re: Trespasser beware

the average US Penny minted after the latter half of 1982, has a mass of 2.5 grams. 97.5% of that mass is zinc. That equals about 2.4g (2,400mg). The LD50 for zinc, or dose at which 50% of animals that have ingested zinc will die is 100mg per kg of body weight. That means, that half of the 24kg (53lb) dogs who eat one penny, will die–if not treated. This is a little smaller than an average Golden Retriever.
Penny Poison Link