The cynical money-grubbing practices of food manufacturers are so yawn-makingly familiar these days. But maybe this one will tickle your jaded outrage glands - it does mine ... I'd like to know what you think.

A few years back, after endless scientific debate, the government's Food Standards Agency commissioned some research on five commonly used food colourings - all of them azo dyes. Everyone knew azo dyes, which are derived from tar, were nasty, some causing problems from allergic reaction to cancer. Indeed some of them (including the red dye known as Sudan 1) are already banned in a number of places.

There was also an interesting additional hypothesis that needed looking at - it was thought azo dyes, when combined with the soft drink preservative sodium benzoate, had particularly gruesome effects - causing hyperactivity in children. And since azo dyes make yellow, reds and browns in cheap sweets and cakes, and sodium benzoate appears in flavoured waters, Irn-Bru and so on, children get to combine the two quite often.

The scientists reported back to the government in 2007. They were definite - the combination induced hyperactivity in children, even those that had no previous history of the condition. They recommended immediate action.

Government dithered. There were a lot of well-connected sweet and cake manufacturers to consult with. And azo dyes are profitable, being slightly cheaper than the alternatives. But eventually a standard "voluntary phase-out" was worked out. And by the middle of last year most had begun to do so: supermarkets banned them in own-brand products, Nestle, even Swizzels Matlow (who make some of Britain's most fantastically lurid sweets - Refreshers, Rainbow drops and Love Hearts) switched production over to "natural dyes". Mars and Cadbury agreed to do so too.

So here we are, nearly at Easter 2009. How is the yolk in your Cadbury's Creme Egg so delightfully yellow? Through the addition of azo dye E110 Sunset Yellow, of course. The same goes for a whole dentists' nightmare of favourites that Cadbury sells - Dairy Milk, Turkish Delight, Rose's tins of retro family sweets (avoid the orange creme), Maynard's Wine Gums and Sports Mixture. Mars's Starburst Choozers still contain two and Mars Revels three of the "Dirty Six" colours. The Food Commission, which has just done a sweetshop survey, say that Mars and Cadbury pledged to remove these colourings by the end of last year.

Action on Additives co-ordinator Anna Glayzer said, "To make these pledges at times of high media attention and then quietly neglect to honour them is simply cynical PR opportunism. It is highly irresponsible behaviour from major multinational confectioners." Quite. Surprised? Since when did major corporations take voluntary action on safety grounds seriously?

Now I'm generally an eat, drink and don't-fuss-too-much sort. I can't be bothered to get heated at much that stupid food corporations do for profit, unless it involves cruelty to humans and animals (unfortunately it does, more than you might think). But I have a sweet-obsessed, allergy-prone asthmatic 4-year-old, and I am pretty sure that the fact that some sweets make her face come up like a raspberry while others don't is an additives issue. Angry with Cadbury? You bet.