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