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Safety & Health

Exposure Scoring IV: Overview

Exposure Scoring IV: Overview

Barry Hooberman, MPH, Ph.D.
  Center for Veterinary Medicine/FDA

     AFSS Public Meeting
     May 22, 2007 

Exposure Scoring IV: Overview - Slide 1

Slide 2

Roadmap

 

Cont. A 

Cont. B 

Cont. C 

 Ei

Ingredient 1

Ingredient 2 

Ingredient 3 

 

Mill: Mix, Heat, etc. 

 

 MF

 

Finished Feed 

 

 Ef=Ei x MF

 

Animals 

 

 EA

 

 

Humans 

EH
Exposure Scoring IV: Overview - Slide 2

Slide 3

Roadmap – Expanded View

 

Mill: Mix, Heat, etc.
 
Mill: Mix, Heat, etc.
Mill: Mix, Heat, etc.
Mill: Mix, Heat, etc.
Mill: Mix, Heat, etc.

 

 

 

Finished Feed

 

 
     
 
Further Processing
 
Animal Diet
    
 Transport, Storage

 

Animals 
    

 

Humans
Exposure Scoring IV: Overview - Slide 3

Slide 4

Mathematically Speaking . . .

  • Level of contaminant in each feed ingredient
    • Ei x MF = Ef
  • Level of contaminant in final feed mix
    • Sum of (Ef x % ingredient in diet) for each ingredient in diet
  • Level of contaminant in final feed formulation
    • Adjustment for post-mixing processing (e.g., pelleting)
Exposure Scoring IV: Overview - Slide 4

Slide 5

Example – Dioxins (Step 1)

Level of contaminant in each feed ingredient:

Swine Diet Ingredients

Dioxins, ppt TEQ

EOW
(PES)

Adjusted mean

50%
0.0091

No
PES
necessary

0.0091


100%
0.0167

No
PES
necessary

0.0167


100%
0.58

No
PES
necessary

0.58

100%
0.338

No Effect

0.338

86%
0.02


0-10%

0.02

100%
0.3379
 

No Effect

0.3379

50%
0.0091

 50-70%

0.0146

Exposure Scoring IV: Overview - Slide 5

Slide 6

Example – Dioxins (Step 2)

  • Level of contaminant in final feed mix
    • Level of contaminant in each feed ingredient
    • Amount of each feed ingredient in final feed mix
    • Sum contaminant levels
Exposure Scoring IV: Overview - Slide 6

Slide 7

Swine Diet Composition
 

 

IngredientStarterGrowerFinisher
Corn51.8063.3579.18 
Soybean Meal, 46.5%27.95 28.018.83
Select Menhaden Fish Meal2.25    
Spary-dried blood cells0.85  
Spary-dried whey10.00    
Choice white grease  3.00  
Monocalcium Phosphate, 21% P 0.80   
Limestone0.800.25 0.83 
Salt 0.30 0.35 0.30 
Zinc Oxide 0.25  
Vitamins/trace minerals/phytase/amino acids 2.00  0.90 0.37
Fat 5.17 
Deflourinated Phosphate 1.92 
Copper Sulfate 0.05   
DDGs   10.00 
Dicalcium Phosphate   0.49
Exposure Scoring IV: Overview - Slide 7

Slide 8

Example – Dioxins (Step 2)

  • For “Finisher” diet
    • Corn contains 0.0091 ppt dioxins
    • Corn composes 79.18 % of diet
      (0.0091 ng dioxins/kg corn) x (0.7918 kg corn/kg feed)
       = 0.0072 ng dioxins/kg feed
    • Similar calculations for other feed components
    • Total dioxins in Finisher diet = 0.010 ng/kg feed 
Exposure Scoring IV: Overview - Slide 8

Slide 9

Example – Dioxins (Step 3)

  • Estimated levels of dioxins in final feed formulations:
    • Starter:  0.037 ng dioxins/kg feed
    • Grower:  0.028 ng dioxins/kg feed
    • Finisher:  0.010 ng dioxins/kg feed
    • Assuming no effect of pelleting, storage, or transport on dioxin levels in feed 
Exposure Scoring IV: Overview - Slide 9

Slide 10

Roadmap – Expanded View

 

Mill: Mix, Heat, etc.
 
Mill: Mix, Heat, etc.
Mill: Mix, Heat, etc.
Mill: Mix, Heat, etc.
Mill: Mix, Heat, etc.

 

 

 

Finished Feed

 

 
     
 
Further Processing
 
Animal Diet
    
 Transport, Storage

 

Animals 
    

 

Humans
Exposure Scoring IV: Overview - Slide 10

Slide 11

Exposures to Animals

  • Moving from contaminants in feed to animal exposures
    • Estimating daily exposures
      • Contaminant in feed (ng/kg) x feed consumed (kg/day) = ng Contaminant/day
    • Estimating lifetime exposures
      • For each stage:  ng Contaminant/day x number of days in diet stage = ng Contaminant/kg bw
      • For lifetime: add total contaminant consumed for all three stages
Exposure Scoring IV: Overview - Slide 11

Slide 12

Consumption Assumptions

 

Starter DietGrower DietFinisher Diet

3 - 8 wks

8 - 15 wks

15 - 24+ wks

10 - 50 lb

50 - 130 lb

130 - 250 lb

0.5 kg intake  

1.85 kg intake  

3.05 kg intake 

Exposure Scoring IV: Overview - Slide 12

Slide 13

Example – Dioxins (Step 4)

  • For swine Finisher diet:
    • Contaminant level:  0.010 ng dioxins/kg feed
    • Feed consumed:  3.05 kg/day
    • Length of time diet consumed: 70 days
       0.010 ng/kg x 3.05 kg/day x 70 days
      = 2.135 ng dioxins
  • Total dioxins consumer over swine lifetime
    • For Starter Diet: 0.65 ng
    • For Grower Diet: 1.8 ng
    • Total:  4.6 ng
Exposure Scoring IV: Overview - Slide 13

Slide 14

Exposures to Animals - Caveats

  • Assumptions/Factors
    • Biological half-life
      • Metabolism, elimination, excretion
    • Species differences
    • Worst-case scenarios
  • Remember – Goal is not estimating individual risks from contaminants
  • Transparency
    • Assumptions/factors are being tracked
Exposure Scoring IV: Overview - Slide 14

Slide 15

Exposures to Animals

  • What about microbiological contaminants?
    • Different type of dataset
      • Limited data – only detectable/non-detectable
      • Almost no data on levels of contaminants
    • High level of uncertainty on the relationship between presence of microbial contaminants and animal disease
Exposure Scoring IV: Overview - Slide 15

Slide 16

Roadmap – Expanded View

 

Mill: Mix, Heat, etc.
 
Mill: Mix, Heat, etc.
Mill: Mix, Heat, etc.
Mill: Mix, Heat, etc.
Mill: Mix, Heat, etc.

 

 

 

Finished Feed

 

 
     
 
Further Processing
 
Animal Diet
    
 Transport, Storage

 

Animals 
    

 

Humans
Exposure Scoring IV: Overview - Slide 16

Slide 17

Exposures to Humans

  • Human exposures via consumption of animal food products
  • Estimated exposures based on:
    • Chemical Contaminants
      • Residues in animals
    • Microbiological Contaminants
      • High level of uncertainty on the relationship between presence of microbial contaminants in animal feed and human disease
         
Exposure Scoring IV: Overview - Slide 17

Slide 18

Exposures to Humans

  • Chemical Contaminants
    • Estimating residues in edible products
      • Potential to bioaccumulate
        • Physico-chemical properties of contaminant
      • Biological half-life
        • Biological fate of contaminant in food animal
        • Metabolism, elimination, excretion
Exposure Scoring IV: Overview - Slide 18

Slide 19

Example – Dioxins

  • What are the concentration of dioxins in edible meat products from swine?
    • Dioxins are extremely fat soluble chemicals
    • Biological half-life approximately 100-200 days
    • Swine are generally marketed at approximately 160 days
    • Assumption: a worst-case scenario is 90% absorption with little elimination or excretion
    • Assumption: most of dioxins are in animal fat 
Exposure Scoring IV: Overview - Slide 19

Slide 20

Consumption Assumptions

Human Consumption Values for Edible Products

 

Edible Product  Grams Consumed/day
Muscle     300
Liver    100
Kidney    50
Fat    50
Milk    1500 mL
Eggs 100 
Exposure Scoring IV: Overview - Slide 20

Slide 21

Example – Dioxins

  • For swine contaminated with dioxin residues
    • Concentration of dioxins in fat (ng dioxins/kg fat)
    • Human adult dietary consumption (50g fat/day)
    • Estimate dioxin exposure (ng dioxins/day)
  • Many variables!!
    • Feed variables
    • Animal variables
    • Human variables 
Exposure Scoring IV: Overview - Slide 21

Slide 22

Validation

  • A Necessary Exercise!
    • Available data from complete feeds
    • Data mining FSIS data for residues in animal-produced food
    • Collect additional data
Exposure Scoring IV: Overview - Slide 22

Slide 23

Goals for Today

  • Concepts
    • Hazard Ranking vs. Risk Ranking
      • The difference is exposure
    • Types of data available to CVM
      • Chemical contaminants
      • Microbial contaminants
    • How data can be assembled to estimate exposure 
Exposure Scoring IV: Overview - Slide 23

Slide 24

Next Steps

  • Hazard Scoring
  • Exposure Scoring
    • Continue to collect information
      • Chemical contaminants
      • Microbiological contaminants
    • Refine scoring to reflect animal species
  • Estimating relative risks
    • Comparing chemical vs. microbiological risks?!? 
Exposure Scoring IV: Overview - Slide 24

Slide 25

The Team

AFSS Chair – George Graber
 

 

  • AFSS Risk
    • Subgroup:
    • Dolores Beblo
    • Karen Ekelman
    • Barry Hooberman
    • Shannon Jordre
    • Ibrahim Kamara
    • Al Montgomery
    • Phares Okelo
    • And a special thanks to Zoe Gill 
  • Experts and Number Crunchers:
    • Linda Benjamin
    • Henry Ekperigin
    • Michael Henry
    • Gil Kaplan, contractor
    • Mark Kerr, ORA
    • Randall Lovell
    • Jenny Murphy
    • Terry Proescholdt
    • Tim Schell
Exposure Scoring IV: Overview - Slide 25