Lead in School Drinking Water: Canada can and should Address This Important Ongoing Exposure Source (Commentary) (Report‪)‬

The control of major historic sources of lead exposure, including leaded gasoline and residential paints, has lowered lead levels in children. US data indicate that the prevalence of blood lead levels (BLLs) [greater than or equal to] 10 [micro]g/dL among children 1-5 years of age decreased from 8.6% in 1998-1991 to 1.4% in 1999-2004, (1) while 2007-2009 Canadian data show that the geometric mean BLL of children aged 6-11 years was 0.90 [micro]g/dL. (2) Still, BLLs 10 [micro]g/dL have been linked to persistent deficits in intelligence as well as to neuropsychiatric disorders including antisocial behaviour. (3) A pooled analysis of seven prospective studies investigating the relationship between childhood lead exposure (from birth or infancy to 5-10 years of age) and full-scale IQ tests showed a log-normal dose-response relationship; a rise in BLLs from 20 to 30 [micro]g/dL was associated with a drop in mean IQ of 1.1 points (95% CI, 0.7-1.5), a BLL rise from 10 to 20 [micro]g/dL was associated with an IQ deficit of 1.9 points (95% CI, 1.2-2.6), and a BLL rise from 2.4 to 10 [micro]g/dL was associated with the greatest deficit of 3.9 IQ points (95% CI, 2.4-5.3). (4) The observation of health impacts at lower levels of blood lead, and the demonstration that even small reductions in BLL can have important population-level health gains, stresses the need to address continuing residual exposure sources. It has been argued that the mitigation of ongoing lead sources is strongly cost-beneficial. In the US, researchers estimated that a mean decline of 15 [micro]g/dL in children aged 1-5 years between 1976 to 1999 resulted in a gain of 2.2-4.7 IQ points per child; this gain was in turn estimated to result in economic benefits of $110-$319 billion, through increased productivity and higher lifetime earnings. (5) Although no cost-benefit analysis for drinking water could be identified, it is reasonable to assume that economic benefits would likewise accrue with the reduction of lead in school drinking water. Children are exposed to lead through school drinking water