1. Department of Chemistry, Kent State University, Kent, Ohio 44242
2. Environmental Toxicology and Chemistry Laboratory, Great Lakes Center, State University of New York, College at Buffalo, Buffalo, New York 14222
3. Unidad de Matemática y Física, INFIQC, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba 5000, Argentina
4. Environmental Carcinogenesis Division, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711