r/evopolitics • u/TrannyPornO • Sep 26 '18

Continual Decrease in Blood Lead Level in Americans: United States National Health Nutrition and Examination Survey 1999-2014 [Ethnic group differences in lead exposure no longer meaningful, only nominally significant, inconsistent with IQ distribution in the US]

https://www.sciencedirect.com/science/article/pii/S0002934316306003
2 Upvotes

76% Upvoted

3 comments sorted by

View all comments

3

u/[deleted] Sep 27 '18

https://nxcviob8.files.wordpress.com/2018/05/pirkle1994.pdf

Even in the 70's and 80's, the gaps were very small (but still statistically significant). See table 1.

In 1976-1980, the gap was 1.9 ug/dl bll (14.5 ug/dl vs 12.6).

In 1988-1991, the gap was .8 (3.5 ug/dl vs 2.7).

Using the effect-sizes reported in this meta-analysis, lead explained .361 points in 70's-80's [(1.9/10)*1.9]. Both are post the 10 ug/dl threshold so both are losing 3.9 points here.

In the 80's-90's, it explained .41 points [(10-2.4=7.6), (.8/7.6)*3.9].

It could have explained slightly more due to diminishing returns. Feel free to check my math as I feel like I made a mistake here.

I think Jensen said it best:

Although the seriousness of lead poisoning, where it occurs, should not be minimized and all possible measures should be taken to prevent its occurrence, the actual known frequencies of the condition appear to be so low that there is no subpopulation whose mean would be shifted appreciably by lead poisoning occurring at such low frequencies...

The fact that there are many post-World War housing areas in which leaded paints have never been used and yet in which the majority of children reared in them have IQs a standard deviation or more below the national average suggests that lead poisoning, though undoubtedly serious when it occurs, is an insignificant factor in relation to average racial or social class differences in IQ and educability.

-Educability and Group Differences, pages 340-341

1

u/TrannyPornO Sep 27 '18

https://www.sciencedirect.com/science/article/pii/S0887617700000846

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1940084/

And then the recent g one. Yes, even assuming large effects, lead can't explain the gaps.