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I've heard that glyphosate causes development abnormalities in frogs. What's the truth and do you have scientific references to support this?

Submitted by: William Pilacinski


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Expert response from GMOAnswers Admin_1

Tuesday, 14/01/2014 21:34

There are data that suggest this, but the simple fact is that these studies utilized conditions that are not relevant to real-world exposures.  These studies were conducted either using exposure routes (e.g. injection or cell culture) not relevant for environmental exposure or using exposure concentrations or durations that greatly exceed worst-case environmental exposures, and environmental fate has not been included in the exposure regimen. Consequently, these types of studies must be interpreted with extreme caution. 

 

Exposure of tadpoles to glyphosate under environmentally-realistic conditions (concentrations and routes of exposure) has not resulted in developmental abnormalities.  For example, no adverse effects on tadpole growth or development were observed when tadpoles were continuously exposed for 21 days to glyphosate in water at the highest concentration required to be tested by the U.S. Environmental Protection Agency under test guideline OPPTS 890.1100 (U.S. EPA).[1]  Similarly, growth and development were not affected when tadpoles were chronically exposed to a glyphosate formulation in natural wetlands at environmentally relevant concentrations.[2]

 

It is also worth noting that some have alleged that effects on development, if true, would be due to endocrine activity.  However, glyphosate was recently screened in the EPA’s Tier 1 screening battery under the Endocrine Disruptor Screening Program [3] and based on the results of the validated EDSP Tier 1 assays glyphosate did not have endocrine activity.[4]  Additionally, Williams et al (2012)[5] performed a comprehensive review of the available literature to assess the developmental and reproductive safety of glyphosate and concluded “the literature shows no solid evidence linking glyphosate exposure to adverse developmental or reproductive effects at environmentally realistic exposure concentrations.”

The conclusions of the studies cited here and other relevant environmental studies with amphibians clearly show that when glyphosate is used following label directions it does not result in developmental abnormalities in frogs and other vertebrates.



[1] Schneider S., Krueger H., Claude J., Ross T., Gallagher S., Springer  T., and Jaber M. 2012. Glyphosate: Amphibian Metamorphosis Assay for the Detection of Thyroid Active Substances. Society of Environmental Toxicology and Chemistry, North America 33rd Annual Meeting, Abstract Book. Abstract No. 527, p. 127.

[2] Edge, C.B., Thompson, D.G., Hao, C. and Houlahan, J.E. 2012. A Silviculture Application of the Glyphosate-Based Herbicide VisionMax to Wetlands Has Limited Direct Effects on Amphibian Larvae. Environmental Toxicology and Chemistry 31 (10) 2375-2383.

[4] Levine SL, DA Saltmiras, EG Webb, C Holmes, SR Mortensen, JL Honegger, A. Tobia, J. Bailey. Tier 1 Endocrine Disruptor Screening Program (EDSP) Assays and Regulatory Safety Studies Provide a Weight of Evidence that Glyphosate is not an Endocrine Disruptor. Society of Environmental Toxicology and Chemistry, North America 33rd Annual Meeting, Abstract Book. Abstract No. 529, p. 128.

[5] Williams AL, Watson RE, DeSesso JM. 2012.Developmental and reproductive outcomes in humans and animals after glyphosate exposure: a critical analysis. J Toxicol Environ Health B Crit Rev. 2012;15(1):39-96.