SPOKANE RIVER-WASHINGTON STATE COMMON USE AREA SEDIMENT
CHARACTERIZATION: REVIEW OF THE DRAFT FIELD SAMPLING PLAN
SPOKANE, SPOKANE COUNTY, WASHINGTON
In general, the Draft Field Sampling Plan should allow for further characterization of metal
contamination along the Spokane River. DOH is concerned that sample collection procedures may
not sufficiently address all potential routes of exposure, including ingestion and dermal absorption.
In order to fully characterize potential human health risks, appropriate analytical techniques and
detection limits will be required. DOH is confident that once the recommended changes (as
described below) are considered, the Field Sampling Plan should provide a data set that will allow
for the determination of potential human health risks to users of the Spokane River.
This section will address specific comments and recommendations for changes to the Draft Field Sampling Plan for the Spokane River Common Use Area Sediment Characterization.2
- In section 2.1 it is stated that the "...focus of the risk assessment will be human exposure to beach sediments, primarily by ingestion,...." Since a large effort is being made to collect specific soil fractions that will adhere to skin, DOH would recommend that, in conjunction with ingestion, the dermal absorption pathway be considered as a primary focus for human exposure.
- Table 1 shows the common use sites selected for sampling. Previous versions of this table, specifically the table of preliminary sampling sites along the Spokane River (attachment A in the Field Sampling Plan), showed the priority ranking number (1-3) for each site. Showing a key for what the ranking number corresponds to would be extremely helpful. It is the understanding of DOH that many selection criteria (including accessability, use, child exposures) were used to pick these sites. It would be useful to know the criteria used for the inclusion of a site in the sampling plans. Either a column in the final table or a descriptive paragraph in the text of the sampling plan would be helpful.
- Please explain why only dry beach sediment samples are being collected. It is unclear as to why wet sediments, which may have differing contamination levels and absorption factors, are not being considered in this sampling plan.
- Please include the criteria used to categorize a sediment sample as 'dry.' Is this subjective or is a formal analytical procedure used? DOH is concerned that some of the collected samples may be damp or wet. The moisture content of soils can effect the dermal absorption of contaminants from the soils. Moisture content will impact the sieve size used to fractionate samples that are most easily dermally absorbed. Please explain how this issue will be addressed and controlled for.
- In section 5.2, the last sentence of the first paragraph states that "all sediment samples..will be sieved by the laboratory as per guidance from EPA (80-mesh) so that particles of the size expected to adhere to skin will be analyzed." This sentence is unclear. What portion will be analyzed? It is the assumption of DOH that the fraction that passes through the sieve will be further analyzed. Please clarify this sentence.
- Mark Stifelman, EPA, suggests adding statements that refer to using an 80-mesh sieve, which corresponds to 175 microns.4 One of the references noted by Mr. Stifelman (Kissel, Richter et al. 1996), states that "in dry soils, mass adherence appears to be predominately attributable to sub-150 µm.particles." Data presented in the paper also supports this conclusion.5 Please explain why a 175 micron sieve (80-mesh) was chosen instead of a 150 micron sieve (100-mesh).
- Collection of data that will allow for the assessment of human health risks through the ingestion route appears to be a main goal of the sampling. Please explain why only a sieved fraction is being collected. Contaminants present in a total sediment sample might provide a better representation of contaminants that children would be exposed to through ingestion (pica). Sieved samples are more representative for determining dermal exposures, but to address exposure through ingestion it is necessary to examine the total sample, not just a sieved portion. DOH recommends collecting total samples and conducting analysis of contaminants present in both the total sample and a sieved portion of the sample. Some total metal analysis will be conducted as part of the bank-deposit vertical profiling. The total metal analysis should be expanded.
- In section 6 please explain what is meant by northing and easting. Is this different from latitude and longitude values?
- Table 3, Anticipated Data Analyses, Rationale, and Methods, is unclear. Please clarify the sediment analyses. Will antimony, arsenic, cadmium, copper, lead, mercury, and zinc be analyzed in the total sample or just within a sieved fraction? Similarly, will grain size be determined for all sediments or just a sieved fraction? Exactly what type of analysis will be conducted on the 80-mesh sieve sediment sample? This is unclear from the table.
- In table 4, Data Quality Objectives, please explain what CLP and CRDL stand for. Please also clarify exactly which target detection limit will be used (risk based, background, or CRDL)? This is currently unclear. For arsenic, the Agency for Toxic Substances and Disease Registry (ATSDR) suggests using a health-based screening value for soil ingestion (pica) of 0.6 mg/kg to identify those contaminants in need of future evaluation.. Similarly for cadmium, ATSDR has set a health-based screening value at 0.4 mg/kg. For zinc, this health-based screening value is 600 mg/kg. DOH recommends that analytical techniques that will allow detection limits that are equal to, or below, these health-based values be used. The analytical methods must be sensitive enough to be useful as valid comparisons to health-based guidelines. Detection levels that are above these values will not allow DOH to adequately determine risks to human health.
- Please update Table 7, Project Schedule, to reflect the actual review period and field work dates.
- As additional information regarding this site becomes available, DOH would like the opportunity to conduct further evaluations. DOH would also like the opportunity to comment on future sampling and remedial work plans.
Office of Environmental Health Assessments
Washington State Department of Health
ATSDR Technical Project Officer
Division of Health Assessment and Consultation
Superfund Site Assessment Branch
- 1999 USGS Upper Spokane River Sediment Data, US. EPA, 1999.
- URS Greiner and CH2M Hill, Draft Field Sampling Plan for the Coeur D'Alene Basin-Wide RI/FS Addendum No. 15, Spokane River-Washington State Common Use Area Sediment Characterization, August 13, 1999.
- Spokane Regional Health District, Health Advisory for Heavy Metals in Upper Spokane River Sediments, July 12, 1999.
- US EPA, Mark Stifelman, Memorandum regarding Draft Spokane River Sampling: FSP-15, August 20, 1999.
- Kissel, J.C., Richter, K.Y., Fenske, R.A., Factors Affecting Soil Adherence to Skin in Hand-Press Trials. Bull. Environ. Contam. Toxicol. 56:722-728, 1996.