EP A 600/R-12/703 July 2012 | ww w

.epa.g o v/o rd



# Removal of Peruorocarboxylic Acids (PFCAs) from Carpets Treated with

Stain-protection Products by Using Carpet Cleaning Machines

c

e of Rese arch a n d Deve lop ment

### EPA/600/R-12/703

July 2012



# Removal of Perfluorocarboxylic Acids (PFCAs) from

Carpets Treated with Stain-protection Products by

Using Carpet Cleaning Machines

Heidi F. Hubbard 1 

### , Zhishi Guo 2 

### , and Kenneth A. Krebs

U.S. Environmental Protection Agency

Office of Research and Development

National Risk Management Research Laboratory

Air Pollution Prevention and Control Division

Research Triangle Park, NC 27711

and

Sara K. Metzger, Corey A. Mocka, Robert H. Pope, and Nancy F. Roache

ARCADIS US, Inc.

4915 Prospectus Dr., Suite F

Durham, NC 27713

1 Current address: ICF International, 2222 East NC-54, Suite 480, Durham, NC 27713

2 Corresponding author (guo.zhishi@epa.gov)

## Notice

This document has been reviewed in accordance with the U.S. Environmental Protection Agency

policy and approved for publication. Mention of trade names or commercial products does not

constitute endorsement or recommendation for use.

1

## Executive Summary

E.1 Background and Objective

Perfluorinated carboxylic acids (PFCAs) are fully fluorinated organofluorine compounds with a

carboxylic acid functional group (-COOH). As a member of the PFCA family, perfluorooctanoic

acid (PFOA) and its salts were once used as a surfactant in the manufacturing of perfluorinated

polymers such as polytetrafluoroethylene (PTFE). Thus, PFOA and its salts may exist as residuals

in PFTE or other fluoropolymer products. PFOA and other PFCAs may also exist in fluorotelomer

products (such as stain-repellants) as unwanted reaction by-products. The U.S. Environmental

Protection Agency (EPA) began investigating PFOA and its related chemicals in the 1990s and

found that it is very persistent in the environment, is found at low levels both in the environment

and in the blood of the general U.S. population, and causes developmental and other adverse

effects in laboratory animals (U.S. EPA, 2012). In 2006, EPA and the eight major companies in the

fluoropolymer and fluorotelomer industry launched the PFOA Stewardship Program, in which

companies committed to reduce global facility emissions and product content of PFOA and related

chemicals by 95 percent by 2010 and to work toward eliminating emissions and product content by

2015 (U.S. EPA, 2012).

Previous studies have shown that consumer articles that are made from or treated with

fluoropolymers and fluorotelomers products may contain low levels of PFCAs. PFCAs are found

in a variety of consumer products, including, but not limited to, treated clothing and textiles, floor

care products, paper containers for food, and carpets. Among the consumer articles examined by

Washburn et al. (2005) and Guo et al. (2009), carpet that was pretreated with stain-repellents and

carpet that was treated with after-market stain-resistant formulations were the largest PFOA

sources in homes. Once PFCAs are brought into the indoor environment, they are expected to stay

for a long period of time because PFCAs are persistent in the environment and because most

PFCAs are semi-volatile compounds. PFCAs can also be absorbed by household dust, which may

serve as a source for inhalation or digestive exposure. Therefore, it is important to understand the

feasibility of in-situ removal of PFCAs from treated carpet. To our knowledge, this issue has not

been addressed by any publications in the existing literature.

The main goal of this study was to quantify the efficiency of common carpet cleaning methods

― steam cleaning and hot water extraction

― in the removal of PFCAs from residential and

commercial carpet that was manually treated with stain-protection solutions. The objective was to

determine if these cleaning techniques are viable methods for reducing indoor exposure to PFCAs

associated with carpet that was previously treated with PFCA-containing products.

2

### E.2 Test Method

E.2.1 Test Facility

The carpet cleaning experiments were performed under close-to-realistic conditions in the U.S.

EPA research house located in Cary, NC. The research house is a three-bedroom, ranch-style house

with a crawl space, a central, forced-air heating system that uses natural gas, and an electric airconditioning system. The total floor area is 126 m 2 

### . The master bedroom (MB) and front-corner

bedroom (FCBR) were used for the carpet cleaning tests.

E.2.2 Test Materials

Carpet

By the time this project started, mill-treated carpet containing high levels of PFCAs were no longer

available in local stores, an indication that the manufacturers had taken actions to reduce or

eliminated PFCAs from their products. In this study, two types of carpet with low-levels of

background PFCAs were treated with after-market carpet treatment solutions (see below). The two

types of carpet were: 1) residential carpet that was Green-Label Certified by the Carpet and Rug

Institute (CRI) with a pile yarn content of 100% polytrimethylene terephthalate (PTT) – a product

from recycled plastic bottles – with a textured cut pile and a woven polypropylene backing, and 2)

commercial carpet made with Antron® fiber, a nylon 6,6, hollow-filament fiber with a soilresistant treatment incorporated into the fiber. This type of commercial carpet is commonly used in

schools and offices. The PFCA content in these carpets were below 8 ng/g. These background

PFCAs may have come from recycled old carpet.

Carpet Treatment Solutions

Two commercial carpet stain-protection treatments (CT-1 and CT-2) were used to treat the carpet.

The total PFCA contents in these treatment solutions are presented in Section E.3.1 below.

Carpet Cleaning Machines

Two carpet cleaning machines were chosen to clean the carpets after treatment with a carpet stainprotection solution: 1) a residential cleaning machine (CM-1), the Rug Doctor Mighty Pro model

MP C-20, and 2) a portable professional steam cleaner (CM-2), the Century 400 Ninja Warrior.

The residential unit uses hot tap water for the extraction with no additional heating during the

cleaning process; the professional steam cleaner has an 1850-watt, in-line heater that produces

steam. Figure E.1 shows the Rug Doctor (front) and the Ninja Warrior (rear).

3E.1. Residential and commercial carpet cleaning machines used for the tests

Carpet Cleaning Detergent



### Two carpet cleaning agents were selected to test the removal of PFCAs from carpets, i.e., a

residential carpet cleaning detergent (CD-2) recommended for use with the residential machine

(CM-1) and a commercial carpet cleaning detergent (CD-1) chosen for use with the commercial

machine (CM-2). According to the material safety data sheets (MSDSs), CD-1 contains 3 to 6% of

dipropylene glycol methyl ether (CAS# 34590-94-8) while CD-2 contains 1 to 5% of sodium 2­

ethylhexyl sulfate (CAS# 126-92-1) and <1% of branched tridecylalcohol (CAS# 69011-36-5).

Prior to use, each clean agent was screened for PFCAs. The residential detergent measured most

PFCAs below the quantification limits of the instrument, with perfluorotridecanoic acid (C 13 

### )

having the highest concentration at 3 ng/mL. The commercial detergent had only trace levels of C 8 

### through C 10 

### , and all were below the practical quantification limits.

E.2.3 Test Procedure

The test carpet was installed on a solid urethane carpet pad on the bedroom floors. Prior to the

application of the carpet treatment solution, carpet samples were taken to determine the PFCA

content in untreated carpet. The carpet was then treated with a carpet treatment solution.

Following the application of the treatment and a subsequent 48-hour drying period, a series of three

carpet cleanings was performed. A drying period of at least 48 hours followed each cleaning before

carpet samples were collected. The first set of tests used only hot water or steam for the cleaning

process to determine the efficiency of each carpet cleaning machine’s method of removing the

applied PFCAs. Additionally, four experiments, one of which was a duplicate test, were conducted

using cleaning detergents (CD-1 or CD-2) in conjunction with a carpet cleaning machine to assess

any additional PFCA removal. The complete experimental test matrix is summarized in Table E.1.

4Table E.1. Experimental matrix for testing of carpet care treatments

Experiment Carpet Type Carpet Treatment

(CT) Cleaning

Machine (CM) Carpet

Detergent (CD)

1 Commercial CT-1 CM-2 None

2 Commercial CT-2 CM-2 None

3 a Residential CT-1 CM-1 None

4 Residential CT-1 CM-2 None

5 Residential CT-2 CM-2 None

6 Commercial CT-2 CM-2 CD-1

7 Residential CT-1 CM-1 CD-2

8 b Residential CT-1 CM-1 CD-2

9 Residential CT-2 CM-2 CD-1

a Initial scouting test; b Duplicate test.



### E.3 Findings

E.3.1 Extractable PFCAs in Carpet Treatment Solutions

The total extractable PFCAs (i.e., the sum of all PFCAs quantified) in the two carpet treatment

solutions were, respectively, 6360 and 7500 ng/g. The distributions of individual PFCAs are shown

in Figure E.2. The error bars represent ±1 standard deviation (n = 4 for CT-1 and n = 6 for CT-2).

50 500 1000 1500 2000 2500Concentration (ng/g) 

### CT-1

CT-2

Figure E.2 PFCA contents in the two carpet treatment solutions (CT-1 and CT-2)



### E.3.2 PFCA Content in Carpet Before and After Cleaning

As an example, Figure E.3 shows the general patterns of the carpet cleaning tests. The application

of the carpet treatment solution increased the PFCA content in the carpet and, following each

carpet cleaning event, there was reduction of PFCA content in the carpet. In this experiment, the

total reduction after three rounds of cleaning was approximately 50%.

60 500 1000 1500 2000 2500 3000

Pre-Application Post-Application Post-Cleaning

Round 1 Post-Cleaning

Round 2 Post-Cleaning

Round 3Concentration (ng PFCAs / g carpet)

Figure E.3 Average total PFCAs in composite carpet fiber samples for Experiment 4

[Residential carpet treated with carpet treatment solution CT-1; hot-water extraction with the residential

cleaning machine (CM-1); no detergent]



### E.3.3 Percent Removal of PFCAs by Carpet Cleaning

For each experiment, the percent removal of total PFCAs after the final cleaning was calculated by

comparison of the total PFCA concentration after application of the carpet treatment to the total

PFCA concentration after the third round of cleaning. As shown in Figure E.4, the percent removal

of the total PFCA ranged from 26% to 76% with an average of 55%.

7100%

80%

60%

40%

20%

0%



### Experiment IDTotal Percent Removal

1 2 3 4 5 6 7 8 9

Figure E.4. Percent removal of total PFCAs following three rounds of cleaning for each experiment



### E.3.4 Effect of Cleaning Machine

The two types of cleaning machines yielded similar removal efficiency for total PFCAs. The

difference shown in Table E.2 is not statistically significant.

Table E.2 Comparison of the removal efficiency of the two cleaning machines for total PFCAs

following three rounds of cleaning

ID Machine Type Cleanin g Method Mean SD n

CM-1 Residential Hot-water extraction 52.2% 6.2% 3

CM-2 Commercial Steam cleaning 57.4% 18.5% 4



### E.3.5 Effect of Detergent

Using detergent during carpet cleaning showed modest increase in removal efficiency (Figure E.5).

However, comparison of the test with detergent CD-1 with the test without using any detergent

yielded the two-tailed P value of 0.1063. By conventional criteria, this difference is considered to

be not statistically significant.

8% Removal 100%

80%

60%

40%

20%

0%�

CD-1 CD-2 None�

Detergent

Figure E.5 Effect of using carpet detergent on the average removal efficiency for total PFCAs

following three rounds of cleaning



### E.4 Resear ch Implications

The average American home has about 1000 square feet (93 m 2 

### ) of carpet. Previous research has

shown that treated carpets represent one of the largest sources of PFCAs in homes. Additionally,

PFCAs are highly stable, with the potential for a long residence time indoors, and can also bind to

house dust, making it difficult to remove the PFCAs from the indoor environment. The results of

this research indicated that cleaning carpets can reduce the amount of PFCAs they contain, but the

chemicals cannot be totally eliminated by the cleaning process. Carpet cleaning by hot-water or

steam cleaning is only modestly effective in removing PFCAs. On average, the removal efficiency

for each round of cleaning is approximately 20%. At this removal efficiency, it requires three,

seven, and ten rounds of cleaning to remove, respectively, 50%, 80%, and 90% of total PFCAs in

treated carpet.

9

## Table of Contents

Notice

.................................................................................................................................................... 1

Executive Summary

............................................................................................................................ 2

Table of Contents

.............................................................................................................................. 10

List of Figures

.................................................................................................................................... 12

List of Tables

...................................................................................................................................... 13

Acronyms and Abbreviations

.......................................................................................................... 15

1. Introduction

................................................................................................................................. 16

1.1 Background

................................................................................................................................... 16

1.2 Goal and Objective

....................................................................................................................... 17



### 2. Materials and Methods

............................................................................................................... 18

2.1 Test Facility

................................................................................................................................... 18

2.2 Test Materials

................................................................................................................................ 19

2.2.1 Carpet Selection for Research House Experiments

......................................................... 19

2.2.2 Professional Carpet Treatment Solutions

........................................................................ 19

2.2.3 Carpet Cleaning Machines

............................................................................................... 20

2.2.4 Carpet Cleaning Detergents

............................................................................................. 21

2.3 Experimental Design

.................................................................................................................... 21

2.4 Test Procedure

.............................................................................................................................. 22

2.4.1 Layout of Carpet Sampling Sections

............................................................................... 22

2.4.2 Dilution and Application of the Carpet Treatment

.......................................................... 23

2.4.3 Cleaning of Carpets

.......................................................................................................... 25

2.5 Sampling Methods

........................................................................................................................ 26

2.5.1 Collection of Carpet Samples

.......................................................................................... 26

2.5.2 Wipe Sampling

................................................................................................................. 27

2.6 Sample Analysis

........................................................................................................................... 28

2.6.1 Extraction of Residential Carpet Samples

....................................................................... 28

2.6.2 Extraction of Commercial Carpet Samples

..................................................................... 28

2.6.3 Extraction of Liquid Samples

.......................................................................................... 29

2.6.4 QC Sample Preparation

.................................................................................................... 29

2.6.5 Sample Analysis

............................................................................................................... 29

2.7 Quality Assurance and Quality Control

....................................................................................... 30



### 102.7.1 Uniformity of Carpet Protector Treatment Solution

....................................................... 31

2.7.2 Calibration of LC/MS/MS

............................................................................................... 32

2.7.3 Daily Calibration Checks

................................................................................................. 33

2.7.4 Contamination Checks

..................................................................................................... 33

2.7.5 Weight Measurements

...................................................................................................... 33



### 3. Results

........................................................................................................................................... 34

3.1 Summary of Experimental Conditions

......................................................................................... 34

3.2 Extractable PFCA Content in Carpet Treatment Solutions

......................................................... 34

3.3 Extractable PFCA Content in Wipe Samples Taken from the Walls

.......................................... 35

3.4 Extractable PFCA Content in Carpet Samples

............................................................................ 36

3.5 Percent Removal of PFCAs by Cleaning

..................................................................................... 41



### 4. Discussion

..................................................................................................................................... 43

4.1 Removal Efficiency of Speciated Extractable PFCAs in Carpet Samples

.................................. 43

4.2 Overall PFCA Removal Efficiency

.............................................................................................. 43

4.3 Comparison of Duplicate Experiments

........................................................................................ 44

4.4 Factors Affecting the Efficiency of PFCA Removal

................................................................... 44

4.5 Composite vs. Individual Samples

............................................................................................... 46

4.6 Extractable PFCA Content Collected from Walls

....................................................................... 46



### 5. Conclusions and Recommendations

......................................................................................... 47

Acknowledgments

............................................................................................................................. 48

References

.......................................................................................................................................... 49

Appendix A : Data .............................................................................................................................A1

11

## List of Figures

Figure 2.1. Floor plan for the research house in Cary, NC

............................................................................... 18

Figure 2.2. Residential and commercial carpet cleaning machines

.................................................................. 20

Figure 2.3. Diagram of generic carpet sampling quadrant

................................................................................ 23

Figure 2.4. Application cart

............................................................................................................................... 24

Figure 2.5. Diagram of first application process

............................................................................................... 24

Figure 2.6. Diagram of second application process

.......................................................................................... 25

Figure 2.7. Diagram of carpet cleaning using commercial cleaner CM-2 (not to scale)

................................. 26

Figure 2.8. Residential carpet after all sampling stages

.................................................................................... 27

Figure 2.9. Average of individual quadrant samples for post-application PFCA concentrations in

each experiment and associated standard deviations

..................................................................... 32

Figure 3.1. Extractable PFCA content in carpet treatment solutions CT-1 and CT-2

..................................... 35

Figure 3.2. Average total PFCAs in composite carpet fiber samples for Experiment 1 (C-1-2-0)

................. 37

Figure 3.3. Average total PFCAs in composite carpet fiber samples for Experiment 2 (C-2-1-0)

................. 37

Figure 3.4. Average total PFCAs in composite carpet fiber samples for Experiment 3 (R-1-1-0)

................. 38

Figure 3.5. Average total PFCAs in composite carpet fiber samples for Experiment 4 (R-1-2-0)

................. 38

Figure 3.6. Average total PFCAs in composite carpet fiber samples for Experiment 5 (R-2-2-0)

................. 39

Figure 3.7. Average total PFCAs in composite carpet fiber samples for Experiment 6 (C-2-2-1)

................. 39

Figure 3.8. Average total PFCAs in composite carpet fiber samples for Experiment 7 (R-1-1-2)

................. 40

Figure 3.9. Average total PFCAs in composite carpet fiber samples for Experiment 8 (R-1-1-2),

duplicate of Experiment 7

............................................................................................................... 40

Figure 3.10. Average total PFCAs in composite carpet fiber samples for Experiment 9 (R-2-2-1)

............... 41

Figure 3.11. Calculated percent removal of total PFCAs for each experiment

................................................ 42

Figure 4.1. Average percent reduction in PFCAs by experimental variable for composite samples

............. 45



### 12

## List of Tables

Table 2.1. Conditions in the research house......................................................................................................19

Table 2.2. Components of carpet treatments CT-1 and CT-2...........................................................................20

Table 2.3. Experimental matrix for testing of carpet care treatments ..............................................................22

Table 2.4. Carpet fiber collection strategy ........................................................................................................27

Table 2.5. Analyte names, abbreviations, chemical formulas, molecular weights (g/mol), and

Chemical Abstracts Service registration numbers (CAS #) ..........................................................30

Table 2.6. Measurement quality objectives.......................................................................................................31

Table 3.1. Environmental parameters recorded during the cleaning experiments...........................................34

Table 3.2. Results of wall wipe samples collected during Experiment 3.........................................................36

Table 4.1. Percent removal efficiency of speciated compounds ......................................................................43

Table 4.2. Composite carpet sample data summarizing average percent reduction in PFCAs by

experiment.......................................................................................................................................44

Table 4.3. Average percent reduction in PFCAs by experimental variable for composite samples ..............45

Table A.1. Average extractable PFCAs (ng/g) and percent of original amount removed in composite

carpet fiber samples at each experimental stage for Experiment 1 (C-1-2-0)..............................A2

Table A.2. Average extractable PFCAs (ng/g) and percent of original amount removed in composite

carpet fiber samples at each experimental stage for Experiment 2 (C-2-2-0)..............................A3

Table A.3. Average extractable PFCAs (ng/g) and percent of original amount removed in composite

carpet fiber samples at each experimental stage for Experiment 3 (R-1-1-0)..............................A4

Table A.4. Average extractable PFCAs (ng/g) and percent of original amount removed in composite

carpet fiber samples at each experimental stage for Experiment 4 (R-1-2-0)..............................A5

Table A.5. Average extractable PFCAs (ng/g) and percent of original amount removed in composite

carpet fiber samples at each experimental stage for Experiment 5 (R-2-2-0)..............................A6

Table A.6. Average extractable PFCAs (ng/g) and percent of original amount removed in composite

carpet fiber samples at each experimental stage for Experiment 6 (C-2-2-1). Re-use of

carpet from Experiment 2..............................................................................................................A7

Table A.7. Average extractable PFCAs (ng/g) and percent of original amount removed in composite

carpet fiber samples at each experimental stage for Experiment 7 (R-1-1-2).

Experiments 7 and 8 considered replicate tests. ...........................................................................A8

Table A.8. Average extractable PFCAs (ng/g) and percent of original amount removed in composite

carpet fiber samples at each experimental stage for Experiment 8 (R-1-1-2).

Experiments 7 and 8 considered replicate tests. ...........................................................................A9

Table A.9. Average extractable PFCAs (ng/g) and percent of original amount removed in composite

carpet fiber samples at each experimental stage for Experiment 9 (R-2-2-1). Re-use of

carpet from Experiment 5............................................................................................................A10

Table A.10. Average extractable PFCAs (ng/g) post-application in individual carpet fiber samples

for Experiment 1 (C-1-2-0). ........................................................................................................A11



### 13Table A.11. Average extractable PFCAs (ng/g) post-application in individual carpet fiber samples

for Experiment 2 (C-2-2-0). ........................................................................................................A11

Table A.12. Average extractable PFCAs (ng/g) post-application in individual carpet fiber samples

for Experiment 3 (R-1-1-0). ........................................................................................................A12

Table A.13. Average extractable PFCAs (ng/g) post-application in individual carpet fiber samples

for Experiment 4 (R-1-2-0). ........................................................................................................A12

Table A.14. Average extractable PFCAs (ng/g) post-application in individual carpet fiber samples

for Experiment 5 (R-2-2-0). ........................................................................................................A13

Table A.15. Average extractable PFCAs (ng/g) post-application in individual carpet fiber samples

for Experiment 6 (C-2-2-1). ........................................................................................................A13

Table A.16. Average extractable PFCAs (ng/g) post-application in individual carpet fiber samples

for Experiment 7 (R-1-1-2). Experiments 7 and 8 considered replicate tests............................A14

Table A.17. Average extractable PFCAs (ng/g) post-application in individual carpet fiber samples

for Experiment 8 (R-1-1-2). Experiments 7 and 8 considered replicate tests............................A14

Table A.18. Average extractable PFCAs (ng/g) post-application in individual carpet fiber samples

for Experiment 9 (R-2-2-1). ........................................................................................................A15



### 14

## Acronyms and Abbreviations

AOC Articles of Commerce

APPCD Air Pollution Prevention and Control Division

BDL below detection limit

CAS# Chemical Abstract Service Registry Number

CD carpet detergent

CFR Code of Federal Regulations

CM carpet cleaning machine

CRI Carpet and Rug Institute

CT carpet treatment

DCC daily calibration check

FCBR front corner bedroom

HPLC high performance liquid chromatography

IAP internal audit program

IDL instrument detection limit

IS internal standard

LC/MS/MS liquid chromatography/tandem mass spectrometry

LOQ limit of quantification

MBR master bedroom

MDL method detection limit

MQO measurement quality objective(s)

MSDS material safety data sheet

NR not reported

NRMRL National Risk Management Research Laboratory

PFAA perfluoroalkyl acid

PFBA perfluorobutyric acid

PFC perfluorochemical

PFCA perfluorocarboxylic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

PFTeDA perfluorotetradecanoic acid

PFTrDA perfluorotridecanoic acid

PQL practical quantification limit

PTFE polytetrafluoroethylene

PTT polytrimethylene terephthalate

QAPP Quality Assurance Project Plan

QC quality control

RCS recovery check standard

RIS recovery internal standard

RSD relative standard deviation

TPFCA total perfluorocarboxylic acids (the sum of all monitored PFCAs)

U.S. EPA United States Environmental Protection Agency

15

## 1. Introduction

1.1 Background

The potential impacts of perfluorocarboxylic acids (PFCAs) on human health and the global

environment did not draw much attention until the turn of this century, when evidence of their

widespread presence in various environmental compartments appeared (Renner, 2001; Giesy and

Kannan, 2002). PFCAs have been detected in air, water, and soil (Boulanger et al., 2004; Stock et

al., 2007) and in a variety of wildlife around the world, including the United States (Kannan et al.,

2002), Arctic Canada (Martin et al., 2004), Europe, and the Mediterranean Sea (Giesy and Kannan,

2002). More recently, low levels of PFCAs have been found in various consumer products that are

either made from or treated with perfluorinated chemicals (Washburn et al., 2005; Guo et al.,

2009).

PFCAs persist in the environment due to their high stability, and there is evidence that they

bioaccumulate (Moody et al., 2002), a significant factor in their potential toxicity.

Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), two types of

perfluoroalkyl acids (PFAAs) that have been the most extensively studied PFCs to date, are

essentially ubiquitous in humans; they have been found in human blood and breast milk in the

United States (Tao et al., 2008; Calafat et al., 2006), China (So et al., 2006), and other countries

across Europe, South America, and Asia (Kannan et al., 2004). Toxicological studies indicate that

PFCAs cause developmental and systemic toxicity in laboratory animals (Kennedy et al., 2004;

Lau et al., 2004; U.S. EPA, 2005). In particular, PFOS has been shown to act as an endocrine

disruptor (Austin et al., 2003). The potential health risks associated with PFCAs have inspired

extensive research on the sources, transport, transformation, and distribution of these chemicals

and their precursors in environmental media, along with research into ways to reduce potential

health risks.

Despite significant progress thus far, researchers have yet to reach a consensus on the most

important routes by which the general population is exposed to these chemicals. In particular,

opinions differ on whether consumer products containing PFCAs are significant contributors to

overall exposure. For instance, a study in 2005 concluded that exposures to PFOA during

consumer use of the articles evaluated were not expected to cause adverse health effects in infants,

children, adolescents, or adults, or result in quantifiable levels of PFOA in human serum

(Washburn et al., 2005). In a study conducted in 2009 by Fromme et al., data from indoor

measurements in Canada and Norway were used to estimate the average daily intake of PFOA for

the general population in Western countries, and it was found that the inhalation of house dust

contributed only 0.6% of the average daily intake of PFOA and a maximum of only 8.2% of the

highest daily intake levels. By contrast, however, Tittlemier et al. (2007) identified treated

carpeting as an important source of PFOA exposure, second only to ingestion with food. Trudel et

al. (2008) agreed that the consumption of contaminated food is the most significant exposure

pathway for PFOA and that the ingestion of dust and inhalation of air containing PFOA is the

second most likely route of exposure in low- and intermediate-exposure scenarios. Their study also

found that direct, product-related exposure dominates in high-exposure scenarios in which

consumers have treated carpets in their homes or regularly use PFCA-containing products, such as

stain-protection sprays. It is apparent, then, that the scarcity of data related to indoor PFCA sources

16

### and exposures contributes to significant uncertainty and differences of opinion about the most

prevalent exposure routes for these compounds.

Elevated levels of PFCAs ha ve been detected in house dust in Japan (Moriwaki et al., 2003),

Canada (Kubwabo et al., 2005), and the United States (Strynar and Lindstrom, 2008), strongly

suggesting the presence of significant indoor sources. Kubwabo et al. correlated the percentage of

indoor carpet, in particular, to increased PFCA levels in dust. In 2005, Washburn and colleagues

reported the PFOA content in 14 groups of articles based on theoretical calculations and analytical

measurements. Of these groups, it was found that pre-treated carpet and carpet treated with carpetcare solution had the highest PFOA loadings, i.e., 0.2 to 0.6 mg and 0.2 to 2 mg of PFOA per kg,

respectively (Washburn et al., 2005). Previous research by Guo et al. (2009) examined 14 classes

of consumer products and also found pre-treated carpet and carpet treated with PFCA-containing

carpet-care solutions to have the largest PFCA source strength, i.e., approximately 70 mg of

PFCAs (C5 through C12) in a typical home. One study found that PFCA contamination was higher

on the inside than the outside of sampling films placed in windows (Gewurtz et al., 2009).

Gerwurtz’s study also found higher PFCA contamination in houses with new carpet and in carpet

stores, suggesting that emissions from new carpets contribute to increased indoor PFCA levels.

Due to the highly stable nature of PFCAs, few mechanisms exist, short of eliminating sources

completely, by which PFCAs can be removed from the indoor environment. Given its high source

strength and duration, its potential contribution to indoor dust, and its close proximity to humans,

treated carpeting may contribute to human exposure to PFCAs directly, e.g., dermal contact and

hand-to-mouth transfer, and indirectly via the inhalation of suspended particles from treated carpet.

1.2 Goal and Objective

The main go al of this study was to quantify the efficiency of common carpet cleaning methods

― steam cleaning and hot water extraction

― in the removal of PFCAs from residential and

commercial carpet that was manually treated with stain-protection solutions. Our aim in the study

was to determine if these cleaning techniques are viable methods for reducing indoor exposure to

PFCAs. These results will be valuable to policy makers and manufacturers for risk management

purposes and may be of particular interest to people who wish to reduce the levels of PFCA in their

household environments.

17

### ted in

use with

r

ximately 300 m

)

r bedroom (FCBR) and the master bedroom (MBR),

eted areas of the MBR and FCBR measured 13.4 m

loor p



### ouse was monitored but not reported for these experiments. An

n. Air exchange rate, temperature, and humidity were not

ut temperature and relative humidity

the 

## 2

tests were condu

style h ing system

and an electric m

a total volume of appr tes

(199 ouse

the front corn R),

For this study, the car 4 m

The air exchange rate inside the periments. An

OPTO 22 data acquisition syste temperature and

in the FCBR and d were not

ded and

conditions i ouse located in Cary, NC. Th

air hea

The total floor area is 12

Additional information on the

wo rooms of the

the front corner bedroom (FCBR) and the master bedroom (M

For this study, the carpeted areas of the MBR and FCBR measured 13

The air exchange rate inside the house was monitored but not reported for these e

continuously logge

in the FCBR and den. Air exchange rate, temperature, and humidit

were reco 

## 2. Materials and Methods

2.1 Test Facility

Carpet cleaning tests were conduc ted in a research h ouse located in Cary, NC. The research house

is a three-bedroom, ranch- style ho use with a crawl space, a central, forced- air heat ing system that

uses natural gas, and an electric a i r -conditioning system. The total floor area is 126 m 2 

### , and the

house has a total volume of appro ximately 300 m 3



### . Additional information on the tes t house was

provided by Tichenor et al. (1990 ) and Sparks et al. (1991). The t wo rooms of the h ouse employed

for this work were the front corne r bedroom (FCBR) and the master bedroom (MB R), as shown in

Figure 2.1. For this study, the carp eted areas of the MBR and FCBR measured 13. 4 m 2 

### and 12.2

m 2 

### , respectively.

Figure 2.1. Floor plan for the research house in Cary, NC



### The air exchange rate inside the h ouse was monitored but not reported for these ex periments. An

OPTO 22 data acquisition system (OPTO 22, Temecula, CA) continuously logged temperature and

humidity data in the FCBR and de n. Air exchange rate, temperature, and humidity were not

controlled as critical parameters, b ut temperature and relative humidity were recor ded and

reported. Additional conditions in the research house are listed in Table 2.1.

18Table 2.1. Conditions in the research house

Parameter 

### Status

Exterior doors and windows 

### Closed

Interior doors 

### Open

Ceiling fans 

### On low

Heating/air conditioning fan 

### On

Heating/air conditioning registers 

### Open

2.2 Test Materials

2.2.1 Carpet Selection for Research House Experiments

The following two carpet types were chosen for the research house experiments: 1) residential

carpet that was Green-Label Certified by the Carpet and Rug Institute (CRI) with a pile yarn

content of 100% polytrimethylene terephthalate (PTT) – a product from recycled plastic bottles –

with a textured cut pile and a woven polypropylene backing and 2) commercial carpet made with

Antron ® 

### fiber, a nylon 6,6, hollow-filament fiber with a soil-resistant treatment incorporated into

the fiber. The residential carpet fiber, also called Triexta ® 

### , shares the chemical structure of

polyester; however, unlike traditional polyester carpet, Triexta ® 

### has extreme durability, high stain

resistance, and a much softer texture. The fiber used for the commercial carpet is considered to be

one of the most durable in the industry, and it has been utilized extensively in schools and offices.

A solid urethane carpet pad was selected as the underpad for each type of carpet. Each of these

products was screened to determine the content of PFCAs prior to installation. A 1-g sample of

fiber from each type of carpet and 1 g of the solid memory foam backing carpet pad were analyzed

to determine their PFCA content before the experiments were initiated. All of the samples from all

of the products were found to contain less than 8 ng/g of PFCAs.

2.2.2 Professional Carpet Treatment Solutions

Two carpet stain-protection treatment solutions (CT-1 and CT-2) were selected using the following

criteria: (1) shown to contain high levels of PFCAs (greater than 10 times the PQL); and (2)

analytical data with good recovery for the recovery internal standards.

Table 2.2 lists the components of the selected treatment products as documented in each product’s

material safety data sheet (MSDS). The documentation indicated that both treatments are

dispersible in water. The PFCA content in these treatment solutions are reported in Section 3.2

below.

19Table 2.2. Components of carpet treatments CT-1 and CT-2

Chemical Content (%)

CT-1 CT-2

Polymethylmethacrylate (CAS# 9011-14-7) 1.3 – 2.5 4.7

NJ Trade Secret Registry #00850201001-5155P 1 – 1.5

–

NJ Trade Secret Registry #00850201001-5259P 0 – 1.3

–

Citric Acid (CAS# 77-92-9) 0.5 – 1

–

Water (CAS# 7732-18-5) 90 – 97 95



### 2.2.3 Carpet Cleaning Machines

Two carpet cleaning machines were chosen to clean the carpets after treatment with a carpet stainprotection treatment: 1) a residential cleaning machine (CM-1), the Rug Doctor Mighty Pro model

MP C-20 and 2) a portable professional steam cleaner (CM-2), the Century 400 Ninja Warrior.

Figure 2.2 shows the Rug Doctor (front) and the Ninja Warrior (rear). The residential machines,

which can be rented at most grocery and home improvement stores, use hot tap water for the

extraction process with no additional heating during the cleaning process. A 28-psi (1.93×10 5 

### Pa)

vacuum pump is used to extract the applied water, and a brush vibrates during the process. The

professional steam cleaner has an 1850-watt, in-line heater. Steam at a pressure of approximately

150 psi (1.03×10 6 

### Pa) soaks the carpet fibers, and dual 2-stage vacuum motors extract the residue

from the carpet. The professional cleaning machine does not agitate the carpet fibers.

Figure 2.2. Residential and commercial carpet cleaning machines



### 20

### 2.2.4 Carpet Cleaning Detergents

Two detergents were selected to test the removal of PFCAs from carpets, i.e., a residential carpet

cleaning detergent (CD-2) recommended for use with the residential machine (CM-1) and a

commercial carpet cleaning detergent (CD-1) chosen for use with the commercial machine (CM-2).

The residential detergent was purchased at a local grocery store, and the commercial detergent was

purchased from a local distributor of janitorial supplies. According to the material safety data

sheets (MSDSs), CD-1 contains 3 to 6% of dipropylene glycol methyl ether (CAS# 34590-94-8)

while CD-2 contains 1 to 5% of sodium 2-ethylhexyl sulfate (CAS# 126-92-1) and <1% of

branched tridecylalcohol (CAS# 69011-36-5). Prior to use, each cleaner was screened for PFCAs.

The residential detergent measured most PFCAs below the quantification limits of the instrument,

with perfluorotridecanoic acid (C 13 

### ) having the highest concentration at 3 ng/mL. The commercial

detergent had only trace levels of C 8 

### through C 10 

### , and all were below the practical quantification

limits.

2.3 Experimental Design

All experiments were conducted at the research house in Cary, NC. The FCBR was used primarily

for the residential carpet, and the MBR was used for both residential and commercial carpet. The

residential carpet was tested with both types of cleaning machines and detergents to represent what

might be used in a typical household, while the commercial carpet was tested with only the

commercial cleaning machine and the commercial detergent. An initial scouting test (Experiment

3) was performed with the residential carpet and CM-1 to finalize testing procedures before

beginning the planned experiments. To ensure the presence of detectable PFCAs, all experiments

involved the application of a commercial carpet stain-protection treatment solution containing

PFCAs (CT-1 or CT-2). Following the application of the treatment and a subsequent 48-hour

drying period, a series of three carpet cleanings was performed. A drying period of at least 48

hours followed each cleaning before carpet samples were collected. The first set of tests used only

hot water or steam for the cleaning process to determine the efficiency of each carpet cleaning

machine’s method of removing the applied PFCAs. Additionally, four experiments, one of which

was a duplicate test, were conducted using cleaning detergents (CD-1 or CD-2) in conjunction with

a carpet cleaning machine to assess any additional PFCA removal. The complete experimental test

matrix is summarized in Table 2.3.

21Table 2.3. Experimental matrix for testing of carpet care treatments

Experiment Research House

Location Carpet

Type c Treatment

Type Cleaning

Machine Detergent

1 MBR C CT-1 CM-2 None

2 MBR C CT-2 CM-2 None

3 a FCBR R CT-1 CM-1 None

4 FCBR R CT-1 CM-2 None

5 FCBR R CT-2 CM-2 None

6 MBR C CT-2 CM-2 CD-1

7 FCBR R CT-1 CM-1 CD-2

8 b MBR R CT-1 CM-1 CD-2

9 FCBR R CT-2 CM-2 CD-1

a Initial scouting test.

b Duplicate of Experiment 7.

c C = Commercial; R = Residential.



### 2.4 Test Procedure

2.4.1 Layout of Carpet Sampling Sections

The carpet in the MBR measured 3.66 × 3.66 meters, and the carpet in the FCBR measured 3.66 ×

3.20 meters. For each room, a grid was created in order to evenly gauge five sampling sections, AE, as shown in Figure 2.3. Once each section was located, a small piece of tape the size of a dime

was placed in its center. This was the only indicator placed on the carpet itself and acted as a

reference point for sampling (Section 2.5.1).

22A ▼ B ▼



### ▪ ▪

E ▼



### ▪

C ▼ D ▼



### ▪ ▪

Figure 2.3. Diagram of generic carpet sampling quadrant



### 2.4.2 Dilution and Application of the Carpet Treatment

The dilution of the carpet treatment varied slightly for each set of tests. The treatment (CT-1)

dilution for the scouting test (Experiment 3) was 1:1 distilled water to treatment solution to ensure

measurable concentrations of PFCA through three cleanings. The manufacturer’s recommendation

was 4:1, and the resulting concentrations of PFCAs from the 1:1 dilution on the carpet indicated

that a lower concentration of application treatment would be more applicable for this study;

therefore, a dilution of 4:1 was used for all subsequent applications with both products. An exact

measurement for the dilution was not critical because the dried product on the carpet fiber was

collected and extracted for analysis before each test.

To start the application, the diluted carpet stain-protection treatment solution was placed in a

commercial sprayer recommended in the product use guide for application of the treatment. The

sprayer was modified by adding a pressure gauge to better control the application rate and

uniformity of the application. Then, the sprayer was inserted into the “application cart,” an

apparatus manufactured in-house (Figure 2.4). The application cart was on wheels in order to

provide a more uniform application of the solution, and it held the nozzle of the sprayer

approximately 0.6 m from the ground.

23Figure 2.4. Application cart



### First, the carpet treatment was applied according to Figure 2.5. For each path, the applicator was

pumped to a pressure of 10 psi (6.89×10 4 

### Pa), the spray nozzle was turned on, and the cart was

pulled in the direction of the arrows for approximately 24 s. At the end of each path, the spray

nozzle was turned off. A grid on the wall allowed for proper path widths based on the swath of the

sprayer; the MBR had seven paths, while the FCBR had eight.

↓

↓

↓

↓

↓

↓

↓

End

(Door) 

### ↓

↓

↓

↓

↓

↓

↓

↓ ↓

↓

↓

↓

↓

↓

↓

↓ ↓

↓

↓

↓

↓

↓

↓

↓ ↓

↓

↓

↓

↓

↓

↓

↓ ↓

↓

↓

↓

↓

↓

↓

↓ Start

↓

↓

↓

↓

↓

↓

↓

↓

Figure 2.5. Diagram of first application process



### 24

### Once the application shown in Figure 2.5 was completed, a second, S-shaped application was

performe d, as shown in Figure 2.6. During this application, the process was not stopped at the end

of each path. Instead, the application was done in a continuous motion, only stopping to pump the

applicator to 8-10 psi (5.52×10 4 

### - 6.89×10 4 

### Pa) when necessary. After application the carpet was

allowed to dry for at least 48 hour before carpet samples were collected.

↓ ← ← ← ← ← ← ← ← ← ← Start

→ → → → → → → → → → → → ↓

↓ ← ← ← ← ← ← ← ← ← ← ←

→ → → → → → → → → → → → ↓

↓ ← ← ← ← ← ← ← ← ← ← ←

→ → → → → → → → → → → → ↓

End ← ← ← ← ← ← ← ← ← ← ←

Figure 2.6. Diagram of second application process



### 2.4.3 Cleaning of Carpets

The manufacturer’s instructions were followed for each carpet cleaning machine. When using the

commercial cleaner (CM-2), the carpets were cleaned in paths that were approximately 3-3.5 ft

(0.91-1.07 m) wide with about 1 in (2.54 cm) of overlap. Figure 2.7 demonstrates this process,

where each section of the schematic represents a path, and the arrows indicate the direction of

cleaning. For each path, there were four passes with the carpet cleaning apparatus with the cleaning

solution being expelled and vacuumed up in the first pass and any remaining solution being

vacuumed up in the final three passes, which, in turn, dried the carpet. Each 3-ft pass was timed for

approximately10 seconds. The residential cleaner (CM-1) followed a similar cleaning process,

except that 6-ft-wide paths were used.

25

### ↓

↓

↓ ↓

↓

↓ ↓

↓

↓ ↓

↓

↓ ↓

↓

↓ ↓

↓

↓ Start

↓

↓

↓

↓ ↓ ↓ ↓ ↓ ↓ ↓

↓ ↓ ↓ ↓ ↓ ↓ ↓

↓ ↓ ↓ ↓ ↓ ↓ ↓

↓ ↓ ↓ ↓ ↓ ↓ ↓

↓ ↓ ↓ ↓ ↓ ↓ ↓

↓ ↓ ↓ ↓ ↓ ↓ ↓

End

(Door) 

### ←←← ←←← ←←←

Figure 2.7. Diagram of carpet cleaning using commercial cleaner CM-2 (not to scale)



### 2.5 Sampling Methods

2.5.1 Collection of Carpet Samples

A carpet sample from each of the five sampling locations (Figure 2.3) was collected according to

Table 2.4, using a 82-mm-diameter carpet cutter (05-174 Instant Repair Tool, Crain Cutter

Company, Milpitas, CA). Methanol was used to clean the tool between samples to prevent crosscontamination. Each sample was placed in an individually-labeled plastic bag and transferred to the

EPA campus for processing and analysis. Each 82-mm-diameter carpet sample was processed by

removing the fibers from the backing and placing them in an aluminum foil dish. Each set of carpet

samples was placed in a separate dessicator. After a minimum of 16 hours, the fiber sample was

removed and mixed. A 1-g sub-sample was transferred to a 50-mL polypropylene centrifuge tube

(Evergreen Scientific, Los Angeles, CA), and a second 1-g sub-sample was weighed and placed in

a plastic bag. Once all individual samples from the stage had been processed, the plastic bag

containing the remaining 5 g of carpet from quadrants A-E were used to compile five composite

fiber samples. The bag was shaken to ensure that all fibers were distributed evenly, and five

individual 1-g sub-samples of composite carpet fiber were removed from the plastic bag and

placed in separate centrifuge tubes. In summary, each stage of the experiment produced a total of

10 samples, each weighing 1 g, i.e., five individual fiber samples (A-E) and five composite fiber

samples composed of fibers from all five sampling locations. The individual sample data were used

only to evaluate the uniformity of the application of the carpet treatment, while the composite

samples were used to evaluate cleaning efficiency.

26Table 2.4. Carpet fiber collection strategy

Stage of Experiment Number of Samples

Collected from Carpet Number of Fiber

Samples Processed for

Analysis a Number of Composite

Fiber Samples

Processed for Analysis b

Prior to Treatment

Application (Initial

Sampling) 5 5 5

Post-Treatment

Application

(Application Sampling) 5 5 5

Post-cleaning, Round 1

(Clean 1 Sampling) 5 5 5

Post-cleaning, Round 2

(Clean 2 Sampling) 5 5 5

Post-cleaning, Round 3

(Clean 3 Sampling) 5 5 5

a One ~1-g sample per sampling location.

b Five ~1-g samples taken from an equal mixture of fiber samples from all five locations.



### Figure 2.8 shows a residential carpet after all sampling stages were completed.

Figure 2.8. Residential carpet after all sampling stages



### 2.5.2 Wipe Sampling

Wipe samples were collected only during Experiment 3, the scouting test, to evaluate over-spray

during the application process. These data illustrate any possible exposure from wall surfaces in a

typical home. Using ASTM Method D 6661, Field Collection of Organic Compounds from

Surfaces Using Wipe Sampling (ASTM, 2010)

, as a general guideline, a 10 cm × 10 cm template

27

### was used to outline the wipe area using painters tape. Four wipe areas were sampled on each of the

four walls in the center of the carpet length, four inches above the baseboard molding. For each

wipe sample, approximately 2 mL of methanol were applied to a piece of cotton gauze. The gauze

was pressed firmly to the wall, and the sample area was wiped vertically with minimal overlap

between strokes. Then, the sample area was wiped horizontally. The gauze used for the wipe was

stored in a 50-mL polypropylene centrifuge tube and later extracted using the same procedure that

was used for the residential carpet samples, which is described in Section 2.6.1. Background wipe

samples were collected at each location before application of the carpet treatment.

2.6 Sample Analysis

2.6.1 Extraction of Residential Carpet Samples

To each of the residential fiber samples prepared in Section 2.5, 45 mL of HPLC-grade methanol

(pre-screened for PFCAs) and 100 μL of recovery check standard (2 ng/μL each of perfluoro- n -[1,

2- 13 

### C 2 

### ] decanoic acid Wellington Laboratoies, Canada) were added. The samples were extracted

for 24 ± 2 hr using a Nutating Mixer (Model VSN-5, PRO Scientific, Inc., Oxford, CT). The

extract was transferred to a 170-mL borosilicate glass blow-down tube. The original sample vial

was rinsed three times with ~3 mL of methanol, and each of the rinse liquids was transferred to a

170-mL concentration tube. A spatula was used to agitate the samples during rinsing. Next, the

sample was concentrated to approximately 1.5 mL in a heated (50 °C) nitrogen atmosphere by

using a RapidVap N 2 

### Evaporation System (Model 791000, LabConco, Kansas City, MO), which

was previously modified at the factory to remove all PTFE parts and coatings.

The blow-down sample was transferred to a 10-mL volumetric flask through a 0.1- μ m Anotop

syringe filter (Whatman International, Madestone, England). The tube was rinsed five times with a

solution consisting of 60% (v/v) methanol and 40% (v/v) 2 mM ammonium acetate aqueous

solution (hereafter referred to as 60:40 solution). The rinse liquids were filtered and combined with

the blow-down sample in the volumetric flask. After adding 100 μL of the internal standard

solution (0.5 ng/μL each of perfluoro- n -[1, 2, 3, 4- 13 

### C 4 

### ] octanoic acid), the sample was brought

to10 mL with 60:40 solution and sonicated for 10 min. The sample solution was transferred to a

15-mL polypropylene tube and stored at 4 °C until LC/MS/MS analysis.

2.6.2 Extraction of Commercial Carpet Samples

After extraction, due to clogging of the 0.1- μ m Anotop filter, the sample first had to be first filtered

through a Corning 0.22- μ m cellulose acetate, low-binding filter and into a polystyrene tube. The

170-mL concentration tube was rinsed five times, and the extract was passed through the 0.22- μ m

Corning filter. Then, the sample extract was transferred through a 0.1- μ m Anotop syringe filter into

a 10-mL volumetric flask. The filter tube was rinsed five times with 60:40 solution into the flask.

After adding 100 μL of the internal standard solution, the sample was brought to volume with

60:40 solution and sonicated for 10 min. The sample solution was transferred to a 15-mL

polypropylene tube and stored at 4 °C until LC/MS/MS analysis.

28

### 2.6.3 Extraction of Liquid Samples

Approximately 1 mL of the liquid sample was weighed, spiked with 1 mL of a 2 ng/μL recovery

check standard solution, and diluted to 10 mL with 60:40 solution. The diluted samples were

sonicated for 10 min and then filtered with a 0.1- μ m Anotop syringe filter. After filtration, 1 mL of

the filtrate was transferred into a 10-mL volumetric flask and spiked with 100 μL of the internal

standard. The resulting solution was sonicated for 10 min, transferred to a polypropylene tube, and

stored at 4 °C until LC/MS/MS analysis. Note: for samples with levels of PFCAs above the

calibration range, a second dilution of 1:10 was needed before adding the recovery check standard.

2.6.4 QC Sample Preparation

A set of five quality control (QC) samples was prepared for every batch of carpet extractions, i.e., a

field blank, a solvent blank, and three recovery internal standard blanks. The field blank consisted

of 45 mL of methanol and 100 μ L of recovery internal standard, and it went through the same

extraction process as the residential carpet samples described in Section 4.6.1. The solvent blank

consisted of 60:40 solution with 100 μ L of internal standard, brought to volume in a 10-mL

volumetric flask. Each recovery internal standard blank contained 60:40 solution with 100 μ L

internal standard and 100 μ L recovery internal standard, brought to volume in a 10-mL volumetric

flask. All samples including field blank samples were sonicated, transferred to 15-mL

polypropylene tubes, and stored at 4 °C with the corresponding batch of extraction samples until

LC/MS/MS analysis. The analyte content in the solvent blank was subtracted from all samples and

field blanks if it exceeded the practical quantification limit (PQL). The analyte content in the field

blanks was required to be below the PQL.

2.6.5 Sample Analysis

Sample quantification was conducted using an Agilent 1100 HPLC equipped with an Applied

Biosystems API 3200 Triple Quadrupole Mass Spectrometer with a Turbo V ion-spray interface. A

C18 reversed-phase guard column and analytical C18 reversed phase column were used for analyte

separation. Samples were injected at a flow rate of 0.250 mL/min and maintained at 50 °C. The

initial gradient mobile-phase composition was 25% mobile phase B, where mobile phase A was

95% 2 mM aqueous ammonium acetate-5% methanol, and mobile phase B was 95% methanol-5%

2 mM aqueous ammonium acetate, held for 0.5 min. A linear gradient was used from 25% to 85%

B over 4.5 min, then increased to 100% B over 0.10 min and held for 2 min. Then, a linear gradient

decreased mobile phase B to 25% over 2 min, where it was held for 3 min. PFCAs were observed

in the negative ion mode, and both primary and secondary ion transitions were collected for each

analyte. The instrument was calibrated for 11 PFCA homologues (Table 2.5) plus the recovery

check standards at eight concentration levels in the concentration range of 0.3 to 100 ng/mL with

triplicate injections. This procedure followed methods detailed in Liu et al. (2009).

29Table 2.5. Analyte names, abbreviations, chemical formulas, molecular weights (g/mol), and

Chemical Abstracts Service registration numbers (CAS #)

Analyte Abbreviation Formula MW CAS #

Perfluorobutyric acid PFBA – C4 C 4 HF 7 O 2 214.04 375-22-4

Perfluoropentanoic acid PFPeA – C5 C 5 HF 9 O 2 264.04 2706-90-3

Perfluorohexanoic acid PFHxA – C6 C 6 HF 11 O 2 314.05 307-24-4

Perfluoroheptanoic acid PFHpA – C7 C 7 HF 13 O 2 364.05 375-85-9

Perfluorooctanoic acid PFOA – C8 C 8 HF 15 O 2 414.06 335-67-1

Perfluorononanoic acid PFNA – C9 C 9 HF 17 O 2 464.07 375-95-1

Perfluorodecanoic acid PFDA – C10 C 10 HF 19 O 2 514.07 335-76-2

Perfluoroundecanoic acid PFUdA – C11 C 11 HF 21 O 2 564.08 2058-94-8

Perfluorododecanoic acid PFDoA – C12 C 12 HF 23 O 2 614.09 307-55-1

Perfluorotridecanoic acid PFTrDA – C13 C 13 HF 25 O 2 664.11 72629-94-8

Perfluorotetradecanoic acid PFTeDA – C14 C 14 HF 27 O 2 714.12 376-06-7

Perfluoro- n -[1,2- 13 C 2 ]

hexanoic acid a 13C-PFHxA 13 C 2 12 C 4 HF 11 O 2 316.04 n/a

Perfluoro- n -[1,2,3,4- 13 C 4 ]

octanoic acid b 13C-PFOA 13 C 4 12 C 4 HF 15 O 2 418.03 n/a

Perfluoro- n -[1,2- 13 C 2 ]

decanoic acid a 13C-PFDA 13 C 2 12 C 8 HF 15 O 2 516.07 n/a

a Recovery check standard.

b Internal standard.



### 2.7 Quality Assurance and Quality Control

A Category II quality assurance project plan (QAPP) was developed and approved before the start

of the project and detailed the Measurement Quality Objectives (MQOs) for the project, which are

summarized in Table 2.6. For this study conducted at the EPA research house, the data quality

objective for the precision of solvent extraction was relaxed to ± 30% to incorporate more

information to better interpret the desired goal of this project. All data that fell outside the original

MQOs listed below are highlighted in the data tables presented in Appendix A.

30Table 2.6. Measurement quality objectives

Measurement Parameter Objective Method

Calibration of

LC/MS/MS Coefficient of

determination (r 2 ) for

calibration curve > 0.99 Linear regression

Instrument

detection limit ≤ 0.2 ng/mL EPA method (40 CFR 136, 1986)

PFCA quantification

by LC/MS/MS Accuracy 85-115% Internal audit program

Daily calibration check standards

Precision 20% RSD for duplicate injections

Agreement of primary

and secondary ions 25% Percent deviation

(in highest 10% of samples)

Precision 20% a RSD for replicate extractions

Solvent extraction Accuracy 80-120% Recovery internal standard

System blank < IDL Extraction w/o AOC b sample

Weight of AOC samples Accuracy ±2 mg NIST-traceable weights

a For data completeness, some extraction results presented below had precisions between 20% and 30%;

data with precisions of greater than 30% were discarded.

b Articles of Commerce.



### 2.7.1 Uniformity of Carpet Protector Treatment Solution

The variability of the carpet treatment application and the inconsistency of the cleaning machine

process (temperature, time of cleaning in single location, and operator variations) made the

collection of truly duplicate carpet samples impossible. Individual samples from each of the five

sampling locations were collected at each stage of the experiment, as indicated previously in

Figure 2.3. Sampling in five different locations accounted for potential variations in both the

treatment application and carpet cleaning. These five samples were analyzed individually and also

combined to create a large mass composite carpet fiber sample. The accumulation and mixing of

sub-samples from different locations eliminated application and cleaning variability and lack of

uniformity in treatment applications. Five 1-g samples were removed from the composite samples

after mixing. These replicate samples served as proxy duplicates. Figure 2.9 presents the results of

the average of the five individual samples collected from positions A-E post-application from each

experiment to demonstrate variations in the application of the treatment. A high standard deviation

for the averages of the individual samples is an indicator of application variability. These data from

individual samples are presented in Appendix A. The composite samples, as a physical average of

carpet conditions, ideally would reduce these inconsistencies in PFCA deposition and removal.

3116000

12000

8000

4000

0



### ExperimentAverage TPFCAs (ng/g)

1 2 3 4 5 6 7 8 9

Figure 2.9. Average of individual quadrant samples for post-application PFCA concentrations in each

experiment and associated standard deviations



### 2.7.2 Calibration of LC/MS/MS

The instrument was calibrated for 11 PFCA homologs (Table 2.5) plus the recovery check

standards at eight concentration levels in the concentration range of 0.3 to 100 ng/mL with

triplicate injections. The instrument detection limits (IDLs) for individual PFCAs in the injected

sample were ≤ 0.2 ng/mL. The practical quantification limit (PQL) for the injection sample was < 1

ng/mL, which is equivalent to 1 ng/g for carpet extracts and 10 ng/g for liquid samples.

Initially, standards were prepared from individual analytes (Liu et al., 2009). However, in March

2010 calibrations were performed using a composite standard mix distributed by the manufacturer

that contained the all of the analytes of interest. This change was due to the availability of a

composite standard and the resulting simplification of the standard preparation process.

The acceptance criterion for the calibration curve was that the coefficient of determination (r 2 

### ) be

no less than 0.99. The average of the r 2 

### values for 14 compounds over seven calibrations was 0.995

± 0.003, giving 100% completeness for the MQO for calibration.

An internal audit program (IAP) standard was analyzed for each of the seven calibrations. The IAP

standard contained at least three of the calibrated PFCAs using a different chemical source

(Oakwood Laboratories or Aldrich) and was prepared by someone other than the analyst who

prepared the calibration standards. The analyst who conducted the calibration received the IAP

standard without knowing the concentrations. IAP standards were analyzed after each calibration

as a measurement of calibration verification. The average of the percent accuracy for each analyte

32

### ranged from 76% to 115%. Only two data points out of 26 did not meet the MQO criterion for

acceptance of ± 15%, giving 92% completeness for this QA criterion.

2.7.3 Daily Calibration Checks

Daily calibration check (DCC) standards, approximately 10 ng/mL for each analyte, were analyzed

to evaluate the performance of the LC/MS/MS. The DCC was conducted at the beginning of each

analytical sequence and at the end of the sequence or, for extended sequences, after 24 hours of

instrumental analysis. Analytical results of a sample batch were considered acceptable only if the

percent recovery of the DCC was within 100 ± 15% and the percent relative standard deviation

(%RSD) of triplicate injections of the DCC was within ± 15%. The MQO for DCC recovery was

relaxed for this study to 100 ± 30%, and the percent relative standard deviation (%RSD) of

triplicate injections of the DCC was instead required to be within ± 30%. Data that fell outside the

original MQO for DCCs are highlighted in the data tables in Appendix A. Data that fell outside the

relaxed MQOs were not used in this report. We collected 952 data points for the DCC

measurements with only 55 points falling outside the relaxed MQO, giving 94% completeness

using the relaxed MQO.

2.7.4 Contamination Checks

All purchased and prepared solvents, glassware, and the HPLC system were checked routinely for

PFCA contamination. Also, a solvent blank was prepared with each set of standards and samples to

assess the solvent and the HPLC system. Solvents and blanks were rejected if they contained the

analytes of interest at concentrations higher than the IDL for individual PFCAs in the injection

sample of ≤ 0.2 ng/mL.

2.7.5 Weight Measurements

Two balances were employed for weight measurements during this project, i.e., 1) a five-place

microbalance and 2) a three-place pan balance. The microbalance was used early in the project for

weighing the calibration standards for the LC/MS/MS. Both balances are calibrated every 12

months. To monitor the daily performance of the balances, two Class A weights were weighed at

the beginning and end of each weigh session. The precision of each balance for this project was

determined by averaging the measurements for each class A weight and determining the standard

deviation for those measurements. The accuracy was determined by comparison of the class A

weight measurement to the certified value of the weight. Table 2.7 presents these MQO

measurements.

Table 2.7. MQOs for weight measurements

Parameter Microbalance Pan Balance

Precision (n > 10) 10 mg: 9.997 ± 0.038 mg

20 g: 19.999 ± 0.00014 g 1 g: 1.000 ± 0.001 g

10 g: 10.002 ± 0.001 g

Accuracy % 10 mg: 99.97%

20 g: 99.99% 1 g: 100.05%

10 g: 100.01%



### 33

## 3. Results

3.1 Summary of Experimental Conditions

The research house conditions for the nine experiments are summarized in Table 3.1.The relative

humidity and air exchange rate were measured but not controlled during the research house

experiments. After each application and subsequent cleaning, the relative humidity was elevated

for several hours during the drying period for the carpets. The temperature was controlled by the

conventional heating and air conditioning system in the house. The HVAC fan was operated

continuously, and the ceiling fans in the FCBR, MBR, den, and living room were kept on low

speed, blowing upward. Measurements for relative humidity and temperature were monitored in

the FCBR and den by a Vaisala INTERCAP humidity and temperature transmitter recording to an

OPTO DAS. The air exchange rate inside the house was not reported for any of the experiments.

The only purpose of presenting the environmental data in Table 3.1 is to show that the carpet

cleaning experiments were conducted under typical indoor environmental conditions. The data was

not used anywhere else in this report.

Table 3.1. Environmental parameters recorded during the cleaning experiments

Experiment a Temperature, 0 C b Relative Humidity, % b

Average c High Low Average c High Low

1 and 4 22 ± 1 d

24 ± 0.5 e 24

25 20

22 59 ± 6

54 ± 4 77

65 48

44

2 and 5 22 ± 1 d

24 ± 1 e 24

26 20

22 61 ± 4

56 ± 2 75

65 55

51

3 21 ± 1 d

19 ± 1 e 26

22 19

18 24 ± 6

25 ± 4 58

40 14

18

6 and 9 21 ± 1 d

23 ± 0.5 e 23

25 19

21 59 ± 6

52 ± 4 75

63 47

42

7 and 8 NA f NA f NA f NA f NA f NA f

a Tests are grouped together by the start date for each test (one test being conducted in the FCBR and

the other in the MBR). Test 3 was the initial scouting test conducted in the FCBR.

b Measurement locations: front corner bedroom (FCBR) and den.

c Mean ± standard deviation for n > 2500 (Sample number varied with each experiment).

d Transmitter in the FCBR.

e Transmitter in the Den.

f Not available

― Data lost due to power failure at the house.



### 3.2 Extractable PFCA Content in Carpet Treatment Solutions

The levels of PFCAs quantified in the undiluted carpet protector treatments CT-1 and CT-2 are

presented in Figure 3.1. The error bars show ±1 standard deviation with n = 4 for CT-1 and n = 6

34

### for CT-2. The treatments were analyzed for 11 PFCAs; however, the levels of PFTeDA (C14) in

the treatment solutions were below the limit of detection. The total PFCA content for CT-1 and

CT-2 was, respectively, 6360 and 7500 ng/g.

0 500 1000 1500 2000 2500Concentration (ng/g) 

### CT-1

CT-2

Figure 3.1. Extractable PFCA content in carpet treatment solutions CT-1 and CT-2

(The error bars represent ±1 SD; n = 4 for CT-1 and n = 6 for CT-2)



### 3.3 Extractable PFCA Content in Wipe Samples Taken from the Walls

The results from the wipe samples collected during Experiment 3 to evaluate overspray during the

application process are presented in Table 3.2. Background wipe samples were collected from each

of the four locations prior to the application of the carpet stain-protection treatment. Three of the

four background samples showed no evidence of PFCAs on the walls prior to application. The

fourth background sample was lost during analysis. The concentration of PFCAs measured on the

wall varied significantly from location to location, ranging from 2.3 ng/cm 2 

### to 47.4 ng/cm 2 

### . This

exposure source is minimal when compared to the post-application concentration on the carpet of

approximately 4000 ng/cm 2 

### of carpet area, as measured from the protectant application rate on the

carpet.

35Table 3.2. Results of wall wipe samples collected during Experiment 3

Wipe Samples Wipe A,

ng/cm 2 Wipe B,

ng/cm 2 Wipe C,

ng/cm 2 Wipe D,

ng/cm 2

PFBA-C4 0.8 1.0 0.1 b 1.4

PFPeA-C5 0.5 0.7 0.0 b 1.0

PFHxA-C6 2.5 3.3 0.2 5.3

PFHpA-C7 6.9 8.6 0.4 10.9 b

PFOA-C8 3.8 4.7 0.2 6.1

PFNA-C9 4.5 5.9 0.3 7.8

PFDA-C10 2.9 3.9 0.2 4.9

PFUnDA-C11 2.4 3.2 0.1 4.1

PFDoDA-C12 1.8 2.2 0.2 b 2.7

PFTrDA-C13 1.2 1.4 0.1 b 1.5

PFTeDA-C14 1.8 b 1.9 b 0.5 b 2.0

Total PFCA, ng/cm 2 29.1 36.8 2.3 47.7

Perfluoro- n -[1,2-13C2] decanoic acid

(recovery check standard) 113% 117% 120% 121% a

a Did not pass MQO of ± 20% but is presented with the relaxed MQO.

b nn = values below quantification limit; nn = values above calibration range.



### 3.4 Extractable PFCA Content in Carpet Samples

The concentrations of individual PFCAs and total PFCA in composite carpet fiber samples for

Experiments 1 through 9 are presented in Appendix A, Tables A.1 through A.9. The results of total

PFCAs are presented graphically in this section in Figures 3.2 through 3.10. The composite

samples represent fibers collected from each of the five sampling locations compiled into one

sample and then divided into five replicate samples. The data in each graph represent the reportable

data using both the QAPP standard MQOs and the relaxed MQOs from each experiment. The

relaxed data are highlighted in the data tables in Appendix A. The error bars represent the

variability between replicate samples and are equal to ± one standard deviation.

In the following graphs, each experiment is coded with the parameters of the experiment as

presented in Table 4.3. The resulting code is presented as: Type of carpet: R = residential or C =

commercial; carpet stain-protection treatment: 1 or 2; carpet cleaning machine: 1 or 2; and carpet

detergent: 0 = no detergent, 1 or 2 [i.e., Experiment 1 (C-1-2-0) = Commercial carpet, CT1, CM1,

and no detergent].

It was noticed that the commercial carpet (see Figures 3.2, 3.3, and 3.7) retained more PFCAs after

treatment than the residential carpet did.

360 1000 2000 3000 4000 5000 6000Concentration (ng PFCAs / g carpet)

Pre-Application Post-Application Post-Cleaning Post-Cleaning Post-Cleaning

Round 1 Round 2 Round 3

Figure 3.2. Average total PFCAs in composite carpet fiber samples for Experiment 1 (C-1-2-0)

0 2000 4000 6000 8000 10000Concentration (ng PFCAs / g carpet)

Pre-Application Post-Application Post-Cleaning Post-Cleaning Post-Cleaning

Round 1 Round 2 Round 3

Figure 3.3. Average total PFCAs in composite carpet fiber samples for Experiment 2 (C-2-1-0)



### 370 1000 2000 3000 4000Concentration (ng PFCAs / g carpet)

Pre-Application Post- Post-Cleaning Post-Cleaning Post-Cleaning

Application Round 1 Round 2 Round 3

Figure 3.4. Average total PFCAs in composite carpet fiber samples for Experiment 3 (R-1-1-0)

Pre-Application Post-Application Post-Cleaning Post-Cleaning Post-Cleaning

Round 1 Round 2 Round 3

Figure 3.5. Average total PFCAs in composite carpet fiber samples for Experiment 4 (R-1-2-0) 0 500 1000 1500 2000 2500 3000Concentration (ng PFCAs / g carpet)



### 380 1000 2000 3000 4000Concentration (ng PFCAs / g carpet)

Pre-Application Post-Application Post-Cleaning Post-Cleaning Post-Cleaning

Round 1 Round 2 Round 3

Figure 3.6. Average total PFCAs in composite carpet fiber samples for Experiment 5 (R-2-2-0)

0 3000 6000 9000 12000Concentration (ng PFCAs /g carpet)

Pre-Application Post-Application Post-Cleaning Post-Cleaning Post-Cleaning

Round 1 Round 2 Round 3

Figure 3.7. Average total PFCAs in composite carpet fiber samples for Experiment 6 (C-2-2-1)

[Re-use of carpet from Experiment 2]



### 390 1000 2000 3000 4000Concentration (ng PFCAs / g carpet)

Pre-Application Post-Application Post-Cleaning Post-Cleaning Post-Cleaning

Round 1 Round 2 Round 3

Figure 3.8. Average total PFCAs in composite carpet fiber samples for Experiment 7 (R-1-1-2)

0 1000 2000 3000 4000 5000Concentration (ng PFCAs / g carpet)

Pre-Application Post-Application Post-Cleaning Post-Cleaning Post-Cleaning

Round 1 Round 2 Round 3

Figure 3.9. Average total PFCAs in composite carpet fiber samples for Experiment 8 (R-1-1-2),

duplicate of Experiment 7



### 400 1000 2000 3000 4000 5000Concentration (ng PFCAs / g carpet)

Pre-Application Post-Application Post-Cleaning Post-Cleaning Post-Cleaning

Round 1 Round 2 Round 3

Figure 3.10. Average total PFCAs in composite carpet fiber samples for Experiment 9 (R-2-2-1)

[Re-use of carpet from Experiment 5]



### 3.5 Percent Removal of PFCAs by Cleaning

For each experiment, the percent removal of total PFCAs after the final cleaning was calculated by

comparison of the total PFCA concentration after application of the carpet treatment to the total

PFCA concentration after the third round of cleaning. These data are presented in Appendix A,

Tables A1 through A9. Figure 3.11 is a graphic representation of these results.

410% 20% 40% 60% 80% 100%Total Percent Removal

1 2 3 4 5 6 7 8 9



### Experiment

Figure 3.11. Calculated percent removal of total PFCAs for each experiment



### 42

## 4. Discussion

4.1 Removal Efficiency of Speciated Extractable PFCAs in Carpet Samples

A relative comparison of the post-application concentration of the speciated carpet treatment to the

concentration after the third cleaning for each experiment as percent removal of individual

compounds PFPeA-C5 through PFDoDA-C12 is presented in Table 4.1. PFBA-C4 and PFTrDAC13 are not presented due to incomplete data sets. Three of the four experiments with detergent (7,

8, and 9) and two of the experiments without detergent (4 and 5) present a clear trend that the

higher removal efficiency was associated with the lower molecular weight compounds rather than

high molecular weight compounds. This trend is confirmed in the comparison of duplicate

experiments 7 and 8. However, in experiments 1, 2, 3, and 6, the trend indicated that the removal

efficiencies were more uniform. No clear conclusion about speciated removal efficiency could be

determined from these data.

Table 4.1. Percent removal efficiency of speciated compounds

Experiment 1 (C120) 2 (C220) 3 (R110) 4 (R120) 5 (R220) 6 (C221) 7 (R112) 8 (R112) 9 (R221)

PFPeA-C5 29% 63% 57% 100% NR 60% 89% 79% 84%

PFHxA-C6 29% 70% 70% 100% 89% 70% 94% 91% 91%

PFHpA-C7 28% 62% 58% 52% 76% 64% 80% 73% 81%

PFOA-C8 44% 67% 40% 27% 38% 73% 47% 43% 61%

PFNA-C9 25% 70% 38% 18% 39% 81% 13% 30% 64%

PFDA-C10 28% 64% 59% 22% 84% 81% 73% 64% 58%

PFUnDA-C11 3% 59% 44% 5% 4% NR 4% 23% 79%

PFDoDA-C12 19% 59% 49% 14% NR 89% 43% 20% 70%



### 4.2 Overall PFCA Removal Efficiency

For the nine cleaning tests conducted, the overall PFCA removal efficiency after three rounds of

cleaning ranged from 26% to 76% (Table 4.2). Repeated cleanings with and without detergent did

not return either carpet to its pre-application concentration of < 8 ng/g of TPFCAs. On average,

each round of carpet cleaning removed approximately 20% of the total PFCAs. The overall

removal efficiency of the PFCAs could be attributed to the differences in the carpet fibers of each

of the products. Although there was high variability in the percent of PFCAs removed in each

round of cleaning (Appendix A), certain trends were evident. In general, the first round of carpet

cleaning resulted in the largest decrease in PFCAs. The decrease in PFCAs from the second to the

third cleaning continued to show removal of PFCAs, albeit with less efficiency, almost indicating a

leveling off of PFCA removal with each cleaning system.

43Table 4.2. Composite carpet sample data summarizing average percent reduction in

PFCAs by experiment

Experiment Experimental ID Total Removal, %

1 C-1-2-0 26%

2 C-2-2-0 64%

3 R-1-1-0, scouting 52%

4 R-1-2-0 45%

5 R-2-2-0 63%

6 C-2-2-1 76%

7 a R-1-1-2 58%

8 a R-1-1-2 46%

9 R-2-2-1 70%

a Duplicate experiments.



### 4.3 Comparison of Duplicate Experiments

Experiments 7 and 8 were performed using the same residential carpet, treatment, cleaning

machine and detergent and represents the only duplicate experiment that was conducted.

Experiment 8 had slightly higher initial PFCA concentrations than Experiment 7. Analysis for

average PFCA removal following each round of cleaning showed less than 30% variance between

the duplicate experiments, which was within the ± 30% deviation indicated in the relaxed MQOs

for this investigation, suggesting that these data are reproducible.

4.4 Factors Affecting the Efficiency of PFCA Removal

To investigate the data more closely, average reductions in PFCAs were examined by experimental

variable. These data are presented in Table 4.3 and Figure 4.1. Although it is not possible to draw

statistically relevant conclusions due to the large number of variables relative to the number of

experiments and the cross-correlation of the variables, some preliminary conclusions can be drawn.

A detergent, either CD-1 or CD-2, was used in Experiments 6 through 9. The detergent was used in

addition to the carpet cleaning machine potentially to enhance PFCA removal. As compared to

Experiments 1 through 4, the experiments that used detergent exhibited no statistically significant

increases in percent removals of PFCAs after three rounds of cleaning. As compared by detergent

(none vs. 1 or 2), CD-1 does appear to have removed a greater amount of PFCAs, 73% as

compared to ≥ 50% for both CD-2 and no detergent, but percent removals for most individual

experiments ranged from 45% to 76% regardless of detergent use. A larger number of replicate

experiments would be needed to determine with greater certainty the effects of detergent

application.

44Table 4.3. Average percent reduction in PFCAs by experimental variable

for composite samples

Variable Type Tota l Removal

Carpet Residential 56%

Commercial 55%

Treatment CT-1 46%

CT-2 68%

Carpet Cleaning CM-1 52%

Machine CM-2 57%

CD-1 73%

Detergent CD-2 52%

No Detergent 50%Average PFCA Removal 100%

80%

60%

40%

20%

0%ResidentialCommercialCT-1CT-2CM-1CM-2CD-1CD-2None

Carpet Protectant Carpet Cleaning Detergent

Machine

Figure 4.1. Average percent reduction in PFCAs by experimental variable

for composite samples



### 45

### The concentrations presented in these results represent PFCAs available via methanol extraction,

which may not equal the level of PFCAs available under actual normal use conditions for carpet.

For example, it has been shown that extraction of PFCAs from carpets using either water or sweat

(laboratory-prepared sweat simulant), which are more common household solvents than methanol,

recovered only about 10% to 65% of the PFCAs that were recovered with up to 24 hours of

methanol extraction (Mawn et al., 2005). As treated carpet ages, wear and fiber degradation may

also increase the availability of PFCAs through methods such as dust formation or transfer to other

surfaces.

4.5 Composite vs. Individual Samples

The analysis of individual quadrant samples was conducted only to show the uniformity of the

application of the carpet treatment, as presented in Section 2.7.1, Figure 2.9. Complete uniformity

of application is not possible with the manual application procedure that was recommended by the

manufacturer of the carpet treatment products. Thus, the discussion focused only on the data

obtained from composite carpet samples.

4.6 Extractable PFCA Content Collected from Walls

The collection of wipe samples from the wall surfaces was conducted during the initial scouting

experiment as a point of interest and does not concern the central discussion of PFCA removal

from carpets. However, these samples do demonstrate that PFCAs are, in fact, deposited on the

surface of the walls during the process of applying a carpet treatment (Table 3.2). Although the

reported concentration of PFCAs on the surfaces of the walls was several orders of magnitude

lower than that applied to the carpet, the presence of PFCAs on the walls after applying a carpet

treatment should still be noted.

46

## 5. Conclusions and Recommendations

The efficiency of PFCA removal from treated carpet by hot water extraction and stream cleaning

was evaluated under close-to-realistic conditions in a research house. On average, each carpet

cleaning event removed approximately 20% of total PFCAs. At this removal efficiency, it takes

three, seven, and ten rounds of cleaning to remove, respectively, 50%, 80%, and 90% of total

PFCAs.

The average American home has about 1000 square feet (93 m 2 

### ) of carpet. Previous research has

shown that treated carpets represent one of the largest sources of PFCAs in homes. Additionally,

PFCAs are highly stable, with the potential for a long residence time indoors, and can also bind to

house dust, making it difficult to remove the PFCAs from the indoor environment by any available

mechanisms. The use of a carpet cleaning machine may be a risk management option for people

who wish to reduce their indoor exposure to PFCAs. However, as mentioned above, this method is

only modestly effective in removing PFCAs from treated carpet.

Using the household hot water machine in four experiments with the residential carpet, reductions

of PFCA averaged between 45% and 58% after three rounds of cleaning. The removal efficiency

using the commercial cleaning machine on the commercial carpet had the highest variability. The

results from two experiments using the commercial cleaning machine with a steam extraction

indicated only a 26% reduction of PFCAs for carpet treatment 1 (CT-1), but there was a reduction

of 64% for carpet treatment 2 (CT-2). Differences in the carpet fibers of each product may have

also contributed to the overall removal efficiency of PFCAs. No significant difference in the

reduction of PFCAs was observed when detergent was added to the carpet cleaning machine. With

the commercial steam cleaner using a commercial detergent, a slight improvement was noted

during one experiment in which an effective removal of more than 70% of total PFCA was

obtained. However, the difference was not statistically significant.

Further work is needed in the following areas to better understand human exposure to PFCAs from

treated carpeting: (1) PFCA transfer mechanisms from carpets to indoor air, household surfaces,

and dust; (2) the relationship between PFCA-treated carpet and inhalation exposure with regard to

particle resuspension; (3) determination of the significance of dermal exposure; and (4) effective

risk management measures for reducing PFCA levels in houses with PFCA-treated carpet. It is also

recommended that market monitoring be continued to determine if all the carpet-treatment

products on today’s market are virtually PFCA-free.

47

## Acknowledgments

We thank Andrew Lindstrom and Mark Strynar of the EPA National Exposure Research

Laboratory for technical consultation and assistance; Robert Wright and Joan Bursey of the EPA

National Risk Management Research Laboratory and Libby Nessley of ARCADIS for QA support.

48

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51

## Appendix A: Data

Data for total PFCA content in carpet fibers for all the experiments are presented below.

Both individual carpet fiber samples and composite fiber samples, five per type, were

collected at five stages of each experiment. These stages included before the application of

a carpet treatment solution, after the application of a carpet treatment solution, and after

each of three rounds of cleaning with a carpet cleaning machine. The PFCA concentrations

(as mean ± standard deviation) in composite carpet fiber samples for Experiments 1

through 9 are presented in Tables A1- A9. Averaged PFCA concentrations at each step for

individual samples are not presented, but post-application data are given in Tables A10­

A18 to demonstrate the lower data quality for individual samples and to give an indication

of application uniformity, as discussed previously in Section 2.7.1.

In the following tables, each experiment is coded with the parameters of the experiment, as

presented in Table 2.3. The resulting code is presented as: Type of carpet: R = residential or

C = commercial; carpet stain-protection treatment: 1 or 2; carpet cleaning machine: 1 or 2;

and carpet detergent: 0 = no detergent, 1, or 2 [i.e., Experiment 1 (C-1-2-0) = Commercial

carpet, CT1, CM1, and no detergent]. BDL indicates that a result was below the instrument

detection limit of 0.2 ng/mL, while NR indicates that data could not be reported because

the results did not meet data quality requirements or were not obtained. Italicized values

indicate that the results are above the highest calibration concentration of 100 ng/mL.

PFTeDAwas not found above the practical quantification limit (PQL) and, therefore, was

not reported.

Data highlighted in bold font did not pass one or more of the QAPP-stated MQOs, but they

passed the relaxed MQOs of ± 30% established for this project.

A-1Table A.1. Average extractable PFCAs (ng/g) and percent of original amount removed in composite carpet fiber samples at eachexperimental stage for Experiment 1 (C-1-2-0).Pre-Applicationn=5Post-Applicationn=3Post-Cleaning 1n=2Post-Cleaning 2n=5Post-Cleaning 3n=4Total PFCAremoval, %PFBA-C4BDL63.4 ± 1355.6 ± 6.652.3 ± 2.849.5 ± 1.822%PFPeA-C5BDL55.1 ± 1082.7 ± 9.243.2 ± 3.039.3 ± 1.129%PFHxA-C6BDL399 ± 91349 ± 46310 ± 9.624 ± 1729%PFHpA-C7BDL1150 ± 2011530 ± 1401000± 57819 ± 7728%PFOA-C87.5 ± 1.0809 ± 126828 ± 89560 ± 17450 ± 3944%PFNA-C9BDL934 ± 1181030 ± 155864 ± 69703 ± 8925%PFDA-C10BDL514 ± 88363 ± 8.9446 ± 37373 ± 6328%PFUnDA-C11BDL382 ± 94227 ± 6.1413 ± 25373 ± 423%PFDoDA-C12BDL235 ± 66201 ± 10195 ± 8.5190 ± 3119%PFTrDA-C13BDL(NR)71.8 ± 1.191.6 ± 6.673.4 ± 10(NR)Total PFCAs7.5 ± 1.04540 ± 8014740 ± 4373980 ± 1353350 ± 36426%A-2Table A.2. Average extractable PFCAs (ng/g) and percent of original amount removed in composite carpet fiber samples at eachexperimental stage for Experiment 2 (C-2-2-0).Pre-Applicationn=5aPost-Applicationn=5Post-Cleaning 1n=3Post-Cleaning 2n=4Post-Cleaning 3n=4Total PFCAremoval, %PFBA-C4BDL(NR)(NR)(NR)(NR)(NR)PFPeA-C5BDL73.2 ± 4.835.4 ± 4.026.8 ± 2.427.0 ± 2.363%PFHxA-C6BDL411 ± 41158 ± 4.4115 ± 15122 ± 1270%PFHpA-C7BDL2520± 901340± 18916 ± 99962 ± 6862%PFOA-C8BDL1480± 140744 ± 68492 ± 78495 ± 3767%PFNA-C9BDL1980± 1131060± 86602 ± 85591 ± 5170%PFDA-C10BDL1090± 81610 ± 47377 ± 74391 ± 3464%PFUnDA-C11BDL549 ± 29287 ± 7.7191 ± 31227 ± 2859%PFDoDA-C12BDL488 ± 60271 ± 6.7207 ± 45198 ± 2159%PFTrDA-C13BDL(NR)154 ± 1498.8 ± 8.6105 ± 11(NR)Total PFCAsBDL8580 ± 4714660 ± 2343030 ± 4243120 ± 25264%aRecovery standards for these samples exceeded the measurement quality objective (MQO) but data were all BDL and presented for completeness.A-3Table A.3. Average extractable PFCAs (ng/g) and percent of original amount removed in composite carpet fiber samples at eachexperimental stage for Experiment 3 (R-1-1-0).Pre-Applicationn=3Post-Applicationn=2Post-Cleaning 1n=3Post-Cleaning 2n=3aPost-Cleaning 3n=3aTotal PFCAremoval, %PFBA-C4BDL135 ± 2995.5 ± 2.883.6 ± 7.959.0 ± 1156%PFPeA-C5BDL112 ± 1573.2 ± 2.862.1 ± 3.148.1 ± 8.957%PFHxA-C6BDL524 ± 53309 ± 14189 ± 9.1159 ± 2770%PFHpA-C7BDL716 ± 84483 ± 46342 ± 26298 ± 5658%PFOA-C8BDL384 ± 16290 ± 18249 ± 14232 ± 3640%PFNA-C9BDL447 ± 23315 ± 15283 ± 13278 ± 4838%PFDA-C10BDL257 ± 11187 ± 15127 ± 5.4106 ± 1959%PFUnDA-C11BDL279 ± 10225 ± 15159 ± 9.1155 ± 2544%PFDoDA-C12BDL197 ± 26143 ± 0.92112 ± 6.299.8 ± 1849%PFTrDA-C13BDL136 ± 15107 ± 1.782.1 ± 5.982.2 ± 9.539%Total PFCAsBDL3190 ± 2362230 ± 6.11690 ± 811520 ± 25552%aRecovery standards for these samples were between 45-70% but data included for completeness.A-4Table A.4. Average extractable PFCAs (ng/g) and percent of original amount removed in composite carpet fiber samples at eachexperimental stage for Experiment 4 (R-1-2-0).Pre-Applicationn=5Post-Applicationn=4Post-Cleaning 1n=5Post-Cleaning 2n=5Post-Cleaning 3n=3Total PFCAremoval, %PFBA-C4BDL55.1 ± 3.935.7 ± 4.0BDLBDL100%PFPeA-C5BDL53.0 ± 1.641.0 ± 5.5BDLBDL100%PFHxA-C6BDL413 ± 22334 ± 43BDLBDL100%PFHpA-C70.821 ± 1.4668 ± 24564 ± 36381 ± 21319 ± 9.752%PFOA-C8BDL349 ± 28292 ± 16273 ± 14256 ± 3.627%PFNA-C9BDL367 ± 5.3303 ± 23303 ± 15302 ± 8.918%PFDA-C10BDL177 ± 14156 ± 14139 ± 13139 ± 1422%PFUnDA-C11BDL195 ± 15168 ± 14165 ± 12185 ± 155%PFDoDA-C12BDL85.8 ± 1.979.2 ± 8.175.9 ± 6.373.7 ± 3.214%PFTrDA-C13BDL73.9 ± 1.666.6 ± 9.556.4 ± 6.556.7 ± 3.123%Total PFCAs0.821 ± 1.42440 ± 422040 ± 1191470 ± 621330 ± 3545%A-5Table A.5. Average extractable PFCAs (ng/g) and percent of original amount removed in composite carpet fiber samples at eachexperimental stage for Experiment 5 (R-2-2-0).Pre-Applicationn=5Post-Applicationn=5Post-Cleaning 1n=4Post-Cleaning 2n=5aPost-Cleaning 3n=5Total PFCAremoval, %PFBA-C4BDL10.8 ± 0.88BDL(NR)(NR)100%bPFPeA-C5BDL59.2 ± 4.729.8 ± 1.1(NR)(NR)50%bPFHxA-C6BDL252 ± 24143 ± 5.5BDL26.0 ± 1.789%PFHpA-C7BDL870 ± 64480 ± 29227 ± 8.1213 ± 2376%PFOA-C8BDL389 ± 6.9261 ± 15168 ± 2.8240 ± 1238%PFNA-C9BDL583 ± 40367 ± 18230 ± 10353 ± 2239%PFDA-C10BDL312 ± 48180 ± 1168.7 ± 9.749 ± 1084%PFUnDA-C11BDL229 ± 25228 ± 11177 ± 10219 ± 194%PFDoDA-C12BDL173 ± 13171 ± 9.8124 ± 5.4(NR)1%bPFTrDA-C13BDL95.0 ± 6.0(NR)(NR)(NR)(NR)Total PFCAsBDL3100 ± 3331940 ± 831060 ± 211144 ± 7063%aRecovery standards for reported data only 64% but data included for completeness.bTotal PFCA % removal as calculated from the results from the first cleaning. All others calculated from the third cleaning.A-6Table A.6. Average extractable PFCAs (ng/g) and percent of original amount removed in composite carpet fiber samples at eachexperimental stage for Experiment 6 (C-2-2-1). Re-use of carpet from Experiment 2.Pre-Applicationn=4aPost-Applicationn=5bPost-Cleaning 1n=5Post-Cleaning 2n=4Post-Cleaning 3n=2Total PFCAremoval, %PFBA-C4(NR)27.7 ± 3.421.4 ± 3.012.7 ± 1.311.5 ± 1.559%PFPeA-C527.0 ± 2.384.7 ± 9.061.3 ± 6.730.4 ± 2.133.5 ± 4.560%PFHxA-C6122 ± 12577 ± 38384 ± 40200 ± 3.2171 ± 2270%PFHpA-C7962 ± 682640± 1792010± 1761200± 39958 ± 13564%PFOA-C8495 ± 371700± 1161190± 67595 ± 30454 ± 0.1473%PFNA-C9591 ± 512330± 491480± 23615 ± 27445 ± 1581%PFDA-C10391 ± 341460± 1061000± 59415 ± 8.1276 ± 5.981%PFUnDA-C11227 ± 28(NR)438 ± 16181 ± 8.575.3 ± 6.0(NR)PFDoDA-C12198 ± 21669 ± 99377 ± 12123 ± 3871.4 ± 0.0989%PFTrDA-C13105 ± 11380 ± 16243 ± 1350.1 ± 5.440.7 ± 4.989%Total PFCAs3120 ± 25210450± 4457210 ± 2393420 ± 432540 ± 13076%aPre-Application data are the results of Post-Cleaning 3 for Experiment 2.bInitial post-application results are higher than previous experiments due to the re-use of the carpet from Experiment 2.A-7Table A.7. Average extractable PFCAs (ng/g) and percent of original amount removed in composite carpet fiber samples at eachexperimental stage for Experiment 7 (R-1-1-2). Experiments 7 and 8 considered replicate tests.Pre-Applicationn=5Post-Applicationn=5Post-Cleaning 1n=5Post-Cleaning 2n=5Post-Cleaning 3n=5Total PFCAremoval, %PFBA-C4BDL85.4 ± 4.127.5 ± 1.028.8 ± 5.519.0 ± 1.979%PFPeA-C5BDL79.9 ± 5.412.6 ± 0.4716.7 ± 1.09.11 ± 1.491%PFHxA-C6BDL537 ± 2969.9 ± 2.160.9 ± 8.829.8 ± 1.695%PFHpA-C7BDL809 ± 36276 ± 18263 ± 31163 ± 2281%PFOA-C8BDL417 ± 27311 ± 13324 ± 26220 ± 1748%PFNA-C9BDL495 ± 42436 ± 39516 ± 53430 ± 3213%PFDA-C10BDL288 ± 20142 ± 29159 ± 2379.0 ± 4.472%PFUnDA-C11BDL258 ± 17214 ± 32281 ± 39247 ± 204%PFDoDA-C12BDL83.0 ± 6.447.5 ± 3.160.7 ± 7.247.6 ± 3.545%PFTrDA-C13BDL(NR)(NR)62.3 ± 1153.2 ± 5.1(NR)Total PFCAsBDL3110 ± 1361580 ± 1231770 ± 2341300 ± 9758%A-8Table A.8. Average extractable PFCAs (ng/g) and percent of original amount removed in composite carpet fiber samples at eachexperimental stage for Experiment 8 (R-1-1-2). Experiments 7 and 8 considered replicate tests.Pre-Applicationn=5Post-Applicationn=5Post-Cleaning 1n=5Post-Cleaning 2n=5Post-Cleaning 3n=4Total PFCAremoval, %PFBA-C4BDL78.1 ± 3.530.6 ± 1.620.3 ± 1.815.5 ± 0.7080%PFPeA-C5BDL63 ± 2.522.9 ± 1.117.5 ± 1.513.1 ± 0.7679%PFHxA-C6BDL384 ± 1676.4 ± 9.349.3 ± 4.534.2 ± 1.591%PFHpA-C7BDL904 ± 28343 ± 25320 ± 21241 ± 1073%PFOA-C8BDL548 ± 10314 ± 21347 ± 30310 ± 1543%PFNA-C9BDL482 ± 32394 ± 22340 ± 25340 ± 2130%PFDA-C10BDL234 ± 4.9148 ± 1584.8 ± 6.884.2 ± 3.864%PFUnDA-C11BDL1620± 911240± 1321150± 1021250± 7323%PFDoDA-C12BDL63.2 ± 0.5958.2 ± 6.950.4 ± 0.3049.9 ± 3.520%PFTrDA-C13BDL49.8 ± 6.859.8 ± 4.449.3 ± 3.650.5 ± 3.6-1%Total PFCAsBDL4430 ± 1422680 ± 2182370 ± 2092390 ± 11146%A-9Table A.9. Average extractable PFCAs (ng/g) and percent of original amount removed in composite carpet fiber samples at eachexperimental stage for Experiment 9 (R-2-2-1). Re-use of carpet from Experiment 5.Pre-Applicationn=5aPost-Applicationn=5Post-Cleaning 1n=1Post-Cleaning 2n=5Post-Cleaning 3n=3Total PFCAremoval, %PFBA-C4(NR)9.29 ± 0.7472.84 ± 0.583.24 ± 2.765%PFPeA-C5(NR)56.8 ± 2.53420.5 ± 0.508.56 ± 0.5584%PFHxA-C626.0 ± 2.0296 ± 6.59845.0 ± 0.9627.7 ± 0.5591%PFHpA-C7213 ± 231060± 37624415 ± 11199 ± 1881%PFOA-C8240 ± 12607 ± 26370263 ± 60236 ± 8.461%PFNA-C9353 ± 22835 ± 33522368 ± 18304 ± 3264%PFDA-C1049.0 ± 10328 ± 25173113 ± 24137 ± 3758%PFUnDA-C11219 ± 19377 ± 17314241 ± 12193 ± 1279%PFDoDA-C12(NR)286 ± 11208141 ± 2285 ± 2670%PFTrDA-C13(NR)(NR)15988.9 ± 2772.9 ± 20(NR)Total PFCAs1144 ± 703840 ± 2525101700 ± 1071190 ± 12369%aPre-Application data are the results of Post-Cleaning 3 for Experiment 5.A-10Table A.10. Average extractable PFCAs (ng/g) post-application in individual carpet fiber

samples for Experiment 1 (C-1-2-0).

Post-Application

n=5 Standard Deviation

n=5

PFBA-C4 63.8 67.5

PFPeA-C5 57.1 61.9

PFHxA-C6 324 287

PFHpA-C7 977 818

PFOA-C8 684 544

PFNA-C9 794 629

PFDA-C10 479 398

PFUnDA-C11 341 270

PFDoDA-C12 213 166

PFTrDA-C13 179 152

Total PFCAs 4110 3390

Table A.11. Average extractable PFCAs (ng/g) post-application in individual carpet fiber

samples for Experiment 2 (C-2-2-0).

Post-Application

n=5 Standard Deviation

n=5

PFBA-C4 23.6 4.3

PFPeA-C5 94.9 31

PFHxA-C6 515 117

PFHpA-C7 2960 472

PFOA-C8 1680 274

PFNA-C9 2310 344

PFDA-C10 1300 190

PFUnDA-C11 619 109

PFDoDA-C12 472 60

PFTrDA-C13 245 44

Total PFCAs 10220 1610



### A-11Table A.12. Average extractable PFCAs (ng/g) post-application in individual carpet fiber

samples for Experiment 3 (R-1-1-0).

Post-Appl ication

n=5 Standard Deviation

n=5

PFBA-C4 112 27

PFPeA-C5 98.9 28

PFHxA-C6 490 134

PFHpA-C7 634 154

PFOA-C8 355 85

PFNA-C9 445 97

PFDA-C10 240 56

PFUnDA-C11 245 34

PFDoDA-C12 169 23

PFTrDA-C13 126 16

Total PFCAs 2920 640

Table A.13. Average extractable PFCAs (ng/g) post-application in individual carpet fiber

samples for Experiment 4 (R-1-2-0).

Post-Application

n=4 Standard Deviation

n=4

PFBA-C4 63.9 13

PFPeA-C5 56.9 13

PFHxA-C6 413 83

PFHpA-C7 730 115

PFOA-C8 407 45

PFNA-C9 384 68

PFDA-C10 203 15

PFUnDA-C11 200 41

PFDoDA-C12 108 18

PFTrDA-C13 85.0 11

Total PFCAs 2650 392



### A-12Table A.14. Average extractable PFCAs (ng/g) post-application in individual carpet fiber

samples for Experiment 5 (R-2-2-0).

Post-Appl ication

n=5 Standard Deviation

n=5

PFBA-C4 12.0 1.7

PFPeA-C5 67.1 9.8

PFHxA-C6 273 59

PFHpA-C7 906 182

PFOA-C8 421 104

PFNA-C9 564 147

PFDA-C10 336 56

PFUnDA-C11 243 53

PFDoDA-C12 192 41

PFTrDA-C13 102 22

Total PFCAs 3120 663

Table A.15. Average extractable PFCAs (ng/g) post-application in individual carpet fiber

samples for Experiment 6 (C-2-2-1). a

Post-Application

n=5 Standard Deviation

n=5

PFBA-C4 37.2 11

PFPeA-C5 158 74

PFHxA-C6 672 171

PFHpA-C7 3090 660

PFOA-C8 1920 424

PFNA-C9 2670 602

PFDA-C10 1660 264

PFUnDA-C11 721 115

PFDoDA-C12 681 148

PFTrDA-C13 493 125

Total PFCAs 12100 2580

a Re-use of carpet from Experiment 2.



### A-13Table A.16. Average extractable PFCAs (ng/g) post-application in individual carpet fiber

samples for Experiment 7 (R-1-1-2). Experiments 7 and 8 considered replicate tests.

Post-Application

n=4 Standard Deviation

n=4

PFBA-C4 113 51

PFPeA-C5 95.2 46

PFHxA-C6 524 86

PFHpA-C7 753 141

PFOA-C8 365 69

PFNA-C9 460 91

PFDA-C10 272 47

PFUnDA-C11 293 33

PFDoDA-C12 69.5 51

PFTrDA-C13 44.2 12

Total PFCAs 2960 586

Table A.17. Average extractable PFCAs (ng/g) post-application in individual carpet fiber

samples for Experiment 8 (R-1-1-2). Experiments 7 and 8 considered replicate tests.

Post-Application

n=5 Standard Deviation

n=5

PFBA-C4 79.9 15

PFPeA-C5 63.3 15

PFHxA-C6 342 86

PFHpA-C7 674 157

PFOA-C8 416 100

PFNA-C9 471 100

PFDA-C10 253 62

PFUnDA-C11 243 43

PFDoDA-C12 61.0 13

PFTrDA-C13 49.9 10

Total PFCAs 2650 589



### A-14Table A.18. Average extractable PFCAs (ng/g) post-application in individual carpet fiber

samples for Experiment 9 (R-2-2-1). a

Post-Application

n=4 Standard Deviation

n=4

PFBA-C4 7.52 5.1

PFPeA-C5 51.7 18

PFHxA-C6 271 68

PFHpA-C7 965 269

PFOA-C8 585 169

PFNA-C9 801 234

PFDA-C10 355 88

PFUnDA-C11 369 78

PFDoDA-C12 282 67

PFTrDA-C13 136 26

Total PFCAs 3830 954

a Re-use of carpet from Experiment 5.



### A-15