Three juries have determined that glyphosate, the active ingredient in the herbicide Roundup, is a carcinogen. These verdicts are in agreement with the International Agency for Research on Cancer, which concluded that glyphosate is likely to cause cancer, and other scientific studies that have linked glyphosate to the disease. However, recently published research focusing on Roundup's “inert” ingredients suggests that there may be more to it than glyphosate.
Scientists who have been working at the National Toxicology Program for the past few years have found evidence to suggest that the problem may not be glyphosate by itself, but rather, the way it interacts with the inert ingredients in glyphosate-based formulations (GBFs).
Roundup and similar products based on glyphosate also contain other herbicides as well as substances known as surfactants. A surfactant is something that makes a liquid “wetter” and more easily absorbed and/or spread on surfaces to which it is applied. A common surfactant is ordinary soap. Others include lecithin, used as a supplement and as an ingredient in some prescription medications, and “quaternary ammonium,” which can be found in disinfectants.
One surfactant known to have been included in Monsanto's Roundup is POEA, a substance known to be toxic to fish and other water-dwellers. The use of POEA in agriculture was banned in the European Union four years ago.
Unfortunately, inert ingredients such as these are considered to be “trade secrets,” so manufacturers of GBFs are not required to disclose them.
In addition to surfactants, GBFs can also contain herbicides such as diquat dibromide, which is used to speed up the drying process of crops prior to harvesting (Roundup is frequently used for this purpose). Mesotrione, sold the brand names Callisto and Tenacity, is another herbicide contained in GBFs, and disables a plant's ability to produce carotenoid, a substance necessary to protect chlorophyll from degradation by sunlight. Yet another herbicide found in GBFs is metolachlor, which acts by preventing the synthesis of plant proteins.
While researchers at the NTP were unable to determine whether DNA damage is caused by the surfactants or the added herbicides, they did conclude that “...while glyphosate alone lacks genotoxic activity, the genotoxicity [DNA damaging effects] of GBFs may require further evaluation.” It is known that DNA damage and mutation can lead to the formation of certain cancers.
One question that has been raised in glyphosate litigation is how much the original manufacturer, Monsanto, knew about its flagship product's toxicity. In one internal company email, a Monsanto employee wrote: “You cannot say that Roundup is not a carcinogen...we have not done the necessary testing on the formulation to make that statement. The testing on the formulations are not anywhere near the level of the active ingredient.” As late as 2010, Monsanto executives admitted that they had no reliable way of testing Roundup for cancer-causing properties. However, in 2002, someone at the company admitted that Roundup's formulation was potentially harmful – even if glyphosate alone was not.