This memorandum presents an exposure evaluation of metals sampling data for newly manufactured CalStar Coal Fly Ash (CFA) bricks, performed in support of the first phase of a product exposure assessment. Toxicity Characteristic Leaching Procedure (TCLP) and Synthetic Precipitation Leaching Procedure (SPLP) results were evaluated to determine the leaching potential of CFA trace metals from fly ash bricks, and surface wipe sample results were evaluated to assess the potential for dermal and oral ingestion exposures (via hand-to-mouth contact) to CFA trace metals from direct skin contact with exterior bricks. Based on Gradient’s evaluation of the sampling results, the presence of CFA metals in newly manufactured CalStar bricks is not expected to result in any exposures of health concern via dermal contact with brick surfaces or via leaching. Additional details regarding Gradient’s exposure evaluation are provided below.
1 Sample Collection and Analysis
Newly manufactured brick halves were collected by CalStar on 6/22/2009 and were sent to two laboratories for analysis. ACZ Laboratories (Steamboat Springs, CO) performed TCLP and SPLP extractions and subsequent metals analysis. Torrent Laboratories, Inc. (Milipitas, CA) performed sampling and metals analysis of brick sample wipes.
2 Quality Control Review
Prior to interpreting the sampling data, Gradient reviewed the quality control (QC) results associated with the brick sample analyses to determine whether any data quality issues would affect the validity of the reported data (note that raw data were not yet made available and thus were not reviewed). Our evaluation included a review of QC summary results for initial and continuing calibration verification samples (ICVs and CCVs) and blanks (ICBs and CCBs), method blanks, laboratory control samples (LCS), analysis duplicates, matrix spike/matrix spike duplicates, ICP serial dilutions, etc. Based on the QC review, we determined that in general, the brick sample analyses were in control and the reported data were considered usable. Note that some of the data results were qualified during the QC review; for example, some of the antimony, arsenic, copper, selenium, and zinc wipe sample results, SPLP lead results, and TCLP nickel and zinc results were re-assigned as nondetects (qualified U) due to method blank contamination.
3 Data Evaluation
3.1 Surface Wipe Samples
Torrent Laboratories, Inc. reported wipe sampling results in micrograms of metal per wipe (µg/wipe) and brick dimensions in mm (length, width, height, and hole diameter). Gradient calculated the surface area of each brick according to Equation 1, below. We then divided the laboratory results in μg/wipe by the surface area sampled in order to determine the surface wipe loading in micrograms of metal per square meter (μg/m2):
Surface Area = 2(LW+LH+WH) – 4π(D/2)² (Equation 1)
L=Length H=Height
W=Width D=Hole Diameter
Once the surface wipe loading was determined, Gradient calculated the minimum, maximum, and mean wipe sample results, as well as the coefficient of variability (CV) for each metal. Nondetected results were replaced with one half of the reporting limit in order to calculate summary statistics. The associated summary statistics are shown in Table 1. As shown in Table 1, many of the metals of toxicological concern (e.g., arsenic, beryllium, cadmium, selenium, thallium) were not detected in any surface wipe samples despite the use of highly sensitive analytical methods. Other metals (e.g., barium, chromium, cobalt, lead, mercury, molybdenum, nickel, silver, vanadium) were consistently detected, with relatively low sample-to-sample variability (as reflected in the calculated CV values).
To assess the potential health significance of the surface wipe results, we compared detected values (and values equal to one-half the reporting limit for the metals that were not detected) to the World Trade Center (WTC) health-based settled dust screening values (COPC Committee, 2003). These screening values, which are based on conservative (i.e., health protective) exposure assumptions (e.g., every day exposures of young children over extended periods of time) and toxicological values, were developed by US EPA and other members of the Contaminants of Potential Concern (COPC) Committee of the World Trade Center Indoor Air Task Force Working Group to support residential cleanup efforts in Lower Manhattan following the World Trade Center catastrophe. They were developed to be protective of potential exposures associated with ingestion and dermal contact with contaminants in dust residues on indoor surfaces, and due to the incorporation of several assumptions specific to indoor exposure conditions (e.g., exposure times of 4 hours/day for hard surfaces), represent highly conservative comparison criteria for exterior surfaces. Given that US EPA accounted for the dissipation of contaminant surface loadings in dust (which is expected for dust borne contaminants, when there is not an active contaminant source, due to a combination of cleaning, resuspension, dilution, and volatilization) in the development of the WTC screening values, we also provide in Table 1 modified WTC screening values where there is no consideration of dissipation. These modified WTC screening levels are approximately 60% less than the published WTC screening values, and are considered to be more appropriate for comparison with the brick surface wipes where metals surface loadings are not expected to diminish with time in the same manner.
Table 1 shows that all surface wipe results are well-below the WTC settled dust screening values (both with and without dissipation), indicating that regular dermal contact with newly manufactured CalStar fly ash bricks is not expected to result in any exposures of health concern.
Table 1: Summary of Wipe Sample Results (μg/m)
| Analyte | N | N Detected |
Minimum | Maximum | Average | CV | WTC Screening Level | WTC Screening Level Without Dissipation |
|---|---|---|---|---|---|---|---|---|
| Antimony | 5 | 0 | 12 | 18 | 15 | 0.16 | 627 | 261 |
| Arsenic | 5 | 0 | 16 | 23 | 15 | 0.15 | 387 | 163 |
| Barium | 5 | 5 | 2263 | 5377 | 4092 | 0.29 | 109,752 | 45,760 |
| Beryllium | 5 | 0 | 3 | 3 | 3 | 0.03 | 3,136 | 1,307 |
| Cadmium | 5 | 0 | 3 | 3 | 3 | 0.03 | 1,557 | 649 |
| Chromium | 5 | 5 | 35 | 78 | 57 | 0.29 | 4,704 | 1,961 |
| Chromium, Hexavalent | 5 | 5 | 14 | 74 | 33 | 0.76 | 4,704 | 1,961 |
| Cobalt | 5 | 5 | 14 | 44 | 31 | 0.35 | 31,358 | 13,074 |
| Copper | 5 | 0 | 60 | 107 | 85 | 0.25 | 62,716 | 26,149 |
| Lead | 5 | 5 | 13 | 34 | 25 | 0.32 | 270 | NA |
| Mercury | 5 | 5 | 1 | 3 | 2 | 0.35 | 157 | 65 |
| Molybdenum | 5 | 3 | 3 | 9 | 5 | 0.43 | NA | NA |
| Nickel | 5 | 5 | 25 | 81 | 52 | 0.39 | 31,358 | 13,074 |
| Selenium | 5 | 0 | 48 | 61 | 54 | 0.10 | 7,839 | 3,269 |
| Silver | 5 | 5 | 8 | 22 | 16 | 0.37 | 7,839 | 3,269 |
| Thallium | 5 | 0 | 3 | 3 | 3 | 0.03 | 110 | 46 |
| Vanadium | 5 | 5 | 83 | 208 | 156 | 0.31 | 10,975 | 4,576 |
| Zinc | 5 | 0 | 1039 | 2060 | 1458 | 0.33 | 470,366 | 196,116 |
3.2 TCLP and SPLP Analyses
ACZ Laboratories, Inc. reported the SPLP results in milligrams of metal per liter (mg/L). Gradient calculated the minimum, maximum, and mean SPLP results as well as the coefficient of variation (CV) for each metal. Nondetected results were replaced with one half of the method detection limit in order to calculate summary statistics. The summary statistics are shown in Table 2. For comparison, US EPA National Drinking Water Standards4, including both primary (health-based) and secondary (based on aesthetic, cosmetic, or technical effects) standards, are also shown in Table 2.
Table 2: Summary of SPLP Results (mg/L)
| Analyte | N | N Detected |
Minimum | Maximum | Average | CV | US EPA Drinking Water Standard |
|---|---|---|---|---|---|---|---|
| Aluminum | 5 | 5 | 20.1 | 23.6 | 21.84 | 0.070 | 0.05 to 0.2 |
| Antimony | 5 | 5 | 0.00070 | 0.0012 | 0.00090 | 0.22 | 0.006 |
| Arsenic | 5 | 2 | 0.00025 | 0.0006 | 0.00037 | 0.45 | 0.01 |
| Barium | 5 | 5 | 0.52 | 0.741 | 0.6184 | 0.17 | 2 |
| Beryllium | 5 | 0 | 0.00005 | 0.00005 | 0.00005 | 0 | 0.004 |
| Cadmium | 5 | 0 | 0.00005 | 0.00005 | 0.00005 | 0 | 0.005 |
| Chromium | 5 | 5 | 0.07 | 0.0979 | 0.080 | 0.16 | 0.1 |
| Cobalt | 5 | 5 | 0.00033 | 0.00037 | 0.00034 | 0.049 | NA |
| Copper | 5 | 0 | 0.0015 | 0.0015 | 0.0015 | 0.0 | 1.3 |
| Iron | 5 | 2 | 0.0100 | 0.060 | 0.024 | 0.91 | 0.3 |
| Lead | 5 | 0 | 0.00005 | 0.00030 | 0.00017 | 0.57 | 0.015 |
| Manganese | 5 | 0 | 0.0003 | 0.00025 | 0.00025 | 0 | 0.05 |
| Mercury | 5 | 0 | 0.0001 | 0.0001 | 0.0001 | 0 | 0.002 |
| Molybdenum | 5 | 5 | 0.017 | 0.028 | 0.023 | 0.18 | NA |
| Nickel | 5 | 0 | 0.0003 | 0.0003 | 0.0003 | 0 | NA |
| Selenium | 5 | 5 | 0.013 | 0.015 | 0.014 | 0.062 | 0.05 |
| Silver | 5 | 0 | 0.0000 | 0.000025 | 0.000025 | 0 | 0.1 |
| Thallium | 5 | 0 | 0.0001 | 0.00005 | 0.00005 | 0 | 0.002 |
| Vanadium | 5 | 5 | 0.020 | 0.029 | 0.024 | 0.16 | NA |
| Zinc | 5 | 0 | 0.005 | 0.005 | 0.005 | 0 | 5 |
ACZ Laboratories, Inc. also reported TCLP results in milligrams of metal per liter (mg/L). Gradient calculated the minimum, maximum, and mean TCLP result as well as the CV for each metal. Nondetected results were replaced with one half of the method detection limit in order to calculate summary statistics. These summary statistics are shown in Table 3. For comparison, the US EPA TCLP regulatory levels are also shown in Table 3.
Table 3: Summary of TCLP Results (mg/L)
| Analyte | N | N Detected |
Minimum | Maximum | Average | CV | TCLP Regulatory Level |
|---|---|---|---|---|---|---|---|
| Aluminum | 5 | 5 | 0.3 | 19.3 | 6.5 | 1.194 | NA |
| Antimony | 5 | 4 | 0.0010 | 0.0030 | 0.0022 | 0.38 | NA |
| Arsenic | 5 | 0 | 0.0015 | 0.0015 | 0.0015 | 0 | 5 |
| Barium | 5 | 5 | 0.8 | 1.7 | 1.1 | 0.329 | 100 |
| Beryllium | 5 | 0 | 0.00025 | 0.00025 | 0.00025 | 0 | NA |
| Cadmium | 5 | 0 | 0.00025 | 0.00025 | 0.00025 | 0 | 1 |
| Chromium | 5 | 5 | 0.10 | 0.12 | 0.11 | 0.063 | 5 |
| Cobalt | 5 | 5 | 0.0015 | 0.0020 | 0.0017 | 0.122 | NA |
| Copper | 5 | 0 | 0.0015 | 0.0015 | 0.0015 | 0 | NA |
| Iron | 5 | 0 | 0.01 | 0.01 | 0.01 | 0 | NA |
| Lead | 5 | 0 | 0.00025 | 0.00025 | 0.00025 | 0 | 5 |
| Manganese | 5 | 1 | 0.0015 | 0.004 | 0.002 | 0.559 | NA |
| Mercury | 5 | 0 | 0.0001 | 0.0001 | 0.0001 | 0 | 0.2 |
| Molybdenum | 5 | 5 | 0.030 | 0.036 | 0.033 | 0.069 | NA |
| Nickel | 5 | 0 | 0.0015 | 0.006 | 0.0024 | 0.839 | NA |
| Selenium | 5 | 5 | 0.023 | 0.030 | 0.026 | 0.1 | 1 |
| Silver | 5 | 0 | 0.00015 | 0.00015 | 0.00015 | 0 | 5 |
| Thallium | 5 | 5 | 0.0012 | 0.0019 | 0.0015 | 0.187 | NA |
| Vanadium | 5 | 5 | 0.012 | 0.032 | 0.020 | 0.38 | NA |
| Zinc | 5 | 0 | 0.005 | 0.01 | 0.007 | 0.391 | NA |
With the exception of aluminum in SPLP leachate, SPLP and TCLP results for each metal are below the respective comparison criteria, namely the US EPA National Drinking Water Standards and the US EPA TCLP regulatory levels. The SPLP results for aluminum exceed the secondary maximum contaminant level (MCL) range of 0.05 to 0.2 mg/L, but it is important to note that this secondary MCL is not health-based and instead is based on color changes. As a result, its exceedance does not indicate a potential exposure of health concern.6 Therefore, based on the fact that no SPLP or TCLP leachate samples show exceedances of either the primary (i.e., health-based) drinking water standards or the TCLP regulatory levels, we conclude that the leaching of metals from newly manufactured CFA bricks is not expected to result in exposures of health concern.
References
Gradient. 2009. Coal Fly Ash (CFA) Brick Sampling and Analysis Plan, Product Safety Testing/Exposure Evaluation Study. Prepared for CalStar Cement. June 8.
World Trade Center Indoor Air Task Force Working Group, Contaminants of Potential Concern (COPC) Committee. 2003. “World Trade Center indoor environmental assessment: Selecting contaminants of potential concern and setting health-based benchmarks.” 78p. May.