Water is rarely pure any longer. Unless water is tested before and after being purified by water filters which remove some but not all of the heavy metals, there is still lead in tapped water.  Furthermore, not all the water that enters our body comes from water purifiers.  Swimming pools, showers or baths are NOT purified.  Whatever is spread on the soils, or sprayed on crops (like lead arsenate pest controls during the 1960's), or in synthetic fertilizers (which have included mining wastes) may accumulate in agriculture.

"Lead is a cumulative poison, being stored in all tissues and organs and it is transmitted to the foetus (Calvery et al., 1938; Castellino and Aloj,1964). Evidence exists that children and pregnant women retain lead more readily than others owing to the presence of rapidly developing tissues with a high affinity for the metal (Anon., 1966)."

www.inchem.org/.../v068pr23.htm

Furthermore, since many cement kilns burn hazardous wastes as fuel, there is likely to be more lead in the air and in the clinker of cement, which can leach out or erode into the environment. Additionally, coal contains lead and other toxic metals. When mined, poisons migrate into ground and surface waters.  But when burned, toxins in coal, even so-called Clean Coal, become airborne and contaminate agriculture downwind and downstream.  Lead is prevalent in our environment as increasingly high rates.  

In the 1990's, Dr. Herbert Needleman and colleagues at Pennsylvania's University of Pittsbugh School of Medicine found that lead expsoure early in life is associated with increased risk for antisocial and delinquent behavior, high school failture and reading deficits in young adults.  In a paper published in the 7 February 1996 issue of the Journal of the American Medical Association, Needleman and colleagues estimated that 15% of delinquency is attributable to lead exposure. www.jstor.org/.../3455017

ADHD is  producing changes in children's behavior, temperament, and ability to learn.  The symptoms of which are at:

www.cdc.gov/.../symptom.htm

Since that time, ADHD has been on the rise.  Are their other risks causing the increase?  Or, could it be that more lead is prevalent in the environment from various sources.  In addition to paint, which was Dr. Needleman's concern, incinerators that burn products such as PVC, which use lead as a stabilizer, or the color red which uses a pigment from lead release lead and other poisons into the environment.  Lead is amongst the lesser known chemicals coming from coal fired power plants, so called waste-to-energy powerplants (or garbage incinerators), biomedical waste incinerators, and other incinerators. Burning transforms the heavy metal, lead, into gases or particulate matter which falls to earth and accumulates in agriculture and in the bone.

Plastics, especially PVC plastic is on the rise. And, through the 1990's, there were no plans to limit the use of lead in consumer plastics.  Now, with deregulation, it wouldn't surprise me that lead is again on the rise.

Children have consumed fruit juices and milk for thousands of years. And if they are the contributing factor, we would all be in a brain fog by now. I suspect that human activity from industrial chemicals and heavy metals are more the cause.