In order to get onto the European list of permitted additives (to become an E number), a chemical has to undergo a number of toxicological tests. So it’s very unlikely that an additive will actually poison you. Mass poisonings in the past have usually been due to chemicals which got into the food chain accidentally, not by design. That doesn’t mean the chemicals used as additives don't have any toxic effects – you’re just not going to consume them in anything like the doses needed for toxicity to show. However, there are some scientific mechanisms by which food additives, or their metabolic products, could cause sub-clinical effects.

Did you know … ?
Some kinds of bacon contain nitrite which can interfere with the red blood cells’ ability to carry oxygen.

Doses
Whether it’s cyanide, dodgy mushrooms or food additives, the same toxicological principles hold true. If a chemical has any toxicity, the extent to which it shows depends on several factors. Firstly, you have to consume the chemical in high enough doses to cause damage (a single molecule of cyanide never did anyone any harm). Then there’s the length of time you consume it over (six cans of fizzy pop in one sitting could be trouble). There are differences due to age, sex and species (just because something’s safe for laboratory rats, it may not be safe for humans). And finally there can be environmental effects, which may aggravate or mitigate toxicity.

Did you know … ?
Even water can be toxic if you drink enough of it.

Scientific mechanisms of toxicity
It’s a myth that all chemicals are toxic – in fact many pass straight through you without any ill effects. But when known poisons do work their evil ways, they do so through several distinct biological mechanisms. Some poisons stop ions like calcium from getting in and out of cells. Others interfere with our ability to get energy from food. Others compete with the chemicals our bodies need, like oxygen. Yet others deactivate the proteins and nucleic acids that are crucial to the day-to-day running of our bodies. And if it’s DNA they happen to attack, they could cause cancer.

Did you know …?
Food additives in Europe must adhere to twenty EC directives.