Authorities have said the heavy-duty cleaner was unintentionally mixed into a bag of sugar, which a worker later added into the iced tea dispenser.
The incident demonstrates the need to be diligent about food-container labeling. The county health department gives restaurants this rationale when they are cited for the problem: "Bulk ingredients such as flour, sugar and salt that have been removed from their original containers must be labeled so they are not mistaken for similar looking ingredients and chemicals."
Despite the requirement, labeling problems occur often in restaurants, said Pam Davenport a spokeswoman for the health department.
"It's one of the most cited violations that we have," she said. "If you were to look at a range of different restaurants, it's one of the top violations."
However, since labeling is considered "non-critical" it doesn't get noticed much, Davenport said. "People haven't thought too much about it until now."
A non-critical violation is one that, if not corrected, may lead to future problems in an establishment, while a critical violation poses an immediate risk to public health.
Prosecutors could decide as early as Wednesday whether to criminally charge Dickey's employees.
South Jordan police forwarded their findings Monday to Salt Lake County District Attorney Sim Gill including allegations that staff at Dickey's Barbecue discovered more than a month ago that a toxic chemical had been mixed with sugar.
Authorities have said an employee put the cleaner, not knowing what it was, in a container of sugar last month. A witness reported to investigators that a supervisor on July 5 dipped a finger in the odd-looking substance and tasted it; the supervisor then suffered chemical burns to the tongue, said South Jordan police Cpl. Sam Winkler.
Winkler said Monday there have been differing statements from many people about how exactly the chemical got into the sugar and then remained there for a month. The substance was mixed into the iced tea dispenser Aug. 10.
Harding suffered critical burns to her mouth and esophagus from drinking the tea. Her attorney has said she is improving and is regaining her ability to speak.
The cleaning product used to remove grease from fryers, contains sodium hydroxide, or lye is the active ingredient in drain cleaner.
Dickey's Barbecue Restaurants Inc. said in a statement last week that it was an isolated incident, and nothing like it had happened in the 73 years that the Dallas-based chain has operated.