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Sources of Exposure to Lead

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Sources of occupational and environmental exposure to lead are discussed and the symptoms of lead poisoning are summarized.

Some occupations where exposure to lead is normal are:

1. Demolition. The use of an oxy-acetylene torch to cut through metal, which has been painted with lead-based paint, is a serious source of lead exposure. The vapour is breathed in and leads to high exposure.
2. Firearms. Firearms instructors spending most of their time in indoor ranges can show some exposure if ventilation is poor. Amateur firearms enthusiasts have shown high lead exposure. Apparently it is not unknown for some to lick the shot before putting it in the barrel.
3. Plumbing. Some exposure to lead pipe and solder, but generally plumbers' blood lead levels are well under control.
4. Specialist Paint Manufacture. Although lead is no longer used in normal household paints, it can be used in some specialist paints. Exposure is generally low.
5. Soldering (Electronics, Radiators). Workers in the electronics industry show only low exposure whereas it is rather more in the remanufacture of vehicle radiators.
6. Scrap metal recovery. Melting down of lead from batteries, lead pipes or lead roofing can lead to very high exposure.
7. Stained Glass. The manufacture of leaded stained glass windows can result in high blood lead levels.
8. Lead-acid Battery Manufacture

1. Water. In public water supplies, uptake of lead from lead pipes has been reduced by the addition of lime to increase the pH and phosphate to line the pipe with insoluble lead phosphate. Private water supplies can still be a problem as the water in certain parts is quite acidic. Unfortunately, even new houses can have problems with high lead levels in the water supply. The use of lead-based solder to solder joints in copper piping can, not only lead to high lead concentrations, but also high concentrations of copper and zinc from galvanic corrosion of copper pipes and brass fittings. Lead-based solder is supposed not to be used for drinking water supplies. However, recent evidence indicates that guidelines are often not being followed. The current limit of 50 µg/l of lead in water is being progressively reduced to 10 µg/l.
2. Old paint. Current household paint is lead-free, but old paint contains high levels and its removal can be hazardous. Burning off with a blow-lamp is not recommended, but a hot-air gun can be used to melt the paint. Rubbing down should be carried out with a wet waterproof abrasive paper. Paint flakes breaking away from old paint can be a hazard to young children who tend to put everything in their mouth ('pica'). The degenerating paint will result in high lead levels in the household dust, again a source of exposure for children playing.
3. Cosmetics, Ethnic Medicines. Some cosmetics used by Asian communities have been shown to have high lead concentrations and to give raised blood lead levels, especially to children. Some ethnic medicines, bought abroad or unofficially imported here, have been found to have high concentrations of lead, arsenic or mercury. Cases of lead poisoning from ethnic medicines have been reported around the UK.

Early symptoms are of fatigue, disturbed sleep and constipation. This leads to abdominal pain (colic), anaemia, kidney disease and peripheral neuropathy. In severe cases, encephalopathy results. Provided exposure does not go too far, the symptoms are reversible by removing the source of exposure. Absorbed lead is excreted in urine or is deposited in bone.