"There's not a thing that you touch on a daily basis that is not produced in some part from here in Houston," he told CNBC on Monday.
Many plants from Corpus Christi to Houston shut down or throttled back activity to prepare for Harvey.
The closure of ports and flooding mean the plants cannot get raw materials into the facilities and finished product out, Mitchell said. It remains to be seen when workers will be able to access the plants, he added.
Texas accounts for about 70 percent of U.S. production of ethylene, one of the most important chemicals used to make plastics, according to Kevin McCarthy, a partner at Vertical Research Partners who covers the global chemicals industry.
About 37 percent of total U.S. ethylene production has been disrupted since August 21, according to live monitoring by ICIS, a petrochemical market information provider.
Louisiana, which is also in the path of Harvey, is responsible for another 20 percent of U.S. ethylene output, McCarthy said.