DRAFT PRIVILEGED AND CONFIDENTIAL 

memo_072809 

20 University Road, Cambridge, MA 02138 • (617) 395-5000 • Facsimile (617) 395-5001 • www.gradientcorp.com

Memorandum

To: Julie Rapoport, CalStar Date: July 28, 2009 

From: Kim Reynolds Reid 

Maggie Pollock 

Chris Long 

Subject: Metals Exposure Evaluation - Newly Manufactured

CalStar Coal Fly Ash (CFA) Bricks 

 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.1

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 

 

1 As described in Gradient's Sampling and Analysis Plan (Gradient, 2009), both new and "aged" CFA brick samples will be 

evaluated by Gradient. The "aged" brick halves are currently being subjected to freeze-thaw testing according to ASTM Standard

C 67. When the freeze-thaw testing is complete in 2-3 months, the "aged" brick halves will also undergo metals testing, at which 

time Gradient will perform a similar exposure evaluation as presented herein. A final report summarizing all of the results will 

be prepared for CalStar at this time. 
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memo_072809 2 Gradient CORPORATION

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.2

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 

 

2

 Details regarding Gradient's QC review will be presented in the final report submitted to CalStar. 
DRAFT PRIVILEGED AND CONFIDENTIAL 

memo_072809 3 Gradient CORPORATION

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.3

 

 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/m2

) 

Analyte N N 

Detected 

Minimum Maximum Average CV WTC Screening 

Level[1]

WTC Screening Level

Without Dissipation 

Antimony 5 0 12 18 15 0.16 627 261 

Arsenic 5 0 16 23 21 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 

Notes: 

Nondetects were replaced with 0.5×Reporting Limit (RL). Note that in cases where the sample result was considered nondetected and 

qualified (U) due to blank contamination, the RL was raised to the concentration detected in the sample. 

CV=coefficient of variation, NA=Not Available 

[1] World Trade Center Indoor Air Task Force Working Group, Contaminants of Potential Concern (COPC) Committee. May 2003. "World 

Trade Center indoor environmental assessment: Selecting contaminants of potential concern and setting health-based benchmarks.".

 

3

 Note that there may be some reduction in surface metal loadings in the bricks over time due to washing away of metals in 

rainwater, and for some metals (e.g., mercury) via volatilization. As a result, comparison with the modified WTC screening 

values may add to the conservatism in the evaluation of the surface wipe sampling results. Note that potential exposures 

associated with the washing away of metals over time from the bricks are addressed by the TCLP and SPLP leaching protocols 

for the newly manufactured and freeze-thaw bricks (see Section 3.2 below for the TCLP and SPLP results for the newly 

manufactured bricks). 
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memo_072809 4 Gradient CORPORATION

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* 

Notes: 

Nondetects were replaced with 0.5×Method Detection Limit (MDL). Note that in cases where the sample result was 

considered nondetected and qualified (U) due to blank contamination, the MDL was raised to the concentration 

detected in the sample. 

CV=coefficient of variation. 

* denotes secondary drinking water standard. All other values are primary drinking water standards. See 

http://www.epa.gov/safewater/contaminants/index.html 

NA=Not Available.

 

4

 Available at the US EPA website: http://www.epa.gov/safewater/contaminants/index.html 
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memo_072809 5 Gradient CORPORATION

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 35

. 

Table 3 

Summary of TCLP Results (mg/L) 

Analyte N N 

Detected 

Minimum Maximum Average CV TCLP Regulatory 

Level[1]

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 

Notes: 

Nondetects were replaced with 0.5×Method Detection Limit (MDL). Note that in cases where the sample result was 

considered nondetected and qualified (U) due to blank contamination, the MDL was raised to the concentration 

detected in the sample. 

CV=coefficient of variation. 

NA=Not Available 

[1] See 40 CFR 264.24 

 

5

 The TCLP limits are found in 40 CFR 264.21, downloaded at 

http://frwebgate.access.gpo.gov/cgi-bin/get-cfr.cgi?TITLE=40&PART=261&SECTION=24&TYPE=TEXT. 
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memo_072809 6 Gradient CORPORATION

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. 

 

6

 Importantly, secondary MCLs are not enforced by US EPA and are only provided as guidelines for public water systems to 

assist them in their management of drinking water supplies for aesthetic considerations, such as taste, color, and odor. As such, 

they are not highly relevant for this exposure evaluation. 
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memo_072809 7 Gradient CORPORATION

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.