Foodborne Toxins

These are the types of toxins AVA screen and test in food for import and export by using sensitive and rapid analysis methods.

1. Mycotoxins:

Aflatoxins B and G in grains and nuts

Aflatoxin M in milk

Patulin in apple juice

Ochratoxins A

2. Marine biotoxins:

Toxigenic strains of algae (Red Tide) -> accumulate in fish and shellfish

Paralytic Shellfish Poison (saxitoxin)

Diarrhetic Shellfish Poison (Okadaic acid)

Amnesic Shellfish Poison (Domoic acid)

3. Bacterial toxins

Staphylococcus aureus (food)

Bacillus cereus (food)

4. Other natural toxicants or allergens

Histamine (scombroid fish)

Taken from: Testing of Food and Food Products , 8 May 2008, http://www.ava.gov.sg/AVA/Templates/AVA-GenericContentTemplate.aspx?NRMODE=Published&NRORIGINALURL=%2fFoodSector%2fFoodTestingAndCertification%2fTestingOfFoodAndFoodProd%2f&NRNODEGUID=%7b036F87DA-E1EF-410B-B53B-9EF71CC3E636%7d&NRCACHEHINT=Guest#TXN

How are foods derived from GM crops assessed for food safety?

According to brochure; Importance Facts you Need to Know About GM Food, from GMAC Singapore, they mentioned that Under international food safety practices, food producers perform tests on the quality, allergenicity, toxicity, composition and nutritional values of food derived from GMOs, before these foods are released. Foods containing new substances through genetic modification then needs to undergo additional testings.

http://www.gmac.gov.sg/Index_Resource_Professors_GENE_ius.html

This is comfirmed with another source from International Service for the Acquisition of Agri-biotech Applications (ISAAA):

Before they are allowed in the market, it has to be tested by the developer and independently evaluated for safety by scientists or experts in nutrition, toxicology, allergenicity, and other aspects of food science. Typical questions that must be address include:

• Does the GM food have a traditional counterpart that has a history of safe use?
• Has the concentration of any naturally occurring toxins or allergens in the food changed?
• Have the levels of key nutrients changed?
• Do new substances in the GM food have a history of safe use?
• Has the food’s digestibility been affected?
• Has the food been produced using accepted, established procedures?

1. GM food tested the same way as foods produced by other methods. The risks of foods from biotech are same as those for conventional foods.
2. They will be judged on their individual safety, allergenicity, toxicity, and nutrition rather than the methods or techniques used to produce them.
3. Any new ingredient added to food through biotech will be subject to pre-market approval in the same way as new food additive (preservative or food color) must be approved before it reaches the market.

Are Foods Derived from GM Crops Safe?, February 2006, ISAAA, Pocket K, No. 3

http://www.isaaa.org/Kc/inforesources/publications/pocketk/default.html

Modified Corn

BIOTECH CORN

Herbicide-tolerant corn

These corn varieties work in a similar manner to herbicide-tolerant soybean. They allow growers better flexibility in using certain herbicides to control weeds that can damage crops.

Insect-resistant corn

This modified corn contains a built-in insecticidal protein from a naturally occurring soil microorganism (Bt) that gives corn plants season-long protection from corn borers. This means most farmers do not have to spray insecticide to protect corn from harmful pests, which can cause significant damage and yield loss in many areas. Bt corn also reduces toxin contamination arising from fungal attack on the damaged grain. The Bt protein has been used safely as an organic insect control agent for over 40 years. Plant Products of Biotechnology, May 2007,

http://www.isaaa.org/kc

Decision Instrument for the assessment and notification of events that may constitute a public health emergency of international concern

www.who.int/foodsafety

Safety assessment of biotech plant food

Toxicological changes:
(a) the presence or increased content of natural toxicants;

(b) the presence of new expressed toxic materials resulting from genetic modifications (e.g., biopesticides);

(c) development of allergenicity

(d) accumulation of toxicants or-microbial contaminants derivedfrom the environment;

(e) changes in the availability of toxins as a result of processing.

Nutritional changes include:
(a) modification of major nutrients micronutrients or antinutrients in the food;

(b) changes in the bioavailability of macro- and/or micronutrients;

(c) changes in nutritional components as a result of processing.

The components of the safety assessment include:
(a) characterization of the host, donor/vector and modified organisms;
(b) characterization of the precision of the process and possibility of pleiotropic or secondary effects;
(c) characterization of novel expressed material ;
(d) characterization of the modified food for wholesomeness.

Taken from: Strategies for assessing the safety of foods produced by biotechnology . WHO,Geneva 1991

Natural Toxins in Food Plants

Toxic Food Components of Plant origin

-> low-molecular-weight endogenous toxins

-> products of secondary metabolism
- species specific and give the plant its particular characteristics
- plant pigments, flavours, and compounds that serve to protect
- impart toxicity to individual when taken orally
- toxins: growth inhibitors, neurotoxins, carcinogens, and teratogens

-> Products of primary metabolism
- energy metabolism (photosymthesis, growth, reproduction)
- they form macronutrients and micronutrients in plants

ALKALOIDS -> glycoalkaloids

Common example:
Solanine, an alkaloid present in small amounts in potatoes while tomatine found in tomatoes

Glycoalkaloids

- ingestion of greened, damaged or sprouted potatoes -> consequence of high levels of glycoalkaloids

- Acute toxicity syndromes in humans have been observed at glycoalkaloid levels of more than 2.8 mg/kg body weight

CYANOGENIC GLYCOSIDES

- taxiphyllin in bamboo shoots, linamarin in cassava,
flaxseeds, and seeds of stone fruits (apricot and peach), seeds of peas and beans such as lima beans, and shell of soya beans, ground almonds powder or paste, marzipan

-clinical signs of acute cyanide intoxication can include: rapid respiration, drop in blood pressure, rapid pulse, dizziness, headache, stomach pains, vomiting, diarrhoea, mental confusion, stupor, cyanosis with twitching and convulsions followed by terminal coma

- acute lethal dose of hydrogen cyanide for humans is reported to be 0.5-3.5 mg/kg bw. Approximately 50-60 mg of free cyanide constitutes a lethal dose for an adult man

LECTINS

- green beans, red kidney beans and white kidney beans

- acute toxicity include severe stomachache, vomiting and diarrhoea

- Lectins can destroy the epithelia of the gastrointestinal
tract, interfere with cell mitosis, cause local haemorrhages, damage kidney, liver
and heart and agglutinate red blood cells

- moist heat to reduce toxicity of lecitin

World Health Organization (WHO). Pyrrolizidine Alkaloids, Environmental
Health Criteria 80. Geneva: WHO; 1988. Available from URL:
http://www.inchem.org/documents/ehc/ehc/ehc080.htm

Australia New Zealand Food Authority. Pyrrolizidine Alkaloids in Food. A
toxicological review and risk assessment. Technical Report Series No.2. ANZFA;
2001. November. Available from URL:
www.foodstandards.gov.au/_srcfiles/TR2.pdf

World Health Organization (WHO). Cyanogenic Glycosides. Toxicological
evaluation of certain food additives and naturally occurring toxicants. WHO Food
Additive Series 30. Geneva: WHO; 1993. Available from URL:
http://www.inchem.org/documents/jecfa/jecmono/v30je18.htm

Questions on Genetically Modified Foods - GMAC

There are some questions on genetically modified food asked and answered at this website:

http://www.gmac.gov.sg/Index_FAQs_Genetically_Modified_Foods.html#seven

1. What foods are produced from GMOs? What is the approximate no. of such products in the market?
2. How long have GM foods been in the market?
3. Are the foods produced from GMOs safe for consumption?
4. Are foods derived from GMOs more nutritious?
5. Are we already consuming foods derived from GMOs?
6. Will foods produced from GMOs carry special labels in Singapore?

Definition of Genetically Modified Organisms (GMOs) [3]

• Plants, animals or bacteria that have one or a few selected genes from other organisms introduced
• Use of modern gene technology
• Food and feed which contain or consist or produced from GMOs -> genetically modified (GM) food or feed
  

Import of Genetically Modified Organisms (GMOs)
Guidelines from: Genetic Modification Advisory Committee of Singapore (GMAC) [1]

Purpose of guidelines: [2]
1. the assessment of risks of agriculture-related GMOs to human health and the environment; and
2. the approval mechanisms for their release in Singapore

Process for the evaluation and approval of agriculture-related GMOs in Singapore [2]

Proponent - any person, firm, company, institution or organisation planning to release agriculture-related GMOs into Singapore

Benefits of GM Food:

1. Increase in nutrient content of food
2. Decrease allergenicity
3. Enhanced taste and quality
4. Reduced maturation time
5. Increased yields and stress tolerance
6. Improved resistance to disease, pests, and herbicides
7. New products and growing techniques
8. "Friendly" bioherbicides and bioinsecticides
9. Conservation of soil, water, and energy
10. Bioprocessing for forestry products
11. Better natural waste management
12. More efficient food production
13. Increased food security for growing populations

Disadvantages of GM Food: [4]

1. Potential human health impact: allergens, transfer of antibiotic resistance markers, unknown effects
2. Potential environmental impact: unintended transfer of transgenes through cross-pollination, unknown effects on other organisms (e.g., soil microbes), and loss of flora and fauna biodiversity
3. Biopiracy—foreign exploitation of natural resources
4. Violation of natural organisms' intrinsic values
5. Tampering with nature by mixing genes among species
6. Objections to consuming animal genes in plants and vice versa
7. Labeling: Not mandatory in some countries (e.g., United States) and mixing GM crops with non-GM confounds labeling attempts

[1] Import, Export and Transshipment of Plants. (2008, may 8).Available at: http://www.ava.gov.sg/AVA/Templates/AVA-GenericContentTemplate.aspx?NRMODE=Published&NRORIGINALURL=%2fAgricultureFisheriesSector%2fImportExportTransOfPlants%2f&NRNODEGUID=%7b1FB21A62-549B-4673-81ED-E9B18E4312BA%7d&NRCACHEHINT=Guest#gmo [Accessed on 3 June 2008]
[2] Singapore Guidelines on the Release of Agriculture-related GMOs. (2007). Available at: http://www.gmac.gov.sg/Index_Singapore_Guidelines_on_the_Release_of_Agriculture_Related_GMOs.html [Accessed on 3 June 2008]
[3] http://www.ava.gov.sg/FoodSector/FoodSafetyEducation/Food+Facts/AtoZOnFoodSafety/index.htm
[4] Genetically Modified Foods and Organisms. (2007 July 24). Available at: http://www.ornl.gov/sci/techresources/Human_Genome/elsi/gmfood.shtml [Accessed on 4th May 2008]

What is GM Food?

1. GM foods a.k.a genetically engineered (GE) foods

2. Contains ingredient(s) modified by a technique à gene technology

3. Alter certain characteristics of a food crop by:
- Introducing genetic material and proteins from another source
- Usually change one gene of the 30,000 — 50,000 or genes making up an organism.

4. Horticulturalists and biologists -> plants and animals -> cross breeding -> promote more desirable characteristics (tulips with new colours)

5. Discovery of genes -> control the development of an organism-> insert or remove genes -> eliminate generations of cross breeding for the desirable characteristics to appear

E.g -> Corn plant -> gene: resistant to insect attack
E.g -> Wheat plant -> gene: less water to grow -> more desirable for Australian countries

Taken from: http://www.foodstandards.govt.nz/foodmatters/gmfoods/

Diagram of how bacterial gene inserted to make crop pest resistant:

Reference:

GMAC. (2007). Genetically Modified Organism. Available at: http://www.gmac.gov.sg/Index_FAQs_Genetically_Modified_Organisms.html