environmental health
Changing the Pediatric Lead Reference Level:
What It Means for the Public Health Laboratory
by Jennifer Liebreich, MPH, senior specialist, Environmental Health
The accuracy of the test methods is
difficult to assess given that current
proficiency testing acceptance limits are
too wide. The current limit is +/- 4 μg/
dL or 10%, whichever is greater. While
individual laboratories may perform
significantly better than these national
averages, additional assessment of
national variability at the proposed
reference value is currently underway at
NCEH. A change in the acceptance limit
has been requested from the Centers for
Medicare and Medicaid Services and
is pending.
Before 2012, a “blood lead level of
concern” was considered 10 micrograms
per deciliter (μg/dL). But in 2012, the
US Centers for Disease Control and
Prevention (CDC) Advisory Committee
on Childhood Lead Poisoning Prevention
made a fundamental shift, saying
that there is no safe level of lead. It
established a statistical “reference
value” of 5 μg/dL—the 97.5 percentile
of the National Health and Nutrition
Examination Survey (NHANES) data
published in CDC’s National Exposure
Report—and recommended that the
reference value be reassessed with each
update to the report. In 2017, after review
of the most recent NHANES data, the
CDC Board of Scientific Counselors (BSC)
suggested that CDC adopt the new 97th
percentile of 3.5 μg/dL.
APHL’s Role
Analytical Concerns Around
Reduced Reference Levels
NHANES data is collected systematically
in optimal environments and analyzed
in a world-class laboratory at CDC’s
National Center for Environmental Health
(NCEH) to provide the highest quality
measurements. However, this rigorous
sampling and testing is not representative
of the conditions in pediatric offices,
hospitals and clinical laboratories.
As such, the variability in blood lead
measurements is greater than in
NHANES data.
According to an NCEH review of
proficiency data nationally, the three
techniques used to measure lead in blood
show great variability in precision at a
reference level of 5 μg/dL:
• Electrochemical Point of Care (PoC)
testing instruments = 5.0 +/- 1.8 μg/dL
• Graphite Furnace Atomic Absorption
(GFAAS) = 5.0 +/- 1.5 μg/dL
• Inductively Coupled Plasma Mass
Spectrometry (ICP-MS) = 5.0 +/- 0.97
μg/dL
PublicHealthLabs
@APHL
APHL’s Environmental Health Committee
identified lead as a re-emerging issue last
year and drafted a letter to former Acting
CDC Director Schuchat outlining the
analytical concerns related to lowering
the reference level. APHL received a
prompt response from NCEH Director Dr.
Patrick Breysse and has been in regular
contact with NCEH around this issue.
APHL submitted written testimony to the
BSC Lead Subcommittee and engaged the
American Academy of Pediatrics (AAP)
in Fall 2017. The subcommittee has also
begun drafting a position statement on
the lead issue.
Next Steps
CDC is committed to the recommended
reference level, issuing the decision
along with an MMWR article and
other guidance.
In May 2017, the US Food and Drug
Administration (FDA) reported that PoC
instruments may underestimate lead
concentration in venipuncture samples,
and recommended that venipuncture
should not be used with PoC instruments.
While Magellan Lead Care’s reporting limit
is 3.3 μg/dL, in March 2018 FDA found
that Becton-Dickinson made significant
changes to Ethylenediaminetetraacetic
acid (EDTA) vacutainers used in PoC lead
venipuncture samples, which affected
PoC instrument operation. APHL has been
following and reporting on federal actions
and recommendations on this issue.
APHL is and will be working with
CDC, NCEH, AAP and other partner
organizations to develop guidance for
laboratories, public health partners,
clinicians and parents. CDC guidance
could include draft language for adding
to laboratory reports, explaining what
the reduced reference level means, and
recommended actions around exposure
reduction and primary prevention.
Guidance could also address when a
confirmatory test would be recommended,
and whether such testing should be
conducted on a different platform. There
could be a real, increased need for more
lead testing capacity nationally, so being
clear about what a PoC test result means
and requiring confirmatory testing on a
different platform will be recommended
by APHL. n
APHL is assessing pediatric lead testing
capabilities nationally, both at the
state and local level, surveying current
capability and capacity, platforms used,
detection and reporting limits, resource
requirements and limitations, and any
possible billing complications. This
survey data will be used to determine
whether public health laboratories would
be interested in expanding current
pediatric lead testing or reestablishing
discontinued programs.
APHL.org
Spring 2018 LAB MATTERS
25