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Toxicity Powered By Docstoc
					            Risk Communication

• Outrage may distract from hazard and may
distill key social values
• If hazard is low, communication should
decrease outrage by making risks voluntary,
familiar, fair, and by shared power in the
        Communication Principles

• Old style

– Science alone provides objective truths - ie
the proverbial “white paper”
– Science experts are only possible source
of risk evaluation
– Consuming public will listen to “truths” –
but they don’t
        Communication Principles

• New Paradigm

– Right of public to provide input on public
policy decisions
– Free flow of information (but don’t cry fire in
the wrong place)
– Be honest, frank and open
– Issue burnout - like this course
  Risks in Our Food Supply

The dose makes
the poison
     Risks in Our Food Supply

1. Natural Toxins

•   Natural =/= Safe
•   Potato has more than 250 neurotoxins
•   Raw soybeans – antitrypsin
•   Cassava – cyanide
•   Raw wheat flour - polyphenolics
       Risks in Our Food Supply

1. Natural Toxins

• Phenolic compounds – neurotoxins
• Cyanogenic toxins
• Mutagens
• Anti-nutritional factors
• Biogenic amines – Hypertension
• carcinogens

• Agaratine - DNA breaker -> cancer

• @ 1.2 mg/70 Kg person
• Detection limit +/- 5%
•Safe dose - 4 g mushrooms/day or one
100g meal per 3 months - risk 1 in one
• Cancer 1 in 4 of all deaths
•5000 new cases / million population per
            Food Additives

1- Artificial colors and preservatives
              Food Additives

2- Artificial sweeteners

• Cyclamates - OK in Canada and Europe
• Saccharin - banned but now allowed - rat
cancer label

saccharin warning statement
“Use of this product may be hazardous to your health.
This product contains saccharin which has been
determined to cause cancer in laboratory animals.”
              Food Additives

• Aspartame
- reported to be linked to brain tumors –

warning label
• 1980 FDA received 7232 adverse reaction
• 46% from diet soft drinks
•28 % complained of headaches
•11% dizziness
•10% mood change
•10 % diarrhea/vomiting
• 6% change in vision
            Food Additives

• Olestra

- 164 adverse reactions of 450,000 consumers of

- 345 adverse reactions consumers from
Pringles <0.05% as reported by Frito-Lay
             What is a safe food?

• One that does not exceed an acceptable
level of risk

(Nestle, M. 2003. Safe Food. Bacteria, Biotechnology and Bioterrorism)
How do you determine “an acceptable level of

      • Science
      • Opinions
      • Perception
      • Values
Food Safety- Contaminants and
            NFSC 351

    Toxicity and Classification of
          What is Toxicology?

• It is the toxin science or the science of
• Deals with foreign substances that are
apart from those necessary for the normal
metabolism of a living organism
           What is Toxicology?

• It is a multidisciplinary science with close
relationships with other sciences such as
pharmacology, biology, food, physiology,
               Modern Toxicology

• Mathieu Orfila was the establisher of modern

• He was the first person to find a systematic
relationship between the chemical and
biological effects of toxins
             Modern Toxicology

• Orfila discovered that toxins not only
accumulate in the stomach but are absorbed
by the GI tract and get to several organs

• The concept of an antidote for specific toxic
substances and the treatments for toxic
diseases were evolved
            Branches of Toxicology

Analytical Toxicology
• This is called chemical toxicology
• Deals with the isolations of toxins from the
biological material, definitions of toxins and
investigations of methods for analysis of toxic
            Branches of Toxicology

• The analysis in chemical laboratories of
food contaminants, food additives and some
natural toxicants of food are related to this
branch of toxicology
              Branches of Toxicology

  Biochemical Toxicology

• Examines the toxic substances in the living
organism at a molecular level

• It forms the basis of all other branches of
             Branches of Toxicology

Economic Toxicology
• Deals with the selective effects of chemical
substances on biological tissues
• It uses the knowledge of these effects to
develop drugs, food additives and pesticides
             Branches of Toxicology

Environmental Toxicology

• Deals with the toxicological events that occur
as a result of the exposure of human beings to
the chemical substances that pollute the
             Branches of Toxicology

• Clinical Toxicology

• It deals with the harmful effects of chemical
substances on humans and animals and
examines poisonings from the legal point of
               What is Toxicity?

“ The capacity of a substance to cause
adverse health effects (injury, hazards) on a
living organism”
                   Types of Toxicity

• Local Effects: Skin Irritation

• General Effects: Impaired coordination,
behavioral changes, organ structure
changes or death

• Toxicity of a chemical substance is related to
the amount, or dose taken into the organism
• Acc to Paracelsus “ All substances are
poisons; there is none which is not”
• The right dose differentiates a poison and a

• For practical and industrial purposes, the
toxicities of chemical substances are expressed
by using their LD50 values
• LD50 values the “median lethal dose”
• LD50 can be defined as the amount of toxin
necessary to kill 50% of experimental animals
                  Toxicity Rating Chart
Toxicity          Commonly       LD50 Single   Probable
Rating            Used term      Oral Dose     Lethal Dose
                                 Rats          for Man
1                 Extremely      <1mg/kg       A taste, 1
                  Toxic                        grain
2                 Highly Toxic   1-50mg/kg     1 teaspoon,
3                 Moderately     50-500mg/kg   1 ounce, 30g
4                 Slightly Toxic 0.5-5g/kg     1 cup, 250g

5                 Practically    5-15g/kg      1000g
6                 Relatively     >15g/kg       > 1000g
    Derelanko, 1995
          Approximate Acute LD50 of Selected
           Chemical Agents Found in Foods

   Chemical Agent              LD50 (mg/kg)
Sodium Chloride         4000

DDT                     100

Arsenic                 48

Botulinus toxin         0.00001

A toxic substance shows its harmful effect by
entering a reaction with the living organism
            Stages of Toxication
Exposure to the toxic substance, entrance of
 the toxic substance to the organism and its
   absorption through the cell membranes
  Distribution of the toxic substance in the
   living organism, its accumulation and
    Metabolism of the toxic substance
        Beginning of the toxic effects
              Excretion of the
             metabolites of toxic
Routine Toxicity Tests Commonly Required in
   Determining the Degree of Hazardous
           Compounds in Foods

1- Acute Toxicity: Single Dose
• Determines Nature of acute (overdose)
effects; target organs or systems and
median lethal dose (LD50)
  Routine Toxicity Tests Commonly Required in
     Determining the Degree of Hazardous
             Compounds in Foods

2- Subchronic Toxicity: 28-90 day repeat dose
studies usually in diet or drinking water
• Determines nature of toxicity; target organs
or systems
• Dose-response characteristics:
- No Observed Adverse effect Level (NOAEL)
- Maximum Tolerated Dose (MTD)
Routine Toxicity Tests Commonly Required in
   Determining the Degree of Hazardous
           Compounds in Foods

3- Chronic Toxicity: Long Term dietary
administration, e.g. 6 months to 2 years in rats
and mice

• Determines nature of chronic toxicity; target
organs or systems; cumulative effects
Routine Toxicity Tests Commonly Required in
   Determining the Degree of Hazardous
           Compounds in Foods

4- Reproductive Toxicity: Single or Multiple
dose studies during pregnancy

• Determines effects on fertility (male and
female); fetotoxicity

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