FEDERAL UNIVERSITY 0F FEDERAL UNIVERSITY 0F AGRICULTURE AGRICULTURE

COLLEGE OF FOOD SCIENCE AND COLLEGE OF FOOD SCIENCE AND HUMAN ECOLOGYHUMAN ECOLOGY

FEDERAL UNIVERSITY 0F FEDERAL UNIVERSITY 0F AGRICULTURE AGRICULTURE

COLLEGE OF FOOD SCIENCE AND COLLEGE OF FOOD SCIENCE AND HUMAN ECOLOGYHUMAN ECOLOGYW E L C O M E !W E L C O M E !

To the class:To the class:Course code:FST 507Course code:FST 507

Course title: FOOD ADDITIVES,TOXICOLOGY Course title: FOOD ADDITIVES,TOXICOLOGY AND SAFETYAND SAFETY

11STST SEMESTER, 2011/2012 SESSION SEMESTER, 2011/2012 SESSION

Lecturer: PROF F. O. HENSHAWLecturer: PROF F. O. HENSHAWE-mail E-mail henofcpc@yahoo.comhenofcpc@yahoo.com

fohenshaw@unaab.edu.ngfohenshaw@unaab.edu.ngPhone: 234 8034056311Phone: 234 8034056311

Course requirements• Number of units: 3 units• Lecture period: 2 hour /week(30

hours/semester)• 75% attendace is required to qualify to sit final

examination• One Practical period 3hour/week• Grading

take home assignment 10%A short quiz in class 20%Final Examination70%

Course Learning Objectives

Upon successful completion of the course students should:

• Have broad base knowledge about sources, nature and control of toxic substances in human food system

• Acquire critical thinking and analytical skills in risk assessment

• Have a high level of understanding and interpretative capacity in food science and toxicology interface.

COURSE OUTLINE

1. DEFINITIONS OF TERMS; TOXICOLOGY, ADDITIVES AND SAFETY

2. Toxicity and Safety evaluation

3. Naturally occuring Toxins MycotoxinsGlycoalkaloidsGlucosinolatesAntinutritional factorsPhycotoxins

4. Food additivesAntioxidantsPreservativesColourantsEmulsifiers and StabilisersSweetnersMiscellaenous Additives

5. Effect of Processing on Toxicity6. Safety of Food additives7. Food Processing and Toxicity8. Irradiation and Toxicity9. Microbial Toxicity

FOOD ADDITIVES—Any substance/mixture of substances other than the basic component that is added to food as a result of any aspect of processing, storage and preservation

TOXICOLOGY: multi-disciplinary application of Scientific knowledge to the study of toxins and their effects on people, animals, wildlife and the environment.

• Toxicology is the most diversified of all Scientific disciplines, so Toxicologists usually specialize in some aspect of toxicology e.g– Medical Toxicology/ Clinical Toxicology:

diagnosis and treatment of human diseaeses caused by poisons

– Veterinary Toxicology: diagnosis and treatment of diseases of domesticated and wildlife caused by poisons

• Food toxicology is the study of the nature, properties, effects and detection of toxic substances in food and their disease manifestation in humans

• Forensic Toxicology: deals with the legal and medical aspects of poisons in people and animals;

• Environmental Toxicology- deals with effects of pollutants on the environment and wildlife

• Safety: is the absence of evidence of toxicity

• Toxicity is ability to cause harm/adverse effect

• A toxin/poison is difficult to define as many substances present in food would have adverse/toxic effects if taken in large/sufficient dose

NATURAL vs SYNTHETIC CHEMICALS

• Are natural chemicals safer than synthetic chemicals?

• Which set pose a greater risk?• Which set is more amenable to control

and regulation?• Fundamental concept of Toxicology: all

substances can be toxic it is a matter of DOSE

• Safety is relative and there is no absolute safety

• Thus there are toxic and non toxic doses for any substance

• Frequency-response curve: a plot of the % of individual with specific response as a function of dose

Cumulative response-curve

(compounds A and B)

Dose-response curve

• TOXICOLOGICAL TERMSToxin /Toxicant : A substance that has been shown to present some significant degree of possible risk when consumed in sufficient quantity by humans or animals

Natural/Inherent :Toxicants occur in Foods as a result of biosynthetic origin

• Acute Toxicity• Chronic Toxicity• Sub-chronic feeding test• Maximum tolerated dose (MTD)• No observable adverse effect level

(NOAEL)• Acceptable daily intake (ADI)• Lethal dose fifty (LD50)

• Tumor dose fifty (TD50)

• GRAS• Acute toxicity: toxic response ,often

immediate, induced by single exposure. • The acute toxicity of a substance is

defined by its LD50 / lethal dose that will kill 50% of a group of exposed animals

• LD50 is also used to determine the level of toxicity

LD50 (/Kg body weight

substance

200mg Caffeine

100ng Botulinumtoxin

40g Sodium chloride

LD50 Toxicity Level

≤ 1mg Extremely Toxic

1-50mg Highly toxic

50-500mg Moderately toxic

>500mg Non Toxic

• Chronic toxicity: Toxic effect that requires some time to develop, e.g cancer.

• Testing for chronic toxicity involve continuous feeding of the test substance to rodents for 20-24 months.

• By analogy to LD50, the amount of a carcinogen required to induce cancer in 50% of a group of exposed animal is referred to as TD50

,

• New approaches to safety evaluation may be required for Genetically modified foods|(GMOs)

• Comparative toxicology concept

• New approaches to safety evaluation may be required for Genetically modified foods|(GMOs)

• Comparative toxicology concept

Toxicology and risk analysis

• Risk assessment• – Scientific evaluation of the

probability of harm resulting from exposure to toxic substances.

• Risk communication• – The science of communicating

effectively in situations that are of high concern, sensitive, or controversial. Risk communication principles serve to create an appropriate level of outrage, behavior modification, or mitigating response, that is in direct proportion to the level of risk or hazard.

• Risk management• – Risk management is the decision-making

process involving considerations of political, social, economic and science/engineering factors with relevant risk assessments relating to a potential hazard so as to develop, analyze and compare options and to select the optimal response for safety from that hazard.

• Risk characterization• – A description of the nature and

magnitude of health risk that combines results of exposure assessment and hazard identification and describes the uncertainty associated with each step.

• Protocols have been established for safety evaluation of foods and substances used in foods

• Acute toxicity • Genetic toxicity• Subchronic• Chronic• Teratogenesis

• Traditional high dose feeding of a

few rats/other rodents• A safety margin of a 100-fold is

usually applied from the NOAEL (no observable adverse effect level) to determine safe dose for man, i.e the ADI (acceptable daily intake).

• New approaches to safety evaluation may be required for Genetically modified foods|(GMOs)

• Comparative toxicology concept

Natural plant Toxins• Naturally ocurring toxic components in

plant foodstuffs• Have negative effects on bio availability

of nutrients ;anti- nutritional factors/anti-nutrients

• Produced as part of plant defense against bacteria, insects and other threats

• Glycoalkaloids– Are steroidalkaloids coupled to one or

more monosaccharides• Occurrence: the genus Solanum

e.g; eggplant, potato, tomatoes– Potato; α-Solanine and α- Chaconine– Tomato: TomatineProperties

fairly heat stable ,not decomposed during cooking,not water soluble

• Average composition in potato: 20-100mg/kg fresh tissue

• Concentration is higher in sprouts, peels and green areas

• ~3mg/kg body weight can induce toxicity

• Human intoxication:Gastro intestinal disorder (abdominal pain, nausea, and diarrhea)

• > LD50 admnister as oral dose in sheep, rat and mice:500, 600, and 100mg /kg respectively

Structure of solanine/chaconine

• Goitrogens: components that exhibit adverse effect on the thyroid gland function e.g;– Glucosinolates– Cyanogenic glucosides– Soy factorGlucosinolates are sulphur- containing

glucosideOccurrence: plant family crucifereae of

the genus. E.g Brassica ebbage, Cauliflower flower,