Ch.6 question. Please please use IRAC method

For many years, the Funch Gum company sold product that it called "Aspargum, " a low-calorie gum made from asparagus and other ingredients. Although Aspargum never enjoyed great success in the market, it did prove popular with a small number of people. Clint chewed Aspargum almost daily for nearly 15 years. Clint was diagnosed recently with mouth cancer and has sued Funch. Funch admits that three years ago it was determined that Aspargum increased the chance of getting lung cancer by 80% in those people who smoked and chewed Aspargum. Funch then put warning labels on the gum to make people aware of this risk and asked smokers not to use the product. Clint continued to use the product for the next 5 years after the warning labels were placed on the product. Funch insists Clint's cancer was due to the cigarettes he smoked over 25 years. In fact, evidence shows there is a 60% chance that it was caused by smoking. Should Funch be held liable for Clint's mouth cancer?