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Comment by xyzzyz | Hacker News Reader

What are other important environmental factors affecting IQ in first world? I haven't really heard of any other are as important as these, so I'm interested in learning about them.

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There are many environmental poisons that affect brain development, consumption of lead, for instance. Also there are many diseases that can effect brain development, such as congenital syphilis.

Are these significant in the first world though? I thought that phasing out leaded gasoline and lead paint happened enough time ago to not be a significant factor anymore these days. Similarly, congenital syphilis prevalence is not high either, especially as syphilis is quite easy to treat today.

Well, there is the continuing mass lead poisoning in Flint - http://time.com/5197427/flint-water-samples-lead-increase/ - and congenital syphilis is on the rise in the USA - https://edition.cnn.com/2017/03/01/health/syphilis-newborns-...

Flint isn't anywhere close to unique in lead exposure, though it gets the most media attention. See, e.g., https://www.scientificamerican.com/article/lead-poisoning-af...

Based on your article, congenital syphilis is extremely, extremely rare. Lead poisoning seems to also be rather low, compared to 50 years ago. I know these two things happen. I asked if they are significant. Seems like they are not.

On their own, maybe not. If taken as examples of two classes of environmental effect, namely environmental toxins and transmissible diseases, I would be surprised if those two broad types did not have a significant effect on the variability of developmental IQ in rich countries.

> Lead poisoning seems to also be rather low, compared to 50 years ago

Overall exposure is lower, sure, that doesn't mean it is insignificant in impact on IQ (and other health issues, notably cardiovascular disease.)

> I thought that phasing out leaded gasoline and lead paint happened enough time ago to not be a significant factor anymore these days.

No, lead exposure from water systems, unabated older housing, continued use of leaded aviation fuel, and other sources continues to be a nontrivial issue in the US and some other parts of the first world.

Don’t forget the most obvious: diet, both of the pregnant, mother, and the growing child. The link between insufficient nutrition and lowered IQ is well established.

https://www.ncbi.nlm.nih.gov/pubmed/2628311

https://www.sciencedaily.com/releases/2004/11/041117005027.h...

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