Assessing and Managing the
Risks Associated With Eating
Seafood
Don Schaffner, Ph.D.
Professor and Extension Specialist
Rutgers - The State University of NJ
June 8, 2004
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Overview
- Understanding risk analysis, risk assessment and
risk management
- The steps in risk assessment
• Special attention focusing on exposure and doseresponse
• Using Methyl Mercury (MeHg) as an example
- Risk management
• Continue with MeHg example
• Show how FDA Foods Advisory Committee feedback
was used to improve the risk message
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Risk Analysis Components
- (Quantitative) Risk Assessment
• How big is the risk, what factors control the risk?
• Scientific process
- Risk Management
• What can we do about the risk?
• Political process
- Risk Communication
• How can we talk about the risk with affected individuals?
• Social and psychological process
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Risk Assessment
- Hazard Identification
• What agents, food(s) and people are involved?
- Exposure Analysis
• What is the chance of exposure?
• What is the level of exposure
- Dose-Response Analysis
• What is the human health effect of the exposure?
- Risk Characterization
• Complete picture of the assessed risk
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Hazard Identification
- Agent: Developing neurological system is very sensitive to
toxicity of methyl mercury
- Food: Mercury is a naturally occurring and also released into
the air through industrial pollution. Mercury can accumulate
in streams and oceans. Bacteria transform mercury into
methyl mercury. Fish absorb methyl mercury as they feed.
Methyl mercury builds up more in some fish than others
depending on what they eat.
- People: Women (of child-bearing age, who are pregnant, who
could become pregnant, who are nursing mothers) and young
children
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Dose-Response Analysis
- Reference dose (RfD) is an estimate
(with uncertainty spanning perhaps an
order of magnitude) of a daily oral
exposure to the human population
(including sensitive subgroups) that is
likely to be without appreciable risk
of deleterious effects during a
lifetime.
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Background on MeHg RfD
- EPA derived a MeHg RfD in 1995 based on a MeHg
poisoning incident in Iraq.
- Congress mandated (1997) that EPA fund a
National Research Council study to determine if
the RfD was scientifically justifiable
- NRC panel found RfD to be scientifically
justifiable (2000) but suggested EPA revisit the
issue using new 3 new studies
- The three new studies are the Seychelles Islands
study, Faroe Islands study and the New Zealand
study.
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Data used for RfD
- Seychelles Islands (-)
• 779 mother-infant pairs, infants followed from birth to 5.5
years, standardized neuropsychological endpoints, maternal hair
mercury concentrations.
- Faroe Islands (+)
• About 900 mother-infant pairs, Children tested w/ variety of
tasks at 7 years of age, cord blood mercury and maternal hair
mercury measured.
- New Zealand (+)
• 38 children of mothers with hair mercury levels during
pregnancy greater than 6 ppm matched with children whose
mothers had lower hair mercury concentrations, 237 children
were assessed on a number of neuropsychological endpoints
(similar to Seychelles study) at 6 years of age
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RfD determination
- There are several ways to determine a RfD, and
one is to used a Benchmark Dose (BMD)
- BMD calculations use a model to relate exposure
to effect, but to use it we need to know
• how low is “abnormal”
• If exposed, chance of becoming abnormal
- Add uncertainty factor
• Intra-human variability
- RfD was determined to be 0.1 ug/kg/day, which
corresponds to 5.8 mg MeHg/L blood
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Exposure assessment
- What foods are responsible for the exposure?
- What is the chance of a particular individual being
exposed?
- If exposed, what is the level of exposure?
- If enough data are available, a computer model can
be used to predict exposure, and to investigate
interventions.
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Exposure assessment model
Seafood
consumption
Diet-blood
ratio
MeHg by
Species
MeHg
Exposure
Blood-hair
ratio
MeHg Blood
Levels
MeHg Hair
Levels
Species
market share
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Exposure scenarios
- Divide fish into high, medium and low MeHg
species
- Run different computer simulations
including:
• No dietary exclusions at all
• Consumption from the Medium and Low groups,
but not High
• Consumption from the Medium and Low groups,
limiting the amount from the Medium group
• Consumption Low group, no Medium or High
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Exposure model summary
- Model appears to predict the
National Health and Nutrition
Examination Survey (NHANES) data
from the JAMA article
- Model will be peer reviewed, and can
be used to inform risk management
decisions
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Risk Management
- The results of the exposure and
dose-response assessments have
given us a picture of the situation
- Now we must weight competing issues
• Fish is…
• a good source of protein, provides important
nutrients and is generally affordable
• Fish may also contain substances that
are harmful to health
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Risk Management
0.10
Frequency
0.08
0.06
0.04
0.02
0.00
0
5
10
- About 8%
of at-risk
NHANES data
population
EPA RfD
Faroe BMDL
above the
RfD
- Objective:
reduce
this %,
and still
keep fish
15 20 55 60
in the diet
Hg in Blood (ppb)
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Improved risk message
- As a results of feedback FDA received from it’s
Foods Advisory Committee (FAC)
- FDA and EPA should combine their two
independent advisories
- Tell people what “eat a variety of fish” mean?
- People want to know about canned tuna… so tell
them!
- Unify commercial and recreational fish message
- Create specific advice for children
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Summary
- The risk analysis process and it’s
components
- The step in risk assessment, included
examples from exposure assessment and
dose-response for methyl mercury
- The nature of risk management and the
approach used by FDA and EPA in creating
their new (March 2004) advisory for
methyl mercury in fish for women and
children
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