There's a few chemicals that can increase the risk of cancer in foods and drinks.

There's Antimony which is used in the making of P.E.T plastics (drink bottles & microwave dinner containers, for example) which can seep into the drink and foods. There's also Aspartame which is a sugar substitute which is used in drinks and sweets which is also carcinogenic. [About Aspartame]

That's all I really know about, though.