Tokyo - A 36-year-old unemployed man was arrested yesterday on suspicion of poisoning a public water supply in a south-western Japanese town with defoliant. The incident comes at a time when Japan is on edge about poisonings. Last month four people were killed and 60 others fell ill after eating a curry dish tainted with arsenic and cyanide at a neighbourhood festival in Wakayama, about 450 kms west of Tokyo.