"Today the continuing poisoning of half a million American children is tolerated partly because the victims often are low-income children of color."

I think it is outrageous for the writer to make this claim.  Lead poisoning is tolerated because by and large it is invisible and is not routinely detected.  Until a few years ago, copper pipe used to disperse water throughout our buildings was joined with lead containing solder.  Probably most houses in the country have lead in their pipes.  When water is not used often lead from the solder can dissolve and reach appreciable concentrations.  

The big thing about lead is that it takes really high doses to produce obvious symptoms.  To some extent low dose exposures are not obviously connected to harm.  The whole subject is controversial.  Run your water a bit before drinking it to flush the high lead content out.