Toxicology

1. APPLICATION OFAPPLICATION OF
TOXICOLOGY :TOXICOLOGY :
RISK ASSESSMENTRISK ASSESSMENT
Fadzil B. Othman
Food Safety and Quality Division,
Ministry of Health, Malaysia
3 June 2010.

2. Toxicology;
“ No chemical agent is
entirely safe and no agent is
entirely harmful”

3. "All substances are poisons; there is
none which is not a poison. The right
dose differentiates a poison and a
remedy.“
(Paracelsus, 1500 AD)

4. Risk Assessment: ElementsRisk Assessment: Elements
1. Hazard identification
Identification of biological,
chemical, or physical agent
2. Hazard characterisation
Evaluation of adverse health effect
3. Dietary exposure
Estimate of intake
4. Risk characterisation
Probability of occurrence and severity of
potential adverse health effect

5. Risk AssessmentRisk Assessment
 What is the nature and magnitude of
the health risk associated with a
particular chemical?
 How should the risk be managed and communicated to those affected?
Risk Management

6. Risk AssessmentRisk Assessment
Risk assessment is a scientifically
based process consisting of 4 steps:
◦ Hazard identification
◦ Hazard characterization
◦ Exposure assessment
◦ Risk characterization
Risk Management
Risk Communication

7. Hazard Identification;Hazard Identification;
Consisting of the determination of
substances of concern, the adverse effects
they may have inherently on target
systems under certain conditions of
exposure, taking into account toxicity data
and knowledge of effects on human health.

8. Question
Is there potential to cause health problems in
humans?
(i) food (ii) food ingredient (iii) contaminant or
(iv) substance added to food
Evidence
1. Human evidence (epidemiological, poisoning
cases)
2. Animal and human in vivo studies
3. Comparative analysis
Hazard Identification

9. Hazard identification
Understanding what the concerns about the
chemical are:
Is it likely to cause health problems?
e.g. acute toxicity, cancer, kidney damage
Hazard characterisation (dose-response
assessment)
Understanding the dose-response relationship:
- is it a problem at low doses?
- is it a problem at high doses only?

10.  Animal toxicity studies
(rats, mice dogs)
 Human data
(epidemiological data, human toleration studies,
Controlled clinical exposures (e.g. for drugs)
Also use
◦ In vitro studies
(Structure-activity relationships)
 Data from non-food use
(occupational or accidental exposure)
Data Sources for HazardData Sources for Hazard
IdentificationIdentification

11. Chemical Risk Factors in FoodChemical Risk Factors in Food
 Agricultural chemical
residues
 Veterinary chemical
residues
 Chemicals formed during
cooking and processing
 Environmental
contaminants
 Food additives
 Food processing aids
 Packaging chemicals
 Plant toxins
 Marine toxins
 Mycotoxins
 Radionuclides
 Nutrients
 Novel food ingredients

12. Toxicity EndpointsToxicity Endpoints
 Acute toxicity – eg, nausea, neurotoxicity
 Organ toxicity – eg, hepatotoxicity, kidney
damage
 Genotoxicity – eg, gene mutation,
chromosomal damage
 Carcinogenicity
 Neurotoxicity
 Teratogenicity (birth defects)

Reproductive toxicity

13. Which is the critical endpoint?Which is the critical endpoint?
 Enzyme induction
 Bodyweight gain decrease
 Elevated blood parameters
 Increase in urinary protein
 Liver foci
 Birth defects
 Cancer

14. Interpreting toxicity studies (1)Interpreting toxicity studies (1)
Highest dose should not exceed >5% of
total diet→nutritional imbalances
Do not want severe/extreme toxic effects
that compromise the duration or results of
the study →uncertainties
Controls-concurrent, negative/positive,
historical, vehicle

15. Interpreting toxicity studies (2)Interpreting toxicity studies (2)
Validity of older studies
Species-specific effects
Statistical versus biological significance
Limit dosing versus three doses
Weight of evidence-judgement, adequacy,
validity and appropriateness of data base.

16. Interpreting toxicity studies (3)
Is the effect a physiological or toxicological one?
• Physiology
– Variation within limits of normal function (e.g.
variation in liver enzymes following a meal).
• Toxicology
– Reversible/irreversible; Injurious and therefore
adverse and harmful

17. What can studies tell us?What can studies tell us?
That the chemical can be a hazard - it
has a particular adverse effect at a
particular dose
Lowest dose (threshold)
No effect or lowest effect level
Is there a dose-response effect?

18. Hazard identification - was is the adverse
effect/s caused by a chemical? (e.g. liver
changes versus neurotoxicity)
Toxicological endpoints, target organs,
threshold, NOEL, LOEL

19. All substances are hazardous under
certain conditions of exposure (we are
looking at the oral route for food)
Sometimes need only small amounts
for it to be a hazard.
Toxicity is a function of amount
received - dose is very important

20. Biological extrapolation, dose-
response and dose-effect
relationships, and their respective
attendant uncertainties
Hazard Characterisation
Evaluation of adverse health effect

21. hazard assessment: process
designed to determine factors
contributing to the possible
adverse effects of a substance
to which a human population
could be exposed. The process
includes three steps:
hazard identification,
hazard characterization, and
hazard evaluation (see Fig. 1).
Note: Factors may include
mechanisms of toxicity, dose-
effect and dose-response
relationships, variations in
target susceptibility,

22. Hazard Assessment
Epidemiological data
- less precise
- highly relevant
Animal toxicity data
- more precise
- less relevant
OUTCOMES
• Some understanding of kinetic and metabolism
• Identify target organs
• Possible mechanism of action
• Dose-response relationship
• Evidence of a threshold/NOEL
NOEL: No Observed Effect Level

23. Hazard Characterisation OutputsHazard Characterisation Outputs
1. Shape of the dose-response curve
2. Identification of thresholds of toxicity
3. Determine appropriate safety factors
4. Establish reference health standards, if
possible

24.  Dose-response relationship
Dose
Severity
of response
X
X
X
X
•Dose-response-relationship between magnitude of dose and incidence or severity
of adverse effect

25. What is a Response ?
Change from normal state – Response
(symptoms) could be on the molecular,
cellular, organ or organism.
Local Vs Systemic
Immediate Vs Delayed
Graded Vs Quantal (degrees of the
same damage Vs all or none)

26. Dose
Severity
of response
X
X
X
X
NOEL
LOEL
Threshold - lowest dose which causes an effect, below this dose, no toxicity
is observed
NOEL – highest dose employed at which no effect was observed (derived
experimentally)
LOEL - lowest dose at which there was an observed effect (derived
experimentally)
26

27. Exposure
Food 1 Food 2 Food 3 All foods
ADI (food additive) or TDI (contaminant)
Natural level in foo
Qualitative Estimate of Risk (1)
Food 4

28. Qualitative estimate of risk (2)
Use of Benchmark Dose modeling
%
Response
Dose
X
X
X
X
X
95% confidence
levels
Use mathematic models to establish a dose-response curve
which will predict (with 95% confidence) the dose which
will give a particular % response in the population.
5% response
BMDL

29. Exposure Assessment
Dietary intake for mean and 95th
% ile consumers
Dietary intake for different age groups
Dietary intake for vulnerable population groups
Short-term exposure (one meal – one day)
Medium-term exposure (days – months)
Long-term exposure (years – lifetime)

30. Exposure AssessmentExposure Assessment
An exposure assessment for a particular
chemical is based on:
1. The amount of the chemical in food
2. The level of food consumption

31. Risk Characterisation
Integration of the information from exposure
assessment and hazard characterisation into
advice suitable for use in risk management
Hazard
characterisation
Exposure assessment
Advice to risk managers
+

32. Risk Characterisation OutcomesRisk Characterisation Outcomes
 Estimation of risk
 Identification of at-risk (sensitive)
populations
 Uncertainties in the assessment

33. The Nature of Advice to Risk
Managers
• Quantitative advice
- level of risk at given exposure (difficult to obtain)
- ADI/ TWI (most common)
- margin of exposure (useful in some cases)
• Qualitative advice
- conditional approval (eg, only particular production method
allowed; only certain uses allowed)
- minimize exposure (as low as reasonable achievable)
- avoid intake by certain groups

34. Defining the Risk
No appreciable risk
Very low risk
As safe as the traditional counterpart
Large margin of safety / exposure
No safety concerns
under the conditions of
use
Prohibited from
use in food
No additional risk

35. Risk Characterisation Outcome:Risk Characterisation Outcome:
Qualitative advice regarding riskQualitative advice regarding risk
1. Levels in food should be as low as reasonably
achievable (unavoidable contaminant)
2. Avoidance of foods from certain sources (highly
contaminated soils)
3. Avoidance of certain ingredients from use in food
altogether (toxic plants)

36. Risk Characterisation Outcome:Risk Characterisation Outcome:
Qualitative advice regarding riskQualitative advice regarding risk
4. Avoidance of certain process (eg, ethylene
oxide sterilization of spices)
5. Modification of production process (soy sauce
production)
6. Reduction of intake of certain foods (eg, lupin
seeds)

37. Reference Health StandardsReference Health Standards
 Acceptable daily intake (ADI)
- food additives, pesticides
 Tolerable daily intake (TDI)
- contaminants, natural toxins
 Upper safe level (UL)
- nutrients

38. Chemicals with an ADI or TDIChemicals with an ADI or TDI
A comparison can be made between the ADI (or TDI) and
the anticipated (or known) level of exposure from all foods
for each population group.
exposure
ADI (or TDI)
Age groups

39. Chemicals without an ADI or TDIChemicals without an ADI or TDI
Margin of exposure: Ratio between either
the LOEL or BMDL and the estimated
human exposure.
Exposure
Toxic effect level or LOEL or BMDL
Age groups
Margin of
exposure

40. Compound that are both GenotoxicCompound that are both Genotoxic
and Carcinogencic;and Carcinogencic;
European Food Safety Authority – Largo N. Palli 5/a – I-
43100 Parma – Italy
Telephone: +39 0521 036 111- Fax: +39 0521 036 110
European Food Safety Authority
3rd November 2005
EXPLANATORY NOTE
of the Opinion on a Harmonised Approach for the Risk Assessment of
Substances which are both Genotoxic and Carcinogenic
The Scientific Committee (SC) of the European Food Safety
Authority recommends a harmonised concept using the “margin of
exposure” (MOE) approach, a methodology that does enable the
comparison of the risks posed by different genotoxic and
carcinogenic substances. Differences in potency of the substances
concerned and consumption patterns in the population are taken
into account when applying the MOE approach.

42. Chemicals with Human Toxicity DataChemicals with Human Toxicity Data
• Eg: mercury, cadmium, aflatoxin, lead
- Identify toxic endpoint for humans
- Safety factor for inter-individual variation only (no
inter-species issue)
- May be possible to relate exposure to actual risk in
the population

43. AflatoxinAflatoxin
• Epidemiological data linking aflatoxin with liver cancer
• Genotoxic potential
• Difficult to identify a threshold – likely to be very low.
• Human data sufficient to estimate risk (cancer
incidence) at different levels of exposure
• Exposure ‘as low as reasonably achievable’

44. AflatoxinAflatoxin
• Several epidemiological studies providing dose-
response data on human liver carcinogenicity
• Possible to relate the exposure level to the
cancer incidence in the population
• Potency estimates range from 0.002 to 0.036
cases of liver cancer per year per 100,000
individuals assuming an exposure of 1 ng/kg per
day

45. NeotameNeotame
(new intense sweetener)(new intense sweetener)
 ADI: 2 mg/kg bw per day
 Wide proposed use in food
 Total estimated dietary exposure: less than ADI
 Use level in food: GMP in all foods

46. Neotame ExposureNeotame Exposure
The total anticipated level of dietary
exposure to neotame from all foods is
below the ADI
Neotame
exposure
from all
foods
ADI
Age groups

47. Exceeding the ADI for a Short Period forExceeding the ADI for a Short Period for
a Food Additivea Food Additive
• ADI for almost all food additives is derived from long-term
animal studies
• ADI is based on a NOEL from animal studies using a safety
factor (usually 100)
• The NOEL is based on the most sensitive adverse effect (eg,
enzyme induction, bodyweight changes, clinical pathology
parameters)
Brief exposure over the ADI for most
food additives is not a health concern

48. Exceeding the ADI for a Short Period forExceeding the ADI for a Short Period for
PesticidesPesticides
• ADI for most pesticides is derived from long-term
animal studies; but some are based on shorter-term
studies
• NOELs may be based on more critical end-points
(eg, teratogenicity)
Brief exposure over the ADI probably not
significant for most pesticides, but the ARfD
should not be exceeded

49. Environmental Contaminants and NaturalEnvironmental Contaminants and Natural
ToxinsToxins
More complex risk characterisation:
• Toxicity data is more limited – may not be
possible to set a TDI
• Some contaminants are carcinogenic –
questionable safety threshold
• Safety factors often lower than for food
additives
• More likely to be sensitive sub-populations

50. Short Term Exposure versus LifetimeShort Term Exposure versus Lifetime
Exposure: Dioxin / CadmiumExposure: Dioxin / Cadmium
Decades of low level cadmium or dioxin exposure is
required before toxicity is evident
• Short term exposure over the TDI is not a
concern
• Cumulative body burden is the critical effect

51. Acrylamide riskAcrylamide risk
assessmentassessment
JECFA (2005) risk characterization:
i) Morphological changes in nerves
 NOEL = 0.2 mg/kg bw per day
ii) Reproductive, developmental, and other non-neoplastic
effects
o NOEL was 2 mg/kg bw per day.
(iii) Cancer (Mammary gland tumors in rats)
 BMDL = 0.3 mg/kg bw per day;

52. JECFA (2006) EvaluationJECFA (2006) Evaluation
o Cancer (Mammary gland tumors in rats)
BMDL = 0.3 mg/kg bw per day;
MOE - mean intake = 300 and high intake = 75
o Committee considered MOE to be low for
genotoxic and carcinogenic compound.
Also proposed by the European Food Safety
Authority (EFSA).

53. Calculation of acrylamide IntakeCalculation of acrylamide Intake
Data on survey in Penang (2002) and limited data
(snack food) in Serdang (2008) was used for dietary
exposure.
Food Consumption Statistic of Malaysia 2002/2003
for adult population (18-59 years old), based on FFQ,
was used as the food consumption data.
A semi-quantifiable serving size as reference (food
album) was used as the estimated consumption of
each food (g/day).

54. Dietary Exposure
Assessment Methodology
Dietary
Exposure =
Food
Consumption
x
Acrylamide
Concentratio
n in foodΣ
Summed for all foods and
adjusted for body weight.

55. Table 1 : Acrylamide in Malaysian Food Tested in 2003.Table 1 : Acrylamide in Malaysian Food Tested in 2003.
Food Type
Number of sample
analyzed
Acrylamide (µg/kg)
Mean (UB) Range
Mee and pasta (fried, uncooked) 18 13.4 <10-72
Fried potato/French fries 8 117.4 10-551
Potato chip (fried) 8 479.5 <10-693
Nut (baked, boiled) 15 10.5 <10-17
Maruku (Fried) 6 104.5 25-212
Kuih assorted (fried, roasted, steamed, baked) 41 23.5 <10-123
Murtabak (baked flat pan) 5 45.2 <10-74
Bread (baked) 7 20.9 <10-39
Kuih traditional (baked) 10 29.7 <10-81
Pau (steamed) 6 35 <10-78
Chips and crackers (fried) 7 77.3 <10-426
Kek lapis (baked) 5 42.4 20-66
Piza (baked) 8 13.5 <10-28
Others (Chinese food) (fried) 3 39.7 <10-66

56. Table 2: Dietary exposure to acrylamide in Malaysia diet for 18-59 year olds with theTable 2: Dietary exposure to acrylamide in Malaysia diet for 18-59 year olds with the
average body weight 63 kg.average body weight 63 kg.
Food
Group
Mean Concentration
(µg/kg)
Food Consumption Estimated
Mean
Intake (µg/day)
Approximate
Percent
Contribution (%)Mean (g/day) 97.5%tile (g/day)
Potato chips 479.5 5.85 38.57 2.80 18
French fries 117.4 5.85 38.57 0.68 4
Maruku 104.5 5.85 38.57 0.61 4
Murtabak /roti canai 45.2 21.11 93 0.95 6
Layer Cake 42.4 4.19 21.71 0.17 1
Chinese Foods
(Hup tau Seow, Khung Tung, Yu
Teow )
39.7 66.56 250.74 2.64 17
Malaysian Traditional cakes 23.5 21.63 90 0.50 3
Buns and Breads 19 36.1 136 0.68 4
Pizza 12 3.35 15.4 0.04 0
Peanut and soya 10.5 56.9 324 0.59 4
Instant and wheat noodle 13.4 66.34 288 0.88 7
Banana chips (n=3) 759 5.85 38.57 4.44 30
Fish crackers 65 5.85 38.57 0.38 2
Tapioca chips, 10 5.85 38.57 0.05 0
TOTAL 14.53 100
Estimated exposure acrylamide
(mg/kg bw/day)
0.00023
Margin of Exposure (MOE)
1300

57. Risk Estimate
Total dietary exposure estimated from food
consumption:
i) Malaysia = 0.23 µg/day/ kg body weight.
ii) Sweden and Switzerland = 0.67 µg/kg bw/day
(a person of 60 kg body weight)
 In terms of risk of causing cancer, the MOE calculated
based on values BMDL10 of 0.3 mg/kg bw/day is 1300.
This is far below 10,000, indicating exposure to
acrylamide is of public health concern.

58. When is it necessary to review a
risk characterisation?
• New data on nature of the material in
food
• New data on hazard identification
• New data on exposure
• Increased or altered pattern of use

59. Is a detailed risk assessment
always necessary?
 Exposure may be extremely low (eg, <1 ppm)
 eg, flavours and food contact chemicals
 Toxicity data may never be ‘sufficient’
 eg, naturally-occuring toxins
 Hazard may be irrelevant to the exposed
individuals
 route of exposure, vehicle, lifestage