Contaminants in Food – Hazards and Risks

P. Michael Bolger Ph.D., D.A.B.T.Washington, DC

Safety/Risk Assessment Paradigm

Risk Management

Risk Assessment

Science

Data

Inferences:1. Adversity2. Variability3. Uncertainty

What is safe? What is the Risk?

Model(Theory)

History of Safety/Risk Assessment

A. Lehman and O. Fitzhugh - Quarterly Bulletin of Assoc. Food & Drug Off. Vol. 28 (No.1): 33-35, 1954.

Based on “No Effect Level” or “No Observed Adverse Effect Level (NOAEL)”

10-fold safety factor (SF) based on a comparative analysis of fluorine and arsenic toxicity data in laboratory animals and humans.

Additional 10-fold SF to account for individual variation

Additional SF/UF up to 10 for differences in Dose Duration as well as Modifying Factors (MF) for inadequacy of data.

Non-Cancer - Dose-Response

Dose (mg/kg/day)

Resp

onse

(%)

50%

100%

LOAEL

Uncertainty Factor

RfD NOAEL

Safety/Risk Assessment

First step in an iterative safety/risk process. An answer to a simple yes or no question - safe or

unsafe. Acceptable Daily Intake (ADI) / Tolerable Daily

Intake (TDI) / Reference Dose (RfD) / Minimal Risk Level (MRL)

Useful for screening out trivial public health problems. Does not describe the degree of the problem

quantitatively or provide basis for gauging level of risk management remediation effort (e.g. , source identification, issuance of public health advisories, regulatory standards).

Methylmercury (MeHg) in Fish

Mass poisoning episodes in Japan in the 1960s resulted from environmental contamination and accumulation of methylmercury in fish.

Health effects included developmental abnormalities and death.

A second series of poisonings in Iraq in the 1970s resulted from treated grain contaminated with MeHg.

Several large scale epidemiological studies (Faroes and Seychelles islands) have investigated subtle fetal effects.

The level of MeHg in a given species of fish is dependent on the animal’s diet, size, and age. Generally, levels are below 0.4 mg/kg, but fish at the highest trophic levels may contain MeHg at levels above 5 mg/kg.

MeHg Hazards MeHg is readily absorbed from the GI tract and

preferentially binds to hemoglobin resulting in high erythrocyte to plasma ratios.

MeHg crosses blood: brain barrier and placenta, resulting in higher fetal brain MeHg concentrations as compared to the maternal levels.

Elimination is through the bile and feces, with neonatal animals having a lower excretory capacity as compared to adults.

Hair and blood levels are the primary biomarkers of exposure to MeHg.

Most sensitive endpoint in humans occurring at lowest doses is neurotoxicity which is dependent on dose and duration of exposure.

MeHg and IQ

-2

0

2

4

6

8

10

0 2 4 6 8 10

Hair MeHg [ppm]

Net

IQ

Dec

reas

e

Delayed Talking - Iraq

Delayed Walking - Iraq

Ryan - IQ - Faroe Islands

Ryan - IQ - Seychelles

Ryan - IQ - New Zealand

Cohen - IQ - Faroe Islands -LogCohen - IQ - Faroe Islands -LinearCohen - IQ - New Zealand

Cohen - IQ - Seychelles

Female Blood Mercury Levels in US Population in Relation to Health Screening Values (2009–2010)

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Fetal Neurodevelopment: Net Effect Modeling Results

Summary Net adverse effects are probable for diets with

high MeHg fish. Because most commercial fish are low in MeHg,

most U.S. consumers experience a net benefit from commercial fish consumption.

Over 12 oz. fish/week can result and for most people does result in a net benefit. However, the size of the benefit is likely to decrease beyond 12 oz., especially with higher MeHg fish.

The size of a beneficial effect is dependent on amount of MeHg in the fish.

Low MeHg fish produce greater benefits than high MeHg fish.

Higher MeHg fish can attenuate the benefit and, in some cases produce a net adverse effect, especially at higher levels of consumption. http://www.fda.gov/Food/FoodborneIllnessContaminants/Metals/ucm393211.htm

Figure D-4: COMPARISON OF NET EFFECTS FOR IQ FROM SALMON WITH TWO DIFFERENT DOSE METRICS FOR NUTRITIONAL BENEFITS

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Figure D-5: COMPARISON OF NET EFFECTS FOR IQ FROM CANNED LIGHT TUNA WITH TWO DIFFERENT DOSE METRICS FOR NUTRITIIONAL BENEFITS

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Figure D-6: COMPARISON OF NET EFFECTS FOR IQ FROM CANNED ALBACORE TUNA WITH TWO DIFFERENT DOSE METRICS FOR NUTRITIONAL BENEFITS

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Figure D-7: COMPARISON OF NET EFFECTS FOR IQ FROM SHARK WITH TWO DIFFERENT DOSE METRICS FOR NUTRITIONAL BENEFITS

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Fish: What Pregnant Women and Parents Should KnowDraft Updated Advice by FDA and EPAJune 2014 http://www.fda.gov/Food/FoodborneIllnessContaminants/Metals/ucm393070.htm

Key Message

Eat 8 to 12 ounces of a variety of fish* each week from choices that are lower in mercury. The nutritional value of fish is important during growth and development before birth, in early infancy for breastfed infants, and in childhood. 

What to do

1. Eat 8-12 ounces of a variety of fish a week.

That’s 2 or 3 servings of fish a week.

For young children, give them 2 or 3 servings of fish a week with the portion right for the child’s age and calorie needs.

2. Choose fish lower in mercury.

Many of the most commonly eaten fish are lower in mercury.

These include salmon, shrimp, pollock, tuna (light canned), tilapia, catfish, and cod.

3. Avoid 4 types of fish: tilefish from the Gulf of Mexico, shark, swordfish, and king mackerel.

These 4 types of fish are highest in mercury.

Limit white (albacore) tuna to 6 ounces a week.

4. When eating fish you or others have caught from streams, rivers, and lakes, pay attention to fish advisories on those waterbodies.

If advice isn’t available, adults should limit such fish to 6 ounces a week and young children to 1 to 3 ounces a week and not eat other fish that week.

Why this advice is important

Fish contains important nutrients for developing fetuses, infants who are breastfed, and young children. Fish provides health benefits for the general public. Many people do not currently eat the recommended amount of fish.

http://www.fda.gov/Food/FoodborneIllnessContaminants/Metals/ucm393070.htm

Conclusions

Effective food safety efforts for chemical contaminants require a multi-dimensional and disciplinary approach, involving surveillance and targeted monitoring and toxicological and epidemiological studies.

While the US food supply can be regional in nature depending on the time of year, it has become a year round global issue and therefore requires a global perspective.

Proactive and constructive collaborative efforts between local and national environmental and public health agencies, as well as international collaborative efforts between national, regional and international health organizations are required for an effective food safety program for chemical contaminants.