HOW GLYPHOSATE AND ROUNDUP® AFFECT THE GROWTH OF C. ELEGANS

The US Environmental Protection Agency’s eligibility documents for glyphosate-based herbicides (GBH) state that they “can be used without posing unreasonable risk to people or the environment” (EPA-738-F-93-011). In contrast, the World Health Organization in 2015 classified glyphosate as a “probable carcinogen.” The EPA safety assessment of GBH is based on the testing of glyphosate salts (typically monoammonium or sodium salts) and not additional “inert ingredients” that are added in commercial preparations like Roundup® and which are critical for the effectiveness of GBH in use. The present investigation tested glyphosate and Roundup® separately to explore whether the unregulated ingredients in Roundup® pose a health risk. Our test model was the nematode C. elegans that is often used in toxicological research. Two separate dose-response experiments were conducted to test how glyphosate and Roundup® affect the C. elegans. The first experiment was a dose response that tested how exposure to 0%, 5% and 10% concentrations of pure glyphosate, for 1 hour, affected the survival rate of the nematodes. After 1 hour of exposure, the worms were moved to fresh petri plates, and the live worms were observed and counted daily, over the course of one week, with an inverted Zeiss microscope. We found that the 0% concentration control group had the greatest live-worm count, with 251 live worms, while the 5% and 10% experimental groups had counts of 21 and 5 live worms, respectively. The second dose-response experiment tested how exposure to different concentrations of Roundup® Concentrate Plus affected the survival of the worms. Starting with similar initial worm populations per test group, we tested concentrations of 0%, 25%, 50%, 75% and 100%. After one hour of exposure, the worms were transferred to fresh petri plates and the live worms were observed and counted daily for 7 days. At the end of 7 days, we found that the control group had the highest live-worm count, with 1063 live worms, and the 25%, 50%, 75% and 100% groups had counts of 310, 109, 131, 41 live worms, respectively. These data suggest that the active ingredient glyphosate, and the widely used glyphosate-based herbicide Roundup®, may be more harmful than currently recognized and deserves further study.