Lice and Pesticide Resistance
Excerpts Steve Tvedten's book "The Best Control"
(Used here with permission.)

[Parents know that products aren't working - a lawsuit]
[Pests, Bugs and Other creepsy stuff Site Map]
[About Kleen Kill] * [About Not Nice to Lice] * [Product Catalogue] * [Safe2use Site Map]



Contemporary Pediatrics Vol. 15, No. 11 noted:  That in the UK, children treated for head lice four years earlier with pyrethroid compounds (permethrin and phenothrin) needed at least 16 to 20 times the usual dose to eradicate another infestation  Laboratory bred lice in this experiment died within two hours of exposure to 0.1% permethrin, but lice from the heads of children who had been exposed to pyrethroid products took as long as 72 hours to die.  In Israel, clinically significant resistance to permethrin occurred within 2.5 years of its introduction, a time span corresponding to approximately 40 generations of lice.  Perhaps the most striking increase in resistance to permethrin has been recorded in the Czech Republic, where the concentration of permethrin required to kill 90% of head lice increased by some 500 times between 1981 and 1992.

Christina Beckwith, Pharm D noted in her “Head Lice New and Improved?”:  The Harvard School of Public Health is conducting a US study to determine the incidence and extent of resistance and plans to publish their results.  Preliminary results, released by the NPA without the investigators permission, appear to indicate some US lice are resistant.  In a preliminary in vitro study with 209 lice from 57 children, 100% survived in petri dishes containing varying permethrin doses.

The Spring, 1996 issue of the National Pediculosis Association's (NPA) Progress noted that for the past year the NPA has been averaging 50 calls a day reporting commercial product treatment failure - in spite of this - the continued use of these toxins - dog flea and tick shampoos, lice sprays, kerosene and/or other dangerous alternatives including Lindane are (still) being used repeatedly. Lindane was the cause of at least 70% of the reported serious health reactions to lice poison shampoos. Lindane is described by its Manufacturer as a powerful contact and internal poison. Lindane has been banned in 18 countries and severely restricted in 10 others. The FDA recommends lindane only be used where other treatments are ineffective. The majority of treatment failures involved Nix® and Rid®. Children still have live lice right after the poison shampoo. In thousands of uses Not Nice to Lice® has controlled resistant lice/nits safely.

Note: Pyrethrum- or permethrin-based pediculicides should not be used by persons with asthma or that are sensitive to ragweed, should not be inhaled or swallowed or used near the eyes or allowed to come in contact with mucous membranes, e.g., the eyes, nose or mouth . Lindane has been identified as both neurotoxic and carcinogenic and is already banned in 18 nations around the world. No pediculicide poison should be used on infants, pregnant women or nursing mothers or on cut or abraded scalps. No poison should ever be used to "treat" lice twice if it failed the first time, clearly indicating the lice may, at the very least, be resistant or immune to that particular product/poison. There are no poisons in the Pestisafe® Not Nice to Lice® shampoo, Kleen Kill® enzyme cleaners or Kleen Kill® peppermint soap

(Web Mistress Note:  A little license was taken with title and some emphasis.  However, the content is correct as it appears in "The Best Control)