Not all carcinogens cause cancer

Too much sunlight is bad for the skin, yet it is necessary to boost the body’s vitamin D supply. — AFP

Acetaldehyde. Alcohol. Asbestos. Bitumen. Diesel exhaust particulates. Lead. Progesterone. Radon. Sunlight.

These are part of a long list of known carcinogens.

Recently, the International Agency for Research on Cancer (IARC), which is the cancer research agency of the World Health Organization (WHO), classified aspartame as a Group 2B carcinogen.

But what does this actually mean?

What are carcinogens?

A carcinogen is any substance or agent that has the potential to cause cancer.

These can be chemicals, physical agents, or biological agents that can initiate or promote the development of cancer cells.

Carcinogens can be found in various environmental, occupational and lifestyle factors.

Some common examples of carcinogens include:

> Chemical carcinogens: tobacco smoke, industrial chemicals (e.g. benzene, asbestos) and food additives.

> Physical carcinogens: Ionising radiation, such as X-rays and gamma rays, and ultraviolet (UV) radiation from the sun.

Tobacco smoke is a known carcinogen. — 123rf.com

> Biological carcinogens: Some viruses, like human papillomavirus (HPV), hepatitis B virus (HBV), and human immunodeficiency virus (HIV), can increase the risk of developing certain types of cancer.

Classification

The IARC classifies carcinogens into five groups based on the level of evidence regarding their carcinogenicity to humans.

These groups are:

> Group 1: Carcinogenic to humans

This category includes substances or exposures that have been shown to be directly linked to cancer in humans through epidemiological studies, clinical observations, or experimental data.

> Group 2A: Probably carcinogenic to humans

The link between exposure and cancer risk is supported by substantial evidence, but some uncertainties may still exist.

> Group 2B: Possibly carcinogenic to humans

This category includes agents for which there is limited evidence of their carcinogenicity in humans and higher levels of evidence in experimental animals.

The data may indicate a possible risk, but it is not sufficient to firmly establish a causal relationship.

> Group 3: Not classifiable as to its carcinogenicity to humans

This category includes agents for which there is inadequate evidence to determine whether they are carcinogenic to humans.

> Group 4: Probably not carcinogenic to humans

These substances or exposures have been thoroughly studied, and the evidence consistently shows no significant cancer risk.

Carcinogens and cancer

Cancer occurs when cells grow abnormally and uncontrollably in the body, a situation that can occur in any part of the body.

Carcinogens per se do not cause cancer at all times or in all circumstances.

These are influenced by the manner and the degree of exposure, as well as susceptibility e.g. genetic predisposition.

One example is sunlight – although it is a known carcinogen for skin cancer, nobody would advocate avoiding it completely.

The development of skin cancer depends on a combination of degree/duration of exposure to UV light as well as type of skin and genetic predisposition.

Aspartame as a carcinogen

Aspartame can be found in a wide variety of products, from diet soda to chewing gum and toothpaste.

In 1981, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) established that an acceptable daily intake for aspartame is 40mg per kilogramme of body weight.

A person weighing between 60-70kg would have to drink more than nine to 14 cans of soda daily to breach the limit.

Despite the latest classification by the IARC, JECFA has continued to recommend a similar limit for consumption.

Another recommendation is more prosaic: the WHO’s head of nutrition, Francesco Branca, was quoted as saying: “If consumers are faced with the decision of whether to take cola with sweeteners or one with sugar, I think there should be a third option considered – which is to drink water instead”.

The Wold Health Organization classified all processed meat as a carcinogen in 2015, including bacon, sausages, ham and cured meats such as prosciutto and salami. — Filepic

Other common carcinogens

Cigarettes are probably the most well-known and lethal carcinogen, killing eight million individuals every year (of which more than a million die from secondhand smoke).

Unlike most carcinogens, there is no “safe limit” for cigarettes.

Contrary to popular belief, lung cancer is not the only cancer associated with smoking. Smoking also increases the risk of developing cancers of the oesophagus, bladder, pancreas, stomach, cervix, ovary and bowels.

Processed meat is a Group 1 carcinogen because of links to increased risk of colorectal cancer.

During the processing of meat, various chemicals, such as nitrites and nitrates, are often added to enhance flavour, preserve freshness, and prolong shelf life.

When these chemicals react with certain components in the meat, they can form carcinogenic compounds called N-nitroso compounds (NOCs).

There is evidence that the compounds formed during the processing and cooking of meat can damage the cells lining the intestines, leading to the development of cancerous cells over time.

Everything in moderation

Understanding carcinogens and their potential impact on our health is crucial for cancer prevention.

However, we must be wary of overreacting and take the time to look beyond the headlines.

Staying informed about potential carcinogens and advocating for policy changes can promote a cancer-preventive environment for ourselves and future generations.

On an individual level, the best approach is not rocket science – adopting healthy lifestyle habits, such as maintaining a balanced diet, engaging in regular physical activity, managing stress, and avoiding tobacco and excessive alcohol consumption – can significantly contribute to reducing the impact of carcinogens.

Dr Helmy Haja Mydin is a consultant respiratory specialist, CEO of the Social & Economic Research Initiative and a Special Advisor to the Health Minister. For further information, email [e-mail]. The information provided is for educational and communication purposes only. The Star does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this column. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.