It's often frustrating for learners of the Japanese language when they can't express themselves clearly because they don't know a specific word. However, it can be even more frustrating when the language doesn't clearly contain the concept they're trying to get over. Case in point: the distinction between an addiction and a poison.
In Japanese, both addictions and poisonings are referred to as 中毒 ({chuudoku{), with the word before that used to define the type. So for example, here are some common phrases:

- アルコール中毒 ({arukooru chuudoku{) - alcohol addiction. Note: often shortened to アル中 ({aruchuu{), presumably because it's so common...
- 仕事中毒 ({shigoto chuudoku{) - work addiction, which although it sounds like it should be common too, is not usually shortened to {shichuu{
- インターネット中毒 ({intaanetto chuudoku{) - Internet addiction
- たばこ中毒 ({tabako chuudoku{) - nicotine addiction

- 食中毒 ({shoku chuudoku{) - food poisoning
- キノコ中毒 ({kinoko chuudoku{) - mushroom poisoning
- 鉛中毒 ({namari chuudoku{) - lead poisoning

Because no clear distinction is made between these two concepts, the dictionary often lists both for any specific word. So, for example, {チョコレート中毒{ ({chokoreeto chuudoku{) is shown as both chocolate addiction and chocolate poisoning. To the native English speaker, of course, these two are very different! If the news reported a rash of chocolate poisoning, that would be far more scary to most people than a spate of chocolate addiction, for example.
However, as a great example of Orwell's idea that language defines thinking, many Japanese people don't seem to see a clear distinction between the two concepts. That is, they (at least, the people who were asked before writing this) feel that something that you are addicted to is automatically a poison, inasmuch as the two are inseparable.