People in areas affected by hurricanes Harvey and Irma should be alert to the possibility of bacterial contamination of crops from flood waters, former Environmental Protection Agency official Stan Meiburg warned on Thursday.
"The risks involved differ somewhat from area to area," said Meiburg.
In Texas, for example, there have been concerns about contamination of rice crops, as well as concerns about livestock, he told CNBC's "Power Lunch."
In Florida, there was a significant amount of destruction of the winter vegetable crops, as well as citrus and sugar cane.
"The main concerns there have been to make sure that you avoid contamination, and particularly, avoid contact [with] ... food that has been in contact with flood waters," Meiburg said.
The Food and Drug Administration said the storms have caused a "substantial" loss of crops, which may be submerged in flood water, exposed to contaminants or susceptible to mold.
"Some of the major concerns for crop safety are heavy metals, chemical, bacterial, and mold contamination. In many cases, it is challenging to determine what contaminants are in crops that were submerged by floodwaters," FDA Commissioner Scott Gottlieb wrote in a statement last week.
Food processing is also being threatened by loss of electricity, leaking ammonia from cooling systems, and contaminated surfaces, Meiburg said.
"If you lose power in food processing plants, you lose some of the ability to handle the food safety, whether in refrigeration or other parts of the process," he said.
He said plants will have to be properly cleaned and sanitized before they are used again for food processing and that there must be an adequate supply of clean water.
— Reuters contributed to this report.