Marion, the hairs themselves will probably not be damaged, but will pick up grease,oil, etc. which will cause a slick spot on the bow that will not hold rosin. You can completely loosen the screw and pull it out, carefully, this causes the frog to come off the bow. Swish the bow hair only in warm sudsy water, with not too much soap. I have used Woolite. Be careful not to get water on the wood or frog! Rinse the soap out, pat dry with a lint free towel, and allow to dry completely--at least overnight. It will be difficult to re rosin the bow, but have patience. When applying the new rosin, be sure to use long strokes up and down the full length of the bow.
I have heard of cleaning bow hair with kerosene, but I am afraid to try it..........