Perchlorate: Contamination in Water and an Assessment of Regulations

ABSTRACT

INTRODUCTION

PRODUCTION AND USE

FATE AND TRANSPORT

LEVELS IN ENVIRONMENTAL MATRICES

ECOTOXICOLOGY

DIPOSITION AND METABOLISM

HEALTH EFFECTS

REGULATIONS

REMEDIATION

CONCLUSIONS

Antelope Valley

Coachella

Valley

Colorado River B

asins

Indian Wells

Owens Valle

y

Mojave Area

0

20

40

60

80

100

120

Groundwater Quality Status, 2006-2008

Low or Not Detected Moderate High

Contra Costa

(7)

Fresno (1

0)

Kern (15)

Los A

ngeles (19)

Monterey (27)

Orange (30)

Riversi

de (33)

Sacramento (3

4)

San Bernardino (36)

San Diego (37)

Santa Barbara (42)

Santa Clara (47)

Sutter (51)

Tulare (54)

Ventura (56)

0

20

40

60

80

100

120

7.9 4.514

108

4.8 9

68

13

94

9.9 4.6 10 1020

5.2

Perchlorate Peak Level (µg/L) from 2010-2013

Summary of proposed state drinking water standards or action levels for perchlorate

Country/State PHG/MCLG Proposed Standard Action Level Remarks

Arizona 14Based on child

exposures

California 6 6 Notification level

Maryland 1 Advisory level

Massachusetts 2 1Advisory Level for children and other at-risk populations

for Bourne

New Jersey 5 Health based value

New Mexico 1Drinking water screening level

New York 5Drinking water planning level

Nevada 18Public notice

standard

Oregon 4

Texas 1751

Residential protective clean up level (PCL)

Industrial/commercial PCL

U.S. EPA 15Interim drinking

water health advisory level

Canada 6 Guidance Level

4 µg/L 24 µg/L0

500,000,000

1,000,000,000

1,500,000,000

2,000,000,000

2,500,000,000

Estimate Cost

Perchlorate and its salts are mainly used in solid propellants and for manufacturing matches, rockets, explosives and fireworks. It occurs naturally in certain fertilizers and potash ores. Perchlorate is a white crystalline solid or a colorless liquid. It is highly soluble in water and is a concern in water, soil and food contamination.

REFERENCES

Compounds containing perchlorate include the oxidant in solid rocket fuel as well as that in fireworks, military ordinance, flares, airbags, and other applications where an energetic oxidant is required.

The presence of perchlorate in groundwater and drinking water is a potential health concern because perchlorate can impair proper functioning of the thyroid gland. The thyroid gland produces hormones that are maintained within narrow concentration limits by an efficient regulatory mechanism. Hormones required for normal development of the central nervous system of fetuses and infants are secreted by the thyroid gland. These hormones are required for normal skeletal growth and development.

The perchlorate anion (ClO4-) commonly originates as a contaminant in the environment from the improper disposal of solid salts of ammonium, potassium, or sodium perchlorate.

Perchlorate uptake by plants, trees, forage and edible vegetation is known to occur and is another natural attenuation and redistribution pathway. In fact, phytoremediation of perchlorate has been proposed as a technology to remove perchlorate from contaminated soils and groundwater, particularly for shallow contamination.

According to a study, microorganisms have been shown to be capable of reducing perchlorate (Cl O−4) to chloride (Cl−) and oxygen, thus transforming perchlorate into harmless end-products. This study focused on microbial-mediated perchlorate reduction, and discusses issues of importance to the remediation of perchlorate contamination in groundwater.

Perchlorate disrupts one or more steps in the synthesis and secretion of thyroid hormones, resulting in subnormal levels of T4 and T3 and an associated compensatory increase in secretion of TSH. The perchlorate ion, because of its similarity to iodide in ionic size and charge, competes with iodide for uptake into the thyroid gland by the sodium-iodide symporter (NIS), a transport mechanism in the membranes of thyroid cells.

Perchlorates are released to the environment from a combination of human-made (anthropogenic) and natural sources. Perchlorate releases from accidents at manufacturing facilities and unsuccessful rocket launches, as well as activities related to the manufacture, disposal, or research of propellants, explosives, or pyrotechnics, are well documented.

The results from the sampling done by the USGS illustrated that most desert regions have either low/no detect or moderate concentrations of perchlorate in their groundwater with the exception of the Coachella Valley. Levels of perchlorate are due to perchlorate naturally occurring in groundwater. The concentrations found in groundwater are generally stable, or change slowly compared to organic constituents. It is not as critical to have an early warning groundwater contamination alert since perchlorate is naturally occurring.

The monitoring results showed perchlorate to be a widespread drinking water contaminant, occurring in several hundred wells, mostly in southern California. Domestic wells (used for private wells for household drinking water) were sampled and are included in these monitoring results. They are not regulated under the EPA. The homeowners are responsible for the water quality. Perchlorate has affected sources of drinking water (domestic wells) in both monitoring done by the CDPH.

Perchlorates are soluble in water and generally have high mobility in soils. This characteristic results in their ability to move from soil surfaces into groundwater (a process called leaching) when they enter the environment. Perchlorates are ionic substances and therefore, do not volatilize from water or soil surfaces. Perchlorates are known to remain unreacted in the environment for long periods of time. Perchlorates released to air will eventually settle out of the air, primarily in rainfall.

Perchlorates can enter the environment from several sources, both human-made (called anthropogenic) and natural sources. Since perchlorate is used in rockets and certain military applications, the manufacture, use, and disposal of products like rockets and missiles has led to perchlorate being released into the environment.

If the federal stand is to be lowered, costs will have to be justified. Compliance cost, new standard reduction and upgrading of public water systems will be needed if the standard is lowered significantly.

The main target organ for perchlorate toxicity in humans is the thyroid gland. Perchlorate has been shown to partially inhibit the thyroid’s uptake of iodine. Iodine is required as a building block for the synthesis of thyroid hormone. Thyroid hormones regulate certain body functions after they are released into the blood.

EPA has developed a Reference Dose (RfD) of 0.0007 mg/kg/day for perchlorate. The RfD is an estimate of a daily oral exposure to the human population (including sensitive subgroups) that is likely to be without appreciable risk of deleterious effects during a lifetime. This RfD leads to a drinking water equivalent level (DWEL) of 24.5 ppb.

Perchlorate naturally occurs in the environment and has been found in food and water. Perchlorate is introduced into the environment when rockets were made, tested, and disassembled and from fireworks, explosives, flares, and similar products. Perchlorate is also an impurity in certain industrial and consumer products, such a cleansers and bleaches, which also may result in its discharge to the environment.Perchlorate released to the environment is deposited in soil or water (rivers, streams, lakes, and ponds) and can leach into groundwater from soil. The main target organ for perchlorate toxicity in humans is the thyroid gland. Perchlorate inhibits the thyroid’s uptake of iodine. Iodine is required as a building block for the synthesis of thyroid hormone.

Perchlorates can enter the body after swallowing food or water contaminated with perchlorate. Since they easily dissolve in water, they quickly pass through the stomach and intestines and enter the bloodstream. Breathing in air containing dust or droplets of perchlorate, causes the particles to pass through the lungs and enter the bloodstream. It is unlikely for perchlorates to enter the body directly through the skin, but if present on your hands, hand-to-mouth-activity could contribute to oral exposure.

Perchlorate is not changed inside the body and the blood stream carries perchlorate to all parts of the body. A few internal organs (for example, the thyroid, breast tissue, and salivary glands) can take up relatively large amounts of perchlorate from the bloodstream. Perchlorate generally leaves these organs in a few hours. When perchlorate is swallowed, a small percentage is eliminated in the feces. More than 90% of perchlorate taken in by mouth enters the bloodstream. In the blood, perchlorate passes into the kidneys, which is then release into the urine. The body begins to clear itself of perchlorate through the kidneys within 10 minutes of exposure. Most of the perchlorate that is taken in to the body is quickly eliminated. Perchlorate can occur on the daily basis since it is present in many foods and in some drinking water sources.

California Department of Public Health (CDPH) has set the standard and action level to 6 µg/L.

Other states have taken a more stringent action level or standard since Federal EPA only has an interim action level and has not finalized a regulation for perchlorate. Perchlorate is an unregulated contaminant under the EPA.

According to a 2005 Journal of Environmental Science and Technology study using ion chromatography to find contaminants in agricultural products found quantifiable levels of perchlorate in 16 percent of conventionally produced lettuces and other leafy greens and in 32 percent of otherwise similar but organically produced samples.

Perchlorates have been shown to accumulate in the leaves of some food crops, tobacco plants, and more generally in broad leaf plants. As water transpires from the leaves, perchlorate remains behind in the leaf due to it in volatility under most environmental conditions. Although experimental studies detailing the environmental fate of perchlorates are limited, the current consensus indicates that they are persistent under most environmental conditions.

Whittaker-Bermite , Santa Clarita, CA

Besides its potential to cause endocrine system and reproductive problems, perchlorate is considered a “likely human carcinogen” by the U.S. Environmental Protection Agency (EPA).

Chesten Chong, Maryam Mortezai, Antonio Machado

Department of Environmental and Occupational Health, California State University, Northridge

The exposure and risk of perchlorate that are found in drinking water are extremely low. Unless taken in at high levels and exposed for a prolonged period of time, most of the perchlorate levels taken in by the human body are secreted through the urinary system. The greatest risks to high levels of perchlorate concentrations are sensitive individuals and those with nutrition deficiency. Perchlorate is found in food and water, but concentration levels are not high enough to cause adverse health effects in humans Alteration of diet or iodine supplements are not needed to reduce exposure to perchlorate. A healthy diet including fruits, vegetables and nutrient dense foods should be followed and the U.S. population consumes the adequate amounts of iodine.

Li Z, Li FX, Byrd D, et al.: Neonatal thyroxine level and perchlorate in drinking water. J Occup Environ Med 42:200-2005, 2000.Office of Environmental Health Hazard Assessment. March 11, 2004. Retrieved from http://www.oehha.org/public_info/facts/faqperchlorate.htmlOccupational, Safety and Health Administration. June 27, 1974. Retrieved from https://www.osha.gov/pls/oshaweb/owadisp.show_documentp_table=STANDARDS&p_id=9755#1910.109(a)(3)Perchlorate Information Bureau (2010). FAQ. February 19, 2014, from http://perchlorateinformationbureau.org/faq#q1.Roote, Diane S. "Technology Status Report, Perchlorate Treatment Technologies." 1st ed. Ground-Water Remediation Technologies Analysis Center, 2001Russel, C.G.; Robertson, A.; Chowdhury, Z.; McGuire, M.J. National cost implications of a perchlorate regulation. J. Amer. Water Work Assn. 2009, 101, 54-67.Scientific American. December 21, 2012. Retrieved from http://www.scientificamerican.com/article/perchlorate-in-drinking-water/.Smith, P.N.; Theodorakis, C.W.; Anderson, T.A.; Kendall, R.J. Preliminary assessment of perchlorate in ecological receptors at the Longhorn Army Ammunition Plant (LHAAP), Karnack, Texas. Ecotoxicology 2001, 10, 305-313.Soldin OP, Braverman LE, Lamm: Perchlorate clinical pharmacology and human health: A review. Therap Drug Monit 23:316-331, 2001.Srinivasan, R., & Sorial, G. (2009). Treatment of perchlorate in drinking water: A critical review. Separation and Purification Technology, 69(1), 7-21.United States Environmental Protection Agency. September 26, 2012. Retrieved from http://water.epa.gov/drink/contaminants/unregulated/perchlorate.cfmUnited States Environmental Protection Agency. May 2012. Retrieved from http://www.epa.gov/fedfac/pdf/technical_fact_sheet_perchlorate.pdfUnited States Department Of Health And Human Services. September 2008. Toxicological Profile for Perchlorates. Retrieved from http://www.atsdr.cdc.gov/toxprofiles/tp162.html. United States Food and Drug Administration. August 20, 2013. Retrieved from http://www.fda.gov/Food/FoodborneIllnessContaminants/ChemicalContaminants/ucm077572.htm#alterdiet

Agency for Toxic Substances and Disease Registry. September 2008. Retrieved from http://www.atsdr.cdc.gov/phs/phs.asp?id=892&tid=181Argus Research Laboratories, Inc. Oral (drinking water) developmental toxicity study of ammonium perchlorate in rabbits. Final Pilot Report; Argus Research Laboratories, Inc.: Warminster, PA, USA, 1998.Brown M. Gilbert, & Gu, Baohua (2006). The Chemistry of Perchlorate in the Environment. Retrieved from http://www.springer.com/978-0-387-31114-2. California Department of Public Health. February 26, 2014. Retrieved from http://www.cdph.ca.gov/certlic/drinkingwater/Pages/Perchlorate.aspxClewell RA, Merill EA, Narayanan L, et al.: Evidence for competitive inhibition iodide uptake by perchlorate and translocation of perchlorate into the thyroid. Intl J Toxicol 23:17-23, 2004.Crain, Michael,Cullison,Geoffrey D.,Flanagan,Susan J.P., Lathrop, Stephen, Siegel, Lenny, Trumpolt, Clayton W. Perchlorate: Sources, Uses, and Occurrences in the Environment. Wiley Periodicals, Inc., 2005. David C.,Herman, William T. Frankenberger: Microbial-Mediated Reduction of Perchlorate in Groundwater, Dep. of Soil and Environmental Sciences, Univ. of California, Riverside, CA 92521,1998,27,750-754.Dawson, Barbara J.M.; Belitz, Kenneth: Status of Groundwater Quality in the California Desert Region, 2006–2008: California GAMA Priority Basin Project. United States Geological Survey, 2013. Department of Toxic Substance Control. Retrieved from https://www.dtsc.ca.gov/LawsRegsPolicies/Regs/upload/HWMP_WS_dPerch-Sec6.pdf. EPA aims to limit perchlorate in water. (2011, Feb 02). Wall Street Journal (Online). Retrieved from http://search.proquest.com/docview/848725074?accountid= 7285.Frakenberger, William T. & Herman, David C. (1998). Microbial-Mediated Reduction of Perchlorate in Groundwater, Dep. of Soil and Environmental Sciences, Univ. of California, Riverside, CA. 92521,1998,27,750-754.Hammer J, Mark and Jr. Hammer J. Mark (2012). Water and Wastewater Technology (7 th edition).Upper Saddle River, NJ: Prentice Hall, Inc. Int J Environ Res Public Health. Apr 2009; 6(4): 1418–1442. Published online Apr 14, 2009. Doi:  10.3390/ijerph6041418.Klaassen, Curtis D. (2008). Casarett & Doull’s Toxicology: The Basic Science of Poisons (7th edition). Chicago, IL: Mcgraw-Hill Medical. Kimbrough, D.E.; Parekh, P. Occurrence and co-occurrence of perchlorate and nitrate in California drinking water sources. J. Amer. Water Work Assn. 2007, 99, 126-132.

Perchlorate is a relatively well-studied chemical due its pharmacological uses. The relatively low levels found in some wells and public water systems are unlikely to cause adverse effects in humans. Perchlorate is not a known carcinogen, does not accumulate in the body and is excreted from the body within hours.

Perchlorate treatment technologies may be generally classified into categories of destruction or removal technologies. Destructive processes include biological reduction, chemical reduction, and electrochemical reduction. Physical removal processes include anion exchange, membrane filtration (including reverse osmosis and nanofiltration), and electrodialysis, which all require subsequent disposal of removed perchlorate.

The limit of detection for perchlorate is between 0.01 ppb and 4ppb.

The highest level in the United States to date is 3,700,000 ppb, found in ground water near Las Vegas, Nevada.