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PART 1: Identification and Characterization of Chemical and Biological Hazards.

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Title: PART 1: Identification and Characterization of Chemical and Biological Hazards.


1
UNIT 3 KEY STAGES IN THE PROCESS OF RISK
ASSESSMENT
  • PART 1 Identification and Characterization of
    Chemical and Biological Hazards.

Christine CEZARD (Unit co-ordinator) Anabel
VITAS Kofi Aidoo IUT A USTL Lille France
University of Navarra Pamplona
Spain Glasgow Caledonian University
2
RISK ASSESSEMENT
_____________________________________________
Introduction
Identification and quantification of the risk
resulting from a specific use or occurrence of a
chemical, physical or microbiological agent,
taking into account possible harmful effects on
individual people or society of using the
agent in the amount and manner proposed and all
the possible routes of exposure
SCIENTIFIC PROCESS
3
THE RISK ASSESSEMENT PROCESS
_____________________________________________
Introduction
  • 1. Hazard identification
  • 2. Hazard characterization
  • 3. Exposure assessment
  • 4. Risk characterization

4
STEP 1. HAZARD IDENTIFICATION
______________________________________Hazard
identification
HAZARD a biological, chemical or physical agent
with the potential to cause an adverse health
effect (CODEX)
CHEMICAL RISK ASSESSMENT (CRA) Emphasis is
given to the adverse effects
The aim is to evaluate whether the chemical has
the potential to cause adverse effects in humans
based upon review of all available data on
toxicity and the biological mechanism that leads
to toxicity
5
______________________________________Hazard
identification
CHEMICAL HAZARD IDENTIFICATION
Determination of substances of concern,
their adverse effects, target populations and
conditions of exposure, taking into account
toxicity data and knowledge of effects on human
health, other organisms and their environment
(IUPAC)
STEP 1
6
______________________________________Hazard
identification
WHEN chemical hazards arise in the food supply?
  • Before the raw material enters the food
    processing
  • During the storage of raw materials
  • During the food processing
  • During the packaging
  • During the storage of the end-product
  • During the cooking at home
  • During its eating

STEP 1
7
______________________________________Hazard
identification
WHICH chemical hazards ?
  • Industrial and environmental contaminants
  • Biologically derived contaminants
  • Contaminants produced during processing
  • Improperly used agrochemicals
  • Improperly used additives

STEP 1
8
______________________________________Hazard
identification
STEP 1
Source ILSI Europe. Diane Benford.
http//europe.ilsi.org/file/ILSIcmRA.pdf
9
______________________________________Hazard
identification
STEP 1
Source ILSI Europe. Diane Benford.
http//europe.ilsi.org/file/ILSIcmRA.pdf
10
______________________________________Hazard
identification
STEP 1
Source ILSI Europe. Diane Benford.
http//europe.ilsi.org/file/ILSIcmRA.pdf
11
______________________________________Hazard
identification
DATA USED? RESULTS FROM
  • Human studies (epidemiology, case reports or
    volunteer studies)
  • Toxicity studies conducted in laboratory animals
  • Alternative approaches, including use of in vitro
    models such as cells cultures or tissue slices,
    and comparisons with structurally-related
    chemical substances

ADVANTAGES AND DISADVANTAGES
STEP 1
Often, the information provided by different
studies is complementary
12
______________________________________Hazard
identification
CHEMICAL HAZARD IDENTIFICATION
Human studies Criteria which provide evidence of
a causal link between exposure and effect in
epidemiology studies. Hill, 1965
1. The strength of association (difference
between exposed and unexposed populations) 2. The
consistency of the association (studies conducted
by different investigators in different places,
circumstances, times) 3. The temporal
relationship (exposure must precede the
disease) 4. The biological gradient of the
association (higher risk of disease with higher
level of exposure) 5. The specificity of the
association (disease rare in absence of
the exposure) 6. Biological plausibility
(supported by results in experimental animals)
STEP 1
13
______________________________________Hazard
identification
CHEMICAL HAZARD IDENTIFICATION
Studies in laboratory animals Observations and
measurements of potential toxic effects.
1. Functional changes (reduced weight gain) 2.
Morphological changes (organ enlargement,
histopathological lesions ) 3. Mutagenicity
(heritable changes in DNA, genes and
chromosom.) 4. Carcinogenicity (cancer) 5.
Immunotoxicity (allergy, depression of the immune
system) 6. Neurotoxicity (behaviour changes,
tinnitis, deafness) 7. Reproductive effects
(impaired fertility, abortion, teratogenicity, oth
er development effects)
STEP 1
14
______________________________________Hazard
identification
CHEMICAL HAZARD IDENTIFICATION
Alternative techniques to minimise the use and
suffering of laboratory animals. They should
finally combined with animal experimentation..
1. In vitro approaches 2. Computer modelling
STEP 1
15
______________________________________Hazard
identification
EXAMPLE CHEMICAL HAZARD IDENTIFICATION
Observations - They have been shown to induce
liver cancer in most animal species that have
been studied - Epidemiological studies show a
correlation between exposure of aflatoxin B1 and
increased incidence of liver - Aflatoxins are
metabolised in humans and test animal species to
produce an intermediate reactive which is
considered responsible changes in genetic
material Hazard identification - Aflatoxins are
considered to cause liver cancer in humans,
based upon the weight of evidence
AFLATOXINS
STEP 1
Source ILSI Europe. Diane Benford.
http//europe.ilsi.org/file/ILSIcmRA.pdf
16
STEP 2. HAZARD CHARACTERIZATION
____________________________________Hazard
characterization
Qualitative and/or quantitative evaluation of
the nature of the adverse health effects
associated with biological, chemical and physical
agents
For chemical agents a dose-response assessment
should be performed. For biological agents a
dose-response assessment should be performed if
the data are obtainable.
17
____________________________________Hazard
characterization
To estimate the nature, severity and duration of
the adverse effects resulting from ingestion of
the agent in question it is necessary to know
1. The fate and distribution of the chemical
agent in the body 2. The action of the chemical
agent on tissues or functions in the body
STEP 2
18
____________________________________Hazard
characterization
CHEMICAL HAZARD CHARACTERIZATION
Hazard charazterization is closely linked to
hazard identification
  • Hazard identification revealed the type(s) of
    toxicity associated with a particular substance
  • Hazard characterization the focus is on the
    relationship between dose and response that is
    revealed in these studies and subsequent
    estimation of dose levels that may cause that
    response in humans

STEP 2
19
____________________________________Hazard
characterization
DOSE RESPONSE
  • NOAEL the highest dose level without adverse
    effect in the toxicity study that demonstrated
    the relevant critical effect(s).
  • LOAEL the lowest observed adverse effect level
    (in case that effects were seen at all dose level
    used in the key toxicity study).

STEP 2
20
____________________________________Hazard
characterization
Typical dose-response graphic
STEP 2
21
____________________________________Hazard
characterization
Hazard characterization based in laboratory
animal toxicity studies which identify the
critical effect
THE PESTICIDE
Toxicity studies in experimental animals -
Establish the highest dose level without effect
(the NOAEL) in the study that identifies the
critical effect Toxicokinetic studies - Data on
absorption, distribution and excretion of major
metabolites. Effects of dose level and duration
on the metabolism - Comparative studies in human
volunteers to support extrapolation of animal
toxicity data Hazard characterization -
Establish acceptable daily intake (ADI)
NOAEL/safety factor
Source ILSI Europe. Diane Benford.
http//europe.ilsi.org/file/ILSIcmRA.pdf
22
____________________________________Hazard
characterization
Hazard characterization based in epidemiological
studies if they include adequate exposure data
AFLATOXINS
- Epidemiological data on the dose-response
relationship are influenced by concurrent
infection with hepatitis B - Data indicate two
separate potencies for aflatoxins (in populations
with common hepatitis infection and in
populations in which chronic hepatitis infection
is rare) - The shape of the dose response curve
is unknown, which increases uncertainty related
to application of mathematical models for
extrapolation from animals to man, and from high
dose to low dose
Source ILSI Europe. Diane Benford.
http//europe.ilsi.org/file/ILSIcmRA.pdf
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