What is the ruling on touching unslaughtered meat, and does the hand become impure by it? And what is the ruling on using medical materials such as ultrasound gel and medicines whose ingredient sources are unknown?

The permissibility of eating the meat of the Ahl al-Kitāb (People of the Book) is conditional upon their slaughter being in accordance with Islamic law. If it is established that they stun, bludgeon, or suffocate the animal until it dies, then it is not permissible to eat it. Meats that have not been slaughtered in the prescribed Islamic manner are considered carrion and impure by scholarly consensus. If any of it touches the body or clothes, it must be washed. Medicines and topical gels are, in principle, pure, and there is no harm in using them unless there is a reason to suspect the ingredients they contain.