two-way street

日本全国でほぼ梅雨入りしましたが、天気の良い日の陽射しは真夏を思わせるものがあります。

さて、日焼け対策していますか？


Many people love the sun.

The sun's rays make us feel good, and in the short term, it makes us look good. But our love affair isn't a two-way street.

Exposure to sun causes most of the wrinkles and age spots on our faces. A 40-year-old woman who has protected her skin from the sun actually has the skin of a 30-year-old.

We often associate a glowing complexion with good health but color obtained from tanning can mean accelerated effects of aging and an increased risk for developing skin cancer.
(Take precautions to avoid sun-caused problems. The Spectrum. June 14, 2015.)


上記の引用で、


two-way street


という表現が出てきます。何となく意味は分かりますが、このようなコンテクストで使われるのを見たのは初めてです。

one-wayは一方通行ですから、two-wayは両方向通行ということです。つまり、陽射しに当たることはいいこともあれば、悪いこともある、ということなのでしょうが、何と訳したものでしょうか。

辞書を引いてみると、


互恵的関係


という日本語が載っています。

下記のような用例では明らかでしょう。


In the case of Egypt, several diplomats and officials laud Cairo's efforts to help the US and say that it has essentially become a two-way street. Egypt is helping the US with intelligence and resources, and the US is returning Egyptian nationals wanted for committing crimes in their home country. "The level of cooperation with Egypt is up on all levels, " says a Western diplomat."
(Christian Science Monitor. 2002.)


まさしく、“互恵関係”の例です。