The Centers for Disease Control recently reported on cases of illness it has been tracking, not caused by some new super-bug, but rather from a common-enough household product called “pest strips.” ( These are dichlorvos (DDVP) pesticide-laced (the CDC prefers to say “impregnated”) objects that are intended to leach out vapors wherever they hang.      

And there’s the rub. Not that Hamlet contemplated suicide by pest strip. But bedbugs, which have been a marketing boon for pest strips, are so much on the popular mind that even the Folger Library has been trying to make a Shakespeare connection (

The State of Washington has taken a real lead on pest strip mishaps. Indeed, many of the cases tallied by the CDC seem to come out of Washington State – not because people there are especially enamored of DDVP but because they actively look for reports of problems ( One mini-outbreak occurred when a family used pest strips to for bedbug control by attempting to reproduce an experiment they had read bout online study. They heated the strips in the bedrooms they wanted to treat and even though they didn’t sleep in the rooms during the process, and ventilated the space in follow-up, the family reported breathing and stomach symptoms for weeks afterwards, whenever they were home. The Washington State Health Department concluded that there was a double whammy of fast release of toxic vapor through heating and then likely recirculation through the home’s heating ducts.

It seems that a common theme in many exposures scenarios leading to symptoms results from “misunderstanding of label instructions” as the CDC says. They point out that the strips come in widely different sizes and that label directions differ across sizes and across brands of the same size. The labels specify using in a space up to 900–1,200 cubic feet (that’s easy for the average consumer!) and, moreover, according to the CDC not all labels warn again use in a smaller space. Despite the fact that all labels are supposed to make clear that the strips are not to be used in a space occupied by humans more than 4 hours per day, some labels say it’s ok to use a pest strip in an office space. Washington State expands on this labeling theme, “Some people are confused by the directions on the product label. The label states that the product can be used in garages, attics, and sheds as long as they are not occupied by people for more than 4 hours per day. The strips should not be used in general living or sleeping areas. The label also says the pest strips can be used in vacation homes, cabins, and mobile homes - but only if “unoccupied for more than four months immediately following placement of pest strip."

Furiously soft-peddling, the CDC concludes that, “Preventing DDVP pest strip–related illnesses requires educating the public regarding how to correctly use DDVP pest strips and how to control insect pests using methods with the least possible health and environmental hazards.” Unless part of that education campaign is sending everyone who intends to use the strips for graduate training in toxicology first, it might more sense to have stricter controls.

The Federal EPA has not exactly been leading the charge on this, either. Its web page “Protecting Children Where They Live,” about potential pesticide exposure in the home, puts forward a number of generalities but doesn’t have one word about pest strips ( A useful webpage from Washington State University’s pesticide program, “Learning About Labels,” sets forth three pillars of protection ( 1.Pesticides must be registered by the U.S. Environmental Protection Agency before they can be sold or applied (it’s been a long time since the EPA revisited DDVP); 2. Pesticide labels provide necessary information to pesticide users for safe handling (you shouldn’t have to be a forensics expert tp understand); 3. Pesticides must be used according to label instructions to achieve effective pest control and safe handling (by hanging one in your office?). It seems that for pest strips these three pillars are bit wobbly.

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