The effect of chelation on bone Pb stores in Pb poisoned children.

Background: Lead exposure remains a key problem for children during development. One treatment for lead poisoning is chelation - a topic that remains controversial with varied results. Bone lead serves as a marker of total body burden of lead and encompasses between 60-90% of lead storage in children.

Objective: In this study, we aimed to identify the change in bone lead as a result of chelation therapy in a group of lead poisoned children (blood lead >25 µg/dL).

Methods: Upon diagnosis with lead poisoning at Xinhua Hospital in Shanghai, China, children were recruited to our study, had their bone lead levels measured, and underwent one-week of intravenous, in-patient ethylenediaminetetraacetic acid chelation treatment. Up to three clinical visits with the same treatment protocol and bone lead measurements were completed over the two-year study. We measured biomarkers of lead exposure for children exposed via various potential sources, including home contaminants, local industrial emissions, traditional medicines, or lead cookware.

Results: We observed significant differences with bone lead after chelation therapy (p < 0.0001), even after calculating a conservative model for theoretical decay from known bone turnover (p = 0.01). The difference identified between our observed change in bone lead and literature established bone lead change significantly increased with more chelation treatments. A significant reduction in bone lead was observed following chelation treatment of children with lead poisoning - a difference that increased more with more chelation.

Significance: Study results indicate that chelation treatment is effective in reducing bone lead stores in children with initial blood lead levels greater than 25 µg/dL.

Impact statement: Lead exposure in children is a consistent problem - drastically impacting health across the life span. After exposure, lead stores in the bone of children serving as a potential endogenous source of exposure for years to decades. Our study demonstrated that chelation therapy, while reducing blood lead levels, additionally reduced bone lead levels. A reduction in bone lead would effectively reduce the potential for endogenous release of lead and restrict the damage done by lead exposure.