Scientists at Manchester Metropolitan University believe that iron deficiency, very common in numerous developing countries, makes children more susceptible to the damage done by lead pollution.
"In kids with iron deficiency, there's a tendency to absorb more iron from the gastro-intestinal tract. But some metals compete with iron for the same transport mechanism," researcher Dr Nessar Ahmed told NutraIngredients.com.
These metals include lead and manganese.
"In an environment where there are high amounts of lead, and little iron in the diet, lead will be absorbed by young children. And even low levels of lead can cause a substantial reduction in IQ," Dr Ahmed added.
The Manchester team has recently been awarded funding by the Nestle Foundation to confirm the theory in a new study recently launched in the lead pollution capital of the world, Karachi, Pakistan.
A lack of lead-free fuels combined with heavy industry and the use of make-up known as surma are thought to be responsible for dangerous levels of lead poisoning in Pakistan, which can lead to brain damage.
About 80 per cent of the country's children have blood levels of lead that are detrimental to intelligence (around 10 micrograms of lead can cause IQ levels to fall). One study found the average level of lead in the blood of Karachi children to be 38 micrograms.
At the same time, iron deficiency is common (particularly in young girls) because of poverty and poor diet.
"In the same districts, studies show that 65 per cent of children aged seven to 60 months have iron deficiency," said Dr Ahmed, principal investigator of the new study.
"If we can prove that such deficits lead to high levels of metal absorption into the bloodstream, that will be highly significant in terms of preventing growing levels of brain damage associated with polluted environments."
Dr Ahmed and colleagues from the University of Karachi have recruited 200 Pakistani children with differing levels of iron deficiency. They will test blood and hair samples for lead and manganese.
The first findings are expected next summer.
"If our hypothesis is correct, the results should reinforce the importance of not only reducing lead and manganese pollution, but also the development of national health strategies to cut childhood iron deficiency," Dr Ahmed added.
Iron deficiency with anaemia affects about 25 per cent of infants worldwide and twice as many have iron deficiency without anaemia. Many poor and minority children in the developed countries are also affected.