PREAMBLE:
More than 60 countries worldwide have banned the killer
herbicide paraquat, including China: but not the USA.
Nearly
60 years ago, a chemical company found that skin exposure
to very high doses of its weed killer paraquat caused “weakness
and incoordination” in rabbits. Large amounts of the
herbicide, which is used on corn, cotton, and vineyards, caused
some mice and rats in its labs to develop a stiff gait or
tremors. A decade later, an autopsy of a farm worker exposed
to paraquat showed “degenerative change” in the
“cells of the substantia nigra,” a pathological
hallmark of Parkinson's disease.
Rather
than remove this dangerous chemical from the market or develop
a safer alternative, the company doubled down on its “blockbuster”
product and sought to expand its use. Along the way, the company
appeared to use techniques to underestimate the toxic effects
of the chemical, hide the results of its own research from
regulatory authorities, and discredit the research of an academic
investigator and prevent her from serving on a U.S. Environmental
Protection Agency (EPA) advisory panel. These are just some
of the findings (Table 1) that the British newspaper the Guardian
recently uncovered after examining the company's internal
records.
TABLE
1. Select findings from the Guardian report on the
manufacturer's actions on its weed killer paraquat, 1955–19852
Year Event
1955 Company identifies paraquat as a potent weed killer
1962 Company introduces paraquat (brand name Gramoxone) into
the United Kingdom and later the United States.
1964 Company finds skin exposure to paraquat in rabbits in
very high doses causes “weakness and incoordination”
1966 Company scientists find that some rats and mice given
large doses of paraquat display a stiff gait or tremors
1968 Poisoning deaths and suicides due to paraquat start to
increase
1974 State regulators express concerns about workers “who
might inadvertently lick small quantities of paraquat residue
off lips, or inhale paraquat mist”; rumors circulate
that some in the EPA are in favor of banning paraquat
1975 Meeting between chemical companies reports that long-term
spraying could injure the central nervous system
1976 Autopsy of farm worker shows “degenerative changes”
in the “cells of substantia nigra”
1985 Company memo reports scientific article showing “extraordinarily
high correlation of .967 was found between levels of pesticide
use and Parkinson's cases.” Memo warns that paraquat
could become a huge legal liability like asbestos and says,
“Parkinson's can go on for decades”
Abbreviation: EPA = U.S. Environmental Protection Agency.
The company's alleged efforts seem to have worked brilliantly.
Despite numerous animal and epidemiological studies linking
the environmental toxicant to Parkinson's disease, paraquat's
use in the United States from 2013 to 2018 more than doubled.
As pesticides can contaminate drinking water and pollute the
air, their harmful effects are not limited to farmers but
extend (at least) to other rural residents who also have a
higher risk of developing Parkinson's disease. Because of
its health risks, over 30 countries—including China—have
banned paraquat. Yet in 2021 the EPA reauthorized its use
even though its own website says, “One Sip Can Kill.”
AGNOTOLOGY
= THE DELIBERATE PRODUCTION OF IGNORANCE
The actions that the manufacturer of paraquat has been accused
of taking are just the latest example of agnotology. Agnotology,
coined by the linguist Iain Boal in 1992, is the deliberate
production of ignorance often for commercial gain. The doubt
can be created by inaccurate or misleading scientific data,
disinformation, document destruction, and secrecy and suppression.
As opposed to the ignorance that a child may have as a “native
state” that can be filled with education, the ignorance
induced by agnotology is “made, maintained, and manipulated.”
According
to the historian Robert Proctor, the classic example of this
ignorance creation is the tobacco industry's long campaign
(“Doubt is our product”) to mask the health risks
of smoking. The industry simultaneously feigned its own ignorance,
affirmed the absence of definitive proof, and created doubt
within the public at large. The result was millions of avoidable
deaths, enormous economic costs borne by individuals and societies,
and immeasurable personal suffering.
The
makers of paraquat apparently have done the same. Knowledge
of the toxic effects of paraquat is alleged to have been hidden
for decades, and a credible academic researcher appears to
have been prevented from highlighting the weed killer’s
true risks. All the while, the manufacturer continues to maintain
that paraquat does not cause Parkinson's disease. Actions
like these should be recognized for what they are: attacks
on science, attacks on scientists, and attacks on the health
of the public.
ATTACKS
ON SCIENCE AND A SCIENTIEST
The goal of science is to advance knowledge. The purpose of
agnotology is to obscure it.
According
to the Guardian, in 2009 the makers of paraquat were
trying to determine if “the scientific community [will]
conclude from the laboratory and epidemiological data that
paraquat exposure is a causal factor [their emphasis] in Parkinson's
Disease or parkinsonism.” It appears that this is a
conclusion the company did not want us Parkinson's researchers
to make. This report and the company's own findings now indicate
that we know what one cause of Parkinson's disease is—paraquat.
With this conclusion, paraquat should be banned, and the search
for other causative factors in the environment should accelerate.
The
attack on a Parkinson's researcher also should not go unanswered.
Dr. Deborah Cory-Slechta is a highly regarded neurotoxicologist
who with her colleagues in 1999 found that in mice “systemically
absorbed paraquat crosses the blood-brain barrier to cause
destruction of dopamine neurons in the substantia nigra, consequent
reduction of dopaminergic innervation of the striatum and
a neurobehavioral syndrome similar” to that produced
by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. Two decades
later in 2021, she and her fellow researchers demonstrated
that inhaled paraquat concentrates in the olfactory bulb and
enters all regions of the brain that were examined while bypassing
the blood–brain barrier.
To
prevent her service on an EPA advisory panel on pesticides
in 2005, the manufacturer, according to the Guardian,
asked an industry lobbying group to “disparage Cory-Slechta's
work in communications to the EPA.” Because the company
was apparently concerned that such comments could later be
used against it, it decided on secrecy and did not want the
public or the EPA to know of its efforts. Internal emails
within the company are alleged to have said that “for
many, many of our projects it would be a real disaster”
to have Dr. Cory-Slechta on the scientific advisory panel
and suggested to the lobbying firm that the EPA be told that
her scientific conclusions were “in reality, speculation”
and her statements “overly dogmatic.” A regulatory
expert at the lobbying firm also evidently communicated the
company's concerns to the EPA, omitted that the concerns actually
came from paraquat's manufacturer, and did so outside of the
public docket. Ultimately, the EPA did not choose Dr. Cory-Slechta
for the advisory panel but instead selected a scientist supported
by the lobbying firm.
These
attacks on a scientist and science are not limited to the
Parkinson's community but extend to investigators studying
the effects of other pesticides, air pollution, and greenhouse
gases. Without a response, companies will only be more emboldened
in their future efforts to discredit researchers conducting
work that may be contrary to their narrow, commercial interests.
Finally,
agnotology is an attack on the public health. Today, possibly
because of the spread of environmental toxicants like paraquat,
Parkinson's disease is the world's fastest-growing brain disease.
From 1990 to 2016 the number of people with the disease more
than doubled globally, far more than can be explained by aging
alone.15 Absent change, Parkinson's disease is poised to double
again in the coming generation. In the United States, the
incidence is likely increasing17 and may be 50% more than
previously estimated.18 According to the Global Burden of
Disease study, the three countries with the highest rates
of Parkinson's disease in the world are Canada, the United
States, and Argentina.15 Until 2022 when the manufacturer
of paraquat voluntarily discontinued its use in Canada, all
three allowed the spraying of the toxic weedkiller.
THE
COSTS OF AGNOTOLOGY
Agnotology is harmful and carries immense human, societal,
and scientific costs. Unknown numbers of farmers and possibly
many millions of rural residents globally have been exposed
to paraquat, which has likely helped fuel the increase in
Parkinson's disease in these communities. The resulting untold
death, disability, and suffering for more than 50? years were,
if the Guardian reporting is accurate, preventable.
Human
suffering should not be subservient to one corporation and
the revenue of its $400 million product. By comparison, Medicare
(the U.S. federal health insurance program for older adults)
alone spends about $25 billion annually caring for over 1
million Americans with the disease.20 The indirect costs of
care giving and disability increase the economic burden of
Parkinson's disease in the United States to over $50 billion,
20 more than 100 times what the chemical company reaps in
global sales from a 60-year-old pesticide. This is essentially
subsidizing corporate profit with human life. The result makes
no economic sense and is ethically repugnant. The subsidy
must end.
Agnotology
also affects the conduct of science itself. Scientific inquiry
is selective. Some questions are asked, whereas others are
left uninvestigated or under-investigated. This has happened
in Parkinson's disease. Since the company is believed to have
begun hiding the risks of its own chemical, studies analyzing
the genetics of Parkinson's disease, which has a low heritability
outnumber environmental studies by a factor of six. As Proctor
writes, “[Knowledge] switched onto one track cannot
always return to areas passed over; we don't always have the
opportunity to correct old errors. Research lost is not just
research delayed; it can also be forever marked or never recovered.”
REMEDIES
FOR AGNOTOLOGY
There are several antidotes to the doubt that chemical manufacturers
have generated. First, wrongdoers must be punished. The truth
about paraquat was revealed only as a result of lawsuits against
the manufacturer by large numbers of people who have alleged
they developed Parkinson's disease as a result of exposure
to the chemical. In addition to personal injury litigation,
regulatory agencies and governments must bring civil or criminal
actions against those who harm the public's health. Second,
the burden of proof of safety must shift to manufacturers.
This “precautionary principle” would mirror what
is required of drug manufactures who must demonstrate both
the efficacy and safety before medications are approved for
use. Third, the control of many regulatory agencies by the
interests they regulate (“regulatory capture”)
must end. According to the Guardian, one of the EPA officials
who signed off on the EPA's review of paraquat in 2019 belonged
to a “powerful Washington-based lobbying organization
that represents the pesticide industry.”
Finally,
we must investigate whether other inhaled toxicants, such
as pesticides, industrial solvents (eg, trichloroethylene),
and ambient air pollution, are fueling the growth of Parkinson's
disease. Such research might generate explanations for a wide
range of conditions beyond Parkinson's disease, including
other neurological (eg, amyotrophic lateral sclerosis and
Alzheimer's disease) and medical (eg, autoimmune diseases
and cancer) conditions. If a chemical company is able to hide
a pesticide's risk of Parkinson's disease, we must ask what
other businesses are doing about the environmental pollutants
that they manufacture or sell.
The
battle over paraquat, Parkinson's disease, and agnotology
is not over. In response to a recent lawsuit, the U.S. Department
of Justice has ordered the EPA to reevaluate its decision
to permit the continued use of the deadly weedkiller. Until
then, paraquat continues to be sprayed on farms across America
and globally and, along with it, the possible seeds of future
cases of Parkinson's disease.
