とされている

The structure とされている expresses that something is considered, is regarded as, or is generally accepted as being a certain way. It conveys a widely held view, common belief, or established consensus rather than the speaker's personal opinion.

It is formed from the quotative particle と, the passive form of する (される), and ている indicating an ongoing state. Literally, it means something like "it is being made/done as ~," which naturally conveys "it is regarded as ~."

Expressing general consensus or common belief

とされている is used to report what is widely believed, accepted, or established – particularly in news, academic writing, and formal speech.

Because the information is presented as a general consensus, the source is often unspecified – it is simply "what people say" or "what is accepted."

Expressing what is said or believed (without confirming truth)

とされている can also carry a nuance of reporting something without personally vouching for its accuracy. This makes it useful when stating facts that are widely accepted but not necessarily proven.

Related forms

• とされていた (past): was considered / was regarded as

  いぜん以前はあんぜん安全とされていたが、いま今はきけん危険だとわかった分かった。

  It was previously considered safe, but now it has been found to be dangerous.

• とされています (polite): is considered (polite form)

  このちいき地域はすみやすい住みやすいとされています。

  This area is regarded as easy to live in.

とされている is more formal and objective than と思われている (is thought to be), which tends to imply personal impressions. とされている suggests an established or official view.