Cancer Research UK : The chemicals in cigarette smoke build up to high levels in your body over time, and are even more dangerous when mixed together.

The chemicals in cigarette smoke build up to high levels in your body over time, and are even more dangerous when mixed together.

The chemicals in cigarette smoke can build up to dangerous levels in your body

Most of the harmful substances in tobacco smoke are found at low levels in a single cigarette. But over months and years, many of them can build up to high levels in our bodies.

This is why a smoker’s risk of cancer and other diseases increases the more cigarettes they smoke a day, and the more years they spend smoking.

Compared to non-smokers, the breath and blood of smokers can have:

twice as much cadmium,
four times as much radioactive polonium-210
ten times as much benzene
ten times as much arsenic

A major source of poisons

Due to strict regulations, we are mostly protected from exposure to the poisons in smoke in the environment.

So for most of us, a large part of our exposure to cancer-causing chemicals like benzene, formaldehyde and cadmium comes from breathing in tobacco smoke. And a few poisons, such as some nitrosamines, are unique to tobacco.

Some chemicals, such as arsenic and cadmium, are also found in some types of food but for various reasons, this is less of a problem:

Chemicals that we inhale are more problematic than those we eat, because our lungs are better than our guts at absorbing them. For example, our guts absorb about 6% of cadmium in our food, but our lungs absorb 60% of any inhaled cadmium.
Some chemicals, such as arsenic and chromium, are found in less harmful forms in food than in tobacco smoke.

Why do poisons build up?

Our cells have special cleaner proteins called ‘detoxification enzymes’ that mop up harmful chemicals and convert them into harmless ones. But the chemicals in smoke, such as cadmium, can either damage or overwhelm these cleaners. Because of this, it can take decades for your body to remove any cadmium that gets inside it.

Other chemicals such as formaldehyde, ammonia and hydrogen cyanide kill cilia, the small hairs that clean toxins from your airways.

This means that the poisons in smoke accumulate in our lungs, blood and other organs over time.

A cocktail effect

Individual chemicals in smoke can be even more dangerous when mixed together. They can interact with each other to increase our risk of cancer and other diseases even more.

For example, some chemicals in tobacco smoke can directly damage part of our DNA, including key genes that protects us against cancer. These chemicals include benzo(a)pyrene, polonium-210, benzene, acrolein and nitrosamines.

This is already bad news, but it’s made worse by other chemicals. Chromium makes poisons like benzo(a)pyrene stick more strongly to DNA increasing the chances of serious damage.

Arsenic, cadmium and nickel interfere with our bodies’ defence systems and prevent them from repairing damaged DNA. This makes it even more likely that damaged cells will eventually turn cancerous.