I came across this article today. It's hard to believe that permethrin has been banned in UK and Europe, but we still continue to sell them over the counter here in the US. It also talks about how Permethrin can damage children before they are even born from mother’s exposure raised the cancer risk for infants. http://enewspf.com/latest-news/science/science-a-environmental/50886-scientists-determine-99-6-of-lice-resistant-to-chemical-treatment.html