There is an organization taht's certain splenda is the worst thing in the world.
but no studies have shown splenda to cause cancer, unlike sacchrine which is the sweetner you're thinking of.
sucralose is a normal sugar molecule with a chlorine ion added. That one change means the body can't process it as a sugar. so it tastes sweet but doesn't affect blood sugar or calorie intake.
Still, I would take it in moderation. Ween yourself off sweet things so you don't crave sugary snacks as much.