Questions and Answers

Perchlorate Basics

Q: What is perchlorate?

In the 1950's perchlorate was approved by the U.S. Food and Drug Administration as a safe and effective medication to treat people with overactive thyroid glands.

A: Perchlorate is a simple salt-like substance made up of chlorine and oxygen. It is found in nature and can be man-made.


Back to Top


Q: Is it true that perchlorate was used as a medicine?

A: Yes, in the 1950s perchlorate was approved by the U.S. Food and Drug Administration as a safe and effective medication to treat people with overactive thyroid glands. While it has been replaced in the U.S. with newer medications (partly because it took enormously high doses to have any effect, and these doses had to be given frequently because perchlorate is so rapidly eliminated from the body1) perchlorate still is used as a medicine in other parts of the world. Because of its longstanding use as a medicine, we know much today about how perchlorate works in the body.


Back to Top


Q: What are perchlorate's other uses?

A: Perchlorate is widely used today by the military, NASA and the commercial space industry as an ingredient in solid rocket fuel and explosives. Perchlorate also is used as a component in safety flares, fireworks, auto air bag inflators, lubricating oils and aluminum refining. Perchlorate is naturally present in some fertilizers typically used in organic farming.


Back to Top


Q: Is perchlorate also found naturally in fertilizer?

A: Yes, since the early 20th century Chilean nitrate fertilizer containing naturally-occurring perchlorate has been widely used in American agriculture. Current amounts of Chilean nitrate fertilizer products being shipped and used in the United States are substantial. According to the Foreign Trade Division, U.S. Census Bureau, the amounts of sodium nitrate imported from Chile into U.S. ports in 2001 was 88,150 metric tons. Specific to California, Chilean nitrate fertilizer containing perchlorate has been widely used since 1923 and between 1923-1998, the reported usage of sodium nitrate in California was 477,061 metric tons. Though the quantities used today are smaller than the amounts applied earlier in the century, the use of Chilean nitrate fertilizer in California remains substantial. Most recent data (2000 U.S. Department of Census) indicates more than 6,600 tons of Chilean nitrate fertilizer were imported to California that year.


Back to Top

1 In the early 1960s there was a concern that perchlorate might have an association with aplastic anemia. Seven patients who were being treated with perchlorate developed the disease. There were several possible reasons why, ranging from misdiagnosis of hypothyroidism to environmental concerns (the cases were clustered in two specific areas). No evidence of a connection between perchlorate and aplastic anemia has been shown. What is known is that in the four decades since, perchlorate has continued to be used, and no cases of aplastic anemia have arisen among any of these patients.

More Questions and Answers: