IQ and pollutants:

http://www.lemonde.fr/sciences/article/2014/12/01/pollution-l-intelligence-des-prochaines-generations-est-en-peril_4532272_1650684.html

http://www.lemonde.fr/medecine/article/2014/12/10/la-pollution-met-en-danger-le-cerveau_4538177_1650718.html#xtor=AL-32280270

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0114003#pone-0114003-t002

and tobacco smoke

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4181918/