The antonyms for the word "de-contaminated" can be "contaminated", "infected", "poisonous", "toxic", "unclean", and "tainted". These words make a complete contrast to the meaning of "de-contaminated" which refers to the process of removing hazardous substances, pollutants, or toxins from materials or environments to make them safe for use or habitation. The antonyms of "de-contaminated" are mostly associated with harmful substances or materials that pose a threat to human health and the environment. Therefore, it is essential to be aware of the antonyms of "de-contaminated" to understand and identify the potential risks associated with contaminated materials or environments.