The antonyms for the phrase 'most uninjurious' could include words such as harmful, destructive, dangerous, injurious, poisonous, lethal, and noxious. These terms imply the presence of toxins, poisons, or other harmful substances that could negatively impact people or the environment. The opposite of 'most uninjurious' would be something that is beneficial, healing, or helpful, such as a medicine or a healthy food. It is important to carefully consider the potential impacts of substances and activities in order to minimize harm and maximize positive outcomes. By choosing more safe and beneficial options, we can reduce the risk of harm and enhance our well-being.