Current Understanding of the Health Risks
Associated with Glyphosate Products

Prepared by John Hausbeck, Environmental Epidemiologist
Madison Department of Public Health

23 October 2002

Over the last five years, the total reported application of glyphosate-containing herbicides (Roundup, Razor, and Ranger) by City agencies has increased. This increase in application has resulted in questions concerning the environmental and human health impacts of these herbicides. The following is a brief summary of information that is available from various governmental agencies and the published literature on Roundup and other glyphosate-containing herbicides.

The US Environmental Protection Agency (EPA) first registered glyphosate in 1986. In 1993, the EPA issued the Reregistration Eligibility Document (RED) for glyphosate based on additional toxicity analysis and review. This report documented that glyphosate was in compliance with more stringent pesticide safety standards established after the product was first registered. Glyphosate is currently registered as a general use pesticide because of its low toxicity. A review of toxicity data for glyphosate and Roundup by the World Health Organization (WHO) also found these herbicides to have low toxicity. Neither the EPA nor the National Toxicology Program considers glyphosate to be a carcinogen. The International Agency for Research on Cancer (IARC) does not appear to have evaluated glyphosate for carcinogenicity.

Although glyphosate is considered to have low toxicity, there is some concern regarding glyphosate-containing product safety with respect to human health and the environment. The following are some of the arguments that are being made against glyphosate-containing herbicides:

• Inert ingredients. The term "inert ingredients" refers to chemicals in a pesticide that are not directly responsible for killing the target pest. These chemicals "help" the active ingredients (chemicals directly responsible for killing the pest) perform their intended task. In the case of Roundup, one or more of the inert ingredients are surfactants that allow glyphosate to penetrate plant tissues. The most commonly mentioned surfactant is polyoxyethyleneamine (POEA). Toxic effects of this and other surfactants are due to their ability erode tissues including mucous membranes and linings of the gastrointestinal and respiratory tracts. Common effects after accidental or intentional ingestion of Roundup include oral and throat pain; mucosal erosion or ulceration; and vomiting. Label precautions also warn of irritation if product comes in contact with the skin or eyes. Presumably, the surfactant would be the causative agent for these effects; however, there is insufficient data on exposures to Roundup to be certain.
  
• Carcinogenicity. Glyphosate is not currently considered to be carcinogenic. However, a recent epidemiological study by Hardell et.al. has reported that past use of Roundup is associated with an increased risk of non-Hodgkin’s Lymphoma (Leuk Lymphoma 2002; 43(5):1043-9). Further research is necessary to confirm this finding.
  
• Amount of use. Glyphosate is one of the most widely used pesticides in the United States and throughout the world. And many assume the amount of these products applied may increase due to the recent developments in genetically engineered crops that are resistant to glyphosate. As use increases, the potential for incidental exposure to this chemical in water and food is suspected to increase. Another concern is that overuse will eventually result in development of resistance in target weeds and a reduction in the usefulness of the herbicide.

Benefits to the use of Round-up and other glyphosate-containing herbicides include:

• Lower toxicity to humans and animals then other commonly used herbicides.
• Not considered to be a likely groundwater contaminant like atrazine and other triazine herbicides.

Based on this information and the requirements within the City Pesticide Use Policy, Roundup and other glyphosate herbicides continue to be an acceptable part of city integrated pest management plans. While there is some concern about the safety of these herbicides, the current City Pesticide Use Policy should address the issues of overuse and toxicity of surfactants. Overuse of pesticides is a global issue that everyone can address by minimizing the use of pesticides. According to the policy, city staff should continue to minimize the use of any chemical pesticide to the minimum amount necessary to achieve the desired result. Also, the policy requires that city employees that apply chemical pesticides are licensed pesticide applicators. This and identification of treated areas should minimize the potential for accidental exposure by employees and the general public to these herbicides.