Tuesday, January 21, 2014

Careful use of Nuvan strips

It may never be as big a seller as Vogue,
but the CDC's Morbidity and Mortality Report
covers some interesting news for PMPs.
The Morbidity and Mortality Weekly Report from the Centers for Disease Control will never make Amazon.com's Best Sellers in Magazines List.  In fact among all the subscriptions I receive, I'd be hard-pressed to think of one with a less appealing title. But sometimes this report has very useful information for entomologists and pest management specialists. This week's Notes from the Field feature looks at statistics concerning acute illnesses associated with Pest strips containing the insecticide dichlorvos (DDVP).

For anyone unfamiliar, dichlorvos is the active ingredient in (among other products) Nuvan™ Prostrips™, a slow release pesticide formulation for control of bed bugs, "flies, gnats, mosquitoes, moths, silverfish, cockroaches, spiders, beetles, earwigs and other pests".  Dichlorvos looked like it might have seen the last of its days a few years back, at least partly because of its acute toxicity. It is a holdover from the era of organophosphate insecticides, and like all OPs, it acts as an acetylcholinesterase inhibitor.  But dichlorvos has a unique property: its relatively high volatility makes it useful as a fumigant.  And thanks to its effectiveness against bed bugs, dichlorvos now appears to be staging a comeback.

Dichlorvos kills pyrethroid-resistant bed bugs. But it can also hurt people if not used carefully as described in the label. The CDC study reports on 31 acute DDVP pest strip–related illness cases recorded from seven U.S. states and Canada from 2000 to 2013 (more cases undoubtedly occurred that were not part of this study). Most of the illnesses resulted from using the product in commonly occupied living areas (e.g., kitchens and bedrooms), in violation of label directions. According to the report, "Although 26 of the 31 cases involved mild health effects of short duration, five persons had moderate health effects."  Illnesses included neurological, respiratory and gastrointestinal symptoms. Effects due to dichlorvos overexposure usually resolve themselves completely, according to the study; but make no mistake--this insecticide should be used with care.

The report concludes that in order to prevent dichlorvos-related illnesses, the public should be educated on correct use of pest strips, and how to control insect pests using safer pest control methods.  I would add that it's important for professionals to be reminded of the safe use of these products and the importance of reading the fine print on dichlorvos labels.

Some key label points to remember about Nuvan and similar strips:

  • Do not over-apply.  One 16 gm strip is sufficient for treating 100 to 200 cubic feet.  Having said that, do your technicians know how to estimate cubic feet?  A typical 6' by 12' by 8' walk-in closet is approximately 575 cubic feet (a simple multiplication of length x width x height) and would require 3 to 5 strips--6 would be an over-application.
  • Around the home, strips may only be used in closets, wardrobes and cupboards, storage units, garages, attics or crawl spaces. Other sites outside the house are also listed on the label.
  • Do not use in kitchens or food prep or storage areas where unwrapped food may be exposed.  Kitchen utensils should not contact the strips.
  • Pets and children should not play or sleep where strips are in use, nor should the strips be used in any room where humans are likely to spend more than four hours a day. An important sidenote here: most of the illnesses (65%) reported in the CDC paper occurred when exposures exceeded four hours per day.
If you or your technician encounters a customer using dichlorvos strips, you owe it them to make sure they understand the risk of the product and use it only after carefully reading and following the label.

And if you'd like to receive the Morbidity and Mortality Report for it's occasional pesticide and pest-related stories, you can subscribe here

No comments: