This week's programme in the series on Man and Science Today.

Each of us eats about half a ton of food a year, of which 3 lbs is likely to be chemical additives. They are included by food manufacturers to colour, flavour, preserve and improve their products. In the last year three have been banned; Ponceau MX, a colouring, brominated vegetable oil, an emulsifier, and cyclamates, which were used as sweeteners. Their withdrawal has heightened a growing uncertainty about the use of additives.
Are they necessary? Are they safe? How are we protected?
As well as trying to answer these questions the programme reveals some surprising facts about our so-called 'natural' foods.
Introduced by Christopher Chataway