What you don't know can kill you - The lingering effects of lead poisoning

Professor Gerald Lalor. Contributor

Since May, at least 400 children have died in the Nigerian state of Zamfara, and thousands of children and adults have been hospitalised in the worst case of acute lead poisoning ever reported. The tragedy came to light when visiting teams, who were checking on a vaccination programme, noted the remarkable absence of children in several villages.

At first, villagers said the children had died of malaria, but this seemed unlikely, and investigations initiated with the aid of the Blackstone Institution, Médecins Sans Frontières, the World Health Organisation, and the United States Centers for Disease Control and Prevention showed some blood lead concentrations as high as 700 millionths of a gramme per decilitre (g/dL), far above the 70g/dL which is considered a medical emergency. The highest blood lead levels observed in Jamaica have been around 200g/dL, and these children were grievously ill.

The driver for the Nigeria poisoning was the very high market price of gold. There is a lot of gold ore in Zamfara and many villagers grasped the basics of how to extract gold from the ore: the men dug up the rocks and carried them home to be powdered by agricultural grinders where these were available, otherwise by hammers, or even stones. The powder was then flushed with water, which washed away most of the residue, leaving behind small pieces of gold.

This process could provide more earnings in two hours than the subsistence farmers could make in two months. They really had struck gold, they thought. What they didn't know (and how could they?) was that the powder that they breathed in and the waste that they dumped, sometimes in sources of drinking water, contained lethal quantities of lead.

In addition to the large number of human causalities, cows, chickens and ducks have died, and the frogs are silent. The economy is reported to be in shambles. There is no farming. It is a tragedy of the first order, yet the glitter of gold seems still to make some persons willing to take further risk, and there are reports of people still engaged in illegal mining. Much of this reminds one of Jamaican experiences at Red Pond and in the Kintyre area.

In 1963, a company was established in a district named Red Pond near to Spanish Town to recover lead from used automobile batteries. This, on the face of it, requires very little knowledge, and just as in Nigeria this year, several persons quickly caught on that they could make plenty of money for themselves. They began the recovery using backyard smelters, and occasional cases of lead poisoning began to be observed, but these were not seen as indicators of a growing general problem.

But the ventures grew, and by the 1980s, the increasing number of children being hospitalised for lead poisoning struck a worrying note, and in 1988, the Ministry of Health and the Child Development Centre carried out a well-publicised study which defined the scale of the problem and led to significant improvements and promises. The company was closed, smelting was banned, though some illegal smelting continued for many years, but the residents and many persons islandwide gained a fair appreciation of the dangers of lead poisoning. Interestingly, even with the large amount of publicity, the Red Pond experience had received, no connection seemed to have been made between that and the danger to persons squatting in Kintyre, and especially the use of an abandoned lead ore beneficiation plant as a basic school.

The Kintyre Basic School

The premises that housed a mill for crushing and concentrating lead ore from the Old Hope Mine in the 1890s was converted into the Kintyre Basic School. There was no concern for decades until soil testing in the schoolyard and surrounding areas showed the presence of extremely high concentrations of lead. The overall results suggest that every child who attended that school was likely to have been lead poisoned, and some of the observed values were high enough to require immediate medical attention.

Fortunately, the intensity of poisoning was far less than that in Zamfara, and none of the Kintyre children is known to have died from lead poisoning though, in all likelihood, their exposure to lead would have produced intelligence deficits and other problems. Preventative measures have corrected the Kintyre situation, though some continuing monitoring is going to be necessary for a long time.

Common factors

Although the scale and intensity of the Nigerian poisoning is far worse than that of the Jamaican examples, there are common factors. In each case, poor persons gained a little knowledge and exploited it, mostly quite unaware of the pending calamity. It was not that the knowledge to prevent this was not available in principle, and ironically one of the world's foremost experts on the effects of lead and other heavy metals is a Nigerian, resident in the United States. In Jamaica, there were warning cases and a fair amount of knowledge about lead poisoning - some in newspaper articles, was here to warn of risk - but somehow they were not strung together.

A significant part of the explanation for this is a view that national development in science must largely await economic development rather than the firm expectation that relevant knowledge and its proper application can lead to a better economy, operating with less pain and inefficiency. Problems like lead poisoning support the need for a rethink, and this is strengthened by problems such as food security, energy costs, environmental damage, and so on, that serious enough today, will be exacerbated by climate change.

Professor Gerald Lalor is director general of the International Centre for Environmental and Nuclear Sciences, UWI, Mona. Feedback may be sent to columns@gleanerjm.com.