NOTES FROM SFA Gardens
By David Creech, Ph.D.
Is There Life after Glyphosate and Bacon? I WAS IN THE LOCAL feed store, and a friend remarked that it wouldn’t be long before glyphosate would be off the shelf. At home as I watched the local news, an ad asked viewers if they had non-Hodgkin lymphoma and had been exposed to Roundup. Those who answered yes were asked to join a class action lawsuit. Then I was eating breakfast with mom, and she had seen the news, noticed the ads, and was worried about her son. Thus, I’m writing this column. For many years I prepared students for the real world of commercial horticulture. I spent a good amount of time on pesticide handling and safety. Students learned LD50 is the lethal dose in mg/kg to kill 50 percent of a batch of test animals. There were oral, dermal, and inhalation toxicity issues to cover. There’s a difference between acute and chronic toxicity. Most high exposures happen when filling the tank while working with the raw product. Wearing protective masks and gloves, spraying when the wind is low, and just being cautious around chemicals make common sense. Well, move forward 30 years, and the topics are much the same. Enter the Roundup controversy. Introduced in 1974, glyphosate is long off patent, and there are generics everywhere. It’s the most commonly used herbicide worldwide, with both residential and agricultural uses. As for acute oral toxicity, glyphosate comes in with an LD50 of 5,600 mg/kg. That means a 175-pound human would have to ingest about a pound to have a 50
TNLA Green September/October 2019
percent chance of living or dying. It’s less toxic than caffeine or table salt. Suicide by drinking glyphosate is a poor idea. Of course, it’s not acute toxicity that has gotten glyphosate into the news; it’s chronic toxicity. That is, the impact of low, modest, and high levels over a short, medium, and extended period. While numerous studies have failed to find statistically significant associations with glyphosate use and cancer, everything changed in 2015. A report by the International Agency for Research on Cancer of the World Health Organization classified glyphosate as “probably carcinogenic to humans,” noting “strong mechanistic evidence and positive associations for non-Hodgkin lymphoma (NHL) in some epidemiologic studies.” This conclusion is an outlier in a world of international agencies that have concluded the opposite. Still it opened the door for the lawsuits and settlements making the nightly news. The argument continues. In the article, “Glyphosate Use and Cancer Incidence in the Agricultural Health Study,” Gabriella Andreotti and her coauthors updated a previous evaluation of glyphosate with cancer incidence from registry linkages (Journal of the National Cancer Institute (2018) 110(5):djx233).
This long-term follow-up study tracked 54,251 chemical applicators, of which 83 percent used glyphosate. The results indicated glyphosate was not statistically significantly associated with cancer. They concluded there was no association between glyphosate and any solid tumors or lymphoid malignancies overall, including non-Hodgkin lymphoma and its subtypes. While not statistically significant, however, there was an increased risk of acute myeloid leukemia (AML) in the highest exposure quartile compared with the “never users” group, and the increased risk of AML in this subset requires confirmation. Still counter arguments emerged, and the judgments continue. Google “glyphosate and cancer” and you’ll find a bevy of class action lawsuits and jury verdicts awarding millions of dollars to victims. Those cases are making their way through the courts. Bayer bought Monsanto in 2016. Since last July, Bayer has seen its shares drop by about 40 percent. Shareholders are worried. How risky is glyphosate? Well, it depends who you ask. What ultimately happens to glyphosate in the marketplace will be determined in the next few years. What about bacon? In 2015, the World