Lead (or Pb in the periodic table) is a naturally occurring heavy metal that is found in the Earth’s crust. Humans have used lead in various applications for hundreds of years without knowing the health hazards of lead. The main natural sources of lead are mining, soil erosion, volcanic eruptions, sea sprays and bush fires. The anthropological sources are too many as the lead is an indispensable metal.
Paints: Lead was used in paint to add color, to hide the wall surface it colors, and to make the paint last longer. In 1978, the Federal Government banned the use of lead paints. But lead can be found in the old paints which mixes with air and sioil during renovation works of old houses.Lead paint is not prohibited in India. A 2015 study found that over 31% of household paints in India had lead concentration above 10,000 parts per million (ppm), which far exceeds the BIS standard of 90 ppm for lead in paint. According to CSE, India report deep orange and yellow colored paints have obnoxious amount of lead in them. Few companies in India have tried to reduce lead content but others are least bothered to follow the toxicity norms. Hence the workers in paint industries are at high risk.
Lead paint or lead-based paint is paint containing lead. As pigment, lead(II) chromate (chrome yellow), Lead(II,IV) oxide, (Pb3 O4, “red lead”), and lead(II) carbonate (“white lead“) are the most common forms. Lead is added to paint to accelerate drying, increase durability, maintain a fresh appearance, and resist moisture that causes corrosion.
Dust: Lead dust is the most common way that people are exposed to lead. The old paint chips, flakes mix with soil very easily during repainting or remodeling of the old houses. Even demolition of old buildings, houses helps the dust to get contaminated with lead. Lead gets transferred to our body while we bump onto the painted walls or rub against it, the door and window paints too are easily accessible to humans especially children who like to write and draw on painted surfaces.
Soil: Lead from car exhausts mixed with soil near roads are still there today. Homes near busy streets may have higher levels of lead in the soil. Lead in air and soil comes from metal smelting, battery (Lead-Acid) manufacturing, and other industries that use lead like cement, iron-steel, ceramic industries,petroleum, coal products, glass products, motor vehicles and their parts etc.Once the soil has lead in it, wind can stir up lead dust and blow it into homes and yards.
Drinking Water: Lead enters drinking water supplies due to corrosion of materials containing lead. For examples, the pipes have joints made up of an alloy called solder metal (40% PB, 60%Sn). Though there is a cut down in using solder metals in plumbing joints, still there are older pipelines which can contaminate drinking water with lead.
Air: Lead can be present in outdoor and indoor air. Lead in outdoor air comes mainly from smelters, waste incinerators, battery manufacturing units. Wind blown soil and road dust also may contain naturally occurring lead as well as lead from industrial sources, deteriorated paints, and the combustion of leaded gasoline as surface and aviation fuels. Indoor air gets lead from suspended particles, paint chips from walls, stained glass objects with lead solders and from lead bullets at indoor firing ranges.
Other Sources: Lead may be present in toys, cosmetics like lipsticks, kohl, hair colors; traditional medicines(Ayurveda, uses are more in India), spices, vegetables(if the soil contain lead). Lead is also found in the food storing containers made up of ceramics, bone china, lead glazed utensils. Lead solders are used in food cans. Over the time lead gets into the food. This happens faster after the can has been opened. Lead gets into the air fro plumbing, welding, painting and refinishing, manufacture of rubber products, from brass and bronze factories, fishing tackles., glass and metal products, colored yarns, fabrics, motor vehicles and their parts, wood products etc.
The sources of lead in air, water and soil are plenty. Enlisting them is a herculean task.
Lead paint is hazardous. It can cause nervous system damage, stunted growth, kidney damage, and delayed development. It is dangerous to children because it tastes sweet, therefore encouraging children to put lead chips and toys with lead dust in their mouths. Lead paint is dangerous to adults and can cause reproductive problems in men or women. Decreases in sperm production in men have been noted. Lead is considered a possible and likely carcinogen. High levels may result in death.
Health effects of lead poisoning on children
Lead exposure can have serious consequences for the health of children. At high levels of exposure, lead attacks the brain and central nervous system to cause coma, convulsions and even death. Children who survive severe lead poisoning may be left with mental retardation and behavioral disorders. In particular lead can affect children’s brain development resulting in reduced intelligence quotient (IQ), behavioral changes such as reduced attention span and increased antisocial behavior, and reduced educational attainment. Lead exposure also causes anemia, hypertension, renal impairment, immunodeficiency and toxicity to the reproductive organs. The neurological and behavioral effects of lead are believed to be irreversible.
There is no known safe blood lead concentration. But it is known that, as lead exposure increases, the range and severity of symptoms and effects also increases. Even blood lead concentrations as low as 5 µg/dL, once thought to be a “safe level”, may be associated with decreased intelligence in children, behavioral difficulties, and learning problems.
Encouragingly, the successful phasing out of leaded gasoline in most countries, together with other lead control measures, has resulted in a significant decline in population-level blood lead concentrations. There are now only 3 countries that continue to use leaded fuel . More, however, needs to be done regarding the phasing out of lead paint: so far only one third of countries have introduced legally binding controls on lead paint.
Burden of disease from lead exposure
The Institute for Health Metrics and Evaluation (IHME) estimated that in 2016 lead exposure accounted for 5,40, 000 deaths worldwide due to long-term effects on health. The highest burden was in low- and middle-income countries. IHME also estimated that in 2016, lead exposure accounted for 63.8% of the global burden of idiopathic developmental intellectual disability, 3% of the global burden of ischemic heart disease and 3.1% of the global burden of stroke.
- Phasing out of leaded petrol helped to reduce lead pollution. It should be completely banned throughout the world.
- Phasing out of leaded paints is need of the hour.
- Creating awareness will help parents to keep away their children from glittered toys. Special care must be taken for young who has a habit of putting everything in mouth
- The factory workers must be trained to avoid contamination by using lead masks.