The RCRA 8 Metals - and Then Some Quiz

Answer: Resource Conservation and Recovery Act

Enacted by the US Congress in 1976, the Resource Conservation and Recovery Act (RCRA) was passed as a measure to regulate the handling and disposal of solid waste in the United States. The law empowered the Environmental Protection Agency (EPA)to identify and regulate the presence of particular hazardous substances in waste.

The EPA named eight metallic elements of special concern. Dubbed the RCRA 8 these heavy metal elements are extremely toxic to humans, even in very small amounts.

Answer: Selenium

Mining, agriculture, and semiconductor processing can discharge compounds which bond with naturally-occurring selenium in the soil to form compounds which can be very toxic and can taint ground water and even plants grown in the affected soil. Symptoms of selenium poisoning include gastrointestinal disorders, loss of hair and nails, fatigue, and, in more serious cases, neurological damage, cirrhosis of the liver, pulmonary edema, or even death.

Answer: Chromium

As with many metals, small amounts of chromium and certain chromium compounds are benign, even beneficial. Chromium and its compounds are used in electroplating, metal alloys (stainless steel), paints, ceramics, lumber processing, tannery, and assorted chemicals. Certain chromium compounds are very toxic, and in the form of chromates can cause allergies, destruction of bone marrow, liver failure, cancers, dementia, and even DNA damage that can be passed down to future generations.

The contamination of water supplies by chromium VI formed the plot of the film "Erin Brockovich", released in 2000.

Answer: Arsenic

The toxic properties of arsenic have ironically contributed to its commercial uses as a pesticide and in such applications as lumber processing, battery manufacture, weapons development, and ironically in producing animal feed. Certain arsenic compounds are even used in medicines and in treatments for diseases such as cancer.

However, the effluent from industries which have used arsenic poses a serious threat to groundwater. Arsenic toxicity can lead to various cancers and heart disease.

Answer: Cadmium

Cadmium was historically used in mining, electroplating, nuclear power generation, and in the production of pigments, photoconductors, and batteries. Because of cadmium's toxicity, it has been replaced in batteries by other compounds. Cadmium is another major component of tobacco smoke. Cadmium exposure is associated with a large number of illnesses including kidney disease, atherosclerosis, hypertension, and cardiovascular disease.

Answer: Silver

Used primarily in the manufacture of coins, jewelry, dental fillings, flatware, mirrors, musical instruments, and catalytic agents and equipment, silver is also used in cloth processing, medical treatments, photography, and biological laboratories. Exposure to silver salts can cause argyria, a permanent skin discoloration.

Answer: Mercury

Despite its widespread uses, mercury has always been recognized as extremely toxic. It has been used in medical devices, lighting, gold production, smelting, and the manufacture of steel, cement, and caustic soda. Mercury poisoning can damage major organs such as the brain, kidneys, and lungs, resulting in tremors, hallucinations, muscle spasms, and respiratory failure.

Answer: Barium

Familiar as the barium sulfate "cocktail" safely administered to patients as part of x-ray studies of the intestine, barium and its compounds have also been used in the manufacture of petroleum, metals, lighting, ceramics, optics, superconductors, ammunition, and even fireworks. Barium is highly toxic. It can cause nervous system and heart malfunctions and damage to the immune system.

Answer: Lead

Lead has been used in the manufacture of ammunition, insulation, ships, glassware, paints, batteries, petrochemicals, and radiation shielding. Its toxic effects have been known since at least the fifteenth century. It can be stored in the bones, and thus its effects can outlive initial exposure. Lead can cause brain and kidney damage, anemia, miscarriage, and neuropathy.

Answer: Iron

The five most prevalent heavy metals in the body are iron, zinc, lead, copper, and tin, in that order. Note that lead, while one of the RCRA 8, is also present in small amounts (less than 2 percent) in the healthy human. However, iron and zinc together account for over ninety percent of the metals in the body.