Abstract

Scientists working in the laboratories of the Bangladesh Atomic Energy Commission using proton induced X-ray emission spectroscopy have found that during the low rainfall season, the quantity of lead in Dhaka's air is 463 nanogram per cubic meter. Similar work in other parts of the world have found lead concentrations of 383 in Mexico City, 360 in Bombay, 333 in Sydney, 230 in Santiago, 70 in Los Angeles, while in Kyoto the presence of lead in air is at 40, the lowest.

Lead poisoning, or Plumbism, is the deleterious effect of gradual accumulation of lead in bodily tissues as a result of repeated exposure to lead containing substances. Lead has long been recognized as a neurotoxin. Scientific evidence have shown that lead retarded mental and physical development of children, causing reading and learning disabilities, hearing loss, hypersensitivity, behaviour abnormalities and reduced attention even at low levels of exposure. In adults, exposure to even low concentrations of lead, occurring usually through inhalation, has been demonstrated to result in anaemia and hypertension, resulting in an increased risk of cardiovascular diseases. The poison affects the entire body-specially nervous system, gastrointestinal tract and blood forming tissues. Among children the brain itself may be affected, resulting in some cases permanent damage, such as blindness, deafness, or convulsions and coma, ending in death. Brain injury may also occur in adults after massive exposure.

In Bangladesh, because of the use of leaded gasoline and consequent deliberate pumping of exhaust emissions into atmosphere, vehicular traffic remains the single largest source of environmental lead pollution in most urban areas, accounting for over 90 percent of' all lead emissions. Besides posing an immediate health risk through inhalation, vehicular lead emissions also accumulate in soil, enter the food chain, contributing to exposures through ingestion over long periods of time.