What percentage of lead is stored in the bones?

The correct answer highlights that approximately 90% of lead in the human body can be found stored in the bones. This significant percentage is critical to understand when evaluating the long-term effects of lead exposure. When lead enters the body, it can substitute for calcium in bone tissue, leading to an accumulation over time. This stored lead in bones can be released back into the bloodstream during periods of increased bone turnover, such as pregnancy or after certain types of bone injuries, potentially leading to health risks.

Understanding that a large portion of lead resides in the bones underscores the importance of monitoring lead exposure levels and instituting prevention strategies in environments where lead is present, as even small exposures can lead to accumulation and subsequent health issues later on.

The other options suggest lower percentages of lead storage, which would not reflect the current understanding of lead bioaccumulation and its long-term residence in bones. This contextual knowledge about lead storage informs public health strategies aimed at reducing exposure and protecting at-risk populations.