Polly: Paul Shattock OBE is a retired professor of Pharmacognacy at the Autism Research Unit in Sunderland, England. He has done a lot to contribute to the opioids theory of autism. (See http://osiris.sunderland.ac.uk/autism/aru.htm.) Dr. Shattock has suggested that the increased use of organophosphate pesticides might be contributing to the autism epidemic.  The switch from the older organochlorine insecticides to the organophosphate insecticides occurred largely between 1979 and 1982. California records show a dramatic increase in reported autism cases between 1979 and 1992 (birth dates). Is this rise due to the increased number of vaccines, or mercury poisoning, or pesticides, or to a combination of these? Hope for Autism through Nutrition The Health Forum—Book 5 42 Organo-phosphate pesticides cause paralysis by inhibiting certain enzyme systems. One of these pesticides, Diazinon, has been shown to seriously interfere with the metabolism of tryptophan in a way that might force tryptophan metabolism towards the IAG (Indolyl Acryloyl Glycine) route. Are these pesticides contributing to the increased IAG in the urine samples from the majority of people with autism, fibromyalgia, chronic fatigue and related disorders? In England, about 80% of those with autism or ADD/ADHD have high IAG levels. Increased IAG could contribute to increased intestinal permeability (leaky gut), and perhaps increased blood-brain-barrier permeability. Also, the precursor to IAG called IAA (indole acrylic acid) can degrade unsaturated fats.  These pesticides also interfere with the Th1 immune system, which is necessary to keep yeast, bacteria, viruses and protozoa under control.  Low dose chronic exposure can interfere with Gproteins. 
Pesticides and other environmental chemicals (ECs) can induce environmental illness. Dr. Bill Plapp suggests that the mechanism might be an interference with thyroid and/or an interference with the production of the retinoic acid and the retinol forms of vitamin A. Low levels of retinoic acid and retinol are found in these environmental illnesses. Dr. Plapp states:
Suspect ECs have one or both of two characteristics in common. Many of them mimic the structure of thyroid hormones and react with transthyretin, the protein that transports both thyroid hormones and vitamin A from storage sites to sites where they are needed. Examples are dioxin, PCBs, DDT and other chlorinated insecticides and the newer synthetic pyrethroids, all of which contain a phenoxybenzyl chemical structure similar to that of dioxin. Other ECs, particularly organophosphate, carbamate, and pyrethroid insecticides, are probable poisons of the enzymes that activate retinoic acid from its fat-soluble precursors, retinyl acetate and retinyl palmitate. 
These types of pesticides are everywhere. Some are stronger than others. They are used to control fruit flies, termites, ants, fleas, lice, and pests on food crops. They are used in schools, retail outlets, office buildings, forests (Christmas trees too), and every place we go. Fortunately, there are safe alternatives that will control head lice, fleas, and common pests in our homes, offices and schools. See http://www.safetouse.com, or phone (909) 372-9850.
In particular, I feel it is criminal to advertise and sell pesticides to control head lice when there are safe alternatives. There are enzymes for sale that are safe, and one can even use the dodecyl alcohol found in coconut oil to kill head lice. In the excellent book Home Safe Home, Debra Lynn Dadd suggests killing head lice by using soap or shampoo with coconut oil in it and leaving it on the hair for 30 minutes. (When I tried this, the shampoo left on for this long seemed to dry the hair too much. So I prefer to use just plain coconut oil.) There is also a very new product that does not dry out the hair. It is Paw Paw Lice Remover Shampoo. (Paw paw is a fruit.) The shampoo works on your pets’ fleas and ticks too. You can even use the shampoo around the garden to help control pests there. Just dilute it and put it in a spray bottle. (The extract of paw paw interferes with the respiration of the insects.) This paw paw extract can also be used as part of a herbal parasite cleanse. (Nature’s Sunshine makes the shampoo and herbal parasite cleanse. http://www.naturessunshine.com Or phone (800) 453- 1422.)
Exposure to certain pesticides can inhibit the breakdown of acetylcholine and lead to excess acetylcholine. Pesticides are even a suspect in the Autism Interventions 43 etiology of “mad cow” disease. The organophosphate pesticide called Phosmet binds to copper. The use of Phosmet as a dip for animals coupled with copper deficiency and surfeits of manganese might be the real cause of “mad cow” disease. The symptoms are the same. This theory was proposed by Mark Purdy, a farmer. The theory is gaining acceptance as a credible reason for the epidemic. (There is also a theory that mad cow is an autoimmune reactive disease following infection with a bacteria called Acinetobacter found in the “winter feeds”. )
If you want more information on pesticides, contact Beyond Pesticides/NCAMP, at 202-543- 5450, or website http://www.beyondpesticides.org.