Okay, so they are saying here not so bad in adults, just maybe get copper inbalance if it isn't excreeted:
Coin Ingestion, an Unexpected Finding at Colonoscopy: Case Report
from Medscape General Medicine [TM]
Posted 02/11/2003
Matthew J. Brookes, MB, ChB, Alison M. Brind, MB
Log In Problems
"...A review of 10 years of experience with ingested foreign bodies, in 101 patients of all ages (9 months to 87 years), revealed that 46% had spontaneous passage of the foreign body. Endoscopic removal of retained foreign body was performed in 43%, and an operation was required in 12%. If the foreign body reached the stomach, 80% of these subsequently passed unimpeded, and 20% required either endoscopic or surgical removal. The most common foreign bodies were coins (15%) or bones (15%). In the group requiring surgery, 7% had a perforation, though none of these occurred in coin ingestion.[2]
From a literature review, it seems ingested coins very rarely cause symptoms or complications in adults. Pyloric obstruction due to an ingested coin has been reported in an adult[6] and was successfully treated by endoscopic removal. Zinc-induced copper deficiency has also been reported in patients who ingest multiple coins, which are usually retained in the stomach.[7,8] Once beyond the stomach, complications of foreign body ingestion seem dependent on the size and nature of the foreign body, but complications from coins in the lower gastrointestinal tract are very rare. Perforation of a Meckel's diverticulum, by coin ingestion, has been reported in a 25-year-old woman, who underwent subsequent excision of the diverticulum and removal of the coin. Although colonic perforation has been reported with chicken bone ingestion,[9] there are no reports of similar occurrences with colonic coins..."