Toxic Waste is a brand of "hazardously sour" hard candy known for its intense sour flavor that fades to a sweet center. Available in various fruity flavors like apple, watermelon, and blue raspberry, the candy comes in a distinctive drum-shaped container and is often the subject of social media challenges to see how long people can keep it in their mouth. The brand includes other sour products, and some specific products, like the Nuclear Sludge Chew Bars, have been recalled in the past due to lead contamination. 

Yes, Toxic Waste is widely considered the sourest candy in the world, often topping lists and challenges for its extremely sour, double-action sourness. While there is no single, definitive answer due to taste-testing limitations, it is a strong contender for the title due to its high level of acidity and reputation among consumers and candy experts.