Environmental impact of genetically modified crops.

Chapter 13 (Page no: 278)

Safety for human consumption.

Since 1996, over 500 million ha of genetically modified (GM) crops have been grown worldwide. The principal GM crops are soybean, maize, cotton and canola which have been modified for herbicide tolerance (Ht) and/or insect resistance Bacillus thuringiensis (Bt). These crops are all used in monogastric and ruminant livestock production rations as energy and protein feed resources. GM feeds are included either as a whole crop (maize silage), a specific crop component (maize grain) or as co-products or crop residues such as oilseed meals, maize gluten feed, maize stover. GM crops with nutritionally enhanced characteristics for both food and feed are in various stages of development but are not dealt with in this chapter. The concept of a comparative safety assessment which is regarded by regulatory authorities as a robust starting point for the safety assessment for both GM food and feed is discussed. The questions posed by the use of GM feed in livestock production are: does their use influence animal health and productivity and is there any evidence that human health will be affected by the consumption of products such as milk, meat and eggs derived from livestock fed GM feed ingredients? Numerous studies have established that the chemical composition, nutritive value and animal performance of currently used GM feed ingredients are comparable to their near-isogenic non-GM counterpart and also conventional varieties. Although many organizations including the WHO do not consider the consumption of DNA from either conventional or GM crops as a human safety issue, since humans have consumed DNA from a wide variety of sources since evolution began, concern was raised that transgenic DNA (tDNA) and gene products (novel proteins) may accumulate in livestock products derived from animals receiving GM feed ingredients. To date no studies have reported the presence of tDNA that could encode for a gene or gene products in milk, meat and eggs produced by animals receiving GM feed ingredients. There is no evidence to suggest that food derived from animals fed GM products is anything other than as safe and as nutritious as that produced from conventional feed ingredients.

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