Sir, - Prof Ivan J. Perry (November 19th) does an injustice to Kellogg's Rice Krispies and similar cereals when he states that they contain a higher level of salt than sea water. The actual concentration of salt (sodium chloride) in sea water is 2.8g per 100g (references available), which is almost three times the level in Kellogg's Rice Krispies. Indeed ,the salt content of the cereal is very close to that of blood, which is 0.9g per 100g. This is not excessive in biochemical terms. - Yours, etc.,
Prof James Heffron, Analytical Biochemistry and Toxicology Laboratory, University College, Cork.