OPTIONS FOR REVISING CEB 

S METHOD

FOR

SCREENING-LEVEL

ESTIMATES OF DERMAL EXPOSURE

FINAL REPORT

JUNE, 2000

Chemical Engineering Branch

Economics, Exposure and Technology Division
Options for Revising CEB Dermal Method - Final 06/00

i

SUMMARY

The purpose of this report is to present options and a recommendation for revising the

Chemical Engineering Branch s (CEB s) Dermal Exposure Assessment method based on the

results of the 1996 peer reviewed research titled: Occupational Dermal Exposure Assessment -

A Review of Methodologies and Field Data, as well as other recent dermal exposure studies. 

CEB s current method for dermal exposure assessment presents factors for calculation of

potential dermal exposure based on: 

 " an estimate of the skin surface area of the hands

 " values of the quantity of material typically remaining on the skin derived

from a laboratory study ( Q  value)

 " judgements as to the types of common industrial activities that could be

associated with the available data

 " judgements on whether the potential for exposure for an activity is best

characterized as routine  or incidental 

 " judgements on the number of hands (total skin surface area potentially

exposed) for various worker activities 

The scope of this report was on the first three aspects of the CEB method for dermal

assessments mentioned above. It does not address the judgements regarding routine or incidental

or total skin surface area. Those are worthwhile topics to address as part of the ongoing effort to

refine the CEB dermal method but were not part of the scope of this effort.

Key findings and recommendations from the peer reviewed research report and other

recent studies judged to be applicable to revising the CEB method are listed below.

6. Revise estimate of skin surface area of the hand (Recommendation in peer

reviewed research report).

7. Q  values from 1984 Versar report (used in current CEB method) were updated

in 1992 final report

8. Available data indicate a maximum dermal retention of 10 mg/cm2 for solids and 

4 to 10 mg/cm2 for liquids (Conclusion in Peer Reviewed Research report)

9. Q  values for liquids derived from field monitoring studies (albeit pesticide

handling) are available from PHED (Pesticide Handlers Exposure Database). 

(Data analyzed and presented in peer reviewed research report).

10. Field monitoring data for solids is now available for assessment of exposure in

solids handling activities. (Current CEB method uses laboratory data for liquids

in assessments of exposure in solids handling activities). 

11. High quality data is available from PMN dermal monitoring study (non-pesticide

field data for a liquid)

12. Use data from the other parts of the body with the current CEB method
Options for Revising CEB Dermal Method - Final 06/00

ii

(Recommendation of the Peer Reviewed Research).

13. Guidance for qualitative assessments of dermal exposure is available to be

incorporated into formal CEB Dermal Method. (Guidance in CEB Manual (CEB,

1991) used historically by CEB in PMN review program).

Nine different options were developed ranging from doing nothing to an option which

incorporated all of the key findings and recommendations mentioned above. The initial 

recommended option was the option which incorporated all. This option was presented to CEB

for review. The results of this review resulted in the following modifications to the

recommended option.

1. The terms routine  and incidental branch are left in the CEB method for now

but it will be noted that they reflect typical CEB judgements of the likelihood of

contact for the example activities.

2. The term activity  used in CEB Manual and options is changed to Type of

Contact  and each type of contact will have a unique name to help CEB

distinguish between the assumptions associated with each.

3. The highest values in ranges with term up to  will be used since this table is for

screening-level purposes.

4. The methodology for assessing exposure to other parts of the body needs more

development and input from risk assessors so it won t be included as part of the

CEB method for now. 

The proposed revised CEB method for screening-level assessments of dermal exposure

consists of 2 tables: Hands (liquids and solids) and qualitative assessments. These tables are

presented below. 
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Table 1: Factors for Screening-Level Assessments of Dermal Exposure to the Hands

Type of Contact1 Typical Examples

S

2

(cm2)

Q

3

(mg/cm2)

Resulting Dermal

Contact (mg)

Routine, direct

handling of solids -

2 hands

" Filling/dumping containers

 of powders, flakes, granules

" Weighing powder/

 scooping /mixing (i.e., dye

 weighing)

" Handling wet or dried material

in a filtration and drying process 

up to 31004

Routine co ntact with

surfaces - 2 hands -

solids

" Handling bags of solid

materials (clo sed or empty)

up to 11004

Routine immersion,

2 hands - liquids

" Handling wet surfaces

" Spray painting

840 1.3 - 10.3 up to 8,700

Routine co ntact, 

2 hands - liquids

" Maintenance

" Manual cleaning of equipment

" Filling drum w ith liquid

840 0.7 - 2.1 up to 1,800

Incidental co ntact, 2

hands - liquids

" Connecting transfer line 840 0.7 - 2.1 up to 1,800

Incidental co ntact, 1

hand - liquids

" Sampling

" Ladling liquid /bench sca le

 liquid transfer

420 0.7 - 2.1 up to 900

Notes:

1- The term s routine  and incidental  reflect typical CE B judgements on likelih ood of co ntact for the exa mple

activities.

2 - Values of the skin surface area of the hands taken from: EPA Exposure Factors Handb ook, 1997 and are the

mean values for men

3 - Selected ranges of Q  Values for liq uid handling activities taken from: EPA , 1992. A Labora tory Meth od to

Determine the Retention of Liquids on the Surface of Hands, Exposure Evaluation Division, Office of Pollution

Prevention and Toxic, USEPA, EPA 747-R-92-003, September, 1992.

4 - Values fo r dermal co ntact for solids h andling activities were taken fro m: Lansink, 1 996. Lan sink, C.J.M ., 

M.S.C. Breelen, J. Marqu art, and J.J. va n Hemm en: Skin Ex posure to Calcium Carbonate in the Paint Ind ustry. 

Preliminar y Mod eling of Skin E xposure L evels to Po wders Based on F ield Data (T NO Report V 96.064 ). 

Rijswijk, The Netherlands: TNO Nutrition and Food Research Institute, 1996.

Further details on derivation of this table can be found in: CEB, 2000. Options for Revising CEB s Method for
Options for Revising CEB Dermal Method - Final 06/00

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Screening-Level Estimates of Dermal Exposure. Final Report. 06/01/00.

Table 2: CEB Method for Screening-Level Assessments of Dermal Exposure - Qualitative

Assessments1

Category Dermal Assessment

- Corrosives (pH >12, pH <2) Negligible

- Materials at temperatures >140 deg. F (60 deg. C) Negligible

- Cast Solids (such as mo lded plastics)/PMN in

matrices such as extruded p ellets 

Ex. Chemical is an additive for plastics. It has been

physically mixed and incorporated into a plastic pellet

but not chem ically reacted a way.

Non-Q uantifiable (Some su rface conta ct may occu r if

manually transferred)

Work ers handling th e plastic in the form of pellets

could get su rface conta ct with the chemical additive. 

- Dry  surface coatings (e.g., fiber spin finishes) Non-Quantifiable (If manual handling is necessary and

there is an indication that the material may abrade from

the surface, quantify contact with fingers/palms as

appropriate)

- Gases/Vapors Non-Quantifiable (Some contact may occur in the

absence of protective clothing)

Notes:

1 - Reference: (CEB, 1991). Chemical Engineering Branch Manua l for the Preparation of Engineering 

Assessments, Washington, D.C.: Office of Toxic Substances, U.S. Environmental Protection Agency, 1991.

Other Guidance for Use

Screening-Level - The estimates of dermal contact presented in the table are intended for

use in screening-level assessments of the type that CEB prepares for the new chemicals program. 

They provide an estimate of potential dermal exposure and do not take into account the

protection from the use of gloves.

More Refined Assessments - If there is a need for a more refined assessment, CEB

assessors can review the studies in more detail to determine a more appropriate estimate for their

situation. However, to ensure consistency, these more refined assessments should be reviewed

and saved in a Dermal  subdirectory on the K:\Group\CEB directory.

Exposure Descriptors - Based on reviews of the applicable field data, the values reported

in Table 1 provide exposure estimates that fall in the upper end of the range and represent a

conservative estimate of exposure. For use in individual assessments, CEB exposure assessors
Options for Revising CEB Dermal Method - Final 06/00

v

will need to evaluate case-specific information and the details of the various studies cited in this

report to determine the appropriate exposure descriptors (i.e. bounding , high-end , what-if )

for their individual case. Guidance on exposure descriptors can be found in EPA, 1992. 

Exposure to Other Parts of the Body

One of the recommendations of the peer reviewed research report was to use data on

exposure to other parts of the body with the current CEB method. This resulted from review of

the available data from the literature as well as PHED that showed exposure to other parts of the

body. This was also shown in the previously mentioned dermal exposure study undertaken by a

PMN submitter. Recommended factors for estimating dermal exposure to other parts of the body

are presented in this report. These values were taken from the estimated 90th percentile

deposition from the PHED database. 

CEB believes that further development and input from risk assessors is needed before

presenting an approach for estimating exposure to other parts of the body. This area has been

identified as one of the areas for further development as part of CEB s effort to continuously

improve its assessment methodologies. The available data show that hand exposure constitutes

the majority of the total body exposure.

Part of Ongoing Effort

CEB regards the revised tables as the logical next step in development of its dermal

assessment methodology. As with all of its methodologies, improvement is an ongoing process. 

Areas that CEB plans to address in the future in addition to assessments of exposure to other

parts of the body include revisiting the judgements of routine and incidental exposure and their

application to the Exposure Based Policy and Peer review of the revised table.
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ACKNOWLEDGMENTS

The primary author of this report was Greg Macek of the Chemical Engineering Branch

(CEB). Special acknowledgment is given to Cathy Fehrenbacher, formerly of CEB, who was

project leader for the dermal research that serves as the primary basis for the recommended

revisions to the current CEB dermal method.

This report was reviewed by members of CEB and their comments have been

incorporated into the recommended option. In particular, comments from CEB staff members

Scott Prothero and John Blouin and Branch Chief, Nhan Nguyen were instrumental in

developing the recommended option. 
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TABLE OF CONTENTS

PAGE 

SUMMARY i to v

ACKNOWLEDGMENTS vi

INTRODUCTION ix

SECTION 1 - CEB S CURRENT METHOD 1.1 to 1.2

SECTION 2 - NEW INFORMATION ON DERMAL EXPOSURE 2.1 to 2.3

ASSESSMENT

SECTION 3 - OPTIONS FOR REVISING THE CEB METHOD 3.1 to 3.15

SECTION 4 - RECOMMENDATION 4.1 to 4.4

REFERENCES R-1

APPENDIX 

1. DATA FROM DERMAL EXPOSURE STUDIES USED

TO REVISED THE CEB METHOD

1.1 Pesticide Handlers Exposure Database A-2 to A-6

1.2 USEPA, 1992a. A Laboratory Method to Determine A-7 to A-8

 the Retention of Liquids on the Surface of the Hands

1.3 EPA Exposure Factors Handbook, 1997 (Final Report) A-9 to A-10

1.4 USEPA, 1992b. Exposure and Release Estimations for A-11 to A-15

Filter Press and Tray Dryer Operations Based on Pilot 

Plant Data. 
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1.5 Skin Exposure to Calcium Carbonate in the Paint Industry - A-16 to A-21

Lansink, et. al., 1996.

1.6 Worker Dermal Exposure to Trichloroketone, A-22 to A-26

Anonymous,1996

2. CEB REVIEW OF RECOMMENDED OPTION A-27 to A-30
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INTRODUCTION

The Chemical Engineering Branch (CEB) of EPA s Office of Pollution Prevention and

Toxics (OPPT) has the responsibility of preparing assessments of occupational exposure for

chemicals the EPA reviews under the Toxic Substances Control Act (TSCA). Ideally, these

assessments are based on field monitoring data for the chemical being evaluated. In the absence

of such data (almost always the case for new chemical reviews), CEB relies on data on analogous

substances, generic scenarios, regulatory standards, or models to develop estimates of potential

exposure. Two important routes of exposure that CEB considers are the inhalation and dermal

routes.

The focus of this report is on the CEB s assessments of exposure via the dermal route. 

CEB currently uses a method based on laboratory experiments that obtained estimates of the

quantity of chemical retained on a unit area of the skin for various activities. Dermal exposure

estimates are then developed by extrapolating these quantities over the total surface area of skin

exposed. 

CEB undertook research for the purpose of validating and improving its dermal method. 

Specific objectives of the research included providing a literature search of monitoring data on

dermal exposure and making recommendations to improve the CEB method based on the

literature search and evaluation. The results of the research are presented in the peer-reviewed

report, Occupational Dermal Exposure Assessment - A Review of Methodologies and Field

Data, (SAIC, 1996).

This report presents options for revising CEB s Dermal Exposure Assessment method

based on the results of that research effort as well as other recent reports related to the assessment

of dermal exposure. A review of CEB s current dermal exposure assessment method is

presented in Section 1. A summary of the SAIC report and the other recent studies that have

been published since CEB s original dermal assessment method was developed is presented in

Section 2 (More detailed summaries of the studies are provided in the appendix). Options for

revising CEB s method are presented in Section 3 and the recommended option is given in

Section 4.
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1.1

SECTION 1 - CEB S CURRENT METHOD

CEB s current method for assessing dermal exposure is described in detail in the CEB

Engineering Manual (CEB, 1991). The method provides guidance for qualitative assessment in

cases where a quantitative estimate should not be made such as for corrosive or high temperature

materials. For quantitative assessments, the following equation is used to develop estimates of

the potential dermal dose rate (amount available for absorption).

D = SQC

where: D = dermal potential dose rate, mg/day

S = surface area of contact, cm2

Q = amount retained on the skin, mg/cm2

C = concentration of chemical of concern, percent by weight

Estimates of the amount of chemical retained on the skin were derived from an

experimental study by Versar (Versar, 1984). In the Versar study, experiments were performed

to measure the amount of exposure to hands for various types of activities. Experiments were

performed on six liquids of various viscosities. The results for immersion ranged from 4.99 to

13.85 mg/cm2. The results for activities such as wiping up a spill or wiping the hands with a

contaminated cloth, and for the amount remaining when the hands were partially  wiped with a

clean cloth after immersion suggested a range of 1 to 3 mg/cm2. 

CEB made an assumption that the experimental data for liquids could also be applied to

assessments for powders. CEB then made judgements as to the type of common industrial

activities that could be associated with the activity measured by Versar. Estimates of surface

area were derived from Poppendorf and Leffingwell (1982). This resulted in the following table

which is CEB s current dermal exposure assessment method.
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1.2

Table 3: Typical Factors for Calculation of Dermal Exposure

Activity Typical Examples

S

1

(cm2)

Q

2

(mg/cm2)

Resulting Typical

Contact3 (mg)

Routine immersion,

2 hands

" Handling wet surfaces

" Filling/dumping containers

 of powders, flakes, granules

" Spray painting

1,300 5-14 6,500 to 18,200

Routine co ntact, 

2 hands

" Maintenance/manual

 cleaning of equipment

" Unloading filter cake

" Changing filter

" Filling drum w ith liquid

1,300 1-3 1,300 to 3,900

Routine co ntact, 

1 hand

650 1-3 650 to 1,950

Incidental co ntact, 2

hands

" Connecting transfer line

" Weighing powder/

 scooping /mixing (i.e., dye

 weighing)

1,300 1-3 1,300 to 3,900

Incidental co ntact, 1

hand

" Sampling

" Ladling liquid /bench sca le

 liquid transfer

650 1-3 650 to 1,950

1

Popen dorf and L effingwell 198 2. S is surface a rea of conta ct.

2Versar 1984. Q is quantity typically remaining on skin.

3These estimates also must be adjusted by the concentration of the chemical in the mixture and the percent of the

hand exposed if this is less than what would be typical. Concentrations that change over time due to evaporation or

other factors also should be accounted for.
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2.1

SECTION 2 - NEW INFORMATION ON DERMAL EXPOSURE

ASSESSMENT

Since CEB s dermal method was developed, the aforementioned research project for the

purposes of validating and improving the method has been completed, and several other reports

on dermal exposure assessment issues have become available. These are identified below along

with key information from the report that could be applied to CEB s dermal method. The report

title, author and year are provided and a summary of the key data contained in the report are

provided. A more detailed reference can be found in the reference section of this report and a

more detailed summary of the data is provided in the appendix..

1. Occupational Dermal Exposure Assessment - A Review of Methodologies and Field Data,

SAIC, 1996.

This peer reviewed research report was prepared by SAIC under contract to EPA/CEB. 

The objectives of this report were to:

 " Provide a literature search of monitoring data on dermal exposure. This included

the open literature as well as data in the Pesticide Handlers Exposure Database

(PHED) maintained by EPA s Office of Pesticides.

 " Evaluate the CEB method and revise or identify additional values and input

parameters (e.g., quantity remained on the skin, skin surface area) for predicting

dermal exposure under various exposure scenarios

 " Make recommendations to improve the CEB method based on the literature

search and evaluation

Key conclusions of the research are listed below. 

1. The CEB method currently only assesses hand exposure. The field monitoring

studies routinely included evaluation of exposure to other parts of the body, even

though hand exposure often constitutes the majority of the total body exposure 

2. The value of hand surface area used by CEB is not current.

3. The current input parameters for hand exposure using the CEB method are found

to be very similar to the PHED data. The PHED data for other parts of the body

could be used with the CEB method.
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2.2

4. Available data in the literature indicate a maximum dermal retention of 10

mg/cm2 for solids and 4 to 10 mg/cm2 for liquid.

5. The deposition approach currently used by CEB is appropriate for solid or

particulate media. The dermal absorption approach whereby a skin permeation

coefficient is used to estimate absorbed dose directly, is theoretically more

appropriate for evaluating exposure to chemicals in a liquid media.

Recommendations for improving the CEB method.

1. The EPA (1987) values for skin surface area should be used. (Note: the values for

hands and forearms were 820 and 1210 cm2 respectively).

2. Current Q  values used by CEB generate exposure estimates that fall in the upper

range of the distribution of the applicable field data. However, characterization of

CEB estimates as bounding estimates should be reevaluated for some operations.

3. Data from PHED for other parts of the body should be used with the current CEB

method.

4. The skin permeation approach is more appropriate for estimating dermal

absorption for liquid media but further development is needed before this will be a

viable approach for industrial scenarios.

Data on dermal exposure from the PHED database is provided in Appendix 1.1.

2. A Laboratory Method to Determine the Retention of Liquids on the Surface of the Hands -

EPA, 1992a

This was the final report of the work first presented in the 1984 Versar draft. The data on

the three water-based liquids from the earlier report were dropped from this report because of

uncertainties in the data. This updated report also provided a more rigorous treatment of the

earlier data on the remaining 3 liquids. The updated data is presented in Appendix 1.2.

3. EPA Exposure Factors Handbook, 1997 (Final Report)

This reference provides agency standards for exposure factors to be used in assessments. 

The mean value for the skin surface area of the hands for men based on measured data is 840

cm2, in contrast to the estimate of 1300 cm2 that CEB currently uses from the Popendorf model. 

A table of skin surface area for various parts of the body presented in the EPA Exposure Factors

Handbook can be found in Appendix 1.3.
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2.3

4. Exposure and Release Estimations for Filter Press and Tray Dryer Operations Based on Pilot

Plant Data, USEPA, 1992b. 

This study measured dermal exposure during unloading of a filter cake from a plate and

frame filter press and subsequent loading of a stationary tray dryer. Details and results are

presented in Appendix 1.4.

5. Skin Exposure to Calcium Carbonate in the Paint Industry - Lansink, et. al., 1996.

This was a dermal monitoring study conducted during the manufacture of powdered

paint. Exposures were monitored for workers involved in weighing, dumping and handling of

bags. Details and results are presented in Appendix 1.5.

6. Worker Dermal Exposure to Trichloroketone, Anonymous,1996

This report presents the results of a dermal monitoring study conducted by a PMN

submitter. Exposure was measured for chemical operators and workers involved in maintenance

activities. A detailed summary is presented in Appendix 1.6.
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3.1

SECTION 3 - OPTIONS FOR REVISING THE CEB METHOD

This section presents a range of potential options for revising the CEB method based on

the studies previously described.

Option 1 - Do Nothing

This is not a viable option. At a minimum, CEB needs to follow the recommendation

from the peer reviewed research report that stated our current value for skin surface area is not

current and recommended adopting the value from EPA, 1987a. 

Option 2 -Exposure Factors Handbook (EFH) skin surface area of hand, Current Q  values

This option would incorporate the recommendation of revising the skin surface area

estimate for the hand. Also, using the Q  values from the 1984 Versar report would maintain

consistency with EAB.

However, using the Q  values from the 1984 report would ignore the fact that the

experiments were redone and the data on the water-based liquids was ultimately discarded in the

1992 final report. It would also set a bad precedent by giving higher weight to a draft report than

to a final, which would undermine the credibility of the method. It also would continue the use

of the highly questionable and frequently criticized value of 14 mg/cm2 for immersion which

would also ignore one of the important findings from the 1996 research report that available data

in the literature indicate a maximum dermal retention of 4 to 10 mg/cm2 for liquids and 10

mg/cm2 for solids.

Therefore, this option is also not a viable option.

Option 3 - Option 2 Plus Q  values from EPA, 1992b

This option would incorporate the 1996 report s findings on skin surface area and

maximum dermal retention for liquids and solids from available data, and use the Q  values

from the final report of the Versar research. All 3 of these factors would significantly increase

the credibility of the CEB method. Using the EFH values for skin surface area would also make

CEB consistent with the Office of Pesticides. This is the minimum option for CEB to consider

and would result in the following table.
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3.2

Table 4: Typical Factors for Calculation of Dermal Exposure

Activity Typical Examples

S

1

(cm2)

Q

2

(mg/cm2)

Resulting Typical

Contact (mg)

Routine immersion,

2 hands

" Handling wet surfaces

" Filling/dumping containers

 of powders, flakes, granules

" Spray painting

840 1.3 - 10.3 1,100 to 8,700

Routine co ntact, 

2 hands

" Maintenance/manual

 cleaning of equipment

" Unloading filter cake

" Changing filter

" Filling drum w ith liquid

840 0.7 - 2.1 590 to 1,800

Routine co ntact, 

1 hand

420 0.7 - 2.1 290 to 880

Incidental co ntact, 2

hands

" Connecting transfer line

" Weighing powder/

 scooping /mixing (i.e., dye

 weighing)

840 0.7 - 2.1 590 to 1,800

Incidental co ntact, 1

hand

" Sampling

" Ladling liquid /bench sca le

 liquid transfer

420 0.7 - 2.1 290 to 880

Notes:

1 - Values taken from EPA Exposure Factors Handbook, 1997

2 - Values taken from Versar, 1992

Option 4 - Option 3 plus Q  values from PHED database (as reported in SAIC, 1996).

The SAIC research report investigated the PHED database to find dermal monitoring data

that could be compared to the CEB method. Data on open mixing of aqueous suspensions or

solutions was judged to be comparable to activities addressed by the CEB method such as filling

of drums with liquid and ladling liquid/bench scale liquid transfer. The PHED Q  values

expressed as 90th percentile estimated exposure with 4 hrs of exposure using time normalized

data ranged from 0.5 - 1.8 mg/cm2.
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3.3

This option incorporates these data into the CEB dermal assessment table. The only net

changes from option 3 are to change the Q  value range from 0.7 - 2.1 to 0.5 - 2.1 and to report

that the basis for this range is both Versar, 1992 and PHED. There are significant advantages to

doing this in terms of the credibility of the CEB method. One, it now expands the basis of the

CEB Q  values from laboratory simulation to include actual field monitoring data (albeit for

pesticides). It also addresses a regularly voiced criticism of the current CEB method that it

doesn t utilize data available from another EPA program office. The dermal table for this option

is as follows.

Table 5: Typical Factors for Calculation of Dermal Exposure

Activity Typical Examples

S

1

(cm2)

Q

(mg/cm2)

Resulting Typical

Contact (mg)

Routine immersion,

2 hands

" Handling wet surfaces

" Filling/dumping containers

 of powders, flakes, granules

" Spray painting

840 1.3 - 10.3 21,100 to 8,700

Routine co ntact, 

2 hands

" Maintenance/manual

 cleaning of equipment

" Unloading filter cake

" Changing filter

" Filling drum w ith liquid

840 0.5 - 2.12,3 420 to 1,800

Routine co ntact, 

1 hand

420 0.5 - 2.12,3 210 to 880

Incidental co ntact, 2

hands

" Connecting transfer line

" Weighing powder/

 scooping /mixing (i.e., dye

 weighing)

840 0.5 - 2.12,3 420 to 1,800

Incidental co ntact, 1

hand

" Sampling

" Ladling liquid /bench sca le

 liquid transfer

420 0.5 - 2.12,3 210 to 880

Notes:

1 - Values taken from EPA Exposure Factors Handbook, 1997

2 - Values taken from Versar, 1992

3 - PHED (as reported in SAIC, 1996)
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3.4

Option 5 - Option 4 (for liquids) Plus Separate Table for Solids ( Q  or mg/day exposure taken

from PHED (as reported in SAIC, 1996), USEPA, 1992 and Lansink, et.al., 1996).

The current CEB method and the tables in the previous options all use data on dermal

exposure to liquids as a basis for making estimates for solids. At the time the CEB method was

developed, data on dermal exposure to solids was unavailable so the Versar liquid data was the

best data available. However, data on solids is now available (as described in Section 2 and

presented in the Appendix). This option utilizes the solids data as a more appropriate basis for

estimating dermal exposure to powders in keeping with CEB s exposure assessment hierarchy as

summarized below.

CEB s Exposure Assessment Hierarchy (in decreasing order of preference)

1. Monitoring data for the substance of concern

2. Data on analogous substances

3. Generic scenarios

4. Regulatory standards

5. Models

In this option, assessment factors for activities involving solids are derived from the

available data on solids exposure from the PHED database, EPA, 1992 and Lansink, 1996. This

data is summarized below.

# Worker Activity Data Summary

1 Filter cake removal 0.05 - 0.79 mg/cm2

(0.30 mg/cm2 - avg)

USEPA, 1992

2 Loading of tray dryer 0.01 to 0.083 mg/cm2

(0.046 mg/cm2 - avg)

USEPA, 1992

3 Tray Unloading 0.006 to 0.088 mg/cm2

(0.039 mg/cm2 - avg)

USEPA, 1992

4 Open mixing of wettable

powder

0.79 mg/cm2 (mean)

1.7 mg/cm2 (90%)

PHED (as reported in

SAIC, 1996)

5 Collection of raw material 139 to 1090 mg

476 mg(mean)

1064 mg (90%)

Lansink, 1996

6 Manual Weighing 247 to 2511 mg

685 mg(mean)

Lansink, 1996
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# Worker Activity Data Summary

3.5

7 Manual Dumping 123 to 4214 mg

888 mg (mean)

3046 mg(90%)

Lansink, 1996

8 Collection and removal of

empty bags 

53 to 1042 mg

215 mg (mean)

1039 mg (90%)

Lansink, 1996

In deciding what values to use for a dermal assessment factors table, it was useful to

consider the purpose of the table. The dermal assessment factor table is intended for use in

screening-level assessments, therefore values that would result in a conservative, screening-level

estimate were chosen. For each activity, this consisted of the 90% values where available or the

high-end of the range if the 90% value was not given. This selection of conservative values

could be further emphasized by changing the name of the table to Factors for Screening-Level

Assessments of Dermal Exposures .

The dermal exposure assessment factor tables for liquids and solids for this option are

provided below.
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3.6

Table 6a: Factors for Screening-Level Assessments of Dermal Exposure - Liquids

Activity Typical Examples

S

1

(cm2)

Q

(mg/cm2)

Resulting Typical

Contact (mg)

Routine immersion,

2 hands

" Handling wet surfaces

" Spray painting

840 1.3 - 10.3 21,100 to 8,700

Routine co ntact, 

2 hands

" Maintenance/manual

 cleaning of equipment

" Filling drum w ith liquid

840 0.5 - 2.12,3 420 to 1,800

Routine co ntact, 

1 hand

420 0.5 - 2.12,3 210 to 880

Incidental co ntact, 2

hands

" Connecting transfer line 840 0.5 - 2.12,3 420 to 1,800

Incidental co ntact, 1

hand

" Sampling

" Ladling liquid /bench sca le

 liquid transfer

420 0.5 - 2.12,3 210 to 880

Notes:

1 - Values taken from EPA Exposure Factors Handbook, 1997

2 - Values taken from Versar, 1992

3 - PHED (as reported in SAIC, 1996)
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3.7

Table 6b: Factors for Screening-Level Assessments of Dermal Exposure - solids

Activity Typical Examples

S

1

(cm2)

Q

(mg/cm2)

Resulting Dermal

Contact (mg)

Routine co ntact, 2

hands

" Filling/dumping containers

 of powders, flakes, granules

1400-30002

Routine co ntact, 

2 hands

" Unloading filter cake

" Changing filter

" Handling bags of raw materials

(full or empty)

840 0.83

660

11004

Incidental co ntact, 2

hands

" Weighing powder/

 scooping /mixing (i.e., dye

 weighing)

" Loading, unloading tray dryer 840 0.13

1400 - 25002

100

Notes:

1 - Values taken from EPA Exposure Factors Handbook, 1997

2 - Low-end of range from PHED (as reported in SAIC, 1996) 90th percentile estimate of 1.7 mg/cm2 for open

mixing of wettable powders and 840 cm2 surface area. High-end of range from Lansink, 1996

3 - Values taken from USEPA, 1992 

4 - Lansink, 1996

The activity, Handling bags of raw materials (full or empty) was not previously part of

CEB s dermal assessment factors table. The issue of the appropriate selection of terms such as

 routine  and incidental  to characterize the frequency of contact is not part of the scope of this

paper. This activity has been included in the routine  contact category because that would be

more conservative from EPA s standpoint for risk screening purposes. On another note, the

activity of filling/dumping of powder, flakes, and granules  is no longer categorized as routine

immersion  since the immersion data for liquids from the EPA, 1992 report is no longer used as

a basis for estimate.
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3.8

Option 6 - Option 5 Plus Use of Data on Liquids from PMN Study

One study that has not yet been utilized in developing the above options is the study

performed by a PMN submitter (Anonymous, 1996). This study did yield some useful data and

this option discusses the possibility of incorporating this data into the table of factors for

screening-level assessments of dermal exposure to liquids.

The data from the study is summarized below.

Table 7: Data from PMN Study

Activity Data (Exposure to the hands)

(mg)

Process Operators 2.42; 0.016; 0.0069; 0.0027; 0.0025; 0.512

Maintenance mechanics 0.008; 0.005; 0.00086; 505.21

; 310.11

Note: 

1- this activity included repair of a leaky pump

In considering whether to add case-specific monitoring data to a table of factors for

screening-level assessments, the key question to ask is: Is there enough information in the study

to make a case that the result could be considered representative of a reasonable worst-case

exposure?  If so, then the data from the study could be considered for incorporation into the

table.

For the case of process operators, no such case can be made. Although the study does

provide descriptions of the duties, there is not enough information to conclude that the results

obtained on the day of monitoring include a high-end result. The data may in fact be at the

lower-end of the potential exposure range. Further monitoring would need to be done to get a

better understanding of the exposure potential for this activity. Therefore, the data for this

activity, although useful for the PMN specific assessment it was developed for, and useful in

general by CEB for more refined estimates of dermal exposure, is not appropriate for inclusion in

a table of factors for screening-level assessments.

The data on the maintenance mechanics is a different story. It does seem to include a

condition that could be considered reasonable worst-case (repair of pump leaks). This is

evidenced by the fact that the exposure for these workers is more than 4 orders of magnitude

greater than the exposure for workers who did not repair leaking pumps. 

In considering whether to incorporate this data, it is useful to refer to the Option 5 table

for liquids which presents a range of 420 to 1800 mg for maintenance. The result from the PMN
Options for Revising CEB Dermal Method - Final 06/00

3.9

study already falls within this range so one option is to keep the factors as they are and note that

it is further supported by data from a field study. The alternative would be to present a specific

estimate for maintenance - pump repair. Although attractive, it is argued here that this is less

preferable because it sets a precedent for over complicating the table by presenting very casespecific factors (Do we also include maintenance - distillation column repair, maintenance - dryer

repair, etc.?) It can also be argued that this would also be less credible since more data would

need to be gathered to say with confidence that the high-end estimate of exposure for pump

repair is only up to 505 mg and for general maintenance it is up to 1800 mg. 

Therefore, the only net change caused by including the results from the PMN study is to

expand the basis for the estimate for maintenance/manual cleaning of equipment in the Option 5

liquids table. Table 1a from Option 5 would now look as follows.

Table 8a: Factors for Screening-Level Assessments of Dermal Exposure - Liquids

Activity Typical Examples

S

1

(cm2)

Q

(mg/cm2)

Resulting Dermal

Contact (mg)

Routine immersion,

2 hands

" Handling wet surfaces

" Spray painting

840 1.3 - 10.3 21,100 to 8,700

Routine co ntact, 

2 hands

" Maintenance/manual

 cleaning of equipment

840 0.5 - 2.12,3 420 to 1,8002,3,4

Routine co ntact, 

2 hands

" Filling drum w ith liquid 840 0.5 - 2.12,3 420 to 1,800

Incidental co ntact, 2

hands

" Connecting transfer line 840 0.5 - 2.12,3 420 to 1,800

Incidental co ntact, 1

hand

" Sampling

" Ladling liquid /bench sca le

 liquid transfer

420 0.5 - 2.12,3 210 to 880

Notes:

1 - Values taken from EPA Exposure Factors Handbook, 1997

2 - Values taken from Versar, 1992

3 - PHED (as reported in SAIC, 1996)

4 - Anonymous, 1996
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Option 7 - Option 6 Plus Grouping Data from Similar Solids Activities

This option explores the possibility of grouping data from similar solids activities to

simplify the solids table.

Previous options separated the results from the pilot plant filtration study into separate

estimates for unloading filter cake/changing the filter and loading/unloading tray dryer. The

problem in doing that is that the data set is limited (only 1 pilot-scale study), and gives a result of

100 mg for loading/unloading tray dryer that is significantly lower than for the other activities. 

Inferring that exposure for this activity is significantly lower than for other solid handling

activities is hard to defend given the limited data it is based on. It also goes against the intent of

these tables to present conservative estimates for screening purposes.

A more preferred approach would be to view the activities of filter unloading and tray

dryer loading/unloading more generally and classify the activity as, Handling wet or dried

material in a filtration and drying process . The high-end result measured for unloading filter

cake could still be used as the screening-level assessment factor for this more generally described

activity. 

Previous options also had separate assessments for the activities of filling/dumping

containers of powder, flakes, granules , and for weighing powder/scooping/mixing . The SAIC

research report recommended applying the same PHED data to both activities. The data from the

Lansink, 1996 study showed small differences in the resulting exposure from these activities. 

Clustering these two activity descriptions into one group would be consistent with these two

reports and have the added advantage of simplifying the solids table. 

The liquids table for this option would be the same as for option 6. The solids table

incorporating these changes would look as follows.
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3.11

Table 8b: Factors for Screening-Level Assessments of Dermal Exposure - solids

Activity Typical Examples

S

1

(cm2)

Q

(mg/cm2)

Resulting

Dermal

Contact (mg)

Routine co ntact, 2

hands

" Filling/dumping containers

 of powders, flakes, granules

" Weighing powder/

 scooping /mixing (i.e., dye

 weighing)

1400 - 30002

Routine co ntact, 

2 hands

" Handling wet or dried material in a

filtration and drying process 

840 0.83

660

Routine contact " Handling bags of raw materials (full or

empty)

11004

Notes:

1 - Values taken from EPA Exposure Factors Handbook, 1997

2 - Low-end of range from PHED (as reported in SAIC, 1996) 90th percentile estimate of 1.7 mg/cm2 for open

mixing of wettable powders and 840 cm2 surface area. High-end of range from Lansink, 1996

3 - Values taken from USEPA, 1992 

4 - Lansink, 1996

Option 8 - Option 7 Plus Dermal Assessment Factors for Other Parts of the Body

As previously discussed, CEB s peer reviewed dermal research report recommended that

the data from the PHED for other parts of the body should be used with the current CEB method. 

Table 8-1 from that report is reproduced below.
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3.12

Table 8-1 from SAIC, 1996: Recommended Dermal Retention Rates as Input parameters

for the CEB Dermal Exposure Estimating Method

Dermal Retention (ug/cm2)

Body Section Mixing of Aqueous

Suspension

Mixing of Solution Mixing of

Wettable Powder

with Liquid

Dry Mixing of

Granu le

Head/Face 15 15 10 20

Shoulder 10 10 110 50

Upper Arms 1 5 30

Chest 60 40 120 60

Back 10 10 100 10

Forearms 10 50 240 240

Thigh 110 30 90 160

Shin or Calf 30 30 

Ankle 10 1 

These values were taken from the estimated 90th percentile deposition from the PHED

database. The judgement given in the report was that the liquid mixing results could be applied

to CEB s activities of filling drums with liquid and ladling liquid/bench scale liquid transfer. 

The solid mixing results could be applied to the activities of filling, dumping containers of

powder, flakes, granules and weighing powder/scooping/mixing. The resulting assessment

factors for other parts of the body based on these data are presented below.
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3.13

Table 9: Factors for Screening-Level Assessments of Dermal Exposure to Other Parts of

the Body for Work Activities Involving Transfer of Liquids (Filling drums with liquid,

ladling liquid, bench-scale liquid transfer)

Body Section

S

1

(cm2

)

Q

2

(mg/cm2

)

Resulting Dermal

Contact3

 (mg)

Head/Face 1180 0.015 20

Shoulders 1319 0.010 15

Upper Arms 1430 0.001 - 0.005 1 - 10

Chest 1550 0.040 - 0.060 60 - 90

Back 1550 0.010 20

Forearms 1140 0.010 - 0.050 10 - 50

Thigh 1980 0.030 - 0.110 60 - 200

Shin or Ca lf 2070 0.030 60

Ankle 1120 0.010 10

 Notes:

1 - Values taken from EPA Exposure Factors Handb ook, 1997 except for Shoulders, Back and Chest which were

derived from Percentages in Popendorf anatomic model (CEB, 1991) and the total mean surface area for men of 1.94

m2 (EPA, 1997)

2 - Values taken from Table 8-1 in SAIC, 1996

3 - Values ro unded to nearest 10 (as in 10, 20 etc.)
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3.14

Table 10: Factors for Screening-Level Assessments of Dermal Exposure to Other Parts of

the Body for Work Activities Involving Transfer of Solids (filling, dumping containers of

powder, flakes, granules and weighing powder/scooping/mixing)

Body Section

S

1

(cm2

)

Q

2

(mg/cm2

)

Resulting Dermal

Contact3

 (mg)

Head/Face 1180 0.010 - 0.020 10 - 20

Shoulders 1319 0.050 - 0.110 70 - 150

Upper Arms 1430 0.030 40

Chest 1550 0.060 - 0.120 90 - 190

Back 1550 0.010 - 0.100 20 - 160

Forearms 1140 0.240 270

Thigh 1980 0.090 - 0.160 180 - 320

Shin or Ca lf 2070 0.030 60

Ankle 1120 0.001 1

Notes:

1 - Values taken from EPA Exposure Factors Handb ook, 1997 except for Shoulders, Back and Chest which were

derived from Percentages in Popendorf anatomic model (CEB, 1991) and the total mean surface area for men of 1.94

m2 (EPA, 1997)

2 - Values taken from Table 8-1 in SAIC, 1996

3 - Values ro unded to nearest 10 (as in 10, 20 etc.)

Option 9 - Option 8 Plus Formal Incorporation of CEB Guidance for Qualitative Assessments

into CEB Dermal Method

The CEB Manual presents guidance for qualitative assessments of dermal exposure in

cases where dermal exposure can t be quantified. This guidance has been used historically by

CEB in assessments for new and existing chemicals. In this option, the guidance would be

formally incorporated into the CEB method for Screening-Level Assessments of Dermal

Exposure.

This guidance is presented in the table below.
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3.15

Table 11: CEB Method for Screening-Level Assessments of Dermal Exposure - Qualitative

Assessments

Category Dermal Assessment

- Corrosives (pH >12, pH <2) Negligible

- Materials at temperatures >140 deg. F (60

deg. C)

Negligible

- Cast Solids (such as molded plastics)/PMN

in matrices such as extruded pellets 

Ex. Chemical is an additive for plastics. It

has been physically mixed and incorporated

into a plastic pellet but not chemically reacted

away.

Non-Quantifiable (Some surface contact may

occur if manually transferred)

Workers handling the plastic in the form of

pellets could get surface contact with the

chemical additive. 

- Dry  surface coatings (e.g., fiber spin

finishes)

Non-Quantifiable (If manual handling is

necessary and there is an indication that the

material may abrade from the surface,

quantify contact with fingers/palms as

appropriate)

- Gases/Vapors Non-Quantifiable (Some contact may occur in

the absence of protective clothing)
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SECTION 4 - RECOMMENDATION 

Based on review of the available information, the following key factors have been

identified for consideration in revising the current CEB method.

1. Revise estimate of skin surface area of the hand (Recommendation in SAIC,

1996).

2. Replace Q  values from 1984 Versar report with the EPA, 1992a report

(experiments were redone - 1992 was final report)

3. Available data indicate a maximum dermal retention of 4 to 10 mg/cm2 for

liquids and 10 mg/cm2 (Conclusion in Peer Reviewed Research report)

4. Use Q  values from PHED database. (Data from actual field monitoring and

from other EPA program office.)

5. Use data from dermal studies w solids for solids handling activities (more

appropriate basis than liquids data)

6. Use data from PMN dermal monitoring study (non-pesticide field data for a

liquid)

7. Use data from the other parts of the body with the current CEB method

(Recommendation of the Peer Reviewed Research).

8. Formally adopt historical guidance for qualitative assessments as part of official

CEB Dermal method.
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The following table illustrates which factors are included by the 9 different options.

Table 12: Key Factors Addressed in Each Option

Key Factor Option 

1

Option

2

Option

 3

Option

4

Option

5

Option

6

Option

7

Option

8

Option

9

Revise skin surface

area

x x x x x x x x

Use EPA, 1992a

 Q  values

x x x x x x x

Max. Dermal

retention for liquids

and solids of 10

mg/cm2

x x x x x x x

Use PHED Data for

liquids

x x x x x x

Use solids data x x x x x

Use data from PMN

study

x x x x

Use PHED data from

other parts of body

x x

Adopt CEB

qualitative guidance

x

The recommended option is #9 since it incorporates all of the key factors. This option

along with the remainder of this report was presented to the Chemical Engineering Branch for

review and comment. A summary of this review; including issues, comments, and responses, is

presented in Appendix B of this report. This internal review resulted in the following

modifications to the recommended option.

1. The terms routine  and incidental branch are left in the CEB method for now but it will be

noted that they reflect typical CEB judgements of the likelihood of contact for the example

activities.

2. The term activity  used in CEB Manual and options is changed to Type of Contact  and 

each type of contact will have a unique name to help CEB distinguish between the assumptions

associated with each.
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4.3

3. The highest values in ranges with term up to  will be used since this table is for screeninglevel purposes.

4. The methodology for assessing exposure to other parts of the body needs more development

and input from risk assessors so it won t be included as part of the CEB method for now. 

Incorporating these modifications resulted in the following table which along with table

for qualitative assessments (Table 11) is the recommended option for revising CEB s method for

screening-level dermal assessments.
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4.4

Table 13: Factors for Screening-Level Assessments of Dermal Exposure to the Hands

Type of Contact1 Typical Examples

S

2

(cm2)

Q

3

(mg/cm2)

Resulting Dermal

Contact (mg)

Routine, direct

handling of solids -

2 hands

" Filling/dumping containers

 of powders, flakes, granules

" Weighing powder/

 scooping /mixing (i.e., dye

 weighing)

" Handling wet or dried material

in a filtration and drying process 

up to 31004

Routine co ntact with

surfaces - 2 hands -

solids

" Handling bags of solid

materials (clo sed or empty)

up to 11004

Routine immersion,

2 hands - liquids

" Handling wet surfaces

" Spray painting

840 1.3 - 10.3 up to 8,700

Routine co ntact, 

2 hands - liquids

" Maintenance

" Manual cleaning of equipment

" Filling drum w ith liquid

840 0.7 - 2.1 up to 1,800

Incidental co ntact, 2

hands - liquids

" Connecting transfer line 840 0.7 - 2.1 up to 1,800

Incidental co ntact, 1

hand - liquids

" Sampling

" Ladling liquid /bench sca le

 liquid transfer

420 0.7 - 2.1 up to 900

Notes:

1- The term s routine  and incidental  reflect typical CE B judgements on likelih ood of co ntact for the exa mple

activities.

2 - Values of the skin surface area of the hands taken from: EPA Exposure Factors Handb ook, 1997 and are the

mean values for men

3 - Selected ranges of Q  Values for liq uid handling activities taken from: EPA , 1992. A Labora tory Meth od to

Determine the Retention of Liquids on the Surface of Hands, Exposure Evaluation Division, Office of Pollution

Prevention and Toxic, USEPA, EPA 747-R-92-003, September, 1992.

4 - Values fo r dermal co ntact for solids h andling activities were taken fro m: Lansink, 1 996. Lan sink, C.J.M ., 

M.S.C. Breelen, J. Marqu art, and J.J. va n Hemm en: Skin Ex posure to Calcium Carbonate in the Paint Ind ustry. 

Preliminar y Mod eling of Skin E xposure L evels to Po wders Based on F ield Data (T NO Report V 96.064 ). 

Rijswijk, The Netherlands: TNO Nutrition and Food Research Institute, 1996.
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REFERENCES

(Anonymous, 1996) Anonymous, Worker Dermal Exposure to Trichloroketone, data submitted 

to EPA for the Premanufacture Notification Program.

(CEB, 1991) Chemical Engineering Branch Manual for the Preparation of Engineering 

Assessments, Washington, D.C.: Office of Toxic Substances, U.S. 

Environmental Protection Agency, 1991.

(EPA, 1997) Exposure Factors Handbook - Volume 1: General Factors. USEPA, ORD,

August 1997. EPA/600/P-95/002Fa

(EPA, 1992a) A Laboratory Method to Determine the Retention of Liquids on the 

Surface of Hands, Exposure Evaluation Division, Office of Pollution 

Prevention and Toxic, USEPA, EPA 747-R-92-003, September, 1992.

(EPA, 1992b) Exposure and Release Estimations for Filter Press and Tray Dryer 

Operations Based on Pilot Plant Data, Office of Research and 

Development, Risk Reduction Engineering Laboratory, USEPA, March 

1992, EPA/600/R-92/039.

(EPA, 1992c) Guidelines for Exposure Assessment. FR Vol. 57, No. 104, May 29, 1992.

(EPA, 1987) Pesticide Assessment Guidelines, Subdivision U, Application Exposure 

Monitoring, Office of Pesticide Programs, Washington, D.C., 1987, EPA 

540/9-87/127.

(Lansink, 1996) Lansink, C.J.M., M.S.C. Breelen, J. Marquart, and J.J. van Hemmen: Skin 

Exposure to Calcium Carbonate in the Paint Industry. Preliminary 

Modeling of Skin Exposure Levels to Powders Based on Field Data (TNO 

Report V 96.064). Rijswijk, The Netherlands: TNO Nutrition and Food 

Research Institute, 1996.

(Popendorf and Popendorf, W.J., and J.T. Leffingwell, Regulatory organophosphate

Leffingwell, 1982) pesticide residues for farm worker protection, Residue Rev., 82: 125 - 201.

(SAIC, 1996) Science Applications International Corporation. Occupational Dermal 

Exposure Assessment - A Review of Methodologies and Field Data. Final

Report. Prepared for the U.S. EPA, Office of Pollution Prevention and 

Toxic, Chemical Engineering Branch. September 30, 1996.

(Versar, 1984) Versar, Inc., Exposure Assessment for Retention of Chemical Liquids on 
Options for Revising CEB Dermal Method - Final 06/00

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Hands, Washington, D.C., Exposure Evaluation Division, U.S. 

Environmental Protection Agency, Contract No. 68-01-6271
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APPENDIX

1. DATA FROM DERMAL STUDIES USED TO REVISE THE CEB

METHOD

1.1 Pesticide Handlers Exposure Database

1.2 USEPA, 1992a. A Laboratory Method to Determine the Retention of

Liquids on the Surface of the Hands

1.3 EPA Exposure Factors Handbook, 1997 (Final Report)

1.4 USEPA, 1992b. Exposure and Release Estimations for Filter Press

and Tray Dryer Operations Based on Pilot Plant Data. 

1.5 Skin Exposure to Calcium Carbonate in the Paint Industry - Lansink,

et. al., 1996.

1.6 Worker Dermal Exposure to Trichloroketone, Anonymous,1996

2. CEB Review of Recommended Option
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A-2

1.1 Pesticide Handlers Exposure Database
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A-3

PHED DATA FOR MIXING/LOADING OF SOLIDS (as reported in SAIC, 1996. 

Occupational Dermal Exposure Assessment - A Review of Methodologies and Field Data,

Prepared for CEB)

Source: Mixer-Loader from PHED Database

Description:

The PHED (Pesticide Handlers Exposure Database) is a generic database containing

measured inhalation and dermal exposure data for workers involved in the handling or

application of pesticides in the field. The database is designed to allow prediction of pesticide

exposure during mixing/loading, application, and flagging operations, based on any selected

combination of formulation types, mixing/loading procedures, application equipment,

procedures, clothing scenario or other parameters that may e relevant to exposure. It contains

exposure data generated by the EPA and pesticide registrants. In submitting the data, each

registrant is required to develop the information following EPA guidelines and use the standard

Exposure survey forms for record keeping.

The database contains 1700 records total. There are 556 records with dermal exposure

data under the mixer loader file. There are 4 types of solid formulations handled - wettable

powder, dry flowable solid, dust and granules. There are 5 types of liquid formulations handled -

emulsifiable concentrate, aqueous suspension, micro encapsulated, solution, and undiluted

liquid..

There are 3 types of mixing methods, (1) - open, (2) closed, mechanical pump; (3) closed,

gravity feed.

Results - Solids

TABLE 1: Estimated Gross Dermal Deposition Normalized by Quantity of Chemical

Handled (ug/cm2/lb) and Time (ug/cm2/hr) from PHED for Wettable Powder in Bags with

Open Mixing

Body Section Number of

Measurements

Mean

(ug/cm2/lb)

90th Percentile

(ug/cm2/lb)

Mean

(ug/cm2/hr)

90th Percentile

(ug/cm2/hr)

head 10 0.039 0.075 0.7217 2.110

neck front 0

neck back 0

shoulder 13 0.2062 0.4742 8.4135 27.16
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Body Section Number of

Measurements

Mean

(ug/cm2/lb)

90th Percentile

(ug/cm2/lb)

Mean

(ug/cm2/hr)

90th Percentile

(ug/cm2/hr)

A-5

upper arms 0

chest 16 0.1322 0.2143 8.9699 28.56

back 16 0.0666 0.1323 7.0829 25.60

forearms 18 0.9216 1.7605 15.438 59.04

thigh 16 0.3992 0.5127 8.7805 22.73

shin 4 0.0893 0.1754 3.7546 8.129

calf 0

ankle 4 0.0458 0.0850 0.0542 0.136

hands 7 18.991 53.21 197.48 419.51

TABLE 2: Estimated Gross Dermal Deposition Normalized by Quantity of Chemical

Handled (ug/cm2/lb) and Time (ug/cm2/hr) from PHED for Wettable Powder in Packets

with Open Mixing

Body Section Number of

Measurements

Mean

(ug/cm2/lb)

90th Percentile

(ug/cm2/lb)

Mean

(ug/cm2/hr)

90th Percentile

(ug/cm2/hr)

head 15 0.0027 0.0098 0.0996 0.4865

neck front 3 0.0009 0.0014 0.0360 0.0638

neck back 6 0.0004 0.0006 0.0142 0.0295

shoulder 6 0.0013 0.0020 0.0102 0.0150

upper arms 0

chest 15 0.0028 0.0098 0.1044 0.4865

back 15 0.0026 0.0098 0.0953 0.4865

forearms 15 0.0072 0.0098 0.2384 0.5358

thigh 15 0.0218 0.0808 0.7704 2.928

shin 3 0.0004 0.0005 0.0162 0.0258

calf 6 0.0032 0.0066 0.0300 0.0703

ankle 3 0.0011 0.0023 0.0407 0.0938

hands 5 0.0265 0.0557 0.0954 2.185

PHED DATA FOR MIXING/LOADING OF LIQUIDS
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A-6

 Results - Liquids

TABLE 3: Estimated Gross Dermal Deposition Normalized by Quantity of Chemical

Handled (ug/cm2/gal) and Time (ug/cm2/hr) from PHED for Aqueous Suspension with

Open Mixing

Body Section Number of

Measurements

Mean

(ug/cm2/gal)*

90th Percentile

(ug/cm2/gal)

Mean

(ug/cm2/hr)*

90th Percentile

(ug/cm2/hr)

head 15 0.1668/0.0100 0.0584 2.7576 3.215

neck front 0

neck back 0

shoulder 16 0.0292 0.0325 1.6373/0.4056 1.626

upper arms 6 0.0083 0.0142 0.1111 0.2118

chest 16 0.5980/0.0040 0.2919 29.166/0.7839 15.90

back 16 0.0200 0.0442 1.1407 2.600

forearms 6 0.0934 0.1776 1.1038 2.157

thigh 16 0.4971 1.1067 19.825 28.40

shin 10 5.1433 5.6337 318.58/42.53 272.06

calf 0

ankle 6 0.0809 0.1993 1.1945 2.921

hands 16 10.685 33.42 180.55 444.27

* where two numbers are presented, the first is the estimated mean and the second is the median

TABLE 4: Estimated Gross Dermal Deposition Normalized by Quantity of Chemical

Handled (ug/cm2/gal) and Time (ug/cm2/hr) from PHED for Solution with Open Mixing

Body Section Number of

Measurements

Mean

(ug/cm2/gal)*

90th Percentile

(ug/cm2/gal)

Mean

(ug/cm2/hr)*

90th Percentile

(ug/cm2/hr)

head 23 0.0267 0.0742 0.0667 3.253

neck front 0

neck back 0

shoulder 16 0.0334 0.0626 0.0699 2.095

upper arms 16 0.0067 0.0100 0.0224 1.142
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Body Section Number of

Measurements

Mean

(ug/cm2/gal)*

90th Percentile

(ug/cm2/gal)

Mean

(ug/cm2/hr)*

90th Percentile

(ug/cm2/hr)

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chest 23 0.0734 0.2519 0.6729 9.127

back 23 0.0467 0.0384 0.0656 1.496

forearms 23 0.0692 0.1351 0.7528 13.25

thigh 23 0.2769 0.2093 5.2377 7.443

shin 0

calf 7 0.0058 0.0125 0.1671 6.599

ankle 16 4.3643 14.04 1.4623 88.25

hands 6 0.1665 0.3005 3.5577 115.2

* where two numbers are presented, the first is the estimated mean and the second is the median
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1.2 USEPA, 1992a. A Laboratory Method to Determine the Retention of

Liquids on the Surface of the Hands
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Table 1: Surface Retention Rates of Selected Liquids on the Hands Under Various 

Experimental Conditions

Mineral Oil

(mg/cm2)

Cooking Oil

(mg/cm2)

Bath Oil

(mg/cm2)

Initial wipe

Initial film thickness of liquids on hands 1.36 2.07 1.49

Film thickness after partial wipe 0.54 0.75 0.51

Film thickness after full wipe 0.24 0.32 0.17

Secondary wipe

Initial film thickness of liquids on hands 1.22 1.72 1.34

Film thickness after partial wipe 0.41 0.48 0.41

Film thickness after full wipe 0.05 0.06 0.07

Immersion

Estimated film thickness of liquid on hand 10.33 6.02 5.94

Estimated film thickness of liquid

remaining after partial wipe

 1.75 1.33 1.34

Handling a rag

Initial film thickness of liquid on palms 1.43 1.38 1.76

Film thickness after partial wipe 0.38 0.31 0.46

Film thickness after partial wipe 0.11 0.01 0.18

Spill Cleanup

Estimated Initial film thickness of liquid

on hand

 1.07 0.67 0.77

Estimated film thickness of liquid

remaining after partial wipe

 0.48 0.47 0.41
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1.3 EPA Exposure Factors Handbook, 1997 (Final Report)
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Table 1: Estimates of Skin Surface Area

 Men Women

Body Part N Mean Min - Max N Mean Min - Max

Head 32 1180 900 - 1610 57 1110 953 - 1270

Trunk (Incl. neck) 32 5690 3060 - 8930 57 5420 4370 - 8670

Upper Extremities 48 3190 1690 - 4290 57 2760 2150 - 3330

Arms 32 2280 1090 - 2920 13 2100 1930 - 2350

 Upper Arms 6 1430 1220 - 1560

 Forearms 6 1140 945 - 1360

Hands 32 840 596 - 1130 12 746 639 - 824

Lower Extremities 48 6360 2830 - 8680 57 6260 4920 - 8090

 Legs 32 5050 2210 - 6560 13 4880 4230 - 5850

 Thighs 32 1980 1280 - 4030 13 2580 2580 - 3600

 Lower Legs 32 2070 930 - 2960 13 1940 1650 - 2290

Feet 32 1120 611 - 1560 13 975 834 - 1150

TOTAL 19,400 16600 -

22800

16900 14500 -

20900
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1.4 USEPA, 1992b. Exposure and Release Estimations for Filter Press

and Tray Dryer Operations Based on Pilot Plant Data. 
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Exposure and Release Estimations for Filter Press and Tray Dryer Operations Based on Pilot

Plant Data, USEPA, 1992b. 

A summary of this study and the measurements of dermal exposure is presented below.

Process:

Pilot plant utilizing a plate and frame filter press and a stationary tray dryer. A 10%

slurry of calcium carbonate in water to yield approximately 100 kg of dry calcium carbonate. 

Eight experiments were performed. Dermal exposure measured for the activities of filter cake

removal, tray loading and tray unloading.

Monitoring Method:

Hand and forearm rinses were performed as per EPA Pesticide Assessment Guidelines. 

Operator placed one hand inside a bag until the top of the bag extended above the elbow. 

Approximately 200 ml of milli Q water were poured over the operators forearm. With the bag

wrapped tightly around the upper arm of the operator, a field sampling technician rubbed the

water in the bag over the surface of the operators hand and forearms to wash calcium carbonate

particles from the skin. The operator jiggled is hand/forearm to shake water droplets off the skin

surface into the bag. The water was then poured from the bag into a glass sample jar. The rinse

procedure was repeated a second time on the same hand/forearm of the operator. After the one

hand/forearm had been rinsed two times, the other hand/forearm was washed using the separate

rinse solution. The rinse water for the right and left hand/forearm rinses were combined into a

single sample container.

Data Available:

Raw experimental data include the sample volume (in liters) of the dermal sample

obtained from the rinsing of both hands and forearms of the operator and the calcium

concentration in the sample (mg/L). The calcium was converted to CaCO3 by multiplying by a

conversion factor of 2.497. Therefore mg of exposure to CaCO3 was obtained as follows:

Sample volume (L) x Calcium concentration in sample (mg/L) x 2.497 = mg CaCO3

Dermal exposure in mg/cm2 was obtained by dividing the above result in mg by 1980

cm2 (surface area of hands and forearms as per Exposure Factors handbook)

Data is also available on the duration of the worker activity and the amount of material

processed.
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Results

1. Activity: filter cake removal

Description:

Plate and frame filter press. Worker used a spatula to scrape wet filter cake from the

filter cloth and the plate and frames of the filter press into the collection bin. Dermal exposure

occurred to both the hands and the forearms. Hands were observed to come into contact with the

filter cake throughout the operation. Forearms would rub against the filter cloths, plates and

frames.

Workers processed 60.5 to 72.9 kg, dry weight basis, in a plate and frame filter press

obtained from a chemical manufacturing plant

Table 1: Dermal Exposure for Filter Cake Removal

Experimen t # Exposure Duration (min) Dermal Ex posure to

hands and forearms

(mg) 

Dermal Exposure

(mg/cm2)

1 111 101 0.051

2 54 520 0.26

3 73 221 0.112

4 72 1560 0.79

Average 601 0.30

2. Activity: Loading of Tray Dryer

Description: Operators used a shovel to transfer wet cake from the collection bin onto the dryer

tray. The blade of the shovel was used to level the calcium carbonate on the dryer tray. Hands

were observed to come into contact with the calcium carbonate as the operator reached into the

collection bin with the shovel and as he carried the trays into the dryer. A spatula was also used

to break up the filter cake and to maneuver the filter cake around the tray surface.

This activity involved loading 75.5 to 122.5 kg of product (100%) into a tray dryer.
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Table 2: Dermal Exposure for Loading of Tray Dryer 

Experimen t # Exposure Duration (min) Dermal Ex posure to

hands and forearms

(mg)

Dermal Exposure

(mg/cm2)

1 17 19.8 0.01

2 16 25.5 0.013

3 33 164 0.083

4 10 62 0.031

5 9 143 0.072

6 14 70.2 0.035

7 25 143 0.072

8 12 93.6 0.047

Average 90.1 0.046

3. Activity: Tray Unloading

Description: Dryer was at 120 deg. C. Trays were hot and workers wore gloves in removing the

trays from the dryer. Worker would tile the tray into the collection bin allowing the calcium

carbonate to slide into the collection bin. This would cause a dust cloud to be generated. A

spatula was used to scrape the residual from the tray into the bin. Operators further banged the

tray against the side of the collection bin and then banged the spatula against the tray to get as

much of the product into the bin as possible. Dermal exposure during this operation was due to

fine solids falling into the workers gloves.

This activity involved unloading 75.5 to 122.5 kg of product (100%) from a tray dryer

Table 3: Dermal Exposure for Tray Unloading

Experimen t # Exposure Duration (min) Dermal Ex posure to

hands and forearms

(mg)

Dermal Exposure

(mg/cm2)

1 17 12.5 0.006
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Experimen t # Exposure Duration (min) Dermal Ex posure to

hands and forearms

(mg)

Dermal Exposure

(mg/cm2)

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2 9 166.4 0.084

3 6 13.8 0.007

4 6 83.2 0.042

5 7 174.2 0.088

6 5 93.6 0.047

7 7 39 0.020

8 5 28.6 0.014

Average 76.4 0.039
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1.5 Skin Exposure to Calcium Carbonate in the Paint Industry - Lansink,

et. al., 1996.
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Skin Exposure to Calcium Carbonate in the Paint Industry - Lansink, et. al., 1996.

This was a dermal monitoring study conducted during the manufacture of powdered

paint. Exposures were monitored for workers involved in weighing, dumping and handling of

bags. Details and results are presented in Appendix 1.5.

A summary of this study on dermal exposure is provided below.

Process:

Manufacture of powdered paint. The chosen substance for monitoring is calcium

carbonate. Measurements were taken in ten different paint factories. The goal was to sample 2

workers per site for a total of 20 samples.

Monitoring Method

Monitored with 100% cotton gloves to cover the forearm. Workers wore the cotton

gloves until the activity finished or up to 30 minutes. After the activity (e.g. collection and

removal of empty bags) was finished, gloves were carefully removed from the hands of the

workers by the investigator, stored by placing in a polyethylene 1-liter bottle. Samples were

extracted with 1.2N HCL and analyzed with atomic absorption spectrometry (AAS) flame

technique.

During the different activities the workers wore the cotton gloves until the activity was

finished. When the activity took longer than 30 minutes, new sampling gloves were supplied. 

Data Available

For each activity:

- number of samples

- exposure duration

- quantities handled (# of bags, mass of material)

- Min, Max, 10%, 90%, geometric mean exposures

- In addition, regression analyses were performed to examine the affect of exposure

duration, number of bags handled and amount of calcium carbonate handled on exposure. 

Results and conclusions from these analyses are presented.
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Results

a. Overall Summary Data 

Table 1: Mg of calcium carbonate

. 

# Activity No. of

Samples

Range

 (mg)

10% 

(mg)

90%

(mg)

Geometric

Mean

(mg)

1 Collection of Raw

Material

12 139 to 1090 243 1064 476

2 Manual Weighing 6 247 to 2511 685

3 Manual Dumping 19 123 to 4214 216 3046 888

4 Collection and removal

of empty bags

14 53 to 1042 55 1039 215

Table 2: Mg of calcium carbonate/hour of exposure

. 

# Activity No. of

Samples

Range

 (mg)

10% 

(mg)

90%

(mg)

Geometric

Mean

(mg)

1 Collection of Raw

Material

12 N.a. N.a. N.a. N.a.

3 Manual Dumping 19 2893 -

32709

4317 26419 10829

4 Collection and removal

of empty bags

14 N.a. N.a. N.a. N.a.

Where: N.a. = Not applicable (correlation between exposure and duration was not found)
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Table 3: Mg of calcium carbonate/bag handled

. 

# Activity No. of

Samples

Range

 (mg)

10% 

(mg)

90%

(mg)

Geometric

Mean

(mg)

1 Collection of Raw

Material

12 N.a. N.a. N.a. N.a.

3 Manual Dumping 19 39 - 527 47 217 126

4 Collection and removal

of empty bags

14 5.8 - 117 6.1. 86.6 24

Where: N.a. = Not applicable (correlation between exposure and number of bags handled was not

found)

Table 4: Mg of calcium carbonate/kg of calcium carbonate

. 

# Activity No. of

Samples

Range

 (mg)

10% 

(mg)

90%

(mg)

Geometric

Mean

(mg)

1 Collection of Raw

Material

12 N.a. N.a. N.a. N.a.

3 Manual Dumping 19 1.6 - 19.2 1.9 8.7 5.0

4 Collection and removal

of empty bags

14 N.a. N.a. N.a. N.a.

Where: N.a. = Not applicable (correlation between exposure and kg of calcium carbonate was not

found)
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b. Summaries by Worker Activity

1. Activity: Collection of raw material

Description: Manual collection of raw material (in bags), including bags of calcium carbonate, on

a pallet or (flat) car in the storehouse of raw materials and transportation of the raw material to

the place of production.

Duration lasted from 1-7 minutes

Number of bags: 2-11

Results: 13 samples

 Range: 139 to 1090 mg

 10%: 243 mg

 90%: 1064 mg

 Geometric mean: 476 mg

No correlation between frequency of contact and exposure.

2. Activity: Manual weighing

Description: Manual weighing of the amount of calcium carbonate (powder) out of bags, tons, or

cans on a balance and collecting the weighed amount in a bag or a can on a pallet. Opened bag

was put on the weigher. The calcium carbonate was scooped from the bag into another bag and

then the weighed calcium carbonate was placed on the ground or a pallet.

Event: 2-5 minutes

3-38 kg of CaCO3 handled

Results: 6 measurements

 Range: 247 to 2511 mg

 Mean: 685 mg

3. Activity: Manual Dumping

Description: Cutting bag open, lifting to dumping shelf, emptying into mixer or lifting bag to the

dumping shelf, cutting open, dumping the bag into the mixer. Higher exposures resulted when

workers swept material directly with hands into mixing vessel.

Event: 1-15 min
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2-24 bags

10 - 1000 kg of CaCO3

Results: 22 samples

 Range: 123 to 4214 mg

 Geometric mean: 888 mg

 10%: 216 mg

 90%: 3046 mg

Significant correlation found between exposure and duration, number of bags handled

and amount of calcium carbonate handled.

4. Activity: Collection and Removal of empty Bags

Description: Empty bags were brought into a barrel or to a bale press. The exposure occurred by

pushing the bags together. 

Event: 1-3 min

1-24 bags

Results: 17 samples

 Range: 53 to 1042 mg

 10%: 55 mg

 90%: 1039 mg

 Geometric mean: 215 mg

Based on regression analysis, the number of bags handled was found to have an impact on

exposure. There was no correlation of exposure with duration.
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1.6 Worker Dermal Exposure to Trichloroketone, Anonymous,1996
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Worker Dermal Exposure to Trichloroketone, Anonymous,1996

This report presents the results of a dermal monitoring study conducted by a PMN

submitter. Exposure was measured for chemical operators and workers involved in maintenance

activities. A summary is presented below.

Process:

Production of a site-limited intermediate. Dermal exposure study was conducted on one

day of the process.

Monitoring Method:

- gloves

Nitrile outer and cotton inner gloves were collected for chemical process operators and

maintenance mechanics. Each pair of nitrile and cotton gloves were worn for a maximum of 2

hours. After the two hours the gloves were removed in a clean non-production area by

unexposed personnel wearing latex gloves. The gloves were placed in a single plastic sample

bag which was then shipped to the Analytical lab. At the lab, the gloves were removed from the

bag and placed into a jar containing isopropanol. The solution was then analyzed for PMN

chemical.

- Coveralls, underwear

At the end of the workday for subject employees, both coveralls and inner full-body

underwear were carefully removed by the subject employees and handed to unexposed study

personnel wearing latex gloves. 100 cm2 patches were cut from the garments for various body

regions to correspond with body regions in the EPA Pesticide Assessment Guidelines, Applicator

Exposure Monitoring. The patches were placed in a plastic sample bag for transport to the

analytical lab. At the lab, the patches were removed and placed into a jar containing isopropanol. 

The solution was then analyzed for PMN chemical.

Activity and Exposure Duration (see attached)
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Data Available

The analytical method determined the concentration of PMN chemical in the sample (in

ng/ml). This raw data was converted to ng/cm2 by multiplying by the volume of the sample and

dividing by the area of the glove or cloth patch sampled. This converted value of ng/cm2 was

converted to ng/day (or ug/day) for various body parts by multiplying by the estimated area of the

body part. In this study, body part skin surface areas from the Pesticide Applicator Guidelines

were used for this conversion.

Data tables in the report include a summary of the PMN data (PMN found in samples of

underwear, cotton gloves coverall and nitrile gloves, ng/cm2, not corrected for recovery), PMN

lab and field recovery percentages, and the PMN daily dermal exposure totals, corrected for field

recovery. The PMN daily dermal exposure totals are presented in the tables below for operators

and maintenance personnel. 
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Table 1: TCK - Unprotected (Outside)-Exposure (ug/person/day) for Operators

Region of the body #1 #2 #3 #4 #5 #6

Head 1.3 0.28 0.28 0.28 0.28 0.28

Neck back 0.052 0.017 0.017 0.017 0.017 0.017

Neck front 0.21 0.035 0.035 0.035 0.035 0.035

Chest/

Stomach

5.04 0.76 0.76 0.76 0.76 0.76

Back 1.72 0.76 0.76 0.76 0.76 0.76

Arm/

Upper

3.48 0.62 0.62 0.62 0.62 0.62

Forearm 1.56 0.26 0.26 0.26 0.26 0.26

Thigh 10.92 0.83 0.83 0.83 1.92 3.24

Leg Lower 6.81 0.52 0.52 0.52 1.20 2.03

Feet 3.74 0.28 0.28 0.28 0.66 1.11

Subtotal 34.84 ug

(0.035 mg)

4.37 ug

(0.004 mg)

4.37 ug

(0.004 mg)

4.37 ug

(0.004 mg)

6.52 ug

(0.006 mg)

9.12 ug

(0.009 mg)

Hand 2421.7 16.39 6.92 2.75 2.5 512.04

Total 2456.51 ug

(2.46 mg)

20.75 ug

(0.021 mg)

11.29 ug

(0.011 mg)

7.12 ug

(0.007 mg)

9.02 ug

(0.009 mg)

521.16 ug

(0.52 mg)

Notes:

#1 = A  Operator

#2 = B  Operator

#3 = D  Operator

#4 = E  Operator

#5 = Relief Operator #1

#6 = Relief Operator #2
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Table 2: TCK - Unprotected (Outside)-Exposure (ug/person/day) for Maintenance Personnel

Region of the body #1 #2 #3 #4 #5

Head 0.39 0.27 0.59 9.93 2.63

Neck back 0.017 0.017 0.017 0.86 0.12

Neck front 0.068 0.034 0.10 1.42 0.41

Chest/

Stomach

1.68 0.75 3.31 33.6 9.69

Back 0.75 0.75 0.75 28.1 3.68

Arm/

Upper

0.61 0.61 0.61 20.97 10.39

Forearm 0.25 0.25 0.25 10.66 5.85

Thigh 1.92 1.92 0.81 82.1 884.2

Leg Lower 1.19 1.19 0.51 51.15 550.88

Feet 0.66 0.66 0.27 28.15 303.2

Subtotal 7.53 ug 

(0.007 mg)

6.44 ug 

(0.006 mg)

7.25 ug 

(0.007 mg)

267 ug 

(0.27 mg)

1771.07 ug

(1.77 mg)

Hand 8.29 5.14 0.86 505157.21 310147.84

Total 15.82 ug

 (0.016 mg)

11.58 ug 

(0.012 mg)

8.12 ug 

(0.008 mg)

505424.21 ug

505.42 mg

311918.91 ug

(311.92 mg)

Notes:

#1 = Maintenance mechanic, instr/electrical #1

#2 = Maintenance mechanic, mechanical; #1

#3 = Maintenance mechanic, instr/electrical #2

#4 = Maintenance mechanic, mechanical #2

#5 = Maintenance mechanic, mechanical #3
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2 CEB Review of Recommended Option
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CEB Review of Recommended Option - April and May, 2000 - Issues,

Comments, Responses

1. Issue: Use of routine  and incidental  terms 

Comment(1): Strike routine  and incidental  terms from the table for now until we choose to

address these judgements more fully.

Comment (2): Leave in routine/incidental terms for now because of YX exposure-based policy.

Response: Agree with the concern. The problem is the YX policy which has routine  contacts

as part of the policy. For now the current designations will be kept and where there are additions

to the table, they will be conservatively regarded as routine . 

2. Comment: Change activity  used in CEB Manual and options to something else like

 Model  or descriptor .

Response: Agree. Activity  is not the best term. I prefer Type of Contact .

3. Comment: Each type of contact (or Model , Descriptor ) must have a unique name to

help CEB distinguish between the assumptions associated with each.

Response: Agree

4. Issue: Dermal exposure to other parts of the body

Comment (1): Needs more development work, recommend dropping from option we adopt.

Comment (2): Least defensible but keep because it may find use in some situations

Comment (3): Leave in the detailed report but don t adopt now as part of the method pending

further development

Response: Was a recommendation from the Peer Reviewed Report. I would like to keep it so we

don t lose  those results but agree that it should be clearly distinguished from the hands in

implementation memo. 
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5. Issue: Use of Ranges in table

Comment (1): Use highest values in ranges only with term up to . Reasons: prevents exclusion

of other relevant data; prevents false impression of accuracy we can give by reporting a range; for

screening, risk assessors will only use the highest value anyway.

Comment (2): Ranges are OK but guidance to contractors/CEB is to report one number for

assessment purposes

Response: Agree that contractors should only provide one number. That is actually current

policy and during the implementation of the revised method we can reemphasize that to ERG and

CEB staff. If there is a need for a more refined assessment, CEB assessor can review the studies

in more detail to determine a more appropriate estimate for their situation. However, to ensure

consistency, these more refined assessments should be reviewed and saved in a Dermal 

subdirectory on the K:\Group\CEB directory.

I left in the range for the liquid values to maintain consistency with the current method. 

6. Comment: Exposure Descriptors need to be included. Suggested language - Values are

highest in range and are high-end estimates. For use in assessments, these values are what-if 

estimates and may be reported as high-end values in studies from which the values are taken. 

Response: Agree that exposure descriptors need to be included. The available data give support 

that the upper end values in the table are high-end exposures. The Implementation Memo will

address descriptors and the basis for the high-end call. 

7. Issue: Constructing the ranges with data from different studies. Example: using the

PHED 90% value and Paint study 90% value together: 

Suggestions:

- Use of liquid field data from PHED, PMN study - use primarily to determine the

reasonableness of our method (e.g for validation purposes).

- Use of pilot plant filtration and PHED solids - use primarily to determine the

reasonableness of our method (e.g. for validation for data from the paint study)

Response: Reoriented approach to using the EPA, 1992 lab study as the base method for liquids

and the paint study as the base method for solids. All the field data for liquids (PHED, PMN,

other literature data cited in SAIC, 1996 fall within the Versar range (even the high-end values)

and can be used as validation. The remaining solids data from PHED, the pilot plant filtration

study and other literature data cited in SAIC, 1996 also fall within the paint study range and can
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be used for validation. 

8. Comment: Recommend adopting the qualitative guidance in the option we adopt.

9. Comments: ..we can develop and adopt an interim option...., perhaps immediately 

 ...get this thing on line 

Response: Amen

10. Comment: Recommend Peer Review

Response: Definitely. The next steps are to draft an Implementation memo to implement the

method, finalize the background report and then to pursue a Peer Review