A painful popcorn

To the Editor: A previously well 21-month-old boy presented with burns on his right thigh. His mother had been making popcorn in a domestic popcorn machine while holding the baby about a metre from the machine to watch it churning out the popcorn through a chute into a bowl. Soon after the corn started to pop, the baby screamed, pointing to his right thigh. The mother immediately removed his nappy and found an unpopped corn kernel lodged between the nappy and the thigh.

General examination revealed two 4 mm burns on the child's right thigh (Figure). Kenacomb cream (Bristol-Myers Squibb) was applied four times daily, and the lesions healed after five days, leaving two depigmented scars.

Burns to the right thigh caused by a popcorn maker.

Although popcorn machines are gaining increasing popularity there are few reports of injury. One report describes corneal burns in three adults caused by steam from microwave popcorn.1 We believe that this is the first reported case of paediatric injury, highlighting the potential hazards of hot-air popcorn machines.

Corn's ability to pop lies in the fact that the kernels contain a small amount of water (14% of weight) stored in a circle of soft starch inside the hard outer casing.2 When heated to about 232ºC,3 the water expands, creating pressure within, until eventually the casing gives way. The kernels explode and pop, allowing the water to escape as steam, turning the kernels inside out. It is likely that the temperature of kernels that do not pop (known to popcorn connoisseurs as "old maids")2 can reach as high as 200ºC. Because of their increased density compared with popped kernels, old maids can, as occurred in our case, be thrown further than popped kernels.

It is also worrisome that some popcorn machines are designed so that they can be used by children.4 The information booklet that accompanies the popcorn machine in this case does state "close supervision is necessary when this appliance is being used by or near children", and has a warning that as "some hot unpopped corn may be thrown from the machine during the popping process be sure to place the [machine] facing away from you or do not stand directly in front of the machine whilst it is in operation". The mother of the child in our case did not note the warning in the instruction booklet. She was not standing directly in front of the machine. Further, she was of the impression that the fluffy popped corns are not hot.

With the increased use of popcorn machines, consumers must be aware of the potential dangers of injuries, especially to young children. Our case emphasises the importance of keeping children at a safe distance while preparing hot food, including apparently harmless, fluffy popcorn.