Imagine everyday products like food, cosmetics, or even drinking water containing hidden chemicals with the potential to cause cancer. This is the unsettling reality behind nitrosamines - a group of compounds quietly forming in the things we use daily. Found in everything from processed meats to other consumer products, nitrosamines have sparked concern among scientists and regulators alike. As more is uncovered about their presence and health risks, the urgency to understand and reduce exposure to these harmful substances becomes clear.
When encountering the presence of nitrosamines in foods, one might assume that these compounds are rare or found only in trace amounts. This misconception can lead to a potential underestimation of the prevalence and effects of nitrosamines in food products.
Nitrosamines are a class of chemical compounds with the nitroso functional group (-NO) having the general formula R 2N-N=O. These compounds have raised concern due to their potential health risks mainly as they are found to be carcinogenic. Understanding how they are formed and how they manifest in food products is crucial in making educated food choices.
Nitrosamines are commonly derived from nitrites or nitric oxide under various conditions. Their occurrence has been seen in an array of products including food, pharmaceuticals, cosmetics and industrially used sources. Their contamination in water has been a challenge especially in industry as it can persist and have harmful effects.
Many nitrosamines, namely the N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA), have been identified by regulatory bodies as either potential or known human carcinogens. Concerns have been raised over these substances' possible long-term effects on human health and the environment due to their mutagenic qualities and several negative health outcomes.
Where have nitrosamines been identified?
Nitrosamines are often found as contaminants. Such compounds are common in water, soil, drinks, and drugs. Their presence can be widespread throughout the human environment.
Water: Their occurrence as contaminants in water is one not to be neglected. NDMA has often been seen in potable water which obviously due to its carcinogenic risks; rose alarm. The way it presents in water is as a result to the chloramination during the disinfection process. In addition, NDMA is the most common pollutant found in potable water.
Preserved Food: Nitrosamines can be found in a long list of products found available as food: meat, cured bacon, dry sausage, smoked fish, pickled vegetables, processed fish, cheese, soy sauce, vegetables, potatoes, oils & fats, human milk, ham, and beers.
The nitrate compounds used for preservation particularly in cured meats are influenced by a variety of factors namely: temperature, pH, processing conditions and the mixing with biogenic amines. Such factors explain why the nitrate content of processed meat products derived from different sources can be changed into nitrosamines in the stomach under the influence of the acidity of gastric secretions.
Salt: Throughout history, salt served as an important means for the preservation and storage of meat and various foods. According to research findings, cured meats and other meat products frequently exhibit measurable amounts of N-NAs due to the preservatives used. The usage of sodium nitrate (E251) contributes to this finding, as it is regularly used as an additive compound it being a preserving agent.
Preservatives: The formation of nitrosamines formation from preserving agents ingested into the body continues to raise alarm due to their harmful effects. This continues to be supported by studies that evaluate the acute and chronic effects of such preservatives in meat products which conclude to the evidence that these substances cause diseases in animal and human models mainly through their carcinogenic and genotoxic effects.
Drugs: Nitrosamines, a couple of years ago, were found in some medication too. Particularly it was found in valsartan (a common hypertensive medication) and tetracycline (a common antibiotic used for bacterial infections). Other traces were also found in some other minute drugs.
How nitrosamines occur mostly as contaminants?
The main issues with nitrosamine contamination stem from the use of contaminated or recycled solvents and printing ink in product preparation and packaging. Environmental contamination, particularly of groundwater, also significantly contributes to nitrosamine formation. Pesticides, extensively used in agriculture and easily leached into groundwater, contain nitrogen and nitrosatable compounds, leading to inevitable nitrosamine formation.
Risks and diseases
Malignancy: NDMA and NDEA are structurally known to cause cancer hence why they are classified as carcinogenic nitrosamines. These compounds cause disease metabolically in which multiple laboratory experiments served as evidence to animals being exposed to a great carcinogenic potential. Interestingly, in some epidemiology research, NDMA and NDEA was highly associated with an increased risk of pancreatic cancer. In addition NDMA was also observed to be linked to a higher incidence of different gastrointestinal cancers in humans. The carcinogenic potential of NMDA should not be underestimated, as it has been observed to cause metastatic growth in the lungs and kidneys of rodents. Experts emphasise that liver tumours in rodents represent the most critical health effect of these compounds.
Tobacco: In cigarettes we commonly find tobacco in which specific nitrosamines have been identified. NNK and NNN are among these known carcinogens which are formed when nicotine and other alkaloids are nitrosated during the curing and processing of tobacco. The main metabolite of NNK is Nnal, which is eliminated out of the body via urine. These urinary compounds have been linked to oesophageal and lung cancer.
Gastric Cancer: The elevated risk of gastric cancer associated with a substantial consumption of processed meats is often attributed to the presence of nitrates and nitrites. The infamous carcinogen NDMA plays a significant role in the progression of this cancer. Gastric cancer is a major health issue worldwide, being the fifth most frequently diagnosed cancer globally, with an estimated one million new cases each year. Due to its high mortality rate and the tendency to be diagnosed at an advanced stage, gastric cancer is the third leading cause of cancer-related deaths.
To summarise, Nitrosamines represent a significant and often underappreciated risk to public health. Their pervasive presence in everyday items - from food and water to cosmetics and pharmaceuticals - demands heightened awareness and regulatory oversight. Despite common assumptions, nitrosamines are not isolated to rare or trace occurrences; they are widespread contaminants with substantial implications for human health. Their formation, often catalysed by everyday processes such as food preservation, water treatment, and even packaging, poses a serious challenge to minimising exposure.
The carcinogenic nature of nitrosamines, particularly compounds like NDMA and NDEA, underscores the urgency of addressing their presence. These substances have been implicated in various cancers, including pancreatic, gastrointestinal, and gastric cancers, with animal studies confirming their potent carcinogenicity. Their role in tobacco products further complicates efforts to reduce their impact, as smoking continues to be a major global health issue.
Given the extensive health risks associated with nitrosamine exposure, there is a clear need for proactive measures. Stricter regulations on food preservatives, improved water treatment protocols, and increased scrutiny of pharmaceuticals are essential steps to reduce contamination. Moreover, public education on the sources and risks of nitrosamines can empower individuals to make safer choices. Collaborative efforts between scientists, regulatory bodies, and industries are vital to effectively mitigate these risks.
Ultimately, the goal is to reduce human exposure to nitrosamines to the lowest possible levels. By understanding their formation and taking steps to control their presence, we can significantly decrease the potential for adverse health outcomes and foster a safer, healthier environment for all.
Renald Blundell is a biochemist and biotechnologist with a special interest in Natural and Alternative Medicine. He is a professor at the Faculty of Medicine and Surgery, University of Malta
Daniel Vella is currently a medical student at the University of Malta
Photo: AI-generated image created by Prof. Blundell