Trace elements as paradigms of developmental neurotoxicants: Lead, methylmercury and arsenic

Abstract

Trace elements have contributed unique insights into developmental neurotoxicity and serve as paradigms for such adverse effects. Many trace elements are retained in the body for long periods and can be easily measured for the purpose of exposure assessment by inexpensive analytical methods of analysis that became available several decades ago. Thus, past and cumulated exposures could be easily characterized from analysis of biological samples, such as blood and urine. Compelling evidence resulted from unfortunate poisoning events that allowed for the scrutiny of long-term outcomes of acute exposures that occurred during early development. This documentation was followed by prospective studies of child cohorts examined with sensitive neurobehavioral methods, thus leading to an understanding that the brain is unique vulnerable to toxic damage during early development. Lead, methylmercury, and arsenic thereby serve as paradigm neurotoxicants that provide a reference for other substances that may have similar adverse effects. Less evidence is available on manganese, fluoride, and cadmium, but experience from the former trace elements suggest that, with time, adverse effects are likely to be documented at exposures previously thought to be low and safe.