Toxic truth: Why research on lead pollution in India needs to be strengthened
The radiotoxic nature of lead is seldom addressed when the issue of toxicity of lead is discussed
Alok Srivastava, Tarak Srivastava
Published:17th Dec, 2024 at 3:57 PM
Nearly one million people die of lead poisoning every year, according to an estimate by the World Health Organization. The United Nations Children Emergency Fund (UNICEF) has projected that close to 800 million children will end up with permanent intellectual disabilities and behavioral disorders due to its toxic effects.
Humans have known to use lead for about 8,000 years, with the oldest known artifact of lead, a statuette in the temple of Osiris (Egyptian God of Fertility) located in Abydos, Egypt, believed to be 6,000 years old. The Egyptians were not aware of the toxicity of lead and would use it as an eye cosmetic with the belief that it protects them from eye diseases.
The toxicity of lead was first recorded about 4,000 years ago but its toxic symptoms on the human body including anaemia and colic were first brought to public notice by the Greek philosopher Nikander of Colophon around 2,000 years back.
Lead is a chemical toxicant but many a time it is referred to as a xenobiotic toxicant i.e. a chemical substance which is present within an organism though not required by it for its existence. It is known to promote production of reactive oxygen species which are known to cause damage to DNA, RNA and proteins within healthy cells.
Lead is also found to inhibit the absorption of iron, zinc and calcium which are essential for the healthy growth of the brain and body — especially those of growing children, thereby acting as a neurotoxicant too.
Children can be exposed to lead in two ways mainly: By coming into contact with high amounts at once (acute exposure) or by being around small amounts over a long time (chronic exposure).
They can get lead into their bodies by eating or swallowing things like leaded paint chips, dust, contaminated water, soil, toys or household items that contain lead. They can also breathe in lead dust or fumes, especially if they live in areas with industrial pollution.
Also read:"Children are affected by lead poisoning"
Acute lead poisoning in children can cause severe stomach pain, vomiting, constipation, and loss of appetite. Some children may also develop anemia, become very irritable or tired, have trouble keeping their balance, experience seizures, or even go into a coma. In rare cases, lead poisoning can cause kidney failure.
However, it is more common for children to be exposed to low levels of lead over a long time, which can have serious effects on their brain and development. This chronic exposure can lead to lower intelligence quotient, trouble paying attention, learning difficulties and memory problems.
It can also cause behavioural issues like attention deficit hyperactivity disorder, conduct disorders and difficulty with language and speech. Some children may experience stunted growth, delayed puberty, anemia and even high blood pressure due to chronic lead exposure.
Leaded petrol was once considered the most important and widespread source of lead exposure. With countries banning lead in petrol — United States in 1975, India in 2000 and the last country, Algeria, in 2021, it was thought that lead poisoning would become a thing of the past.
Unfortunately, that turned out to be untrue since lead is still found everywhere around us — in adulterated turmeric, adulterated paint used in homes and playgrounds, adulterated cosmetics like kajal and sindoor, some traditional medicines, glazes on ceramic pottery, cheap aluminum cookware, solder used in water pipes, contaminated soil, air and water around coal and lead mining sites, informal used lead acid battery recycling sites and others.
Also read:Lead in turmeric more than 200 times the limit in parts of India: Study
Chemically speaking, lead is a very interesting element as its stable isotopes have both primordial (existing since the earth came into being) as well as radiogenic (continuous formation due to decay of radioisotopic precursors) origins. By the time one finishes reading the present article many new lead atoms would have been produced on Earth, an aspect which needs to be kept in mind when discussing its toxicity.
The radiotoxic nature of lead is seldom addressed when the issue of toxicity of lead is discussed. Lead is produced through decay of radioactive members of the natural decay series of the radioisotopes of uranium, namely U-235 and U-238, and Th-232. This gives rise to several daughter radioisotopes, including Pb-210, Pb-211, Pb-212 and Pb-214.
Ionising radiation emanating from the lead radioisotopes and their radioactive precursors could also lead to DNA breakage, apoptosis, chromosomal change and gene mutation, leading to loss of normal cell and tissue homeostasis and, thereby, augmenting the chemical toxicity of lead.
The data collected from research projects carried out so far on lead pollution in India is not only scanty and sketchy but many a times based on experimental protocols which may be far from reliable.
The UNICEF report projected that nearly 275 million children out of the 800 million affected by lead pollution reside in India. That is 50 per cent of India’s child population.
It is, therefore, high time that the issue of lead toxicty is taken up in an earnest manner using standard protocols and dedicated analytical laboratory facilities, not only by government and non-government organisations but also by academic and scientific institutions within the country and across the world.
Alok Srivastava, former professor, Panjab University, Chandigarh and, presently, distinguished professor and scientific advisor, Pahle India Foundation, New Delhi. Tarak Srivastava, professor, University of Missouri School of Medicine, Kansas City, United States.
Views expressed are the author’s own and don’t necessarily reflect those of Down To Earth.
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