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Autism has also been linked to maternal age. Maybe older women just happen to also have more DDT because they had more time to accumulate it or they were alive longer for when DDT was widely used.

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The study controlled for that:

> The odds of autism among offspring were significantly increased with maternal p,p'-DDE levels that were in the highest 75th percentile, with adjustment for maternal age, parity, and history of psychiatric disorders...

They also could/should have adjusted for paternal age, which may be a significant factor (see [1] for lots of links). (There is some interesting statistical stuff going on with paternal age -- some researchers claim if you bin by birth year some of the paternal effect disappears, which is odd! However, the article under discussion considers only children born between 1987 and 2005, so it's not a huge range of birth years...) They do have data on paternal age, but they don't include it in Table 1. Odd.

[1] https://www.spectrumnews.org/news/link-parental-age-autism-e...

Presumably they at least controlled for age race and socioeconomic level. If they didn’t then the results are very suspicious.

"Adjusted for maternal age, parity, and maternal history of psychiatric disorders"

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