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Lead (RR)

Lead (Pb) is an odourless, bluish-grey, lustrous metal that is malleable, ductile, and resistant to chemical corrosion. Lead occurs naturally in bedrock, soils, tills, sediments, surface waters, ground-waters, and sea-water. Lead is toxic in nature and on being exposed can cause several diseases to human body. The toxic effects of lead have long been well known, especially as regards acute forms of poisoning. “Too much lead can damage the nervous and reproductive systems and the kidneys, and can cause high blood pressure and anemia. Lead accumulates in the bones and lead poisoning may be diagnosed from a blue line around the gums. Lead is especially harmful to the developing brains of fetuses and young children and to pregnant women. High blood lead levels in children can cause consequences which may be irreversible including learning disabilities, behavioral problems, and mental retardation. At very high levels, lead can cause convulsions, coma and death.” (WHO)

Once lead is absorbed by the body, mainly through breathing and feeding, lead is not metabolized, but mostly expelled. Portion of lead compound settles into the tissues and notably:
•    in the blood, where it is carried almost exclusively by the erythrocytes
•    in mineral tissues (bones and teeth), where it deposits
•    in soft tissues (kidneys, bone marrow, liver and brain)

The presence of lead in the blood stream (inside the red blood cells and mostly linked to haemoglobin) provokes anaemia. This disease cannot be considered a symptom, but rather a delayed sign of lead poisoning. Through the blood, lead reaches all other tissues. Because of its capacity to "mimic" calcium, lead is stored in the bones and becomes a stable bone component, particularly in the case of insufficient calcium intake. This lead deposit may be mobilized and return into the blood stream under particular states of physiological stress (pregnancy, breast-feeding, diseases), but also as a consequence of greater calcium intake in the diet. This stable presence of lead in bones makes recovery from lead poisoning extremely slow, even when the toxic agent has been completely eliminated.

Study of Lead in Lipstick
National Report on Lead in New Enamel Household Paints in Nepal, 2013
Study of Lead in paint in Nepal
Double Standard (Lead in Paint), 2011