Is the use of "Perchloroethylene" in dry cleaning, due to the harm it causes, impermissible (haram)? And does dry steam cleaning remove impurities (najāsat) according to Islamic law?

The default rule is that it is permissible to use cleaning agents, unless their harm to humans is proven, either immediately or in the long run. In such a case, their use becomes prohibited, based on the Almighty’s saying: (And do not kill yourselves) and the Prophet’s (peace be upon him) saying: (There shall be no harm nor reciprocating harm). Many scholars have held that ritual impurity (najāsa) can only be purified with water, while others, like Shaykh al-Islam Ibn Taymiyyah, are of the view that impurity can be purified with any pure liquid that removes it. Accordingly, it is permissible to wash clothes and remove impurities with steam.