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State of New Jersey Department of Environmental Protection
State of New Jersey Department of Environmental Protection

Sub-Groups

Analytical Chemistry Subgroup:

Certified Method: The Site Remediation Program has been accepting analytical results for hexavalent chromium using a non-DEP certified analytical method for Cr(VI) digestion. There is an EPA-certified method available (Method 3060a). Should the Department mandate use of the EPA method for hexavalent chromium determinations? What should the Department do about data obtained by the non-certified method the Site Remediation Program has been using for site decisions?

Data Review and Acceptance: What should the Department policy be on analytical data where the associated quality assurance protocols are outside method limits?

Additional Analytical Methods: EPA Method 6800 “Elemental and Speciated Isotope Dilution Mass Spectrometry” is approved and included in SW846 for the analysis of speciated metals, including chromium. The Office of Quality Assurance (OQA) does not currently offer certification for EPA Method 6800. Should the OQA offer certification for EPA Method 6800? If so, what should be the extent of its potential applications?

Method Deficiencies: There is a question that the methods for the regulatory-approved methods of preparation and analysis of hexavelent chromium (EPA Methods 3060a, 7196a and 7199) underestimate its in-situ concentration in certain types of soil. What are the circumstances where the low bias in hexavalent chromium measurements exist? Are there any conditions under which high bias (resulting from oxidation of Cr(III) to Cr(VI)) in sample preparation and/or measurement occurs?

Quality Assurance Tools: The Department has proposed a collaboration with EPA, National Institute of Standards and Technology (NIST) and the Environmental and Occupational Health Sciences Institute (EOHSI) to develop a reference material of defined Cr(VI) concentration using a source material from Hudson County, New Jersey that can be used to assess the efficacy of future Cr(VI) measurements. Should such a reference material be developed?

Other Measurement Options: Is it possible to develop a commercially available, DEP-certifiable method to replace the current method (Method 3060a)? If not, should speciation of hexavalent chromium continue to be performed should only total chromium be measured? Are there any known biases to the measurement of total chromium in soil that would prevent its use in establishing Cr remediation standards?

Environmental Chemistry Subgroup

Concentration effect: “Blooms” of concentrated hexavalent chromium have been observed on soils and in structures at the sites. Soluble hexavalent chromium dissolves in ground water and can move throughout the soil column. The chromium becomes concentrated as the water evaporates. Rainfall events and movement of groundwater levels can change the location of these concentrated evaporative fronts. Can the concentration of chromium in the blooms be anticipated and modeled? Is there a concentration in the soil that protects against elevated levels of hexavalent chromium from being deposited in this way?

Interconversion: What is the capacity of trivalent chromium to convert to hexavalent chromium in the soil of the chromate ore processing residue sites? Do the current remediation standards adequately account for this interconversion? If not, recommend some options the Department should pursue to address any discrepancy or inadequacy, including research.

Nature of COPR: The interconversion question is imbedded in the larger problem of the nature of chromite ore processing residue (COPR). The physical (micropore) structure of chromite ore processing residue may be the rate limiting factor in the release of hexavalent chromium. What is the nature of this waste material and how does it influence what we know about chromium chemistry?

Transport to Groundwater: What concentration of chromium in the soil at the chromate ore processing residue sites results in chromium levels above the drinking water standard in ground water? Do the current clean up standards adequately protect ground water?

Risk Assessment Subgroup

Carcinogenicity via ingestion: Do toxicological studies show that hexavalent chromium is carcinogenic when ingested? Should the exposure route be altered to address potential ingestion carcinogenicity?

Contact Dermatitis: The procedure for site specific allergic contact dermatitis criteria includes the assumption that exposure to hexavalent chromium occurs in solution because the approved threshold is solution-based. If this is not appropriate, suggest another mechanism, and a method for quantifying dose-response and exposure.

Exposure Pathways: Are the exposure pathways for chromium adequately addressed in the soil standards, particularly as they relate to alternate remediation standards?

Air & Dust Transport Subgroup

Exposure Pathways: The protocol for the development of alternate remediation standards for chromium needs to include the physical mechanism by which dust gets into the air and reach humans via inhalation. Are the mechanisms for this transport adequately calculated?

Return to Chromium Workgroup - Home

 

Office of Science
Dr. Gary A. Buchanan, Manager

Mailing Address:
Mail code 428-01, P.O. Box 420
P.O. Box 420
Trenton, NJ 0862
Office Location:
428 East State St., 1st floor
Trenton, NJ 08625
Phone: (609) 984-6070
Fax: (609) 292-7340


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P. O. Box 402
Trenton, NJ 08625-0402

Last Updated: November 1, 2010