Farm workers and chemical workers suffer from the highest levels of exposure to pesticides, usually from inadequate protection and misuse of chemicals. Often, the workers are not educated about how to protect themselves or aren’t provided with adequate protective gear. Also, labor laws and protections for workers vary from country to country, and illiteracy and other linguistic problems can perpetuate the powerless state so many workers are in (Chiras, 496).
There are at least 45,000 annual cases of severe pesticide poisoning in the United States and 500,000 worldwide – probably low estimates. Annual U.S. deaths from pesticide poisoning are estimated to be between 200 and 1,000, and worldwide deaths are estimated to be between 4,000 and 19,000. The misuse of pesticides can affect consumers, as when hundreds of people on the West Coast were made sick by improperly treated watermelon in 1985 (Chiras, 497).
Monsanto’s weed-killer, Roundup (glyphosate), is often touted as a safer herbicide. It interferes with an enzyme in the chloroplast, resulting in plant death. Because their cellular structure does not contain the target site upon which glyphosate acts, Roundup doesn’t pose a health risk to mammals (assuming we’re talking about normal exposure and not the case of someone drinking a big cup of Roundup); furthermore, since it breaks down quickly it doesn’t build up in the soil or groundwater. Because soil does not need to be tilled as much when planted with Roundup-ready crops, its use can decrease soil erosion. Furthermore, since tilling leads to the death of ground-dwelling animals, methods that reduce the need for tilling can be considered animal-friendly. However, while glyphosate itself does not harm fish or amphibians, Roundup is mixed with a surfactant that is harmful to freshwater species (Cerdeira; Ronald, 69-70). Some proponents of Roundup say that the surfactant should be banned for this reason.
Roundup does not seem to have harmful effects on soil microbiota (as indicated by an experiment conducted in Northern Californian ponderosa pine plantations), despite previous experiments showing that glyphosate was toxic to bacteria in lab settings rather than in the soil itself. This is probably because in natural environments, glyphosate tends to bind to inorganic molecules and compounds (Busse).
This doesn’t mean that Roundup is a panacea. First of all, several species of invasive plants (i.e., weeds) have already evolved resistance to glyphosate (which poses more of a problem to farmers than it does to home gardeners). If such selective pressure continues, we might be back to square one and in need of developing new weed-control strategies, either through genetic engineering or other methods. Secondly, it is possible for Roundup to drift to non-target plants, killing them. Thirdly, there are many concerns over possible negative effects of transgenes from Roundup-ready crops transferring to other crops through pollen flow. While this is not much of a problem in nontransgenic soybean crops, outcrossing is quite prevalent among rice, corn, and canola crops. There is also the risk of a transgene finding its way into a wild plant population through backcrossing. Though this risk is deemed to be quite small, if it were to happen the effects might be irreversible, which could have negative ecological consequences (Cerdeira). The question might be, Is the small risk to wild plants posed by gene flow outweighed by the known risks associated with tilling and the use of harsher herbicides?
Busse, M.D., Ratcliff, A.W., Shestak, C.J., Powers, R.F. (2001). Glyphosate toxicity and the effects of long-term vegetation control on soil microbial communities. Soil Biology & Biochemistry, 33, 1777-1789. Obtained from http://www.fs.fed.us/psw/publications/busse/psw_2001_busse001_sbb.pdf
Cerdeira, A.L., Duke, S.O. (2006). The Current Status and Environmental Impacts of Glyphosate-Resistant Crops: A Review. Journal of Environmental Quality, 35, 1633-1658. Obtained from http://ddr.nal.usda.gov/dspace/bitstream/10113/7373/1/IND43835166.pdf
Chiras, D.D. (2010). Environmental Science. Jones & Bartlett Learning. Obtained from http://books.google.com/books?id=L28bHnPXo1AC&pg=PA496
Ronald, P.G., Adamchak, R.W. (2008). Tomorrow’s Table: Organic Farming, Genetics, and the Future of Food. Oxford University Press.