Date: November 6, 2014

To: Jeff Telander, EPA/OAQPS/SPPD

From: Gabrielle Raymond and Kristin Sroka, RTI International

Subject: Determination of “Non-Detect” Test Data for Clay Ceramics Proposed Rule

I. Introduction

In accordance with section 112 of the Clean Air Act (CAA), the U.S. Environmental 

Protection Agency (EPA) established national emission standards for hazardous air pollutants 

(NESHAP) on May 16, 2003 for the clay ceramics manufacturing industry, specifically the 

sanitaryware and ceramic tile industry sectors. Sanitaryware includes plumbing and bathroom 

fixtures such as toilets and sinks. Ceramic tile is used to cover floors and walls. The NESHAP 

regulated emissions of hydrogen fluoride (HF), hydrogen chloride (HCl), and particulate matter 

(PM)—a surrogate for hazardous air pollutant (HAP) metals—from new and reconstructed kilns 

located at clay ceramics facilities. On March 13, 2007, the D.C. Circuit Court vacated the 

emission standards for clay ceramics manufacturing due to issues associated with the 

methodology used to determine the minimum regulatory “floors” for new and existing units.1

Therefore, the EPA is proposing new standards for clay ceramics manufacturing, including 

standards for HF, HCl, mercury (Hg), non-Hg HAP metals (specifically, the PM surrogate), and 

dioxins/furans (D/F).

The list of affected sources to be regulated has been expanded to include new and 

existing kilns, spray dryers (ceramic tile only), press dryers (floor tile only), and spray glaze 

operations (sanitaryware and floor tile only). The facilities currently subject to the proposed 

NESHAP include all three sanitaryware facilities and one wall tile facility. The other ceramic tile 

facilities (all floor tile facilities) have taken the necessary steps to become synthetic area sources

(i.e., have obtained a federally enforceable limit reducing emissions below major source 

thresholds), and would not be subject to the major source clay ceramics NESHAP. The objective 

of this memorandum is to describe the determination of “non-detect” EPA Method 29 (multimetals) and EPA Method 23 (dioxin/furan) test data for evaluation in the setting of numeric 

MACT floor standards versus establishing work practice standards for the Clay Ceramics (CC)

Proposed Rule.

 1 Sierra Club v. EPA, 479 F.3d 875 (D.C. Cir. 2007).
2

II. Sources and Pollutants Evaluated

For CC kilns, the run flags for each HAP metal, including Hg, and each D/F toxic 

equivalent (TEQ)2 test run were evaluated to determine the “non-detect” status of the run. For 

CC glazing operations, the run flag for each HAP metal, including Hg, test run was evaluated to 

determine the “non-detect” status of the run. In addition, for CC dryers, each D/F TEQ run flag 

was evaluated to determine the “non-detect” status of the run. The guidelines from EPA’s 

memorandum Determination of “non-detect” from EPA Method 29 (multi-metals) and EPA 

Method 23 (dioxin/furan) test data when evaluating the setting of MACT floors versus 

establishing work practice standards (Johnson 2014) were followed for each evaluation.

III. Definitions from Guidance Memorandum (Johnson, 2014)

The following definitions appear in the Johnson guidance memorandum (2014) and also 

apply to this memorandum:

ADL (Above Detection Limit): Results from the lab show measured values above the 

MDL. (Be sure to distinguish reported values as being above the MDL versus above the RL or 

other lab ‘confidence’ level).

BDL (Below Detection Limit): A laboratory result where detectable amounts of an 

individual pollutant or congener are not found. Again, evaluate the data to ensure BDL means 

“below MDL” and not “below RL” or some other ‘confidence’ level.

DLL (Detection Limit Limited): A test result where some fractions of the analysis 

return detectable amounts of a pollutant or congener (above MDL), while other fractions are 

BDL.

EDL (Estimated Detection Limit): For Dioxin/Furan tests, a commonly reported 

estimate of the concentration where a given analyte would have to be present to produce a signal 

with a peak height of at least 2.5x the background noise signal level. The EDL determination is 

done for each sample set at the time of analysis. This is specific to the analytical technique and is 

affected by factors such as sample size, dilution, etc., commonly reported for non-detected 

analytes instead of other values such as PQL, RL, QL, etc. It is important to note that EDL and 

MDL are not the same, but EDL is a standard benchmark for determining detection from an 

isotope dilution analysis, common to dioxin/furan emission testing.

MDL (Method Detection Limit): Synonymous with the term LOD (Level of Detection) 

the MDL is defined as the lowest quantity of a substance that can be distinguished from the 

absence of that substance (i.e. a blank value) with a stated level of confidence. For the purposes 

of this document, the process of identifying the MDL of a given substance is defined in EPA 

Method 301, Section 15.

 2 For these runs, dioxin/furan emissions are expressed in terms of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxic 

equivalents (TEQ).
3

RDL (Representative Detection Limit): Sometimes referred to as the Representative 

Method Detection Limit (RMDL) this is the mean MDL value of a specific analyte determined 

by an MTG review of l lab analyses represented by labs who provided data for best performing 

sources, thereby creating a representative value by which to assess detection such that the best 

performing lab handing any particular analytical sample does not drive all detection limit 

discussion and decision making. By establishing this value as the mean of several labs we allow 

for the selection of local and cost effective analysis of environmental samples while maintaining 

a balance of quality analyses. The Westlin/Merrill memorandum defines RDL for dioxin/furans 

as EDL x 2 (Westlin and Merrill, 2011).

IV. Run Flags

Run flags are determined by the facility/analytical laboratory for each run. They compare 

each analytical fraction mass to the MDL or other detection limit values (e.g., Reporting Limit) 

as available. Mercury runs have five analytical fractions and the other HAP metals have two 

analytical fractions. The run flag is BDL if all of the fraction masses are below the MDL, DLL 

if one or more of fraction masses are below the MDL, and ADL if all of the fraction masses are 

above the MDL. Similarly, for dioxin/furan testing, there are multiple congeners for each TEQ 

run. The run flag is BDL if all of the congener masses are below the MDL; DLL if one or more 

congeners are below the MDL; and ADL if all the congeners are above the MDL. For each 

fraction/congener mass that is below the MDL, the MDL mass is used for the fraction/congener 

mass and subsequent emissions calculations.

V. Mercury

For each kiln and glazing operation with Hg test data, each run flag was evaluated to 

determine the “non-detect” status of the run, according to Johnson (2014). If the run flag was 

ADL or DLL, the run was considered ADL. If the run flag was BDL, the run mass (sum of five

fraction masses, as available) was evaluated and compared to the RDL value provided in the 

guidance document Data and procedure for handling below detection level data in analyzing 

various pollutant emissions databases for MACT and RTR emissions limits (Westlin and Merrill, 

2011) for Hg analyzed by Cold Vapor AA, 0.56 μg. If the run mass was less than the RDL, the 

run was considered BDL. If the run mass was greater than the RDL and was based on MDL 

values, the run was considered BDL. If the run mass was greater than the RDL and was based 

on other detection limit values (e.g., Reporting Limit), the data was set aside and not used for the 

analysis. (Note that data set aside for this analysis were not set aside for actual MACT floor 

rankings and floor calculations.) The following figure displays the steps in determining the 

“non-detect” status of a run for this analysis based on the guidance provided by Johnson (2014).
4

Figure 1. Steps in determining the “non-detect” status of test run data for setting MACT 

floors.

Table 1 displays the percentage of ADL and BDL runs for Hg from CC kilns and glazing 

operations. The run-by-run data used to calculate the percent ADL and BDL for Hg from CC 

kilns and glazing operations can be found in Appendix A.
5

Table 1. Percent ADL and BDL for Hg from CC Kilns and Glazing Operations

Hg

Floor tile 

roller kilns

Wall tile 

roller kilns

Tile glaze 

lines

First-fire 

sanitaryware 

tunnel kilns

Total Runs 15 6 9 18

No. Set Aside 0 0 0 0

No. Used 15 6 9 100

No. BDL 0 0 0 0

No. ADL 15 6 9 18

% BDL 0 0 0 0

% ADL 100 100 100 100

The percent BDL for CC kilns and glazing operations was 0 percent; as such, the EPA is 

proposing MACT floor standards for Hg for CC floor tile roller kilns, wall tile roller kilns, tile 

glaze lines and first-fire sanitaryware tunnel kilns.

VI. Non-Hg HAP Metals

For each kiln and glazing operation with non-Hg HAP metals test data, each run flag was 

evaluated to determine the “non-detect” status of the run, according to Johnson (2014). If the run 

flag was ADL or DLL, the run was considered ADL. If the run flag was BDL, the run mass 

(sum of each fraction mass) was evaluated and compared to the RDL value provided in the 

guidance document (Westlin and Merrill, 2011) for each individual non-Hg HAP metal analyzed 

by either Inductively Coupled Plasma/Mass Spectrometry or Graphite Furnace Atomic 

Absorption Analysis [ICP/MS or GFAAA] or Inductively Coupled Atomic Emission 

Spectroscopy or Atomic Absorption Analysis [ICP/AES or AA]. Table 2 presents the RDL 

values for each non-Hg HAP metal for each analytical method.

Table 2. RDL values for each Non-Hg HAP Metal per Analytical Method (Westlin and 

Merrill, 2011)

Method 29 Non-Hg 

HAP Metals

ICP/AES or AA

RDL (μg)

ICP/MS or GFAA

RDL (μg)

Antimony 1.2E+01 1.1E+00

Arsenic 1.9E+01 4.0E-01

Beryllium 1.1E-01 8.0E-02

Cadmium 1.5E+00 3.0E-02

Chromium 2.5E+00 3.0E-01

Cobalt 2.5E+00 3.0E-01

Lead 1.5E+01 3.0E-01

Manganese 7.0E-01 3.0E-01

Nickel 5.4E+00 5.4E+00

Selenium 2.7E+01 8.0E-01
6

If the run mass was less than the RDL, the run was considered BDL. If the run mass was 

greater than the RDL and was based on MDL values, the run was considered BDL. If the run 

mass was greater than the RDL and was based on other detection limit values (e.g., Reporting 

Limit), the data was set aside and not used for the analysis. (Note that data set aside for this 

analysis were not set aside for actual MACT floor rankings and floor calculations.) Table 3

displays the percentage of ADL and BDL runs for each non-Hg HAP metal from CC kilns and 

glazing operations. The run-by-run data used to calculate the percent ADL and BDL for each 

non-Hg HAP metal from CC kilns and glazing operations can be found in Appendix B.
7

Table 3. Percent ADL and BDL for Each Non-Hg HAP Metal from CC Kilns and Glazing 

Operationsa

Source Sb As Be Cd Cr Co Pb Mn Ni Se

Total NonHg HAP 

Metals

Total Runs Floor tile 

roller kilns

15 15 15 15 15 15 15 7 15 15 142

No. Set Aside 0 0 9 0 0 0 0 0 0 0 9

No. Used 15 15 6 15 15 15 15 7 15 15 133

No. BDL 0 0 0 0 0 0 0 0 0 0 0

No. ADL 15 15 6 15 15 15 15 7 15 15 133

% BDL 0 0 0 0 0 0 0 0 0 0 0

% ADL 100 100 100 100 100 100 100 100 100 100 100

Total Runs Wall tile 

roller kilns

6 6 6 6 6 6 6 4 6 6 58

No. Set Aside 0 0 6 0 0 0 0 0 0 0 6

No. Used 6 6 0 6 6 6 6 4 6 6 52

No. BDL 0 0 0 0 0 0 0 0 0 0

No. ADL 6 6 6 6 6 6 4 6 6 52

% BDL 0 0 0 0 0 0 0 0 0 0

% ADL 100 100 100 100 100 100 100 100 100 100

Total Runs Tile glaze 

lines

9 9 9 9 9 9 9 6 9 9 87

No. Set Aside 0 7 9 4 0 0 0 0 0 4 24

No. Used 9 2 0 5 9 9 9 6 9 5 63

No. BDL 4 0 0 0 4 0 0 0 0 8

No. ADL 5 2 5 9 5 9 6 9 5 55

% BDL 44 0 0 0 44 0 0 0 0 13

% ADL 56 100 100 100 56 100 100 100 100 87

Total Runs First-fire 

sanitaryware 

tunnel kilns

18 18 18 18 18 18 18 16 18 18 178

No. Set Aside 0 2 18 0 0 0 0 0 0 1 21

No. Used 18 16 0 18 18 18 18 16 18 17 157

No. BDL 0 0 0 0 0 0 0 0 0 0

No. ADL 18 16 18 18 18 18 16 18 17 157

% BDL 0 0 0 0 0 0 0 0 0 0

% ADL 100 100 100 100 100 100 100 100 100 100

a Sb = antimony; As = arsenic; Be = beryllium; Cd = cadmium; Cr = chromium; Co = cobalt; Pb = lead; Mn = 

manganese; Ni = nickel; Se = selenium.

The majority of the individual non-Hg HAP metals had a high percentage of runs above 

detection level, thus not meeting the criteria for a work practice standard. As a result, the EPA is 

proposing MACT floor standards for PM as a surrogate for non-Hg HAP metals for CC floor tile 

roller kilns, wall tile roller kilns, tile glaze lines and first-fire sanitaryware tunnel kilns.
8

VII. Dioxin/Furan (TEQ)

Seventeen specific dioxin/furan congeners are considered in the calculation of TEQ 

values. For the 17 specific dioxin/furan congeners, the mass reported in the laboratory analysis 

of the test report was multiplied by the 2005 World Health Organization (WHO) toxic equivalent 

factors (TEF) to calculate the TEQ value for each run. If the mass for the congener was flagged 

as BDL, then a value of zero was used as the mass. The mass of each of the 17 calculated TEQ 

values were summed together to get a total TEQ mass for each run.

The total TEQ mass for each run was compared to the Utilities TEQ EDL, 0.018 ng

(Westlin and Merrill, 2011). If the total TEQ mass was greater than the EDL, the run was 

considered ADL. If the total TEQ mass was less than the EDL, the run was considered BDL.

Table 4 summarizes the overall percentage of ADL and BDL runs for TEQ from CC 

kilns and dryers. The run-by-run data used to calculate the overall percent ADL and BDL for 

TEQ from CC kilns and dryers can be found in Appendix C.

Table 4. Percent ADL and BDL for TEQ from CC Kilns and Dryers

Source No. Runs % ADL % BDL

Floor tile roller kilns 15 100 0

Floor tile press dryers 12 58 42

Floor tile spray dryers 15 73 27

Wall tile roller kilns 6 50 50

Wall tile press dryers 3 0 100

Wall tile spray dryers 3 100 0

First-fire sanitaryware tunnel kilns

[8 stacks, 5 kilns] 24 75 25

Sanitaryware ware dryers

[5 stacks, 3 dryers] 15 0 100

The percent BDL for floor tile roller kilns, floor tile press dryers, floor tile spray dryers, 

wall tile roller kilns, wall tile spray dryers, and first-fire sanitaryware tunnel kilns was not 

significant; thus, the EPA is proposing MACT floor standards for dioxins/furans (TEQ) for these 

sources.

The percent BDL for wall tile press dryers and sanitaryware ware dryers was 100 percent;

thus, the EPA is proposing no limit for dioxins/furans (TEQ) for these two sources.
9

VIII. References

Johnson, S. 2014. Determination of “non-detect” from EPA Method 29 (multi-metals) and EPA 

Method 23 (dioxin/furan) test data when evaluating the setting of MACT floors versus 

establishing work practice standards. Memorandum from Steffan Johnson, SPPD, MPG, to 

SPPD management and MACT rule writers. June 5, 2014.

Westlin, P., and R. Merrill. 2011. Data and procedure for handling below detection level data 

in analyzing various pollutant emissions databases for MACT and RTR emissions limits. 

Memorandum from Peter Westlin, SPPD, MPG and Raymond Merrill, AQAD, MTG, to 

SPPD management and MACT rule writers. December 13, 2011.
Appendix A

CC Hg Data
A-1

The run-by-run data used to calculate the percent ADL and BDL for Hg from CC kilns and 

glazing operations are provided in the corresponding Appendix A Microsoft Excel® file

 
Appendix B

CC Non-Hg HAP Metal Data
B-1

The run-by-run data used to calculate the percent ADL and BDL for non-Hg HAP metals from 

CC kilns and glazing operations are provided in the corresponding Appendix B Microsoft 

Excel® file.
Appendix C

CC TEQ Data
C-1

The run-by-run data used to calculate the percent ADL and BDL for TEQ from CC kilns and 

dryers are provided in the corresponding Appendix C Microsoft Excel® file.