こんにちは。
「危険」はいろいろな言い方ができます。
一番基本は danger かと思います。「危険な」は dangerous になります。
他には unsafe（安全でない→危険な）、hazardous（危険な、有害な）のような表現もあります。
【例】
Walking alone in that park at night can be dangerous.
「あの公園で夜に一人で歩くのは危険なこともある」
The city was named the most unsafe city in the world.
「この街は、世界で一番危険な街に選ばれた」
ぜひ参考にしてください。
Don't go to the ghetto because it is a very bad and unsafe area.
It's too risky to go there so I wouldn't go there if I were you.
That's a pretty bad place so don't go down there.
In my area we often say "bad", "very bad", "pretty bad", "unsafe" or "ghetto" for dangerous areas.
Don't go to the ghetto because it is a very bad and unsafe area.
That area is a ghetto so don't go there.
It's too risky to go there so I wouldn't go there if I were you.
That's a pretty bad place so don't go down there.
Stay away from that area or you'll get hurt.
私の住んでいる所では、危険な場所を表すときはよく、"bad" "very bad" "pretty bad" "unsafe" "ghetto" を使います。
Don't go to the ghetto because it is a very bad and unsafe area.
（スラム街に行かないようにね、すごく危険な場所だから）
That area is a ghetto so don't go there.
（あのエリアはスラム街だから、行かない方がいい）
It's too risky to go there so I wouldn't go there if I were you.
（あそこに行くのは危険すぎる、だから私なら行かない）
That's a pretty bad place so don't go down there.
（あそこは危険な場所だから、行っちゃダメだよ）
Stay away from that area or you'll get hurt.
（あのエリアには近づかない方がいいよ、けがするよ）
Though there are many ways to say 'unsafe', the meanings are all slightly different and can be used in different contexts.
'hazardous' for example can be used in a situation when your health or safety is at risk.
1) The chemicals are hazardous if inhaled.
2) The ill-planned journey was hazardous and inevitable to fail.
'Risky' can be used when there is a possibility of something bad happening.
1) I would never travel alone because it is too risky.
2) It is risky to buy a house without any advice.
'Dangerous' can be used in a situation where an animal, person or thing could harm you.
1) His parents think rugby is dangerous.
2) The bank robbers were armed and dangerous.
unsafe'（危険な）の言い方はたくさんありますが、どれも意味は微妙に異なり、使われる文脈も同じではありません。
例えば、'hazardous' は、健康や安全性にリスクがあるときに使われます。
1) The chemicals are hazardous if inhaled.（その化学物質は吸い込むと危険です）
2) The ill-planned journey was hazardous and inevitable to fail.（その計画性に乏しい旅行は危険がいっぱいで、失敗は必至だった）
'risky' は何か悪いことが起こる可能性があるときに使えます。
1) I would never travel alone because it is too risky.（私は絶対に1人では旅をしません、リスクが大きすぎます）
2) It is risky to buy a house without any advice.（何のアドバイスも受けずに家を買うのはリスクがあります）
'dangerous' は動物・人・物から危害を受ける可能性のある場面で使われます
1) His parents think rugby is dangerous.（彼の親はラグビーが危険と思っています）
2) The bank robbers were armed and dangerous.（銀行強盗は武装していて危険でした）
If something is not safe then as well as saying it is 'unsafe' you can also use words such as 'dangerous', 'risky', 'hazardous' these all mean they are not safe and to be careful
The three words you see provided above are what we use to describe a place or area that is not safe. The word dangerous and unsafe would be appropriate for a formal setting, like talking in a business meeting or giving a presentation. The word risky would be appropriate for informal settings, like talking with close friends or family.
The most simple answer to your question is 'That place is not safe.'. However, more descriptive words add variety to your English. You could use the word 'dangerous' which means 'not safe'. In England, you could also use the word dodgy which is commonly used. This is more informal, so you would probably only say this when talking with friends.
あなたの質問に対する最もシンプルな回答は 'That place is not safe.' です。ただ、より具体的な言葉を覚えておくと表現に変化がつきます。
例えば、「危険な」という意味の 'dangerous' が使えます。
イングランドでは 'dodgy'（危ない）もよく使われます。これはインフォーマルなので、友達に対してしか使わないと思います。
When something is not safe, then you may describe it as "unsafe", "dangerous" or "extremely risky".
You may use these terms in a sentence in the following ways:
-Do not play on train tracks because it's dangerous.
-My neighborhood is unsafe because there are a lot of gang members
-It's an extremely risky investment because you could lose all your money.
安全でないものは、"unsafe" や "dangerous" "extremely risky" と表せます。
文の中では次のように使えます。
-Do not play on train tracks because it's dangerous.
（線路で遊んではダメ、危ないから）
-My neighborhood is unsafe because there are a lot of gang members
（うちの近所は暴力団員が多いので安全ではありません）
-It's an extremely risky investment because you could lose all your money.
（これはすごくリスクのある投資です、全財産を失う可能性もあります）
The opposite of 'safe' is 'unsafe' or 'dangerous', and in practice, there seems to be little difference between these two adjectives.
'It is unsafe to play football without a gumshield - you could loose all your teeth!"
safe' の反意語は 'unsafe' または 'dangerous' です。この二つの形容詞にはほとんど違いはないと思います。
'It is unsafe to play football without a gumshield - you could lose all your teeth!'
（マウスピースをはめずにフットボールをするのは危険です、歯が全部取れる可能性もあります）
「危険な」という意味の英語には dangerous や unsafe, hazardous などがあります。
dangerous と unsafe は幅広い「危険な」という意味を表し、
hazardous は健康や安全面での危険をはらむ、という意味になります。
The oil takers have to go through dangerous/unsafe areas.
その石油タンカーは危険な場所を通過しなければいけない。
I heard that this product may contain hazardous materials.
この製品は有害物質を含んでいるかもと聞きました。
「危険」という名詞はdanger
「危険な」という形容詞はdangerousと言います(*^_^*)
「危険な地域」と言いたい場合は、an dangerous areaと言います(*^_^*)
例）
It is dangerous to walk alone around here.
「この辺りを1人で歩くのは危険だ」
以上です。
少しでも参考になれば幸いです(*^_^*)
There are many synonyms to describe something that is unsafe. If something is 'risky' or 'high risk' it means there is an element of danger involved and this should be evaluated before deciding whether you will continue.
If we describe something as 'threatening' it means that there are many risks involved.
To be in danger or at risk, means you are putting yourself in a dangerous or unsafe position and that you must take care in these situations. The place was dangerous. I felt in danger when I was there.
to be in danger' または 'to be at risk' は「用心が必要な危険な状況にいる」という意味です。
The place was dangerous.
（その場所は危険だった）
I felt in danger when I was there.
（そこにいるときは危険を感じた）
Don't go running down that hill.
Why not?
It is dangerous, you might hurt yourself.
Oh okay. I am still going to go though.
I hope this helps.
Have a great day.
Will
アメリカ合衆国 
イギリス 
南アフリカ 
ミャンマー 
日本 
