1. School of Public and Environmental Affairs, Indiana University, Bloomington, IN 47405, USA.
2. Citizens for a Better Environment, Milwaukee, WI 53202, USA.
3. Institute for Health and the Environment, University at Albany, Rensselaer, NY 12144, USA.
4. AXYS Analytical Services, Post Office Box 2219, 2045 Mills Road, Sidney, British Columbia, Canada V8L 3S8.
5. Department of Natural Resources, Cornell University, Ithaca, NY 14853, USA.