THE RAPID RISE of the ice cream industry and the general use of ice cream as a food in the past few years has added another item to the public health official's responsibilities. If an epidemiologist had been tracing an epidemic a few years back, he could have practically left ice cream out of consideration. However, today it has become such a common article of diet that it should be taken into accouint in any work of this nature. The puiblic health official, if he has not already done so, will in the very near future, need to regulate its sanitary qtuality.