Something that is cancer-causing is carcinogenic.
A carcinogen is an agent that causes cancer.
A teratogen is an agent that causes birth defects.
Carcinogen
pathogenAn agent of infection is a pathogen.
Pollution and pestitides and viruses. The word for a sunstance that causes cancer is carcinogenic.
A cytotoxin is an agent that kills cells
In medical terms, an agent usually refers to a medication. For instance, an antihypertensive agent reduces blood pressure.
Anesthesia: Partial or complete loss of sensation, with or without loss of consciousness, as a result of disease, injury, or administration of an anesthetic agent, usually by injection or inhalation.
That which disinfects; an agent for removing the causes of infection, as chlorine.
An antimotility agent controls loose stools.
nonpathogen
An antineoplastic agent is one that works against tumors. A tumor is also known in medical terms as a neoplasm.