Editing Neuroscience and intelligence (section)

== Health ==
{{main|Impact of health on intelligence}}
{{main|Cognitive epidemiology}}
Several environmental factors related to health can lead to significant cognitive impairment, particularly if they occur during pregnancy and childhood when the brain is growing and the [[blood–brain barrier]] is less effective. Developed nations have implemented several health policies regarding nutrients and toxins known to influence cognitive function. These include laws requiring [[food fortification|fortification]] of certain food products and laws establishing safe levels of pollutants (e.g. [[lead]], [[mercury (element)|mercury]], and organochlorides). Comprehensive policy recommendations targeting reduction of cognitive impairment in children have been proposed.<ref name="Olness">{{cite journal | last1 = Olness | first1 = K. | year = 2003 | title = Effects on brain development leading to cognitive impairment: a worldwide epidemic | pmid = 12692458 | journal = Journal of Developmental and Behavioral Pediatrics | volume = 24 | issue = 2| pages = 120–30 | doi=10.1097/00004703-200304000-00009| s2cid = 31999992 }}</ref>