A clear need, therefore, exists for properly controlled
randomized trials and epidemiologic studies to better
define the tolerable levels of copper in drinking water.
According to the recent data by Pizarro et al. (1999) nausea
is the most likely symptom to be observed. Nausea
is a nonspecific manifestation, strongly influenced by
psychological and environmental (cultural) factors. Individuals
living in three sites of different cultural backgrounds
were studied: Santiago in Chile; Grand Forks,
North Dakota, in the United States; and Coleraine in
Northern Ireland.