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Lead poisoning

Sir, a 31-year-old Romanian male presented to the acute surgical unit with colicky abdominal pain for three weeks, recent loss of appetite, increasing constipation and no weight loss. He is a painter/decorator and migrated to the UK one year ago.

He was anaemic, with a normal general examination. An abdominal examination was unremarkable and chest and abdomen X-rays were normal. Blood and biochemical tests showed iron deficiency anaemia and a normal kidney and liver profile.

He was treated symptomatically with little improvement. On re-examination, he was noticed to have a bluish discolouration along his gum (Fig. 1). Further enquiry about his occupation revealed a heavy involvement in paint stripping old buildings over the past eight years. The blood film showed 'basophilic stippling' and serum lead levels were high.

Figure 1
figure1

Bluish discolouration along the patient's gum

A central nervous system examination was normal. He was treated with chelating agents with a good response.

Lead poisoning is a recognised occupational hazard. Lead containing paints are still encountered in old buildings and paint stripping presents a high exposure risk. Inhalation is the main route of exposure. Despite different legislation to control exposure, many Eastern European countries have no strict occupational health regulations. In other parts of the world, hazard from lead smelting and lead additives is a major problem for workers and consumers, for example: China and India (synthetic dye and lead paint and the 2007 Chinese export recalls). In the Middle East, tetra-ethyl lead is still added to petrol, posing an environmental risk.

Poisoning can be acute or chronic. Diagnosis can be difficult as symptoms and signs are non specific and present late until high blood lead levels are reached. Patients may present with nausea, vomiting, abdominal pain and constipation. CNS involvement can cause numbness and pain in the extremities, lethargy and mood disorders, muscle weakness, headache and memory loss. It can lead to miscarriage in women and reduced sperm count in men.

In 1840, Henry Burton described a bluish line in the gum following exposure to lead (Burton's line). Lead sulphide is produced by the reaction of lead with sulphur ions produced by oral bacteria which present as a narrow blue line alongside the edge of the gum in both upper and lower jaws. It is a reliable sign, but poor oral hygiene can produce a similar picture.

Laboratory findings of anaemia and punctuate basophilia 'basophilic stippling' is due to lead interference with haemoglobin synthesis and is not specific. Lead poisoning should be confirmed by biochemical testing of blood lead levels. An L-line X-ray fluorescence technique can measure cortical bone lead content.

Treatment includes preventing further exposure. Protective masks and clothing are important precautions as well as recognising jobs with high risk. Removal of lead from the body using chelating agents is the most important treatment. It is a slow process and requires monitoring of lead levels. Ethylenediaminetetraacetic acid can be given intravenously, sometimes combined with Dimercaprol (BAL). Edentate calcium disodium (EDTA calcium) and D-penicillamin are other useful agents.

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Khalil, A. Lead poisoning. Br Dent J 206, 608 (2009). https://doi.org/10.1038/sj.bdj.2009.524

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