Perchlorate, << pur KLAWR ayt, >> is a chemical ion used to make rocket fuel and other products that is also widely known as a controversial pollutant. An ion is an atom or group of atoms with an electric charge. The perchlorate ion has a negative charge. Its chemical formula is ClO4–. Perchlorate dissolves easily in water and is a strong oxidizer—that is, it reacts chemically by removing electrons from other atoms. Perchlorate occurs naturally in some dry environments. It can also be artificially produced.
Manufacturers have made and used perchlorate salts (ionic compounds containing perchlorate) since the 1890’s, but industrial production increased in the 1940’s due to military demand. Perchlorate salts are used in products such as fireworks, matches, ammunition, and automotive air bags. Perchlorate salts are also used in a variety of industrial processes. Ammonium perchlorate (NH4ClO4) serves as a primary ingredient of solid rocket fuel.
In the human body, perchlorate blocks the absorption of iodine by the thyroid gland. The thyroid gland, a small organ in the neck, uses iodine to produce a hormone necessary for many bodily functions, including growth and development. In the 1950’s and 1960’s, physicians used perchlorate to treat hyperthyroidism, the overproduction of thyroid hormone. This practice largely stopped after several patients developed severe blood disorders, and as better drugs were developed.
Because perchlorate dissolves easily in water, the chemical can easily contaminate ground water (water held beneath the ground) and drinking water. Scientists have detected perchlorate contamination in many countries around the world. Such contamination is common in areas that have many large-scale users and manufacturers of perchlorate. One such area is the southwest United States. Human beings are exposed to perchlorate primarily through drinking contaminated water or eating contaminated food. Experts disagree on the level of perchlorate contamination that poses a risk to human health.
