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Health Canada’s Blood Lead Response

Guidelines: implications for medical practice,

public health and occupational medicine

Tom Kosatsky, BCCDC

OEMAC 2012

Trends in action level for childhood lead poisoning

(1970–1990, CDC, USA)

Also,

Canada

1994

CDC lowers blood lead limits for

young children

In May 2012, the U.S. Centers for Disease Control and Prevention (CDC) updated its guidance on the level of lead in a child’s blood it considers harmful. Children with a blood lead level of 5 micrograms per deciliter (μg/dL) are considered by CDC to have more exposure to lead than 97.5% of their peers. This policy changed CDC’s long-standing guidance, which had recommended action at 10 μg/dL.

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“

“Draft 2011Guidelines

Linear models for each cohort study in the pooled analysis, adjusted for maternal IQ, HOME

score, maternal education, and birth weight. The figure represents the 5th to 95th percentile

of the concurrent blood lead level at the time of IQ testing.

“No safe level of

lead exposure has

been identified”

Log-linear model for concurrent blood lead concentration along with linear models for

concurrent blood lead levels among children with peak blood lead levels above and

below 10 μg/dL.

“No safe level of lead exposure has been identified”

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“Lead has toxic effects on many organ

systems at all life stages”

“Lead has toxic effects on many organ

systems at all life stages”

(Needleman, 1990)

Population significance of a 5 point IQ reduction

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“Current levels of environmental lead

exposure in Canada can be harmful”

Childhood Lead Poisoning from Commercially

Manufactured French Ceramic Dinnerware --- New York

City, 2003

“Subpopulations

already

experiencing

health

inequalities are

the most

vulnerable to

lead”

Lead Poisoning Associated with Ayurvedic

Medications --- Five States, 2000-2003

“Simple and inexpensive actions can reduce lead exposure”

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With regulation of lead in gasoline, child BLLs have plummeted

� “The role of the physician is to identify and manage

those individuals who are not fully benefiting from the

efforts of government and public health agencies to

reduce lead exposure in the general population.

� In order to identify patients with atypical blood lead

levels, it is necessary to select those for testing who are

most likely at risk. This practice is equivalent to case

finding where a “case” is a patient who has a blood lead

concentration that is greater than or equal to the 95th

percentile of the expected age specific distribution of

blood lead in the general population”.

“Who and When to Test?

�Patient reveals potential for lead-related health concerns

�Patient expresses concern about lead exposure

�Patient reveals presence of (selected) risk factors

Housing/ResidenceLiving in or regularly visiting older homes or buildings with chipping

paint or ongoing renovations or remodelling.

Infrequent or ineffective housekeeping that results in the

accumulation of dust.

Family and Behavioural FactorsHaving a sibling, housemate or playmate known to have had an

atypical blood lead level.

Living in poverty.

Newcomer from at risk countries

Food/Consumer ProductsUse of leaded crystal or pewter food ware.

Vegetarian or vegan diet (risk of low iron and calcium status).

Use of foreign made food, candies, cosmetics or holistic, herbal,

and alternative medicines or folk remedies that are not licensed for

sale in Canada (these items generally do not meet English and

French labelling requirements).”

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Figure illustrates the estimate of the 95th percentile of the blood lead

concentration in the general population (solid line) and the 95th percentile upper

confidence limit of the estimate (dashed line).

“What is the health risk?

Concentrations above 20 μg/dL (0.96 μmd/L) are

associated with overt symptoms and clinically

relevant outcomes.

An increase in blood lead levels from 1 to 15 mg/dL:

� Average reduction of 7 (95% confidence intervals

4 to 10) full

� scale IQ points in school-aged children.

� Average increase in adult systolic blood pressure

of 4-7 mm Hg

An increase in blood lead levels from 1 to 10 mg/dL:

� Average reduction of 6 (95% confidence intervals

4 to 9) full scale IQ points in school-aged children.

� Average increase in adult systolic blood pressure

of 3-4 mm Hg

An increase in blood lead levels from 1 to 5 mg/dL:

� Average reduction of 4 (95% confidence intervals

3 to 6) full scale IQ points in school-aged children.

� Average increase in adult systolic blood pressure

of 1-2 mm Hg

Few data on the potential health effects associated

with blood lead concentrations < 1 μg/dL since, until

recently, few people had low blood lead

concentrations”.

Management by Blood Lead Level

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“Follow these actions for all individuals:

� Provide nutritional advice on the value of

adequate calcium, iron, and vitamin C intake

to reduce absorption or increase the excretion

of lead.

� Provide patient with educational materials on

sources of environmental lead exposure and

reduction strategies. Check with your local

public health unit for their educational

materials”.

Age-specific estimates of the 95th Percentile Blood Lead Concentrations

Note: The data include US

NHANES 2007-2008 for ages

2 to 6 years combined with

Canadian CHMS data from 6

to 79 and considered

representative of the general

Canadian population.

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If blood lead concentration ≥ the 95th percentile

based on the age of your patient, and <20 μg/dL

(0.96 μmol/L), follow the recommendations for all

individuals and:

� Take an environmental lead exposure history in

order to identify and begin to manage risk

factors for elevated blood lead levels.

� Re-test blood lead in 90 days to determine any

temporal trend in the patient's blood lead

concentration.

If blood lead concentration persists ≥ the 95th

percentile for age of your patient, follow the

recommendations for all individuals and:

� Assess patient for iron status.

� Continue to monitor (every 90 days) until the

blood lead level is no longer > 95th percentile.

� Test blood lead concentrations of others living

in the same household.

� Notify the local public health authority if

community exposure source is suspected”.

For children of

5-18 years the 95th

percentile blood lead

is at or slightly

over the laboratory

detection limit

“Local public health inspectors have the skills and training to

assess community spaces, including child care centres and

schools, rental units and community housing to identify

potential sources of environmental lead exposure.”

“The challenge for the physician is to help the individual

identify the potential source(s) of lead that may be

causing the atypical blood lead levels.”

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Toxicokinetics of lead

Elimination of

transferred

maternal lead

Equilibrium

with bone

lead stores

“Exposure” is largely historic

The bad old days

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The many residual sources of lead

Challenge of

source

identification

Many educational and environmental

household interventions to prevent lead

exposure in children have been studied. This

review of 14 studies found that educational

and dust control interventions are not

effective in reducing blood lead levels of

young children. There is currently insufficient

evidence that soil abatement or combination

interventions reduce blood lead levels and

further studies need to address this.

Household interventions for preventing domestic

lead exposure in children

Cochrane Summariesbeta

Independent high-quality evidence for health care decision making

Yeoh B, Woolfenden S, Lanphear B, Ridley GF, Livingstone N

Published Online:

April 18, 2012

Ineffectiveness of interventions

Follow these actions for all individuals:

� Provide nutritional advice on the value of

adequate calcium, iron, and vitamin C

intake to reduce absorption or increase

the excretion of lead.

Managing a Child’s Nutrition

Although the effectiveness of nutritional

interventions has not been established, the

following recommendations are common sense

and are appropriate advice for all children,

including those with elevated BLLs:

• Consume adequate amounts of bioavailable

calcium and iron.

• Consume at least two servings daily of foods high

in vitamin C, such as fruits, vegetables,

and juices.

• Eat in areas that pose a low risk for lead

exposure; for example, at a table rather than on

the floor.

• Participate in the Special Supplemental Nutrition

Program for Women, Infants, and Children (WIC)

if the family is eligible. Recommendations from the

Advisory Committee on Lead Poisoning Prevention. CDC, 2002

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We found no statistically significant

relationships between the PbB concentrations

and micronutrient ((calcium, magnesium,

sodium, potassium, barium, strontium,

phosphorus, zinc, iron (limited data), and

copper)). In adults and older children with low

PbB concentrations and minimal exposure to

Pb, microntrient supplementation is probably

unnecessary.

Low Blood Lead Levels Do Not Appear to Be

Further Reduced by Dietary Supplements

Brian L. Gulson,1 Karen J. Mizon,1 Michael J. Korsch,2 and Alan J.

Taylor3 Environ Health Perspectives 2006 August; 114(8): 1186–1192.

ALSO Two-thirds of calcium supplements failed to meet the 1999 California criteria for

acceptable lead levels (1.5 µg/daily dose of calcium) in consumer products.

“

“

What went awry?

Why not treat at the

95th percentile?

1. Low analytic precision around the current 95th percentile BLL for critical age groups

2. BLL does not simply represent current exposure

3. Effective source identification is unlikely at sub-outlier BLLs

4. Recommended educational and environmental household interventions to prevent lead exposure in children are ineffective

5. Dietary supplementation is unlikely to reduce and may raise BLL

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Potential implications for occupational practice

• Inconsistency between action levels (ACGIH) for

workers versus the general population

• May spur more testing of current and former

workers as part of general medical practice

• Ineffective advice to workers to manage non-

occupational exposures

• Movement of occupational blood lead management

from regulatory to the medical practice/public health

domains

alternatives to the “n rmative approach” • Limit recommendations for testing to individuals likely to have a must-intervene blood lead

level (20 mcg/dL in the draft document) .

• In advising physicians, other than for patients with must-intervene blood lead levels, emphasize

universal rather than individual measures to lower blood lead.

• Provide physicians with the population distribution of blood lead by age and gender. Suggest

practical ways that patients who wish to do so can recognize sources and reduce their lead

exposure; differentiate this advice for infants, children, workers and older adults.

• Target for intervention those groups at highest levels of exposure, or in whom the

consequences of exposure are greatest. An example of the former would be new Canadians,

and of the latter women of childbearing age, where nutritional mitigation, and occasionally

environmental investigation and remediation, can prevent inter-generation transmission of

lead. Surveys are likely to be more effective than screening as a guide to finding these groups

and developing ways to reduce their exposure.

• Identify new and unusual sources by investigating children with blood lead levels over 10

mcg/dL and adults over 20-25mcg/dL, as at these levels there is a reasonable expectation that

an exposure source can be identified. Develop a national database to promote recognition of

emerging patterns.

• Support lead source identification and mitigation at the community level.

Tom Kosatsky*

BCCDC and NCCEH

tom.kosatsky@bccdc.ca

604 7072447

* Opinions expressed here are those of the author