Lead is one of the most important heavy metals to threaten human health and ecological balance. Exposure to lead due to occupational necessity or for various reasons creates toxic effects on cells. There are generally three forms of lead in the environment, metallic lead, lead salt, or organic forms containing carbon. Damage caused by lead in living systems after exposure to free radicals involves two different mechanisms. Lead causes tissue and organ damage by inhibiting two important enzymes, such as delta-aminolevulinic acid dehydratase (ALAD) and glutathione reductase (GR).
Lead exposure occurs mostly through the gastrointestinal system, respiratory system, and skin. After lead is taken into the body, it binds to hemoglobin at a rate of 99% and is distributed mainly in soft tissues. Low dietary calcium content is an important factor that increases lead absorption. Lead vapor and dust reach the lungs through the respiratory tract and pass from the lungs into the blood. Respiratory exposure is very important in lead poisoning.
Lead exposure is known to increase the risk of lung infections and cancer. Lead exposure can adversely affect the nervous system, especially the central and peripheral nervous systems. Fetal lead exposure in the early stages of life has been reported to cause neurodegeneration in postnatal life.