Lead Exposure: New Findings for an Old Problem

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Interdisciplinary Approach to Combating Childhood
Lead Exposure
Health Professionals Presentation
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Lead serves no useful purpose in the human body,
and its presence in the body can lead to toxic
effects, regardless of the exposure pathway
ATSDR, 2007
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Objectives

• Identify and describe sources of lead exposure in
  our environment and community
• Explain the major routes of lead exposure
• Review current evidence-based findings on the
  effects of elevated lead levels throughout the
  lifespan
• Examine long-term effects of low level lead
  exposure pertaining to childhood,
  pregnancy/lactation, adults and oral health
• Discuss strategies health professionals can
  implement
• Discuss current recommendations for screening,
  treatment, and referral

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Presentation Outline

• Lead Basics
• Lead in the Body
• Review of the Literature
• Management Strategies

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Lead BasicsWhat is lead?

• Bluish grey heavy metal
• Industrial use
• No biologic/physiologic purpose
• CDC recommendations levels of 10µg/dL or
  greater are of concern
• This level is used for risk management and not
  a cutoff for toxic effects

CDC, 2005
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Lead BasicsHistory

• 4,000 BC
• 1st warnings - 2nd century B.C.E
• 1st described in the U.S. 1914
• Death
• Complete recovery
• Misconception disregarded in 1943
• Behavioral disorders, learning difficulties,
  school failures
• Phased out of paint and gasoline by late 1970s

Lead was used to sweeten wine in early Rome
Needleman, 2004
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Lead BasicsSources

• Environmental
• Dust, soil, paint, gasoline, water, toys,
  contaminated foods like home grown vegetables,
  flour, spices, calcium supplements
• Occupational/Hobbies
• Lead smelting, plumbers, mechanics, working with
  guns, shooting ranges, making of stained glass or
  blown glass, burning painted wood, home
  renovation
• Transferred in-utero through breast-milk
• Pica
• Dietary supplements

Woolf et al., 2007
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Lead BasicsSourcesEthnic Practices

• Home Remedies
• Azarcon
• Greta
• Pay-loo-ah
• Litargirio (Deodorant)
• Ayurvedic herbs
• Mexican candies and seasonings
• Lead glazed pottery
• Cosmetics kohl, surma, ceruse
• Childrens jewelry

Laraque Trasande, 2005 Woolf et al., 2007
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Lead BasicsRisk Factors

• Age
• 0-6 years
• Immigration/International Adoption
• Cigarette smoking
• Poverty
• Pre-1978 housing
• Poor nutrition (increases lead absorption)
• Low calcium, Low iron
• Ethnicity
• Socioeconomic status
• Pica

Woolf et al., 2007 Erickson Thompson, 2005
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Lead BasicsIncidenceNational Statistics

• 434,000 children age 1-5 have higher blood lead
  levels (BLLs) than 10 µg/dL
• Decreased incidence due to changes in lead content

Brody, 2000
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Lead BasicsIncidenceState Statistics

• In 2005, 1.5 children age 0-6 had BLLs of
  10µg/dL
• Decrease of 13, 000 children (1997) to 4,000
  children (2005)
• Higher- Mexican-American children

TXDSHS, 2005
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Lead BasicsSan Antonio

• 3rd in the state for elevated BLLs
• 17.6 - below poverty level
• 11.4 - houses are pre-1950
• 56.7 - houses are pre-1978
• Highest risk zip codes 78201-05, 78207, 78215)
• Screening
• Limited providers screen children lt6 yrs.
• No screening of pregnant women
• Children lt6yrs, tested in 2005
• San Antonio Tested (15,853) Elevated (99)
• Bexar County- Tested (19, 787) Elevated (167)

TXDSHS, 2005
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Presentation Outline

• Lead Basics
• Lead in the Body
• Review of the Literature
• Management Strategies

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Lead in the BodyThe Process

• Absorption
• Inhalation, swallowing, skin
• Children and pregnant women absorb 50 more lead
  than adults (10-15)
• Blood
• Vital organs
• Excretion
• Renal or biliary clearance (Biologic half-life
  estimated at 10years)
• Retention
• 3 major compartments Blood, soft tissues,
  mineralizing tissues

Papanikolaou et al., 2005
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Lead in the BodyRetention

• Blood
• Initial receptacle
• Reduction in erythrocyte lifespan
• Decrease in blood hemoglobin biosynthesis
• Microcytic hypochromic anemia
• Half life is 35 days
• 99 of lead found in red blood cells
• BLL is most reflective of recent or continued
  lead exposure

Basophilic stippling of erythrocytes (BSE)
Papanikolaou et al., 2005 Laraque Trasande,
2005
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Lead in the BodyRetention

• Soft Tissues
• 15 of absorbed lead is retained in the vital
  organs
• Liver is the largest repository of soft tissue
  lead (33), followed by the kidney cortex and
  medulla, pancreas, ovary, spleen, prostate,
  adrenal gland, brain, fat, testis, heart and
  skeletal muscles
• Children retain lead in soft tissue at a greater
  rate
• Half-life is approximately 40 days

Patrick, 2006
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Lead in the BodyRetention

• Mineralizing Tissues
• 85 of absorbed lead is stored in cortical bones
  and teeth
• Total body burden found in skeleton 95 in adults
  and 73 in children
• Half life is 20-30 yrs
• Physiological stress causes lead to reenter the
  blood

Papanikolaou et al., 2005
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Lead in the BodySymptoms
CDC, 1991
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Presentation Outline

• Lead Basics
• Lead in the Body
• Review of the Literature
• Childhood
• Pregnancy/Lactation
• Adulthood
• Oral Health
• Management Strategies

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Review of the LiteratureChildhood

• Central Nervous System
• Two basic mechanisms
• Interference with neurotransmission at the
  synapse
• Interference with cell adhesion molecules,
  causing disruption in cellular migration during
  critical periods of CNS development

Woolf et al., 2007
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Review of the LiteratureChildhood

• Cognitive Development
• Lanphear found
• Cognitive deficits occurring in BLL
• lt 5ug/dl
• 1ug/dl increase in BLL was associated with a
  decrease in memory, reasoning, reading and
  arithmetic.
• Researchers found
• Greatest decrease in I.Q. occurred at BLLs
  gt10ug/dL
• Lanphear et al. in a pooled analysis of 1333
  children suggested
• 9.2 point decline in IQ over the range of less
  than 1 to 30ug/dL

Lanphear et al., 2000 Canfield et al., 2003
Woolf et al., 2007 Lanphear et al. , 2005
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Review of the LiteratureChildhood

• Behavioral Pathology
• BLL of 10-24.9ug/dL
• Increased hyperactivity
• Distractibility
• Low frustration tolerance
• Increased fearfulness
• Social withdrawal
• Adolescence
• 7 x more likely not to graduate
• 6 x more likely to have reading disabilities
• Delinquency 4 times greater risk
• Strong association is seen between preschool BLL
  and crime trends
• Association between counties with high BLLs and
  elevated violent crime rates

Mendelsohn et al., 1998 Needleman et al., 2002
Stretsky Lynch, 2001 Nervin, 2007
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Review of the LiteraturePregnancy

• Lead mobilization
• BLL follows a U-shaped pattern
• Maternal serum lead levels increase in pregnancy
  (20-30)
• Gulson concluded
• BLL increased 20 throughout pregnancy
• 31 came from skeletal lead stores
• Largest transfer -first pregnancy
• Lead freely crosses the placenta

Gulson, 1997 Hackley Katz-Jacobson, 2003
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Review of the LiteraturePregnancy

• Poor pregnancy outcome
• Increased risk of spontaneous abortion and
  pregnancy complications
• BLLs may be higher in the fetus than in the
  mother
• Mean of 32 higher
• Transplacental lead flow is through the process
  of diffusion (uni-directional)
• Neonatal BLLs higher with inadequate maternal
  dietary calcium

Hertz-Picciotto, 2000 Lamadrid-Figueroa et al.,
2007 Markowitz Xiao-Ming, 2001 Shannon, 2003
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Review of the LiteraturePregnancy

• Pregnancy induced hypertension (PIH)
• PIH with BLL of 6.3 ug/dL or more
• Every doubling in BLL was associated with PIH
• 10-µg/g increase in calcaneus (heel) bone lead
  increased risk of PIH
• BLL consistently higher in women with PIH
• Whats the connection?
• Lead may cause abnormal renal and vascular
  function? PIH
• Calcium supplementation may be beneficial

Rabinowitz Bellinger, 1987 Sowers et al.,
2002
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Review of the LiteraturePregnancy

• In-utero lead exposure
• Immature fetal blood-brain barrier
• Begins to cross the placenta mid-pregnancy
• Storage in fetal bone, blood, and the liver
• Teratogenic effects
• No clear evidence

Gardella 2001 Needleman, 1984
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Review of the LiteratureLactation

• Lactation
• Maternal BLL increased after delivery
• Levels elevated until weaning
• Although a recent study showed low correlation of
  0.21-8.0 µgm/L
• Weight gain
• For each ug maternal bone lead, infants gained
  3.6g less than control group at one month of age

Manton et al., 2003 Ettinger, et al., 2004
Sanin et al., 2001
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Review of the LiteratureLactation

• Gulson found
• Lead in formula ranged from 0.07-11.4 ug/kg
• Lead in breast- milk ranged from 0.09-3.1 ug/kg
• Recommendations of formula over breast milk would
  not reduce lead exposure risk
• Calcium supplementation may reduce the lead
  concentration in the breast milk by 5-10

Gulson et al., 2001 Kosnett et al., 2007
Ettinger et al., 2004
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Review of the LiteratureAdults

• Women
• Menopause
• Period of rapid bone turn-over
• Higher BLLs in post-menopausal women
• Negative effect on cognition
• Men
• Lead workers in their 50s with history of
  occupational exposure 16 yrs. Prior
• Cognitive test results 5yrs. older than age
• Adults
• In community dwelling residents aged 50-70 years,
  increase in the tibia BLL were significantly
  associated with decrements of cognitive function
• May shorten lifespan ( levels 20-29ug/dL)
• 46 increase in all causes of mortality
• 39 increase in cardiovascular mortality
• 68 increase in cancer mortality

Silbergeld et al., 1988 Schwartz et al., 2000
Bellinger Needleman, 2003 Potula Kaye, 2006
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Review of the LiteratureOral Health

• Dental caries
• Epidemiology of lead poisoning overlaps the
  epidemiology of dental caries.
• Data from several epidemiologic studies and
  animal based research support the concept that
  lead is a caries promoting element.
• 2 cross-sectional studies in Spain in 1994 and
  1996 identified lead as a risk factor for dental
  caries.
• An increase of 5 µg/dl in BLL was associated with
  nearly doubling of risk for dental caries.
• In 2006, Youravong et al. in children aged 6-11,
  that increased BLL was associated with caries in
  primary teeth, but not permanent teeth.

Brody et al., 1994 Gil F et al., 1996 Moss,
1999 Youravong et al., 2006
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Review of the LiteratureOral Health

• Potential Mechanisms
• Salivary gland function
• Protective properties
• Immunologic and bacteriostatic
• Adversely affects the ability of the gland to
  produce adequate amounts of saliva
• Enamel formation
• Defective enamel (enamel hypoplasia)
• Fluoride in saliva
• Reduces the preventive capacity of fluoride

Moss et al., 1999 Watson et al., 1997 Brudevold
et al., 1977 Gomes et al., 2004 Rao, 1984
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Review of the LiteratureOral Health

• Burtonians Line
• Lead results in a bluish red or deep blue linear
  pigmentation of the gingival margin
• Circulating lead reacts with sulphur ions
  released by oral bacteria
• Dental Plaque
• Levels of 2.7ppm up to 54.7ppm
• Lead line in pre-erupting teeth
• Lead affects odontoblast function

Watson et al., 1997 Youravong et al., 2005
Appleton, 1991
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Presentation Outline

• Lead Basics
• Lead in the Body
• Review of the Literature
• Management Strategies
• Screening
• Treatment

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Management StrategiesScreening

• CDC screening recommendations
• 1991 Universal screening for all children at 6
  mos. and 2 yrs.
• 1997 amendment and children at high risk
• TX Childhood Lead Poisoning Prevention Program
  (CLPPP) Recommendations
• Screen all children at 12 and 24 mos.

CDC, 2005 TXDSHS, 2005
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Management StrategiesScreening
Texas Childhood Lead Poisoning Prevention Program
Recommendations
TXCLPPP, 2007
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Management StrategiesScreening

• Strategic Plan to Eliminate Childhood Lead
  Poisoning by 2010
• Increase the number of Medicaid children being
  screened
• Medicaid (Texas Health Steps) requires child
  blood testing at 1 and 2 years of age
• Currently only 18 screened
• Record lead levels on vaccination card

TXCLPPP, 2007
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Management StrategiesScreening

• Blood lead level
• Measures acute lead exposure
• Venous sample preferred
• Capillary samples must be confirmed
• Other tests
• HGB HCT
• Iron status
• Iron deficiency can increase lead absorption
• FEP (free erythrocyte protoporphyrin)
• X-ray fluorescence spectroscopy

TXCLPPP, 2007
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Management StrategiesScreening

• What needs to be reported?
• All blood lead levels!
• Use form FO9-11709 Childhood Blood Lead Level
  Report
• Levels of 40 ug/dL or more
• Report by telephone
• immediately
• Report to
• Department of State Health Services in Austin
  (DSHS) 800-588-1248

TXCLPPP, 2007
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Management StrategiesTreatment
Summary of Recommendations for Children with
Confirmed (Venous) Elevated Blood Lead Levels
CDC, 2002
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Management StrategiesTreatment

• Identify and contain exposure source
• Forms and information for providers and parents
  available from TxDSHS website
• Seek professional assistance with management of
  lead paint (parents should not attempt to remove
  paint)
• Vacuum before washing floors to reduce dust
• Wash surfaces frequently with wet mops and damp
  rags
• Leave shoes at the door and work clothes at work
• Wash hands before eating, drinking, and after
  playing

AAP, 2005
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Management StrategiesTreatment

• Referral to Agencies That Can Assist
• Bexar County Childhood Lead Poisoning Prevention
  Program
• 210-207-6042
• San Antonio Neighborhood Action Department -
  210-207-7881
• San Antonio Housing Authority section 8 housing
  210-220-3200
• Department of State Health Services in Austin, TX
  800-588-1248
• City of San Antonio Health Department -
  210-207-8780
• Other Sources of information
• Centers for Disease Control www.cdc.gov
• Environmental Protection Agency www.epa.gov
• Southwest Center for Pediatric Environmental
  Health (U.T. Health Sciences in Tyler, TX) Toll
  free 1-888-901-5665, www.swcpeh.org

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Management StrategiesTreatment

• Chelation therapy
• Chelation therapy is not a cure for lead
  poisoning
• Consider for levels gt45ug/dL (controversial)
• Mechanism of action
• Commonly used agents
• Succimer
• EDTA
• Dimercaprol (BAL)
• D-penicillamine
• Side effects
• Safety in pregnancy?

Garcia Snodgrass, 2007 Papanikolaou et al.,
2005 Woolf et al., 2007
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Management StrategiesTreatment

• Nutrition
• Proper nutrition reduces lead absorption
• Regular meals/snacks
• Iron
• Calcium
• Vitamin C, E, B6
• Zinc
• Phosphorus
• Selenium
• ß Carotene
• Safe food handling
• Wash hands
• Run tap water cold for 1-2 minutes
• Use glass, stainless steel, plastic for food

Ahamed Siddiqui, 2007 Manton et al., 2003
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Management StrategiesTreatment

• Early Intervention
• Developmental surveillance
• Early enrichment programs
• Most effective when started prior to 3 yrs.
• Most effective when focused on child development
  as well as parenting skills

CDC, 2002
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A Final Thought To End On

• The cost of testing?
• Approximately 7
• The cost of not testing?
• The potential for
• Developmental delays
• Behavioral pathologies
• Cognitive damage
• Renal disease
• Cardiac disease
• Failure to thrive
• Etc.