And lead's not the only pollutant you may have to worry about
Because Schwartz goes on to say that other pollutants like mercury and some pesticides may well do the same thing. And while there is insufficient research on mercury to date, recent studies suggest pesticide exposure raises the risk for Parkinson's disease a decade or more after the time of exposure.
And while the idea that the health effects of exposure to certain toxins can occur many years after exposure is not new, scientists consider this to be an "emerging area" for research; citing the fact that it's commonly accepted that exposure to tobacco and asbestos can lead to cancer even decades later.
As Dr. Philip Landrigan of the Mount Sinai School of Medicine New York said recently, "It makes sense that if a substance destroys brain cells in early life, the brain may cope by drawing on its reserve capacity until it loses still more cells with aging." And only after the onset of the aging process would symptoms like forgetfulness or tremors appear.
A prominent example that's cited is the fact that infant mice exposed to PCBs initially show only small, subtle effects. But by old age significant damage in areas devoted to daily activities like movement and learning are observed.
And while virtually every American will have some levels of lead in their blood, the phasing out of lead in gasoline from 1976 to 1991 along with other measures has caused the average level of lead in the blood of American adults to fall 30% by 1980 and 80% by 1990. But that's no help to the millions of Americans exposed to the stuff long before the phase-out began, as high rates of lead exposure back when are apparently accelerating their mental decline as they age.