Toxins

Question 1

Describe the different categories of manmade contaminants in food

Answer 1

1. Agricultural chemicals
   * Antibiotics
   * Pesticides
   * Anabolic agents
2. Chemicals from food package materials
   *Monomers
   *Plasticisers

Question 2

Describe the different categories of natural contaminants in food

Answer 2

1. Constituents of natural food products
   *Oxalates
2. Microbiological contaminants of natural food products (Mycotoxins)
   * Aflatoxins
3. Non-microbiological contaminants of natural food products
   *Saxitoxin

Question 3

List the problems associated with antibiotic use in milk

Answer 3

• Antibiotic residues in food
• Development of resistant bacteria

Question 4

Describe a suitable method of analysis for antibiotics in milk.

Answer 4

Specific test e.g sulphadimide in porcine tissue by HPLC
Extract with Dichloromethane (3Cleanup
Evaporate under nitrogen, redissolve in acetonitrile
Acetonitrile/water (35:65) as mobile phase

Question 5

Describe the 2 sources of contaminants associated with plastic packaging

Answer 5

Monomers - Tendency of vinyl chloride to leach out of PVC, is a potential problem if food is stored for long periods in PVC containers.
Plasticisers - The plasticisers most commonly used in PVC Dioctyl adipate (DOA)
* May mimic female sex hormones
* Affect male fertility and increase the incidence of other disorders of the male reproductive system.

Question 6

Antibiotics are regularly given to livestock destine for the food sector, List the reasons for their usage

Answer 6

i. individual animals treated for a specific infection
ii. treatment to control or prevent the likely occurrence of infection in a herd
iii. feed additives to reduce subclinical disease