1. CMES, Lab. of Environmental Toxicology, Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577, Japan
2. CMES, Lab. of Environmental Chemistry, Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577, Japan
3. Department of Equine and Small Animal Medicine, University of Helsinki, P.O. Box 57, Koetilantie 2, Helsinki FI-00014, Finland