Lead and children: An old problem for young people

Abstract

The toxic effects of lead have been known for millennia, yet its use has been widespread throughout history and across the globe. In the UK, the common uses of lead—in petrol, paint, water pipes and food containers—have been banned for decades, resulting in a decrease in the levels of lead in the population. However, there is still a legacy of lead in our environment and its use in other countries and foreign products is not so well controlled. Unfortunately, a small proportion of children in the UK continue to be exposed to harmful levels of lead. Lead is a cumulative toxin; after inhalation or ingestion, lead is distributed via the blood to soft tissue, teeth and bones, where it can build up and remain for many years (Health Protection Agency (HPA), 2011). Lead has a range of toxic effects including, but not limited to, neurological, reproductive, renal, hepatic and gastro-intestinal toxicity, and the International Agency for Research on Cancer classified lead as a probable carcinogen after highly-exposed occupational groups showed increased risk of some cancers. Lead can cross the placenta, and maternal exposure before or during pregnancy can result in spontaneous abortion, stillbirth and low birthweight. In adults, 10–15% of ingested lead is absorbed into the blood; in infants and young children, this rises to as high as 40–50% (HPA, 2011). For children up to the age of 6 years old, exposure to lead can have longterm effects on cognitive function. Epidemiological studies in children have shown an inverse relationship between blood lead concentrations above 10μg/dl and IQ but it is recognized that lead may have detrimental effects at blood concentrations as low as 5μg/dl (Chandramouli et al, 2009) and it is assumed that there is no completely harmless level of exposure (HPA, 2011). A UK study of academic performance in young children showed a decrease in Catherine Keshishian, Environmental Public Health Scientist, Centre for Radiation, Chemical and Environmental Hazards, Health Protection Agency Eirian Thomas, Principal Health Protection Scientist, Centre for Radiation, Chemical and Environmental Hazards, Health Protection Agency Ruth Ruggles, Consultant in Communicable Disease Control, Health Protection Services, Health Protection Agency reading and writing skills, SAT scores, and an increase in hyperactivity and anti-social behaviour reported by teachers, associated with increased blood lead levels, detectable many years after exposure (Chandramouli et al, 2009). Lead poisoning in children may present with anorexia, abdominal pain, vomiting, constipation, headache, weight loss or failure to thrive. Children may also display increased irritability and reduced concentration. Anaemia may develop in more severe cases. Leadinduced encephalopathy is now rare but still seen occasionally in very severe cases of poisoning. These symptoms and signs are often not evident until blood lead concentrations are around 50μg/dL. IS T O C K P H O T O /g le nn eb o