Perchlorate is a naturally occurring and man-made anion that consists of one chlorine atom bonded to four oxygen atoms (ClO4–). Manufactured forms of perchlorate include perchloric acid and salts such as ammonium perchlorate, sodium perchlorate and potassium perchlorate (EPA FFRRO 2005; ITRC 2005).
Perchlorate is commonly used in solid rocket propellants, munitions, fireworks, airbag initiators for vehicles, matches and signal flares (EPA FFRRO 2005; ITRC 2005). It is also used in some electroplating operations (ATSDR 2008; ITRC 2005).
90 percent of the domestically produced perchlorate is manufactured for use in the defense and aerospace industries, primarily in the form of ammonium perchlorate (GAO 2005; ITRC 2005).
Perchlorate may occur naturally, particularly in arid regions such as the southwestern United States and as a natural impurity in nitrate salts from Chile, which are used to produce nitrate fertilizers, explosives and other products (EPA FFRRO 2005; ITRC 2005)
The US FDA approved perchlorate use in food packaging in 2005 (not to exceed 1.2 percent by weight of the finished polymer) as a component in certain containers and food processing equipment for use in contact with certain types of dry foods.
Known Effects of Perchlorates in Water on Human Health
Primary pathways for human exposure to perchlorate are ingestion of contaminated food and drinking water. After perchlorate is ingested, it quickly passes through the stomach and intestines and enters the bloodstream.
The thyroid gland is the primary target of perchlorate toxicity in humans. Thyroid hormones play an important role in regulating metabolism and are critical for normal growth and development in fetuses, infants and young children.
Perchlorate can interfere with iodide uptake into the thyroid gland at high enough exposures, disrupting the functions of the thyroid and potentially leading to a reduction in the production of thyroid hormones.
Since thyroid hormone is required for development and function of many tissues in the body, including the brain, many consider perchlorate a serious threat to human health.
Recent research suggests that co-exposure to Nitrate and Perchlorate can alter thyroid function as well: CO-occurring exposure to perchlorate, nitrate and thiocyanate alters thyroid function in healthy pregnant women – ScienceDirect
How to Address Perchlorate in Drinking Water
Like many contaminants, Perchlorates can be addressed through a number of technological pathways. The key is to specify treatment methods with an understanding of the pre and post-treatment requirements while also taking a layered approach – never depending on only one methodology to address the contaminant.
Ion Exchange using perchlorate-selective or nitrate-specific resins is a proven method for removal of perchlorate from drinking water, groundwater, and surface water.
Reverse Osmosis as a separation method that has been proven highly effective, especially when utilizing Ion Exchange pretreatment.
Additional Reading
EPA’s 2008 Interim Guidance on Perchlorates
Technical Fact Sheet – Perchlorate (epa.gov)
Perchlorate | Department of Toxic Substances Control (ca.gov)