I've used sharpies for years as laundry markers and it seems to hold up
pretty well in cold water washing. My only problem using them with young
children is their horrible odor. They can make some people dizzy. You
should have plenty of ventiation if you use them with kids. Also, sharpies
dry out rather quickly because they are shellac based--you can't keep the
caps off very long.
Last summer I used some great fabric markers for t-shirt painting with kids
which have held up well. They need to be ironed to heat set the inks.
Sorry I can't remember the brand but there are lots of them out there and
they don't smell!