Science Library Category:

Intelligence-IQ

Published: 2020
SYNOPSIS

PBDE (chemicals from Flame Retardants) exposure was the greatest contributor to intellectual disability burden, resulting in a total of 162 million IQ points lost and over 738,000 cases of intellectual disability.

TITLE

Trends in neurodevelopmental disability burden due to early life chemical exposure in the USA from 2001 to 2016: A population-based disease burden and cost analysis

CITATION

Abigail Gaylord, Gwendolyn Osborne, Akhgar Ghassabian, Julia Malits, Teresa Attina, Leonardo Transande; Molecular and Cellular Endocrinology; Online: 14 January 2020. doi 10.1016/j.mce.2019.110666.

SUMMARY

Endocrine disrupting chemicals are known to cause neurodevelopmental toxicity through direct and indirect pathways. In this study we used data from the National Health and Nutrition Examination Surveys, along with known exposure-disease relationships, to quantify the intellectual disability burden attributable to in utero exposure to polybrominated diphenyl ethers (PBDEs commonly known as Flame Retardants), organophosphates, and methylmercury and early life exposure to lead. We also estimated the cost of the IQ points lost and cases of intellectual disability. PBDE exposure was the greatest contributor to intellectual disability burden, resulting in a total of 162 million IQ points lost and over 738,000 cases of intellectual disability. This was followed by lead, organophosphates, and methylmercury. From 2001 to 2016, IQ loss from PBDEs, methylmercury, and lead have decreased or remained stagnant. Organophosphate exposure measurements were only available up to 2008 but did show an increase in organophosphate-attributable IQ loss. Although most of these trends show benefit for children’s neurodevelopmental health, they may also point towards the use of potentially harmful substitutions for chemicals that are being phased out.

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Published: 2019
SYNOPSIS

Lower IQ in children is strongly associated with higher levels of maternal fluoride exposure during pregnancy.

TITLE

Association between maternal fluoride exposure during pregnancy and IQ scores in offspring in Canada

CITATION

Green R, Lanphear B, Hornung R, et al. JAMA Pediatrics. 2019;173(10):940-948.

SUMMARY

In this Canadian study, maternal exposure to higher levels of fluoride during pregnancy was strongly associated with lower IQ in children. In addition, the study found that women living in areas with fluoridated tap water had significantly higher average concentrations of fluoride in their urine compared to women without fluoridated tap water. Fluoridated cities in Canada use the same fluoride concentration (0.7 milligrams per liter) as the U.S. has used since 2015—a concentration recommended by the CDC as “optimal.” The authors raise concerns about the safety of maternal exposure to “optimally fluoridated water” and note that, at the population level, their results translate to “millions of IQ levels lost.”

 

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Published: 2007
SYNOPSIS

Test scores among young men declined between 1998 and 2003/04.

TITLE

Secular declines in cognitive test scores: A reversal of the Flynn Effect

CITATION

Teasdale TW, Owen DR. Intelligence. 2008;36:121–126.

SUMMARY

Scores on cognitive tests have been very widely reported to have increased through the decades of the last century, a generational phenomenon termed the “Flynn Effect” since it was comprehensively documented by James Flynn in the 1980s. Data reported here from young adult males in Denmark show that whereas there were modest increases between 1988 and 1998, scores on all four tests declined between 1998 and 2003/2004.

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