What are Perchlorates?

Perchlorates are colorless and odorless salts that dissolve easily in water. There are five perchlorate salts that are manufactured in large amounts:

• Magnesium perchlorate
• Potassium perchlorate
• Ammonium perchlorate
• Sodium perchlorate
• Lithium perchlorate

Perchlorates are very reactive chemicals that are used mainly in explosives, fireworks, and rocket motors. Among other places, perchlorates occur naturally in saltpeter deposits in Chile, where saltpeter is used to make fertilizer. Perchlorates are also used for making other chemicals and were used many years ago as a medication to treat an over-reactive thyroid gland.

Perchlorates and the Environment

Perchlorates can enter the environment in and around sites where rockets are made, tested, and taken apart. Perchlorates have also been found in milk and food. Factories that make or use perchlorates may also release them into soil and water. Perchlorates will not stay in soil and will wash away with rain water. Perchlorates do eventually end up in ground water. While it is not known exactly how long perchlorates last in water and soil, the information available indicates that it is a very long time.

Perchlorate Exposure

Perchlorate exposure may occur in any of the following ways:

• Drinking water that is contaminated with perchlorates. Most contaminated water supplies are found near hazardous waste sites where perchlorates are found.

• Eating food or drinking milk contaminated with perchlorates.

• Living near factories that make fireworks, flares, or other explosive devices.

• Smoking or chewing tobacco, because a variety of tobacco products contain perchlorates.

• Living near a waste site or a rocket manufacturing or testing facility.

Perchlorate Health Effects

The health effects of perchlorate salts are due to perchlorate itself, and not to the other components (i.e., magnesium, potassium, ammonium, sodium, lithium).

Perchlorate affects the ability of the thyroid gland to take up iodine, an important chemical needed to make hormones that regulate many body functions after they are released into the blood. There is concern that people exposed to high amounts of perchlorate for a long time may develop a low level of thyroid activity (hypothyroidism). Low levels of thyroid hormones in the blood can lead to adverse effects on the skin, cardiovascular system, pulmonary system, kidneys, gastrointestinal tract, liver, blood, neuromuscular system, nervous system, skeleton, male and female reproductive system, and numerous endocrine organs.

In spite of these concerns, studies have shown that health problems are unlikely at lower levels of perchlorate exposure. For instance, in one study, healthy volunteers took 35 milligrams (mg) of perchlorate every day for 14 days, and showed no signs of abnormal functioning of their thyroid gland or any other health problem. Other studies involving workers exposed for years to approximately the same amount of perchlorates found no evidence of alterations in the worker's thyroids, livers, kidneys, or blood.