

たばこの煙は体に有害です。
この薬は大量に飲むと有害になることがあります。
子どもに有害な物質は含まれていませんか。
"ゆうがい(有害)" is in the lesson "Hospital" (Level 42), along with 11 other useful words. LinDuo has 180 topic lessons like this one, 2,379 words in total. Every word has an illustration, a transcription and pronunciation in a female and a male voice. Just 10–15 minutes a day is enough to learn them all. Free, and works offline.