Scientists began identifying widespread perchlorate contamination in the United States following the development of an analytical method in 1997, which lowered quantitation levels from parts per hundreds to 4 µg/L (micrograms per liter) (California EPA, 2015; ITRC, 2005). Drinking water samples collected in the states as part of perchlorate's 1999 listing on the Unregulated Contaminant Monitoring Rule showed that 1.9% of the 34,728 water supplies sampled contained perchlorate at concentrations ranging from 4 to 420 µg/L (Brandhuber, et al., 2009). As of 2009, detection of perchlorate in soil, surface water, and/or drinking water wells had been reported in 45 states, the District of Columbia, and three territories (GAO, 2010).
Perchlorate salts have been used in a wide variety of applications, including explosives, stick matches, highway safety flares, fireworks and other pyrotechnics. Ammonium perchlorate manufactured for use in solid propellant rockets and missiles makes up the largest proportion of perchlorate by volume of U.S. production (ITRC, 2005). Sodium perchlorate is also used as a bleaching agent in the production of paper and pulp. As of 1998 perchlorate manufacturing facilities and users have been identified in at least 44 states (EPA, 1998).
Environmental contamination has been frequently associated with rocket manufacturers or military facilities. One of the largest identified releases occurred at a former rocket fuel production facility in Henderson, Nevada, that exploded in 1988. The resulting release contaminated the groundwater, which flows into the Las Vegas Wash, located near Lake Mead, and the Colorado River, which both serve as public water supplies (EPA, 2020).
Figure 1. USGS scientists collect soil, plant, and other samples to determine how natural perchlorate from the atmosphere occurs in soil (Source: USGS, 2014).
To a limited extent, perchlorate also occurs naturally. For example, caliche1 deposits in northern Chile contain about 0.1% perchlorate (Erickson, B., 2004). The caliche is a source of naturally occurring sodium nitrate, which is used as a nitrogen source in fertilizer (Urbansky, et al., 2001). As a result, perchlorate has been detected in fertilizers derived from the Chilean caliche (Collette, et al., 2003). Perchlorate also forms naturally in the atmosphere. As it is flushed out of the atmosphere by rain or from dry deposition of airborne particles, perchlorate can be deposited in soil and surface water (Dasgupta, et al., 2005; USGS, 2014). Thousands of years of atmospheric deposition and concentration through evaporation have resulted in soils with salt-rich zones containing perchlorate in the Southwestern U.S. (Rao, B., et al., 2007).
A survey of drinking water wells in western Texas showed perchlorate to be present in more than 80% of the wells tested over 60,000 square miles. Most of the levels of perchlorate found were quite low, but ~25% were equal to or greater than 4 µg/L. Researchers at Texas Tech University concluded that the source of perchlorate was likely atmospheric deposition or surface oxidation, and not anthropogenic in nature (e.g., rocket fuel, flares, fireworks, explosives, and Chilean fertilizer) (Erickson, 2004; Jackson, 2004).
Perchlorate is known to accumulate in some plants, especially leafy green vegetables and tobacco plants, as a result of plant uptake from soil, fertilizer, or irrigation water containing perchlorate (ATSDR, 2008; Huber, et al., 2010). Studies have shown that perchlorate is present in a range of food products and human and dairy milk (Kirk, et al., 2003). Levels can vary widely within a single food based on where it is grown and the amount of perchlorate in the water (U.S. Food and Drug Association [FDA], 2017). Other studies found that perchlorate concentrations in drinking water are not correlated with perchlorate concentrations in breast milk (Kirk, et al., 2013). As part of its Total Diet Study, the FDA found that 74% of samples of 285 foods contained detectable levels of perchlorate (Murray, et al., 2008).
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Collette, T.W., et al., 2003. Analysis of Hydroponic Fertilizer Matrixes for Perchlorate: Comparison of Analytical Techniques. The Analyst. 128(1), pp. 88-97.
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Erickson, B.A, 2004. Tracing the Origin of Perchlorate. Analytical Chemistry, 388A-389A.
Huber, D., et al., 2010. Estimating Perchlorate Exposure From Food and Tap Water Based on US Biomonitoring and Occurrence Data. Journal of Exposure Science and Environmental Epidemiology. 21, pp 395-407.
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Jackson, W.A., K. Rainwater, T. Anderson, T. Lehman, R. Tock, S. Rajagopalan, and M. Ridley, 2004. Distribution and Potential Sources of Perchlorate in the High Plains Region of Texas. Texas Tech University Water Resources Center, 186 pp.
Kirk, A.B., Dyke, J.V., Ohira, S., and P.K. Dasgupta, 2013. Relative Source Contributions for Perchlorate Exposures in a Lactating Human Cohort. Science of the Total Environment. 443:939-943. doi:10.1016/j.scitotenv.2012.11.072.
Kirk, A.B., Smith E.E., Tian K, Anderson, T.A., and P.K., Dasgupta, 2003. Perchlorate in Milk. Environmental Science and Technology. 37(21):4979-4981. doi:10.1021/es034735q.
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Nevada Division of Environmental Protection Bureau of Corrective Actions, 2011. Southern Nevada Perchlorate Cleanup Project.
Rao, B., et al., 2007. Widespread Natural Perchlorate in Unsaturated Zones of the Southwest United States. Environmental Science & Technology. Volume 41(13), pp. 4522-4528.
Urbansky E.T., S.K. Brown, M.L. Magnuson, and C.A. Kelty, 2001. Perchlorate Levels in Samples of Sodium Nitrate Fertilizer Derived from Chilean Caliche. Environmental Pollution. 112(3):299-302.
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USGS, 2014. Natural Perchlorate Levels in a Desert Ecosystem. Communications and Publishing, April.
Demonstration of Perchlorate-Free Projectiles
SERDP & ESTCP blog post, March 18, 2020
Reductions of Perchlorate in Drinking Water
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Review of Perchlorate Occurrence in Large Public Drinking Water Systems in the United States of America.
Luis, S.J., E.A. Miesner, C.L. Enslin, and K. Heidecorn.
Water Supply 19(3): 681-694(2019)
Exploratory Data on Perchlorate in Food
U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 2018
Soil, Plant, and Terrain Effects on Natural Perchlorate Distribution in a Desert Landscape
Andraski, B.J., W.A. Jackson, T.L. Welborn, J.K. Boehlke, R. Sevanthi, and D.A. Stonestrom. Journal of Environmental Quality 43:980-994 (2014)
Evaluation of Alternative Causes of Wide-Spread, Low Concentration Perchlorate Impacts to Groundwater
Cox, E., M. Watling, and W. Robarge. SERDP Project ER-1429, 104 pp, 2011
Perchlorate Data for Streams and Groundwater in Selected Areas of the United States, 2004
Kalkhoff, S.J., S.J. Stetson, K.D. Lund, R.B. Wanty, and G.L. Linder.
USGS Data Series 495, 52 pp, 2010
Perchlorate Occurrence Is Widespread At Varying Levels; Federal Agencies Have Taken Some Actions to Respond to and Lessen Releases Assessment Guidance for Perchlorate
Government Accountability Office, GAO-10-769, 63 pp, 2010
Evaluation of Alternative Causes of Widespread, Low Concentration Perchlorate Impacts to Groundwater: Interim Report
SERDP Project ER-1429, Document TR0197, 132 pp, 2008
Development of Environmental Data for Navy, Air Force, and Marine Munitions
J.L. Clausen, C.L. Scott, and R.J. Cramer. ERDC/CRREL TR-07-7, 62 pp, 2007
Evaluation of Perchlorate Contamination at a Fireworks Display Dartmouth, Massachusetts
Massachusetts Department of Environmental Protection, 37 pp, 2007
Perchlorate in Pleistocene and Holocene Groundwater in North-Central New Mexico
Environmental Science & Technology 40(6):1757-1763(2006)
Alternative Causes of Widespread, Low Concentration Perchlorate Impacts to Groundwater
Smith, B. and R. Holst. SERDP White Paper, 54 pp, 2005
Known Perchlorate Releases in the U.S.
U.S. EPA, Office of Federal Facilities Restoration and Reuse, 7 pp, 2005
Perchlorate Occurrence Mapping
Brandhuber, P. and S. Clark. American Water Works Association, 38 pp, 2005
Report to the Congress: Perchlorate in the Southwestern United States
DoD, The Office of the Secretary of Defense, Under Secretary of Defense, Acquisition, Technology & Logistics. 155 pp, 2005
California Perchlorate Study Discovery Areas
Meyer, K. EPA Region 9, 1 pp, 2004
Distribution and Potential Sources of Perchlorate in the High Plains Region of Texas
Jackson, W.A., K. Rainwater, T. Anderson, T. Lehman, R. Tock, S. Rajagopalan, and M. Ridley. Texas Tech University Water Resources Center, 186 pp, 2004
Perchlorate Drinking Water Impacts and Sources US EPA Region 9
Mayer, K. EPA Region 9, 1 pp, 2004
Perchlorate in the Lower Umatilla Basin Groundwater Management Area – Issues and Answers
Richerson, P. Oregon Department of Environmental Quality, DEQ 04-ER-011b, 3 pp, 2004
Perchlorate Manufacturers and Users as of April 2003
Mayer, K., EPA Region 9, 1 pp, 2003
Perchlorate Environmental Contamination: Toxicological Review and Risk Characterization (External Review Draft). Archived.
EPA Office of Research and Development, National Center for Environmental Assessment, 1 pp, 2002
Perchlorate in Drinking Water: Scientific Collaboration in Defining Safety. Special Report
Juberg, D.R., and J. Stier. American Council on Science and Health, 40 pp, 2002
Survey of Fertilizers and Related Materials for Perchlorate (ClO4-): Final Report
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Mayer, K. EPA Region 9, 14 slides
Perchlorate Occurrence in Nevada
Pohlmann, B.L., Nevada Department of Conservation and Natural Resources Division of Environmental Protection, 11 slides