Health effects of blood lead levels lower than 10 mg/dl in children.

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American Journal of Public Health | January 2004, Vol 94, No. 1 8 | Letters
 LETTERS 
letter noting the absence of public involve-
ment in this process makes 2 relevant but, in
my opinion, inadequate points: (1) the public
had the opportunity to react to drafts of the
code on the American Public Health Associa-
tion Web site and (2) feedback was solicited
“from a broad range of stakeholders, includ-
ing the public.”
The response does not mention even one
non–health professional person or organiza-
tion that provided feedback or was specifi-
cally solicited for feedback. It also does not
explain why there was no non–health profes-
sional (“public”) person on the drafting com-
mittee. Sometime soon, I hope, this committee
will enrich the code with the experiences and
views of the public regarding the ethical as-
pects of public health practice.
Walter J. Lear, MD
About the Author
Requests for reprints should be sent to Walter J. Lear, MD,
Institute of Social Medicine and Community Health, 206
N 35th St, Philadelphia, PA 19104-2429 (e-mail:
wjlear@critpath.org).
WHAT LEVEL OF LEAD IN BLOOD IS
TOXIC FOR A CHILD?
Bernard states that current knowledge does
not warrant lowering the Centers for Disease
Control and Prevention’s (CDC’s) definition of
pediatric lead intoxication below the current
level of 10 µg/dL.1Bernard cites, in support,
economic considerations, inadequate health
risk data, and limited options for intervention.
As investigators of lead toxicity and pedia-
tricians who have treated poisoned children,
our position is that only health-based criteria
are acceptable for setting a health standard.
Cost–benefit analyses and policy issues are
peripheral and subordinate to the central
question: What level of lead in blood is toxic
for a child?
Over the past century, as knowledge of
lead toxicity has evolved, levels of lead in
blood once considered safe have been found
not to be. Governmental authorities have re-
sponded by lowering the definition of pedi-
atric lead poisoning.
Only 100 years ago, when childhood lead
poisoning was first described, physicians
doubted the very existence of the disease.
After the reality of pediatric lead poisoning
was accepted, the received doctrine was that
there were only 2 outcomes: death or com-
plete recovery. The first follow-up study of
children who had “recovered” from lead poi-
soning showed that almost all had severe
learning difficulties or behavior disorders.
Only children who displayed signs of en-
cephalopathy were then thought to show
residual brain damage. In the 1970s studies
showed that blood lead levels too low to
evoke symptoms produced IQ deficits, atten-
tional dysfunction, and slowed growth.
Consequently, the definition of lead toxic-
ity was lowered by the CDC, from 60 µg/dL
in the 1960s to 10 µg/dL in 1991. Two fac-
tors brought about this reduction: improved
investigational strategies and reduced back-
ground lead levels due to the removal of lead
from gasoline. The mean blood lead level in
this country in 1975 was 15.5 µg/dL. It is
now 2 µg/dL, permitting contrasts with sub-
jects with lead levels of 1 µg/dL.
Three studies now show that lead can cause
IQ deficits in children at levels below 10 µg/
dL.2–5Further, the slope of the IQ/lead re-
gression in these studies is steeper at levels
below 5 µg/dL than at higher levels. The
meaning of this surprising finding (found in all
3 studies) is clear: a large part of the damage
occurs at the lowest doses. Only partisans of
the lead industry quarrel with these data.
To protect America’s children, we must
again lower the officially defined standard to
conform to only the best science. Policy mat-
ters must adjust to the facts.
Herbert L. Needleman, MD
Philip J. Landrigan, MD, MSc
About the Authors
Herbert L. Needleman is with the Departments of Psychia-
try and Pediatrics, University of Pittsburgh School of Med-
icine, Pittsburgh, Pa. Philip J. Landrigan is with the De-
partment of Community and Preventive Medicine, Mount
Sinai School of Medicine, New York, NY.
Requests for reprints should be sent to Herbert L. Needle-
man, MD, Department of Psychiatry, Keystone Bldg, Suite
310, Pittsburgh, PA 15217 (e-mail: hlnlead@pitt.edu).
References
1. Bernard SM. Should the Centers for Disease Con-
trol and Prevention childhood lead poisoning interven-
tion level be lowered? Am J Public Health. 2003;93:
1253–1260.
2.
counting: methods for looking at the shapes and
strengths of associations. Neurotoxicology. 1993;14:
237–246.
Schwartz J. Beyond LOEL’s, p values, and vote
3.
lead exposure, intelligence and academic achievement:
a longterm followup study. Pediatrics. 1992;90:
855–861.
Bellinger DC, Stiles KM, Needleman HL. Lowlevel
4.
nitive deficits associated with blood lead
concentrations <10 µg/dL in US children and adoles-
cents. Public Health Rep. 2000;115:521–529.
Lanphear BP, Dietrich K, Auinger P, Cox C. Cog-
5.
Cox C, Jusko TA, Lanphear BP. Intellectual impairment
in children with blood lead concentrations below 10
microgram per deciliter. N Engl J Med.
2003;348:1517–26.
Canfield RL, Henderson CR Jr, Cory-Slechta DA,
HEALTH EFFECTS OF BLOOD LEAD
LEVELS LOWER THAN 10 MG/DL
IN CHILDREN
The thoughtful commentary provided by
Bernard1is a welcome addition to delibera-
tions about whether the Centers for Disease
Control and Prevention (CDC) should re-
spond to recent reports of adverse effects of
blood lead levels (BLLs) lower than 10 µg/dL
in children by lowering the BLL at which in-
dividual intervention is recommended.2,3The
CDC’s Advisory Committee on Childhood
Lead Poisoning Prevention is reviewing the
scientific evidence of the health effects of
BLLs lower than 10 µg/dL in children. A
finding of adverse effects across a large num-
ber of studies will raise important questions
about what changes, if any, the CDC should
make in its recommendations for medical and
environmental management of individual
cases. Several suggested changes, including
Bernard’s suggestion that very young children
with BLLs above the national average for
young children be tested more frequently, de-
serve further consideration.
Bernard also advocates widespread educa-
tion about the dangers of lead, the use of
blood lead surveillance and other data (such
as housing data) to identify populations at
risk, and improved screening of children en-
rolled in Medicaid. We concur with these rec-
ommendations and have asked state and
local programs funded by the CDC to work
aggressively in these areas. We also agree

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January 2004, Vol 94, No. 1 | American Journal of Public Health Letters | 9
 LETTERS 
that control or elimination of lead hazards is
essential in “repeat offender” housing where
children with elevated BLLs have repeatedly
been identified.
Also relevant to these considerations is the
lack of effective interventions to lower ele-
vated BLLs.4,5Taken together with the recent
reports of health effects of BLLs lower than
10 µg/dL, these studies suggest that elimina-
tion of childhood lead exposure requires the
implementation of creative strategies for pri-
mary prevention. However, shifting our focus
to primary prevention does not require chang-
ing the intervention level or preclude using
this level as one tool for identifying popula-
tions of children at highest risk. In fact, it is ex-
tremely important that we continue to focus
our efforts on those populations. Moreover,
we believe that primary prevention efforts, in-
cluding effective partnerships with housing
and other agencies to direct scarce abatement
and prevention resources to high-risk neigh-
borhoods, should be our highest priority. Em-
phasizing primary prevention is the only way
we can achieve the nation’s 2010 health ob-
jective of eliminating childhood lead poisoning
as a public health problem.6
Mary Jean Brown, ScD, RN
Patrick J. Meehan, MD, MPH
About the Authors
The authors are with the National Center for Environmental
Health/Agency for Toxic Substances and Disease Registry,
Centers for Disease Control and Prevention, Atlanta, Ga.
Requests for reprints should be sent to Mary Jean Brown,
ScD, RN, Lead Poisoning Prevention Branch, Mail Stop
F-30, 4770 Buford Hwy NE, Atlanta, GA 30341 (e-mail:
mjb5@cdc.gov).
References
1. Bernard SM. Should the Centers for Disease Con-
trol and Prevention childhood lead poisoning interven-
tion level be lowered? Am J Public Health. 2003;93:
1253–1260.
2.
Cox C, Jusko TA, Lanphear BP. Intellectual impairment
in children with blood lead concentrations below 10 µg
per deciliter. N Engl J Med. 2003;348:1517–1526.
Canfield RL, Henderson CR Jr, Cory-Slechta DA,
3.
pairment and blood lead levels. N Engl J Med. 2003;
349:502.
Bellinger DC, Needleman HL. Intellectual im-
4.
prevention of childhood lead exposure: a randomized
trial of dust control. Pediatrics. 1999;103:772–777.
Lanphear BP, Howard C, Eberly S, et al. Primary
5.
of chelation therapy with succimer on neuropsychologi-
Rogan WJ, Dietrich KN, Ware JH, et al. The effect
cal development in children exposed to lead. N Engl J
Med. 2001;344:1421–1426.
6.
Healthy People 2010. 2nd ed. Washington, DC: US
Department of Health and Human Services; 2000.
BERNARD RESPONDS
I appreciate the comments by Needleman
and Landrigan and by Brown and Meehan,
and I thank them for their valuable contri-
butions to the field of childhood lead poi-
soning prevention.
Needleman and Landrigan describe recent
research identifying adverse effects of lead
exposure resulting in childhood blood lead
levels (BLLs) below 10 µg/dL. This research
is also noted in my article, in which I stressed
the importance of continuing epidemiological
and toxicological studies in this area. I also set
forth there the history of the Centers for Dis-
ease Control and Prevention’s (CDC’s) inter-
vention level over the 20th century.
The question I addressed was not what
level of lead in blood is toxic to a child, but
whether lowering the CDC’s blood lead
screening and intervention level to 5 µg/dL
would result in a reduction of risk to children
now and in the future. Needleman and Lan-
drigan do not identify any interventions they
would recommend implementing for children
with BLLs between 5 µg/dL and the current
intervention level of 10 µg/dL. My analysis
suggests that the public health goals of pri-
mary and secondary prevention would best
be served by universal lead exposure risk
screening by means of a validated question-
naire, universal education of parents and
guardians about lead exposure risks, and in-
vigorated implementation and enforcement of
targeted screening efforts and requirements.
Renewed emphasis on these measures would
help protect the health of all lead-exposed
children, regardless of their BLLs.
I am encouraged that Brown and Meehan
concur in these recommendations. I also ap-
preciate the CDC’s willingness to consider my
recommendation that the time frame for re-
peat screening of infants with BLLs greater
than or equal to 5 µg/dL be shortened; the
current screening guidelines provide for only
annual screening, which may be inadequate
to prevent such children from becoming tod-
dlers with BLLs of 10 µg/dL or higher.
As Brown and Meehan note, the lack of ef-
fective interventions to lower elevated BLLs
and the recent studies showing adverse ef-
fects at BLLs lower than 10 µg/dL suggest
that an emphasis on primary prevention by
the CDC and other federal and state entities
is warranted. In this spirit, I recommended
that children be protected from lead exposure
through regulatory health-based standards set
with the goal of preventing childhood BLLs
even below those for which adverse health
impacts currently can be quantified.
Susan M. Bernard, JD, DrPH, MPH
About the Author
Requests for reprints should be sent to Susan M. Bernard,
JD, DrPH, MPH, c/o Johns Hopkins Bloombery School of
Public Health, 615 N Wolfe St, Suite 7041, Baltimore,
MD 21205 (e-mail: smbernard@verizon.net).