Though we all know that nature has provided us with many vitamins, minerals and variety of trace elements that are necessary for our survival, however, little we know that there are certain natural elements and heavy metals that are poisonous to our bodies in any form and even in trace amount. Lead is one of those heavy metals that is hazardous to various normal body functions even if ingested or inhaled in minute quantity.
Lead, a highly toxic substance, produces chronic Lead Poisoning once it starts accumulating in the body. The lead poisoning can affect almost every major physiological system and psychological processes in the body including learning and behavioral patterns. Unlike other elements and heavy metals like zinc, iron, cobalt, selenium and chromium, lead serves no known or useful function in the body. Infact it serves the opposite by settling permanently in bones, brain and other tissues. It blocks nerve cell communication, disrupt heart rhythm, increases blood pressure, reduce artery elasticity and interfere with genetic and reproductive functions. At very high levels in blood, it can even result in coma leading to death.
According to the Center of Disease Control (CDC), a blood lead level (BBL) greater than 10 micrograms per deciliter of blood (10ug/dl) can cause adverse health effects. Lead poisoning is a global threat effecting both the developed countries as well as the developing countries. Approximately 434,000 children in US age 1-5 years, 1 in every 10 children in UK under 6 years, 75,000 children in Australia under 5 years, 1 in every 20 children in France and Canada and 51.4% children under 12 in India have found to be carrying greater than the recommended blood lead level. In 1970s, the average lead level in the population was 14ug of blood and 15% of the population had levels from 20-29 ug and above.
The major source of lead exposure among children is lead based paints, lead contaminated dust found in old buildings and lead coated toys. Lead based paints were banned for use in housing in US in 1078, almost 64 years after it was first banned in Australia in 1914. Unfortunately, according to the US Department of Housing and Urban development (HUD), there are approximately 38 million houses in the US that still contain some lead paint. People living in old buildings that were built before 1978 should use detergents that contain phosphates as they bind with lead and help in removing lead dust particles from the floors.
Another major source of lead exposure was the old water pipelines that shed traces of lead in water used for drinking, cooking etc. These plumbing pipelines were made with lead or copper pipes that were joined with lead solder.
The Toy Manufacturers of America (TMA) together with American Academy of Pediatrics, jointly developed the first toy safety standard after the protest that the toys sold in US cities contain hazardous levels of heavy metals, lead and cadmium.
Lead, a potent toxicant known to alter neurological, reproductive, renal and hematological systems of the body, greatly affected specially the children worldwide because the children being still developing had higher risk of potential damage to their vulnerable systems. Low levels of lead in the body when a child’s brain is developing can slow it’s development, cause learning and behavior problems or produce mental retardation. Elevated levels of lead in blood is a decrease in Intelligent Quotient (IQ) levels.
Lead is a widely used metal in various industries for it’s low melting point, greater ability to form carbon metal compounds, holding pigments well, easy recycling ability, high degree of corrosion resistance easy availability and inexpensive cost. It is still used in the manufacturing of water heaters, pottery with lead glaze (ceramics), polythene plastic bags, cardboard boxes with dyes, lead based glass paints, lead beads, lead crystal glasses and cheap lead jewlery. Bioaccumulation of lead in soil , water and air by steel industry and lead arsenate in fertilizers are another sources of lead in the environment. Leaded gasoline was band in 1986 but in developing countries, vehicle emissions in cities at present account upto 90% of airborne lead.. Candle wicks with lead can release lead when burned and results in lead inhalation.
Approximately 10 years ago, a major hazard in pencils was from lead chromate paint on the exterior of yellow pencils. Now pencils are made with graphite which is not a hazard to health.
Lead though remains a global hazard, it’s effective uses in various industries can not be ruled out.
Caution is greatly needed when living in a lead filled environment.