CHAPTER 2-55: COPPER

INTRODUCTION

Copper is widely used in its elemental metallic form, in metal alloys, and in the form of copper salts. Each of the copper forms has different physical properties, resulting in different toxicities. Elemental metallic copper is used in electrical wiring and plumbing materials and was formerly the main constituent of pennies (now mostly zinc). Copper salts such as copper sulfate, copper oxide, copper chloride, copper nitrate, copper cyanide, and copper acetate are used as pesticides and algaecides and in a variety of industrial processes. Because of its toxicity, copper sulfate is no longer used as an emetic. Copper levels may be elevated in persons who drink from copper containers or use copper plumbing. The increased acidity of beverages stored in copper alloy (eg, brass or bronze) containers enhances leaching of copper into the liquid.

MECHANISM OF TOXICITY

1. Elemental metallic copper is poorly absorbed orally and is essentially nontoxic. However, inhalation of copper dust or metallic fumes created when copper alloys are welded or brazed may cause chemical pneumonitis or a syndrome similar to metal fume fever. Metallic copper dust in the eye (chalcosis) may lead to corneal opacification, uveitis, ocular necrosis, and blindness unless the dust is removed quickly.

2. Copper sulfate salt is highly irritating, depending on the concentration, and may produce mucous membrane irritation and severe gastroenteritis.

3. Systemic absorption can produce hepatic and renal tubular injury. Hemolysis has been associated with copper exposure from hemodialysis equipment or absorption through burned skin.

TOXIC DOSE

Copper is an essential trace metal. The daily adult requirement of 2 mg is supplied in a normal diet.

1. Inhalation. The recommended workplace limit (ACGIH TLV-TWA) for copper fumes is 0.2 mg/m³; for dusts and mists, it is 1 mg/m³. The air level considered immediately dangerous to life or health (IDLH) for dusts or fumes is 100 mg/m³.

2. Ingestion of more than 250 mg of copper sulfate can produce vomiting, and larger ingestions potentially can cause hepatic and renal injury.

3. Water. The US Environmental Protection Agency (EPA) has established a safe limit of 1.3 mg/L in drinking water under the Lead and Copper Rule. According to the EPA, this has led to the reduction in risk of copper exposure that can cause stomach and intestinal distress, liver or kidney damage, and complications of Wilson disease in genetically predisposed people. The WHO (World Health Organization, 2004) guideline value for drinking water is 2 mg/L.

CLINICAL PRESENTATION

1. Inhalation of copper fumes or dusts initially produces a metallic taste and upper respiratory irritation (dry cough, sore throat, and eye irritation). Large exposures may cause severe cough, dyspnea, fever, leukocytosis, and pulmonary infiltrates (see also "Metal Fume Fever").

2. Ingestion of copper sulfate or other salts causes the rapid onset of nausea and vomiting with characteristic ...