Ototoxic substances are chemicals or drugs that can cause damage to the structures of the inner ear, leading to hearing loss or balance disorders. These substances can be found in a variety of settings, including industrial environments, medical treatments, and even household products. Common ototoxic agents include certain antibiotics, chemotherapy drugs, solvents, and heavy metals like lead and mercury. The effects of these substances can be temporary or permanent, depending on the level and duration of exposure.