Methylene chloride is a type of chemical often used as a solvent. It can dissolve other substances and is commonly found in paint strippers and industrial cleaning products. Full definition
Even if you trust Truvia and PureVia (which we don't), they are often put into drinks and snacks that are labelled «with Truvia / PureVia», which means exactly that — they «with» other sweeteners such as aspartame, sucralose (a synthetic additive created by chlorinating sugar) or Acesulfame - K, which is a potassium salt containing methylene chloride, a known carcinogen. (eluxemagazine.com)
The primary cause for concern is that Ace - K contains high levels of methylene chloride, a known carcinogen. (blog.nkdnutrition.com)