OK, very much preliminary findings but:
Chemicals found in pet shampoos may be linked to a raised risk of autism, a study of how environmental factors influence the developmental disorder has suggested.
Mothers who used pesticide-based shampoos to wash their pets while pregnant were twice as likely to have a child with an autistic spectrum disorder as those who did not, according to early results from a US research team.
Hedged around with all sorts of "preliminary", "confirmation bias" and so on. However, it does fit in with what seems to be the best explanation of the causes of autism, the idea put forward by Simon Baron Cohen.
I\’ll leave aside all the details and point just to the actual mechanism he posits: that it\’s the influence of testosterone upon the developing foetus. If these pesticides do indeed change the levels of such in the mother\’s bloodstream (hmm, not sure, does testosterone cross the placental boundary?) then it all fits neatly together.
One thing should be noted though: Baron Cohen thinks that genetics (the rise of assortative mating) is the primary driver of the rise in cases: but he\’s never ruled out the thought that there could be environmental triggers as well. Given that autism is actually a diagnosis of symptoms (in the same way that "cancer" is) rather than a specific disease, there\’s no reason why there can\’t be both, genetic causes and environmental: there could be cases caused solely by either plus those caused by the interplay.