Pyrethroid label changes hit the streets soon

You can recognize a pyrethroid insecticide by
reading the active ingredient list.  Pyrethroid
common names end with  the suffixes "-thrin"
(such as bifenthrin) or -ate (such as esfenvalerate).

The past few years has seen a major shift in the insecticides the pest control industry uses to provide long-term, residual control of general insect pests.  In the 1990s and early 2000s, chlorpyrifos, diazinon and assorted other organophosphate (OP) and carbamate insecticides dominated much of the pest management professional and consumer pesticide markets. Passage of the 1996 Food Quality Protection Act, and a conscious effort by U.S. EPA regulators to wean the country from OPs, created a regulatory environment that favored pesticides with lower toxicity potential for human and wildlife. Indeed, a recent study by Alison Clune and colleagues from Emory University provides experimental evidence that levels of OP metabolites in human urine decreased significantly between 1999 and 2004.

This decline in OP and carbamate use in pest control opened the door for increased use of pyrethroid insecticides. For the most part, pyrethroids have proven to be good substitutes for the older insecticides; however in recent years there have been growing concerns that pyrethroids might not be as environmentally safe as originally thought. Specifically, pyrethroid residues are increasingly being found in sediment at the bottom of urban streams and rivers, where they are toxic to some aquatic insects and other invertebrates.

What this means for the average pest control technician is that there will be changes over the next few months in wording on all pyrethroid labels to minimize the risk of stormwater contamination from structural pest control.  PestWeb just published a nice summary of the new rules and timelines for implementation, and the Pyrethroid Working Group (a pesticide industry coalition) also summarized the upcoming changes and offers the opportunity to sign up for email alerts on changes to regulatory alerts on pyrethroid insecticides.

It's always important to read pesticide labels, but this change means that all PMPs should be especially alert to changes in the labels of these commonly used products.  The biggest changes will be in how pyrethroids are applied to outdoor impervious surfaces. All applications made to sidewalks, driveways, patios, porches and structural surfaces (such as windows, doors, and eaves) will be limited to spot and crack-and-crevice applications only (around windows and doorways this is defined as a spray band no more than a one-inch wide). In addition, if you are in the habit of using pyrethroid insecticides to treat sewer lids or walls for cockroaches, this type of application will be specifically prohibited.