I posted this same question in Dec '03 in this same forum ( you can check it out if you want). Didn't get a conclusive answer ( if anyone really knows for sure). My concern was for gradual leaching of arsenic into the pond. It could then follow the food chain up to the fish and then into yourself ( similar to mercury). My concerns would be gradual poisoning from accumulation over a period of time. Chronic toxicity can result in various cancers, skin ailments, GI and nervous system problems. My two cents would be to find an alternative.
Sarc
