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Lead is considered as one of the most toxic elements emitted into the atmosphere due to the combustion of gases and the automobiles has been regarded as the main source. Several workers have shown that atmospheric Pb levels are directly related to traffic volume and inversely related to the distance from highways.
This element enters into human body by ingestion, inhalation and in some cases by absorption through the skin. The contribution of atmospheric Pb to blood Pb has also been reported by several workers.
Experiments were conducted to determine the Pb concentration in blood and urine of Tehran’s population. Blood and urine lead levels are found to be closely related to traffic volume, and its level in blood increases progressively with age. Blood lead levels were also significantly higher in cancer patient as compared with others.