TOXICITY OF GLYPHOSATE ON THE C. ELEGANS WORM: IMPLICATIONS FOR SOIL AND HUMAN HEALTH

Glyphosate is a broad spectrum herbicide that is mixed with additives to improve its effectiveness in the field. Approximately 650,000 tons of glyphosate based herbicides (GBH) were used globally in 2011. Glyphosate is commonly found in soil, consumer-based products, foods, human urine, and breast milk. Because of glyphosate’s widespread presence we investigated whether GBH are as safe as advertised by their manufacturers and as listed by the US EPA. The C. elegans worm was chosen as a test organism since it shares over 60% of its genes with humans, is often used for toxicological studies, and is commonly found in soils and rotting plant matter. We conducted two experiments, each with a different type of GBH: Super Concentrate Roundup® (S.C.) and Concentrate Plus Roundup® (C.P.). The S.C. is composed of 50.2% glyphosate and the C.P. is composed of 18% glyphosate. Both products contain unspecified surfactants in the “inert ingredients” listed on their labels. We chose GBH rather than pure glyphosate since the additives listed as inert ingredients have been implicated as harmful to humans and the environment. Worms were exposed in micro-titer wells for 80 minutes to concentrations of glyphosate ranging from 0.0% glyphosate to 1.0% glyphosate. The number of dead worms was recorded every 20 minutes over the course of the 80-minute experiment. In the S.C. GBH experiment, after 80 minutes of exposure, 96.8% of worms died in the 1% glyphosate solution, 58.5% of worms died in the 0.1% glyphosate solution, 31.3% of worms died in the 0.01% glyphosate solution, and 21.1% of worms died in the control (0.0% glyphosate solution). In the C.P. experiment, after 80 minutes of exposure, 98.1% of the worms died in the 1% glyphosate solution, 63.1% of worms died in the 0.1% glyphosate solution, 30.2% of worms died in the 0.01% glyphosate solution, and 21.9% of worms died in the control (0.0% glyphosate solutions). The deaths in the control groups may be attributed to variables in the exposure and observational procedures. At the recommended dilutions listed for S.C. and C.P., the resultant solution was 1% glyphosate. This was the highest concentration tested and resulted in the most death. These data suggest that Roundup® is deleterious to C. elegans at the concentrations used in this study and since nematodes make up part of a healthy soil environment it has implications for soil health.