Other things that have increased in the past 20 years that may have a link to autism:

Population of California condors
# of IPODS per capita
Starbucks franchises
Cars named after abstract concepts
Thongs
Stray cat population
Time outs as opposed to spanking
# of pussycat dolls
microbreweries
paint colors
varieties of mints
highways
sunny days in pittsburgh (from 55 to 57)
skateboarders
ice cream flavors
kinds of meat you can turn into jerky
# of times Robert Downey Jr. has entered rehab

This is tongue in cheek if you can't tell but it's a serious topic. Personally I think the rise in autism spectrum disorders incidence is due to increased awareness and diagnosis. The reason why it's considered a spectrum is because of the varied severity in impairment. Some kids are very high functioning, but just have some behavioral issues or inability to appreciate social cues. Some cannot use language in the conventional sense. I'm sure many people who did not get diagnosed were treated went on to either grow out of, or learn to cope with their disorder. Think of the eccentric uncle you have who can invent a better lightbulb but who doesn't like loud noises and personal contact. There is probably a multifactorial cause for autism spectrum disorders, genetic predisposition, environmental factors, toxicity, emotional support, trauma, less time with parents, etc. My point with the above list is that there are many people who try to pin all cases of autism and aspergers on a single entity, whether it be vaccines or mercury or power lines or bad parenting or rock n' roll or now sunlight. Could sunlight be a factor? Sure, it's possible, I'm not discounting that. Just like I don't discount vaccines or mercury, etc. However, you can take MANY things and make a graph and say, "hey, you know what, X has increased steadily, just like cases of autism and asperger's, they MUST be related!" The question is whether it's just a coincidence or in fact a causal factor. Unfortunately kids don't live in a vaccuum, and it is very difficult to conclusively decide yes or no with a single factor. Compound this with the fact that it's such a sensitive issue, in that parents with children affected by these problems go through more than anyone can ever imagine who does not take care of similarly affected children. Their child has a problem, and something/someone must be blamed. I think it's good that awareness has increased and research being down to unravel the mystery of autism but I think it's irresponsible to continually cite a cureall/single causal factor. Maybe it's this!!! Hmm..ok maybe it's this!!! Well, sorry, how about this!!!
However, at least in this case, there's no real danger to a little bit more sun exposure responsibly, (smoke em if you got em pittsburgh), and most people are probably deficient in vitD and calcium anyway.

Sunlight exposure has been linked to a healthy immune system in previous studies. In the office where I practice we receive a weekly publication "Science News" that has an article in the July 28 issue titled "Good Light: Sun early in life could protect against MS".

A few excerpts from this article:

"A half-century ago, doctors from Europe and North America who spent time in central Africa were struck by the absence of multiple sclerosis there. Indeed, the farther from the equator people lived, the more prevalent multiple sclerosis (MS) seemed to become. Scandinavians faced a higher risk than most other people. Thus arose the "latitude hypothesis" of MS, suggesting that a lack of direct sunshine somehow contributed to the nerve-damaging immune malfunction underlying the disease."
...

"The study bolsters a 2003 report from Australia that associated greater sun exposure and a history of sunburns in childhood with reduced risk of MS."
...

"This is a very sound piece of work," Goldacre says. "Dermatologists may feel that [advice to] spend some time in the sun is not a wholly welcome message. But it's all a matter of this being good for you in small doses."

So if lack of sunlight plays a role in preventing the development of MS, it doesn't seem unreasonable to me that it may also play a role in preventing other unnatural conditions such as autism.

One thing is for sure, over the past couple of decades many people, (me included), have gone to extrordinary means to avoid exposure to sunlight, especially by using sunscreens.

And Vitamin D in vitamins is toxic in large doses. The body can produce a form of Vitamin D in very large amounts as a result of exposure to sunlight that is non-toxic. The important thing is to find the right balance, and you won't find that in a tanning salon.

Valerie