Lead exposure continues to be a public health burden across the world because of its severe effects on people, and in particular, children. High levels of lead exposure affects the brain and central nervous system and can cause convulsions, coma and even death. Children who survive lead poisoning may be left with mental and behavioural disorders.
Lower levels of lead exposure are also harmful and can affect brain development and result in behavioural changes, anaemia, hypertension, renal impairment, immune-toxicity and toxicity to the reproductive organs. According to the World Health Organization (WHO), the neurological and behavioural effects of lead are believed to be irreversible. Ecological and epidemiological studies in developed nations have further linked lead exposure to antisocial and criminal activities in adolescents and adults.
Based on 2016 data, the Institute for Health Metrics and Evaluation (IHME) has estimated that lead exposure accounted for 540 000 deaths and 13.9 million years lost to disability and death (disability-adjusted life years (DALYs)) worldwide due to the long term effects on health. IHME also found that lead exposure accounted for 63.8% of the global burden of idiopathic developmental intellectual disability, 3% of the global burden of ischaemic heart disease and 3.1% of the global burden of stroke.
Even blood lead concentrations as low as 5 µg/dL (micrograms per decilitre) is associated with decreased intelligence in children, behavioural difficulties and learning problems.
In South Africa, children could still be exposed to lead in their school, living and playing environment, and their parents’ work environments. There is no safe known blood lead concentration and when lead exposure increases, the severity of symptoms and effects also escalates. Some of the primary sources of lead exposure and poisoning includes leaded fuel and leaded paint.
In the past decade, leaded fuel has been phased out in most countries and has resulted in a significant decline in population-level blood lead concentrations. Several studies by the International Persistent Organic Pollutants Elimination Network (IEPN) over recent years show that high levels of lead in paint still exist in more than 55 countries. The group collected and analysed more than 3,300 paints in 58 countries, which were widely sold. It found that in nine out of 12 countries, lead levels were greater than 10,000 parts per million (ppm) in 7% to 20% of paints tested. Much more needs to be done to phase out leaded paint, which is recognized as a huge problem across the world.
In South Africa, epidemiological studies reveal that while blood lead distributions in children have started to decline following the introduction of unleaded petrol, certain vulnerable groups continue to be exposed to environmental lead from multiple sources. Lead is widely used in both the formal and informal sectors. This includes cottage industries (eg.jewellery making, spray painting, welding, hair dressing, mining, lead melting in fishing communities) as well as in Ayurvedic and Chinese traditional medicines, battery recycling and the manufacture of certain products.
There has been some headway in mitigating lead exposure in South Africa following the banning of lead in home paint in 2012 but given the various other sources of lead exposure, much more needs to be done to curb lead poisoning.
We believe that it starts with manufacturers, and our appeal to them is to rethink the use of lead and rather look for alternatives. Our call to action is to create awareness across the country so that citizens can stop purchasing leaded products for their homes and offices. As the NIOH, our ultimate aim is to ensure the wellbeing of South Africa’s citizens by contributing to the mitigation of lead poisoning.
Globally, WHO is currently developing guidelines on the prevention of lead poisoning, which will provide policy-makers, public health authorities and health professionals with evidence-based guidance on the measures they can take to protect the health of children and adults from lead exposure.
Nisha Naicker is the Head of the Epidemiology and Surveillance Section of the National Institute for Occupational Health (NIOH).