BOSTON — Ice isn’t always nice.
Tests of 156 bags of ice sold in grocery stores, liquor stores and gas stations across Southern California found that 19 percent exceeded recommended thresholds for bacterial contamination. Researchers also found that 56 percent had detectable levels of mold or yeast. The research was presented June 17 at Microbe 2016, a joint meeting of the American Society for Microbiology and Interscience Conference on Antimicrobial Agents and Chemotherapy.
About 2 billion bags of ice are sold every year, according to the International Packaged Ice Association, which sponsored the research. IPIA sets ice handling standards, including requiring that ice have fewer than 500 microbial colonies per milliliter of thawed ice.
The greatest contamination occurred in a sample that contained 24,000 colonies per milliliter, according to Justin Lee, a master’s degree student at Cal Poly Pomona in California, who presented the research. None of the ice adhering to IPIA requirements exceeded acceptable levels of microbes. About 500 of approximately 700 North American companies that sell ice follow IPIA practices and put the IPIA seal on their product.