Backgrounder
Glyphosate and Reproductive Toxicology
September 2002
Monsanto Company
Regulatory authorities and independent experts around the world agree that glyphosate does not
cause adverse reproductive effects in adults or birth defects in offspring of these adults exposed to
glyphosate, even at very high doses. This conclusion is based on multiple studies in laboratory
animals that have been conducted to examine the potential for such effects. These include studies in
which laboratory animals, their offspring and the next generation of offspring have been examined for
adverse effects.
An international panel of renowned toxicologists reviewed the extensive data for glyphosate (Williams
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et al., 2000). They concluded that the normal use of the original Roundup herbicide 鈥渄oes not result
in adverse effects on development, reproduction, or endocrine systems in humans and other
mammals.鈥? The World Health Organization (WHO 1994), the U.S. Environmental Protection Agency
(US EPA 1993, 1997) and the European Commission (2002) also have reviewed the data and
concluded that the use of glyphosate according to label directions would not result in adverse
reproductive or developmental problems or birth defects.
The U.S. EPA has evaluated glyphosate data according to parameters established by the Food Quality
Protection Act of 1996, which required special consideration of potential effects of pesticide use on
children. The U.S. EPA (1997) concluded that 鈥渢here is reasonable certainty that no harm will occur to
infants and children from aggregate exposure to glyphosate鈥?. The following in vivo (live animal) toxicology
studies have been conducted and reviewed by regulatory authorities, other scientific bodies and
independent experts:
Three-Generation Rat Reproduction: Male and female rats were fed glyphosate at dosages of 0, 3, 10,
and 30 mg/kg/day everyday throughout the production of three successive generations. No adverse
treatment-related effects on reproduction were observed. Likewise, there were no other adverse
effects as determined by gross and microscopic pathology examinations.
Two-Generation Rat Reproduction: Male and female rats were fed glyphosate at dose levels of 0, 2000,
10,000 and 30,000 parts per million (ppm; equivalent to approximately 0, 100, 500 and 1500 mg/kg
body weight/day) everyday throughout the production of two successive generations. It was concluded
that reduced body weights and soft stools occurred at 30,000 ppm (a very high dose representing
approximately 3 percent of the diet). Glyphosate did not affect the ability of rats to mate, conceive,
carry or deliver normal offspring at any dose and no treatment-related effects were seen at 10,000
ppm (1 percent of diet) and below.
Rat Teratology: No birth defects were observed in the offspring of pregnant rats given glyphosate by
gavage at dose levels of 0, 300, 1000, and 3,500 mg/kg/day on days 6 through 19 of gestation. Only
the highest dose caused adverse effects in the parent. No adverse effects were seen in either the
parent or the offspring at 1,000 mg/kg/day.
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鈥淩oundup鈥? refers to the original single active ingredient Roundup herbicide formulation (also known as MON
2139).
Backgrounder: Glyphosate and Reproductive Toxicology. 2002. Page 1 of 2
Rabbit Teratology: No birth defects were observed in the offspring of pregnant rabbits given glyphosate
by gavage at dose levels of 0, 75, 175 and 350 mg/kg/day on days 6 through 27 of gestation. Only the
highest dose caused adverse effects in the parent.
Wildlife studies:
In reproduction studies with bobwhite quail and mallard ducks, glyphosate was fed to male and female
birds at dietary concentrations of 0, 50, 200 and 1,000 ppm for 16-17 weeks. There was no effect on
reproductive success in either species at any dose tested.
In a chronic fathead minnow study, fish were exposed to glyphosate concentrations of 0.7, 2.8, 7.0.
13.0 and 25.7 mg/l for 255 days. No treatment-related effects were reported on the survival, growth
and egg production of first generation fish or on hatchability, survival and growth of second-generation
eggs and fry.
In summary, the results of these studies indicate that glyphosate does not produce birth defects and is not
a reproductive toxin.
Williams et al. (2000) also evaluated these studies to determine if glyphosate use had the potential to
adversely affect the function of endocrine systems. They evaluated the active ingredient (glyphosate),
its primary breakdown product (AMPA, aminomethylphosphonic acid), the original Roundup
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herbicide , and the polyethoxylated tallowamine (POEA) surfactant in the original Roundup herbicide .
The authors concluded:
鈥淭he endocrine-modulating potential of glyphosate has been evaluated in a variety of
studies including in vitro assays and standard in vivo toxicology studies. The in vivo
studies comprehensively assess endocrine functions that are required for reproduction,
development, and chronic health. Glyphosate produced no effects in in vitro assays, and
there was no indication of changes in endocrine function in any of the in vivo studies.
Results from standard studies with AMPA, Roundup herbicide, and the POEA surfactant
also failed to show any effects indicative of endocrine modulation. Therefore, it is
concluded that the use of Roundup herbicide has no potential to produce adverse effects
on endocrine systems in humans nor in other mammals.鈥?
The U.S. EPA (1997) also concluded that there are no significant findings in other relative toxicity
studies (i.e., teratology and multigeneration reproduction studies) which would suggest that
glyphosate produces endocrine effects.
References
European Commission (2002) Report for the Active Substance Glyphosate, Directive 6511/VI/99, Jan. 21.
http://europa.eu.int/comm/food/fs/ph_ps/pro/eva/existing/list1_en.htm
U.S. EPA (1993) Reregistration Eligibility Decision: Glyphosate. EAP-738-F-93-011, September 1993,
Environmental Protection Agency, Washington, DC.
http://www.epa.gov/oppsrrd1/REDs/old_reds/glyphosate.pdf
U.S. EPA (1997) Glyphosate; Pesticide Tolerances for Emergency Exemptions. Final Rule; Environmental
Protection Agency. Federal Register 62(154): 42921-42928.
Williams GM, Kroes R, Munro IC (2000) Safety evaluation and risk assessment of the herbicide Roundup and
its active ingredient, glyphosate, for humans. Reg Toxicol Pharmacol 31(2):117-165.
http://www.idealibrary.com/links/doi/10.1006/rtph.1999.1371
WHO (1994) Environmental Health Criteria 159: Glyphosate. World Health Organization. Geneva, Switzerland.
http://www.inchem.org/documents/ehc/ehc/ehc159.htm
Backgrounder: Glyphosate and Reproductive Toxicology. 2002. Page 2 of 2
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