When lead is absorbed into the body, it is quickly taken up by bone and is tightly bound. It is then slowly released into the circulation keeping the blood level elevated for years. The time frame depends on the lead burden; the larger the burden, the longer the time that lead will be released into the bloodstream, and continue to elevate the blood lead level.
When children’s lead levels are analyzed sequentially over time, the typical peak is at 18 months of age. This is because children around that age are crawling on the floor to explore their environment which, if contaminated with lead paint chips, are then ingested. After 18 months of age, children are walking (rather than crawling) and thus off the floor, exploring other environments. As a result, they are not as readily exposed to lead paint chips from which they can be poisoned. Thus, on average, children older than 18 months are less likely to have elevated blood lead levels and children who had elevated blood lead levels from a prior exposure will see their levels decline.
Lead absorption medical expert witness specialties include pediatric endocrinology, pediatric neurology, and neuropsychology.