Lead poisoning is one of the most common diseases of toxic environmental origin and accounts for about 0.6% of the global burden of disease. Lead is a naturally occurring heavy metal found in the earth’s crust. It is soft, malleable, and melts at a relatively low temperature. It is easily moulded and can be combined with other metals to form alloys.
It is widely used in many products such as lead-acid batteries for motor vehicles, pigments, paints, solder, stained glass, lead crystal glassware, ammunition, ceramic glazes, jewellery, and toys and in some cosmetics and traditional medicines.
Mining, smelting, manufacturing and recycling activities, and the continued use of leaded paint, leaded gasoline, and leaded aviation fuel (in some countries) are important sources responsible for environmental contamination. Drinking water supplied through lead pipes or pipes joined with lead solder may contain lead. Widespread use of lead has resulted in to extensive environmental contamination and health problems in many parts of the world. Humans also suffer from lead intoxication through the food chain.
Lead is a cumulative toxicant (increasing in quantity in the body over many years) that affects multiple body systems (neurologic, hematologic, gastrointestinal, cardiovascular, and renal systems). Young children are more susceptible to toxic effects of lead and can suffer with permanent adverse effects on their health. Adults exposed to lead are at increased risk of developing high blood pressure and kidney damage. Exposure of pregnant women to high levels of lead can cause miscarriage, stillbirth, premature birth and low birth weight and malformations.
Lead has no essential role in the human body. No safe level of lead exposure has so far been established. Even blood lead concentrations as low as 5 µg/dl may result in decreased intelligence in children, behavioural difficulties and learning problems; therefore prevention from exposure is important. The phasing-out of lead from petrol is a major international public health achievement but still global consumption of lead is increasing because of increasing demand for energy-efficient vehicles.
Lead paint can cause a long-lasting hazard to health in all age groups. Since leaded paint is a continuing source of exposure in many countries, World Health Organization (WHO), along with the United Nations Environment Programme has formed the “Global Alliance to Eliminate Lead Paint”. Its broad objective is to promote a phase-out of the manufacture and sale of paints containing lead and eventually to eliminate the risks involved with such paints.
The Ministry of Environment, Forest and Climate Change (MOEFCC), Government of India has passed a notification in November 2016 as “Regulation on Lead contents in Household and Decorative Paints Rules, 2016" and has prohibited manufacture, trade, import as well as export of household and decorative paints containing lead or lead compounds in excess of 90 parts per million (ppm). Efforts should be made to create public awareness about precautionary measures to be taken to prevent lead poisoning.
Most individuals when exposed to lower levels of lead show no symptoms. When symptoms of lead poisoning appear they are non specific and cannot be differentiated. Lead can seriously affect health of children.
Symptoms may be related to gastrointestinal system, central nervous system, musculoskeletal and cardiovascular system.
Physical examination –
Lead is a heavy metal with a bluish-grey colour. It has a low melting point, and can be combined with other metals to form alloys. It is widely used in products such as pipes; storage batteries; pigments and paints; glazes; vinyl products; weights, shot and ammunition; cable covers; and radiation shielding.
Lead used for these purposes come from mined ores (primary) or from recycled scrap metal or batteries (secondary). Today, most of the lead in global commerce is secondary and is obtained from recycling lead-acid batteries. Improper recycling of used lead batteries causes environmental pollution and health damage.
People can get exposure to lead mainly through inhalation and ingestion.
The use of some traditional cosmetics and medicines can also result in lead exposure.
Young children have a higher risk for exposure because they have frequent hand-to-mouth activity, and they absorb lead more easily than do adults.
Toys are important source of children’s exposure to lead. Lead is a problem in toys for two reasons: (a) the toy may be painted with leaded paint; and (b) the toy itself is made of lead.
Children who work as scavengers, street vendors, car repairers and ship dismantlers are at increased risk of lead poisoning. (These children may also suffer from nutritional deficiencies, which further enhances the adverse effects and increases the absorption of lead).
An enormous amount of electronic waste is generated each year worldwide and large numbers of workers involved in separating lead, mercury and other metals from the waste for recovery and recycling are exposed to lead.
Lead stored in bones is released into blood during pregnancy and becomes a source of exposure to the developing foetus. Pica during pregnancy can cause maternal and fetal exposure to lead.
Workers (in industries that use lead) can bring home lead-laden dust on their clothes, shoes and vehicles, resulting in contaminated dust in their homes can cause lead poisoning in the spouses and children.
Lead paint that is peeling, chipping, chalking or cracked is a health hazard.
Symptoms of lead poisoning are not specific. The diagnosis of lead poisoning can be suspected if possible source of exposure to lead is found during routine questions such as peeling paint in old housings combined with such behavior in children as pica, chewing on surfaces, and placing nonfood items in the mouth or proximity to open burning of waste or recycling of car batteries. Symptoms may be absent in spite of significant poisoning. Routine assessment of nutritional and developmental milestones is performed in children.
Environmental investigation is carried out to identify potential sources of lead exposure.
Radiological investigation shows lead lines in the metaphyses of long bones (chronic poisoning).
Medical interventions and treatments vary depending on the confirmed blood lead level. Simply avoiding exposure to lead might be enough to reduce low levels of lead in blood.
In more severe cases chelation therapy is recommended. In this treatment a medication given by mouth / injection binds with the lead so that it's excreted in urine. (While chelating agents can bind to lead in blood, they are ineffective in removing lead from the deep bone stores).
Nutritional counseling is given about intake of foods containing calcium, iron and vitamin C. (Adequate iron is required to decrease lead absorption. Foods high in calcium will help to maintain adequate calcium bone stores and lead will not get stored in bones. Vitamin C is needed for the absorption of iron. Children with empty stomach absorb more lead than children with full stomachs).
Prevention is the best way to deal with lead poisoning. Protecting children from exposure to lead is important to lifelong good health. No safe blood lead level in children has been identified, even low levels of lead in blood have been shown to affect intelligence quotient (IQ), ability to pay attention, and academic achievement. The effects of lead exposure cannot be corrected. The most important step parents and others can take is to prevent lead exposure before it occurs (primary prevention).
Further efforts are required to continue to reduce the use and release of lead to reduce environmental and occupational exposures, particularly for children and women of child-bearing age. Interventions include eliminating non-essential uses of lead such as lead in paint, ensuring the safe recycling of lead-containing waste, educating the public about the importance of safe disposal of lead-acid batteries and computers, and monitoring of blood lead levels in children, women of child-bearing age and workers.
Secondary prevention focuses on the early detection of lead poisoning. Secondary prevention strategies work to reduce the effects of lead in patients with identified elevated blood lead levels (EBLL’s).
World Health Organization (WHO) and the United Nations Environment Programme jointly initiated the “Global Alliance to Eliminate Lead Paint” to achieve international goals to prevent children’s exposure to lead from paints containing lead and to minimize occupational exposures to lead paint. Its broad objective is to promote a phase-out of the manufacture and sale of paints containing lead. International Lead Poisoning Prevention Week provides an opportunity to mobilize political and social commitment for further progress.
The Ministry of Environment, Forest and Climate Change (MOEFCC), Government of India has also prohibited manufacture, trade, import as well as export of household and decorative paints containing lead or lead compounds in excess of 90 parts per million (ppm) with a notification as “Regulation on Lead contents in Household and Decorative Paints Rules, 2016’ passed in November 2016.
Health tips to prevent lead exposure-