Questions and Answers
What is perchlorate?
- Perchlorate is a colorless solid that readily dissolves in water. It refers to both man-made and naturally occurring compounds that are commonly found as ammonium, potassium, and sodium perchlorate.
- Perchlorate salts are used in the production of a variety of commercial products such as road flares, fireworks and household bleach. In addition, perchlorate can occur naturally and is found in some imported fertilizers. It can also be found in water disinfectants and herbicides.
What are the uses of perchlorate?
- Perchlorate is a major component of propellants in solid fuel for rockets and missiles.
- Due to its stability it is among the safest propellants used by the Department of Defense (DoD).
- Perchlorate is used by DoD as an oxidizer in pyrotechnics such as training simulators, flares, hand grenade delays, and aircraft countermeasures.
- Perchlorate is also used as a constituent of explosives, fireworks, and road flares.
- It is used to quickly deploy some automotive air bags.
- Additional uses include the production of matches, dyes, lubricating oils, electroplating, rubber manufacturing, and paint productions.
- One form of perchlorate was once used to treat thyroid disorders in people with Graves' Disease. Potassium perchlorate is still used today under limited conditions to test for thyroid hormone production.
Why has perchlorate become a concern?
- Perchlorate has been found in drinking water and food including milk, fruits, vegetables, and grains triggering concerns about human health
- Findings of the National Academy of Sciences (NAS) 2005 study indicate that populations most at risk from exposure are pregnant women and infants
- Perchlorate has been detected in drinking water sources in at least 34 states according to the EPA.
- New evidence suggests that food rather than drinking water may be as or more significant a source of exposure.
What are the health effects of perchlorate?
- At prolonged and high enough doses, perchlorate is only one of several chemicals that stresses the ability of the thyroid to uptake iodide.
- Because iodide is an essential component in the production of thyroid hormones, perchlorate may affect how the thyroid functions.
- In adults, the thyroid helps to regulate metabolism; in children, the thyroid also plays a role in proper development.
- The National Academy of Sciences risk assessment for perchlorate recommended 0.0007 mg/kg/day as the reference dose for perchlorate, which was adopted by EPA.
- Federal public health agencies continue to evaluate exposure and public health risks from perchlorate; therefore you should review their web sites to keep abreast of current thinking about perchlorate risks and efforts to ensure public health protection.
- The latest health effects information regarding exposure to perchlorate can be found at:
How might I be exposed to perchlorate?
- People may be exposed to perchlorate through contaminated food or drinking water.
- People who consume water from areas proximate to where perchlorate has been used, produced, disposed of may be exposed in their drinking water.
- Another possible form of exposure is by consuming food that has been irrigated with water or fertilized with materials that contain perchlorate.
- Natural sources of perchlorate also exist and may contribute to its presence in food and water.
How will I know if my drinking water is affected by perchlorate?
- Some public water systems sample for perchlorate or are specifically required by EPA to sample. All community water systems must publish and distribute a Consumer Confidence Report (CCR) each year often found under the "Water Report" or "Public Information" link on their websites. You can obtain a copy of reports from your local water supplier anytime. In addition, EPA maintains related data on the following public website. http://www.epa.gov/safewater/data/ucmrgetdata.html
- If you believe that you may have perchlorate in your drinking water, please contact your local/state health department or water utility for additional information.
What are DoD and others doing to identify sources of perchlorate contamination?
- The DoD samples for perchlorate at current DoD and formerly used defense sites when there is both a reasonable basis to suspect the use of perchlorate and a way for people to come into contact with perchlorate.
- EPA, other federal agencies, states, water suppliers and industry are actively addressing this issue by testing for perchlorate in foodstuffs, drinking water, surface water and groundwater.
- DoD researchers have developed a scientific method for detecting the sources of perchlorate which should assist in "fingerprinting" sources. Currently natural and chemically-produced perchlorate can be distinguished. It is likely that further differentiation of "manmade" sources will be possible in the near future.
What happens to perchlorate in the environment?
- In solid form, the perchlorate molecule will adhere weakly to soil particles. Since it dissolves readily in water, it moves easily from soil into groundwater.
- Perchlorate is usually stable in water - it does not break down easily.
- It is persistent in the environment and remains in the water until it is treated.
- In some anaerobic (oxygen-free) conditions, there are microorganisms that can naturally break down the perchlorate molecule. Research has shown that these microorganisms are widespread throughout the environment.
Where has DoD found perchlorate?
- DoD has found large concentrations (plumes) of perchlorate at a limited number of sites. These plumes were found at sites where DoD: tested propellants and rocket motors; cleaned out aged rockets' propellant; historically burned munitions, flares and propellants that were ignited in an unconfined manner; and discharged wastewater from facilities that manufactured munitions over a number of years. Many of these types of releases are now regulated by EPA.
- Nationally, approximately 50,000 samples testing for perchlorate have been collected by DoD at 309 locations. The extensive sampling showed that a vast majority of the samples were well below 4 parts per billion (ppb).
- The data from these samples showed that 56 installations detected perchlorate at some point in time and in some media (i.e., soil, drinking water, ground water, surface water) in excess of DoD management limits.
- DoD perchlorate sampling results are posted. To view, click here.
What has DoD found through collaborating with the State of California on perchlorate?
- In August 2003 DoD and California regulators investigated the presence of perchlorate within 5 miles of drinking water supplies throughout the state to locate previously unidentified threats to public water wells on or near DoD sites.
- Out of the 924 sites screened using a consensus-based protocol 54 sites were determined to merit further review.
- While the sampling protocol excluded some ranges and other sites because they were already being addressed by other mechanisms, the review of the 54 sites led the DoD and California regulators to preliminarily conclude that DoD installations did not appear to be significantly impacting California public drinking water wells. For more information about the California Prioritization Protocol, see Racca, L. et al (December 2008). Attention to Protocol, EM Magazine, or by clicking here.
Is it clear that DoD, as a major consumer of perchlorate, is the source of all perchlorate releases and exposure?
- While DoD is responsible for some isolated large releases of perchlorate, there is mounting evidence that the widespread, low-level detections of perchlorate are associated with a variety of sources not necessarily linked with DoD activities or releases of perchlorate (For more information see: Dasgupta, P.K. et al. (2006). Perchlorate in the United States: Analysis of relative source contributions to the food chain. Environmental Science and Technology. 40(21) pp 6608-6614).
- Perchlorate has been found in sodium hypochlorite used in water and wastewater treatment. (For more information see Kang, N. Et al. (2006). Photochemical formation of perchlorate from aqueous oxychlorine anions. Analytica Chimica Acta. 567 (1), pp 48-56.)
- According to Department of Commerce data, U.S. fireworks importation increased by nearly 100 million pounds over the 5-year period, 2002-2006, to more than 271 million pounds. The American Pyrotechnics Association estimates that perchlorate makes up to 70 percent of the chemical component of fireworks. The amount of perchlorate consumed annually for fireworks exceeds DoD consumption. For example, annual DoD purchases of perchlorate for weapons systems ranged between 6 and 8 million pounds from 2004-2006, and annual training uses (which is confined to certain ranges) of perchlorate is approximately 1.6 million pounds.
- Elevated perchlorate levels in groundwater were found to be associated with the use of explosives in construction in Massachusetts and in 2005 the state wrote in a letter to U.S. EPA that "None of the nine water supplies that have tested positive for perchlorate in Massachusetts appear to have any connection to military bases or activities."
- The use of certain perchlorate-containing fertilizers may also be a significant source. Over 400,000 pounds of this fertilizer is still applied annually in the U.S. Furthermore, perchlorate has been found to be naturally occurring in various geological materials, such as potash ore, Chilean saltpeter, playa crust and hanksite. (For more information, see paper by Dasgupta, above).
- Research demonstrates that perchlorate can be formed by a variety of simulated atmospheric processes which suggests that natural, atmospherically-derived, sources of perchlorate also exist in the environment.
- The situation regarding environmental sources is complex and must be evaluated on a site-by-site basis.
Why is perchlorate still being used by the military?
- Perchlorate ensures force protection, safety and readiness.
- Perchlorate is by far the safest and best performing propellant material cur available because it is an extremely efficient, stable, and reliable oxidizer.
- It is the safest material for handling and storage and has the explosive properties needed for military applications but DoD began using some substitute materials in Army training in 2009.
- No "drop-in" substitutes exist for perchlorate's use in strategic missiles.
What is DoD doing to manage perchlorate?
- To minimize its use and potential release of perchlorate DoD has been developing and testing replacements for perchlorate used in training. DoD reached full manufacturing production capability for new ground burst simulators and hand grenade simulators that account for majority of expended perchlorate on Army Training ranges.
- Other perchlorate-free and low-perchlorate training materials are also nearing production capability.
- DoD strives to comply with state and federal cleanup regulations, and then takes additional protective measures when it has determined that some risks are still unacceptable.