EPA Review of Completed 

AEATF II Mop Study

Dermal and inhalation monitoring of 

workers mopping floors 

1

John M. Carley

Tim Leighton

Office of Pesticide Programs

Jonathan Cohen, PhD

ICF International

workers mopping floors 

with an antimicrobial product
Organization of Presentation

 Background and Context

Science Assessment

2



 Ethics Assessment
Different Questions for Completed Study

 Was the proposal appropriately amended after review?

 Responsiveness to EPA and HSRB comments?

 Approved by IIRB and CDPR?

 Was the protocol faithfully executed?

3

 Did recruiting follow the design?

 Were needed amendments properly handled?

 Did deviations compromise the research or the subjects?

 What were the results? Were the objectives achieved?

 Was the research conducted ethically?
Scope of Mop Scenario

 One of 17 AEATF II antimicrobial handler 

exposure scenarios

 Includes mopping floors with a dilute solution 

of antimicrobial product in water, and 

4

emptying each mop bucket

 Excludes pouring concentrated product into 

mop buckets and mixing with water

 Many variations

 Will be monitored as a different scenario
Mop Study: Basics

 Conducted in 3 randomly selected vacant buildings in 

Fresno, CA

 Site 1: Office building

 Site 2: Retail space (Rite Aid)

 Site 3: Meeting space (Retired Teacher’s Memorial Building)

5

 To ensure diversity of individual 

exposures, at each site one enrolled 

subject was assigned to each of six 

“Monitoring Events” (MEs), defined 

by the planned duration of mopping

1 30 - <40 min

2 40 - <50

3 50 - <60

4 60 - <70

5 70 - <80

6 80 - 90

ME Planned 

Duration
Intended Diversity Was Achieved

Site 1 Site 2 Site 3

1 30 - <40 min 31 38 38

ME Planned Actual Duration

Duration

6

2 40 - <50 45 51 49

3 50 - <60 59 63 59

4 60 - <70 67 69 69

5 70 - <80 53 79 79

6 80 - 90 85 90 89
Mop Study: Basics

 Monitored dermal and inhalation exposure of 6 subjects 

at each of 3 sites (N=18) to didecyl ammonium chloride 

(DDAC) formulated as Buckeye Sanicare Lemon Quat

 Subjects wore outer/inner dermal exposure dosimeters:

 Long pants, long-sleeved shirt, shoes, socks, and no gloves

7

 Long pants, long-sleeved shirt, shoes, socks, and no gloves

 Whole body dosimeters (WBD) underneath clothing

 Subjects also wore breathing zone OVS air samplers, 

with pump on belt

 Subjects mopped floors using a string mop and a bucket 

with wringer, and emptied spent mop water
Macro Schedule: AEATF II Mop Study

Protocol Review

Protocol Revision

Recruiting/Enrollment

2008 2009 2010

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

8

Recruiting/Enrollment

Field Monitoring

Sample Analysis

Closeout/QA/Reporting

EPA/HSRB Post-Review
Study Submission to EPA

31 Aug 10

20 Sep 10

AEATF II submits Final Report 

(MRID 48210201)

AEATF II submits Supplement 1 

(MRID 48231201)

9

21 Sep 10

30 Sep 10

18 Oct 10

AEATF II submits Supplement 2 

(MRID 48231901)

GPL submits demographic data

GPL submits e-mail responses to EPA 

questions
Documents Considered in EPA Reviews

 Primary Study Report MRID 48210201

 Supplement 1 MRID 48231201

 Supplement 2 MRID 48231901

 Demographic Data Spreadsheet “Subject Info all 32”

10

 EPA Science & Ethics Review of Mop Protocol (10 Mar 08)

 HSRB 25 Jun 08 Report of April 08 review of Mop Protocol

10
Scope of Revisions & Amendments

 Protocol revisions of 26 Feb 09 addressed most EPA 

and HSRB comments

 Amendments

1. Refine criteria for site selection

2. Clarify details in protocol; Revise consent form

11

3. Permit enrollment of subjects one-by-one

4. Add newspaper advertisements

5. Randomize assignment of enrolled subjects to MEs

6. Revise specification for analytical phase

7. Change Field Study Coordinator and Associate; 

Revise consent form to conform
Science Assessment

AEATF II Mop Study

12

Tim Leighton

Office of Pesticide Programs

Jonathan Cohen, PhD

ICF International

October 28, 2010
Overview

 Study Objective

 Responsiveness to EPA and HSRB Comments

 Protocol Deviations

 DDAC Residue Removal Efficiency Study

13

 Sectioning of WBD (Inner & Outer)

 Dermal Unit Exposures Represent 3 Clothing Configurations

 Summary of Key Study Parameters

 QA/QC Results

 Statistical Analysis 

 Conclusions 
Study Objective

 Collect mopping exposure data in which the 

upper and lower 95% confidence limits will 

be no more than 3-fold (K=3) higher or lower 

than the geometric mean, arithmetic mean, 

14

and 95th percentile of the unit exposures
Responsiveness to EPA Comments

 Redefine the scenario to include disposing of 

spent mop water

 Done in revised protocol of Feb 09

15

 Provide data on recovery efficiency of handwash/face-wipe methods for DDAC

 Provided existing study on efficiency of DDAC residue 

removal from hands
Responsiveness to HSRB Comments

 Consider repeat measurements

 Trade-off of knowledge about within-worker variability for 

more samples of between-worker variability

 Use longer monitoring duration

16

 Additional industry information indicates 90 minutes of 

mopping per day represents the reasonable upper range

 Consider defining ME by AaiH vs duration

 Best information available for mopping is based on duration

 Review proportionality between exposure and AaiH

 AEATF II deferred to EPA
Protocol Deviations

 22 reported protocol deviations, including

 Air sampling related issues

 Light levels not monitored at sites

 Participant re-mopped an area previously mopped

17

 Participant re-mopped an area previously mopped

 Chain of custody documentation lost for 1 sample 

 1 unreported deviation (change in type of 

mop bucket)

 None of the deviations negate the use of the 

exposure results 
Proposed Brite 6185 EZMT Mop Bucket 

with 6127-01 Wringer

 “EZMT” foot pedal permits user 

18

to empty bucket into floor drain 

without lifting it

 This product discontinued by 

manufacturer in 2006 in favor of 

a bucket with baffles to reduce 

sloshing
35-Qt SplashGuardTM 

Mop Bucket used in 

Mop Study

 CON 335-3YW Bucket

19

 CON SW7YW Down-Press 

Wringer

No foot pedal for emptying 

without lifting

Internal baffles to reduce 

sloshing
DDAC Residue Removal Efficiency Study

 MRIDs 47214801, 48270301; Pre-Rule study

 Removal efficiency study summary

 Hand fortified (pipette to palm) with 5 or 100 ug/50uL/hand; 

n=10 for each fortification level

 Allowed to dry for 30 min, then washed/rinsed with 50% IPA in water

20

 Residues remaining after initial hand wash wiped from hand using 

dressing sponges moistened with 50% IPA in water

 Mop study hand wash and face/neck wipe procedures similar

 Removal efficiencies

 Hand wash = ~90%; Used to correct mop hand residue results

 Hand wipes = ~60%; Used to correct mop face/neck residue results
Sectioning of WBD (inner & outer)

Rear Torso

Front Torso

21

Upper Leg

Lower leg

Upper Arm

Lower Arm
Dermal Unit Exposures Represent 3 Clothing Configurations

 Study participants wore long pants, long-sleeved shirts, 

shoes/socks, no gloves over WBDs

 For each ME, residues were analyzed from both outer clothing 

and inner WBD, sectioned by body part

 Clothing configurations that can be estimated for each ME:

22

(1) long pants, long-sleeved shirt [shoes/socks, and no gloves]

(2) long pants, short-sleeved shirt [shoes/socks, and no gloves]

(3) short pants, short-sleeved shirt [shoes/socks, and no gloves]

 Estimates for “shorts” are obtained by adding the inner and 

outer lower arm (short-sleeved shirt), or by adding the inner 

and outer lower leg (short pants)
Parameter Low High Mean

Pounds AI Handled 0.00308 0.0183 0.00634

Mopping Duration (min) 31 90 62

Summary of Key Study Parameters

23

Mopping Duration (min) 31 90 62

Area Mopped (ft

2

) 3,324 14,191 5,516

No. Buckets Used 2 6 4

No. Gallons Applied ~1 5.5 ~2

DDAC Concentration 

(% AI) 0.025 0.035 0.029
QA/QC Results

 Controls

 All lab and field blanks were < LOQ

Sample LOQ

Air 10 ng

Neck/face 50 ng

Hands 1 ug

WBD sections 3 ug

24

 Laboratory Recoveries

 Range for mean ± std for all 3 clusters 95±4% to 113±3% 

 Field Recoveries

 Range for mean ± std for all 3 clusters 91±8% to 109±8%

 Field recoveries were used to correct field samples (dosimeters)

WBD sections 3 ug

Socks 1 ug
Statistical Analysis–Unit Exposures (UE)

 3 methods were used to estimate UEs

 Empirical estimates

 Simple random sample (SRS)

25

 Mixed model

 Mixed model selected to best represent the 

UE results
Arithmetic 

Mean

95th 

Percentile

Long pants/long-sleeves, 

shoes/socks, no gloves

23.2 

(17.4, 31.4)

50.8 

(33.3, 77.3)

Unit Exposures (UE) for Mopping Scenario

Exposure 

Route Clothing

AEATF II (n=18)

26

shoes/socks, no gloves (17.4, 31.4) (33.3, 77.3)

Long pants/short-sleeves, 

shoes/socks, no gloves

26.3 

(20.3, 34.6)

54.7 

(37.2, 80.3)

Short pants/short-sleeves, 

shoes/socks, no gloves

82.1 

(55.1, 125.5)

215 

(124, 373)

Inhalation 

(μg/m

3

/lb ai) Breathing zone

52.4 

(27.0, 105.7)

130 

(54.8, 318)

Dermal 

(mg/lb ai)
Was the Sample Large Enough?

 The benchmark objective of 3-fold relative 

accuracy (K ≤ 3) was met for the mixed-model 

results using the 3 cluster x 6 ME study design

 Relative accuracy (K) ranged from 1.3 to 1.7 for the 

27

mixed model results

 K <3 indicates enough samples (n=18) were 

collected to satisfy EPA’s needs

 No additional mop MEs are needed
Intra-Cluster Correlation (ICC)

 Based on analogy to earlier studies for similar 

tasks, an estimated ICC of 0.3 was used to 

determine the number of clusters and MEs in 

the study design 

28

 The ICC calculated from this mop study is 0 

 This indicates that individual behavior affects 

exposure more than does building type or floor 

configuration
Proportionality of Exposure to AaiH

 Proportionality between exposure and 

AaiH is an assumption EPA uses in 

handler exposure assessments

29
Does the Mop Study Support or Confound 

the Assumption of Proportionality?

 The Mop Study provides: 

 Evidence of proportionality between dermal exposure and AaiH 

 No evidence of proportionality between inhalation exposure and 

30

AaiH

 Minimal exposure was expected from this mopping scenario 

(low VP and low potential for aerosols) and monitored 

exposure was very low (mean 0.000263 mg/m3)

 We did not learn anything that would lead us to abandon 

the assumption of proportionality
Limitations on Data Generalization

 Mop study population is not a true random sample 

 Assumes exposure is independent of location

 Bias of volunteer pool unknown

Statistical inference from these results to the 

31



universe of moppers is not justifiable
EPA Plan for Use of Mop Study Data

 Use unit exposure data generically to estimate 

potential exposure to low- or moderate-volatility 

pesticides use in mopping scenarios

 String mop is worst case, representing all mops, including 

RTU, sponge, or microfiber mops

32

 Dermal UEs available for various clothing configurations 

 UEs normalized by AaiH

 Use chemical-specific hazard and dermal absorption 

data to estimate internal dose and risk
Example: New AI with Low Volatility

 Assume product has these relevant characteristics 

 Acute toxicity profile is consistent with short-sleeved shirts with long 

pants, no gloves

 10% active ingredient in concentrated product

33

 Dilution rate 0.5 ounce per gallon water, from automatic dispenser

 Estimate daily exposure = UE x AaiH

 Dermal UE from long pants/short-sleeved shirt, socks, no gloves

 Inhalation UE = air concentration (mg/m3/pound AI)

 AaiH = 0.5 fl oz * 1 gal/128 fl oz * density 8.34 lb/gal * 5 gallons/day 

* 0.1 ai in concentrated product
Calculation of AaiH

 AaiH =

 Volume of concentrated product in fluid ounces, 

converted first to gallons, and then to weight

 * Number of gallons mopped per day

34

 * Concentration of AI in product

 AaiH = 0.5 fl oz/gal * 1 gal/128 fl oz * 

density 8.34 lb/gal * 5 gallons/day * 0.1 ai
Conclusions

 Study results are sound enough to support 

estimates of dermal and inhalation unit 

exposures in the mopping scenario

35

 Enough samples were collected: no additional 

mop MEs are required 

 Data limitations must be acknowledged in 

assessments
Ethics Assessment

AEATF II Mop Study

36

John M. Carley

Human Research Ethics Review Officer

Office of Pesticide Programs

October 28, 2010
Overview

 Responsiveness to protocol reviews

 IRB oversight

 Recruiting and subject demographics

37

 Deviations of potential ethical significance

 Completeness of documentation

 Substantive acceptance standards

 Findings 

 Conclusions
Responsiveness to EPA Comments

 Better provision for interviewing and 

consenting Spanish-speaking subjects

 References to translators replaced by references 

to bilingual investigators in protocol of 26 Feb 09

38

 Express “normal business hours” in local time

 Changed to Pacific Time in revised consent form, 

ESBOR, and flyer
Responsiveness to HSRB Comments

 Consider using a tracer 

rather than pesticide

 Ensure CF is readable; 

simplify

 Used pesticide, per EPA 

advice

 Negligible change in 

readability

39

simplify

 Explain how community will 

be engaged/involved

 Ensure Spanish translations 

are in appropriate dialect

readability

 Revised in protocol; planned 

meetings with employers did 

not take place

 All translations done by CA 

translator, part of research 

team
IRB Oversight

 Initial protocol reviewed by convened IIRB, 

Inc. in Jan 08

 All subsequent IIRB, Inc. reviews conducted 

40

under expedited procedures, without minutes 

or other records

 Investigators complied fully with IIRB, Inc., 

procedures and requirements
Accounting for Recruiting Processes

24-Apr-09 Janitorial Services Companies Identified 322

| Janitorial Services Contacted ?

| Janitorial Services Agreeing to Post Flyer 65

13-Jul-09 Callers Responding to Flyers 21

Amendment 3 Subjects Enrolled 7

Amendment 4 Callers Responding to Newspaper Ads ~35

41

Amendment 4 Callers Responding to Newspaper Ads ~35

| Enrolled from Newspaper Ads 25

24-Jul-09 Total Subjects Enrolled 32

Withdrawn: Sensitive to Alcohol Rinse 2

Total Subjects Randomized 30

Withdrawn: Moved Away 1

Randomized to MEs 18

Randomized to Alternate MEs 6

Other alternates 5
Recruiting Summary

 Recruiting process was equitable, and free of 

coercion or undue influence

 Recruiting was conducted consistent with the 

42

protocol, at each stage of amendment

 Subject recruiting and selection processes were 

consistent with EPA’s policy direction to 

incorporate random elements whenever feasible
Subject Demographics

All Enrolled Subjects Monitored Subjects

Male 15 (47%) 10 (56%)

Female 17 (53%) 8 (44%)

English 20 (63%) 11 (61%)

Spanish 12 (37%) 7 (39%)

Sex

Language

43

Spanish 12 (37%) 7 (39%)

3 mos - 40 yrs 3 mos - 40 yrs

8.8 yrs 11.1 yrs

18 - 53 18 - 53

36.8 yrs 38.1 yrs

 "Excellent" 18 (56%) 10 (56%)

 "Good" 12 (38%) 7 (39%)

 "Fair" 2 (6%) 1 (6%)

Requested Results 25 (78%) 15 (83%)

Health

Range of Experience

Mean Experience

Age Range

Mean Age
Deviations of Ethical Significance

 Reported deviations:

 Omitted/shortened rest breaks

 Photos showing subjects’ faces at one site

44

 Unreported deviations:

 Enrollment of 2 subjects with self-described “fair” 

health

 Creation and retention of additional records linking 

subject names to ID codes
Completeness of Documentation—1

 Initial “Final Report” (MRID 48210201)

 Significant omissions

• Protocol with tracked changes

• Documentation of IRB approvals

45

 Appendices Q and R full of irrelevant, duplicative 

material, completely unindexed

 Supplement 1 (MRID 48231201)

 Substantively complete

 Irrelevant, duplicative material deleted from 

Appendices Q and R; both appendices fully indexed
Completeness – 2 

 Other deficiencies:

 Rationale for defining MEs by duration (provided in 

Supplement 2—MRID 48231901)

 Subject demographics (provided in spreadsheet 30 Sep 10)

 Accounting for pre-enrollment recruiting process (provided in 

46

 Accounting for pre-enrollment recruiting process (provided in 

email 18 Oct 10)

 IIRB procedures and roster (provided directly by IIRB, Inc.)

 Requirements of §26.1303 substantially satisfied
Substantive Acceptance Standards

 40 CFR §26.1703

 Prohibits reliance on data involving intentional exposure of 

pregnant or nursing women or of children

 40 CFR §26.1705

47

 Prohibits reliance on data unless EPA has adequate 

information to determine substantial compliance with 

subparts A through L for 40 CFR 26

 FIFRA §12(a)(2)(P)

 Makes it unlawful to use a pesticide in human tests without 

fully informed, fully voluntary consent
Findings

 All subjects were at least 18; pregnant or nursing 

women were excluded; all females were tested for 

pregnancy

 No noteworthy deficiencies in the ethical conduct of 

the research

48

 Protocol was faithfully executed, and amended when 

needed; minor deviations did not compromise safety 

or consent of subjects

 Subjects were fully informed and their consent was 

fully voluntary, without coercion or undue influence
Conclusion

 Available information indicates that the 

AEATF II Mop Study was conducted in 

substantial compliance with subparts K 

and L of 40 CFR part 26

49
AEATF II Mop Study: Charge Questions

a. Was the research reported in the Antimicrobial Exposure Assessment 

Task Force II (AEATF–II) completed study report AEA03 and 

associated supplemental reports faithful to the design and objectives of 

the protocol and governing document of AEATF-II? 

b. Has the Agency adequately characterized, from a scientific perspective, 

50

b. Has the Agency adequately characterized, from a scientific perspective, 

the limitations on these data that should be considered when using the 

data in estimating exposure of those who apply antimicrobial floorcleaning products with mop and bucket? 

c. Does available information support a determination that the study was 

conducted in substantial compliance with subparts K and L of 40 CFR 

Part 26?