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Question

Are there detectable levels of the chemicals used on GMO crops present in the harvested portion of those crops?

Submitted by: briangeer


Answer

Expert response from Dr. Daland R. Juberg

Toxicologist and North American Leader of the Human Health Assessment Group, Dow AgroSciences

Monday, 03/02/2014 20:26

In some cases, crops have been genetically modified to metabolize a herbicide so that the crop, which would otherwise be injured by the herbicide, is now tolerant, thereby providing new weed-management technology to aid in efficient crop production. In these instances, residue levels of the herbicide in crop commodities at the time of harvest are likely to be nondetectable, or, if detected, are likely to be present at only trace levels. It is possible that while the parent herbicide may not be detected, a metabolite that is formed as the herbicide is metabolized by the plant may be detectable at the time of crop harvest.

 

In other situations, the trait conferred to a GM crop may make it unnecessary to treat the crop with a chemical for control of a particular pest. For example, a GM crop having a trait that confers insect resistance may not need to be treated with an insecticide for a particular insect pest, and in that instance the GM crop would have no insecticide residues, while a crop lacking that trait may have required application of an insecticide to avoid damage from insects and might have detectable residue at harvest, depending on the properties and use pattern of the insecticide. 

 

Aside from these two situations, levels of chemical residue in crops at harvest are unlikely to be affected by whether or not the crop is a GM crop, since the genetic modification made to the crop does not have an effect on the levels of chemical residue, and instead, the factors determining the levels of residue, if any, detectable at harvest would include properties of the chemical, the way the chemical is used (use pattern/labeled use) and weather/environmental conditions. However, in all cases, the residues of a chemical or its metabolites, if any, remaining in crop commodities harvested for use as food or feed are evaluated through a rigorous regulatory process to provide reasonable certainty of no harm to humans or the environment from use of crop protection chemicals, when used as labeled. Monitoring data are publically available on the website of the USDA PDP program that demonstrate the low levels of pesticide residues present on U.S. foods.