Emerging Science Supporting the 2005 National Research Council Perchlorate Risk Assessment
John P. Gibbs, Kerr-McGee Shared Services LLC, Oklahoma City, OK

Effect of Varying Toxicity Values on Perchlorate Risk Assessment Results
Ishrat S. Chaudhuri, ENSR International, Westford, MA

Update on DoD Perchlorate Treatment Technology Development
Bryan Harre, Naval Facilities Engineering Service Center, Port Hueneme, CA

Perchlorate Treatment Using Bioreactors: Current Applications and Future Prospects
Paul B. Hatzinger, Shaw Environmental, Inc., Lawrenceville, NJ

In Situ Bioremediation of Perchlorate and 1,1,1-Trichloroethane using Emulsified Edible Oil Substrate (EOS®)
Christie Zawtocki, Solutions Industrial & Environmental Services, Inc., Raleigh, NC

Perchlorate Regulation in the State of Massachusetts

Paul W. Locke, Massachusetts Department of Environmental Protection, Bureau of Waste Site Cleanup, One Winter Street, Boston, MA 02176, Tel: 617-566-1160, Fax: 617-292-5530, Email: Paul.Locke@state.ma.us

In 2001, the first instance of Perchlorate contamination in Massachusetts was identified in groundwater plumes emanating from the Massachusetts Military Reservation on Cape Cod.  Since then the Massachusetts Department of Environmental Protection (DEP) has invested significant resources and effort to determine the presence and identify the sources of Perchlorate in drinking water supplies Statewide and to evaluate the health risks of Perchlorate as new information and research becomes available.

In February 2004 DEP issued a drinking water health advisory of 1 µg/L for Perchlorate, consistent with EPA's actions resulting from its January 2002 Perchlorate health assessment document.  DEP also initiated the processes to establish a drinking water maximum contaminant limit (MCL) for Perchlorate and hazardous waste cleanup standard.  In March 2004, DEP promulgated regulations requiring all public water supplies to test for Perchlorate.  Also, in the fall of 2004, DEP promulgated draft revisions to the State's hazardous waste cleanup regulations that included a proposed groundwater cleanup standard of 1 µg/L in areas protected for current or future drinking water use.

DEP and its Science Advisory Committee reviewed the January 2005 National Academy of Sciences Report on Perchlorate and other recent information before proposing a drinking water standard and resubmitting its disposal site cleanup standards in Spring 2005. 

This presentation summarizes the road the Commonwealth has taken to regulate perchlorate in both its Drinking Water and Waste Site Cleanup Programs.

Emerging Science Supporting the 2005 National Research Council Perchlorate Risk Assessment

John P. Gibbs, M.D, FACOEM, Medical Director and Vice President, Health Management Division, Kerr-McGee Shared Services LLC, P.O. Box 25861, Oklahoma City, OK 73125
(Copyright National Ground Water Association, 2005)

In sufficient amounts, perchlorate can inhibit iodine uptake by the thyroid, ultimately leading to diminished thyroid function.  Recent studies in Europe and the United States have determined that maternal hypothyroidism during pregnancy, even when mild and considered subclinical, may be associated with impairment of normal brain development and intelligence in offspring. Concern about the possibility that iodine uptake inhibition from environmental perchlorate could result in impaired maternal thyroid function during pregnancy and adverse neurodevelopmental effects in the fetus, has led to proposed a proposed reference dose (RfD) as low as 0.00003 mg/kg-day.  For 18 months during 2003 and 2004, a committee of the National Research Council (NRC) reviewed the science available in order to assess the risk of perchlorate ingestion.  In the committee’s January 2005 report, it concluded that the no-observed-adverse-effect level (NOAEL) is 0.4 mg/kg-day and that the no-observed-effect-level (NOEL) is 0.007 mg/kg-day.  Based on the NOEL, the committee recommended an RfD of 0.0007 mg/kg-day.  Subsequent to the NRC committee deliberations, five new scientific studies have been completed that strongly support the committee’s NOAEL and NOEL and support that the recommended RfD is safe for even the most susceptible populations – fetuses of pregnant women with insufficient iodine consumption

Effect of Varying Toxicity Values on Perchlorate Risk Assessment Results

Ishrat S. Chaudhuri, ENSR International, 2 Technology Park Drive, Westford, MA 01886, Email: ichaudhuri@ensr.com
Julie AF Kabel, ENSR International, 2 Technology Park Drive, Westford, MA 01886, Email: ichaudhuri@ensr.com

Perchlorate has been used as a solid rocket propellant and ignitable source in munitions.  It is a public health issue of recent interest because it has been found at low levels in the drinking water used by millions of Americans.  The main toxicological effect of this chemical is to limit the uptake of iodide by the thyroid gland.  This reduction of iodide uptake, in turn, can eventually disrupt thyroid hormones that regulate metabolism and growth.  There are various toxicology studies on perchlorate that have been used by Agency and other toxicologists to develop toxicity values that can then be used to calculate safe concentrations of this chemical in soil and water.  These include animal toxicology studies, controlled studies in human volunteers, and epidemiological studies.  The use of a specific study and interpretation of the results can result in widely differing toxicity estimates, which result in turn in differing safe concentrations.  For example, California’s public health goal of 6 ppb is based on a human study where adult volunteers were fed daily amounts of perchlorate.  In contrast, a recent paper by Strawson et. al. (2004)¹ developed a toxicity value from the same study used by California, which would result in a drinking water goal of 98 ppb.  The recent study by the National Academy of Sciences developed a Reference Dose that was 20-fold higher than a previous interim Reference Dose developed by U.S. EPA.  Development of site-specific cleanup goals for perchlorate can similarly differ based on which toxicity value is used to develop the cleanup goal.  Based on this diversity of toxicological opinion and risk assessment approaches, it is important when conducting a perchlorate risk assessment to consider the full range of toxicity values and understand the uncertainty in these values.  This presentation summarizes the pertinent toxicological literature, and discusses the range of toxicity values and uncertainties associated with perchlorate risk assessment.

¹Strawson J., Q. Zhao and M. Dourson. 2004. Reference dose for perchlorate based on thyroid homone change in pregnant women as the critical effect. Regulatory Toxicology and Pharmacology, 39:44-65.

Update on DoD Perchlorate Treatment Technology Development

Bryan Harre, Naval Facilities Engineering Service Center, 1100 23^rd Avenue, Port Hueneme, CA 93043, Tel: 805-982-1795, Fax: 805-982-4304, Email: bryan.harre@navy.mil
Erica Becvar, AFCEE/TDE, 3300 Sidney Brooks, Brooks City-Base, TX 78235, Tel: 210-536-4314, Fax: 210-536-5989, Email: erica.becvar@brooks.af.mil

Since perchlorate was discovered in water supplies in California, Nevada, and Arizona, much progress has been made in developing treatment methods capable of removing perchlorate from water. Most of the DoD’s perchlorate treatment technology efforts have been directed at two technologies: biological treatment and ion exchange. In the biological treatment process, microbes destroy perchlorate by converting the perchlorate ion to oxygen and chloride. In most cases, nutrients must be added to sustain the microbes. In ion exchange the perchlorate ion is replaced by chloride, a chemically similar to the perchlorate ion.  Bench-, pilot-, and full-scale studies have demonstrated that ion exchange systems can reliably reduce perchlorate concentrations.  This presentation will review the efforts of the DoD to develop treatment technologies for perchlorate over the last ten years and highlight the most recent developments.

Perchlorate Treatment Using Bioreactors: Current Applications and Future Prospects

Paul B. Hatzinger, Ph.D., Shaw Environmental, Inc., 17 Princess Road, Lawrenceville, NJ  08648, Tel: 609-895-5356, Fax: 609-895-1858, Email: Paul.hatzinger@shawgrp.com    
A. Paul Togna, Ph.D., Shaw Environmental, Inc., 17 Princess Road, Lawrenceville, NJ  08648, Tel: 609-895-5375, Fax: 609-895-1858, Email: Paul.togna@shawgrp.com
William J. Guarini, M. E., Shaw Environmental, Inc., 17 Princess Road, Lawrenceville, NJ  08648, Tel: 609-895-5384, Fax: 609-895-1858, Email: William.guarini@shawgrp.com

Bioremediation is proving to be a versatile and economical approach for treating perchlorate-contaminated water.  During the past decade, a variety of different bioreactor designs have been pilot-tested for perchlorate treatment, and seven full-scale systems have been constructed.  Five fluidized bed reactor systems (FBRs) currently treat more than 9 million gallons per day of perchlorate-contaminated groundwater, with influent concentrations ranging from < 1 mg/L to greater than 250 mg/L.  Perchlorate in the effluent water from each of these systems is consistently below 4 mg/L, the practical quantitation limit for EPA Method 300.0.  In addition to groundwater treatment, two continuous stirred tank reactors (CSTRs) are presently removing perchlorate from military and industrial wastewaters at influent concentrations as high as 5,000 mg/L.  Future prospects for bioreactors include the treatment of perchlorate-contaminated drinking water and the removal of residual perchlorate from salt brines generated during water treatment by regenerable ion exchange.   Field tests have been conducted to evaluate the effectiveness of packed bed reactors (PBRs) and FBRs for treatment of potable water. These tests have resulted in both technologies receiving a preliminary approval for this application from the California Department of Health Services.  Membrane bioreactors (MBRs) are being tested in the laboratory for a variety of applications, including drinking water, wastewater, and brine treatment.  An overview of the design, operating parameters, and performance of the different bioreactor reactor systems will be presented.

In Situ Bioremediation of Perchlorate and 1,1,1-Trichloroethane Using Emulsified Edible Oil Substrate (EOS^®). 

Christie Zawtocki, P.E., Solutions Industrial & Environmental Services, Inc., 3722 Benson Drive, Raleigh, NC 27609, Tel: 919- 873-1060, Fax: 919- 873-1074, Email: czawtocki@solutions-ies.com
M. Tony Lieberman, RSM, Solutions Industrial & Environmental Services, Inc., 3722 Benson Drive, Raleigh, NC 27609, Tel: 919- 873-1060, Fax: 919- 873-1074, Email:  tlieberman@solutions-ies.com
Dr. Robert C. Borden, P.E., Solutions Industrial & Environmental Services, Inc., 3722 Benson Drive, Raleigh, NC 27609, Tel: 919- 873-1060, Fax: 919- 873-1074, Email:  rcborden@solutions-ies.com

Studies have shown that microorganisms from a wide variety of aquifers can anaerobically biodegrade perchlorate when supplied with appropriate organic substrates and related amendments.  1,1,1-Trichloroethane (1,1,1-TCA) can also be anaerobically degraded; however, the biological remediation of this compound in actual groundwater plumes is less well documented.  Solutions-IES, with funding from the Environmental Security Technology Certification Program (ESTCP), has been evaluating the effectiveness of emulsified edible oil substrate for promoting anaerobic biodegradation of these compounds in a commingled plume at a rocket manufacturing facility in Maryland.  The shallow aquifer at the site contains elevated concentrations of perchlorate and 1,1,1-TCA released from a closed lagoon.  Based on laboratory studies that compared several potential biodegradable long-term substrates, Solutions-IES selected EOS^® for the field trial.  In October 2003, a 60-foot long permeable reactive biobarrier (PRBB) was created perpendicular to the direction of groundwater flow by injecting approximately 850 pounds of EOS^® into a 10-foot thick zone.  The EOS^® served as a carbon source for cell growth and an electron donor for energy generation, supporting long-term anaerobic biodegradation of the target contaminants. 

Routine performance monitoring demonstrated the effectiveness of the PRBB and the longevity of the EOS^®.  Geochemical parameters confirmed that EOS^® created conditions favorable for anaerobic biodegradation within and downgradient of the barrier.  Perchlorate concentrations entering the barrier at 10,000 mg/L were reduced to BDL within four days of contact.  1,1,1-TCA concentrations (~23,000 mg/L) decreased initially due to sorption to the oil emulsion, but subsequent monitoring showed reductive dechlorination of 1,1,1-TCA to 1,1-dichloroethane and chloroethane with eventual conversion to non-toxic end products.  Over one year after EOS^® injection, the barrier continued to perform well with no evidence of flow bypassing and continuing evidence of residual substrate in the aquifer.

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