Most of us have picked up a bottle of Roundup from a home center and used it to kill weeds in our driveways and gardens. Roundup brand herbicides have a long history of safe use at home and in agricultural settings. As with most chemical products, appropriate precautions must be taken during handling and use of these products and the directions for use must be followed carefully. Almost all non-food products, including herbicides, would not be safe for human consumption straight out of the container, because most chemical products contain ingredients at levels significantly higher than would be acceptable for daily human consumption.
Drinking dishwashing detergent or shampoo out of the container, for example, is not advised, because these chemical products contain surfactants that should not be intentionally consumed, yet low levels of dishwashing detergent and shampoo residues are consumed daily off of cups, plates, and utensils and during showering, without adverse health effects. And rightfully so, people are not concerned about use, or consumption of trace amounts of detergents.
The same is true for herbicides. Roundup brand products also contain surfactants like those found in dishwashing detergents and shampoos and like these consumer products should not be intentionally consumed. However, low levels of these surfactants and the active ingredient in Roundup brand products (glyphosate) that gives it its weed killing power ingested from the food we eat are well below what has been determined as acceptable for daily human consumption.
The use of every herbicide on food crops in the U.S. is considered and evaluated by the Environmental Protection Agency (EPA) against a standard of reasonable certainty that the use would cause no harm to human health or the environment. In order to make this safety determination for Roundup products, EPA considers how much glyphosate residue the use would contribute to the daily intake and then adds that amount to the amount of glyphosate residue consumed by all other possible routes of exposure including on other foods, in drinking water, through accidental ingestion of water during swimming, etc. This total consumption of glyphosate residues are then compared to the total Acceptable Daily Intake, or ADI, that has been established for glyphosate, based on toxicity studies that look at a variety of toxic effects, such as immediate or acute toxicity, effects on reproductive processes, cancer-causing and other long-term effects, etc. Just to be on the safe side, the EPA sets the Acceptable Daily Intake (ADI) a minimum of 100-times lower than any dose level that showed any kind of toxicity in any study conducted. No more uses of a pesticide like Roundup brand products can be added once the ADI has been reached. If use of a pesticide is expanded, the additional consumption has to be considered.
The ADI of glyphosate, and many other herbicide active ingredients, has been established by the U.S. EPA and independently by regulatory authorities in different parts of the world, including the World Health Organization. Whether taken in as food or drink, these ADI levels are conservatively calculated based on animal models, crop residues and typical diets to account for daily exposures throughout our lives. Daily consumption of residues below the ADI is considered safe.
A recent risk assessment was conducted by EPA for glyphosate exposures through both food (agricultural products) and water and they concluded glyphosate exposure is no more than 13% of the ADI. This risk assessment takes the conservative approach that all fruits, vegetables and grains in the diet treated with glyphosate had the maximum allowable residue levels remaining on those food crops when eaten, which is a very conservative assumption for glyphosate residue levels in food.
I realize that this has been a very technical answer for what was a simple question, but it emphasizes the scrutiny that is required to ensure your family and mine have safe food to eat.