Amicus Curiae Brief — Monsanto Company, Petitioner v. John L. Durnell

No. 24-1068

IN THE

Supreme Court of the United States

__________

MONSANTO COMPANY,

Petitioner,

v.

JOHN L. DURNELL,

Respondent.

_____________

On Writ of Certiorari

to the Missouri Court of Appeals

_____________

BRIEF OF PHILIP LANDRIGAN, MD, MSC,

LIANNE SHEPPARD, PHD, CHRISTOPHER

PORTIER, PHD, DENNIS WEISENBURGER,

MD, AND BRUCE P. LANPHEAR, MD, MPH

AS AMICI CURIAE

IN SUPPORT OF RESPONDENT

_____________

ALANI GOLANSKI

Counsel of Record

ROBIN L. GREENWALD

ALICIA BUTLER

ROBERT QUIGLEY

WEITZ & LUXENBERG P.C.

700 Broadway

New York, NY 10003

(212) 558-5500

April 1, 2026

DAVID WOOL

WOOL TRIAL LAW LLC

1001 Bannock Street

Suite 410

Denver, CO 80204

(720) 370-6576

TABLE OF CONTENTS

Table of Authorities .................................................. iii

INTEREST OF AMICI CURIAE .............................. 1

INTRODUCTION AND SUMMARY OF

ARGUMENT .............................................................. 4

STATEMENT ............................................................ 7

A.

Statutory and Regulatory Background ........... 7

B.

Scientific and Factual Background ............... 11

ARGUMENT ............................................................ 12

I.

Overwhelming Evidence Establishes that

Glyphosate and Glyphosate-Based Herbicides

Cause Cancer. ................................................ 12

II. Granting Immunity from Label-Based Tort

Liability Would Incentivize the Type of

Deceit Monsanto Exhibited in Relation to

Roundup ......................................................... 19

A. The IBT Scandal ....................................... 20

B. Continued Manipulation of Carcinogenicity

Data: The Magic Tumor ........................... 26

C. Suppression of Expert Information

Relating to Roundup’s Genotoxicity ......... 27

D. The Dermal Penetration Study Coverup . 30

III. IARC’s 2015 Findings Linking Glyphosate

with Cancer Have Ample Scientific Support,

Notwithstanding Petitioner and Its Amici’s

Criticisms ....................................................... 31

ii

IV. The Scientific Evidence Linking Glyphosate

with Cancer Goes Far Beyond IARC’s Analysis

and Has Only Become Stronger Over Time. . 34

CONCLUSION ........................................................ 37

iii

TABLE OF AUTHORITIES

Pages

Cases

Bates v. Dow Agrosciences L.L.C.,

544 U.S. 431, 125 S. Ct. 1788 (2005) ........ 5, 6, 7, 36

In re Roundup Products Liability Litigation,

390 F. Supp. 3d 1102 (N.D. Cal. 2018) ................. 34

Natural Resources Defense Council v. EPA,

38 F. 4th 34 (9th Cir. 2022) .................................. 32

Pilliod v. Monsanto Company,

282 Cal.Rptr.3d 679 (Cal. App. 1 Dist., 2021) ...... 21

United States v. Keplinger,

776 F.2d 678 (1985), cert. denied., 476 U.S. 1183

(1986) ..................................................................... 21

Wyeth v. Levine,

555 U.S. 555 (2009) ................................................. 7

Statutes and Regulations

15 U.S.C. § 2601 et seq ................................................ 8

21 U.S.C. § 301 et seq .................................................. 7

21 U.S.C. 346a(b)(2)(B)(ii)–(iv) ................................. 10

40 C.F.R. § 155.50(b)................................................. 10

40 C.F.R. § 159.167 ................................................... 30

40 C.F.R. § 159.184(a), (b) .......................................... 6

40 C.F.R. pt. 159 ....................................................... 10

62 Fed. Reg. 17723 .................................................... 25

7 U.S.C. § 136(a)e(1) ................................................... 9

iv

7 U.S.C. § 136(q)(1)(G) ................................................ 7

7 U.S.C. § 136a(g) ..................................................... 10

7 U.S.C. § 136d(a)(2) ................................................. 10

7 U.S.C. § 136j(a)(1)(E) ............................................... 6

Pub. L. No. 104-170, 110 Stat. 1489........................... 9

Rules

Sup. Ct. R. 37.6 ........................................................... 1

INTEREST OF AMICI CURIAE1

Amicus Philip Landrigan, MD, MSc, is a

pediatrician and epidemiologist. He served as faculty

of the Mount Sinai School of Medicine from 1985–

2018, as Chair of the Department of Preventive

Medicine from 1995–2015, and as Dean for Global

Health beginning in 2010. Since July 2018, Dr.

Landrigan has been the director of programs for

Global Health and the Common Good at Boston

College. His research in the 1970s is credited for

making the association between childhood brain

damage and lead exposure. That research, among

other significant findings, was the first to show that

lead can cause brain damage to children at levels too

low to cause clinically evident signs and symptoms –

a phenomenon now termed “subclinical toxicity.” That

research lent support to EPA’s decision to remove lead

from gasoline and paint, resulting in a 95% reduction

of lead poisoning among US children. His research

also includes a 1993 National Academy of Science

report on Pesticides in the Diets of Infants and

Children that provided the blueprint for the Food

Quality

Protection

Act,

the

only

federal

environmental law that explicitly protects children’s

health. Dr. Landrigan was also involved in the

medical and epidemiological studies following the

World Trade Center attacks and resulting injuries

from exposure to the destruction.

1 Pursuant to Rule 37.6, counsel for amici curiae are the sole

authors of this brief. Counsel for amici disclose that they are

counsel for Plaintiffs in other Roundup litigation. No person or

entity, including amici curiae, made a monetary contribution to

the preparation or submission of the brief.

2

Amicus Lianne Sheppard, PhD, is a biostatistician

focused

on

environmental

exposures

and

epidemiology. She has been a member of the

University of Washington School of Public Health

faculty since 1993, with appointments in two

departments: Biostatistics, and Environmental and

Occupational Health Sciences, where she served as

Interim Chair from 2024–2025. Her research

addresses the health effects of environmental and

occupational exposures with particular attention to

the impact of exposure assessment and modeling on

understanding and making inference about health

impacts. A Fellow of the American Statistical

Association, Dr. Sheppard has served the U.S.

Environmental Protection Agency (EPA) as a special

government employee in multiple capacities, most

recently as Chair of the Clean Air Scientific Advisory

Committee from 2021–2014. In 2016–2017 she served

as a member of the EPA Federal Insecticide,

Rodenticide, and Fungicide Act Scientific Advisory

Panel for Evaluation of the Carcinogenic Potential of

Glyphosate. This led her to publish several follow-on

glyphosate-related research papers. In 2020, Dr.

Sheppard received the ISEE Research Integrity

Award,2 established to honor individuals working in

the field of environmental epidemiology who have

demonstrated exceptional integrity in the face of

pressure from special interests. Dr. Sheppard has

been the Rohm & Haas Endowed Professor in Public

Health Sciences since 2021.

Amicus

Christopher

Portier,

PhD,

is

a

biostatistician. His PhD thesis addressed the optimal

design for a two-year rodent carcinogenicity study.

2 See https://www.youtube.com/watch?v=8sPG8IsBv6Q.

3

Post-PhD, he had a joint appointment at the National

Institute of Environmental Health Sciences and the

National Toxicology Program (NIEHS/NTP) designing

and analyzing toxicology experiments. Five years

later, he developed his own research group that

became the Laboratory of Computational Biology and

Risk Assessment, focused on application of

computational tools to identify chemicals toxic to

humans. In 2006, Dr. Portier became the Associate

Director of the NIEHS, and in 2010 the Director of the

National Center for Environmental Health at the

Centers for Disease Control and Prevention, while

also serving as Director of the Agency for Toxic

Substances and Disease Registry, where he was

responsible for determining risks at toxic waste sites

and EPA-designed clean-up. He also served from

2005–2010 as Chair of the Subcommittee on Toxics

and Risk of the President’s National Science and

Technology Council, and from 1998–2003, Chair of

EPA’s Science Advisory Panel, focused on advising the

pesticides program. He has also served as an expert

witness for plaintiffs in Roundup litigation.

Amicus Dennis Weisenburger, MD, is a physician

and pathologist specializing in the study of

hematopoietic and immune systems diseases, with a

specialty in non-Hodgkin lymphoma (NHL). From

1984–2012, he was a faculty member in the

Department of Pathology and Microbiology at the

University of Nebraska Medical Center, and was also

the chief pathologist for the Nebraska Lymphoma

Study Group. He collaborated with the National

Cancer Institute (NCI) in a large epidemiologic study

of NHL and related disorders in Eastern Nebraska. In

2012, Dr. Weisenburger became Chairman of the

Department of Pathology at City of Hope National

4

Medical Center, an NCI-designated comprehensive

cancer center. He has published over 300 peerreviewed papers on NHL. He has also served as an

expert witness for plaintiffs in Roundup litigation.

Amicus Bruce P. Lanphear, MD, MPH, is a

physician specializing in preventive medicine and a

professor in the Faculty of Health Sciences at Simon

Fraser University in Vancouver, British Columbia.

For over 30 years, he has conducted research on the

health effects of environmental toxicants, with a focus

on children’s health and disease prevention. His work

has informed federal standards for lead in air, water,

and house dust and helped establish the now widely

accepted conclusion that there is no safe level of lead

exposure for children. Dr. Lanphear has served in key

scientific advisory roles shaping environmental health

policy in North America as a member of the

Commission

for

Environmental

Cooperation’s

Children’s Health Expert Panel, on multiple EPA

Science Advisory Boards, and as co-chair of Health

Canada’s Pest Management Regulatory Agency

Science Advisory Committee on pest control products.

He has also advised the Centers for Disease Control

and Prevention, Health Canada, and other

governmental bodies on environmental health

standards and risk assessment.

INTRODUCTION AND

SUMMARY OF ARGUMENT

Amici are among the many scientists, physicians,

and public health professionals who have concluded

that scientific evidence establishes that glyphosate

and glyphosate-based herbicides (GBHs) cause cancer

and other health effects in humans. This strong

5

scientific evidence matters deeply to the question now

before this Court. Petitioner and its supporting amici

inaccurately frame this as a case in which federal

preemption is both legally required and prudentially

necessary, because EPA made definitive scientific

findings that glyphosate is not carcinogenic, and the

jury that decided Mr. Durnell’s case was misled by

“junk science.”3

Not so. EPA’s review of glyphosate was narrow and

incomplete, like all reviews that regulators perform at

the pesticide registration stage. EPA’s review was

further hindered by Monsanto’s decades-long

suppression of adverse scientific evidence about

Roundup’s

carcinogenicity.

Meanwhile,

epidemiological evidence, human studies, animal

studies, and genetic testing have only strengthened

the conclusion that glyphosate is linked to an

increased risk of non-Hodgkin lymphoma (NHL) – the

cancer of the lymphatic system that Mr. Durnell

developed. Glyphosate is also linked to multiple

additional adverse health effects, including kidney

and liver diseases, and harms to the reproductive,

endocrine, neurological, and other metabolic systems.

Children, infants, and fetuses are the most

susceptible.

This empirical evidence further confirms that the

regulatory review scheme contemplated by FIFRA

and conducted in practice is a narrow one. In Bates,

the Court observed that “FIFRA contemplates that

pesticide labels will evolve over time, as

manufacturers gain more information about their

3 Brief of Amici Curiae Agricultural Retailers Association and

National Agricultural Aviation Association at 2.

6

products’ performance in diverse settings.”4 This

evolution is a consequence of the toxic nature of

pesticides and the limited review regulators perform

at the time of registration. Pesticides are poisons

designed to kill living things, and they lack any direct

benefit to human health. Put another way, being

exposed to pesticides never improved someone’s

health or cured their disease. Accordingly, and unlike

pharmaceutical drugs which undergo multiple rounds

of human clinical trials before they are brought to

market and are designed to save lives and improve

health, pesticides can never be ethically tested on

human beings prior to sale. This means that

functionally, direct evidence of a pesticide’s adverse

effects on human health will generally only surface

after the pesticide is registered and brought to market.

Because of this, Congress imposed upon registrants

“a continuing obligation to adhere to FIFRA’s labeling

requirements,”5 as well as “a duty to report incidents

involving a pesticide’s toxic effects that may not be

adequately reflected in its label’s warnings.”6 And, as

the Court recognized in Bates, “[p]rivate remedies that

enforce federal misbranding requirements would

seem to aid, rather than hinder, the functioning of

FIFRA.”7 Moreover, “in all preemption cases, and

particularly in those in which Congress has legislated

in a field which the States have traditionally occupied,

we start with the assumption that the historic police

powers of the States were not to be superseded by the

4 Bates v. Dow Agrosciences LLC, 544 U.S. 431, 451 (2005).

5 Bates, 544 U.S. at 438 (citing 7 U.S.C. § 136j(a)(1)(E)).

6 Id. at 439 (citing 40 C.F.R. § 159.184(a), (b) (2004)).

7 Id. at 451.

7

Federal Act unless that was the clear and manifest

purpose of Congress.”8 Application of traditional state

law to the tortious misconduct outlined below,

traditionally policed by the State, does not conflict

with and is not different from FIFRA’s statutory goal

of including “a warning or caution statement which

may be necessary and if complied with . . . is adequate

to protect health and the environment.”9

Roundup’s history illustrates why a continuing duty

to update the label exists under FIFRA, and why

private tort suits like Mr. Durnell’s are fully

consistent with the limited preemptive scheme for

pesticide regulation Congress enacted.

STATEMENT

A. Statutory and Regulatory Background

An estimated 325,000 synthetical chemicals and

chemical mixtures exist in the world today. Most of

these chemicals were invented post-1950.

The United States regulates these chemicals under

three different legal regimes, depending on the type of

chemical. First, pharmaceutical agents are

regulated under the Federal Food, Drug, and

Cosmetic Act.10 The manufacturers of these agents

must test them for safety and effectiveness before they

are approved for sale, which includes clinical trials

and post-marketing surveillance. The regulatory

8 Wyeth v. Levine, 555 U.S. 555, 565 (2009).

9 7 U.S.C. § 136(q)(1)(G).

10 21 U.S.C. § 301 et seq.

8

structure is designed to be strict and protective of

public health. But it was not always that way. In the

1950s, a German manufacturer began selling the

sedative drug thalidomide, which soon became a

popular over-the-counter treatment for morning

sickness in pregnant women in Europe. Based on

animal testing, the drug was widely believed to be

non-toxic in humans. After upwards of ten thousand

babies were born with severe deformities to women

who had taken thalidomide during pregnancy, the

drug was banned. This tragedy forced regulators to

address infants’ unique vulnerability to manufactured

chemicals and led to the strict testing requirements

that exist today to ensure another thalidomide

tragedy does not repeat itself.11

Second, industrial and consumer chemicals

products are regulated under the Toxic Substances

Control Act (TSCA).12 TSCA is a weak law without

mandatory

pre-market

screening

and

no

11 Threats to fetal development such as thalidomide are not

unique to pharmaceuticals, but can also result from pesticide

exposure. See The Consortium for Children’s Environmental

Health, Manufactured Chemicals and Children’s Health – The

Need for New Law., N ENGL J MED 392:3, (Jan. 16, 2025)

https://www.nejm.org/doi/full/10.1056/NEJMms2409092.

The

pesticide chlorpyriphos causes long-term alterations in brain

development and behavior of children and offers a prime example

of

the

need

to

police

pesticides.

See

https://www.epa.gov/newsreleases/epa-takes-action-addressrisk-chlorpyrifos-and-protect-childrens-health;

Bradley

S.

Peterson et al., Brain Abnormalities in Children Exposed

Prenatally to the Pesticide Chlorpyrifos, 82 JAMA NEURO. 1057–

1068 (2025), http://doi.org/10.1001/jamaneurol.2025.2818.

12 15 U.S.C. § 2601 et seq.

9

postmarketing surveillance. Fewer than 20% of these

chemicals have been tested for toxicity.

Third, pesticides, including herbicides such as

Roundup, are regulated by the Federal Insecticide,

Fungicide, Rodenticide Act (FIFRA) and the Food

Quality Protection of Act of 1996 (FQPA),13 which

amended FIFRA. FIFRA requires EPA registration of

all domestically sold pesticides. As part of the

registration process, the registrant must perform

long-term animal studies in two species on the active

ingredient of the pesticide.14 The registrant selects the

laboratory to perform the tests (usually in rodents)

and provides the results of the studies to EPA. These

carcinogenicity studies are only performed on the

active ingredient; EPA does not require a pesticide

manufacturer to perform a carcinogenicity study on

the formulated product. Because it would be unethical

to test a pesticide – designed to kill weeds, insects,

rodents, etc. – on a human subject, there are no

human studies available when a product is first

registered, and a pesticide’s carcinogenicity is

evaluated based on animal data alone. That makes the

integrity of animal testing essential for protecting

users of the product and the public at large. In the case

of Roundup, the animal testing performed on

glyphosate for initial registration in 1974 was

fraudulent, leading EPA to invalidate those studies in

1978. See Argument II.B., infra.

13 Pub. L. No. 104-170, 110 Stat. 1489.

14 7 U.S.C. § 136(a)e(1).

10

The FQPA amended FIFRA in 1996 to, among other

things, require registration review every 15 years.15

That makes sense because, as people use or are

otherwise exposed to the pesticide, human

epidemiology

and mechanistic data

become

increasingly available. It is critically important to

evaluate the pesticides’ potential dangers to human

health as science develops. In addition, the FQPA

employs a new standard for establishing pesticide

tolerances, providing that EPA “may establish or

leave in effect a tolerance for a pesticide . . . residue in

or on a food only if the Administrator determines that

the tolerance is safe.”16 “Safe” means “that there is a

reasonable certainty that no harm will result from

aggregate exposure to the pesticide. . . .”17 The statute

omits a cost-benefit analysis for setting tolerances.

Finally, of utmost importance to the question

presented, FIFRA also requires manufacturers to

provide to EPA any adverse information about a

pesticide’s potential risks to human health.18 The

manufacturer cannot wait for registration review if it

receives information that shows previously unknown

dangers.

15 7 U.S.C. § 136a(g); 40 C.F.R. § 155.50(b).

16 21 U.S.C. 346a(b)(2)(B)(ii)–(iv); Thomas McGarity, Politics

by other means: law, science, and policy in EPA’s implementation

of the food quality protection act., ADMIN. LAW REV. 53: 1, 103–

222 (2001), https://www.jstor.org/stable/40711949.

17 Id.

18 7 U.S.C. § 136d(a)(2); 40 C.F.R. pt. 159.

11

B. Scientific and Factual Background

Glyphosate, a broad-spectrum herbicide (weed

killer), was discovered by Monsanto in 1970 as having

herbicidal qualities and patented in the United States

by Monsanto as an herbicide from its registration in

1974 through 2000.19 Glyphosate is the active

ingredient in Monsanto’s Roundup product lines. The

diversity and magnitude of glyphosate/Roundup uses

in agriculture, forestry, industrial and commercial

settings, as well as residentially, have grown

dramatically since first approval in 1974.

Humans are exposed to glyphosate by three

pathways: dermal exposure, inhalation, and

ingestion. Dermal and inhalation exposure occurs

through direct spraying, occupational or residential

proximity to sprayed areas, and dust. Oral exposure

occurs through consumption of glyphosate residues in

food and water. Food is the main route of exposure for

most people in the United States. Recent nationwide

biomonitoring surveys have detected glyphosate in

samples collected from 70–80% of all people examined

in the United States, including children.20

Once glyphosate enters the body, it is rapidly

transported from the bloodstream to bone marrow,

regardless of exposure route. At peak glyphosate

See U. S. Patent 3,799,758 (Mar. 26, 1974)

https://patentimages.storage.googleapis.com/58/51/2c/48674f43b

aa042/US3799758.pdf.

19

20 See, e.g., Maria Ospina et al., Temporal Trends of Exposure

to the Herbicide Glyphosate in the United States (2013-2018):

Data from the National Health and Nutrition Examination

Survey,

364

CHEMOSPHERE

142966

(2024),

http://doi.org/10.1016/j.chemosphere.2024.142966.

12

levels in bone marrow – two to six hours after

exposure – there are likely billions of glyphosate

molecules for every hematopoietic (blood cellgenerating) stem cell. There, glyphosate is known to

trigger some of the precise mutations that initiate

lymphocytes (a type of white blood cell) on the path to

NHL and other blood cancers.

Monsanto has known these facts for most of the time

it has sold Roundup to unsuspecting customers. The

information is largely contained in its own metabolism

studies conducted in the 1980s–1990s, but for years,

rather than sharing the information with EPA as

FIFRA requires (or with consumers to ensure they use

Roundup safely), Monsanto either dismissed or

downplayed these findings as irrelevant. The

Roundup litigation unearthed these studies.

ARGUMENT

I.

Overwhelming Evidence Establishes that

Glyphosate and Glyphosate-Based

Herbicides Cause Cancer.

Glyphosate-based herbicides (GBHs) have been

strongly linked to cancer in humans, not only by the

International Agency for Research on Cancer (IARC),

but also by independent researchers across the globe.

Following the 2015 IARC assessment, scientists,

including amicus Dr. Landrigan, met to evaluate the

existing scientific evidence of glyphosate’s human

health risks, including non-cancer outcomes. These

researchers, in a peer-reviewed statement of concern

about risks associated with GBH exposure, endorsed

IARC’s glyphosate carcinogenicity classification,

concluding that substantial evidence existed at that

time that GBHs could cause non-cancer diseases,

13

including “possible endocrine system-mediated and

development impacts”; adverse effects on the liver and

kidney; gastrointestinal microbiome alteration;

oxidative stress in rat liver; and diseases that have

devastating outcomes for human health.21 In 2021, the

French Institute of Health and Medical Research

(Inserm) also found a link between glyphosate/GBH

exposure and NHL risk in the epidemiologic studies.22

Just last week, a group of scientists held a

symposium to discuss their views on health risks of

GBH exposure. Following the symposium, they

adopted and released a consensus Statement on

Glyphosate, concluding that the evidence of cancer

and non-cancer health effects has grown stronger over

the last ten years:

Glyphosate

and

glyphosate-based

herbicides (GBHs) harm human health

and

can

cause

cancer.

The

comprehensive evidence supports this

conclusion,

with

the

strongest

epidemiological

evidence

linking

exposure to increased risk of nonHodgkin lymphoma, a cancer of the

lymphatic system.

See Myers, et al., Concerns over use of glyphosate-based

herbicides and risks associated with exposures: a consensus

statement.,

ENVIRON

HEALTH

15:19

(2016).

http://doi.org/10.1186/s12940-016-0117-0.

(2016

Myers

Statement of Concern), at 2–3, 5, 7.

21

See INSERM Collective Expertise Centre, Effects of

pesticides on health: New data (EDP Sciences) (2022),

http://www.ncbi.nlm.nih.gov/books/NBK581472/.

22

14

There is additional evidence from human

and/or animal studies that glyphosate

and GBHs increase the risk of multiple

adverse health effects in addition to

cancer, including diseases of the kidney

and liver, and impacts to the

reproductive, endocrine, neurological,

and other metabolic systems. Children,

infants and fetuses are the most

susceptible.

Further strong evidence finds that

glyphosate and GBHs cause genetic

damage, oxidative stress, and hormonal

disruption — biological changes that can

set

disease

in

motion.

Our

understanding of glyphosate’s ability to

cause these changes has developed from

multiple lines of evidence in animal,

human and in vitro studies.

Additional research is needed to better

understand

the

full

extent

of

glyphosate’s and GBH’s effects on

human health and the underlying

mechanisms involved, such as epigenetic

alterations, microbiome disruption and

endocrine effects.

The evidence that glyphosate and

GBHs harm human health at levels

of current use is now so strong that

no additional delays in regulation of

glyphosate

can

be

justified.

Regulatory agencies in countries around

the world should treat glyphosate and

GBHs as hazardous, as some countries

15

have started to do. Agencies should act

without further delay to limit their use,

or eliminate them if legally required, to

protect

public

health. Preventive

measures to reduce human exposures

while handling and applying glyphosate

are accessible, proven effective, and

inexpensive. These actions should be

implemented without delay while

research continues.23

Since IARC’s 2015 review, and the 2016 Myers

Statement of Concern, additional peer-reviewed

epidemiologic, animal, and mechanistic studies have

continued to provide compelling evidence that

glyphosate and GBHs are a cause of NHL, as the

Durnell jury found.24 Additional epidemiologic

Seattle Statement on Glyphosate and Public Health,

available at https://deohs.washington.edu/sgs/statement (last

visited Mar. 30, 2026) (emphasis added).

23

24 See generally Dennis Weisenburger, An Update of Evidence

that the Herbicide Glyphosate (Roundup) is a Cause of NonHodgkin Lymphoma, CLINICAL LYMPHOMA MYELOMA &

LEUKEMIA

S2152265025042855

(2025),

http://doi.org/10.1016/j.clml.2025.11.005 (reviewing relevant

literature published between 2020 and 2025); Dennis

Weisenburger, A Review and Update with Perspective of Evidence

that the Herbicide Glyphosate (Roundup) is a Cause of NonHodgkin Lymphoma, 21 CLINICAL LYMPHOMA MYELOMA AND

LEUKEMIA

621–630

(2021),

http://doi.org/10.1016/j.clml.2021.04.009 (reviewing relevant

literature published 2015–2020); Iemaan Rana, et al., Mapping

the key characteristics of carcinogens for glyphosate and its

formulations: A systematic review, 339 CHEMOSPHERE 139572

(2023),

http://doi.org/10.1016/j.chemosphere.2023.139572

(presenting updated evaluation of mechanistic evidence,

16

evidence

of

statistically

significant

positive

associations between exposure to GBHs and NHL

and/or its various subtypes has emerged.25 Notably,

despite the insistence of Monsanto’s in-house

scientists and paid consultants that it would be

impossible to perform an animal study on formulated

Roundup, an independent Italian research institute

completed and published such a study just last year,

finding statistically-significant and dose-related

increased trends or incidences of tumors at multiple

anatomic sites in rats, at exposure levels even within

permissible European dietary limits.26 And a

substantial body of additional literature provides

including significant new studies published subsequent to the

evidence assessed in 2015 by IARC Working Group).

25 See Paolo Boffetta, et al., Exposure to glyphosate and risk of

non-Hodgkin lymphoma: an updated meta-analysis, 112 LA

MEDICINA

DEL

LAVORO

194–199

(2021),

http://doi.org/10.23749/mdl.v112i3.11123 (presenting updated

meta-analysis finding significantly increased risk for diffuse

large B-cell NHL with higher exposure to glyphosate); Federico

Meloni et al., Occupational exposure to glyphosate and risk of

lymphoma: results of an Italian multicenter case-control study, 20

ENVT’L HEALTH 49 (2021), http://doi.org/10.1186/s12940-02100729-8 (finding four-fold increase in risk of B-cell NHL among

workers with medium to high intensity exposure); Lennart

Hardell et al., Exposure to phenoxyacetic acids and glyphosate as

risk factors for non-Hodgkin lymphoma- pooled analysis of three

Swedish case-control studies including the sub-type hairy cell

leukemia, 64 LEUKEMIA & LYMPHOMA 997–1004 (2023),

http://doi.org/10.1080/10428194.2023.2190434

(finding

statistically significant increased risk of NHL in pooled analysis

of three case-control studies).

26 Simona Panzacchi, et al., Carcinogenic effects of long-term

exposure from prenatal life to glyphosate and glyphosate-based

herbicides in Sprague–Dawley rats, 24 ENVIRON. HEALTH 36

(2025), http://doi.org/10.1186/s12940-025-01187-2 .

17

further evidence that glyphosate and GBHs are

genotoxic to human lymphocytes and other cells, now

including direct evidence of genetic damage in

occupational glyphosate users.27 Beyond NHL,

emerging evidence of glyphosate’s carcinogenicity also

points to other cancer endpoints including acute

myeloid leukemia,28 multiple myeloma,29 and breast

cancer.30

27 Vicky Chang, et al., The association between glyphosate use

and mosaic loss of chromosome Y in buccal samples among male

pesticide applicators in the Agricultural Health Study, 203

ENVIRONMENT

INTERNATIONAL

109755

(2025),

http://doi.org/10.1016/j.envint.2025.109755 (reporting positive

associations between exposure to GBHs and a chromosomal

alteration indicative of genotoxicity, genomic instability, and

immune dysregulation, based on buccal samples, supplementing

similar findings by researchers in earlier study using blood

samples).

28 See, e.g., Panzacchi (2025), supra.

See, e.g., Lei Wang, et al., Glyphosate induces benign

monoclonal gammopathy and promotes multiple myeloma

progression in mice, 12 J. HEMATOLOGY & ONCOLOGY 70 (2019),

http://doi.org/10.1186/s13045-019-0767-9.

29

30 See, e.g., Hannah Schluter, et al., Potential Role of

Glyphosate, Glyphosate-Based Herbicides, and AMPA in Breast

Cancer Development: A Review of Human and Human Cell-Based

Studies, 21 INT’L J. ENVIRON RESEARCH PUB. HEALTH 1087

(2024),

http://doi.org/10.3390/ijerph21081087

(reviewing

available literature on relationship between exposure to GBHs

and breast cancer, including series of studies showing higher

urinary levels of glyphosate and/or its metabolite AMPA were

associated with breast cancer risk, higher levels of oxidative

stress biomarkers, endocrine disruption, and DNA methylation

differences); Lyvia Neves Rebello Alves et al., Glyphosate-Based

Herbicide as a Potential Risk Factor for Breast Cancer, 200 FOOD

CHEM.

TOXICOL.

115404

(2025),

http://doi.org/10.1016/j.fct.2025.115404 (reporting results of in

18

A growing body of research also links glyphosate

and/or GBHs to other significant non-cancer health

effects. For example, multiple studies employing

different methodologies and examining distinct

populations have shown an association, and a doseresponse relationship, between glyphosate exposure

and liver injury, fatty liver disease, metabolic

syndrome, and glucose dysregulation including

development of Type II diabetes.31 Multiple studies

have also found an association between glyphosate

exposure and adverse neurodevelopmental outcomes,

with similar findings arising whether exposure is

assessed by proximity to the use of glyphosate-based

herbicides or by direct measurement of glyphosate

and its metabolite, AMPA, in urine.32 Glyphosate –

which Monsanto patented as an antibiotic – has also

been shown to disrupt the human gut microbiome,

with serious implications for human immune

function, among other things.33 And a growing body of

vitro tests showing exposure to GBHs alters expression of key

breast cancer-related genes).

31 See, e.g., Kexing Han, et al., Analysis of the association

between urinary glyphosate exposure and fatty liver index: a study

for US adults., BMC PUB. HEALTH 24:703 (2024)

http://doi.org/10.1186/s12889-024-18189-3; Wenxiang Li, et al.,

Association of glyphosate exposure with multiple adverse

outcomes and potential mediators., CHEMOSPHERE 345:140477

(2023). http://doi.org/10.1016/j.chemosphere.2023.140477.

32 See, e.g., Ondine von Ehrenstein, et al., Prenatal and infant

exposure to ambient pesticides and autism spectrum disorder in

children: population based case-control study, 364 BMJ l962

(2019), http://doi.org/10.1136/bmj.l962.

33 See, e.g., Robin Mesnage et al., Alterations in infant gut

microbiome composition and metabolism after exposure to

glyphosate and Roundup and/or a spore-based formulation using

19

evidence points to GBHs as an endocrine disruptor34

and potential reproductive toxicant,35 at levels

associated with dietary and bystander exposure.

II.

Granting Immunity from Label-Based Tort

Liability Would Incentivize the Type of

Deceit Monsanto Exhibited in Relation to

Roundup.

Based on Monsanto’s 50-year history of hiding

important adverse health information from the public

and denigrating scientists who dare to publish

adverse information about Roundup’s safety,36 amici

are concerned that a decision that Mr. Durnell’s

claims are preempted would incentivize future

pesticide registrants to deceive EPA in the

registration process. As to existing registrants, a

finding of preemption would incentivize them to hide

the SHIME technology, 3 GUT MICROBIOME (Cambridge,

England) e6 (2022), http://doi.org/ 10.1017/gmb.2022.5.

See, e.g., Siriporn Thongprakaisang et al., Glyphosate

induces human breast cancer cells growth via estrogen receptors,

59

FOOD

&

CHEM.

TOX.

129–136

(2013), http://doi.org/10.1016/j.fct.2013.05.057.

34

35 See, e.g., David Haas et al., First trimester urine glyphosate

concentrations and gestational diabetes in nulliparas: a nested

case-control

study,

24

ENVT’L HEALTH

71

(2025),

http://doi.org/10.1186/s12940-025-01183-6.

See, e.g., Gilles-Eric Séralini et al., Conflicts of interests,

confidentiality and censorship in health risk assessment: the

example of an herbicide and a GMO, 26 ENVT’L SCI. EUROPE 13

(2014), http://doi.org/10.1186/s12302-014-0013-6; Int’l Agency for

Research on Cancer, IARC Response to criticisms of the

Monographs and the glyphosate evaluation (Jan. 2018),

https://www.iarc.who.int/wpcontent/uploads/2018/07/IARC_response_to_criticisms_of_the_

Monographs_and_the_glyphosate_evaluation.pdf.

36

20

adverse public health information they receive after

registration. These perverse outcomes are inimical to

Congress’ intent when it established our pesticide

regulation scheme. The Roundup litigation confirms

that EPA’s registration review is incomplete, nondefinitive, and not an appropriate basis for

preemption given its factual and scientific

deficiencies. But for the Roundup litigation and the

information plaintiffs uncovered about Monsanto’s

decades-long suppression of adverse scientific

evidence about Roundup’s carcinogenicity (and other

negative health outcomes) from EPA and the public,

the important health-based evidence Monsanto

possessed but “archived” before it had to produce it in

discovery would never have seen the light of day.

Monsanto’s manipulation of the science – illustrated

by key events in the history of Roundup regulation

– cannot be overstated.

A. The IBT Scandal

In 1971, Monsanto contracted with a commercial

laboratory, Industrial Bio-Test (IBT), to perform most

of the testing necessary to support EPA’s Roundup

registration, including two long-term cancer tests in

rodents (rats and mice). At the time, no other

manufacturers had reason to test glyphosate, which

Monsanto patented, and human studies would have

been impossible and unethical. IBT’s rodent studies

would remain the only available carcinogenicity

studies on glyphosate for the first nine years of

Roundup’s registration for sale in the United States.

21

But those tests were fraudulent.37 At IBT, a former

Monsanto toxicologist named Paul Wright – whom

IBT hired at the request of a Monsanto executive –

planned and oversaw the rodent and dog studies on

glyphosate. According to a lab technician who worked

in the rat study room, IBT had so many ongoing

studies that technicians could not keep up with the

necessary tasks – weighing the animals, measuring

and logging their feed, and removing dead animals for

pathologic examination. To cure the gaps this left in

their lab notebooks, Wright and another IBT

toxicologist, James Plank, falsified the missing data.38

Meanwhile, when test animals died, some were

replaced with healthy substitutes, while others were

not discovered until they were too decomposed for the

necessary pathology examinations.39 Wright saw

these conditions daily. Fourteen months after IBT

undertook the glyphosate studies, Wright returned to

work at Monsanto, where he supervised the

completion of IBT’s glyphosate studies and approved

the final study reports submitted to EPA.40

37 See, e.g., Tr. 1020–1023; David Rosner & Gerald Markowitz,

“Ashamed to Put My Name to It”: Monsanto, Industrial Bio-Test

Laboratories, and the Use of Fraudulent Science, 1969-1985, 113

AM.

J.

PUB.

HEALTH

661–666

(2023)

https://pmc.ncbi.nlm.nih.gov/articles/PMC10186829/;

Keith

Schneider, et al., Faking It: The Case Against Industrial Bio-Test

Laboratories,

Amicus

Journal

(Spring

1983)

https://www.centerforfoodsafety.org/files/schneider1983_42309.pdf.

38 See United States v. Keplinger, 776 F.2d 678, 685 (1985), cert.

denied., 476 U.S. 1183 (1986); Pilliod v. Monsanto Co., 282

Cal.Rptr.3d 679, 710 (Cal. App. 1 Dist., 2021).

39 See, e.g., Keplinger, 776 F.2d at 697.

40 Pilliod, 282 Cal.Rptr.3d at 710.

22

IBT issued its final report on the 18-month mouse

study in September 1973, and its report on the 2-year

rat study followed a few months later, both written by

Manuel S. Reyna and approved by Moreno Keplinger,

IBT’s Manager of Toxicology. Neither study reported

any indication of cancer risk, though EPA found

treatment-related liver changes in the rat study

forecasting what researchers have found in more

recent human studies.41 EPA granted the registration

of glyphosate within a few months of receiving the IBT

reports.

In 1976, the Food and Drug Administration (FDA)

conducted a routine inspection of IBT’s laboratories,

revealing gross deficiencies that cast doubt on the

integrity of all IBT’s rodent studies. Because IBT’s

safety tests had supported the regulatory approvals

for hundreds of products sold in the United States,

EPA and FDA announced plans to audit all IBT

toxicity tests supporting pesticide registrations.42 To

say that this provoked a regulatory crisis would be an

understatement – the IBT scandal triggered a

Congressional investigation and ultimately a

wholesale revision of regulatory requirements,

41 See, e.g., Luana Riechelmann-Casarin et al., Are Glyphosate

or Glyphosate-Based Herbicides Linked to Metabolic DysfunctionAssociated Steatotic Liver Disease (MASLD)? The Weight of

Current Evidence, 116 ENVIRON. TOXICOL. PHARMACOL. 104705

(2025), http://doi.org/10.1016/j.etap.2025.104705.

42 See generally Office of Pesticide Programs, Summary of the

IBT

Review

Program

(July

1983).

https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=91014ULV.txt.

(EPA Summary).

23

including the implementation of the Good Laboratory

Practice standards still used today.43

News of the federal government’s investigation

naturally alarmed IBT and one of its biggest

customers, Monsanto. In July 1977, IBT’s president

and legal counsel met with Monsanto executives,

telling them point blank that IBT’s animal studies –

specifically the glyphosate mouse and rat

carcinogenicity studies – contained “extrapolation”

and “faulty interpretations” that likely constituted

“fraud.”44 Though Wright had directly overseen those

likely fraudulent studies from start to finish,

Monsanto promptly put him in charge of its newly

established in-house animal testing lab. Monsanto

also hired two other scientists who had worked on

studies of various Monsanto products at IBT: Reyna

(co-author of the IBT glyphosate rodent studies) and a

veterinary pathologist, William Ribelin, whom it put

to work re-examining the tissue samples from the IBT

rat study. Meanwhile, Monsanto continued selling

Roundup products without warning farmers or

residential users that the product’s safety was in

question (as it had no valid carcinogenicity studies)

and without telling the EPA (before EPA found out on

its own the following year) about the fraud in the IBT

studies that supported EPA’s registration of Roundup.

43 See generally Anne Baldeshwiler, History of FDA good

laboratory practices, 7 QUALITY ASSURANCE J. 157–161 (2003),

http://doi.org/10.1002/qaj.228.

See Mem. re: IBT Audit and Revalidation of Toxicology

Studies Letter (July 13, 1977), PCB-ARCH0705738–41,

https://www.toxicdocs.org/d/r3EnYLgeRGvQVrRwOQN7ev2q?li

ghtbox=1.

44

24

By August 1978, the federal government had

audited most of IBT’s glyphosate studies. EPA

declared IBT’s 18-month glyphosate mouse study

invalid after finding too many test animals missing.45

In the 2-year rat study, EPA found insufficient

reporting on the histopathology findings in the control

and treatment groups and approximately 70 animals

unaccounted for across the study.46 EPA further

invalidated three of IBT’s four glyphosate genotoxicity

(mutagenicity) studies because of missing vital

validation data.47 EPA concluded that “adequate

oncologic studies should be initiated as soon as

possible.”48 In response, five years later, Monsanto

submitted a mouse carcinogenicity study that, to

Monsanto’s surprise, led EPA to initially categorize

glyphosate as “Category C oncogen,” i.e., a possible

human carcinogen. Meanwhile, Monsanto publicly

maintained that based on these long-term animal

studies, glyphosate had been shown not to cause

cancer.49

By 1983, the government’s investigation found that

nearly three-quarters of the 801 IBT health effects

studies submitted for regulatory approvals were

45 See EPA Summary at 37.

46 P-0309-128 (citations in this format refer to exhibits

admitted in the trial below and included in the appellate record).

47 See Revised Glyphosate Issue Paper at 70.

48 EPA Mem. re: Glyphosate tolerances (Aug. 22, 1978),

https://archive.epa.gov/pesticides/chemicalsearch/chemical/foia/

web/pdf/103601/103601-065.pdf.

49 Monsanto, Roundup® Herbicide Bulletin No. 1 (Dec. 1980),

MONGLY04267426.

25

invalid.50 A grand jury indicted Wright, Keplinger,

and Plank for fraud in connection with four different

IBT studies, including a study on Monsanto’s product

TCC.51 In the six-month criminal trial that followed,

Monsanto’s employees featured prominently: Wright,

as a defendant, and Reyna and Ribelin as scientists

who had worked on the TCC studies. In October 1983,

the jury convicted all three defendants of various

federal crimes. The Seventh Circuit Court of Appeals

affirmed their convictions, and this Court denied a

writ of certiorari.

Rather than firing Wright and distancing itself from

his fraud, Monsanto employed him for months after

his criminal conviction and paid over a million dollars

for his legal defense. Monsanto also continued to

employ Reyna, who, in 1990, authored a rodent study

that Monsanto used to persuade EPA to dramatically

increase the permissible level of glyphosate consumed

by Americans – despite an earlier study by an outside

laboratory showing kidney lesions at those dose

levels.52

50 EPA Summary at 3.

51 Keplinger, 776 F.2d at 684.

See, e.g., EPA, Drinking Water Criteria Document for

Glyphosate

Final

(Jan.

1992),

at

40.

https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=901H0700.txt

(citing M.S. Reyna, Final Report, Two Generation Reproduction

Feeding Study with Glyphosate in Sprague-Dawley Rats, Project

No. ML-88-106/EHL 88038 (Aug. 27, 1990)).

52

26

B. Continued Manipulation of

Carcinogenicity Data: The Magic Tumor

Based on the study data from the repeat mouse

study, which showed a statistically significant, doserelated tumor increase, EPA determined in March

1985 that glyphosate should be classified as a possible

human carcinogen.53 Monsanto met with EPA, hoping

to prevent EPA’s proposed classification from

becoming official.54 Monsanto understood there was

only one way to avoid an oncogen classification: to

convince EPA to allow it to re-review the slides and to

“find” a tumor in the control group.55 And that is what

occurred: EPA allowed Monsanto to re-review the

slides, and Monsanto hired a friendly animal

pathologist named Dr. Kuschner to do so. Another

internal Monsanto memorandum shows Kuschner

and Monsanto decided, before Kuschner even received

the slides, that Kuschner would find a kidney tumor

in the control group.56 And lo and behold, Monsanto

sent Kuschner’s report to the EPA, reporting that

Kuschner “discovered a tumor in a control mouse” but

otherwise confirmed the original study findings.57

EPA scientists disputed Kuschner’s finding, but

nevertheless informed Monsanto that “the Agency is

requiring that this study be repeated with a larger

number of animals in each test group, so that the

53 EPA, Glyphosate; Pesticide Tolerances, 62 Fed. Reg. 17723,

17724 (April 11, 1987).

54 P-0316-001.

55 P-0316-003.

56 P-0318-001.

57 P-1655-001.

27

statistical power of the study is increased.”58 To this

day – 40 years and billions of dollars in sales later –

Monsanto has not conducted the repeat mouse study.

C. Suppression of Expert Information

Relating to Roundup’s Genotoxicity

In the mid-1990s, Monsanto learned about recently

published, peer reviewed articles that showed

Roundup to be genotoxic. These studies coincided with

Monsanto’s upcoming re-registration of glyphosate in

Europe.

Monsanto

hired

a

world-renowned

toxicologist, Dr. James Parry, to assess the published

genotoxicity studies and make recommendations for

countering their conclusions. Monsanto’s chief

toxicologist, Williams Heydens, proposed that Parry

should only review four of the studies and, depending

on his viewpoint, the company would decide whether

to expand his work or terminate him.59 In an initial

report dated February 11, 1999, Parry wrote that

based on his review of the first four papers, “[t]he

overall data . . . provide evidence to support a model

that Glyphosate is capable of producing genotoxicity

both in vivo and in vitro by a mechanism based upon

the production of oxidative damage.”60 Monsanto

executives privately debated whether it was possible

to “turn his opinion around.”61 They decided to let

58 P-1532-018.

59 See Memo and Emails re: DRAFT of Minutes (Jan. 28, 1999),

https://usrtk.org/wp-content/uploads/bsk-pdfmanager/2019/01/Monsanto-1999-email-thread-re-Parry-andtesting.pdf.

60 P-0758-011.

61 Email from Martens (Apr. 19, 1999), MONGLY06486905.

https://usrtk.org/wp-content/uploads/bsk-pdf-

28

Parry review all the mechanistic data and report his

findings, hoping that the larger body of literature

would change his mind. But they first required Parry

to sign a “secrecy agreement.”62 He did so, and

continued his review, suggesting additional research

and concluding that:

If the genotoxic activity of glyphosate

and its formulations is confirmed it

would be advisable to determine whether

there are exposed individuals and groups

within the human population. If such

individuals can be identified, then the

extent of exposure should be determined

and their lymphocytes analyzed for the

presence of chromosome aberrations.63

In response, Monsanto executives privately

complained they had fallen into a “genotox hole” and

wondered whether they could find an “independent”

scientist to dig them out.64 Monsanto’s chief

toxicologist Heydens, acknowledged that the company

“was vulnerable in [the] area” of genotoxicity, but

determined that Monsanto would not conduct any of

the follow-up studies Parry recommended.65

manager/2019/01/Exhibit-1999-meeting-minutes-re-Parry-andgenotox-issues.pdf.

62 Id.

63 P-0153-035.

64 P-0154-001.

65 P-0156-001.

29

The Parry reports are the type of information that

FIFRA section 6(a)(2) required Monsanto to provide to

EPA: “new adverse data on a pesticide in the

possession of registrants must be reported to the

EPA within 90 days, including data in preliminary

reports.” But Monsanto never provided Parry’s report

to the EPA. It was only revealed to the public eighteen

years later, through the Roundup litigation.

With Parry fired and no cover for the genotoxicity

threat, Monsanto decided to ghostwrite an article and

pay Dr. Gary Williams, “recognized internationally as

a genotox expert,” to “author” the paper.66 Williams

published the paper, entitled “Safety Evaluation and

Risk Assessment of the Herbicide Roundup and its

Active Ingredient, Glyphosate, for Humans” in the

journal Regulatory Toxicology and Pharmacology in

2000, without crediting the Monsanto scientists who

had actually written it.67 A post-publication internal

memorandum touts the work of Monsanto’s in-house

scientists in publishing the article, bragging that it

would be used “in both the defense of Roundup and

Roundup Ready crops worldwide.”68 EPA and many

other regulatory agencies around the world, as well as

academics and other researchers, relied on the

Williams paper, not knowing it was written by

66 P-0757-002.

67 Gary Williams et al., Safety Evaluation and Risk Assessment

of the Herbicide Roundup and Its Active Ingredient, Glyphosate,

for Humans, 31 REG. TOX. & PHARM. 117–165 (2000),

http://doi.org/10.1006/rtph.1999.1371.

68 Email from Grant (May 12, 2000), MONGLY02624347–49.

https://usrtk.org/wp-content/uploads/bsk-pdfmanager/2019/04/Ghostwriting-Monsantos-CEO-praisesemployees-for-publication-of-Williams-Kroes-Munro-Study.pdf.

30

Monsanto.69 Twenty-five years later, in October 2025,

the journal retracted the paper, in response to

information about Monsanto’s ghostwriting practices

that only became public through the Roundup

litigation.70

D. The Dermal Penetration Study Coverup

In the early 2000s, Monsanto hired the laboratory

TNO to conduct rat and human dermal penetration

tests for Roundup. Initial results showed dermal

absorption of glyphosate at rates more than three

times what had previously been assumed. When

Monsanto’s chief toxicologist Heydens learned about

the high penetration results, his primary concern was

“the potential for this work to blow Roundup risk

evaluations.71 Monsanto halted the study.72

Monsanto did not share these adverse findings with

EPA, in violation of FIFRA. Studies that a registrant

69 Alexander Kaurov et al., The afterlife of a ghost-written

paper: How corporate authorship shaped two decades of

glyphosate safety discourse, 171 ENVIRONMENTAL SCIENCE &

POLICY

104160

(Sept.

2025).

http://doi.org/10.1016/j.envsci.2025.104160.

Martin van den Berg, Retraction Notice for “Safety

Evaluation and Risk Assessment of the Herbicide Roundup and

Its Active Ingredient, Glyphosate, for Humans,” REG. TOX &

PHARM. (2025), http://doi.org/10.1016/j.yrtph.2025.106006.

70

71 Email from Heydens (Apr. 2, 2002), MONGLY03738295–6,

https://usrtk.org/wp-content/uploads/bsk-pdfmanager/2019/01/Monsanto-discussion-of-dermal-absorptionissues.pdf.

Email from Garnett (Apr. 5, 2002), MONGLY03737015,

https://corporateeurope.org/sites/default/files/attachments/47monsanto-personnel-further-study-on-glyphosateabsorption.pdf.

72

31

terminates before completion must be reported to

EPA, with the reasons for termination.73

III.

IARC’s 2015 Findings Linking Glyphosate

with Cancer Have Ample Scientific

Support, Notwithstanding Petitioner and

Its Amici’s Criticisms.

Rather than address the strong scientific evidence

linking glyphosate with cancer, Petitioner and its

supporting amici characterize this as an invention of

IARC, which they wrongly caricature as a flawed and

conflicted body biased towards finding hazards where

none exist.74 This mockery of IARC has no legs. IARC’s

detailed and well-supported finding that glyphosate is

carcinogenic disclosed to the public critically

important health information, despite Petitioner’s

and its industry trade groups’ successful suppression

of science for decades.

IARC’s scientific cancer reviews and monographs

are well known and highly respected in the scientific

community and routinely relied upon by courts.75 It is

exactly that prestige that caused Monsanto (for years)

to dread IARC’s review of glyphosate. To neutralize

IARC’s glyphosate assessment, Monsanto planned an

“orchestrated outcry” in advance, and convened a

panel of paid-for “independent experts” to discredit

IARC’s assessment before it was even completed or

73 40 C.F.R. § 159.167.

74 E.g., Brief of Amici Curiae Americal Tort Reform

Association, at 6–18.

75 “[W]hen IARC monographs are available, courts generally

recognize them as authoritative.” Fed. Judicial Ctr., REF. MAN.

ON SCIENTIFIC EVID. (4th ed. 2025) at 920.

32

published.76

In March 2015, an IARC working group of 17

independent experts from 11 countries, having spent

months reviewing the published scientific evidence,

met to evaluate the carcinogenicity of five

organophosphate

insecticides

and

herbicides

including glyphosate.77 Based on the Working Group’s

analysis of animal data, mechanistic data, and

epidemiology, IARC classified glyphosate as “probably

carcinogenic to humans” (Group 2A). The pesticide

Monograph, like other IARC monographs, was “based

on the systematic assembly and review of all publicly

available and pertinent [peer-reviewed] studies, by

independent experts, free from vested interests.”78

Petitioner

and

amici

mischaracterize

the

significance of hazard assessments like those

performed by IARC. IARC’s hazard assessments

address an agent’s carcinogenic potential to cause

cancer (and as to Roundup, whether Roundup

exposure can cause NHL). Regulatory bodies like EPA

undertake the same hazard analysis but never reach

the next regulatory step of performing a “risk

assessment” unless they first determine that a

substance is a “hazard.” Contrary to amici Americal

Tort Reform Association, the EPA did not conduct a

76 See, e.g., P-0746-007, P-0393-003; Email from Link (Feb. 12,

2015),

MONGLY01021708–711,

http://www.wisnerbaum.com/wp-content/uploads/ptx-0379-monemail-revised-iarc-reactive-meeting.pdf.

77 IARC Monograph on Glyphosate, IARC: WHO (July 19,

2018),

https://www.iarc.who.int/featured-news/media-centreiarc-news-glyphosate/.

78 Id.

33

risk assessment for glyphosate “that incorporate[s]

hazard

identification,

dose-response

analysis,

exposure assessment, and risk characterization.”79

EPA, like IARC, performed a glyphosate hazard

assessment; but in the course of doing so, violated its

own carcinogenicity guidelines.80

Petitioner and amici’s criticism that IARC considers

only published papers similarly lacks merit. IARC’s

practice avoids to the extent possible unpublished,

unreviewed, and possibly biased findings pushed by

registrants seeking regulatory approval. This ensures

that IARC’s assessment rests on transparent and

reproducible findings that have withstood the scrutiny

of peer review.81

Last, amici criticize IARC for changing its

classification system to remove Group 4 (“probably not

carcinogenic”), leaving Group 3 (“not classifiable as to

79 Brief of Amici Curiae Americal Tort Reform Association at

5.

80 Nat. Res. Def. Council v. EPA, 38 F. 4th 34, 47, 49 (9th Cir.

2022) (vacating EPA analysis in part because “EPA’s Cancer

Paper uses historical-control data selectively and in a manner

that is inconsistent with the Cancer Guidelines,” and “EPA’s

disregard of tumor results occurring at high dosages conflicts

with the guidelines EPA purports to follow”).

81 Petitioner and its amici spuriously suggest IARC is a fringe

organization by referring to other assessments, such as those for

red meat and processed meats, and very hot beverages. See, e.g.,

Brief of Amicus Curiae Americal Tort Reform Ass’n at 8. While

amici mock these as far-fetched, they rest in scientific evidence

and reflect well-known associations accepted by groups such as

the American Cancer Society (which warns of the risk associated

with red and processed meat consumption) and the American

Institute for Cancer Research (which also acknowledges these

links).

34

its carcinogenicity”) as the category reflecting the

lowest level of evidence. Amici brief at 9. That change

simply reflects IARC’s role in reviewing agents for

which some data already indicates a potential

carcinogenic hazard.82 It has no bearing on whether

IARC validly assesses some agents as probable or

known carcinogens.

IV.

The Scientific Evidence Linking

Glyphosate with Cancer Goes Far Beyond

IARC’s Analysis and Has Only Become

Stronger Over Time.

Mr. Durnell’s trial evidence that Roundup causes

cancer was not limited to IARC’s analysis, nor are

successful Roundup plaintiffs meeting their

demanding scientific evidentiary burdens by relying

on IARC alone. Before any Roundup trials ever took

place, the Judge overseeing the federal multi-district

litigation found that plaintiffs’ experts’ opinions were

admissible only where they “went beyond the inquiry

conducted by IARC.”83 Accordingly, experts at

Roundup trials have been allowed to testify that

Roundup causes cancer only where they have

“offer[ed] independent and relatively comprehensive

opinions that the epidemiological and other evidence

demonstrates glyphosate causes NHL in some people

who are exposed to it.”84 So where “expert opinions []

simply parrot[ed] IARC's analysis” they were

See

IARC

Monographs

Preamble

https://monographs.iarc.who.int/wpcontent/uploads/2019/07/Preamble-2019.pdf.

82

(2019).

83 In re Roundup Prods. Liab. Litig., 390 F. Supp. 3d 1102,

1109 (N.D. Cal. 2018).

84 Id.

35

excluded as “insufficient to satisfy the plaintiffs'

burden.”85

Indeed, since the 2015 IARC-issued glyphosate

monograph, the body of evidence supporting

Roundup’s link to cancer has exploded. And

importantly this explosion of science includes direct

human evidence. As one scientific publication noted:

“The number of journal articles published yearly on

glyphosate and GBHs has increased steadily since the

commercialization of glyphosate in 1974, with nearly

a 4-fold increase in the last 10 years alone” as

illustrated by the following chart:86

85 Id. at 1115.

86 Rachel Lacroix & Deborah Kurrasch, Glyphosate Toxicity: In

Vivo, In Vitro, and Epidemiological Evidence, 192 TOX. SCIS. 131

(2023), http://doi.org/10.1093/toxsci/kfad018.

36

Thus, most of the science that the parties rely on at

Roundup trials postdates IARC, as well as the EPA

assessments that were unanimously vacated by a

Ninth Circuit panel consisting of Judge Wallace,

Judge Boggs (sitting by designation), and Judge

Friedland.87 Not only is Monsanto’s depiction of

Durnell’s scientific case objectively wrong in light of

this record, the rule Monsanto asks for would be

antithetical to the functioning of FIFRA, which

“contemplates that pesticide labels will evolve over

time, as manufacturers gain more information about

their products’ performance in diverse settings,”88

Congress understood this evolution was necessary,

because direct human health studies can only occur

after pesticides are brought to market and their labels

approved by EPA. And where the endpoint being

studied is one involving a long latency period like

cancer, knowledge can take decades to develop.

Affirming the Missouri Court of Appeals’ decision

would therefore be fully consistent with the pesticide

regulatory scheme set forth by Congress. EPA’s

upfront review of all pesticide registrations is limited;

its review of Roundup in particular was marred by

fraudulent misconduct, and further hobbled by

Monsanto’s deceptive conduct; and years of

subsequent research have confirmed the strong

association between glyphosate and cancer in

humans.

87 See Nat. Res. Def. Council, 38 F. 4th at 34.

88 Bates, 544 U.S. at 451.

37

CONCLUSION

For the reasons above, the Court should affirm the

judgment of the Missouri Court of Appeals.

Respectfully submitted,

ALANI GOLANSKI

Counsel of Record

ROBIN L. GREENWALD

ALICIA BUTLER

ROBERT QUIGLEY

WEITZ & LUXENBERG P.C.

700 Broadway

New York, NY 10003

(212) 558-5500

April 1, 2026

DAVID WOOL

WOOL TRIAL LAW LLC

1001 Bannock Street

Suite 410

Denver, CO 80204

(720) 370-6576