Draft for February 5, 2007 CASAC consultation

Draft Assessment Plan
To Support the
Lead Renovation, Repair, and Painting Rule

U.S. EPA

Office of Pollution Prevention and Toxics
Washington, DC

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Introduction

The U.S. Environmental Protection Agency (EPA) has proposed new requirements to reduce
exposure to lead hazards created by renovation, repair, and painting activities that disturb lead-
based paint. The Federal Register Notice for the Lead Renovation, Repair, and Painting (LRRP)
proposed rule is available at: http://edocket.access.gpo.gov/2006/06-71.htm. This action
supports the attainment of the Federal government's goal of eliminating childhood lead poisoning
by 2010. The proposal would establish requirements for training renovators and dust sampling
technicians; certifying renovators, dust sampling technicians, and renovation firms; accrediting
providers of renovation and dust sampling technician training; and for renovation work practices.
These requirements would apply in "target housing," defined in section 401 of the Toxic
Substances Control Act (TSCA) as any housing constructed before 1978, except housing for the
elderly or persons with disabilities (unless any child under age 6 resides or is expected to reside
in such housing) or any 0-bedroom dwelling. Initially the rule would apply to all renovations for
compensation performed in target housing where a child with an increased blood lead level
resides, rental target housing built before 1960 and owner-occupied target housing built before
1960, unless, with respect to owner-occupied target housing, the person performing the
renovation obtains a statement signed by the owner-occupant that the renovation will occur in the
owner's residence and that no child under age 6 resides there. EPA proposed to phase in the
applicability of this proposal to all rental target housing and owner-occupied target housing built
in the years 1960 through 1977 where a child under age 6 resides.

The EPA is presently developing the final LRRP rule. In support of this rule, EPA's Office of
Pollution Prevention and Toxics (OPPT) is developing an assessment of the effect of lead
exposure following specific RRP activities on the neurocognitive function in children (as
measured by IQ). This assessment will also include RRP activities conducted in child-occupied
facilities (COF).1 The purpose of this draft assessment plan is to outline the scope, approaches,
and methods being proposed for this assessment. This proposed assessment plan is intended to
facilitate consultation with the CASAC for the purpose of obtaining advice on the overall scope,
approaches, and key issues in advance of the completion of such analyses and presentation of
results in the first draft of the assessment. Subsequent to CASAC review, the proposed
assessment plan may be revised by EPA to reflect EPA's understanding of CASAC comment.

Scope of the Assessment

The purpose of this assessment is to characterize the effects of lead exposure following specific
RRP activities on the neurocognitive function in children (as measured by IQ). The EPA
recently released the final Air Quality Criteria Document (AQCD) for lead (US EPA, 2006) that
provides an extensive analysis of the health effects associated with lead exposure. The AQCD is
used as the source for the hazard assessment in the current assessment. The exposure assessment
focuses on dust lead levels created by specific RRP activities such as door or window
replacements, or paint removal by scraping, burning or sanding. The assessment will include an

1 COFs are defined (see 40 CFR 745.223) as a building, or a portion of a building, constructed prior to 1978, visited
regularly by the same child, under age 6, on at least two different days within any week, provided that each day's
visit lasts at least 6 hours and the combined weekly visit lasts at least 6 hours, and the combined annual visits last at
least 60 hours. Examples of COFs are day-care centers, preschools, and kindergarten classrooms.

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analysis of dust lead levels created by specific RRP activities with and without the requirements
of the LRRP rule. For each RRP activity, a distribution of blood lead levels will be estimated for
children under age 6. Finally, for each of the specific RRP activities, the assessment will
characterize the distribution of IQ loss due to the resultant lead exposure. It is important to note
that the assessment is not intended to provide a characterization of IQ loss on a population basis.
It is only intended to provide estimations of IQ loss associated with specific RRP activities. This
information will then provide the basis for the subsequent economic analysis for the final LRRP
rule.

Uncertainty and variability analyses will be undertaken as the assessment is developed. For
example, analyses of exposure approaches will be presented in the exposure assessment, analyses
of the blood-lead models will be presented with the blood lead estimation, and analyses of IQ
models will be presented in the characterization of changes in children's IQ.

Hazard Identification

A detailed analysis of the health hazards associated with lead exposure is presented in the Air
Quality Criteria Document for Lead (EPA, 2006), and has been extensively peer-reviewed. This
assessment will utilize the AQCD, and will focus only on neurocognitive effects in children. As
described in the AQCD (EPA, 2006), neurocognitive effects in children are of particular concern
due to the levels at which they occur and the potential for lifelong impact. Neurocognitive
effects have been reported with remarkable consistency across numerous studies of various study
designs, populations studied, and developmental assessment protocols, even following
adjustment for many confounding factors. Consistently, studies have demonstrated dose-
response relationships. Children are particularly at risk due to sources of exposure, mode of
entry, rate of absorption and retention, and partitioning of lead in soft and hard tissues. The
neurocognitive effects reported in children appear to persist into adolescence and young
adulthood in the absence of marked reductions in environmental exposure to lead. In view of
these considerations, the effect of lead exposure on neurocognitive function in children (as
measured by IQ) has been selected as the endpoint for this assessment.

Exposure Assessment

Th q Environmental Field Sampling Study (EFSS) and the Characterization of Dust Lead Levels
After Renovation, Repair, and Painting (OPPT Dust Study) are the current and planned,
respectively, sources of information for the exposure assessment of lead. Another potential
source is the Lead-Safe Work Practices Survey Project Report recently submitted by the National
Association of Home Builders (NAHB).

The overall purpose of the EFSS was to assess lead disturbance and exposure associated with
various types of renovation and remodeling activities by measuring lead in air and dust before,
during, and after the conduct of targeted activities within housing units with confirmed lead-
based paint (EPA 1997). The EFSS was split into two primary components: one in which real
world RRP jobs, such as carpet removal and window replacement, were monitored; and one
involving a controlled study in which various RRP activities such as sawing, drilling, demolition,
sanding, and duct removal were monitored on surfaces containing lead-based paint. The

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controlled study also investigated the degree to which settled dust-lead loadings could be
reduced using either broom or standard vacuum cleanup on smooth cleanable surfaces. In total,
31 different workers participated in this study, with the real-world RRP jobs including workers
from the window and carpet removal/replacement industry, and with the controlled study
including certified abatement contractors. The results of the EFSS demonstrated that significant
lead loadings were generated by most of the different RRP activities pursued.

The OPPT Dust Study is currently in progress, and is anticipated to be completed in January,
2007. The OPPT Dust Study is investigating the comparative impact on dust lead levels from
use of the lead-safe work practices EPA has proposed and from baseline activities. The study is
also investigating the effectiveness of different components of the lead-safe work practices EPA
has proposed. There is an internal job component and an external job component. For interior
jobs, settled dust wipe samples and air monitoring samples will be taken for each job, each
cleaning step, and each cleaning verification step. For exterior jobs, dust wipe samples will be
collected.

The NAHB submitted the Lead-Safe Work Practices Survey Project Report in November 2006.
Its objective was to measure the lead dust levels generated during typical renovation/remodeling
(the Report's "R&R" is the equivalent of "RRP") activities to determine if routine RRP activities
increase lead dust levels in the work area and environs. In this project, air and surface wipe
samples were collected during 60 RRP activities performed by local professional RRP
contractors at five residential properties.

The first draft of the exposure assessment includes 1) exposure scenarios based on existing data
(without the OPPT dust study) and 2) exposure scenarios based on the OPPT dust study (to be
completed in full in the second draft of the exposure assessment). The RRP activities included in
the first draft of the exposure assessment are: renovating kitchen; three cutouts; replacing
windows; replacing exterior doors; scraping lead-based paint (LBP), interior flat component;
scraping LBP, interior door; replacing fascia boards; exterior LBP removal.

The specific exposure scenarios for the second draft of the exposure assessment are yet to be
determined, but scenarios that were used for the proposed LRRP rule were based on the EFSS
data and other existing data. These included:

Kitchen

Remodeled kitchen
Bathroom

Remodeled bathroom
Additions

Added Bathroom onto home
Added Kitchen onto home
Added Bedroom onto home
Added other inside room onto home
Bedroom created through structural changes
Other room created through structural changes
Bathroom created through structural changes

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Non-Room-Specific Wall/Ceiling

Added/replaced internal water pipes in home

Added/replaced electrical wiring, fuse boxes, or breaker switches in home

Added/replaced plumbing fixtures in home

Installed paneling or ceiling tiles

Added/replaced central air conditioning

Added/replaced built-in heating equipment

Other major improvements or repairs

Added/replaced security system in home

Non-Room-Specific Window/Door

Added/replaced doors/windows to home

Interior Painting

Whole Exterior

Added/Replaced siding on home

Contained Exterior

Added attached garage onto home

Added porch onto home

Added deck onto home

Added carport onto home

Added/replaced shed, detached garage, or other building

Exterior Painting

Exposure scenarios will include background soil and dust exposure pathways, as well as
exposures following various renovation, repair, and painting activities. Calculation of the
amount of exposure will follow a review of relevant literature/documents that pertain to changes
in lead loadings after abatement and renovation activities, though few abatement studies are
likely to be relevant to the RRP exposure assessment. The exposure assessment will fully
describe all assumptions, e.g., how dust/soil lead loadings were converted into lead
concentrations. The results of the exposure assessment will be suitable for use as input to the
blood lead models. If exposures change over time, (e.g., in the time following renovation, repair,
and painting activities), the exposure assessment will reflect this change.

The first draft of the exposure assessment will be available in time for a CASAC consultation in
early 2007. The first draft estimates exposures based on two methods for control of lead released
during the selected RRP activity scenarios: baseline controls, and full rule implementation
controls. Baseline control consists of basic sweep and vacuum cleaning, while full rule control
requires the use of plastic sheeting to protect surfaces and prevent dust migration, and HEPA
vacuum followed by wet wipe/mop cleaning.

The second draft of the exposure assessment will update the first draft of the exposure
assessment to address comments received from the CASAC review and to include data from the
OPPT Dust Study, the NAHB study, and other relevant data. The second draft of the exposure
assessment will complete in full the exposure scenarios based on the dust study that were
identified in the first draft of the exposure assessment.

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Estimating Blood Lead

The assessment will estimate blood lead level metrics for the specific RRP activities with and
without the requirements of the LRRP, and will, to the extent possible, include characterization
of uncertainty in these estimates. Once exposure levels in the form of either modeled intake
rates (e.g., for dietary items and indoor dust) or exposure concentrations (e.g., for ambient air)
have been generated, the next step is to model blood lead levels. The concentration of lead in
whole blood is the most commonly used measure, or biomarker, primarily because it is most
convenient and easily measured, but also because blood lead tends to be a good indicator of
recent exposures. Lead in long-term body stores (primarily bone) may also contribute to blood
lead concentrations and to the risk of adverse effects. Thus, most approaches for estimating
adverse effects take into account the biokinetics (i.e., uptake, deposition, mobilization, and
excretion) of lead in the body. Empirical approaches bypass the explicit modeling of biokinetics
and predict blood lead levels directly based on measures of lead exposure or intake.

Three models are being considered to estimate blood lead levels in children, the IEUBK model
(EPA, 1994), the Leggett model (Leggett et al., 1993), and an empirical model (Lanphear et al.,
1998). The IEUBK model (EPA 1994) is a well-evaluated and widely used EPA model for
predicting blood lead levels in children when exposures are expected to exceed 3 months to a
year. The Leggett et al. (1993) model, which is also a biokinetic model, can accommodate
shorter term exposures. The important features of the IEUBK and Leggett models are
highlighted in Table 1. Both models calculate time-averaged lead uptake (dose absorbed into
blood) over specified time periods, and model the transfer of the absorbed dose among various
biokinetic compartments. In the IEUBK, intake and uptake calculation modules for a range of
exposure pathways are built-in, with default exposure factors and absorptions fractions already
supplied. Multi-source and multi-pathway exposures are automatically combined to generate
estimated lead uptake. The intake module for the Leggett model is less refined than that for the
IEUBK; the user is required to supply estimates of total ingestion and inhalation pathway intake
(administered dose), summed across all exposure sources and media, although the computer
implementation has been adapted so that input is comparable to that for the IEUBK. Both the
IEUBK and Leggett have uptake modules that include pathway-specific absorption fractions, as
well as modules that simulate model respiratory tract deposition and ciliary transport of
particulate to the gastrointestinal tract. The Leggett model's treatment of both inhalation and
ingestion pathway absorption is somewhat more complex than that in the IEUBK.

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Table 1. Comparison of IEUBK and Leggett Model Characteristics

Biokinetic
Model

Model Inputs

Multipathway
Uptake
Estimation

Model Outputs

Support for Probabilistic
Estimates/Sensitivity
Analyses

IEUBK

Age-specific (annual)
air, water, dietary,
soil/dust lead
concentrations, age-
specific inhalation and
ingestion exposure
factors

Multi-source and
multi-pathway
intake/uptake
assessment inteeral
to model

Age-, pathway-
specific lead
uptakes, age-
specific individual
blood lead levels
(annual); age
specific blood lead
distributions

Lognormal approximation
of blood lead distribution,
batch processing,
automated sensitivity
analyses for individual
variables

Leggett

Age-specific acute or
chronic ingestion and
inhalation lead intake,
(daily) age-specific
ingestion, inhalation
absorption process
parameters

Ingestion and
inhalation
exposures from
different sources
must be combined
external to model:
front-end module
exists

Daily (or shorter)
Concentrations,
masses of lead in
blood and other
compartments, lead
excretion, clearance
for exposed
individual

None, must be done
external to model
algorithm

As noted earlier, an empirical model (the Lanphear model) for estimating blood lead levels in
children is also being considered. The Lanphear model (Lanphear et al., 1998) uses a regression-
based approach for predicting blood lead levels on the basis of environmental concentrations and
other variables. Application of the Lanphear model, if undertaken, will not be parallel to
applying the IEUBK or Leggett models. This model is being considered as a complement to the
biokinetic models, at the suggestion of the Science Advisory Board.

Regardless of the specific model(s) used, a distribution of blood lead levels will be estimated for
children under age 6 years for each specific RRP activity.

IQ Changes in Children

This assessment will characterize IQ changes in children for each specific RRP activity with
current cleanup conditions and those that would be in place following the LRRP rule. The
outputs from the blood lead models described above will be profiles of blood lead levels across
the ages of interest. The models will be summarized appropriate to the scenarios being
considered. The model outputs will be converted to metrics that can serve as suitable inputs for
the dose-response models. The dose-response models of Lanphear et al. (2005) and Canfield et
al. (2003) studies will be used for the modeling of IQ. As discussed in the AQCD (EPA, 2006),
these studies have high quality, good size, and have the potential for generalizability. In
addition, they have been subjected to rigorous peer and other external review.

Non-linearity in the relationship between blood lead levels and IQ scores, suggestive of higher
slopes at lower blood lead levels, has been identified. The form of the relationship is one feature
that may be explored in model uncertainty analyses, as will adjustment for covariates and other
model characteristics. Potential impacts of the most important covariates on change estimates
for particular RRP activities may be assessed through sensitivity analyses.

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Modeling of lead-related exposure and IQ is subject to a variety of sources of variability (e.g.,
residential location, type of renovation, dietary ingestion rates, lead uptake rates) as well as
sources of uncertainty (e.g., different blood lead models, different blood lead/IQ functions).
Because of data limitations and constraints, it is not feasible to develop confidence distributions
for many of the sources of parameter and model uncertainty identified for this analysis.
Therefore, rather than a comprehensive probabilistic uncertainty analysis, sensitivity analysis
techniques will be used to examine the impact of sources of uncertainty on exposure and IQ
results. Such techniques (entailing one-at-a-time variation) can be applied to examining the
contributions of different parameters, different models, and different sources and renovation
methods. Characterizing the impact of variability (e.g., of exposure magnitude, of exposure
duration) can also be explored via such techniques; probabilistic simulation is an adjunct that can
illuminate the impact of such intermediate steps as blood lead level derivation on the final
calculations.

REFERENCES

Atrium Environmental Health and Safety Services, LLC. 2006. Lead-Safe Work Practices
Survey Project Report. Prepared for NAHB (National Association of Home Builders).

Canfield, R.L., Henderson, C.R., Jr., Cory-Slechta, D.A., Cox, C., Jusko, T.A., and Lanphear,
B.P. 2003. Intellectual Impairment in Children with Blood Lead Concentrations below 10 |ig
per Deciliter. N Engl J Med 348:1517-1526.

EPA. 1994. Technical Support Document: Parameters and Equations Used in the Integrated
Exposure Uptake Biokinetic Model for Lead in Children (v.099d). Office of Solid Waste. EPA
540/R-94/040.

EPA. 1997. Lead Exposure Associated with Renovation and Remodeling Activities: Phase I,
Environmental Field Sampling Study (2 vols.). U.S. Environmental Protection Agency, Office
of Pollution Prevention and Toxics, EPA 747-R-96-007 and -008, NLIC #404 and #405,
available at http://www.epa.gOv/lead/pubs/leadtpbf.htm#Renovation.

EPA. 2006. Air Quality Criteria Document for Lead. National Center for Environmental
Assessment, Research Triangle Park.

http ://cfpub. epa. gov/ncea/cfm/recordi splay. cfm? deid= 15 8 823

EPA. 2007. Characterization of Dust Lead Levels After Renovation, Repair, and Painting. U.S.
Environmental Protection Agency, Office of Pollution Prevention and Toxics, EPA xxx,
available at http://www.epa.gov/lead/pubs/CASAC.htm

Lanphear, B.P., Matte, T.D., Rogers, J., Clickner, R.P., Dietz, B., Bornschein, R.L., Succop, P.,
Mahaffey, K.R., Dixon, S., Galke, W., Rabinowitz, M., Farfel, M., Rohde, C., Schwartz, J.,
Ashley, P., Jacobs, D.E. 1998. The Contribution of Lead-Contaminated House Dust and
Residential Soil to Children's Blood Lead Levels: A Pooled Analysis of 12 Epidemiologic
Studies. Environmental Research 79:51-68.

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Lanphear, B.P., Hornung, R., Khoury, J., Yolton, K., Baghurst, P., Bellinger, D.C., Canfield,
R.L., Dietrich, K.N., Bornschein, R., Greene, T., Rothenberg, S.J., Needleman, H.L., Schnaas,
L., Wasserman, G., Graziano, J., and Roberts, R. 2005. Low-Level Environmental Lead
Exposure and Children's Intellectual Function: an International Pooled Analysis. Environ Health
Perspect 113:894-899.

Leggett, R.W. 1993. An Age-Specific Kinetic Model of Lead Metabolism in Humans. Environ
Health Perspect 101:598-616.

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