Glyphosate (N-phosphonomethylglycine), the active ingredient in the herbicide Roundup that is manufactured by Monsanto (though the formulation is no longer under patent) is according to the authors, the most popular herbicide in use today in the United States, and increasingly throughout the World. Today, Americans spray an estimated 180-185 million pounds of the weed killer, on their yards and farms every year. All the acute toxicity tests have indicated glyphosate is nearly nontoxic to mammals. The typical description (by services that want to spray it in my yard) is that you could drink a bucket of the stuff and be perfectly fine. Thus, any residues of glyphosate that are ingested from food sources are safe. As a consequence, measurement of its presence in food is practically nonexistent. Glyphosate and its metabolite aminomethylpholphonic acid (AMPA) have not been covered in the reports from the Center for Disease Control on Human Exposure to Environmental Chemicals, so human exposure has not been measured.
Nonetheless, there have been for some time a minority of scientists and experts who believes that glyphosate may instead be much more toxic than is claimed and Anthony Samsel and Stephanie Seneff have put together their paper to argue the case for reexamining potential impacts to human health from low level constant exposure to glyphosate and studying that exposure. In humans, only small amounts (~2%) of ingested glyphosate are metabolized to AMPA, and the rest enters the blood stream and is eliminated through the urine. The philosophy that tiny amounts of chemicals are of no health consequence has been the cornerstone of toxicology and regulation, but that has recently come into question with our increased ability to measure trace amounts of chemicals. For many environmental chemicals, more research is needed to determine whether exposure at the extremely low levels is a cause for health concern.
While correlation does not necessary imply causation, the authors develop the argument that the recent increase in digestive issues, obesity, autism, Alzheimer’s disease, depression, Parkinson’s disease, liver diseases, and cancer can be traced back to a combination of gut dysbiosis, impaired sulfate transport, and suppression of the activity of the various members of the cytochrome P450 (CYP) family of enzymes. In the literature study they found evidence that glyphosate disrupts gut bacteria and suppresses the CYP enzyme class.
As the authors point out the Western diet is a delivery system for glyphosate and other potentially toxic chemicals used in industrial agriculture. The diet they refer to consists primarily of processed foods based on corn, wheat, soy and sugar, consumed in high quantities. Chemical residues of insecticides, fungicides and herbicides like glyphosate contaminate the diet. In addition, since 2000 there has been widespread adoption in the U.S. of Roundup Ready® (RR) crops, for the production of soy, beet sugar, and corn. Confined animal feeding operations (CAFOs) are used to produce corn feed animals that produce meat that is vastly different from pasture raised, grass feed cows, pigs, sheep, goats, chickens. Now we are even feeding farm-raised fish corn. According to the authors the corn feed to these animals is laced with herbicide due to the late application of the herbicide. As a consequence, animal products like, eggs, butter, cheese and milk are also contaminated with these residues. The authors argue that glyphosate enhances the damaging effects of other food borne chemical residues and environmental toxins as well.
This paper is certainly food for thought, but without measurements of the presence of AMPA in human populations and further research there is only speculation. The authors do propose a pathway of impact to human health that should be investigated further. This paper was prepared (and peer reviewed) to be submitted to the U.S. EPA for consideration in the standard registration review they are conducting of glyphosate to determine if it’s use should be limited. The study is among many comments submitted to the EPA that is expected to complete their review by 2015. Monsanto and industry experts have submitted a review of their studies and believe that glyphosate has been proved safe to humans and the environment. As for me, I feel good about the “extra” money I spend buying organic grass fed meat and organic foods and all that extra time I spend cooking and preparing food. My personal decisions on pesticides and herbicides is a blanket policy because my well draws from a shallow aquifer in a fractured rock system.
|The proposed route of human impact of glyphosate from the article.|
Samsel, A.; Seneff, S. Glyphosate’s Suppression of Cytochrome P450 Enzymes and Amino Acid Biosynthesis by the Gut Microbiome: Pathways to Modern Diseases. Entropy 2013, 15, 1416-1463