Washington State Department of Ecology

Major Contaminants

Glossary

Radioactive Isotopes

Toxic Chemicals

Radioactive Isotopes

Cesium-137

Description

One of the more well-known byproducts of nuclear fission
Emits beta and relatively strong gamma radiation
Half-life is 30 years
One of most common isotopes used in industry (moisture-density gauges, well-logging devices, thickness gauges, etc.)
Liquid at room temperature, combines easily with chlorides to form a powder.

Health Concerns

Exposure can be through ingestion, inhalation, or just being near it (since it emits gamma radiation)
In humans, is flushed from the body fairly quickly.

Exposure Levels

EPA has established a maximum contaminant level of 4 millirem per year for beta particle and photon radioactivity from man-made radionuclide's in drinking water. Cesium-137 would be covered under this MCL. The average concentration of cesium-137 which is assumed to yield 4 mrem/year is 200 picocuries per liter. If other radionuclide's which emit beta particles and photon radioactivity are present, the sum of the annual dose from all the radionuclide's must not exceed 4 mrem/year.

Strontium-90

Description

Considered one of the more hazardous constituents of nuclear waste
Moderate beta emitter
Half-life is 29.1 years
Biologically acts like calcium--lodges in bones, teeth, and bone marrow

Health Concerns

In humans, can cause cancer in bones and blood.
Can also cause anemia, abnormal bleeding, and inability to fight diseases.
Chemically very reactive; is only found in compounds in nature.
Rapidly reacts to air, can burst into flame if finely cut.

Exposure Levels
Exposure to strontium-90, as to all radionuclide's, results in increased risk of cancer. EPA has established a maximum contaminant level of 4 millirem per year for beta particle and photon radioactivity from man-made radionuclide's in drinking water. Strontium-90 would be covered under this MCL. The average concentration of strontium-90 which is assumed to yield 4 mrem/year is 8 picocuries per liter. If other radionuclide's which emit beta particles and photon radioactivity are present, the sum of the annual dose from all the radionuclide's must not exceed 4 mrem/year.

Technetium-99

Description

A main constituent of nuclear waste
Weak beta emitter
Long half-life —212,000 years
Water soluble and mobile
Can be taken up by plants
melting point is 3,942 °F, boiling point is 8,811 °F
very dense --at room temperature, weighs 11.5 times as much as water.
Is not captured by same processes used for cesium-137 and strontium-90 because its chemistry is different
Good corrosion inhibitor and superconductor at low temperatures
Has no significant industrial use, though shorter-lived parent, Tc-99m, is the most widely used radioactive isotope for medical diagnostic studies.

Health Concerns

Exposure is through ingestion of contaminated water or plants.
In humans, concentrates in thyroid and gastrointestinal tract, but body excretes it quickly, ½ of it every 60 hours.

Exposure Levels
Exposure to technetium-99, as to all radionuclide's, results in increased risk of cancer. EPA has established a maximum contaminant level of 4 millirem per year for beta particle and photon radioactivity from man-made radionuclide's in drinking water. Technetium-99 would be covered under this MCL. The average concentration of technetium-99 which is assumed to yield 4 mrem/year is 900 picocuries per liter. If other radionuclide's which emit beta particles and photon radioactivity are present, the sum of the annual dose from all the radionuclide's must not exceed 4 mrem/year.

Tritium

Description

A radioactive form of hydrogen with two neutrons. (Nonradioactive hydrogen has none.) Weak beta emitter.
Half-life is 12.3 years.
Bonds to oxygen to create irradiated water molecules, called “tritiated” water.
Almost always found in water
Highly mobile.
Widely used in industry for illuminated signs and dials, biochemical research tracers, and more.

Health Concerns

Exposure is via ingesting tritium contaminated water, skin contact, and inhalation (of gaseous tritium)
In humans, is excreted through urine within a month or so.

Exposure Levels

Exposure to tritium, as to all radionuclide's, results in increased risk of cancer. EPA has established a maximum contaminant level of 4 millirem per year for beta particle and photon radioactivity from man-made radionuclide's in drinking water. Tritium would be covered under this MCL. The average concentration of tritium which is assumed to yield 4 mrem/year is 20,000 picocuries per liter. If other radionuclide's which emit beta particles and photon radioactivity are present, the sum of the annual dose from all the radionuclide's must not exceed 4 mrem/year.

Uranium-238

Description

All uranium isotopes are radioactive.
Alpha and weak gamma emitter
Very long half-life: 4.5 billion years
Has a long series of decay products, raising health concerns
Extremely dense and heavy metal

Health Concerns

Chemically as well as radioactively toxic.
Greatest health risk is from toxic damage to kidneys.
Can accumulate in bones
In humans, the body excretes more than 99%.
If inhaled, can cause lung cancer

Exposure Levels

EPA maximum level for drinking water is 30 µg/L (micrograms/liter)

Iodine-129

Description

Extremely weak beta emitter
Very long half-life: 15.7 million years
Water soluble, and moves easily from atmosphere to living creatures.

Health Concerns

When ingested, most passes from body. The rest goes to the thyroid.
In humans, ½ of remaining iodine leaves the body every 100 days.
Long-term chronic doses can cause thyroid cancer.

Exposure Levels

Exposure to iodine-129, as to all radionuclide's, results in increased risk of cancer. EPA has established a maximum contaminant level of 4 millirem per year for beta particle and photon radioactivity from man-made radionuclide's in drinking water. Iodine-129 would be covered under this MCL. The average concentration of iodine-129 which is assumed to yield 4 mrem/year is 3 picocuries per liter. If other radionuclide's which emit beta particles and photon radioactivity are present, the sum of the annual dose from all the radionuclide's must not exceed 4 mrem/year.

Toxic Chemicals

Carbon tetrachloride

Description

moves readily through soil
Colorless, clear, heavy liquid; sweet aromatic odor similar to chloroform
Carbon tetrachloride has a low potential to bioaccumulate.
Evaporates quickly
Breaks down very slowly
When it breaks down it forms compounds, such as chloroform, that destroy ozone in upper atmosphere
Was used for aerosol propellant, dry cleaning agents, rubber cement, refrigerator coolants, cleaning and degreasing fluids, and in fire extinguishers. These uses now banned due to health risk.
Not naturally in environment

Health Concerns

Probably carcinogenic
Long-term exposure can cause damage to liver, kidney and central nervous system. Acute exposure can cause liver kidney and lung damage when people are exposed to it in drinking water at levels above the EPA drinking water standard for relatively short periods of time.

Exposure Levels

EPA maximum level for drinking water 5 parts per billion

Chromium VI

Description

Chromium is a naturally occurring element found in rocks, animals, plants, soil, and in volcanic dust and gases. Chromium is present in the environment in several different forms. The most common forms are chromium(0), trivalent (or chromium (III)), and hexavalent (or chromium (VI)). Chromium (III), however, is an essential nutrient for humans.
“Hexavalent” chromium has six fewer electrons than normal chromium.
One of the few toxic chemicals considered a carcinogen.
No taste or odor
Not readily soluble in water
Binds to soil
High potential for accumulation of chromium in aquatic life, including salmon.
Hexavalent chromium is the substance against which Erin Brockovich campaigned.
Fish do not accumulate much chromium in their bodies from water.

Health Concerns

Causes lung cancer in humans
Less carcinogenic if ingested, because stomach acids may convert it to nontoxic form Short-term exposure can cause skin irritation or ulceration. Long-term exposure at levels above the MCL can cause damage to liver, kidney circulatory and nerve tissues, and skin irritation
Direct eye contact with chromic acid or chromate dusts can cause permanent eye damage. Hexavalent chromium can irritate the nose, throat, and lungs. Repeated or prolonged exposure can damage the mucous membranes of the nasal passages and result in ulcers. In severe cases, exposure causes perforation of the septum (the wall separating the nasal passages).

Exposure Levels

EPA maximum level for drinking water is 0.1 ppm.

Nitrates

Description

Nitrates and nitrites are nitrogen-oxygen chemical units that combine with various compounds. Once taken into the body, nitrates are converted into nitrites.
The greatest use of nitrates is as a fertilizer.
Chemically interchangeable with nitrites
Very soluble, do not bind to soils or evaporate, travels easily in groundwater

Health Concerns

Interferes with blood’s ability to carry oxygen.
Excessive levels of nitrate in drinking water have caused serious illness and sometimes death.
In babies and children, exposure can cause shortness of breath and blueness of skin, when conversion of nitrates to nitrites interferes with oxygen-carrying capacity of child’s blood. Can be acute, and health can deteriorate in a matter of days.
Low blood-oxygen levels especially harmful to brain and heart.
Long-term exposure can cause increased starchy deposits and hemorrhaging of the spleen.

Exposure Levels

EPA maximum level for drinking water for nitrates is 10 ppm and 1 ppm for nitrites. http://www.epa.gov/safewater/dwh/c-ioc/nitrates.html

Trichloroethylene

Description

Used for a solvent
Very volatile
Production of trichloroethylene increased from just over 260,000 lbs in 1981 to 320 million lbs. in 1991. Vapor degreasing of fabricated metal parts and some textiles accounts for 80% of its use.
Clear, colorless or blue mobile liquid with sweet chloroform-like odor
Forms phosgene gas and hydrogen chloride, both toxic if inhaled.

Health Concerns

EPA has found trichloroethylene to potentially cause vomiting and abdominal pain from acute exposures at levels above the MCL.
Trichloroethylene has the potential to cause liver damage from a lifetime exposure at levels above the MCL.
Lodges in blood stream and fatty tissues
Toxicity affects many internal organs
There is some evidence that trichloroethylene may have the potential to cause cancer from a lifetime exposure at levels above the MCL.

Exposure Levels

EPA maximum level for drinking water is 0.005 mg/L.
The goal for drinking water for this contaminant is zero.

Glossary