GLYPHOSATE - RealAgriculture
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
AUGUST 2018
SOME GOOD NEWS ABOUT
GLYPHOSATE
BY CHRISTOPHER P. DUFAULT, P.AG., AND
ROBERT SAIK, P.AG. CAC
These days we are exposed to a great deal time from the Ontario Ministry of Agriculture,
Food and Rural Affairs (OMAFRA) in Ontario,
of negative, one-sided and inaccurate
Canada. This data, collected using consistent
information in the media and online
methodology, enables us to learn more about
about a herbicide called glyphosate, often
how changing farming practices impact the
sold under the trade name Roundup. environment and those working in agriculture.
We interact with farmers and farm
In this article we'll talk about:
organizations on a regular basis. We
understand their concerns with economic the overall reduction in the amount of
sustainability and their interest in herbicide applied in Ontario corn and
environmental stewardship. And we soybean production;
understand the valuable contribution that
technological advances have made in the increased use of glyphosate and benefits
improving the sustainability of agriculture. Now, versus other herbicides displaced by
agenda-driven groups seek to take one of glyphosate;
agriculture’s most useful technologies,
glyphosate, and end its use through well- the reduced hazard and risk from the use of
orchestrated, alarmist misinformation glyphosate, based on indicators called the
campaigns. environmental impact quotient (EIQ) and
environmental impact (EI), respectively; and
But what do government surveys and regulatory
decisions tell us? To understand the real story the positive reassessments of the safety of
we turn to an excellent set of data that tracks glyphosate by the world’s major pesticide
trends in pesticide use, hazard and risk, over regulators.SOME GOOD NEWS ABOUT GLYPHOSATE PAGE 2
USE OF HERBICIDES INCLUDING kg ai all herbicides acreage kg ai glyphosate
GLYPHOSATE IN ONTARIO 4,000,000
3,500,000
Every five years, for the past several decades,
3,000,000
Ontario has surveyed farmers on their use of
2,500,000
pesticides including herbicides, insecticides
2,000,000
and fungicides. The most recent survey dates
1,500,000
from 2013-2014 (1). Today, we are focusing on
what this survey tells us about trends in the 1,000,000
use of herbicides in corn and soybeans in 500,000
Ontario. 0
1983 1988 1993 1998 2003 2008 2013
CORN Figure 1. Amount of herbicide applied to field corn and
acreage grown in Ontario from 1983 to 2013. Drawn
Between 1983 and 2013, the total amount of
from OMAFRA data (1) by Dufault & Saik.
herbicide used in field corn in Ontario declined
by 39% (Figure 1). This reduction is primarily due
to the increased use of glyphosate, which is yield (bu/acre) kg ai all herbicides/10,000 bu
applied at a lower rate of active ingredient (ai) 200
per acre than the herbicides it replaced, 175
increasing from 1% to 54% of the amount of all 150
herbicides applied to field corn during that 125
period. Furthermore, the decline in the total 100
amount of herbicide applied occurred despite 75
an 11% increase in the area grown to field corn 50
(Figure 1). 25
0
1983 1988 1993 1998 2003 2008 2013
In that same 30-year period, the yield per acre
of field corn increased by 74% (Figure 2). And
due to a combination of the reduced amount of Figure 2. Yield of field corn and amount of herbicide
applied per 10,000 bushels in Ontario from 1983 to
herbicide applied per acre and increased yield,
2013. Drawn from OMAFRA data (1) by Dufault & Saik.
the amount of kg ai of all herbicides applied per
bushel produced declined by a whopping 70%
(Figure 2).
Report prepared by Dufault and SaikSOME GOOD NEWS ABOUT GLYPHOSATE PAGE 3
yield (bu/acre) kg ai all herbicides/1,000 bu
SOYBEANS
50
Soybeans are also a good news story. Between
1983 and 2013, despite the acreage of soybean 40
grown in Ontario increasing by a massive 188%, 30
the total amount of herbicide applied
20
increased by just 47% (Figure 3). As with field
corn, this is largely due to the replacement, by 10
glyphosate, of other higher-rate herbicides;
0
usage of glyphosate increased from 2% to 82%
1983 1988 1993 1998 2003 2008 2013
of all herbicides applied during that timeframe
Figure 4. Yield of soybean and amount of herbicide
(Figure 3).
applied per 1,000 bushels in Ontario from 1983 to 2013.
Drawn from OMAFRA data (1) by Dufault & Saik.
In that same 30-year period, the yield of
soybean increased by 53% (Figure 4). And the AGRONOMIC BENEFITS OF GLYPHOSATE
amount of kg ai of all herbicides applied per
From an agronomic perspective, glyphosate has
bushel produced declined by an impressive been referred to as a “once-in-a-century
67% (Figure 4). herbicide” (2). Being a broad-spectrum herbicide,
it controls virtually all species of weeds and has
been utilized mostly in conjunction with
kg ai all herbicides acreage kg ai glyphosate herbicide-tolerant crops since their first
3,000,000 appearance in the mid-1990s. Glyphosate
2,500,000 also largely eliminates the need for several
applications of multiple limited-spectrum
2,000,000
herbicide active ingredients that would otherwise
1,500,000
be needed to control all the species of weeds
1,000,000 present. Not only do these other herbicides
500,000 generally have higher hazard/risk profiles
0
(discussed below), but they are often more
1983 1988 1993 1998 2003 2008 2013 phytotoxic. The resultant crop damage reduces
yields unlike when glyphosate is used in
Figure 3. Amount of herbicide applied to soybeans herbicide-tolerant crops. Economists have
and acreage grown in Ontario from 1983 to 2013. estimated that if the world ceased to grow
Drawn from OMAFRA data (1) by Dufault & Saik.
genetically-modified herbicide-tolerant crops in
the absence of glyphosate, the annual loss of farm
income would be $6.76 billion and there would
be substantial declines in the production of
soybean, corn and canola (3).
Report prepared by Dufault and SaikSOME GOOD NEWS ABOUT GLYPHOSATE PAGE 4
The widespread adoption of glyphosate has also Different ways of calculating an EIQ are found in
resulted in decreased tillage (or soil cultivation) the published literature. The particular EIQ used
as farmers have adopted minimum or zero by Ontario in this study is calculated based on
tillage growing systems. This has profound data taken from 12 different data points from
implications because reduced tillage means safety tests conducted on pesticides in the
lower greenhouse gas emissions from burning laboratory and the field. Briefly, these include
less fossil fuel as well as from reduced measures of short- and long-term toxicity in
decomposition of organic matter in the soil. laboratory animals, half-life, whether systemic in
Additionally, the associated increase in soil tilth plants (i.e., tendency to circulate through plant
brings better water holding capacity and tissues), leaching and runoff potential, and
increased soil health. toxicity to several species of non-target
animals.
ENVIRONMENTAL IMPACT QUOTIENT (EIQ)
AND ENVIRONMENTAL IMPACT (EI) OF The reported EIQ for glyphosate was calculated
GLYPHOSATE to be just 15.3 which is the tenth lowest EIQ of
all the pesticide active ingredients from the
Based on the data just cited, it is apparent that
survey. Furthermore, glyphosate has partially
the amount of herbicide used to produce field
replaced the use of herbicides with higher EIQs,
corn and soybeans in Ontario has declined due
including atrazine (EIQ = 22.9) in corn, and
to glyphosate largely replacing other major
metolachlor/s-metolachlor (EIQ = 22.0) in corn
herbicides that are applied at higher rates.
and soybeans, meaning it is less hazardous than
these herbicides. This low EIQ for glyphosate is
But, does a lower rate of application also mean
not surprising, considering that it is “less acutely
reduced risk?
toxic than common chemicals such as sodium
chloride (salt) or aspirin” (2).
In conjunction with the results of the pesticide
use survey, Ontario also published a report on
So, what about risk? This can be called
the environmental risk associated with pesticide
environmental impact (EI) and is essentially
use in Ontario (4). This report used an
hazard (EIQ) multiplied by exposure (i.e.,
Environmental Impact Quotient (EIQ) to
amount used). Not only does glyphosate have a
estimate the hazard associated with the use of
lower EIQ than the above-mentioned major
each pesticide recorded in the survey.
herbicides that it replaces, but it is also
Essentially, the EIQ is an indicator of the
recommended in Ontario for application at a
potential of a pesticide to cause harm. The EIQs
lower rate per acre than the other herbicides
for different pesticides can be compared and
when applied on their own (5). Whereas, the
the higher the EIQ value, the greater the
Ontario study (4) calculated EIs for the use
possible harm such as to farm workers,
of glyphosate in the whole province, we have
consumers and ecosystems.
Report prepared by Dufault and SaikSOME GOOD NEWS ABOUT GLYPHOSATE PAGE 5
done so on a per acre basis. The combination of
This report has engendered much controversy
factors – lower EIQ and lower rate – means the EI
as evidenced by the many, contrasting points of
for glyphosate per acre of field corn, for
view on the subject that can be found on the
example, is about 60% less than for the major
internet. We will simply say the following:
herbicides that it replaces (Figure 5).
The IARC report took account only of
published toxicity data on glyphosate.
erca rep )IE( tcapmi latnemnorivne
16
14 The IARC report was a hazard assessment
12 and did not include a health risk assessment
10 that would take account of how glyphosate is
8 used. Remember: hazard x exposure = risk.
6
4 The pesticide regulators in each country in
2 which glyphosate is registered have access to
0 much more substantial and relevant data sets
glyphosate atrazine metolachlor / than does IARC. For example, in addition to
s-metolachlor
reviewing and validating published data,
Figure 5. Environmental impact (i.e., risk) per acre of
these organizations also review the extensive
glyphosate and two other herbicides in field corn in
body of toxicology studies from registrants
Ontario. Source data: EIQs from OMAFRA (4) x
recommended rates in Ontario of these herbicides that are conducted using internationally-
applied on their own (5). Drawn by Dufault & Saik. accepted protocols. These latter studies are
also required to meet stringent Good
Laboratory Practice (GLP) guidelines such as
REGULATORY STATUS OF GLYPHOSATE those of the Organization for Economic Co-
operation and Development (OECD) (7).
So, all the above is good news for producers and
the environment. But it’s fair to say that the 12
Regulatory agencies update their reviews of
data points used in estimating the EIQ are taken
all registered pesticides at regular intervals;
from a fraction of all the health and
Canada and the USA do so every 15 years. And
environmental studies done to assess the safety
virtually all the pesticide regulatory agencies
of pesticides. And, there’s the 2015 report from
in the world, that have recently updated their
the International Agency for Research on
reviews of glyphosate, have reconfirmed its
Cancer (IARC) of the World Health Organization
safety and renewed its registration, in
(WHO) that classified glyphosate as “probably
contrast to IARC’s assessment of glyphosate
carcinogenic to humans” (6).
as being “probably carcinogenic to humans.”
Report prepared by Dufault and SaikSOME GOOD NEWS ABOUT GLYPHOSATE PAGE 6
Here’s a small sampling of what some of these CONCLUSIONS
regulatory agencies have published:
While both corn and soybean acreage AND yield
have increased in Ontario since 1983, the overall
In March 2017, the European Chemicals environmental impact of herbicide use per acre
Agency reported their determination that has declined in large part because glyphosate
glyphosate is not classified as a carcinogen has displaced other more harmful major
(8). herbicide chemistries.
In its draft “Revised Glyphosate Issue Paper: This reduction in risk is due to 1) glyphosate
Evaluation of Carcinogenic Potential” being less hazardous, based on the EIQ,
document for public comment dated compared with these other herbicides, and 2)
December 12, 2017, the US Environmental glyphosate being applied at a lower rate. Major
Protection Agency stated that it had regulatory agencies, such as Canada’s PMRA,
reviewed close to 170 epidemiological, animal have recently reconfirmed the safety of
carcinogenicity and genotoxicity studies, and glyphosate and renewed its registration.
that the available data do not support a
carcinogenic process for glyphosate (9). Glyphosate has played a key role in enabling
many farmers to achieve excellent weed control
On April 28, 2017, Canada’s Pest Management in herbicide-tolerant crops while adopting
Regulatory Agency (PMRA) reported in its reduced or zero tillage. This reduction in
completed re-evaluation of glyphosate that it cultivation has positive implications for the
is “unlikely to pose a human cancer risk.” In environment in terms of soil health, water
explaining why PMRA’s conclusions differed holding capacity and greenhouse gas balance.
from those of IARC, PMRA stated “. . . the level
of human exposure, which determines the
actual risk, was not taken into account by
IARC (10). PMRA renewed the registration of
glyphosate in Canada with only minor label
changes.
Christopher P. Dufault is a Professional Agrologist, and the former head of the Re-evaluation and Use Analysis
Section of the Pest Management Regulatory Agency in Canada. Currently, he is a Senior Agri-Coach with Agri-Trend
and Principal of Christopher P. Dufault & Associates Inc., based in Ottawa, Ontario, Canada.
Christopher.dufault(at)cantab.net. Robert Saik, a Professional Agrologist and Certified Agricultural Consultant, is the
founder of Agri-Trend and Principal of Saik Management Group Inc., based in Olds, Alberta, Canada.
Rob@RobertSAIK.com 403-391-0772. Neither has ever worked for any manufacturer of glyphosate.SOME GOOD NEWS ABOUT GLYPHOSATE PAGE 7
REFERENCES
1. Farm & Food Care Ontario. 2015. Survey of 6. IARC Monographs Volume 112: evaluation of
Pesticide Use in Ontario, 2013/2014. Estimates of five organophosphate insecticides and
Pesticides Used on Field Crops and Fruit and herbicides. 2015. https://www.iarc.fr/en/media-
Vegetable Crops. centre/iarcnews/pdf/MonographVolume112.pdf
http://www.farmfoodcareon.org/wp-
content/uploads/2016/10/ONTARIO-Pesticide- 7. Good Laboratory Practice (GLP).
Use-Survey-Final-2013.pdf http://www.oecd.org/chemicalsafety/testing/go
od-laboratory-practiceglp.htm
2. Duke, Stephen O. and Stephen B. Powles.
2008. Mini-review. Glyphosate: a once-in-a- 8. Glyphosate not classified as a carcinogen by
century herbicide. Pest Management Science. ECHA. 2017. https://echa.europa.eu/-/glyphosate-
64: 319-325. not-classified-as-a-carcinogen-by-echa
https://naldc.nal.usda.gov/download/17918/PDF
9. Revised Glyphosate Issue Paper: Evaluation of
3. Brookes, Graham, Farzad Taheripour and Carcinogenic Potential. 2017.
Wallace E. Tyner. 2017. The contribution of https://www.regulations.gov/document?D=EPA-
glyphosate to agriculture and potential impact HQ-OPP-2009-0361-0073
of restrictions on use at the global level. GM
Crops & Food. Biotechnology in Agriculture and
10. Re-evaluation Decision RVD2017-01,
the Food Chain. 8: 4: 216-228.
Glyphosate. 2017.
https://www.tandfonline.com/doi/full/10.1080/21
https://www.canada.ca/en/health-
645698.2017.1390637
canada/services/consumer-product-
safety/reports-publications/pesticides-pest-
4. Van Eerd, Laura L. 2016. Environmental Risk of
management/decisions-updates/registration-
Pesticide Use in Ontario: 2013/2014 Pesticide Use
decision/2017/glyphosate-rvd-2017-01.html
Survey. http://www.farmfoodcareon.org/wp-
content/uploads/2016/10/EIQSurvey2013FINAL.p
df
5. Publication 75A Guide to Weed Control. Field
Crops. 2018 [OMAFRA].
http://www.omafra.gov.on.ca/english/crops/pub
75/pub75A/pub75A.pdfYou can also read
