United States
Environmental Protection
Agency
Atmospheric Research and Exposure
Assessment Laboratory
Research Triangle Park, NC 27711
Office of Pollution Preven&on Final Draft
and Toxics June 1993
Washington, DC 20460
Research and Development
&EPA
Outreach to
Manufacturers of
Lead Test Kits
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OUTREACH TO MANUFACTURERS OF
LEAD TEST KITS
by
K. K. Luk
L. L, Hodson
W. F. Gutknecht
Prepared for
R. J. Cramer
Office of Pollution Prevention and Toxics
U.S. Environmental Protection Agency
Washington, DC
EPA Project Officers
S. L. Harper
M. E. Beard
Atmospheric Research and Exposure Assessment Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27709
EPA Contract No. 68-02-4550
RTI Project No. 91U-5960-040
June 1993
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DISCLAIMER
The information in this document has been funded wholly by the United States
Environmental Protection Agency under EPA Contract 68-02-4550 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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ACKNOWLEDGEMENTS
This document was prepared under the direction of Ms. Sharon L. Harper and Mr.
Michael E. Beard, Atmospheric Research and Exposure Assessment Laboratory (AREAL), U.S.
Environmental Protection Agency, Research Triangle Park, NC.
Special acknowledgement is given to Dr. R. J. Gamer, formerly with the Office of
Pollution Prevention and Toxics, U.S. Environmental Protection Agency, Washington, DC, for
his careful review.
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TABLE OF CONTENTS
Section Page No.
1.1 INTRODUCTION 1
2.0 OUTREACH TO MANUFACTURERS 2
2.1 APPROACH 2
2.2 INTERVIEW QUESTIONS 2
2.3 RESPONSES TO QUESTIONS 3
3.0 RESULTS, DISCUSSION AND RECOMMENDATIONS 8
4.0 REFERENCES 11
Appendix A. Letter Submitted to Test Kit Manufacturers Requesting
Review of Report and Responses to Questions
Appendix B. Additional Comments from HybriVet Systems
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SECTION 1
INTRODUCTION
An initial exploration of the general behavior and responsiveness of five lead test kits
commercially available as of the fall of 1990 was performed. The intent was simply to
obtain an initial overview of the responses of all the kits to the same limited number of
test parameters and materials.
Copies of a draft report of this investigation entitled "Evaluation of Lead Test Kits
for Analysis of Paint, Soil and Dust" were submitted to each test kit manufacturer in
October, 1991, both for their review and also to provide information which might be
valuable to the manufacturers for the purpose of improving their kits. The
manufacturers' identities were coded in this draft report. The manufacturers were then
contacted and sent a questionnaire regarding their product and plans for the future.
After the outreach was completed (spring 1992), the draft evaluation report was revised,
the manufacturers' names included, and the report published as "Investigation of Test
Kits for Detection of Lead in Paint, Soil and Dust," EPA 600/R-93/085.
The objective of this report is to present a discussion of the results of this outreach
to the test kit manufacturers.
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SECTION 2
OUTREACH TO MANUFACTURERS
2.1 APPROACH
Each manufacturer was asked to review a draft of the report, "Evaluation of Lead
Test Kits for Analysis of Paint, Soil and Dust,"1 and two RTT/EPA documents, "Options
for a Lead Analysis Laboratory Accreditation Program"2 and "Options for a Test Kit
Certification Program"3 and to provide comments on the test kit evaluation report. (See
Appendix A) A list of interview questions approved by the EPA Project Officer (See
Section 2.2) was included with these reports. The manufacturers were asked to prepare
responses to these questions that then would be discussed in either a telephone
conference call or in a face-to-face meeting. The manufacturers were contacted a month
after their receipt of the reports to schedule a conference. Telephone conferences were
chosen by the manufacturers for their convenience and cost saving.
Only three companies out of the five successfully completed the outreach process.
Verify, Inc. apparently is no longer in business and the Innovative Synthesis Corp. could
never be reached.
2.2 INTERVIEW QUESTIONS
The following questions were addressed to the five different manufacturers:
1. Would you like your company's name to appear in the final report?
2. Will your company provide a toll-free 800 number to respond to questions from
consumers?
3. Is your company planning to clarify the instructions for the kit based on the findings
of this study?
4. Is your company planning to provide instructions for disposal of the reagents and
used materials from the test kits, as well as instructions for cleanup of tested
surfaces?
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5. Will your company consider providing gloves with the test kit (at least one pair)?
6. What is your current production capacity?
7. For what market was your kit designed?
8. What percentage of your kits have been sold to homeowners?
9. Does your company plan to improve your present test kit or to develop a more
quantitative kit?
10. What type(s) of research would be helpful to further develop a more quantitative
kit?
11. Do you think reference materials will be helpful to you in developing a more
effective test kit? What materials would be needed?
12. Do you feel that independent verification of the performance of test kits is
needed? What agency or organization should be responsible? Would your
company support this effort?
2.3 RESPONSES TO QUESTIONS
Telephone conference calls were held with the three manufacturers that responded
to the request for additional information. The responses to each question are listed
below for Frandon Lead Alert (F), HybriVet LeadCheck (LC) and Merck EM Quant (M).
1. Would you like your company's name to appear in the final report?
F: No problem with name on the report.
LC: Yes, provided that our concerns and reservations on how the tests were
carried out are included in the report.
M: Yes, we would like our name to appear in the final report.
2. Will your company provide a toll-free 800 number to respond to questions from
consumers?
F: Company will provide toll-free 800 number.
LC: HybriVet Systems already provides an 800 number (1-800-262-LEAD) for our
consumers to use to order product (LeadCheck Swabs), or to ask questions
about the product. The 800 number has been in operation since spring, 1990.
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M: We already have a toll-free number.
3. Is your company planning to clarify the instructions for the kit based on the
findings of this study?
F: Yes, the company will try its best to clarify the instructions.
LC: HybriVet Systems had already planned to rewrite the Instruction Manual
before the results of this study were released. Most of the clarifications were
written in response to our customers' experiences over the past two years.
This study verified the need for many of title changes we made. A working
copy of the new instructions has been included for your review and comment.
M: Instructions can always be altered, if necessary.
4. Is your company planning to provide instructions for disposal of the reagents and
used materials from the test kits, as well as for cleanup of tested surfaces?
F: Already had instruction for disposal of reagents (flush down the drain with
water).
LC: LeadCheck Swabs do not contain any toxic or hazardous materials. Conse-
quently, the consumer is instructed to dispose of the used Swabs in their
normal trash receptacles. Our consumers are instructed to dean the test area
to remove dust and dirt prior to testing the surface with the Swab and
following the test, to clean-up any residual reagents and/or pink color with
their normal household cleaner.
M: Really does not apply to our kit.
5. Will your company consider providing gloves with the kit (at least one pair)?
F: Yes, will consider providing one pair of gloves.
LC: Since LeadCheck Swabs contain no hazardous or toxic substances, gloves are
not necessary to handle the Swabs. As a normal safety precaution, however,
we do encourage our customers to use common sense safety practices. For
example, they are instructed not to use the Swabs near food or while eating
or smoking, and to store the Swabs and confirmation card away from children.
M: Gloves aren't really needed.
6. What is your current production capacity?
F: Product capacity depends on demands, can be 100,000 or 20,000.
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LC: Current capacity allows for production of 30/000 kits per week. However,
production can be increased substantially if demand requires it.
M: Hard to answer. With an accurate forecast almost any demand can be met
7. For what market was your kit designed?
F: Kits designed for home use.
LC: LeadCheck Swabs were designed to serve both the consumer and industrial
markets as a screening tool to detect the presence of hazardous levels of lead
on any solid surface, including painted surfaces. Since LeadCheck Swabs are
a presumptive test for lead and not a quantitative test, they cannot take the
place of a professional inspection for lead. The product is used by some
inspectors, however, as an adjunct screening tool to the XRF. Since the Swabs
are sensitive to lead in dust, many lead abatement professionals in Massachu-
setts are using the Swabs to monitor their clean-up procedures. For this
purpose HybriVet Systems has worked out a special protocol for wiping a
square foot area, which detects amounts of lead in excess of 200 ug/sq. ft.
(amount of lead allowed/sq. ft. following abatement procedures). According
to Dave Renner (Middlesex Deleading, Marlboro, MA), following abatement
of lead paint, surfaces and floors are repeatedly washed with TSP until a
negative reading is obtained with the Swabs using our dust protocol. When
this procedure is followed, the area has passed inspection for clearance. Such
a practice avoids repeated clean-ups and reinspections for clearance purposes.
I have included the dust protocol designed for this purpose.
M: The market for which the kit was designed is a little difficult to define. The
kit is made in Germany by our parent company, Merck, and we aren't sure
what their original plans were. Our kits are marketed through laboratory
supply distribution and a host of regional dealers.
8. What percentage of your kits have been sold to homeowners? to professionals?
F: 98% were for home use.
LC: Our records indicate that 75% of our kits have been sold to homeowners and
25% have been sold to professionals.
M: Since our national distributors deal in laboratory supply, the vast majority
probably are professionals. Niche accounts may include some homeowners,
but very few.
9. Does your company plan to improve your present test kit or to develop a more
quantitative kit?
F: Yes, company is planning to develop a more quantitative test kit.
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LC: HybriVet Systems is always open to suggestions tor improvement of the
LeadCheck Swab product. The original LeadCheck Swab product, which
appeared on the market in February 1988, was redesigned and improved in
its present monoswab form and was first marketed in September 1990. The
patent for LeadCheck Swabs was issued on August 13, 1991. HybriVet
Systems does plan to further improve LeadCheck, primarily in the area of
more efficient procedures for the extraction of lead from surfaces prior to
reaction with the swabs. To assist in the accomplishment of these goals,
HybriVet Systems has submitted an SBER grant proposal to the EPA, entitled,
"Detection and Measurement of Lead in Lead-Based Paints: Development of
Field Test Kits." This Phase I SBIR grant proposes:
1. To develop a series of lead paint standards as tools for this study. A wide
variety of paints which use different binders, lead pigments, and lead dryers
will be made following old lead-based paint formulations.
2. To explore an exhaustive list of possible extraction solvents used in the paint
industry and in paint removal as possible solvent(s) to use directly in the
Swab configuration or as a pretreatment prior to the use of the Swab.
Recommendations for both the consumer and the professional user will be
made.
3. To examine other lead reactive reagents for improved sensitivity to lead
and/or stability for a quantitative test to be developed in a Phase IL applica-
tion.
M: Yes. There will probably be a whole product line of similar products, which
will include the use of a portable, hand-held instrument.
10. What type(s) of research would be helpful to further develop a more quantita-
tive kit?
F: Research material. No straight answer to what type of research.
LC: It would be extremely helpful to have a set of reference standards for lead-
based paint, soil and dust to use as tools and checks as we attempt to improve
on the performance of the Swabs. Although we propose to establish our own
lead-based paint standards in the Phase I SBIR grant to EPA, we would be
delighted to include any reference standards developed by either EPA or NIST
in our study as they became available.
M: Same answer as question 9.
11. Do you think reference materials will be helpful to you in developing a more
effective test kit? What materials would be needed?
F: Reference materials will be very helpful.
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LC: As indicated in #10, reference standards are indeed needed to develop more
effective test kits. Lead-based reference standards should include samples that
contain a variety of lead-pigments, lead driers and paint binders (linseed oil,
alkyds, epoxies, etc. that were commonly used in lead pigments prior to 1978).
Reference standards for dust and soil should also be prepared.
M: Reference materials may be more useful in helping the end user ascertain how
the kit is performing, or recognize what a positive reading would look like.
Do you feel that independent verification of the performance of a test kit is
needed? What agency or organization should be responsible? Would your
company support this effort?
F: Verification of the performance of test kits is good only if it will not delay the
progress of the development of the product. Probably EPA or RTI are
appropriate organizations for this.
LC: Yes, independent verification of the performance of the test kit is needed.
Such an independent verification of LeadCheck Swabs would assure our
customers that the kit does what we claim it can do. The EPA Center for
Environmental Measurements for Quality Assurance seems to be an appropri-
ate agency to review test kits. HybriVet Systems would both welcome and
support this effort.
M: We have already addressed our concerns regarding verification. The agency
who is enforcing the law is the one who should be responsible, i.e., the EPA.
There should be a separate classification for field test or pre-screening type
kits and once again this should not be compared to the quantisation achievable
with conventional analytical instrumentation.
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SECTION 3
RESULTS, DISCUSSION AND RECOMMENDATIONS
3.1 Summary of Results
Each of the three kit manufacturers that responded to the outreach effort indicated
that they considered the test kit evaluation report to be fair to their particular product.
Several suggestions were made for changes in the report. These have been considered
and changes made where appropriate. One change made was to note that anionic and
cationic interferences cannot be differentiated and that one can only speak of a "salt"
interference. Another was to note that the number of real-world samples available for
evaluation was small, which often resulted in large differences between the lead
concentration in one sample and the next lower and/or higher one. Additional
comments from HybriVet are presented in Appendix B.
The three companies all indicated a serious interest in being of service to their
customers through availability of a toll-free 800 number. This interest was also
demonstrated through their current plans or willingness to clarify the instructions
included with each kit. None of the manufacturers considered the reagents in their kits
to be hazardous. None thought laboratory gloves were needed, Frandon, HybriVet and
Merck all stated that they have the capability to manufacture as many kits as can be
sold.
The Frandon test kit is designed for home use while the HybriVet and Merck kits are
designed for both home and professional use. HybriVet is promoting their kit as an
adjunct screening tool to the XRF with their protocol for detection of more than 200
ug/sq. ft. of lead on surfaces.
All three manufacturers plan to develop and market quantitative kits. HybriVet is
seeking an EPA grant to perform needed research while Merck is turning to the parent
company in Germany for this development
All three manufacturers also stated that the availability of reference materials would
be extremely useful, both for development of new, quantitative kits and also as quality
8
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assurance materials for both qualitative and quantitative kits.
Finally, all three manufacturers agree that verification of test kit performance is
desirable. However, there were reservations about a verification process slowing
development and marketing of new products.
3.2 Discussion
As noted, outreach to the kit manufacturers has been beneficial to both the
manufacturers and the EPA. The manufacturers have been presented with data showing
the responses of their kits to a variety of laboratory-prepared and real-world lead-
containing materials. Both strengths and limitations have been identified. The
manufacturers have also been made aware of the needs of both the homeowner and the
professional tester as determined by EPA. The manufacturers are responding to these
needs both by improvement of their current kits and development of new, quantitative
kits. The EPA has also benefited as it now better understands the direction being taken
by manufacturers, and also their current needs. Among these needs are method
evaluation materials. Manufacturers have expressed a need for paint, soil and dust
materials which would be used both as quality control check samples for currently
available kits and as research materials to be used to assist in the development of new
kits. Paint, soil and dust materials representing the variety of samples and varying lead
concentrations expected in the field are seen as necessary. Another need recognized is
independent verification of the performance of modified and/or new test kits as they
become available in the market.
3.3 Recommendations
As a result of this outreach effort, several recommendations have been developed.
These are as follows:
(1) Maintain continous communications between EPA and test kit manufacturers.
Regular communication will allow EPA to alert the manufacturers to changes in
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policy, new regulations, and/or new findings about the health effects of lead that
might result in the manufacturers modifying or developing new products. Also,
as a result of this communication, EPA should be able to determine the needs for
research and development that would be most expediently performed by the
government.
(2) Develop a repository of paint, soil and dust method evaluation materials.
Outreach has shown a need for materials for both kit testing and kit development.
Paint, soil and dust materials are needed. The concentrations of lead in these
should reflect the levels of concern described in a report entitled "Proposed
Performance Criteria for Lead Test Kits and Other Methods"4 that are based on
regulations and health effects. Further more, the outreach has indicated that a
range of lead levels are needed with each material, with no large gaps between
the individual concentrations. Finally it was generally agreed through discussion
with the manufacturers that the materials should be real-world. This would
include paint chips on select substrates as well as powdered paint, and also dust
on wipes and filters as well as bulk dust.
(3) Establish a set of test kit performance specifications for both qualitative and
quantitative test kits.
Test kit manufacturers have indicated an interest in test kit performance
specifications for use in evaluating current kits and for development of new kits.
EPA has developed performance criteria, which are presented in Reference 1 of
this report and which may serve as the basis for specifications in the future. The
publication of specifications should assure that kits are available that do provide
measurements at levels of concern and that the results obtained can be used to
make decisions about risk, the need for abatement and others.
10
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SECTION 5
REFERENCES
1. Luk, K. K., L. L. Hodson, D. S. Smith, J. A. CKRourke and W. F. Gutknecht,
"Investigation of Test Kits for Detection of Lead in Paint, Soil and Dust," EPA
600/R-93/085, May 1993.
2. Estes,, E. D., E. E. Williams and W, F. Gutknecht, "Options for a Lead Analysis
Laboratory Accreditation Program," EPA Contract No. 68-02-4550, January 1991.
3. Estes, E. D., E. E. Williams and W. F. Gutknecht, "Options for a Test Kit Certification
Program," EPA Contract No. 68-02-4550, February 1991.
4. Williams, E. E., E. D. Estes and W. F. Gutknecht, "Analytical Performance Criteria for
Lead Test Kits and Other Analytical Methods," EPA Contract No. 68-02-4550,
February 1991.
11
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Appendix A
Letter Submitted to Test Kit
Manufacturers Requesting Review of
Report and Response to Questions
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RESEARCH TRIANGLE INSTITUTE
Center for Environmental Measurements and Quality Assurance
October 15, 1991
Dr. Donald M. Wallace
Frandon Enterprises, Inc.
"Frandon Lead Alert Kit"
S11 North 48th Street
Seattle, Washington 98103
Dear Dr. Wai lace:
Thank you for your Interest and willingness to review our study of five
lead test Kits on the market, Including your brand. Three reports prepared at
RTI are enclosed for your review and/or use. These are:
"Evaluation of Lead Test Kits for Analysis of Paint, Soil and Dust"
"Options for a Test Kit Certification Program"
"Analytical Performance Criteria for Lead Test Kits and Other Analytical
Methods"
Please review the test kit evaluation report and call us when you are
ready to discuss It. Hopefully your review will take no longer than three
weeks. We will then plan either a teleconference or meeting to review the
results. Also enclosed Is a set of questions which we would also like to
discuss during the teleconference or face-to-face meeting.
As we have told you on the phone, the goal of this work Is to help the
general public and also professionals In the lead field be aware of the
capabilities of available test kits and also to help test kit manufacturers to
Post Office Box 12194 Research Triangle Park, North Carolina 27709-2194
Telephone 919541-6914 Fax:919541-5929
A-l
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further Improve their Iclts and/or to develop new kits. Again, thank you, and
we look forward to your reply.
Sincerely,
Kate K. Luk
Research Chemist
WlI I lam F. Gutknecht
Department Manager
KKL:WFG:aca
CC: Dr. CJapp, PACE Environs
A-2
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Interview Questions With Lead Test Kit Manufacturers
1. Would you like your company's name to appear in the final
report ?
2. Will your company provide a toll-free 800 number to respond
to questions from consumers ?
3. Is your company planning to clarify the instructions for the
kit based on the findings of this study ?
4. Is your company planning to provide instructions for disposal
of the reagents and used materials from the test kits as well
as instructions for cleanup of tested surfaces ?
5. Will your company consider providing gloves with the kit (at
least one pair) ?
6. What is your current production capacity ?
7. For what market was your kit designed ?
8. What percentage of your kits have been sold to homeowners ?
to professionals ?
9. Does your company plan to improve your present test kit or to
develop a more quantitative kit ?
10. What type(s) of research would be helpful to further develop
a more quantitative kit ?
11. Do you think reference materials will be helpful to you in
developing a more effective test kit ? What materials would
be needed ?
12. Do you feel that independent verification of the performance
of test kits is needed ? What agency or organization should
be responsible ? Would your company support this effort ?
A-3
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RESEARCH TRIANGLE INSTITUTE
Center for Environmental Measurements and Quality Assurance
October 15, 1991
Dr. Meredith Hunter/Mr. Brad Evans
Hybrlvet Systems LeadCheck Swabs
4 Mechanic Street
Natlck, MA 01760
Dear Dr. Hunter and Mr. Evans:
Thank you for your Interest and willingness to review our study of five
lead test kits on the market, Including your brand. Three reports prepared at
RTI are enclosed for your review and/or use. These are:
"Evaluation of Lead Test Kits for Analysis of Paint, Soil and Dust"
"Options for a Test Kit Certification Program"
"Analytical Performance Criteria for Lead Test Kits and Other Analytical
Methods"
Please review the test kit evaluation report and call us when you are
ready to discuss It. Hopefully your review will take no longer than three
weeks. We will then plan either a teleconference or meeting to review the
results. Also enclosed Is a set of questions which we would also like to
discuss during the teleconference or face-to-face meeting.
As we have told you on the phone, the goal of this work Is to help the
general public and also professionals In the lead field be aware of the
capabilities of available test kits and also to help test kit manufacturers to
Post Office Box 12194 Research Triangle Park, North Carolina 27709-2194
Telephone 919 541-6914 Fax: 919 541-5929
A-4
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further Improve their kits and/or to develop new kits. Again, thank you, and
we look forward to your reply.
Sincerely,
KKL:WFG:aca
Kate K. Luk
Research Chemist
Wl 11 lam F. Gutknecht
Department Manager
A-5
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RESEARCH TRIANGLE INSTITUTE
Center for Environmental Measurements and Quality Assurance
October 15, 1991
Mr. Al Souther I and
E.M. Science
480 Democrat Rd.
Glbbstown, NJ 08027
Dear Mr. Souther I and:
Thank you for your Interest and willingness to review our study of five
lead test kits on the market, Including your brand. Three reports prepared at
RTI are enclosed for your review and/or use. These are:
"Evaluation of Lead Test Kits for Analysis of Paint, Soil and Dust"
"Options for a Test Kit Certification Program"
"Analytical Performance Criteria for Lead Test Kits and Other Analytical
Methods-
Please review the test kit evaluation report and call us when you are
ready to discuss It. Hopefully your review will take no longer than three
weeks. We will then plan either a teleconference or meeting to review the
results. Also enclosed Is a set of questions which we would also like to
discuss during the teleconference or face-to-face meeting.
As we have told you on the phone, the goal of this work is to help the
general public and also professionals In the lead field be aware of the
capabilities of available test kits and also to help test kit manufacturers to
Post Office Box 12194 Research Triangle Park, North Carolina 27709-2194
Telephone 919 541-6914 Fax: 919 541-5929
A-6
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further Improve their kits and/or to develop new kits. Again, thank you, and
we look forward to your reply.
Sincerely,
Kate K. Luk
Research Chemist
Wl11 lam F. Gutknecht
Department Manager
KKL:WFG:aca
A-7
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RESEARCH TRIANGLE INSTITUTE
Center for Environmental Measurements and Quality Assurance
October 15, 1991
Mr. Barry Soslnsky
Innovative Synthesis Corporation
"The Lead Detective"
1425 Beacon Street
Newton, MA 02168
Dear Mr. Soslnsky:
Thank you for your Interest and willingness to review our study of five
lead test kits on the market, Including your brand. Three reports prepared at
RTl are enclosed for your review and/or use. These are:
"Evaluation of Lead Test Kits for Analysis of Paint, Soil and Dust"
"Options for a Test Kit Certification Program"
"Analytical Performance Criteria for Lead Test Kits and Other Analytical
Methods"
Please review the test kit evaluation report and call us when you are
ready to discuss It. Hopefully your review will take no longer than three
weeks. We will then plan either a teleconference or meeting to review the
results. Also enclosed Is a set of questions which we would also like to
discuss during the teleconference or face-to-face meeting.
As we have told you on the phone, the goal of this work Is to help the
general public and also professionals In the lead field be aware of the
capabilities of available test kits and also to help test kit manufacturers to
Post Office Box 12194 Research Triangle Park, North Carolina 27709-2194
Teleohone 919541-6914 Fax:919541-5929
A-8
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further Improve their tclts and/or to develop new kits. Again, thank you, and
we look forward to your reply.
Sincerely,
Kate K. Lufc
Research Chemist
Wi I Mam F. Gutknecht
Department Manager
KKL:WFG:aca
A-9
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Appendix B
Additional Comments from
HybriVet Systems
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ADDITIONAL COMMENTS
1. The instructions listed in Table 1 for Test Kit A (LeadCheck) under Soil and Dust
are incorrect. The instructions we provide our customers tell them to first activate
the Swab and them rub it into a small sample of dust that has been collected onto
a piece of waxed paper. Under these conditions the Swab is very sensitive to small
amounts of lead-paint dust. Our protocol for extracting lead from soil involves an
overnight soak in concentrated lemon juice (citric acid), followed by an analysis of
a small drop of the lemon juice supernatant with an activated LeadCheck Swab.
We wondered if it would be possible to reevaluate dust and soil samples using the
protocols designed by Hybrivet Systems, Inc. for these matrices. We feel that the
results would indicate that LeadCheck Swabs are more sensitive for lead in dust
and soil than reported.
2. In the section entitled, 2.3 Metal Interference Studies, it is possible that the
reduced sensitivity found for lead acetate solutions may not be due to the presence
of the acetate ion. Under basic conditions, lead forms insoluble Pb(OH)2 and
precipitates out of solution. It is thus possible that the observed reduction in
sensitivity is NOT due to interference oy acetate ion. but simply the result of the
removal of available Pb+2 ion from solution in the form of insoluble Pb(OH)2. If
this interpretation is correct, then the amount of free Pb+2 in a solution of lead
acetate would decrease over time as the lead precipitates from solution as
Pb(OH)2.
3. In Table 4, we disagree with the interpretation of the reaction of "A original Kit"
(LeadCheck Swabs) with barium to be positive. Rhodizonate reacts with barium
to form an orange color quite distinct from the pink color observed for lead. Since
orange can be distinguished from pink, we hesitate to call this reaction positive.
4. In the absence of lead paint standards, we spiked paints with lead nitrate. With
these standards, LeadCheck Swabs were as sensitive to lead as was the S9dium
sulfide test (see enclosed Performance Characteristics Sheet). Tests designed to
indicate performance characteristics showed that the Swabs gave a clear positive
result at t).4% lead and a plus/minus result at 0.3% lead. These values are
conservative estimates. Consequently, we were surprized at RTI's findings that the
Swab did not activate 100% of the time until 1.9 mg/sq.in. It is possible that the
paint film used as a standard in the RTT study contained lead pigments such as
lead chromates that are less soluble or extractable than the usual lead carbonates
or lead oxides found in household lead-based paints. Also, it is possible that
certain paint binders form a "film" on the surface that is less penetrable by the acid
buffer supplied by the Swab. The instructions supplied with the LeadCheck kit
instruct me user to cut down through all layers of paint to the substrate, and to rub
the Swab into the cut out notch. Ifany one of the layers of paint contains lead, the
Swab will turn pink. It is possible that a fresh cut through the layer of paint
exposes a matrix that is more easily penetrated by the acid extraction supplied by
the Swabs. Retesting the paint film standard used by RTI after a fresh cut is made
may give the requisite sensitivities for lead.
B-l
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