On March 25, 2016, the U.S. Environmental Protection Agency’s (EPA) Office of Inspector General (OIG) sent a memorandum to Jim Jones, Assistant Administrator, Office of Chemical Safety and Pollution Prevention (OCSPP), announcing that it plans to begin preliminary research to assess EPA’s management and oversight of resistance issues related to herbicide tolerant genetically engineered (GE) crops.  OIG states that its review will include the Office of Pesticide Programs (OPP), as well as other applicable headquarters and regional offices.  OIG’s objectives are to determine:

1. What processes and practices, including alternatives, EPA has provided to delay herbicide resistance;

2. What steps EPA has taken to determine and validate the accurate risk to human health and the environment for approved pesticides to be used to combat herbicide resistant weeds; and

3. Whether EPA independently collects and assesses data on, and mitigates actual occurrences of, herbicide resistance in the field.

OIG states that the anticipated benefit of the project “is a greater understanding of herbicide resistance[,] which will lead to an enhancement of EPA’s herbicide resistance management and oversight.”

Commentary

Pesticide resistance is not a new issue and is one that EPA has affirmatively addressed when granting registrations for new products, GE or not, for some time.  In fact, that newer chemistries often have a more niche mode of action to reduce potential toxicity concerns has led some observers to speculate that greater resistance is one potential trade-off for the development of less toxic materials.

This “investigation” may appear to some to be a response to concerns raised by critics of GE crops generally and to a recent EPA decision to approve Enlist Duo herbicide, a new formulation of 2,4,D- and glyphosate designed to address the problem of weed resistance to glyphosate-tolerant crops.  Glyphosate tolerant crops were first approved some years ago, and their use was so broadly and readily adopted that issues have arisen with regard to potential resistance to some weed species.  EPA is currently expected to approve another GE strain, Dicamba-tolerant crops, to control glyphosate tolerant weeds.

To critics of GE crops, using more herbicides to control problems caused by what they claim is overuse of another herbicide is evidence of a troubling “pesticide treadmill,” which they believe should not have been allowed to occur in the first place.  Rebutting this criticism, others assert that resistance is a problem for all pesticides, not only genetically modified ones, and that with sufficient controls, resistance can be delayed, if not avoided.  Registrants point out that it is very much in their self-interest to take steps to avoid resistance to their products -- once that occurs, the market viability of the product is significantly reduced.