Why are heavy metals toxic?

Heavy metals are toxic because they can interfere with essential biological functions and cause damage to organs and tissues.

Heavy metals, such as lead, mercury, and cadmium, are naturally occurring elements that are present in the earth's crust. However, when they are ingested, inhaled, or absorbed by the body in excessive amounts, they can become toxic. This is because these metals have the ability to interfere with the normal functioning of the body's cells and systems.

One of the main reasons heavy metals are toxic is due to their ability to bind to proteins, which are crucial for many biological functions. When heavy metals bind to these proteins, they can alter their structure and function, leading to a range of harmful effects. For example, lead can bind to enzymes involved in the synthesis of haemoglobin, the protein that carries oxygen in our blood. This can lead to anaemia, a condition characterised by a lack of healthy red blood cells.

Heavy metals can also cause damage by generating reactive oxygen species (ROS), which are highly reactive molecules that can damage cells. This can lead to oxidative stress, a state where the body's antioxidant defenses are overwhelmed by ROS. Oxidative stress can damage DNA, proteins, and lipids, leading to a variety of diseases including cancer, cardiovascular disease, and neurodegenerative diseases.

Furthermore, heavy metals can accumulate in the body over time, particularly in the kidneys and liver, which are responsible for detoxifying the body and excreting waste. This can lead to organ damage and failure. For instance, chronic exposure to cadmium can cause kidney damage, while mercury can harm the nervous system.

In summary, heavy metals are toxic because they can interfere with essential biological functions, generate harmful reactive molecules, and accumulate in organs, causing damage and disease.