One possible cause is glycerine: this sweet-tasting, colourless and odourless liquid is authorised as a food additive (E442) and is widely used in the production of slush ice. There is no maximum limit for glycerine, but only the amount that is technologically necessary may be used. Glycerine is often used to achieve the typical semi-frozen consistency of slush ice.
However, glycerine has the ability to lower intracranial pressure. It is therefore also used in medicine to treat elevated intracranial pressure, such as that which can occur in cases of meningitis. This effect occurs at a dose of 250 milligrams per kilogram of body weight or higher.
The European Food Safety Authority (EFSA) and the German Federal Institute for Risk Assessment (BfR) have established that young children can, by consuming less than 200 millilitres (ml) of a glycerine-containing slush ice drink can ingest enough glycerine to reach or exceed this therapeutically effective dose. Intracranial pressure that is too low can lead to symptoms such as headaches, nausea, vomiting, dizziness or double vision.
Research by the BfR has shown that slush ice can contain varying amounts of glycerine: from none at all to quite a lot. Consumers are usually unable to tell how much glycerine a slush ice actually contains. So, if you do not want to take any risks, you should either consume very little of it or avoid it altogether. In addition to glycerine, slush ice products may also contain a lot of sugar.
Further information:
- BMASGPK: Glycerine in slush ice drinks
- EFSA assessment
- BfR: Questions and answers on glycerine in slush ice