X-/EPA
Atmospheric Research and Exposure
Assessment Laboratory
Research Triangle Park, NC 27711
Office of
Toxic Substances
Washington, DC 20460
Final Draft
September 1991
Research and Development & Pesticides and Toxic Substances
A Report on the
Lead Reference Materials
Workshop
Washington, DC
May 13-14,1991
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Final Draft
September 1991
A Report on the
Lead Reference Materials Workshop
Washington, DC
May 13-14,1991
Prepared by
E. E. Williams
P. M. Grohse
J. D. Neefus
W. F. Gutknecht
Center for Environmental Measurements and Quality Assurance
Research Triangle Institute
Research Triangle Park, North Carolina 27709-2194
EPA Contract No. 68D10009
RTI Project No. 4960-024
Dr. Ben Lim, Work Assignment Manager
Dr. Joseph J. Breen, Project Officer
Field Studies Branch
Exposure Evaluation Division
Office of Toxic Substances
Office of Pesticides and Toxic Substances
U.S. Environmental Protection Agency
Washington, DC 20560
Ms. Sharon Harper, Co-Work Assignment Manager
Mr. Darryl von Lehmden, Co-Project Officer
Atmospheric Research and Exposure Assessment Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
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EXECUTIVE SUMMARY
The potential impact on health from environmental lead has resulted in increased interest
in lead exposure by Federal, State and local governmental agencies. As a result, programs
committed to sampling and analysis of lead are increasing nationwide. The development of
reference materials that are appropriate to the media of interest is essential to the success of these
programs. Therefore the USEPA sponsored a Lead Reference Materials Workshop that was held
on May 13-14,1991 at EPA Headquarters in Washington, DC. The purpose of the workshop
was to review the status of analytical methods typically used for lead analysis and to determine,
as specifically as possible, the types and characteristics of reference materials that would be most
appropriate to environmental lead analyses.
The workshop was attended by 33 persons with experience in lead measurement
methodologies. The morning session of the workshop began with a brief overview of the
purpose and goals for the meetings and was followed by presentations on the following topics:
need for reference materials,
health-based performance criteria, regulations and other driving forces,
portable and laboratory X-ray fluorescence,
atomic absorption spectrometry/plasma emission spectrometry,
field test kits, and
blood analysis.
In the afternoon, the attendees divided into three subgroups (atomic absorption
spectrometry/plasma emissions spectrometry, X-ray fluorescence and field test kits) to discuss
these specific methodologies and the reference materials needed for each. At the end of the first
day, all attendees reconvened to assess subgroup progress. The next day subgroup discussions
continued through the morning, and all attendees met together again on the afternoon of May 14
to present conclusions and recommendations. As a result of this effort, parameters for reference
materials in paint, soil, and dust were proposed.
Parameters specified for each medium include composition, concentration levels and
acceptable error, rationale for selection of levels, analytical aliquot size, and an estimated
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quantity needed for 2000-3000 laboratories. Composition was generally specified as "real-
world", and concentration levels were selected to reflect health effects or regulatory levels. An
error margin of + 10 percent was established for all performance evaluation standards, except for
low level soil and dust samples (+. 20%) and dust wipes (+. 25%). Aliquot sizes of 0.1 mL for
blood, 100-250 mg for paint, soil and dust (atomic absorption spectrometry and plasma emission
spectrometry), and 1-2 gm for soil and dust for X-ray fluorescence were considered appropriate.
Total estimated quantities of 150 liters of blood, and 20-250 kilograms each of paint, soil and
dust for each concentration level were recommended.
Because specific recommendations for performance evaluation standards were made on
the basis of input from experts intimately familiar with sampling and analysis of lead, the Lead
Reference Materials Workshop was successful and the resulting recommendations may be used
with confidence.
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ACKNOWLEDGEMENTS
This document was prepared under the direction of Dr. Ben S. Lira, Exposure Evaluation
Division, Office of Toxic Substances, U.S. Environmental Protection Agency, Washington, D.C.
(EED/OTS), and Ms. Sharon L. Harper, Atmospheric Research and Exposure Assessment
Laboratory (AREAL), U.S. Environmental Protection Agency, Research Triangle Park, NC.
Special acknowledgement is given to Dr. Randall J. Cramer and Dr. Joseph Breen
(EED/OTS/EPA) and Mr. Michael E. Beard and Mr. Darryl J. von Lehmden (AREAL/EPA), for
their careful review.
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DISCLAIMER
The information in this document has been funded wholly or in part by the United States
Environmental Protection Agency under EPA Contract No. 68D10009 to the Research Triangle
Institute. It has been subjected to the Agency's peer and administrative review, and it has been
approved for publication as an EPA document. Mention of trade names or commercial products
does not constitute endorsement or recommendation for use.
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TABLE OF CONTENTS
EXECUTIVE SUMMARY
ACKNOWLEDGMENTS
DISCLAIMER
1.0 Introduction 1-1
1.1 Goals of Workshop 1-1
1.2 Structure of Workshop 1-1
2.0 Summary of Presentations 2-1
3.0 AAS/ICP 3-1
3.1 Introduction 3-1
3.2 Blood 3-1
3.3 Paint 3-2
3.4 Dust - Bulk (vacuumed) 3-5
3.5 Dust Wipes 3-5
3.6 Soils 3-6
4.0 Test Kits 4-1
4.1 Introduction 4-1
4.2 Paint 4-1
4.3 Dust 4-2
4.4 Soil 4-2
5.0 X-Ray Fluorescence 5-1
5.1 Introduction 5-1
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TABLE OF CONTENTS (CONT'D)
5.2 Paint Films 5-1
5.3 Soils 5-2
5.4 Dust 5-2
6.0 References 6-1
List of Appendixes
APPENDIX A - List of "Principal Concerns for the Lead Reference Materials Workshop" sent
to Potential Attendees
APPENDIX B- List of Attendees
List of Tables
Table 2-1 Concentrations of Concern for Lead in Environmental Media 2-4
Table 3-1 Proposed Lead Reference Standards for AAS/ICP 3-3
Table 4-1 Proposed Lead Reference Standards for Test Kits 4-3
Table 5-1 Proposed Lead Reference Standards for XRF Analysis 5-3
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Section 1
Introduction
1.1 Goals of Workshop
Programs supporting studies of the toxicity and bioavailability of lead, environmental
monitoring of lead, and abatement and clearance of lead in housing are being initiated at ever-
increasing rates. Examples include the Housing and Urban Development (HUD) National Survey,
the EPA Three City Study, method evaluation studies sponsored by EPA, and abatement programs
carried out in Maryland, Massachusetts, and in other states. The analytical methods being used in
this work include portable and laboratory X-ray fluorescence (XRF), plasma emission spectrometry
(ICP), atomic absorption spectrometry (AAS), and field test kits. In most of this work, the accuracy
of the analyses is uncertain because appropriate reference materials (RMs) are not available. As a
result, there are questions about the comparability of studies, an essential factor in evaluating the
extent of lead contamination.
To deal with this important issue, the U. S. Environmental Protection Agency sponsored a
Lead Reference Materials Workshop to review the availability of, and the requirements for,
reference materials for lead in environmental media. The goal of the workshop was to delineate
criteria for the preparation of reference materials appropriate to the following:
sample composition - "real-world" materials
concentration ranges pertinent to
- health effects
- regulations
- typicality of "real-world" sampling
- instrumental limitations
chemical and physical (e.g., particle shapes and sizes) forms
amounts of material necessary to serve lead programs nationwide, such as potential
laboratory accreditation or proficiency testing programs for lead.
1.2 Structure of Workshop
Following planning efforts by EPA, National Institute for Standards and Technology (NIST)
and EPA-contractor staff, letters of invitation were mailed to 49 representatives from Federal and
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State governmental agencies and a number of EPA contractors with experience in sampling and
analytical methodologies applicable to lead-based paint exposure studies. The intent was to invite
representatives intimately familiar with measurement methodologies in environmental media (paint,
soil, and dust), and in blood, while keeping the size of the workshop manageable and productive. A
copy of "Analytical Performance Criteria for Lead Test Kits and Other Analytical Methods"
(Williams, Estes and Gutknecht, 1991) was sent to the invitees as a means of providing background
material supportive to the goals of the workshop.
Thirty-three representatives accepted the invitation to attend the workshop. These
representatives were sent a list of questions for discussion, "Principal Concerns for the Lead
Reference Materials Workshop," which is presented in Appendix A. Upon arrival, attendees
received a notebook containing the following information:
Workshop Program
- Agenda
- List of Attendees
Available Reference Materials
Description of Standard Methods for Lead
Performance Criteria and Reports
- Tables from "Analytical Performance Criteria
for Lead Test Kits and Other Analytical Methods"
(Williams, Estes, and Gutknecht, 1991).
- Chapter 4: "Guidelines for Hazard Identification
and Abatement in Public and Indian Housing" (U.S. Department
of Housing and Urban Development, April, 1990).
- Tables from "Comprehensive and Workable Plan for the Abatement
of Lead-Based Paint in Privately Owned Housing"
(U.S. Department of Housing and Urban Development, December, 1990).
- "A Comparison of the Results of In-Situ Spot Tests
for the Presence of Lead in Paint Films using Sodium
Sulfide with the Results of Laboratory Measurement
of Lead Concentrations in Paint Films using Flame
Atomic Spectroscopy" (Blackburn, 1990).
The workshop began with a morning session of presentations of the status of available
reference materials and measurement methodologies. (See workshop agenda presented on page 1-
4.) In the afternoon, the attendees met in subgroups (listed on page 1-5) to discuss specific
methodologies (AAS/ICP, XRF, Field Test Kits) and reference material requirements. At the end
1-2
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of the first day, all attendees reconvened to assess progress of the subgroups. The subgroups
reconvened the morning of May 14, and all attendees met together again during the afternoon of
May 14 to present conclusions and recommendations.
1-3
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AGENDA FOR LEAD REFERENCE MATERIALS WORKSHOP
MAY 13-14,1991
EPA HEADQUARTERS, WASHINGTON, DC
Time
Day 1 - May 13
9:00 a.m.
9:15 a.m.
9:30 a.m.
9:50 a.m.
10:10 a.m.
10:30 a.m.
10-50 a.m.
11:10 a.m.
11-30 a.m.
11:50 a.m.
12:00 noon
1:00-3:00 p.m.
3:00-4:00 p.m.
Day 2 - May 14
9:00-11:30 a.m.
11:30 a.m. - 1:00 p.m.
1:00-2:00 p.m.
2:00-4:00 p.m.
Speaker
Joe Breen (OTS)
Jim DeVoe (NIST)
Bill Gutknecht (RT1)
Topic
Introduction and Welcome
Need for Reference Materials
Health-Based Performance Criteria,
Regulations and Other Driving Forces
Portable XRF
Laboratory XRF
ICP/AAS
Field Test Kits
Blood Test
Direction for Subgroup Activities
Mary McKnight (NIST)
Hal Vincent (EMSL-LV)
Break
Gary Dewalt (MRI)
Bfll Gutknecht (RTI)
Dan Paschal (CDC)
BenLim(OTS)
Lunch
Subgroup Meetings to Discuss Reference Material Requirements
Reports from Subgroups on Reference Material Requirements
Subgroup Meetings to Define and Finalize Reference Material Characteristics
and Requirements
Lunch
Subgroup Final Reports
Subgroup Chairman Committee Meeting
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Tentative Subgroup Assignments
for
Lead Reference Materials Workshop
May 13 -14,1991
Washington, DC
AAS/ICP/GFAA/ASV
J. Chisolm
J. DeVoe*
G. Dewalt
M. Epstein
T. Gills
P. Grohse
G. Guirguis
S. Guyaux
B. Lira**
W. Loseke
A. Marcus
P. Parsons
D. Paschal
S. Roda
E. Williams
XRF
M. Beard**
A. Bober
S. Dillman
J. Joseph
M. McKnight
J. Neefus
J. Schirmer
J. Simpson
H. Vincent*
D. von Lehmden
S. Weitz
FIELD TEST KITS
J. Breen
R. Cramer**
W. Gutknecht
S. Harper*
M. Huang
D. Jacobs
L. Smith
* Group Leader
** Assistant Group Leader
1-5
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Section 2
Summary of Presentations
Presentations were made to provide a background for the need for reference materials, the
current availability of reference materials and the status of the methodologies used for lead analysis.
These presentations were the basis for subgroup discussion. The presentations are summarized
below.
Joe Breen - Introductory Comments
Joe Breen presented a brief overview of EPA lead-based paint programs currently in progress
as technical support to HUD. He also briefly discussed the proposed Lead Exposure Reduction Act
of 1991 introduced by Senator Reid, Bill No. S.391, and its potential impact on EPA/NIST
responsibility for the preparation of lead reference materials. He then introduced the speakers as
follows:
Jim DeVoe/NIST - "The Need For Reference Materials."
Aspects of analytical chemistry quality assurance (ACQA) were discussed. Two
"components" of ACQA are determination of analytical variability and systematic error. These
components ensure consistency between labs and thus, reliability for decision making.
ACQA activities are generated through the use of two types of reference materials (RMs):
primary reference (standard reference materials, SRMs), and performance evaluation (PE)
standards. The characterization of the PE standards is less stringent and therefore the preparation is
less costly than that for SRMs; thus, PE standards can be regenerated frequently. Because method
development and intercomparison of methods are dependent upon the availability of reference
materials, the development of methods and RMs is clearly an interactive process.
The requirements and activities of reference material laboratories were discussed in the light
of the following:
a high level of ACQA,
preparation and distribution of PE standards,
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coordination and evaluation of round robin analysis results,
assistance to production lab in ACQA improvements, and
coordination of workshops on method development and requirements for RMs.
The question of privatization of RM preparation was raised. Jim DeVoe responded in the
affirmative, but added that the activity should be heavily supported by government agencies. RM
design considerations were discussed. These included: (1) purpose and requirements; (2) type; (3)
concentrations (e.g., values should bracket real sample values); (4) required total uncertainty; (5)
quantity; (6) distribution; and (7) cost.
As a rule, uncertainty in an SRM is 5 to 10 times less than the uncertainty usually established
for a PE standard. The most important criterion for a PE standard is well-characterized
homogeneity, so that each laboratory that uses the standard can analyze the same composition.
Overall accuracy of the measurement follows from the measurement of SRMs.
Fabrication considerations include:
availability on a continuing basis,
stability,
homogeneity,
drying studies,
packaging, and
evaluation of prototype.
The existing SRM for lead in paint (NIST SRM 1579) was produced in 1973, and has a lead
concentration of 11.87% (118,700 ppm). This level of lead is approximately 5 to 10 times greater
than a concentration appropriate to current abatement standards.
Dr. DeVoe indicated that primary reference standards for lead in the following media were in
preparation:
lead in bovine blood,
lead in powdered paint, and
lead in soil.
A new SRM for lead in paint film is being planned. Currently there are no PE standards
available for any of the principal media.
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William Gutknecht/RTI - "Health-Based Performance Criteria, Regulations
and Other Driving Forces."
Currently regulations for lead in environmental media are based upon the following:
instrumental limitations,
practicality for clearance, and
health effects.
Federal and State regulated levels for paint, as well as clearance levels for dust and levels in soil
considered to be hazardous, are given in Table 2-1.
The need for reference materials was underscored by the estimations of the numbers of
homes requiring testing/abatement. According to the HUD document, "Comprehensive and
Workable Plan for the Abatement of Lead-Based Paint in Privately Owned Housing" (Department
of Housing and Urban Development, December, 1990), more than 57 million dwellings in the U.S.
have lead in paint in excess of the abatement level, while the number of dwellings with lead in dust
in excess of the Federal clearance guidelines was reported to be greater than 10 million.
Finally, the limited number of different kinds of reference materials available was described.
In summary, the driving forces which would affect the development of new reference
materials were listed as:
levels related to health effects
levels related to regulations
precision requirements
large number of dwellings to be tested
current lack of reference materials.
Mary McKnight/NIST - "Portable XRF."
The existing instrumentation was discussed including the Warrington, Princeton Gamma
Tech (PGT) and Scitec models. Dr. McKnight noted that the Warrington and PGT models were
filter instruments while the Scitec model was a spectrum analyzer. It was noted that other models
were exhibited at the 1991 Pittsburgh Spectroscopy Conference.
The fundamentals of portable XRFs were briefly discussed, and the problems of variability
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Table 2-1. Concentrations Of Concern For Lead In Environmental Media
Medium
Concentration
Regulatory Agency Regulatory Guideline Rationale
Paint 1.0 mg/cm2
5000 jxg/g
600 ppm
Dual 200 jig/ft2
600 (ig/ft2
SOOpg/ft2
HUD
HUD
CPSC
HUD
HUD
HUD
Abatement
Abatement
"New" Paint
Clearance - floor
Clearance - window sill
Clearance - window sill
Instrumental
limitation
Impurity Level
Health, clearance
practicality
Clearance
practicality
Clearance
practicality
Soil
500-1000 ppm
CDC
Hazardous level;
contributes to
elevated PbB
Health
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of results due to substrate composition and variability among instruments were noted.
The current HUD paint film standards prepared by NIST contain lead chromate, lead sulfate
and lead molybdate and have total lead concentrations of 0.6,1.5 and 3.0 mg lead/cm2. Proposed
specifications for new film standards with concentrations of nominally 0.0,0.3,1.0,1.5 and 5.0 mg
lead/cm2 were presented. These films were projected to be available in a year, to have a coefficient
of variance of 2-3 percent, and to be durable in warm, humid environments.
Harold Vincent/EPA EMSL - Las Vegas - "Laboratory XRF."
The fundamentals of XRF were discussed. Most laboratory XRFs will not excite and cause
K-shell emission (approximately 100 KeV, about 7 times the energy of L-shell emission).
Therefore, laboratory XRFs are typically set to monitor L-shell emission frequencies. Other issues
such as (1) the ratio of the intensity of line to Compton Scatter, (2) effect of particle size, and (3)
accuracy versus precision were discussed.
The detection limits stated for portable (i.e., hand-held) instruments were described as 50-500
ppm and 5-10 ppm for "mobile" laboratory instruments (those that can be set up in a trailer).
RM parameter considerations were discribed as: (1) homogeneity; (2) particle size; (3) film
thickness; (4) spiking versus natural; (5) site-specific versus site typical; (6) density; and (7)
chemical composition.
The effect of sample thickness was also discussed. A 2 mm x 30 mm disk, approximately
1.4 g, was considered the optimum configuration for XRF measurement. Problems (i.e., a sample
that is too thin to "capture" all exciting X-rays) are associated with using less than 1.4 g.
XRF analysis of dust samples was briefly discussed. The dust matrix was described as being
similar to soil, but not to paint. The required quantity of dust for XRF was suggested to be 400 mg,
but it was noted that it was often difficult to obtain a 400 mg dust sample.
The uses of RMs for support of XRF analyses were summarized as follows: (1) instrument
calibration (and check); (2) traceability; (3) diagnostics; (4) quality laboratories; (5) quality sample
delivery groups; and (6) audits.
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Gary Dewalt/MRI - "ICP/AAS."
Fundamentals of ICP and AAS (flame and furnace) were discussed with respect to
development of reference materials. Interferences present for these instrumental techniques fall
into three major classifications: physical, chemical and spectral interferences. Physical
interferences, occurring primarily in the inlet systems of these instruments, can be controlled
through matrix matching of calibration standards and samples. Chemical interferences, though
common to graphite furnace AAS, are not generally encountered in ICP. Control of these
interferences is generally performed through addition of matrix modifiers to digested samples.
Spectral interferences, which are most significant for ICP analysis, are controlled using a variety of
background correction and spectral overlap correction methods. Reference materials should be
matrix-matched as closely as possible to real-world samples in order to demonstrate that analysis
data are not affected by the presence of these interferences.
Available digestion methods were summarized. These included a variety of wet and dry
digestion methods, as well as microwave methods.
Accuracy and precision of various AAS/ICP methods were discussed. In the absence of any
other quality control data for a group of samples, it was suggested that accuracies of 10 percent for
ICP and flame AAS measurements, and 20 percent for graphite furnace AAS measurements, are
expected for general analysis laboratories. These values were considered to be high by some
attendees.
William Gutknecht/RTI - "Field Test Kits."
The results of evaluation of five commercially available spot tests were presented. Four of
these are based on the reaction of lead with rhodizonate to form a pink color, while the fifth is
based on the reaction of lead with sulfide to form the dark lead sulfide. These test kits are:
Rhodizonate Sulfide
Based Based
LeadCheck (Hybrivet Systems) X
Verify LeadTest (Verify, Inc.) X
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Frandon Lead Alert (Frandon
Interprises) X
Merck EM Quant (EM Science) X
The Lead Detective (Innovative
Synthesis Corp.) - X
The principle conclusion of the study is that the kits are inaccurate because they solubilize
very little of the total lead available. Other conclusions of the study are as follows:
Kits are sensitive, responding to <1 jig Pb ,
High salt concentrations cause negative interference;
Dark colors of samples mask Lead Detective (sulfide) results;
There is poor sensitivity with "real-world" dust and soils;
There is adequate stability of color; and
Numerous problems are associated with usage by non-technical
staff.
Dave Jacobs/Georgia Tech - "Field Test Kits/Lead Paint"
Dave Jacobs distributed "A Preliminary Evaluation of Commercially-Available Lead-Based
Paint Field Test Kits," (Jacobs, 1991) that described an evaluation of the feasibility and utility of a
series of lead-based paint field test kits. The Georgia Tech study used paint film standards with
concentrations of nominally 0.0,0.1,1 and 4 mg lead/cm . It was noted that the calcium sulfate in
plaster substrates provided a significant interference. False negatives were far more prevalent than
false positives.
Dan Paschal/CDC - "Blood Test"
Dan Paschal described the determination of blood lead levels at the Centers for Disease
Control (CDC). Analyses are carried out using graphite furnace atomic absorption spectrometry
using either deuterium or Zeeman effect background correction. Interference from NaCl, common
to biological samples, is minimized by dilution.
Dr. Paschal indicated the new CDC level of concern as 10-15 (ig/dL.
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Section 3
AAS/ICP
3.1 Introduction
Lead reference materials development for atomic spectroscopic measurements were
discussed in the context of the following considerations/driving forces:
1. Range of lead concentrations typically found
2. Lead concentrations related to health effects and regulations
3. "Real-world" source vs synthetic composition
4. Matrices - physical form of sample (e.g., powder, chip)
5. Matrix compounds/interferences that must be considered
6. Reference material quality level - primary standard or performance evaluation standard
7. Cost related to reference material level (primary standard vs performance evaluation
standard)
8. Quantity requirements
9. Stability requirements
Analytical methodology, discussed from the standpoint of quantity required for analysis, was
considered a secondary driving force. The nature of "real-world" samples, health effects, and
regulations were considered to be the principal driving forces for the preparation of proposed
performance evaluation standards.
Several questions were raised. These included:
1. How will concentrations be verified?
2. What should be the uncertainty values?
3. Who should assume responsibility in development and marketing?
With these considerations in mind, each matrix type was discussed.
3.2 Blood
Biologically bound lead was considered necessary. Currently, blood reference materials are
3-1
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prepared from blood samples collected from cows orally dosed with lead nitrate. These samples
seem to provide an appropriate matrix. Levels of lead in blood standards (provided by dosing
animals with varying concentrations of lead nitrate) were proposed to reflect CDC levels of
concern, 5-25 (ig/dL, and the OSHA limit. The possibility of using freeze-dried blood was
discussed. The stability for lyophilized blood was reported to be 3 years, as opposed to 5 years for
frozen whole blood. Proposed levels are given in Table 3-1.
The quantity of blood specified for each unit of reference material should allow multiple
determinations. A quantity of 3 mL was considered to be suitable for graphite furnace atomic
absorption spectrometry (GFAAS) and anodic stripping voltammetry (ASV) determinations. It was
noted that CDC has historically provided reference materials at no cost to requesting laboratories.
The estimated cost per set of proposed reference materials would be about $100, with the cost
absorbed by the CDC or through a CDC/EPA interagency agreement.
3.3 Paint
The current methodology for determination of lead-in-paint samples was briefly discussed.
Most analytical problems associated with lead determination in paint appear to be dependent upon
the extractability of the lead species. Current methods for lead extraction include:
1. Dry ashing followed by wet digestion with HNO^ or
2. Wet digestion only with HNO3 or HNO3/H2O2
3. Microwave "digestion" with HNO3, HNC>3/HC1, or
The sensitivity of flame AAS and ICP is appropriate to the determination of lead in the
resulting digests using an analytical aliquot size of 250-mg. In order for a 250-mg aliquot to be
representative of the bulk sample, it was proposed that the material be ground to a particle size
equal to or less than 200 microns. It was believed that old paint (paint that has been removed from
houses at least 40 years old and has been subjected to "weathering" effects) should be used since its
lead extractability properties are different from new paint; e.g., post - 1978 paint containing less
than 600 ng/g lead, as required by the Consumer Product Safety Commission (CPSC). The max-
3-2
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Table 3-1. Proposed Lead Reference Standards
For AAS/ICP
Medium Composition
Levels Error. %
Rationale
Analytical
Aliquot Ref. Mat'l
Size AmnUUnit
Quantity
Projected
(Units)
Blood
w
Paint
Soil
Duet
Bovine-
"Biologically
bound" lead.
"Real world," old
paint obtained from
housing units >
40 yrs. old
from 3-4 locations.
Interferents such
as organics, Cr, and
Ti should be present
"Real-world" compo-
site from 3-4 cities;
gathered near roof
driplines.
"Real world"
composite from
3-4 cities
4-5
10
20
40
60
ug/dL + 10
ug/dL+10
ug/dL+10
ug/dL+10
ug/dL+10
600 ug/g+10
6000 ug/g + 10
60,000 ug/g + 10
20 ug/g ą20
1000 ug/g+10
6000 ug/g +10
60 ug/g + 20
500 ug/g +10
10,000 ug/g +10
Minimum measured level.
New defacto action level.
Approximates past CDC
action level (25 ug/dL).
Mandatory OSHA limit.
Upper levels -100.
Approx. CPSC limit.
Current abatement level.
Levels generally far lower
than current NIST1579
(11.87%)
0.1 mL
Lower observable limit
for rural area.
Upper limit CDC protective
level.
(Dewalt, 1991)
(Roda, 1991)
(Dewalt, 1991)
250 mg
250 mg
100 mg
SmLper
level
60,000
35 g per
level
5000
50 g per
level
5000
10 g per
level
6000
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Table 3-1 (Cont'd). Proposed Lead Reference Standards
For AAS/ICP
Medium Composition
Levels Error, % Rationale
Analytical
Aliquot Ref. Mat'l
Size Amnt./Unit
Quantity
Projected
(Units)
Dust Above sample
(wipe) deposited on
wipe, wipe folded
and submitted
for analysis
60 pg/g + 25
500 |ig/g+10
10,000 |ig/g ą10
Low level encountered for
ASV analysis of hand
wipes (Roda, 1991)
100 mg
4gper
level
5000
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imum lead content allowed by CPSC, 0.06 percent (600 ng/g), is based upon expected impurities in
the paint components, rather than lead additives. Other than variations in extractability, analytical
errors may result from ICP spectral interferences from metals such as titanium or chromium. It was
suggested that data for the concentrations of major and minor elements, along with expected trace
element interferences, be included as a part of the reference material certification. Proposed
parameters for paint are presented in Table 3-1.
3.4 Dust - Bulk (vacuumed)
The composition of "typical" dust samples (organic fibers, paint, hair and other biologicals,
soil, etc.) was discussed. Questions about the feasibility/difficulty in obtaining large quantities of
dust were raised, and, because of this, it was proposed that a synthetic dust be prepared from a
composite of soil and paint. Drawbacks to this approach were discussed. The chief concern was
that the lead forms in the "synthetic" material would not exhibit realistic extraction characteristics.
Tom Gills of NIST believed that it would be possible to collect adequate quantities of dust.
Consequently, it was suggested that "real-world" samples be collected from several (3-4) urban
sites. Typically, a minimum of 100 mg of dust is required for analysis by AAS. The workgroup
proposed that 5000 bottles of performance evaluation lead-in-dust be prepared, each containing
10 g of the reference material. Proposed parameters for bulk dust are given in Table 3-1.
3.5 Dust Wipes
After discussion of action levels and proposed reference material levels for lead in dust on
wipes, the question of a separate standard for dust wipe samples was considered. A number of
procedures for wiping a preweighed quantity of dust from a container were considered. A
suggestion that a weighed dust sample aliquot be placed on a smooth surface and the surface
"wiped" as quantitatively as possible was proposed. Another suggestion for digesting a preweighed
dust aliquot in its original container was proposed. However, pyrex containers were believed to be
too expensive; flint glass bottles containing wipes were not considered suitable for in-situ hot plate
3-5
-------
or microwave digestions. Finally it was suggested that a weighed aliquot (50 mg - 100 mg) of the
bulk dust sample be placed onto a blank wipe, the wipe folded to contain the dust, and the entire
sample (wipe plus dust) digested for analysis. Proposed parameters for dust for wipes are presented
in Table 3-1.
Current methods for preparation of wipe samples were summarized as the following general
types:
Ashing, wet digestion with HNO3/H2O2
Ashing, wet digestion with HNO3/H2O2/Ha
Leaching with HC1 to simulate stomach acid
It was concluded that further studies will be required to finalize procedures for the
preparation of reference materials for dust.
3.6 Soils
It was suggested that soil samples for reference material preparation be collected at roof drip
lines. Proposed standard levels are presented in Table 3-1. Again, a variety of extraction methods
are in use. Methods mentioned included a HNO3 leaching technique, EPA/OSW Method 3050
(and similar procedures), as well as two microwave methods using combinations of HNO3, HC1
and H2O2. The expected analytical aliquot size for most methods is 250-500 mg.
It was concluded that further studies will be required to finalize procedures for the
preparation of reference materials for soil.
3-6
-------
Section 4
Test Kits
4.1 Introduction
Test kits are available for testing for lead in solids. These kits are sensitive, but are not
accurate because they extract and respond to only a small fraction of the lead in the samples. In
order for the kits to be useful, the accuracy must be improved. Therefore, the objectives of the
subgroups were to identify reference materials for accurate test kits, currently not marketed. It was
recommended that these kits be used primarily for screening purposes. Eventual development of
two types of kits was suggested. These are kits for:
(1) the consumer, and
(2) a trained professional.
The consumer kit would offer a preliminary analysis (warning) that lead levels in solid
materials were potentially harmful. A second more rigorous kit, available to the professional only,
could be used for confirmatory analysis. The professional kit would be more accurate, principally
because of a more rigorous, though field-safe, method of sample extraction.
4.2 Paint
As noted, tests performed by Research Triangle Institute showed that the commercial test kits
on the market are not accurate. However, Miau Huang of the Consumer Product Safety
Commission reported that she has developed a test kit satisfactory for measurements at the level of
0.06 percent lead in paint on toys, furniture, ceramics and other consumer products.
The principle use of a test kit for paint on walls, ceilings, trim and other dwelling
components would be to determine the need for abatement. Since the current HUD level for
*y
abatement is 1.0 mg/cm^ or 5000 ng/g, it was decided that one reference paint material should be
>\
provided at 5000 pg/g. This material would also be satisfactory for those states using 0.7 mg/cm^
and 1.2 mg/cm2 as abatement decision levels. It was suggested that the solution resulting from
4-1
-------
dissolution of these reference materials be diluted to check samples at lower lead levels, e.g.,
concentrations equivalent to 0.1 mg/cm2 or below. Because some states exercise the option of 0.06
percent (the CPSC level) as an abatement level, it was decided that a paint reference material at 600
[ig/g should also be prepared. Again, the kits could be used to check lower concentrations by
dilution of the dissolved sample material. These parameters are presented in Table 4-1.
4.3 Dust
The appropriateness of measurement results expressed as loading (ug/ft ) vs. concentration
((ig/g) was discussed. Joe Schirmer believed that loading gave a better correlation to exposure.
Sharon Harper noted that modeling studies require lead levels to be expressed as concentration
((ig/g). The concentrations of prepared dust reference materials would necessarily be determined as
u,g lead/g medium.
There is not a predictable correlation between loading and concentration, and both have been
used to express levels of concern. CDC indicates 500 (ig/g as a lower level of concern for lead in
soil. Rufus Chaney (1990) suggested concentrations above 300 (ig/g to be a level of concern.
Studies have indicated "clean" dwellings to have lead levels of 114-125 ug/ft2 (Farfel and Chisolm,
1990). HUD has adopted clearance guidelines of 200 (ig/ft2, 500 ug/ft2 and 800 ug/ft2 for floors,
window sills and window wells, respectively. Given these health effects and regulatory levels, it
was proposed that two levels, 300 (ig/g and 1000 |ig/g, be used as target values for dust reference
materials, as shown in Table 4-1.
4.4 SoU
Lead in soil may come from a variety of sources including paint, gasoline, pesticides and
natural minerals. The health effects range of concern, like that of dust, has been proposed to be
150-450 (ig/g. The CDC states that the range of concern is 500 to 1000 (ig/g for soil.1 Thus it
proposed that reference materials of 300 and 1000 (ig/g be prepared. Proposed parameters for soil
are presented in Table 4-1.
4-2 AWBERG UBHARY U.o.
-------
Table 4-1. Proposed Lead Reference Standards for Test Kits
Medium Composition
Paint
Dust
Soil
"Real-world"
powder and/or films
composed of recast
"real-world" paint.
"Real-world" samples
collected from
several cities/sites.
"Real-world" samples
collected from
several cities/sites.
Levels Error, % Rationale
5000 iig/g+10
600 iig/g+10
300 Hg/g+10
1000 ng/g+10
300 Mg/g+10
1000 Hg/gą10
HUD abatement
level
CPSC level;
abatement level
for some states.
Approx. CDC lower
level of concern for
soil.
CDC upper level of
concern for soil.
Approx. CDC lower
level of concern
CDC upper level
ofconcern
Analytical
Aliquot
Size
260 mg;
1cm2
250 mg;
1cm2
100 mg
100 mg
250 mg
250 mg
Ref . Mat'l
Size/Unit
35 B
40cmz
35 s
40 cm^
10 g
10 g
30 g
30 g
Quantity
Projected
(Units)
6000
5000
5000
5000
6000
5000
-------
Section 5
X-Ray Fluorescence
5.1 Introduction
Reference materials are needed for field and laboratory X-ray fluorescence analyses. The
typical range of performance with these instruments is from 50-10,000 iig/g. Soil samples are
normally in the range of 50-600 ng/g but may be as high as 60,000 ng/g. Dust samples may have
lead levels up to 17,000 ng/g (Dewalt, 1991), though quantities of dust collected are typically low.
Therefore, even at high lead levels, the absolute amount of lead in the sample will be low; and
measurement of lead in dust requires use of the more sensitive laboratory XRF instrument.
5.2 Paint Films
It was noted that NIST is currently preparing standard paint films for HUD. Approximately
2000 sets of paint films having concentrations of nominally 0.0, 0.3, 1.0, 1.5 and 5.0 mg lead/cm2
will be prepared by May, 1992. These films will be used directly for testing instrument response
only. Calibration will require the use of various blank substrates behind the films or the
combination of films (for calibration at higher lead levels). Instrument linearity in the range of 0-3
y
rag/cm^ was suggested to be appropriate. Standard paint films are expected to be durable for 10
years if handled properly. Interferences such as As and Hg may be significant. In some cases,
AAS/ICP analyses may be required to confirm the presence of lead.
NIST noted that the relationship of wt/wt units to wt/area units is as follows:
= (mg/cm2)(l/t)(l/p)(103)
where t = thickness of film layer in cm
o
where p = density of matrix in
Therefore 1 mg lead/cm2 corresponds to 5000 ug/g or 0.5% (w/w) lead in a 40 mil paint film (7
o
layers) assuming that p for paint is 2 g paint per cm .
5-1
-------
Reference materials with known isotope ratios were discussed, and it was proposed that,
while these materials are useful for research, they may be beyond the scope of this task force.
Parameters are given in Table 5-1.
5.3 Soils
The expected performance range for soil samples was described as 50-10,000 ug/g. Several
standards are needed to determine the response curve. It was noted that lead levels in field samples
may reach 60,000 ug/g; other techniques, such as atomic absorption, could be used for samples
with concentrations exceeding 10,000 ug/g. Particle sizes may vary and be as high as 250 microns.
It was suggested that several matrices would be needed and that Rufus Chaney of the USDA be
consulted to determine the appropriate matrix categories. Proposed parameters based on available
information are presented in Table 5-1.
5.4 Dust
Lead-in-dust levels in potential reference materials were described as being similar to soils
(50-10,000 (ig/g). The matrix for such standards was described as being sufficiently variable and
complex so as to require further study of its physical and chemical characteristics. Because of
small sample sizes and sensitivity requirements, it was noted that analysis of dust samples can
presently be performed using laboratory XRF instruments only. Proposed parameters based on
available information are presented in Table 5-1.
5-2
-------
Table 5-1. Proposed Lead Reference Standards for XRF Analysis
Medium Composition
Paint
Film
New paint films
Levels Error,
0.3 mg/cm2 +10
1.0 mg/cm2 + 10
1.6 mg/cm2 ą 10
5.0 mg/cm2 +10
Rationale
Covers HUD and state
abatement decision levels
HUD action level
Values up to 20 mg/cm2
have been observed
Analytical
Aliquot Ref . Mat'l
Size Size/Unit
3" x 4" film Each
Quantity
Projected
(Units)
Minimum
of 3000-
4000
films,
reusable
in
Soils
Dusts
"Real-world" samples.
Particle size -
260 microns.
"Real-world" samples.
Possible "real-world"
sou/dust composite?
60 ng/g+10
10,000 |ig/gą10
60 ug/g+10
10,000 |ig/gą10
60 ng/g detection
limit for lab XRF
Maximum field sample
60,000 jig/g
17,000 has been observed
(Dewalt, 1991)
1-2 g
for lab XRF
1-2 g
for lab XRF
5-10 g per
level
6-10 g per
level
6000
6000
-------
Section 6
References
Blackburn, A.J., A Comparison of the Results of In-Situ Spot Tests for the Presence of Lead in
Paint Films Using Sodium Sulfide with the Results of Laboratory Measurement of Lead
Concentrations in Paint Films Using Flame Atomic Absorption Spectroscopy. HUD Contract HC-
5831,1990.
Chancy, R., Personal Communication, December, 1990.
Comprehensive and Workable Plan for the Abatement of Lead-Based Paint in Privately Owned
Housing. A Report to Congress. U.S. Department of Housing and Urban Development,
Washington, D.C., December, 1990.
Dewalt, G., Personal Communication at Lead Reference Materials Workshop, May, 1991.
Farfel, M.R. and Chisolm, J.J., "Health and Environmental Outcomes of Traditional and Modified
Practices for Abatement of Residential Lead-Based Paint", American Journal of Public Health.
1990, 80(10^:1240-1245.
Jacobs, D.E., A Preliminary Evaluation of Commercially-Available Lead-Based Paint Field Test
Kits. EPA Contract OD4913NAEX, May, 1991.
Lead-Based Paint: Interim Guidelines for Hazard Identification and Abatement in Public and
Indian Housing. U.S. Department of Housing and Urban Development, Washington, D.C., April,
1990.
Roda, S., Personal Communication at Lead Reference Materials Workshop, May, 1991.
Williams, E. E., Estes, E.D., and Gutknecht, W.F., Analytical Performance Criteria for Lead Test
Kits and Other Analytical Methods. EPA Contract 68-02-4550, February, 1991.
6-1
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APPENDIX A
List of
"Principal Concerns
for the
Lead Reference Materials Workshop"
Sent to
Potential Attendees
-------
PRINCIPAL CONCERNS
FOR THE
LEAD REFERENCE MATERIALS WORKSHOP
I. CONCERNS WITH METHODOLOGY
A. What IB the status of each of the principal methodologies (XRF, AA,
ICP, ASV) for determination of lead in paint, soil and dust? Accuracy?
Precision? Limit of detection?
B. What are specific problems for each method? Sample homogenization?
Sample dissolution?
C. What advances are needed for these existing methodologies and what
advances are expected in the near future?
D. What is the availability of the methods in laboratories around the
country?
E. What are the relative analysis costs and throughput?
F. How are we to accommodate emerging measurement technologies, e.g.,
biomarker field kits?
II. CONCERNS WITH REFERENCE MATERIAL DEVELOPMENT
A. Identification of the driving forces for reference material
development:
-------
Driven by proposed performance criteria?
Driven by adverse health effects?
Driven by real-world sample characteristics?
Driven by regulations?
SHOULD NOT BE DRIVEN by analytical methodology?
B. General concerns with reference material selection:
What are the "normal" real-world concentration ranges? The
table following this page should be filled in as a guide in
determining compatibility of performance criteria, real-world
concentrations and methodologies
Variation in lead concentration, lead speciation, matrix (paint,
dust, soil) composition with geographic source, urban vs. rural
source, private vs. public housing, age of housing?
Should the reference materials be blended from a variety of
sources so as to be "universal"? That is, how do we assure that
the materials are "representative" of the real world?
How many different concentrations should be prepared?
-------
How should the concentrations be verified? What would be
acceptable values for the ranges of uncertainty for these
materials?
How much material should be prepared?
What is the role of NIST SRM's and EPA's Reference Materials
Repository?
What is the role of the private sector in development and
marketing?
C. Paint - Specific concerns with reference material selection:
How should the material be collected?
What should the physical form be? Films? Chips? Powder?
How should the material be homogenized?
D. Dust Specific concerns with reference material selection:
What kind of dust should be collected? House dust? Street dust?
-------
How should the reference material dust be collected when many
kinds of dust collection methods (i.e., vacuum, hand-press, foam
roller, wipe) are being used?
How should the dust be prepared? Filtered? Homogenized?
E. Soil - Specific concerns with reference material selection:
What kinds of soil should be collected? Dwelling drip-line soil?
Playground soil? Soils ao\jacent to streets and highways?
Landfill soils?
How should the soil be collected? Digging? Scrapping?
How deep should the soil be taken?
How should the soil be prepared? Filtered? Homogenized?
-------
Reference Material Requirements
A. Concentration in rang* of performance criteria
B. Concentration In rang* of field samples
C. Concentration in linear range of inotrunenUbon
0. Cofflponaalion for intertonncos founo in eample matrix
Field Kits
AA/ICP/GFAA
XRF
Bio Methods
Oust
A.
B.
C.
0.
Soil
A.
B.
C.
O.
Paint
New/Replacement
A.
B.
C.
0.
Abatement Stnd.
A.
B.
G.
D.
-------
APPENDIX B
List of Attendees
-------
LEAD REFERENCE MATERIALS WORKSHOP
May 13 - 14, 1991
ATTENDEES
Mr. Michael E. Beard
AREAL
MD 77, ERC Annex
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
(919) 541-2623
Mr. Alvln Sober
Chief, Division of Environmental Chemistry
Dept. of Health and Mental Hygiene
201 W. Preston
Baltimore, Md 21201
(3O1) 225-6200
Dr. Joseph Breen
Office of Toxic Substances
WSM, Room E309, TS-798
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, DC 20460
(202) 382-3569
Dr. Julian Chlsolm
The Kennedy Institute for Handicapped Children
707 N. Broadway
Baltimore, MD 21205
(301) 550-9035
Dr. Randal I Cramer
Office of Toxic Substances
WSM, Room E309, TS-798
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, DC 20460
(202) 382-3989
-------
Dr. Jim DeVoe
Chief, Inorganic Analytical Research Division
National Institute of Standards and Technology
U.S. Department of Commerce
Galthersburg, MD 20899
(301) 975-4144
Dr. Gary DewaIt
Midwest Research Institute
425 Volker Blvd.
Kansas City, Missouri 64110
(816) 753-7600, Ext. 27O
Ms. Susan Dl I I man
Office of Toxic Substances
WSM, Room E-309, TS-798
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, DC 20460
(202) 382-7195
Mr. Michael Epstein
National Institute of Standards and Technology
U.S. Department of Commerce
Galthersburg, MD 2O899
Mr. Tom Gills
Certification and Production Manager, Standard Reference Materials
National Institute of Standards and Technology
U.S. Department of Commerce
Galthersburg, MD 20899
(301) 975-2016
Mr . Peter Grohse
Supervisor, Trace Metals Analysis
Research Triangle Institute
Research Triangle Park, NC 27709
(919) 541-6897
Dr. Gulrguis Gulrguls
Director, California Dept. of Health
and Industrial Hygiene Laboratory
Proficiency Program
Air and Industrial Hygiene Laboratory
2151 Berkeley Way
Berkeley, California 94704
(415) 540-2829
-------
Dr. William F. Gutknecht
Manager, Environmental Chemistry Department
Research Triangle Institute
P. O. Box 12194
Research Triangle Park, NC 27709
(919) 541-6883
Ms. Susan Guyaux
Maryland Department of the .Environment
Lead Poisoning Prevention Division
2500 Broenlng Highway
Baltimore, MD 21224
(301) 631-3859
Ms. Sharon L. Harper
AREAL
MD-78, ERC
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
(919) 541-2443
Dr. Mlau Huang
Consumer Product Safety Commission
9620 Medical Center Drive, Suite 310
Rockvi Me, MD 20850
(301) 433-9420
Mr. David Jacobs
Georgia Tech Research Institute
Room 22, O'Keefe Building
Atlanta, GA 30332
(404) 894-8090
Dr . J. Mehsen Joseph
Director of Laboratories
Dept. of Health and Mental Hygiene
201 West Preston
Baltimore, MD 21201
(301) 225-6200
-------
Dr. Ben Llm
Office of Toxic Substances
WSM Room E309, TS-798
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, DC 20-460
(202) 382-3509
Mr. Warren A. Loseke
AREAL
MD-78, ERG
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
(919) 541-2173
Dr. AlIan Marcus
Applied Statistics and Computer Application Section
Battelle
P. O. Box 13758
Research Triangle Park, NC 27709
(919) 549-8970
Dr. Mary E. McKnlght
National Institute of Standards and Technology
U.S. Department of Commerce
Galthersburg, MD 20899
(301) 975-6714
Dr. John D. Neefus
Certified Industrial Hyglenlst
Research Triangle Institute
P. O. Box 12194
Research Triangle Park, NC 27709
(919) 541-6578
Dr. Patrick Parsons
Director, Lead Poisoning Laboratory
Wadsworth Center for Laboratories & Research
N.Y. State Department of Health
Albany, New York 122O1
(518) 474-5475
-------
Dr. Dan Paschal
Center for Environmental Health and Injury Control
Centers for Disease Control
1600 ClIfton Road
Mai I Stop F-18
Atlanta, GA 30333
(404) 488-4026
Ms. Sandy Roda
Department of Environmental Health
University of Cincinnati Medical Center
3223 Eden Ave.. ML-56
Cincinnati, OH 45267
(513) 558-1705
Dr. Joe SchIrmer
ECEE-DOH
P. O. Box 309
Madison, WS 53701
(608) 266-2670
Dr . JIm SImpson
Center for Environmental Health
Blood Lead Proficiency Testing
Childhood Lead Program
Centers for Disease Control
Koger Center, F-37
1600 ClIfton Road
Atlanta, GA 30338
(404) 488-4780
Ms. Lisa Smith
OERR (OS-230)
US Environmental Protection Agency
4O1 M. Street, SW
Washington, DC 20460
(202) 382-4830
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Dr. Harold Vincent
EMSL/LV
U.S. Environmental Protection Agency
P. O. BOX 93478
Las Vegas, NV 89193
(702) 798-2129
(702) 798-2107
Mr. Darryl J. von Lehmden
AREAL
MD 77, ERC Annex
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
(919) 541-2415
Mr . Steve Weitz
Dept. of Housing and Urban Development
Room 8136
451 Seventh St., S.W.
Washington, DC 2041O
(202) 708-4370
Ms. Em I Iy WI I I Iams
Research Triangle Institute
P. O. Box 12194
Research Triangle Park, NC 27709
(919) 541-6217
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