I read on the packets of lead sinkers i had purchased last week that it says it is harmful to the water you fish, i was curious about this so i dropped one into a goldfish bowl with 4 goldfish in it and in 1 day, all the fish had died. i tried again but with no sinker and the fish are still alive here on my shelf. As you know, almost all fishermen use lead sinkers and many of them lose alot when fishing (e.g. snags, fish breaking line, etc.) and one day, when the number of sinkers in the lake/pond get too high, the fish will start to die. so think of that the next time you use lead sinkers.