We are not blonde so we don't dread swimming pool - When swimming in the pool, everybody's hair absorbs this copper-bearing water. Yes, the black-, brown- and red-headed kids as well as the blondies take on this still invisible dissolved metal. But only the blond-haired swimmers look like Heavy Metal groupies, since there is little pigment there to mask the green effect. And if the hair has been bleached blond you can expect near' twice the effect, as damaged or stripped hair has much more absorbency to hold the copper-bearing water. So black haired people like us...we have nothing to worry about!