Is it safe to eat raspberries growing near railroad ties?

We have a patch of raspberries growing at the base of a 6-7 foot hill. At the top of the hill is a stack of 4-6 old railroad ties. The bushes are growing at least 3-4 feet away from the ties. I'm concerned that the bushes are at the base of the hill. The ties are fairly old, we have lived here fo 10 years and they looked old and weathered then. I do not smell any odors coming from the ties. There is also no visable coating on the ties.