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DP-3Ø5423-1 (305423) is a genetically modified soybean that was produced by biolistic insertion of the gm-fad2-1 gene fragment and gm-hra genes into the germline of soybean seeds. Expression of gm-fad2-1 results in greater concentrations of oleic acid (18:1) by suppressing expression of the endogenous FAD2-1 gene, which encodes an n-6 fatty acid desaturase enzyme that catalyzes desaturation of 18:1 to linoleic acid (18:2). The GM-HRA protein expressed by the gm-hra gene is a modified version of the soybean acetolactate synthase enzyme that is used as a selectable marker during transformation. A 42-d feeding trial was conducted with broiler chickens to compare the nutritional performance of 305423 soybeans with nontransgenic soybeans. Diets were prepared using processed fractions (meal, hulls, and oil) from 305423 soybean plants. For comparison, additional diets were produced with soybean fractions obtained from a nontransgenic near-isoline (control) and nontransgenic commercial Pioneer brand varieties (93B86, 93B15, and 93M40). Diets were fed to Ross x Cobb broilers (n = 120/group, 50% male and 50% female) in 3 phases. Starter, grower, and finisher diets contained 26.5, 23, and 21.5% soybean meal, respectively. Soybean hulls and oil were added at 1.0 and 0.5%, respectively, across all diets in each phase. No statistically significant differences were observed in growth performance (BW, mortality, feed efficiency), organ yield (liver and kidney), or carcass yield (breast, thigh, leg, wing, and abdominal fat) variables between broilers consuming diets prepared with isolated fractions from 305423 or near-isoline control soybean. Additionally, all performance and carcass variables from control and 305423 soybean treatment groups fell within tolerance intervals constructed for each response variable using data from broilers fed diets prepared with reference soybean fractions. Based on the results from this study, it was concluded that 305423 soybeans were nutritionally equivalent to non-transgenic control soybeans with a comparable genetic background.

Maize line 1507, containing event DAS-Ø15Ø7-1 (1507), is a genetically modified (GM) maize plant that expresses the cry1F gene from Bacillus thuringiensis (Bt) sbsp. aizawai and the phosphinothricin-N-acetyltransferase (pat) gene from Streptomyces viridochromogenes throughout the plant including in the grain expression of the Cry1F protein confers in planta resistance to the European corn borer (ECB; Ostrinia nubilalis Hübner: Crambidae) and other lepidopteran pests. Expression of the PAT protein confers tolerance to the herbicidal active ingredient glufosinate-ammonium. The current study evaluated the nutritional performance of rats fed diets containing 1507 maize grain in a subchronic rodent feeding study. The grains in this study, 1507, its near-isogenic control (33P66), and a non-GM commercial hybrid (33J56) contained similar amounts of proximates, amino acids, minerals, anti-nutrients, and secondary metabolites. The subchronic feeding study compared standard toxicology response variables in rats fed diets containing 1507 maize grain with those in rats fed diets containing non-GM maize grains. All diets were prepared according to the specifications of PMI Nutrition International, LLC Certified Rodent LabDiet 5002 (PMI) 5002). Diets were fed ad libitum to Sprague-Dawley rats for approximately 90 days. In-life response variables included indicators of dietary performance and weekly evaluations for clinical signs of toxicity. No toxicologically significant differences were observed in the nutritional performance variables, clinical and neurobehavioral signs, ophthalmology, clinical pathology (hematology, clinical chemistry, coagulation, and urinalysis), organ weights, and gross and microscopic pathology between any pair of treatment groups. These results demonstrate that 1507 maize grain is as safe and as nutritious as non-GM maize grain.

Three case studies are described; each represents a specific application of the IFBC/ILSI decision tree as prescribed by Metcalfe et al.1 to assess the allergenic potential of foods derived from genetically engineered crop plants. The case studies include high methionine soybean, high oleic soybean and Herculex TM 1 Insect Protected Maize, the results of which support/validate the use of the IFBC/ILSI decision tree for the prescribed applications.

Publisher Summary This chapter describes the toxicology of several chloracetanilide herbicides, a subclass of the acetamides that have as a common structural feature a C1H2C group as the R1 substitution. It is known that this class of herbicides inhibits the biosynthesis of lipids, alcohols, fatty acids, proteins, isoprenoids, and flavonoids. By inhibiting synthesis of various terpenoid precursors, these herbicides appear to interfere with the production of gibberellin. It has been shown that chloracetanilides are detoxified in plants by conjugation with glutathione. The study includes the chemical identities, structures, and properties of various chloracetanilide herbicides. They are alachlor, acetochlor. butachlor, metachlor, and propachlor. Chronic administration of chloracetanide herbicides has resulted in the production of nasal, stomach, liver, and thyroid tumors in rats. Most tumors occurred at excessively toxic dose levels, at or above the MTD. A weight-of-evidence analysis of mutagenicity results indicates that chloracetanides have no significant genotoxic potential in mammalian systems. This suggests that the oncogenic responses in rats arise through non-genotoxic, threshold-sensitive mechanisms. Butachlor and alachlor are close structural analogs that produce the same stomach tumors in rats as a result of prolonged exposure. Separate studies were conducted to determine if alachlor, acetochlor, and butachlor produce thyroid tumors. The results of these studies showed that the administration of each chloracetanilide at the dose level producing thyroid neoplasia in the chronic studies caused significant increases in liver weight and T4-UDPGT activity, serum TSH levels, and thyroid weight at several time points.

A genetically modified maize (Zea mays L.) line that contains the Optimum GAT trait (event DP-O9814O-6; 98140) was produced by integration of the gat4621 and zm-hra genes. The expressed GAT4621 and ZM-HRA proteins confer tolerance to the herbicidal active ingredient glyphosate and acetolactate synthase-inhibiting herbicides, respectively. The objective of this study was to compare the nutritional performance of 98140 maize grain to nontransgenic maize grain in a 42-d feeding trial in broiler chickens. Diets were prepared using grain from untreated 98140 plants and from plants treated with an in-field application of herbicides (98140 + Spray). For comparison, additional diets were produced with maize grain obtained from the nontransgenic near-isogenic control (control) and nontransgenic commercial reference Pioneer brand hybrids 33J56, 33P66, and 33R77. Diets were fed to Ross x Cobb broilers (n = 120/group, 50% male and 50% female) in 3 phases: starter, grower, and finisher containing 58.5, 64, and 71.5% maize grain, respectively. No statistically significant differences were observed in mortality, growth performance variables, or carcass and organ yields between broilers consuming diets produced with maize grains from unsprayed or sprayed 98140 and those consuming diets produced with near-isogenic control maize grain. Additionally, all performance and carcass variables from control, 98140, and 98140 + Spray test maize treatment groups were within tolerance intervals constructed using data from reference maize groups. Based on these results, it was concluded that 98140 maize grain (unsprayed or sprayed with a herbicide mixture) was nutritionally equivalent to nontransgenic control maize with comparable genetic background.

This chapter describes the toxicology of chloracetanilide herbicides such as alachlor, acetochlor, butachlor, metolachlor, and propachlor. Eye and skin irritation studies conducted in rabbits showed alachlor to be non-irritating to the eye and slightly irritating to the skin. Alachlor produced skin sensitization in guinea pigs. Acetochlor has been shown to be practically nonirritating to the eyes and skin of rabbits. A dermal sensitization study in guinea pigs was positive. In studies with rabbits, butachlor was practically non-irritating to the skin and moderately irritating to the eye; dermal sensitization was observed in a study with guinea pigs. Metolachlor did not produce eye or skin irritation in rabbits; the material was positive in a dermal sensitization study with guinea pigs. Eye and skin irritation studies conducted in rabbits showed propachlor to be severely irritating to the eye and slightly irritating to the skin. Propachlor produced skin sensitization in guinea pigs. The herbicidal mode of action for chloracentanilides is not totally understood. It is known that this class of herbicides inhibits the biosynthesis of lipids, alcohols, fatty acids, proteins, isoprenoids, and flavonoids. By inhibiting synthesis of various terpenoid precursors, these herbicides appear to interfere with the production of gibberellins.