This is part three of our six-part series on the current state of pesticides.
Information about pesticides is ubiquitous online. Unfortunately, a balanced and nuanced discussion about the benefits and drawbacks of current pesticides is difficult to find. This series discusses the main concerns surrounding pesticides and illuminate the complexity and challenges involved in decision-making regarding current and future pesticide use.
This series contains six parts:
  • In Part 1, we explore why looking solely at pesticide use by weight does not fully illustrate how pesticide use has changed over time. Incorporating other factors is needed to gain a fuller understanding of how pesticide use has changed.
  • Part 2 explores changes in pesticide toxicity and environmental impact over time. We look at the range of toxicity and environmental impact among different pesticides and highlight where there is room for improvement.
  • In Part 3, we compare the toxicity of a pesticide whose toxicity is often debated on social media and the press – glyphosate – to other common pesticides to give context to a polarized issue.
  • Part 4 compares toxicity between common synthetic and organic pesticides and highlights the complexity and variability in pesticide options.
  • In Part 5, we provide an example of how organic farming can sometimes include less sustainable environmental practices.
  • Part 6 addresses the common concern that conventional produce contains unsafe levels of pesticide residues and the common belief that organic produce is safer and healthier.

How dangerous is glyphosate?

Although pesticide toxicity and biodegradability has decreased overall, many consumers are still worried about pesticides. They are especially concerned with specific pesticides that are portrayed as dangerous by the media.

A bottle of the pesticide RoundUp

Foremost among those is glyphosate.

[GLP GMO FAQ: Is glyphosate (Roundup) dangerous?]

Glyphosate (the active ingredient in RoundUp) has drawn attention in the media in recent years, alleged by advocacy groups as being toxic and dangerous. But study after study has shown that it is one of the least toxic herbicides on the market and does not accumulate in the soil. How does glyphosate fit into the context of all current pesticides? How does glyphosate toxicity compare to other pesticides? And how does glyphosate toxicity compare to other common substances?


How dangerous is glyphosate?

Before understanding the toxicity of glyphosate in the context of other pesticides and substances, it is important to clarify what toxicity means. Toxicity, the degree to which a substance can damage an organism, can be measured and compared in various ways. Acute toxicity refers to the immediate effects of exposure to a certain dose of a substance. Chronic toxicity refers to the effects of being exposed to a certain dose of a substance multiple times over the course of a certain period, for example, once a day for months or years. Acute toxicity is what we think of when someone gets poisoned by a substance. Chronic toxicity is usually what most consumers are worried about concerning pesticides: what are the effects of being exposed to small doses of pesticides, on our produce, for example, over a long period of time?

For every substance, what matters is at what dose the substance becomes toxic for a specific organism, like an insect or a human. For both acute and chronic toxicity, substances are not “toxic” or “not toxic.” Even water is toxic if you ingest too much of it at one time. In addition, a substance can have high acute toxicity, and low chronic toxicity, or vice versa. Acute and chronic toxicity are not necessarily correlated. The point is, claims that glyphosate “is toxic” are not meaningful – only by comparing a pesticide’s acute or chronic toxicity with other well-known substances do we get a true understanding of the safety or danger of that pesticide.

Now, back to glyphosate. Glyphosate makes up 25% of all pesticides used in corn in the U.S.

Pesticides used on corn:

              25%     Glyphosate

75%     All other pesticides

However, it only accounts for 0.01% of the chronic toxicity hazard of all pesticides used in corn.

Chronic toxicity hazard from pesticides used on corn:

0.01%     Glyphosate

99.99%     All other pesticides

This suggests that glyphosate is much less toxic than other common pesticides.

It is helpful when analyzing toxicity to compare pesticide toxicity with other common substances. For example, caffeine is over ten times more acutely toxic than glyphosate. To die from poisoning, a 140-pound human would have to:

Comparison of how much coffee and how much glyphosate would cause an overdose in a human.

Compared to other pesticides and even things we find in common food and drink, like caffeine or vitamin D, glyphosate is low in toxicity. However, many are still suspicious and fearful of the possible consequences of regular glyphosate use. The use of pesticides is always about trade-offs. We need pesticides to produce enough crops to feed the world. Protecting and increasing crop yields through the use of safe pesticides is more sustainable and environmentally-friendly than letting land and resources go to waste because of unsubstantiated fears concerning chemicals.

Of course, the safety and health of humans, animals, and the environment are critically important. The use of specific pesticides always needs to be weighed against the alternative: which alternative pesticides will be used if one is banned? Are certain pesticides allowing for more sustainable farming practices that will be halted if other pesticides are used?

In the case of glyphosate, possible glyphosate bans in European countries may lead to less sustainable farming practices along with the possible use of more toxic pesticides. Specifically, glyphosate is an effective way to prepare fields for seeding by getting rid of weeds and plant cover. By using glyphosate, farmers had been able to stop tilling. Tilling the soil is a farming practice that also helps prepare fields for planting, but it increases erosion, reduces biodiversity of insects and animals in the soil and releases greenhouse gas into the atmosphere (see Part 5 of this series for more information on tillage). Therefore, banning glyphosate can actually lead to the use of less sustainable farming practices. The balancing of pros and cons in pesticides and their interaction with farming practices is required regardless of whether pesticides are organic or synthetic. In the next post of this series, I will compare toxicity between common synthetic and organic pesticides, highlighting the complexity and variability in pesticides within both types of farming.

Kayleen Schreiber is the GLP’s infographics and data visualization specialist. She researched and authored this series as well as creating the figures, graphs, and illustrations. Follow her at her website, on Twitter @ksphd or on Instagram @ksphd.

Marc Brazeau is the GLP’s senior contributing writer focusing on agricultural biotechnology. He also is the editor of Food and Farm Discussion Lab. Marc served as project editor and assistant researcher on this series. Follow him on Twitter @eatcookwrite.

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