Take a look at the link, it's relevant to your question. As mentioned there, your body stores lead in your bones, which leeches into your blood stream. Because

Take a look at the link, it's relevant to your question. As mentioned there, your body stores lead in your bones, which leeches into your blood stream. Because there does not appear to be a minimum safe threshold of exposure, even small exposure can, over time, lead to problems as the lead is circulated through your body, as mentioned in the quote. Sorry it doesn't appear clear when taken out of context.