Children who drink from leaking frosty mugs may be ingesting poisonous coolants that can cause blindness and even death, according to the latest issue of the Consumer Council magazine, Choice. Tests conducted in the past month found four out of seven frosty mug samples contained methanol and ethylene glycol, which are used to cool liquids without refrigeration but are poisonous. Three of the four samples crack easily, and the coolant can imperceptibly mix with the drinks, the council's vice-chairman of publicity, Dr Michael Tsui Fuk-sun, said. The four brands are Amazing, Emboss Painting, Frosty Mug and Hello Kitty. 'The mugs are like toys and are popular with children, who like to cool their drinks with them,' he said. 'Parents should be aware of the potential danger. If their children are using these mugs, they should check for cracks and leaks.' Dr Tsui said parents should watch coolant levels, and if they dropped, the mugs should be thrown away immediately. Though the amount of chemicals are below the lethal dosage for adults, Dr Tsui said children were much more vulnerable. Three of the four samples contained 2.5 millilitres to 4.51 ml of methanol. Dr Tsui said 10 ml could cause blindness in adults. The Hello Kitty mug contained 11.5 ml of ethylene glycol. The lethal dose for adults is between 60 ml and 100 ml. Dr Tsui criticised the samples for carrying misleading labels claiming the chemicals were non-toxic. 'Some say their coolant is non-toxic. Others even say the products are safe for children.'