Glyphosate (Weedkiller) Safety Concerns

Glyphosate and it’s controversial benefits and dangers seem to be surfacing in politics around the world. Glyphosate is a synthetic herbicide used to kill broadleaf plants and grasses. You may know this chemical from the common weedkiller, Round-Up. Glyphosate is sold in liquid and solid products. This herbicide is advertised as having a low toxicity to humans and animals and it has been readily available to the public since the 1970’s. 

However, some organizations believe that Glyphosate is a carcinogen, meaning the potential to cause cancer. There is also the claim that it ultimately degrades the environment and harms our economy.

In the past 5 years alone, multiple countries have banned the herbicide altogether such as the Czech Republic, Denmark, India, Belgium, Bermuda, Sri Lanka, El Salvador, and most middle eastern countries. Countries such as Canada and the European Union have made progress to limit the use of Glyphosate.

However many agencies and organizations have carried out studies that show evidence that Glyphosate is not a carcinogen and is actually beneficial for the economy.

In addition to the claim that Glyphosate is a carcinogen, it is also believed that it is an endocrine disruptor and that it bioaccumulates in breast milk. Studies have shown that Glyphosate does not pose a threat to human health. The claims against Glyphosate being a carcinogen are completely unjustified. Many studies testing if Glyphosate is a carcinogen actually used rodent carcinogen bioassays.

Even then, there was a lack of association between tumor growth and Glyphosate which resulted in an “expert panel (concluding) that Glyphosate is not carcinogen in laboratory animals” (Williams, 2016). These tests have been done by various agencies/organizations, some of which include the U.S. EPA, The World Health Organization (WHO), and Pest Management Regulatory Agency (PMRA) (Canada).

The International Agency of Research on Cancer (IARC) monograph for Glyphosate attempted to prove the harmful effects but many of the references that were cited were old and indefinite. They stated that Glyphosate is “probably carcinogenic to humans.”  In the monograph, the IARC even admit that they have “limited evidence” that Glyphosate has carcinogenic effects.  Another important thing to remember is that the IARC claims were not confirmed by either by the EU assessment or WHO/FAO evaluation agencies.

Another agency is the Endocrine Disruptor Screening Program (EDSP). The program was developed to study substances and the effects of those substances on the human endocrine system. Substances go through a two-tier assay process.

Tier 1 assays are designed to see if the substance, in this case Glyphosate, has the potential to interact with estrogen, androgen, or thyroid pathways.

Tier 2 carries out further long-term studies that establish the dose response of the xenobiotic.

Uterotropic assays and Hershberger assays were performed on mice to assess the effects of Glyphosate on estrogen, androgen, and thyroid pathways. Glyphosate was subjected to the two-tier assay testing. After the extensive process, “the conclusion of the Weight of Evidence (WoE) evaluation is that Glyphosate exhibits no convincing evidence of potential interactions with estrogen, androgen, or thyroid pathways in mammals or wildlife” (EPA, 2015).

The allegations that high concentrations of Glyphosate were found in the breast of nursing mothers is completely false. The Moms Across America (MAA) published a non-peer reviewed study about how Roundup weed killer and Glyphosate cause serious health and environmental hazards. The MAA claims that Glyphosate is able to bioaccumulate in humans but this is not true because Glyphosate is water soluble and not a fat soluble. Since it is a water soluble, Glyphosate is excreted through urine. The data collected by the MAA is inconclusive because they used an antibody-based assay that was originally used to qualitatively analyze water (Bus, 2015). This method does not translate to breast milk, therefore the data should not have even been published for the public to read.

The use of Glyphosate does not pose a threat to the environment. In fact, it is commonly used for habitat restoration and safely degrades in the soil. The use of Glyphosate as a weed killer allows farmers to reduce the amount of times they have to tillage their land. This, in turn, reduces emissions produced by agriculture equipment such as tractors. It is also beneficial to the farmer as it reduces the amount of labor and limits soil erosion (Givens, 2009). By growing Glyphosate resistant crops, such as corn and sugar beets, farmers reduce the number tillage from five passes to just one pass.

The Saguaro National Park is an example of how Glyphosate can successfully be used for habitat restoration. The Saguaro National Park in Arizona applied Glyphosate to 527 acres in hopes of eradicating an invasive grass species called Buffelgrass. The National Park Service created a Restoration Plan and Environmental Assessment (RPEA) that described why they decided to treat the land with Glyphosate.

Glyphosate was chosen because it affects the enzyme pathways in plants that do not allow the plant to grow while non-targeted biological resources are impacted minimally (SNP, 2015). The goal in applying Glyphosate was to eradicate invasive weeds which were competing with native vegetation. The National Park Service would not add the herbicide to such a vast portion of land if they thought that there would be negative adverse effects. The microbes in the soil are able to degrade Glyphosate. The rate of degradation depends on the makeup of the soil. Degradation of Glyphosate is possible in both aerobic and anaerobic conditions. Studies have shown that Glyphosate has no significant effect on the bacteria and fungi found in forest soil (Stratton, 1992). The nitrogen fixing ability of the soil is not affected by the application of Glyphosate.

Glyphosate benefits the economy by simplifying agricultural practices, reducing labor time, and increasing crop yields. Glyphosate is one of the most effective herbicides that is currently on the market. The use of this herbicide reduces the time for tillage and hand labor which subsequently makes agriculture more efficient for farmers. The practice of tillage was time consuming before Glyphosate was introduced. The use of Glyphosate reduced tillage practices. Before Glyphosate farmers had to plow the field at least 5 times to get rid of weeds but with the introduction of Glyphosate farmers only have to plow once to embed the seeds into the soil. Costs and labor for weed management were reduced with the introduction of Glyphosate.

In developing countries, the use of Glyphosate reduces the labor done by women and children (Haggblade, 2017). This allows these demographics to participate in other economic opportunities and attending school. The reduction of cost and labor result in positive economic growth (Johnson, 2000). With more efficient weed management techniques comes higher yields since crops do not have to compete with invasive weeds for nutrients.

The space taken up by weeds can be used for crops instead when the weeds are eradicated from the fields.  Without weeds, crop yields are greater and the quality of the crop is better. Overall, the use of Glyphosate produces a better product. Higher produce yield allows prices for good quality produce to decrease at the supermarkets. Glyphosate saves farmers’ money, time, and resources.

In conclusion, Glyphosate is a safe and effective herbicide. The use of Glyphosate should be continued in agricultural, industrial, and domestic settings. The negative allegations against Glyphosate are unmerited. Many credible agencies and organizations have proven with data that Glyphosate does not pose any health hazards to humans and does not degrade the environment.

Not only does the U.S. economy benefit from the use of Glyphosate but so do developing countries. Focusing on conspiracies and scares from uneducated people limits the country and it is ultimately a  waste of time. Right now, the U.S. already has their own economic problems to deal with. I suggest we leave cancer scares and anti-vaxx propositions to the Moms of America and deal with some of the real problems at hand.

Bibliography

• US Environmental Protection Agency Endocrine Disrupter Screening Program: weight of evidence analysis of potential interaction with the estrogen, androgen or thyroid pathways. Chemical: glyphosate. Office of Pesticide Programs; 2015. D398693. EPA-HQ-OPP-2009-0361-0047.
• Bus, J.S. Analysis of Moms Across America report suggesting bioaccumulation of glyphosate in U.S. mother’s breast milk: Implausibility based on inconsistency with available body of glyphosate animal toxicokinetic, human biomonitoring, and physico-chemical data. Regul Toxicol Pharmacol. 2015 Dec;73(3):758-64. doi: 10.1016/j.yrtph.2015.10.022
• Gary M. Williams, Colin Berry, Michele Burns, Joao Lauro Viana de Camargo & Helmut Greim (2016) Glyphosate rodent carcinogenicity bioassay expert panel review, Critical Reviews in Toxicology, 46:sup1, 44-55, DOI: 10.1080/10408444.2016.1214679
• Haggblade, S., Minten, B., Pray, C. et al. Eur J Dev Res (2017) 29: 533. DOI: https://doi.org/10.1057/s41287-017-0090-7
• Johnson, W., Pauley R. Bradley, Stephen E. Hart, Michelle L. Buesinger, & Massey, R. (2000). Efficacy and Economics of Weed Management in Glyphosate-Resistant Corn (Zea mays). Weed Technology, 14(1), 57-65. Retrieved from http://www.jstor.org/stable/3988506
• SNP. 2015. Restoration management plan environmental assessment. Saguaro National Park. https://www.nps.gov/sagu/learn/management/restoration-plan.htm
• Stratton, G. W. and Stewart, K. E. (1992), Glyphosate effects on microbial biomass in a coniferous forest soil. Environ. Toxicol. Water Qual., 7: 223-236. doi:10.1002/tox.2530070303
• Wade A. Givens, David R. Shaw, Greg R. Kruger, William G. Johnson, Stephen C. Weller, Bryan G. Young, Robert G. Wilson, Michael D. K. Owen, and David Jordan “Survey of Tillage Trends Following The Adoption of Glyphosate-Resistant Crops,” Weed Technology 23(1), (1 January 2009). https://doi.org/10.1614/WT-08-038.1