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Safety & Health

Challenges in Developing a Risk Ranking Model for Feed Contaminants

Challenges in Developing a Risk Ranking Model for Feed Contaminants

Dolores A. Beblo, Ph.D.
U.S. Food and Drug Administration

Prepared for presentation at CVM
Animal Feed Safety System (AFSS)
Rockville, MD Public Meeting

September 12, 2006
 

Challenges in Developing a Risk Ranking Model for Feed Contaminants - Slide 1

Slide 2

For improving public health, which feed hazards should receive the most surveillance or regulatory attention? 

Challenges in Developing a Risk Ranking Model for Feed Contaminants - Slide 2

Slide 3

Risk Ranking Tool

Framework for organizing information on feed contaminants, feed production, processing and consumption

Uses:

  • Compare and evaluate different exposure    
  • scenarios Identify what data gaps exist for estimating and optimizing mitigating interventions 
Challenges in Developing a Risk Ranking Model for Feed Contaminants - Slide 3

Slide 4

Risk Ranking Model Components

Hazard Identification

Hazard Characterization/
Health Consequence Scoring

Exposure Assessment

Relative
    Risk Ranking
 

Challenges in Developing a Risk Ranking Model for Feed Contaminants - Slide 4

Slide 5

Hazard Identification

Data Sources

Evidence of animal feed contamination

  • FDA Feed Contaminants Program investigational sample data
  • FDA surveys of feed ingredients and     feed
  • USDA Food Safety and Inspection Service (FSIS) National Residue Program (NRP) sampling for pesticides   and environmental contaminants where  investigation indicated a feed source 
Challenges in Developing a Risk Ranking Model for Feed Contaminants - Slide 5

Slide 6

Hazard Identification (cont.)

Data Sources

Evidence that contaminated animal feed results in animal health consequence

  • Infection outbreak and feed contamination incident reports 
Challenges in Developing a Risk Ranking Model for Feed Contaminants - Slide 6

Slide 7

Hazard Identification (cont.)

Evidence that contaminated animal feed results in human health consequence

Data Sources

  • Epidemiological studies of bovine spongiform encephalopathy (BSE)

Data Needs

  • Only limited data for Salmonella 
Challenges in Developing a Risk Ranking Model for Feed Contaminants - Slide 7

Slide 8

Hazard Characterization of Contaminant

Factors that influence the outcome of exposure to contaminant

  • Potency and severity (Health Consequence Scoring)
  • Contaminant physical and chemical properties
  • Strain virulence
  • Feed composition
  • Factors related to conditions of ingestion
  • Animal and human host factors
  • Sensitivities of populations 
Challenges in Developing a Risk Ranking Model for Feed Contaminants - Slide 8

Slide 9

Health Consequence Scoring

Probability of consequence from ingestion of a given amount of contaminant

  • Chemical hazards: various reported reference levels for acceptable exposure (NOAEL, RfD, ADI, AEL)
  • Microbial hazards: limited data; infective doses reported, but one unit might cause infection
     
Challenges in Developing a Risk Ranking Model for Feed Contaminants - Slide 9

Slide 10

Chemical vs. Microorganism Hazard Characterization

  • Different factors for  contaminant classes: chemical or biological
  • Relative weighting across and within class 
Challenges in Developing a Risk Ranking Model for Feed Contaminants - Slide 10

Slide 11

Animal and Human Host Factors

  • Age
  • Human immune status
  • Others beyond AFSS scope initially 
Challenges in Developing a Risk Ranking Model for Feed Contaminants - Slide 11

Slide 12

Hazard Characterization

Data Sources

  • Scientific literature
  • Battery of chemical toxicity studies

Data Needs

  • Limited pathogen dose-response data in animals and humans
  • Incomplete epidemiological information
  • Difficulty in extrapolating from animal data to humans or other animals
  • Lack of mechanistic models
Challenges in Developing a Risk Ranking Model for Feed Contaminants - Slide 12

Slide 13

Exposure Assessment

  1. What is the probability of consumption of contaminated feed?
  2. What are the likely numbers of  microorganisms or amounts of physical  or  chemical contaminants in the feed at  the time of consumption? 
Challenges in Developing a Risk Ranking Model for Feed Contaminants - Slide 13

Slide 14

Exposure Assessment

  • Levels in raw feed ingredients
  • Processing and production
  • Levels in feed
  • Distribution and storage
  • Feed handling practices
  • Feed consumption
  • Animal vs. human
     
Challenges in Developing a Risk Ranking Model for Feed Contaminants - Slide 14

Slide 15

Exposure Assessment

Data Sources

  • FDA Feed Contaminants Program  investigational  sampling – exposure estimate from residue  prevalence, reference level of detection, and  consumption survey data

Data Needs

  • FDA Feed Contaminants Program investigational sampling - No quantitative microorganism count data
  • Not all feed contaminants of concern are included in current sampling programs
  • Opportunities for industry contribution 
Challenges in Developing a Risk Ranking Model for Feed Contaminants - Slide 15

Slide 16

Model Development is an Iterative Process

Surveillance Data (Time N)

Surveillance Data (Time 2)
Scientific Literature &
Surveillance Data (Time 1)


        Model Iteration 1
        Model Iteration 2

        Model Iteration N

Challenges in Developing a Risk Ranking Model for Feed Contaminants - Slide 16

Slide 17

Model Quality/Adequacy

  • Are the essentials for safeguarding animal feed captured?
  • Too much or little detail?
  • Validity of assumptions?
  • Is data variability reflected?
  • How is uncertainty handled?
  • Transparent development process? 
Challenges in Developing a Risk Ranking Model for Feed Contaminants - Slide 17

Slide 18

Promoting and Protecting Public Health

Thanks for your attention 

Challenges in Developing a Risk Ranking Model for Feed Contaminants - Slide 18