Feature

Stripped - the story of lead in paint in South Africa

Angela Mathee and Brendan Barnes

Puzzled by the lead poisoning of a single child, MRC researchers didn't stop until they discovered its source: the lead used in paint. And the legislation they have since lobbied for could help millions of children. 

Some of the most important health hazards of our time were identified from just a single case.

In 1978, Kenneth Feldman, a paediatrician in the United States, treated a 32-month-old child for scald burns. The child sustained the injury when she was put into a hot bath feet first.

Feldman identified 57 such cases from hospital records, visited each child's home and measured the water temperature at the tap. He found that the water temperature set by manufacturers was 65°C, which was far too hot for children's sensitive skin.

Not satisfied with accepting this as an interesting scientific finding, Feldman successfully campaigned for legislation to reduce the hot water temperature to 49°C and thereby significantly reduced the number of US children hospitalised for scalding.

Nearly three decades later, a single case was also the key in a discovery by MRC scientists that South African children are being exposed to unacceptably high levels of lead.

Lead is a widely used, but toxic, heavy metal that can cause a number of child health problems. At relatively low exposures, statistically significant associations have been shown between children's blood lead concentrations and conditions such as mild intellectual impairment, hyperactivity, shortened concentration spans and the emergence of violent or aggressive behaviour.

At high levels, lead exposure has been associated with damage to virtually all organ systems, including the brain, heart, kidneys, liver and circulatory system.

The current internationally accepted ‘ action level' for lead is ten micrograms of lead per decilitre of blood. It is called an action level because as soon as the concentration of lead in a child's body reaches or exceeds this level, the child needs to receive medical attention.

This recommendation is far from over-cautious: negative health effects have been shown in children with blood lead levels as low as a third of that.

After a country-wide study of children's blood lead levels in 2002, MRC scientists from the Health and Development Research Group discovered a seven-year-old girl whose blood lead level was 44 micrograms per decilitre, compared to the average of 9,1 in the rest of the children they tested.

One month later, when the scientists conducted follow-up tests to verify their finding, they discovered that the child's blood lead levels had increased to 52 - over five times the international action level. The child was immediately referred to a paediatric hospital for treatment, leaving the MRC team with the task of finding the source of the child's lead poisoning.

Interviews with the child's parents revealed that she had a bad pica habit (the tendency to eat non-food items, including soil) and was frequently eating paint off the walls of her home, despite valiant attempts by her parents to stop her from doing so. Tests on paint samples taken from her home revealed lead concentrations that were nine times higher than the internationally accepted action level.

Although researchers have known since the early 1980s that South African children were exposed to high levels of lead, the source was mainly attributed to the lead added to petrol. This seemed to be confirmed when, after the introduction of unleaded petrol in 1996, MRC studies began to show associated reductions in child blood lead levels.

However, the 2002 study showed that lead was still very much present in the blood of South African children - and paint started to emerge as an important suspect in the search for its source.

Inspired by these findings, the MRC team collected paint and dust samples from the homes of the twenty children with the highest blood lead levels identified in the 2002 survey. The results showed that over one third of the paint samples and 79% of the dust samples had lead levels above the international standards.

These findings were worrying indeed, and the group of scientists next decided to examine the levels of lead in residential paint in houses across Johannesburg. Of the 239 homes they tested, 20% were found to have unacceptably high lead levels in their paint.

Considering that the South African Paint Manufacturers' Association had entered into a voluntary agreement to limit the use of lead in paint in the mid-1970s, it came as a surprise that homes built after this time had paint with high lead levels.

These findings, in turn, led the MRC team to test both popular and lesser-known brands of enamel paint currently being sold to the general public from paint stores in Cape Town and Johannesburg. The results showed that 83% of the pigmented enamel paint samples were lead-based, with lead concentrations ranging up to 38 times the international reference standard. Only one out of the eleven brands of lead-based paint they tested carried a warning label. Lead-based paint, it seemed, was still being widely sold - to mostly unsuspecting customers in South Africa.

Of particular interest to the team was where and how this paint might end up near young children.

A 2005 screening study of lead in certain children's painted toys found that some of them contained as much as 135 903 micrograms of lead per gram of paint. This was an astounding 1 500 times higher than the recommended safety level of 90 micrograms.

Painted toys with a high lead content included children's building blocks and puzzles - toys that are commonly used in homes, schools and pre-school institutions.

These alarming findings were conveyed to MRC President Prof Anthony MBewu who, in turn, presented a technical report to the Minister of Health. The Ministry immediately took steps towards legislative action to regulate the use of lead in paint, thereby replacing the current voluntary agreement.

This series of investigations and actions was inspired by one observation of a young girl who had extremely elevated blood lead levels. The team could have merely recorded her test results, elevated though they were, and been satisfied with an interesting study. However, like Feldman and many others, driven by scientific curiosity and the passion for knowledge that can make a difference, the team pursued a series of questions that led them ever closer to the truth.

Their painstaking work led not only to the discovery of paint as a major source of lead poisoning in South Africa, but also to the initiation of legislative processes and the first nationwide awareness campaign to inform the South African public about this major environmental health problem.

A hands-on response

After discovering the young girl with elevated blood lead levels and high concentrations of lead in the paint in her home, MRC researchers believed that the situation was life threatening enough to warrant immediate intervention. In consultation with the Ethics Review Committee from which ethical approval for the study had been obtained, the team made arrangements to inform the child's parents of her condition.

The child was immediately admitted to the local children's hospital where she obtained treatment for her condition, including counselling for her pica tendencies. The MRC also supported the replacement of the old paint in her home with lead-free paint.

Given the toxic nature of the existing paint, the refurbishment involved temporarily relocating the family while the paint was stripped, removed and safely disposed of by environmental professionals.

It is too soon to know whether these interventions have had an impact on the child. However, the study team is closely monitoring her condition.

More information:

  Dr Mathee angie.mathee@mrc.ac.za is the Director of the MRC Health and Development Research Group, where Mr Barnes brendon.barnes@mrc.ac.za is a senior scientist.

Article and image courtesy and © MRC News.

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