Sure there is. Breathing in the air has a safe standard of .15 micrograms of lead per cubic meter. [https://www.epa.gov/lead-air-pollution/national-ambient-air-....].

A typical person seems to breath between 8-9 cubic meters of air per day. So 1.2-1.3 micrograms of lead per day via oral inhalation seems perfectly fine per the EPA.

And the body does excrete lead, just slowly.

actual zero anything is nonsensical in the real world.