Hyperactivity is a behaviour which causes increased movement, impulsiveness and inattention, and can interfere with learning; in its more severe form, Attention Deficit Hyperactivity Disorder (ADHD), is believed to affect between 2.4% and 5% of the population.

Scientists at Southampton University say developmental damage from seven food additives equates to that of elevated lead levels on children's IQ.

The researchers led by Professor Jim Stevenson conducted a study in order to test whether artificial food colour and additives (AFCA) affected children's behaviour.

The study involved 153 three year old children and 144 eight to nine year old children.

The children were either given a drink containing sodium benzoate and one of two AFCA mixes or a placebo mix.

Teachers and parents observed their behaviour and gave a rating and for the older group a computerised test of attention was used.

The researchers found that artificial colours or a sodium benzoate preservative (or both) in the diet resulted in increased hyperactivity in both groups of children when compared to the placebo.

The research team say that the colours had no nutritional value but the role of sodium benzoate needs further investigation.

The research has highlighted the links between artificial colourings and hyperactive behaviour and has prompted the British Food Standards Agency to call for six artificial colourings to be removed from food and drink made in Britain by the end of next year.

The Agency is considering the recommendation that manufacturers voluntarily remove six of the food additives from their products, tartrazine, quinoline yellow, sunset yellow, carmoisine, ponceau, and allura red.

The Southampton study was published in the Lancet last October.

There are a number of factors that may play a role in reducing the incidence of kidney cancer and death rates from the disease.

Dietary factors might also play some role says Professor Levi. Although their influence on kidney cancer remains unclear, some studies have shown that people who eat a diet rich in vegetables and fruit are less likely to develop the disease.

Other factors could include reduced exposure to occupational carcinogens, although the risk of such carcinogens on kidney cancer remains unclear.

The authors say that there may also be a link with better control of high blood pressure, a known risk factor for the disease, and better control of urinary tract infections.

The current study quantifies recent reductions in kidney cancer deaths and, to a lesser degree, the incidence of the disease concludes Professor Levi.

But apart from the role played by reduced tobacco smoking in men, interpretation of these trends remains open to discussion.

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