Title: Glyphosate is being reviewed in the United States and Canada. Is it still safe to use?
[APVMA 'Community Question' 31 August 2010] Yes. The current international
consensus based on decades of research and evaluation is that glyphosate remains
a safe and effective chemical when used according to label
instructions. The United States Environmental Protection Agency
(USEPA) and the Canadian Pest Management Regulatory Agency (PMRA) have recently
commenced routine re-registration reviews of glyphosate. Both these regulators
have indicated that they will use these reviews to consider new research about
glyphosate, including new studies relating to potential environment and health
risks.
About glyphosate
Glyphosate is a broad spectrum, non-selective herbicide widely used for the
control of annual, perennial, brush and woody weeds.
It is absorbed by plant foliage and green stems and moves through the plant
from the point of contact to and into the root system.
The herbicide was developed in the 1970s and was registered for use in
Australia by state and territory authorities not long afterwards.
In the mid 1990s it was reassessed by the National Registration Authority
(the precursor to the Australian Pesticides and Veterinary Medicines Authority
(APVMA)) and granted registration following the consideration of relevant
scientific information.
Currently there are over 300 glyphosate products registered in Australia for
use in croplands, industrial and commercial areas, aquatic areas, forests and
plantations and in the home garden.
Glyphosate is used extensively around the world and has been reviewed by a
number of international expert bodies and regulatory agencies since it was first
registered.
How do we know it is still safe?
There have been many scientific assessments of glyphosate around the world
since the first Australian registrations. In 1994, for example, the U.S. EPA
conducted a review of glyphosate and found few issues of concern. The human
risk assessment found that human dietary exposure and risk were minimal and that
exposure to workers and other applicators were generally not expected to pose
undue risks. Its ecological risk assessment concluded that the effects of
glyphosate on birds, mammals, fish and invertebrates were minimal.
The USEPA did find, however, that an inert ingredient in some glyphosate
formulations was toxic to some aquatic life and required changes to glyphosate
product labels to protect aquatic organisms. Additional label changes to update
worker protection requirements and establish entry restrictions were made.
Two years later in 1996, the APVMA reviewed
glyphosate products because of evidence that it was toxic to frogs and
tadpoles when applied in or adjacent to aquatic areas. Research subsequently
determined that the toxicity was due to particular surfactants (members of the
polyethoxylated amine family) in the glyphosate formulations that were
registered at the time. These were some of the ‘inert ingredients’ identified by
the USEPA in its review. The APVMA consequently prohibited the use of glyphosate
on and near waterways until such time as new formulations with different
surfactants that were not toxic to aquatic life could be developed and
registered. Today, over a third of all registered glyphosate products contain
these new surfactants and can be used in or adjacent to waterways.
Thus when the European Union
formally assessed glyphosate in 2002, it was consistent with the scientific
literature of the time when it found that glyphosate is neither genotoxic or
carcinogenic, and has no relevant neurotoxic, reproductive or endocrine
disruption effects. The review also contained an extensive assessment of its
environmental fate. It notes that there was a comprehensive set of studies to
support glyphosate registration in the EU.
New risks?
In the last few years a number of studies have emerged linking glyphosate and
common surfactants in glyphosate products (such as polyethoxylated amines) and
metabolites such as amino methyl phosphonic acid (AMPA) to human health and
environmental issues. This research has recently been brought together in
a
monograph by the Pesticide Action Network Asia and the Pacific. Researchers
conducting in vitro (test tube) studies, for example, have argued that
glyphosate affects progesterone production in mammalian cells and can increase
the mortality of placental cells. Furthermore environmental groups have recently
argued that a specific polyethoxylated amine surfactant (POEA) poses risks to
aquatic animals.
Some national regulators have already considered some of these issues. In
August 2009 the Canadian
PMRA assessed a number of in vitro studies suggesting POEA
formulants in certain glyphosate products represented a risk to human health. It
found that these studies were not representative of what occurs with in vivo
exposure of living organisms. It also concluded that data presented in a
submitted epidemiology study purporting to show an important relationship
between glyphosate exposure and spontaneous abortion was not valid due to
unvalidated self reported exposure information, a lack of controls, and
potentially confounding factors such as maternal age.
However, both the USEPA and the PMRA initiated routine scheduled
re-registration reviews of glyphosate in mid 2009 and early 2010 and both will
formally consider this and any other new evidence. An identified focus of the
EPA review, for example, will be a consideration of the ecological risk posed by
amino methyl phosphonic acid (AMPA), a degradation product of glyphosate.
Another will be an assessment of the surfactant polyethoxylated tallow amine
(POEA).
The
Canadian review, while more general in scope, will be closely aligned to the
USEPA re-registration review. A specific focus is a health and an environmental
risk assessment of the POEA/glyphosate combination.
The Australian position
The APVMA currently has no data before it suggesting that glyphosate products
registered in Australia and used according to label instructions present any
unacceptable risks to human health, the environment and trade. Accordingly, the
APVMA will monitor the US and Canadian reviews of glyphosate and consider any
new evidence that emerges.