How does lead harm health?

2009-09-02 15:48

Beijing - China has begun shutting down lead smelters for environmental checks after hundreds of children tested for high levels of lead in two separate cases this month.

Below are some facts on lead and its impact on human health:

Q: How does it hard human health?

A: Lead is a metal with no known biological benefit to humans. Too much can damage various systems of the body including the nervous and reproductive systems and the kidneys, and it can cause high blood pressure and anaemia.

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 foetuses and young children and to pregnant women.

Lead interferes with the metabolism of calcium and Vitamin D. High blood lead levels in children can cause consequences which may be irreversible including learning disabilities, behaviour problems and mental retardation. At very high levels, lead can cause convulsions, coma and death.

Q: How much is too much?

A: - Even a blood level of 10 micrograms per decilitre can have harmful effects on children's learning and behaviour.

- About 250 000 children in the United States aged five and below have blood lead levels that are higher than that limit.

Q: How are people exposed to lead?

A: - People are exposed to lead through the air they breathe, water and food. People can be exposed to lead from motor vehicle exhaust of leaded gasoline, industrial sources such as smelters and lead manufacturing and recycling industries, from cottage industry uses and contaminated landfills.

Lead from natural sources is present in tap water to some extent, but analysis of both surface and ground water suggests that lead concentration is fairly low.

Other sources include use of ceramics (containing lead) for cooking, eating or drinking. In some countries, people are exposed to lead after eating food products from cans that contain lead solder in the seams.

Q: What can be done?

A: - Remove lead from petrol/gasoline, paint and plumbing

- If lead pipes cannot be removed, cold water should be flushed through in the morning before drinking

- Surveillance of potentially exposed population groups

- Water treatment

- Removing lead solder from food cans

- Use lead-free paint in homes

- Screen children for blood lead levels over acceptable limits and referral for medical care if necessary

- The World Health Organisation says anything over 0.1 milligrams of lead per litre of drinking water is unsafe. If high levels are detected, alternative supplies or bottled water maybe necessary to protect young children.

Sources: World Health Organisation, US Centres for Disease Control and Prevention

- Reuters