Intelligence gain and social cost savings attributable to environmental lead exposure reduction strategies since the year 2000 in Flanders, Belgium

Abstract

Background Recent lead (Pb) exposure reduction strategies enabled to lower children's blood lead levels (B-Pb) worldwide. This study reports the estimated intelligence gain and social cost savings attributable to recent exposure reduction based on reported B-Pb levels observed in adolescents sampled within the framework of the Flemish Environment and Health Studies (FLEHS, Belgium), i.e. in 2003-2004 (FLEHSI), in 2008-2009 (FLEHSII), and in 2013-2014 (FLEHSIII). Methods Intelligence Quotient (IQ) loss per 100,000 individuals - attributable to B-Pb above 20 mu g/L - was estimated based on widely accepted dose response functions between children's B-Pb and IQ (- 1.88 IQ points for a duplication in B-Pb from 20 mu g/L onwards; 95% Confidence Interval (CI): - 1.16;-2.59) and B-Pb exposure distribution parameters of FLEHS studies. The results were translated to the Flemish population of 15-year-olds. Given a 3-year time gap between subsequent sampling periods, the exposure distribution of each study was assumed 3 years prior to the study as well. Economic impact was estimated based on expected decrease in lifetime earnings (euro 19,464 per decreasing IQ point in 2018). Results The percentage of the adolescent population exceeding a B-Pb of 20 mu g/L decreased from 57% (FLEHSI) to 23% (FLEHSII), and even further to 2.5% (FLEHSIII). The estimated IQ loss per 100,000 individuals was 94,280 (95% CI: 58,427-130,138) in FLEHSI, 14,993 (95% CI: 9289-20,695) in FLEHSII, and 976 (95% CI: 604-1347) in FLEHSIII. This translates into a total loss of 378,962 (95%CI: 234,840-523,091) IQ points within the Flemish population of 15-year-olds between 2000 and 2014. Assuming that current exposure levels do not reincrease, the expected IQ loss during the subsequent period of 15 years is estimated to be maximally 10,275 (95%CI: 6363-14,182) points. Conclusions 7176 (95%CI: 4447-9905) million euro of social cost savings were achieved by Pb reduction strategies in Flanders over 15 years. If current exposure levels further reduce to B-Pb below 20 mu g/L for the whole population, social cost savings may increase up to 7376 (95%CI: 4571-10,181) million euro. Given the relatively low lead contamination in Flanders, the global impact of ongoing reduction strategies is expected to be tremendous.