In a tearful interview with Channel 10 on Sunday night, the 21-year-old said that the positive test result may have been a product of cross-contamination from those around her, reports Xinhua news agency.
"I had a lot of people come forward and tell me that they took this drug. Just general people who go to the gym. Some people were using it as recovery," Jack said.
"There's the chance of it being in a contaminated supplement. The only unfortunate thing is I actually hadn't taken supplements in the two months prior to that test," she added.
As a result of the positive test, Jack missed the 2019 World Championships in South Korea, although at the time the reason for her absence was not public.
Those world titles were marred by controversy when a number of competitors protested the participation of Chinese swimming champion Sun Yang, who was accused of breaching anti-doping rules by not cooperating with officials.
Jack is expecting to be formally charged by the Australian Sports Anti-Doping Authority (ASADA) before the end of the year and faces a four-year ban if unable to prove her innocence.
One option for defence which Jack cited during the interview is known as the cocaine kiss. It refers to a case involving Canadian pole-vaulter Shawn Barber, who avoided a ban despite a positive cocaine test by claiming he ingested the drug via kissing in 2016.
( With inputs from IANS )