not just an urban legend

[lauradi7dw]

A lot of (white) teenagers in the 1970s wanted blond hair, and for many the ideal was "summer blond," the amount of lightening that one might get from being bleached by the sun. I think their may have been a chemical bleach product that was called that, so that you could get the same effect quickly, without sunning yourself. The common knowledge (rumor?) was that people who used peroxide to bleach their hair and then swam in a swimming pool ended up with green hair. Now there is Olympic swimmer
Ryan Lochte, proving it (maybe)
http://www.businessinsider.com/why-is-ryan-lochte-hair-green-2016-8?utm_source=feedburner&utm_medium=referral

Full disclosure - in the summer of 1972, I put lemon juice on my hair and spent time outdoors. The tips of my braids were blond after a while - the juice dripped down (gravity and all) instead of being evenly distributed.