LEAD POISONING

Presented by:

Group-A

Ashmita Thapa (08)

Nirmala Bista(21)

Samjhana Shrestha(29)

Seema Giri (30)

INTRODUCTIONLead soft, malleable poor metal, one of the heavy ones.low melting point & is easily moulded and shaped, and can be combined with other metals to form alloysUsed in products as diverse as pipes; storage batteries; pigments and paints; glazes; vinyl products; weights, shot and ammunition; cable covers; and radiation shielding. Once Pb is mined, processed, and introduced into the

environment, it is a potential problem forever. There is no technology that will destroy lead or render it

permanently harmless.

Nearly all of the Pb in the environment is due to man's activities

Sources of Lead Natural Source

Lead ores comprise 0.002% (15g/t) of the earth’s crust; Include galena (lead sulfide), anglesite (lead sulfate), cerussite (lead carbonate), mimetite (lead chloroarsenate) and pyromorphite (lead chlorophosphate).

Artificial Source Inorganic lead: form of lead found in old paint, soil,

dust and various consumer products Organic lead: Tetra-ethyl lead is the form of lead

used in leaded gasoline; extremely dangerous as they are absorbed through the skin and are highly toxic to the brain and central nervous system; used extensively from the 1930s to the 1970s as a petrol additive to improve engine performance.

Contd.. Tetra-ethyl lead has been eliminated from the petrol

supplies of the majority of countries including Nepal, but is still used in about 9 countries.

In1935, European countries had banned the use of lead in household paints, while the United States did so in 1971. However, this hasn’t been conducted in developing countries like Nepal.

Sources of lead

Lead Poisoning Lead poisoning is a medical condition caused by

increased levels of the heavy metal lead in the body Characterized by abdominal pain, confusion,

headache, anemia, irritability, and in severe cases ,seizures, coma, and death.

Generally occurs among children, old people and pregnant women including industrial workers in lead related occupations

Major sources of human exposure to lead are: lead added to petrol lead from an active industry, such as mining

(especially in soils)

Contd.. lead-based paints and pigments lead solder in food cans ceramic glazes drinking-water systems with lead solder and lead pipes lead in products, such as herbal and traditional

medicines, folk remedies, cosmetics and toys lead released by incineration of lead-containing waste lead in electronic waste (e-waste) lead in the food chain, via contaminated soil lead contamination as a legacy of historical

contamination from former industrial sites.

Global Status

WHO has recognized lead as a prime toxic and it does not have any biological significance

Lead poisoning accounts for about 0.6% of the global burden of disease.

impacts over 40 million children worldwide, over 97 per cent of whom live in developing countries.

20th leading cause of the global burden of diseases and ranked 16th in terms of disability adjusted life years.

Lead exposure pathway Consists of the following components: (a) a source of contamination (such as deteriorating

lead-based paint on the walls, doors and windows of a home; used car batteries; open burning of waste);

(b) an environmental medium and transport mechanism (such as lead contaminated dust on the floor of a home, lead smoke from open burning, or lead exhaust from leaded gasoline);

(c) a point of exposure (such as children’s hands, the floor, or children’s toys);

(d) a route of exposure (such as eating the dust through hand-to-mouth behaviour);

Contd…(e) an exposed population (such as children in the home

environment or pregnant women in polluted environments or workplaces).

When all five components are present, the exposure pathway is termed a complete exposure pathway.

Exposure to lead occurs mainly through Inhalation of dust and air, especially for workers in

lead-related occupations; Almost all inhaled lead is absorbed into the body i.e. 20-70%; children absorb more than adults.

Ingestion of foodstuffs, water and dust through hand-to-mouth contacts or through contaminated food, water or alcohol (in case of children)

Contd.. Dermal contact: significant for people working with

organic lead compounds, but is of little concern for general population;skin absorption rate is low for inorganic lead

The lead thus stored may be released into the bloodstream, especially in times of calcium stress (e.g., pregnancy, lactation, osteoporosis), or calcium deficiency, and is of particular risk to the developing fetus.

Health Effects Lead interferes with a variety of body processes and is

a multi-organ system toxicant that can cause neurological, cardiovascular, renal, gastrointestinal, haematological and reproductive effects.

In children, lead causes: Headaches Irritability Abdominal pain Vomiting Anemia Weight loss Poor attention span Noticeable hearing difficulty

Contd.. Slow speech development, Hyperactivity, Stunted growth, Degeneration of tissues in the central nervous system, Damage to the circulatory system, reproductive

system and gastro-intestinal system etc. Poor cognitive and behavioral development

Lead Exposure in children

Contd… In pregnant women, high levels of exposure to lead

may cause miscarriage. Chronic, high-level exposure in men can damage the

organs responsible for sperm production.

Causes small increases in blood pressure, particularly in middle-aged and old people and can cause anemia. Exposure to high lead levels can severely damage the brain and kidneys in adults or children and ultimately cause death.

Although the health based guideline for lead in drinking water is 0.1 milligrams per litre (WHO, 1993), WHO has now accepted that there is ‘no safe blood lead level’ in humans.

 

Preventive Measures

Lead poisoning is preventable. The best way to prevent it is to prevent exposure to lead.

Prevention strategies can be divided into:

individual (measures taken by a family), preventive medicine (identifying and intervening with

high-risk individuals), public health (reducing risk on a population level)

Individual level strategies Increasing their frequency of hand washing and their

intake of calcium and iron Discouraging them from putting their hands to their

mouths, Vacuuming frequently Eliminating the presence of lead-containing objects

such as blinds and jwellery in the houses. Lead pipes or plumbing solder, are to be replaced. Running water in the morning to flush out the most

contaminated water, or adjusting the water's chemistry to prevent corrosion of pipes

Use only cold water from the tap for drinking, cooking, and for making baby formula as hot water is more likely than cold water to contain higher amounts of lead.

Use of lead-free paint in homes

Preventive Medicine Strategies

It includes screening of children for blood levels and referral for medical care as necessary.

Public Health Strategies

Surveillance of potentially exposed population groups, especially the vulnerable ones (small children, pregnant women, workers).

Enforcement of occupational health standards. Environmental standards that remove lead from

petrol/gasoline, paint and plumbing

References:

http://www.cdc.gov/nceh/lead/tips.html http://www.epa.gov/opptintr/lead/index.html http://en.wikipedia.org/wiki/Lead_poisoning Childhood Lead Poisoning, WHO, 2011