Nor would I. I still believe that autism is about toxic load but the chemical changes that could occur when mother is stressed could explain some things. Stress will produce adrenaline, the flight or fight hormone. This could mean PPD kids bodies could have built up a tolerance to chemical danger responses, and just like how a drug addict needs bigger and bigger doses to get high, the level of toxic substances they are exposed to have to be fairly high before their system reacts them. Therefore, if the substances are on the smaller side, they hold on them rather than process them because their bodies haven't recognised the threat. Just thinking out loud...