New Genetics, Food & Agriculture: Scientific Discoveries - Societal Dilemmas

 

Table 3.1. Implications of Genetically Modified Foods and Crops for Human Health

Note: For references cited in this table, direct links are provided to the appropriate section of the Annotated Bibliography

Issue 

Scientific convergence

Scientific divergence

Gaps in knowledge

 

Issue 1: Safety of GM foods for human consumption
Overview

 

Present GM foods on market are considered safe for human consumption. (FAO/WHO 2000; 2001a)

No documented cases of ill effects from GM food consumption. (OECD 2000a,b; 2001a)

 

 Long term effects unknown for GM foods, as well as most foods. Difficult to detect long-term effects due to many confounding factors and genetic variability in foods and related effects in the population. (Kuiper et al 2001) 
Risk issues for GM food safety assessments

Increased risks of allergenic and/or toxic compounds in foods due to presence of newly inserted proteins or marker genes.

Gene technology may increase or decrease levels in food of naturally occurring allergenic proteins or introduce new proteins or other compounds with potential for allergenic, toxic or food intolerant reactions.
If any increased levels of allergens or potential new allergens detected, the product is not commercialized.
Transfer of genes from commonly allergenic foods is discouraged. (FAO/WHO 2000)

 

 Proteins from sources not previously used in human food are more difficult to assess for safety. Present methods compare new protein with known allergens and also test for heat stability and enzyme digestibility.  If new protein is heat unstable and easily digestible, low allergenic risk.  Heat stable proteins pose higher risks of allergenicity. (Lehrer, 2000; FAO/WHO 2000, 2001).
Any increases in pollen allergenicity should be checked. (RS)
Antibiotic resistance development in human and/or animal pathogens.

Minimal risk of antibiotic markers increasing antibiotic resistance in human and animal pathogens.  Antibiotic markers are being phased out in response to consumer concerns. (FAO/WHO 2000; OECD 2001a)

 
Unintended effects

 

 Unintended food compositional changes may occur during genetic improvement, by conventional plant breeding and/or by gene technology. Effects detected by chemical analysis of known nutrients and toxicants (targeted approach). Possibility of unintended effects may increase in plants with extensive genetic modification and altered biochemical pathways, producing new products with modified nutritional content (eg vitamins, starch, oil content).

 
Horizontal gene transfer from GM foods to human/animal gut microflora Horizontal gene transfer to gut microflora may occur, at low frequency. Risks need to be assessed on case by case basis. New profiling/finger-printing techniques may be useful (non-targeted approach) to assay whole foods (Kuiper et al 2001).

 
Issue

 

 Scientific convergence Scientific divergence   Gaps in knowledge  

Issue 2:  Adequacy of methods for food safety assessments

Present products  
(Main commercial products approved are corn, soybean, rapeseed, potato, papaya and tomato modified for insect resistance,  herbicide tolerance,  virus resistance and/or delayed ripening).  

 

Present risk assessments based on concept of substantial equivalence as part of a safety evaluation framework.  This concept considers the existing food supply is safe based on a history of safe use, although many foods contain anti-nutrients and toxicants that can cause deleterious effects at certain levels and modes of consumption.

Several inter-governmental panels satisfied with present approaches used to assess safety of GM foods in commercial use today. (e.g. FAO/WHO, 2000, 2001a,b OECD 2000)

National food safety systems have approved selected GM foods for human consumption and/or animal feed (e.g. Argentina, Australia, Canada, China, South Africa, Spain, UK, USA).

Consensus needs to be established on the practical applications of substantial equivalence concepts (Kuiper et al 2001)

Precautionary approaches t risk assessment require that in areas of uncertainty there should be evidence of no harm.

 

Future products

Plants may be genetically modified to change complex traits such as taste, aroma, and/or nutrient content.

New products may result from extensive modification of biochemical pathways, addition of new pathways, and/or modified toxin-producing pathways.  



Comparative safety assessments are used to establish degree of substantial equivalence with most appropriate counterpart.

Compositional analysis of key components (nutrients and toxicants) as well as phenotypic and agronomic characteristics of the GM plant is the basis of assessment of substantial equivalence.

A GM food may be considered:
(1) substantially equivalent; 
(2) substantially equivalent except for the inserted gene; 
(3) not equivalent at all.

Food safety assessment strategies need to be developed on case-by-case basis, with the extent of risk assessments being proportionate to the likely risks involved (OECD consensus docs).

 

The extent of food safety assessments required for specific cases is debated.  If substantial equivalent (SE) – no further testing is required.  If SE except for one trait further safety testing concentrates on this trait, and its potential for increased toxicity, or allergenicity, gene transfer to gut microflora, and other risk factors (Kuiper et al 2001).

 

New profiling finger-printing  techniques need to be further developed and validated to assess content of whole foods. The interpretation of data from whole foods analyses, to assess significance of any compositional changes in foods needs to be refined (Kuiper et al 2001, IUNS/IUTOX 2002)
Issue    

 

 Scientific convergence   Scientific divergence Gaps in knowledge

Issue 3: Benefits of GM Foods

Direct health benefits

  Nutritionally improved foods

    

 

      
     

    

      
          Starch content

   

 





Improving nutritional content of foods is scientifically possible (eg Vitamin A in rice and Indian mustard).  


Micronutrient content can be varied genetically  (eg iron in rice) (IUNS/IUTOX 2002)

Oil content of rapeseed modified to increase lauric acid content. 

Starch quantity and quality can be modified, to increase the glycemic index of foods (eg barley) 

 



Need to demonstrate nutritionally significant levels of vitamins and minerals are genetically expressed and nutritionally available in new foods, and that there are no unintended effects (IUNS/IUTOX 2002)		  



Benefits need to be better documented.  
ISAAA 2001, 2002a,b.

Pest/ disease tolerant crops  

      Less chemical pesticide use

      Less mycotoxins in food  (potential carcinogens).

 

       Less toxins in food  

 




Substantial reductions in pesticide use on broad acre crops (CAST 2002 )

Mycotoxin levels reduced in Bt corn

Toxin levels may be reduced experimentally (eg cassava with lower cyanide levels)  

 

 

 

 
Vaccine and/or pharmaceutical  production in crops   Vaccines able to be produced in crops.

 

 

 Additional crop management and regulatory issues involved for crops used to produce pharmaceuticals and/or industrial products in order to keep them out of the human food chain.
Issue Scientific convergence  

 

 Scientific divergence   Gaps in knowledge  

Issue 4: Identification of GM foods

Post-market surveillance  

 

Safety of food needs to be determined before new foods are approved for market, rather than seek to monitor after effects.  



Post market surveillance difficult and may not yield useful data on long-term and/or unintended effects, due to dietary complexity and genetic variability in the population.

 

May be useful for following allergenic or food intolerance reactions in specific parts of the population.     
Labelling  

 

 Labelling can inform consumers on the content, as well as on the process itself.

 

Back to Contents