<p style="text-align: justify;">Cotton (<i>Gossypium hirsutum</i> L.) is primarily grown for its seed bolls that produce fibres used in numerous textile products. The major producers of cotton seed and lint are China, the United States, India, Pakistan, Brazil, Uzbekistan and Turkey.</p>

<p style="text-align: justify;">About two thirds of the harvested cotton crop is seed, which is separated from the lint during ginning. The cotton seed is crushed to produce cottonseed oil, cottonseed cake (meal), and hulls. Cottonseed oil is used primarily as a cooking oil, in shortening and salad dressing, and is used extensively in the preparation of snack foods such as crackers, cookies and chips. The meal and hulls are an important protein concentrate for livestock, and may also serve as bedding and fuel. Linters, or fuzz, which are not removed in ginning, are used in felts, upholstery, mattresses, twine, wicks, carpets, surgical cottons, and in industrial products such as rayon, film, shatterproof glass, plastics, sausage skins, lacquers, and cellulose explosives.</p>

<p style="text-align: justify;">Tobacco budworm (<i>Heliothis virescens</i>), pink bollworm (<i>Pectinophora gossypiella</i>), and cotton bollworm (<i>Helicoverpa zea</i>) are three of the most destructive pests of cotton. In the United States alone, the combined costs of costs of control and yield loss attributed to these pests is up to $476 million per year. In Egypt, China and Brazil, pink bollworm commonly causes cotton losses of up to 20 percent.</p>

<p style="text-align: justify;">More insecticides are applied to conventionally grown cotton than any other single crop. Each year cotton producers around the world use nearly $2.6 billion worth of pesticides such as aldicarb, phorate, methamidophos and endosulfan. Cotton pests, such as the tobacco budworm, have developed some resistance to many of the insecticides used to control them. In regions where insecticide-resistant populations have developed, budworm damage can reduce yields by 29%, despite an average of six insecticide applications each growing season.</p>

<p style="text-align: justify;">Cotton lines MON531, MON757, and MON1076 were genetically engineered to resist cotton bollworm, tobacco budworm and pink bollworm by producing their own insecticide. These lines were developed by introducing the <i>cry1Ac</i> gene, isolated from the common soil bacterium <i>Bacillus thuringiensis</i> (<i>Bt</i>), into a cotton line by <i>Agrobacterium</i>-mediated transformation. The <i>cry1Ac</i> gene produces the insect control protein Cry1Ac, a delta-endotoxin. The Cry1Ac protein produced in lines MON531, MON757, and MON1076 is almost identical to that found in nature and in commercial <i>Bt</i> spray formulations. Cry proteins, of which Cry1Ac is only one, act by selectively binding to specific sites localized on the lining of the midgut of susceptible insect species. Following binding, pores are formed that disrupt midgut ion flow, causing gut paralysis and eventual death due to bacterial sepsis. Cry1Ac is insecticidal only when eaten by the larvae of lepidopteran insects (moths and butterflies), and its specificity of action is directly attributable to the presence of specific binding sites in the target insects. There are no binding sites for delta-endotoxins of <i>B. thuringiensis</i> on the surface of mammalian intestinal cells, therefore, livestock animals and humans are not susceptible to these proteins.</p>

<p style="text-align: justify;">Cotton lines MON531, MON757, and MON1076 were tested in field trials in the United States beginning in 1990. Agronomic characteristics such as yield, boll size, plant vigour, growth, morphology, germination and flowering were found to be within the range for commercial cotton lines. Disease susceptibility remained unchanged in the transgenic lines, and the processing qualities of cotton lint, such as fibre length and strength, were also within the norms for conventional cotton varieties. It was demonstrated that MON531, MON757, and MON1076 did not exhibit weedy characteristics and had no effect on non-target organisms or the general environment. The transformed lines were not expected to impact on threatened or endangered species.</p>

<p style="text-align: justify;">Cotton plants are primarily self-pollinating, but insects, especially bumblebees and honeybees, also distribute cotton pollen. Cotton can cross-pollinate with compatible species including <i>G. hirsutum</i> (wild or under cultivation), <i>G. barbadense</i> (cultivated Pima cotton), and <i>G. tomentosum</i>. Overall, the probability of gene transfer to wild species in unmanaged ecosystems is low due to the relatively isolated distribution of Gossypium species, different breeding systems, and genome incompatibility. Assuming proximity, synchronicity of flowering and availability of insects, MON531, MON757, and MON1076 may freely hybridize with other <i>G. hirsutum</i> varieties.</p>

<p style="text-align: justify;">Regulatory authorities in the United States have mandatory requirements for developers of <i>Bt</i> cotton to implement specific Insect Resistant Management (IRM) Programs. The potential for <i>Bt</i>-resistant insect populations to develop increases as acreages planted with transgenic <i>Bt</i> cotton hybrids expand. Hence, these IRM programs are designed to reduce this potential and prolong the effectiveness of plant-expressed <i>Bt</i> toxins, and the microbial <i>Bt</i> spray formulations that contain these same toxins.</p>

<p style="text-align: justify;">The livestock feed safety of MON531, MON757, and MON1076 was established based on several standard criteria. As part of the safety assessment, the nutritional composition of cottonseed was tested and found to be equivalent to conventional cotton, as shown by analyses of key nutrients, including proximates (crude protein, crude fat, crude fibre, ash and gross energy), tocopherols, and amino acid and fatty acid composition. Assays were completed to determine levels of anti-nutritional factors such as aflatoxins, gossypol, and dihydrosterculic fatty acids and there were no differences in cottonseed samples from the transgenic and conventional cotton lines. Cottonseed products (raw meal, toasted meal, kernel, refined oil) were analyzed and found to be similar in composition to conventional cotton. The nutritional equivalence of MON531, MON757, and MON1076 to conventional cotton was confirmed in feeding trials with rats and quail, which did not experience any deleterious effects when fed raw cottonseed meal from cotton line 531.</p>

<p style="text-align: justify;">Refined cottonseed oil and cellulose from processed linters of cottonseed are the only cotton products consumed by humans, and are subjected to processing treatments that would be expected to remove and/or destroy DNA and protein. Nevertheless, toxicity of MON531, MON757, and MON1076 was assessed by analysis of the naturally occurring toxins gossypol and cyclopropenoid fatty acids (sterculic and malvalic acid) in cottonseed and refined oil. The deduced amino acid sequences of Cry1Ac was compared to the amino acid sequence of known protein toxins and no significant similarities were found.</p>

<p style="text-align: justify;">Refined cottonseed oil and cellulose from linters are devoid of protein and, given that most allergens are proteins, consumption of oil and cellulose is unlikely to provoke an allergic reaction. The potential for allergenicity was assessed based on studies that included digestive degradation, sequence similarity to known allergens, and lack of protein in food derived from cotton. Cry1Ac showed no significant protein sequence homology to a database of known allergens and, unlike known allergenic proteins, Cry1Ac is rapidly degraded when exposed to simulated gastric fluids.</p>
