So today what we're going to do, is
we're going to talk risk versus hazards
and how that plays into the IARC, FAO, and EPA findings
around glyphosate.
This all ties in to you at home, but understanding
these findings around this topic is fairly important.
So let's start with a few definitions.
So hazard, also called toxicity, is a measure of a substance
ability to cause harm.
So hazard is an inherent property
of the substance itself.
It is immutable and unchangeable.
So if a chemical is corrosive to the eyes,
it will damage your eyes on contact, plain and simple.
Risk, on the other hand, is how likely
it is that substance will cause harm
at expected exposure levels.
This estimate depends both on the substance hazard
and your level of exposure to the substance.
So if you wear protective goggles
when handling a chemical that is corrosive to your eyes,
you will greatly reduce your risk of eye damage.
So hazard is asking, can it cause harm,
while risk is asking, will it cause harm
at expected exposures.
This is really important for this entire talk.
So this yields what we call the risk equation.
And that basically states that risk equals hazard times
exposure.
So you'll never hear me say that a chemical is safe,
because that implies there's zero risk.
All chemicals pose a risk at some level of exposure.
Since neither hazard nor exposure is zero,
simple math says, risk can't be zero either.
But risk can be very low or very high
depending on the level of hazard of the chemical
and the level of exposure to that chemical.
So unlike hazard, risk is a mutable property.
And we can manage it.
We can reduce our risk by being smart,
but we can also increase our risk by being foolish.
So for a common real-life example of hazard versus risk,
let's consider a bottle of Tylenol
and a story of two doctors.
The active ingredient in Tylenol is acetaminophen.
And as you can see, it has lots of uses.
Acetaminophen is great stuff, but toxicological studies
have shown that high doses of it can
be toxic to your liver, cause liver failure and even death.
That is the hazard associated with acetaminophen.
Notice on the label it says that damage
may occur if you take over a certain amount,
and it also tells you not to take the other drugs containing
acetaminophen at the same time.
These statements are both about exposure.
And then if you look at infant or children's Tylenol,
you'll notice that the dose is drastically reduced.
That's because children are smaller than adults,
and it takes a smaller dose, or a smaller exposure,
not only to be effective but also
to cause harm to the liver.
And then if we look at the use directions right on the bottle,
they show you how to avoid exposure.
Additionally, medical studies have
been conducted that show that the dose, or exposure suggested
on the label is high enough to alleviate headaches and fever,
but not high enough to cause liver damage.
So if we take this to the tale of two doctors.
We have two doctors seeing two children
of similar ages, similar weights,
and they both exhibit a fever.
So one doctor, Dr. Smith, is asked
can Tylenol harm the liver.
And Dr. Smith answers, yes, it can.
Meanwhile in another room, Dr. Jones is being asked,
will that dose of Tylenol harm the liver.
Excuse me-- to which Dr. Jones answers, it is highly unlikely.
So we got one doctor saying yes, it can harm the liver.
We have one doctor saying, it's highly unlikely
that it will harm the liver.
So the big question is, which one of them
is incompetent, which one of them
in the pocket of big pharma.
Who's doing it wrong?
As you may guess, it's neither.
Mother one simply asked a question
about the hazard associated with Tylenol,
and Dr. Smith answered honestly because science
shows that acetaminophen can cause liver damage
at some level of exposure.
Mother two, on the other hand, asked about the risk
associated with taking Tylenol.
And Dr. Jones answered honestly because science
shows that the liver damage is highly unlikely when
Tylenol is used as a directive.
So that's risk versus hazard in a acetaminophen
or a Tylenol situation.
So what does this all have to do with glyphosate?
Well, the Inter Agency of Research on Cancer,
or the IARC, which is under the UN's World Health
Organization in March 2015 issued this monograph
in which they listed glyphosate as a probable group
to a human carcinogen I assume most of you are aware
of these findings and have heard about it in the news.
To be clear, the IARC committee was made up
of qualified scientists who looked
at a boatload of scientific studies on the subject
and produced a science based consensus.
The classification as a probable carcinogen
was largely based on concerns around non-Hodgkin's lymphoma
cancer.
So given these findings from the IARC,
the logical question is, why is glyphosate
still being sold and used worldwide,
and why hasn't the EPA banned it.
To find out the answer, you only have
to go to the preamble of the same IARC monograph.
And in the preamble of that monograph, they state,
"A cancer hazard is an agent that
is capable of causing cancer under some circumstances,
while a cancer 'risk' is an estimate of the carcinogenic
effects expected from exposure to a cancer hazard."
So that opening statement from the IARC
is basically reconfirming that risk is
based on hazard times exposure.
The passage continues, "The distinction between hazard
and risk is important, and the Monographs
identify cancer hazards even when
risks are very low at current exposure levels."
Did any of you ever hear about the preamble
of this monograph in any of the news
that you heard, in this widely reported on monograph?
You didn't hear about it in the news
because it mostly didn't make the news, except on NPR.
Excuse me-- so on NPR, they interviewed Dr. Aaron Blair,
and he's the chair of the IARC committee.
Dr. Blair is with the National Cancer Institute
and has been studying pesticides in cancers for over 40 years.
And in that interview, Dr. Blair said the agency asks,
"can glyphosate cause cancer in some circumstances
at some level of exposure?"
Additionally, he reaffirmed that the IARC does not
ask how common such circumstances or exposures
occur in the real world.
That question is what is the risk,
and the IARC is looking at hazard or toxicity.
So the IARC only looked at hazard,
and they found it to be a probable carcinogen.
So if the IARC doesn't ask about risk, then who does
ask about risk?
A couple of people do.
Well, lots of people, a couple of big agencies.
So the joint FAO and WHO are the IARC's parent agency.
The WHO and the UN Food and agricultural Organization
ask this very question.
And they reported that glyphosate
is unlikely to pose carcinogenic risks from dietary exposures.
So two agencies, the WHO and the UN Food and Agricultural
organizations both came together and put out
a publication stating that glyphosate
is unlikely to pose a carcinogenic
risk in dietary exposures.
Additionally, the EPA asked this question about risk.
And the EPA asked the question of risk
from the point of view of application of the pesticide.
And its findings and its draft evaluation
of glyphosate's carcinogenic potential
was that the strongest support was for "not likely
to be a carcinogen at doses relevant to human health
risk assessment."
So both FAO, WHO, and EPA findings, these
both came after the IARC report was out.
So that widely reported probable carcinogen monograph,
these both came out after that.
Their analysis were also conducted
by qualified scientists who looked at boatloads
of scientific studies on the subject
and produced a science based consensus.
So why are the FAO and EPA saying glyphosate is not
likely to be carcinogenic when the IARC is saying it's
a probable human carcinogen?
The key once again, just like the Aspirin example,
is they're asking two very different questions.
The FAO and EPA are asking about risk,
while the IARC is asking about hazard.
So let's talk about the non-Hodgkin's lymphoma
side of this real quickly.
Some full disclosures, these coming slides,
they were produced by Dan Wixted,
who's a well respected pesticide safety educator.
To be clear, Dan is not a cancer researcher.
He is a bug guy and a safety educator.
So what he did to make sure that his slides and script were
accurate, is he sent them to Aaron Blair,
that guy who's the chair of the IARC committee.
And then during a follow up phone conversation,
Aaron mentioned some ways that Dan could improve his accuracy.
So everything in these next slides with the Cornell
branding on them is from Dan and it was vetted by Dr. Blair.
And for reasons including respect and accuracy,
I'm going to generally follow Dan's script
with only minor modification for the next few slides.
So remember the EPA'S draft assessment said,
glyphosate was not likely to be carcinogenic at doses
relative to human health.
That draft was by the agency itself, the EPA, and then
the EPA's independent scientific advisory panel reviewed it,
and some members of that panel disagreed
with the EPA's analysis.
Most of their disagreements were centered around occurrences
of non-Hodgkin's lymphoma, which was also
a big factor in the IARC's findings, as you may recall.
One claim that Dan came across numerous times in his research,
was that incidences of non-Hodgkin's lymphoma
had doubled since glyphosate came on the market in 1974.
So this led to a little more investigation
by Dan and some interesting data.
So according to data from the National Cancer Institute,
the incidence-- pardon me-- of non-Hodgkin's lymphoma
indeed did double almost from 75 to 95,
from nearly 11 new cases per 100,000 people per year
to 20 new cases per 100,000 per year.
And according to EPA data, during that time period,
glyphosate use also increased about 20-fold.
So with these two curves tracking nearly parallel,
people started suggesting that this correlation showed
a causal relationship.
We'll get back to correlation and causation in a little bit,
but let's just keep moving.
So they suggested this correlation was causation.
So is glyphosate the major driver
for non-Hodgkin's lymphoma?
There was a study conducted by the University of Rochester
that showed three factors were found
to account for 50% of the increase in non-Hodgkin's
lymphoma from the graph I just showed you.
So obviously, improved cancer reporting and changes
in classification to include more types of cancer
are going to increase your numbers.
And then a new type of associated lymphoma showing up
also likely to increase your numbers.
Now that's only 50% of the increase.
The other 50%, the reason behind that, is unclear.
But exposure to environmental toxins, such as pesticides,
might be a contributor.
The authors just couldn't say for sure in their study.
So if we go back to the National Cancer Institute and the EPA
data, we see that correlation suggesting
a possible carcinogenic effect.
So the question becomes, what happened over the next 20
years.
So here we have a vertical line, which
indicates 1995, which is the year
before Roundup Ready crops came to the market.
Following that, to no one's surprise,
annual glyphosate use skyrocketed once those crops
came on the market.
So use skyrocketed once they came
on the market from less than 50 million pounds
annually to nearly 300 million pounds annually.
Meanwhile, the non-Hodgkin's lymphoma rates
have leveled off around 20 new cases per 100,000 per year.
Now, does this mean glyphosate is not
contributing to non-Hodgkin's lymphoma
in the general population?
Not necessarily.
All we can really know from this data,
is that even if glyphosate exposure can
cause non-Hodgkin's lymphoma in some people
under some circumstances, it's not
the major driver in non-Hodgkin's lymphoma rates
in the general population.
If it was, the red line would be increasing along
with that blue line.
The data in this graph is also consistent with other studies
that have looked for connections between glyphosate exposure
and non-Hodgkin's lymphoma.
Importantly, these studies, these other studies
that support this graph, focus specifically
on applicators who experience the greatest exposure, not
the general public.
So if anyone is at risk to get cancer
from glyphosate exposure, it's going
to be that occupational user.
And that's who they focused on, and they found no evidence
supporting that claim either.
In revisiting its findings on the carcinogenic potential
of glyphosate, one thing that the EPA
looked at in their review was the National Institute
of Health's AG Health Study.
I believe this is the largest and longest
epidemiological study involving pesticide applicators
and their spouses, which gives its findings
a quite a bit of weight.
And the study has been tracking participants, pesticide use,
and health histories for over 25 years.
And as you can see, it's 56,000 plus applicators
and 32,000 plus spouses.
In 2005, a peer reviewed paper was
published from this research, and it
found no statistically significant association
with glyphosate use or exposure in any cancer,
including non-Hodgkin's lymphoma.
This study was co-authored by Doctor Blair from the National
Cancer Institute.
And then in late 2017, there was a follow up
study that also came out.
And it came to the same conclusions,
which again, helped the EPA reaffirm its conclusion
that glyphosate is unlikely to pose a carcinogenic risk
at expected levels of exposure.
What the AG Health Study did find,
is an association between glyphosate use, and exposure,
and wheezing in farmers, and rheumatoid arthritis
in the spouses of applicators.
Now to be clear, an association also does not equal causation.
But it is a stronger indicator than a correlation,
and it points to areas that warrant more research.