If we believed everything that is said about carcinogens, we would hardly dare to breathe in, let alone eat food. While the world is full of carcinogens, the good news is that our bodies are designed to deal with the challenge. The risk comes with repeated exposure over time in those with a genetic predisposition. I saw this first hand when my grandmother developed lung cancer and, frustratingly, refused to give up her 20 a day habit. It has certainly alerted me to the dangers of smoking.
But when it comes to potential carcinogens in food, the links with cancer are less clear cut. To investigate the issue, researchers mainly use case control or cohort studies to follow up people over time and check who develops cancer and who stays healthy. Diets, often eaten decades in the past, are then compared to look for any differences. Neither type of study provides conclusive evidence that a particular food causes cancer, just that the variables are statistically linked. The next step of proof requires controlled studies, or research on human tissues to prove mechanisms, but these are in very short supply.
In the meantime, should we worry about the carcinogens that are reported to exist in cleaning products, pesticides, food, make-up, hair dyes and deodorants? No, because the crucial aspects for reducing cancer risks are how much exposure you have to carcinogens and over what length of time. This is why there are strict rules governing the levels of potentially carcinogenic substances that are allowed into foods and consumer products.