GMO Myths and Truths

5.6 Myth: Roundup is a benign and biodegradable herbicide
Truth: Roundup persists in the environment and has toxic
effects on wildlife
Manufacturers claim that Roundup, the
glyphosate-based herbicide used on most GM
crops, breaks down quickly and harmlessly in
the environment. But research shows that this is
untrue:
● In soil, glyphosate has a half-life (the length of
time taken to lose half its biological activity)
of between 3 and 215 days, depending on soil
conditions. 85,86 In water, glyphosate’s half-life is
35–63 days. 87
● Although glyphosate binds well to soil particles,
the Danish National Pesticide Monitoring
Program showed that glyphosate and its main
breakdown product AMPA are washed out of
the root zone of clay soils in concentrations
that exceed the acceptable quantities for
drinking water (0.1 μg/l), with maximum values
of over 5 μg/l. 88
● Glyphosate was detected in between 60 and
100% of air and rain samples taken in the
American Midwest during the crop growing
season in the American Midwest, where
Roundup Ready GM crops are widely planted. 89
● Glyphosate and its main breakdown product,
AMPA, were detected in streams in the
American Midwest during the crop growing
season. 90
● Glyphosate is toxic to earthworms 91 and
reduces bird populations due to habitat
changes. 92
● Roundup is highly toxic to amphibians. A
study in a natural setting found that Roundup
application at the rate recommended by
the manufacturer eliminated two species of
tadpoles and nearly exterminated a third
species, resulting in a 70% decline in the species
richness of tadpoles. Contrary to common
belief, the presence of soil does not reduce the
chemical’s effects. 93 Further experiments with
lower concentrations, well within levels to be
expected in the environment, still caused 40%
amphibian mortality. 94
● Claims that Roundup and glyphosate are
safe for human health and the environment
have been overturned in courts in the United
States 95 and France. The French court forced
Monsanto to withdraw advertising claims that
Roundup is biodegradable and leaves the soil
clean after use. 96
Regulatory bodies around the world have not
caught up with the state of the science on
Roundup and glyphosate. Instead they continue
to rely on decades-old studies, mostly sponsored
by manufacturers, to claim it is safe. An objective
up-to-date review of Roundup and glyphosate’s
persistence and toxicity is long overdue.
GMO Myths and Truths 81