Lead poisoning associated with intellectual disabilities in children

More reasons have emerged on why there is rise in intellectual disabilities in Nigerian children. According to the latest fact sheet on Lead poisoning and health by the World Health Organisation (WHO), lead is a cumulative toxicant that affects multiple body systems and is particularly harmful to young children.

Childhood lead exposure is estimated to contribute to about 600 000 new cases of children developing intellectual disabilities every year.

Young children are particularly vulnerable to the toxic effects of lead and can suffer profound and permanent adverse health effects, particularly affecting the development of the brain and nervous system. Lead also causes long-term harm in adults, including increased risk of high blood pressure and kidney damage. Exposure of pregnant women to high levels of lead can cause miscarriage, stillbirth, premature birth and low birth weight, as well as minor malformations.

Lead has had serious consequences for the health of children. At high levels of exposure, lead attacks the brain and central nervous system to cause coma, convulsions and even death. Children who survive severe lead poisoning may be left with mental retardation and behavioural disruption. At lower levels of exposure that cause no obvious symptoms, and that previously were considered safe, lead is now known to produce a spectrum of injury across multiple body systems.

In particular lead affects children’s brain development resulting in reduced intelligence quotient (IQ), behavioural changes such as shortening of attention span and increased antisocial behaviour, and reduced educational attainment. Lead exposure also causes anaemia, hypertension, renal impairment, immune-toxicity and toxicity to the reproductive organs. The neurological and behavioural effects of lead are believed to be irreversible.

There is no known safe blood lead concentration. But it is known that, as lead exposure increases, the range and severity of symptoms and effects also increases. Even blood lead concentrations as low as 5 µg/dl, once thought to be a “safe level”, may result in decreased intelligence in children, behavioural difficulties and learning problems.

Encouragingly, the successful phasing out of leaded gasoline in most countries has resulted in a significant decline in population-level blood lead concentrations. There are now only six countries that continue to use leaded fuel.

Lead exposure is estimated to account for 143 000 deaths per year with the highest burden in developing regions.

Lead exposure is estimated to account for four per cent of the global burden of ischaemic heart disease and five per cent of the global burden of stroke.

About one-half of the burden of disease from lead occurs in the WHO South-East Asia Region, with about one-fifth each in the WHO Western Pacific and Eastern Mediterranean Regions.

Lead in the body is distributed to the brain, liver, kidney and bones. It is stored in the teeth and bones, where it accumulates over time. Human exposure is usually assessed through the measurement of lead in blood.

There is no known level of lead exposure that is considered safe but lead poisoning is entirely preventable.

Lead is a naturally occurring toxic metal found in the Earth’s crust. Its widespread use has resulted in extensive environmental contamination, human exposure and significant public health problems in many parts of the world.

Important sources of environmental contamination include mining, smelting, manufacturing and recycling activities, and, in some countries, the continued use of leaded paint and leaded gasoline.

More than three-quarters of global lead consumption is for the manufacture of lead-acid batteries for motor vehicles.

Lead is, however, also used in many other products, for example, pigments, paints, solder, stained glass, crystal vessels, ammunition, ceramic glazes, jewellery, toys and in some cosmetics and traditional medicines. Drinking water delivered through lead pipes or pipes joined with lead solder may contain lead. Much of the lead in global commerce is now obtained from recycling.