[1] The suggested safe level of copper in drinking water for humans varies depending on the source, but tends to be pegged at 1.3 mg/L.

[3] Acute symptoms of copper poisoning by ingestion include vomiting, hematemesis (vomiting of blood), hypotension (low blood pressure), melena (black "tarry" feces), coma, jaundice (yellowish pigmentation of the skin), and gastrointestinal distress.

[14][15][16] Many of the substances that protect humans from excess copper perform important functions in the neurological and endocrine systems, leading to diagnostic difficulties.

Such symptoms often include mood swings, irritability, depression, fatigue, excitation, difficulty focusing, and feeling out of control.

The U.S. Environmental Protection Agency's Maximum Contaminant Level (MCL) in drinking water is 1.3 milligrams per liter.

[18] Toxicity in mammals includes a wide range of animals and effects such as liver cirrhosis, necrosis in kidneys and the brain, gastrointestinal distress, lesions, low blood pressure, and fetal mortality.

[24] An inherited condition called Wilson's disease causes the body to retain copper, since it is not excreted by the liver into the bile.

An X-linked recessive trait that is inherited named Menke's disease causes disruption of connective tissue due to mutations in genes.

[28] This bound form is thought to mediate the production of reactive oxygen species in the brain.

Excluded are toxic effects of mercury, arsenic, manganese, beryllium, antimony, cadmium, and chromium.

In cases of suspected copper poisoning, penicillamine is the drug of choice, and dimercaprol, a heavy metal chelating agent, is often administered.

[31] There is some evidence that alpha-lipoic acid (ALA) may work as a milder chelator of tissue-bound copper.

[37] In the United States, copper-based paint replaced tributyltin, which was banned due to its toxicity, as a way for boats to control organic growth on their hulls.

Studies have shown that copper concentrations are toxic when marine phytoplankton are confined to areas that are heavily impacted by anthropogenic emissions.

Associated applications include the use of brass doorknobs in hospitals, which have been found to self-disinfect after eight hours, and mineral sanitizers, in which copper can act as an algicide.