(Substance problems) can be toxic.Logical formLearned from3 sentences. Federal governments may identify sources of deposition of toxic substances.Logical formLearned from3 sentences. Toxic substances can be in an ecosystem.Logical formLearned from3 sentences. Toxic substances may undergo an understanding.Logical formLearned from3 sentences. Toxic substances may undergo uses.Logical formLearned from3 sentences. Toxic substances may undergo an elimination.Logical formLearned from3 sentences. A (substance issue) can be toxic.Logical formLearned from3 sentences. Toxic substances may undergo a definition.Logical formLearned from3 sentences. Toxic substances may be eliminated.Logical formLearned from3 sentences. A toxic effect can be on humans.Logical formLearned from3 sentences. A toxic effect may be observed.Logical formLearned from3 sentences. Toxic substances may produce changes.Logical formLearned from3 sentences. Persistent pollutants can be toxic substances.Logical formLearned from3 sentences. Radioactive isotopes can be toxic.Logical formLearned from3 sentences. Alterations can be toxic.Logical formLearned from3 sentences.