Terminix, in challenging Dr. Gerson's opinion, has not

9

raised any other theory of causation for Dr. Kannankeril's

cognitive impairment.7 The record in this ca se is devoid of

any alternate diagnosis which Dr. Gerson ignored or failed

to consider.

Furthermore, we reject Terminix's argument that Dr.

Gerson admitted to alternate causes other than exposure to

Dursban for Dr. Kannankeril's condition. Dr. Gerso n had

testified at his deposition that something other than

exposure to organophosphates "could" have caused each of

the individual symptoms displayed by Dr. Kannankeril.

While, however, an alternate explanation for each of Dr.

Kannankeril's individua l symptoms may exist separately,

Dr. Gerson concluded with reasonable medical certainty

that Dursban was the most likely cause of her condition as

a whole. Terminix's exploration of the cause of each

individual symptom goes not to the admissibility of the

evidence but to its weight.

2. Degree of Exposure

The Kannankerils also contend that the district erred in

finding that Dr. Gerson had no knowledge of Dr.

Kannankeril's degree of exposure to Dursban. According to

the district court, Dr. Gerso n did not know the levels of

Dursban at the Kannankerils' home at the time of

exposure, and he did not know the amount of time

plaintiffs spent in the home. We conclude, however, that

the district court erred when it failed to recognize that Dr.

Gerso n had sufficient knowledge of exposure from his

review of Terminix's application records, showing when,

how much, and where pesticide had been applied.

Terminix asserts, however, that these application records

are "unreliable as a matter of law as a tool" to determine

Dr. Kannankeril's exposure. The trial court agreed and

ruled that the only information reviewed by Dr. Gerson

which addressed actual levels of pesticides in the

_________________________________________________________________

7. Terminix had, of course, no obligation to present an alternate theory

of causation in its effort to have Dr. Gerson's opinion excluded. However,

in determining whether a proper differential diagnosis was conducted, a

consideration of other diagnoses may be relevant.

10Kannankeril home was the analysis performed by the DEP

in July 1991, nine months after the last application of

Dursban. The results of that sampling indicated non

detectable levels of pesticide s.

We find that Terminix's assertion is without merit. First,

there is no expert opinion in the record to establish that an

ambient air test, particularly an ambient air test performed

nine months after the final application of Dursban, is the

only appropriate way in this case to gauge exposure to the

organophosphate. Moreover, the plaintiffs were prepared to

offer into evidence the Dursban product label which

contained warnings such as: "HARMFUL IF SWALLOWED .

HARMFUL IF ABSORBED THROUGH SKIN . CAUSES EYE

AND SKIN IRRITATION" and "Throughly wash dishes and

food handling utensils with soap and water if they become

contaminated by application of this product. Do not allow

children or pets to contact treated surfaces until spray has

dried." App . at 241

- 43. Under the facts as presented in this

case, the district judge erred in ruling that an expert may

rely only on the ambient air test to determine whether Dr.

Kannankeril had been exposed to Dursban. Instead, all

factual evidence of the prese nce of the chemicals in the

residence should be relevant in forming an expert opinion

of causation.

We conclude that it is for the trier of fact to determine

what weight to give the ambient air test results as an

indication of exposure. See Joiner v . General Elec. Co., 78

F.3d 524, 534 (11th Cir. 1996) (reversing exclusion of

expert opinions that plaintiffs' exposure to certain

chemicals caused his lung cancer where there were issues

of fact whether plaintiff was actually exposed to the

chemical s so that summary judgment based on a finding of

no exposure was inappropriate). The issue whether an

ambient air test should be given more weight than pesticide

application records goes to the weight rather than the

admissibility of evidence. See Unit ed States v. Velasquez, 64

F.3d 844, 848 (3d Cir. 1995) (citing United States v.

Jakobetz, 955 F.2d 786, 800 (2d Cir. 1992)). The trial judge

must be careful not to mistake credibility questions for

admissibility questions.

11

3. Peer Review and Publication

Two other factors that a district court can take into

account in assessing reliability are peer

- review and

publication. They may not, however, in every case be

necessary conditions of reliability. See D aubert, 509 U.S. at593; Paoli, 35 F.3d at 742. In the instant case, Dr. Gerson

admitted that he has not produced any publication on

organophosphates. Because the toxic effects of

organophosphates on humans are well recognized by the

scientific commun ity, however, Dr. Gerson's opinion is not

a novel scientific theory regarding organophosphates.8

Instead, Dr. Gerson merely reported that Dr. Kannankeril

exhibited the "signs and symptoms of chronic toxicity

related to exposure to chlorpyrifos (Dursban )." Thus,

although Dr. Gerson did not write on the topic, his opinion

is supported by widely accepted scientific knowledge of the

harmful nature of organophosphates. See also McCullock v.

H.B. Fuller Co., 61 F.3d 1038, 1042 (2d Cir. 1995) (holding

tha t peer review and publication or general acceptance of

an expert's theory goes to the weight of the testimony

rather than its admissibility).

Based on the record before us, we conclude that

Dr. Gerson's opinion on causation has a factual basis

and s upporting scientific theory. Dr. Gerson based his

opinion on Dr. Kannankeril's medical records, Dr. Grober's

reports confirming her medical condition, and Terminix's

application receipts. He also relied on general experience

and readings, general medic al knowledge, standard

textbooks, and standard references. After considering all

the relevant facts, Dr. Gerson reported that "[t]he temporal

relationship and the nature of her complaints lead

me to conclude that with reasonable medical certainty, the

cause of Dr. Kannankeril's Central Nervous System

manifestations of toxicity is exposure to Dursban in 1989 to

1990." App. at 51. Dr. Gerson's testimony is neither

conjecture nor speculation. His opinion was clearly stated

to a reasonable degree of me dical certainty.

_________________________________________________________________

8. It is an acknowledged scientific fact that chlorpyrifos, the active

ingredient in Dursban, is harmful to humans and can cause the very

symptoms displayed by Dr. Kan nankeril.

12

Whether the appellants' expert might have done a better

job is not the test. We have stated that "it is an abuse of

discretion to exclude testimony simply because the trial

court does not deem the p roposed expert to be the best

qualified or because the proposed expert does not have the

specialization that the court considers most appropriate."

Holbrook, 80 F.3d at 782. If the expert meets liberal

minimum qualifications, then the level of the expe rt's

expertise goes to credibility and weight, not admissibility.

See Paoli, 35 F.3d at 741. The Second Circuit addressed a

similar issue and commented that the expert's allegedshortcomings were raised properly on cross

- examination

and went to the cr edibility, not the admissibility, of his

testimony. McCullock, 61 F.3d 1038, 1043 (2d Cir. 1995).

Consequently, we reject Terminix's suggestion that Dr.

Gerson must be a specialist in Dursban to provide expert

testimony on the causation of Dr. Kannanke ril's injury.

The Kannankerils' burden is only to provide an expert

opinion that is relevant and reliable and that will assist the

trier of fact. As we have repeated above, issues of credibility

arise after the determination of admissibility. Credibi lity is

for the jury. We conclude that, under the facts presented

here, the district court erred in ruling that Dr. Gerson's

expert testimony on causation was inadmissible.

IV. CONCLUSION

For the foregoing reasons, we hold that the district court

erred as a matter of law in refusing to permit Dr. Gerson to

testify as to his opinion of the causation of Dr.

Kannankeril's illness. Accordingly, we will vacate that

portion of the district court order which granted summary

judgment against Dr. Mary Kannankeril, and we will

remand this case for further proceedings consistent with

this opinion.

A True Copy:

Teste:

Clerk of the United States Court of Appeals

for the Third Circuit

13