With spring temperatures rising also comes the rise of little springy things called fleas. Flea shampoos are often used to control fleas but a recent study has found that mothers of autistic children were twice as likely to have washed their pet dog with pyrethrin containing anti-flea shampoo during the months prior to delivery.
Of course these findings only demonstrates a correlation, they do not prove a cause. Pyrethrins are naturally occurring compounds that are derived from Chrysanthemums. Pyrethroids are the synthetic version. They are both neurotoxins that over excite nerve cells and cause death in insects. Be careful if you use them. While they are toxic to pest insects, they are also toxic to fish and tadpoles and beneficial insects like bees. But, because they work well and are low in toxicity to humans, birds and mammals they are have largely replaced other pesticides like organophosphones for flea control.
They rapidly break down outdoors in sunlight, which is another favorable quality of pyrethrins. But, they can persist indoors on floors and carpets and on the coats of indoor pets treated with pyrethrin containing flea shampoos. This increases human exposure to this chemical and could explain why household pyrethrin use is correlated to increased findings of autism spectrum disorder.
What to do?
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