Lead, a soft, inexpensive metal, is considered the number one environmental poison. This toxic heavy metal and its salts have no known beneficial biological function — they have only deleterious effects. But on average, a human being utilises nearly half a tonne of lead in her lifetime — in the form of things like energy-storing lead acid batteries and shiny shirt buttons.
Unfortunately, in urban environments, near every lead-based industrial area or heavily trafficked zone, the air we breathe contains lead in particulate form. Particles measuring less than 10 microns in diameter are directly absorbed by our respiratory system. Hence, one of the main pathways of lead into humans is the inhalation of contaminated air. Inorganic lead could be ingested and directly absorbed by the digestive tract through certain foods and water, as well as some folk and unbranded traditional medicines. Apart from this, lead in its organic form could be absorbed through the skin upon application of cosmetics. Environmental lead finds its way into almost all organs of the body through these three pathways. It is important to note that there is neither a placental barrier nor a blood-brain barrier for lead. The most affected are those who work in particular industries. Though women of reproductive age are not allowed to work in lead acid battery units, they work in large numbers in the textile and electronics industries. Poorer people often have to live in areas adjoining lead-based industries, and are most vulnerable to and affected by it.
The World Health Organisation has estimated that over 120 million people are overexposed to lead, and 99 per cent of the most serious cases are in the developing world. The organisation had considered blood lead levels of less than 10 microgammes per decilitre (<10µg/dL) to be an appropriate goal. But researchers called on it to halve that level, and considered the ultimate goal of <2µg/dL to be more appropriate. A unit increase above 10µg/dL decreases a child’s IQ by 7.4 points. Lead replaces minerals, notably iron and calcium, in the body and prevents haemoglobin formation, resulting in anaemia. Even blood lead levels as low as 2µg/dL increase the risk of early death.
Even though there is wide recognition of this problem and many countries have taken action, exposure to lead, particularly in childhood, remains a key concern for healthcare providers and public health officials. Most children with lead poisoning do not show any outward symptoms unless blood lead levels are extremely high. Consequently, many cases go undiagnosed and untreated, as the symptoms include headache, stomach ache, nausea, tiredness and irritability. There is treatment for lead poisoning, but it is unaffordable to a majority of people in developing countries.
In several developing countries, there is no established recommendation for lead levels in food or blood. There is a lack of regulation and implementation of standards. Even today in India, lead content in paints manufactured for decorative purposes varies widely. Producers of traditional medicines do not display their lead content appropriately. Its presence in bottled water and children’s toys is never disclosed.
Every year, during International Lead Poisoning Awareness Week, efforts are made to raise awareness and highlight successful attempts to prevent childhood lead poisoning and urge action to eliminate lead paint.
There is a need for an urgent mass awareness campaign across the country on lead-related issues, especially at the school level. Awareness alone could prevent 60 per cent of the problem. Apart from this, all district-level hospitals must have facilities to test and monitor blood lead levels — as of now there are only 30 testing facilities in the country. We would all be smarter and live longer were it not for lead poisoning, which is entirely preventable.
The writer, professor emeritus, St John’s Medical College, Bangalore, is national chairman, Indian Society for Lead Awareness and Research.