Everything gives you cancer 

If even broccoli and strawberries have been linked to the dreaded disease, what hope do we have, asks Tim Dowling. 
 

I wouldn't say I've courted cancer exactly, but I have hitherto been pretty heedless of the warnings. Now, however, I have reached a stage in life where I think it may be time I stopped meeting cancer halfway. Fresh from a three-week holiday that combined lashings of alcohol, lashings of stress, plenty of sun, a good deal of red meat, a lot of passive smoking and a certain amount of aggressive smoking, I think perhaps I should try to be a little less helpful to cancer. At the very least I could avoid known carcinogens, even if for just one day. I resolved to give it a try.

My first mistake came shortly after waking up. Toothpaste, I have discovered, has several compounds (fluoride among them) that are at least suspected carcinogens, as do soap and shampoo. Breakfast, the most important meal of the day, is also a cocktail of cancer-causing substances. Heterocyclic amines - possibly carcinogenic - are created by cooking or burning foods, and are commonly found in coffee and toast.

Aflatoxins, produced by naturally occurring fungi, are found in small concentrations in milk and cereal. Aflatoxin B1, the most deadly of all the aflatoxins, has been shown to cause cancer in mice, rats, hamsters, rainbow trout, ducks, marmosets (this is a partial list, by the way), tree shrews, guinea pigs and monkeys. 

It quickly becomes clear that total carcinogenic abstention is more difficult than it sounds. Going out in the midday sun presents an obvious risk, but thanks to the radon seeping into your home from the soil below, so does staying indoors. Taking to the air is no better: high-altitude flights routinely expose passengers and crew to radiation, and the free peanuts, with their traces of carcinogenic fungal toxic metabolites, aren't much help either.

I decided to retreat to my office at the very top of the house, the furthest I can get from cancer without getting cancer, where I read up on the 15 known carcinogenic substances commonly used in roofing material.

Hunger eventually drove me back to the kitchen, with an eye towards whipping up a cancer-free salad, but here again there was no escape. While the risk of getting cancer from fruit and vegetables remains small, most of that risk is said to come from naturally occurring carcinogens, generally the organic pesticides produced by the plants themselves to keep predators at bay. Broccoli, apples, onions, oranges, strawberries, lemons and mushrooms all contain acetaldehyde, a known human carcinogen. If you close your eyes you can practically taste it.

Nitrates - which can be converted by the human body into carcinogenic nitrosamine compounds - are present in such seemingly inoffensive foods as celery, lettuce, kale and rhubarb. There are carcinogens specific to tap water, basil, beer and mustard. Cancer-causing PCBs are found in varying levels in all foods.

It's well known, of course, that certain foods have anti-carcinogenic properties: organosulphur compounds, flavonoids, tannins and carotenoids have been shown to inhibit some forms of cancer. Unfortunately, these anti-carcinogens tend to be in foods that also contain carcinogens - such as broccoli, onions, strawberries and cabbage. Even while these vegetables are preventing you from getting cancer, they are giving you cancer.

Ingesting carcinogens directly is now regarded as a rather old-fashioned way of getting cancer. These days, simply being exposed to one's environment for long periods - what used to be known as standing around minding your own business - is plenty carcinogenic enough. Diesel exhaust, asbestos, the formaldehyde in ordinary home air and crystalline silica of respirable size (ie, dust) have all been listed as carcinogens.

You can get cancer from the wax on your floors, the paint on your walls and the dyes in your shirt. We are all constantly exposed to vinyl chloride, a gas emitted by PVC plastic, which is sometimes known as new-car smell. Then there is isoprene, which the US National Toxicology Program describes as "reasonably anticipated to be a human carcinogen". Isoprene is emitted by rubber products (natural and synthetic), automobiles and trees, and is commonly found in exhaled human breath. When you breathe in you get cancer; when you breathe out, you give it to someone else.

Ultimately, however, this notion that all things are carcinogenic is misleading; risks vary wildly depending on dose, length of exposure and countless other factors. Most "known carcinogens" have only been tested on animals, in huge concentrations. Some of these substances cause tumours in mice, but not in rats or hamsters. In any case, most are unavoidable.

In short, one can do little to avoid cancer apart from the obvious: most preventable cancers are caused by smoking, drinking and poor diet, which also just happen to be the major causes of dying from things other than cancer. But because luck also appears to play a big part, cancer tends to inspire more superstition than any other disease. I realise I'm running a huge risk of contracting cancer just by writing about it. I think I'll stop here.

The Guardian