Re: Why is it unsafe to cook in copper, but safe for house water pipes?

Actually it isn't necessarily unsafe to cook in copper - the problem lies 
with what is cooked... We used to use copper alot in cookware. It would be 
plated to avoid oxidation and discoloration problems in the prepared food. 
Acidic foods and liquids cause the copper salts to leach out of the metal 
and into the food item. This results in acute copper poisoning.

Principle features of poisoning by ingested copper compounds have been:
- gastrointestinal irritation, abdominal pain and diarrhea, sometimes with 
blood.
-headache, sweating, weakness, and sometimes shock (and you chalked it all 
up to finals... :) )
-liver enlargement and jaundice
-destruction of red cells and presence of abnormal hemoglobin
-elevated levels of albumin (a form of protein) in urine, hemoglobin in 
the urine and sometimes acute renal failure.

Trace amounts of copper are needed in our diet, particularly in the 
formation of hemoglobin. It is also believed to have some benefit (by 
some) 
with the immune system. It takes very little excess though to cause 
problems. This is a Law in Medicine which repeats itself time and time 
again - "too little or too much and too bad."

As long as water is not too "soft" or acidic it can be safely transferred 
through copper pipes. I did find something of interest regards carbonated 
soda machines. They have a device attached to prevent backwash of 
carbonated liquid into the copper supply lines. An example would be the 
CONBRACO NEW ASSE-APPROVED CARBONATED BEVERAGE BACKFLOW PREVENTER !!! You 
gotta love devices with descriptive titles.

Hope this is useful

GWB

Ref: www.broadasthealth.com
     http://hsis.fedworld.gov/PPH/
53018.htm
     Food Safety and Hygiene, Food Science Australia, Feb 2000 bulletin.
     (web address for above) www.dfst.csiro.au/fshbull/fshbull20.htm