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Is there a relationship between high levels of lead in the environment and poverty?
It was one of those scientific inventions that had dire consequences for the world of the 20th century and today.There was a problem in the early motor car engines. They suffered from a pinging sound that made the engine shudder. A worker at General Motors invented a solution; a solution so good it was adopted world wide for all cars: put lead into the petrol. This smoothed the engine rhythm.
Of course we know now that it did a lot more than that. As the developed countries fell in love with the automobile the personal transport proliferated to unimaginable proportions and within a lifetime were clogging up the main transport arteries and choking up the air with deadly exhaust fumes. The killer was lead the same element that weakened the Roman Empire. Scientists now speculate that the early civilisation, so organised in military and civil society had reticulated water supplies to houses and communal watering spouts. The malleable metal they used for their pipes was lead. In Latin its name is plumbum a name we have adapted in the letters pb to denote the metal and in plumber, the man who works the water supply. But its effect on the body is deadly.
Dr Angela Mathee knows this all too well. As director of the Environment and Health Research Unit of the Medical Research Council of South Africa Dr Mathee has been involved in studies that have shown a high level of lead in the children of this country.
We contacted her in her offices in Johannesburg.
What triggered your studies into lead in children?
I was introduced to the problem of lead poisoning in South African children in 1991, when I assisted Dr Yasmin von Schirnding (at that time leader of the MRC lead research programme) with lead exposure surveys in Cape Town and the lead mining town of Aggeneys in the Northern Cape. The findings of those studies were alarming – they showed that in urban areas 90 to 100% of children had blood levels of 10 µg/dl (the internationally accepted action level) or higher. We now know that at levels as low as 3 µg/dl in blood, lead can cause reductions in children’s IQ scores and behaviour problems.
What methodology was used to gain information?
Every five or so years the MRC collects blood samples from first grade children in five sites around the country, for analysis of the lead content.
How does lead affect people?
Lead poisoning is associated with a range of health and social effects. High levels of lead can cause anaemia, abnormal development of nearly all organs (especially the brain). At very high concentrations, lead can cause permanent brain damage, muscular paralysis, coma and death.
In recent decades, there has been particular concern about the association between even low levels of exposure to lead and learning difficulties, as well as behaviour problems such as hyperactivity and shortened concentrations spans. There is also a growing body of research pointing to a link between lead poisoning and aggressive or violent behaviour.
You said there is a relationship between lead poisoning and poverty in children
Lead poisoning is often described as a disease of poverty – the poorer you are, the higher your blood lead level is likely to be. Our lead exposure studies here in South Africa, show that children from highly impoverished townships such as Alexandra and Westbury, have amongst the highest blood lead levels.
What effect have your studies had on government policy?
In the past few years we have seen remarkable achievements in terms of translating lead research into policy. For example, our research findings were included in a successful motivation to parliament by the Department of Minerals and Energy to phase out the use of leaded petrol. As a result, from 1 January 2006, we only have unleaded petrol available in our country.
Our MRC research also showed that lead is still being added to paint in South Africa, around three decades after this hazardous practice was stopped in many other countries, Following an instruction from the Minister of Health, draft regulations to limit the use of lead in paint were published for public comment in the Government Gazette on 4 May 2007, and we are hopeful that formal promulgation will follow shortly.
This is obviously a problem in almost every other county in the world.
Lead poisoning is often described as a global public health problem. However countries such as the USA have implemented legislation and other measures to prevent lead poisoning, and they are now reaping the benefits in terms of improved school performance and lowered levels of violent crime.
Can one yet see improvements in lead poisoning following the phase out of lead in petrol?
Unleaded petrol was first (partially) introduced in South Africa in 1996. By 2002 we started seeing a decline in children’s blood lead levels. The first MRC survey after the complete phase-out of leaded petrol (2006) will be conducted from August 2007. We hope that the findings will show significant reductions in children’s blood lead levels.
Why is lead put into paint?
To “strengthen” the paint. In other words red, lead-based paint on a roof will not fade as quickly in the sun as another paint might.
How does paint affect us?
Lead in paint is a particular concern for children who have a condition called pica – they eat non-food items such as soil or paint. Our research has shown the highest blood lead levels in children who have pica for paint.
With ageing of homes and degradation of paint, lead particles are released and collect in house dust. While crawling about, and because of their natural propensity to explore their environment through tasting, young children can ingest appreciable amounts of lead. Research in South Africa shows that children who live in homes with peeling or flaking paint have significantly higher blood lead levels than other children.
Will lead disappear as a commercial entity and health threat?
Lead continues to be used in thousands of products, such as cellular telephones and computers, but does not necessarily pose a health problem.
However, the threat of lead poisoning will not decline satisfactorily in South Africa unless we take action to remove lead-based paint from homes and schools, implement occupational hygiene measures more strictly (to ensure that less lead is transferred from workplaces into home environments), start to tackle the use of lead in home or “cottage industries,” and implement more aggressive campaigns to educate the public about the sources and health effects of lead.
What is your next challenge?
In the years to come I plan to focus more on the relationship between lead poisoning and violent crime, as well as the use of lead in adulterated traditional practices. I am also spending more time looking at the health aspects of urbanization and poor housing.
Dr Angela Mathee was recipient of the Checkers / Shoprite SABC2 Woman of the Year Award.
Dr Angela Mathee serves on a number of international expert advisory panels including Director of the World Health Organisation Collaborating Centre for Urban Health. She has had an enormous impact on translating scientific findings into policy. In the Health Category she was this year’s winner of the Shoprite / Checkers SABC2 Woman of the Year Award.
