What are they?
Nitrosamines are chemical compounds, most of which are carcinogenic. They are used in the manufacture of cosmetics, pesticides, tobacco products and in most rubber products like balloons and condoms.
How do they end up in foods?
Nitrosamines are produced when nitrites and amines combine in acidic places like the human stomach. High temperatures and frying can increase the formation of these nitrosamines. Significant levels can be found in beer, fish, non-fat dry milk and cured meats (primarily bacon and hot dogs) and cheese preserved with nitrite pickling salt.
Why are they used in foods?
Originally they were added as preservatives to prevent salmonella infection from contaminated meat. Nitrites are added to some processed foods to increase the shelf life. For example, sodium nitrate is responsible for the pink colour in bologna. They are often used to transport fish across the Pacific Ocean and added to preserve flavor and colouring. Nitrites can also be found in fertilizers which end up on our produce like potatoes and beets.
What about water?
Fertilizers used in soil also leach nitrites into our drinking water.
How much do we consume?
Studies suggest that the average daily intake from foods was approximately 1 microgram/person in 1981. Current exposure is likely much lower due to efforts in the last twenty years to reduce nitrosamine formation in foods and beverages. A National Science Academy Report estimated that smokers absorb 17 micrograms per day from cigarette smoking. Industrial exposure from working in a rubber or chemical manufacturing plant can also be quite high.
Do they cause cancer?
Nitrosamines can cause cancer in animals which suggests that they may be carcinogenic in humans. Some studies suggest an associations with gastric and oesophageal cancer.
How are they linked to Alzheimer’s disease?
Some researchers believe nitrosamines can play a part in Alzheimer's brain degeneration. Adding high fat to the diet makes things worse.
What other diseases do they play a role in?
The same experiments showed that nitrosamines in low, limited exposure can also cause diabetes, fatty liver disease and obesity. They have also been linked to Parkinson’s disease. Nitrosamines can cause DNA damage, cell death and have been associated with insulin resistance.
Anything good about nitrosamines?
A number of small studies (done with beetroot juice which is high in nitrates) suggest that nitrosamines may enhance cardio circulation. Leafy greens also have high level of nitrates and do not seem to have the same effect on our bodies as ones that are artificially added to meats.
How do I protect myself?
Look for the label sodium nitrite on preserved foods. Avoid processed foods and eat organically grown ones. Reduce your consumption of smoked meats, processed cheeses (ones that do not melt when heated) and beer. Eating vegtables which contain antioxidants (although they also contain nitrites) can decrease the negatives aspects of nitrites. On a social level, support policies to eliminate requirements for toxic preservatives and reduce the amount of fertilizers used in farming.
How much is safe?
We don’t really know. It’s suggested that higher exposures are necessary to cause cancer, but that the lifetime accumulation of smaller doses may play a role in other diseases.