Introduction
Lead is a naturally occurring heavy metal, and usually presents in very small amount in the environment. Lead and its compounds may be found in products such as batteries, lead-based paints, lead-containing ceramics, lead solder and leaded petrol. In Hong Kong , the sale and supply of leaded petrol, which is a known major source of lead, was banned from 1 April 1999 . In everyday life, lead usually does not pose a threat to our health.
Exposure Sources
- Occupational
Industries with particularly high potential exposures include: construction work involving welding, cutting, brazing or polishing on lead surfaces and application of lead solder; most smelter operations either as a trace contaminant or as a major product; secondary lead smelters where lead is recovered from batteries; and firing ranges.
- Non-occupational
Lead may be contaminated with hazardous concentrations in lead paint, cosmetics and herbal medicines. Common exposure sources of lead with very low level for general public include contaminated food and urban dust.
Health effects of lead
Lead can enter the human body by ingestion, inhalation and skin absorption. When lead is absorbed into the body in excessive amount, it is toxic to many organs and systems. For acute effect, accidentally exposure for high dose of lead may cause abdominal pain and vomiting. For chronic effects, it may lead to anaemia, joint and muscle pain, brain and kidney damage.
Children are particularly vulnerable to lead exposure. Elevated blood lead in children can also result in learning disabilities, behavioural problems and mental retardation. In pregnant women, as lead readily crosses the placenta, foetuses are also at risk.
How can one reduce the risks of exposure to lead?
- Avoid exposure to sources of lead.
- Do not allow children to chew or mouth painted surfaces of toys or furniture that may have been painted with lead-based paint.
- Clean the dust in your house regularly if it might be decorated with lead-based paint, especially when the paint is in deteriorating conditions. It is also recommended to wash children's hands and faces frequently to remove any lead dusts and soil.
- Run the tap water for a while before drinking or cooking if your home has a old water plumbing system and it has not been used for a while, for example, overnight.
- Keep all lead contaminated / contained products away from children. Some types of pigments that are used as make-up (e.g. surma or kohl) or hair colouring dye may contain lead.
Management of lead poisoning
A blood test is available to measure the amount of lead in blood. In general, the normal blood lead level should be less than 0.15 mg/L for adults, and 0.10 mg/L for children. For cases with elevated blood lead levels / clinical symptoms, further investigation & in-patient management may be required. Chelating therapy may be indicated in some cases.
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