An environmental risk assessment of IPD079Ea: a protein derived from Ophioglossum pendulum with activity against Diabrotica spp.In maize.

Farmers in North America face significant pressure from insects in their maize fields, particularly from corn rootworm (Diabrotica spp.). Research into proteins capable of insecticidal activity has found several produced by ferns. One protein, IPD079Ea, was derived from Ophioglossum pendulum and has shown activity against corn rootworm. An environmental risk assessment was conducted for maize event DP-915635-4, which provides control of corn rootworms via expression of the IPD079Ea protein. This assessment focused on IPD079Ea and characterized potential exposure and hazard to non-target organisms (NTOs). For exposure, estimated environmental concentrations (EECs) were calculated. For hazard, laboratory dietary toxicity studies were conducted with IPD079Ea and surrogate non-target organisms. Environmental risk was characterized by comparing hazard and exposure to calculate the margin of exposure (MOE). Based on the MOE values for DP-915635-4 maize, the IPD079Ea protein is not expected to result in unreasonable adverse effects on beneficial NTO populations at environmentally relevant concentrations.

Agronomic and compositional assessment of genetically modified DP23211 maize for corn rootworm control.

DP23211 maize was genetically modified (GM) to express DvSSJ1 double-stranded RNA and the IPD072Aa protein for control of corn rootworm (Diabrotica spp.). DP23211 maize also expresses the phosphinothricin acetyltransferase (PAT) protein for tolerance to glufosinate herbicide, and the phosphomannose isomerase (PMI) protein that was used as a selectable marker. A multi-location field trial was conducted during the 2018 growing season at 12 sites selected to be representative of the major maize-growing regions of the U.S. and Canada. Standard agronomic endpoints as well as compositional analytes from grain and forage (e.g., proximates, fibers, minerals, amino acids, fatty acids, vitamins, anti-nutrients, secondary metabolites) were evaluated and compared to non-GM near-isoline control maize (control maize) and non-GM commercial maize (reference maize). A small number of agronomic endpoints were statistically significant compared to the control maize, but were not considered to be biologically relevant when adjusted using the false discovery rate method (FDR) or when compared to the range of natural variation established from in-study reference maize. A small number of composition analytes were statistically significant compared to the control maize. These analytes were not statistically significant when adjusted using FDR, and all analyte values fell within the range of natural variation established from in-study reference range, literature range or tolerance interval, indicating that the composition of DP23211 maize grain and forage is substantially equivalent to conventional maize represented by non-GM near-isoline control maize and non-GM commercial maize.

Metabolic Basis for Nonlinearity in 1,3-Dichloropropene Toxicokinetics and Use in Setting a Kinetically-derived Maximum Inhalation Exposure Concentration in Mice.

1,3-Dichloropropene (1,3-D) showed a statistically increased incidence of bronchioloalveolar adenomas in male B6C3F1 mice at 60 ppm air concentration during previous chronic inhalation testing. No tumors were observed in female mice, nor in either sex of F344 rats up to 60 ppm, the highest dose tested. Therefore, to understand if lung tumors observed in high dose male mice are due to saturation of metabolic clearance, the linearity of 1,3-D concentrations in mouse blood was investigated on day 15 of repeated nose-only inhalation exposure to 0, 10, 20, 40, 60, 90, and 120 ppm (6 h/d, 7 d/week). Additional groups were included at 20, 60, and 120 ppm for blood collection at 1.5 and 3 h of exposure and up to 25 or 40 min post-exposure to determine area-under-the-curve. The data provide multiple lines of evidence that systemic exposures to 1,3-D in the mouse become nonlinear at inhalation exposure levels of 30 ppm or above. A reduction in minute volume occurred at the highest exposure concentration. The glutathione (GSH)-dependent metabolism of 1,3-D results in significant depletion of GSH at repeated exposure levels of 30 ppm and above. This loss of GSH results in decreased metabolic clearance of this test material, with a concomitant increase of the 1,3-D isomers in circulating blood at exposure concentrations ≥30 ppm. Shifts in the ratio of cis- and trans-1,3-D also support nonlinear toxicokinetics well below 60 ppm. Based on this data, a kinetically derived maximum dose for 1,3-D in mice for repeated exposures should be at or below 30 ppm. These results support non-relevance of 1,3-D-induced benign pulmonary tumorigenicity in mice for human health risk assessment.

Safety of Pseudomonas chlororaphis as a gene source for genetically modified crops.

Genetically modified crops undergo extensive evaluation to characterize their food, feed and environmental safety prior to commercial introduction, using a well-established, science-based assessment framework. One component of the safety assessment includes an evaluation of each introduced trait, including its source organism, for potential adverse pathogenic, toxic and allergenic effects. Several Pseudomonas species have a history of safe use in agriculture and certain species represent a source of genes with insecticidal properties. The ipd072Aa gene from P. chlororaphis encodes the IPD072Aa protein, which confers protection against certain coleopteran pests when expressed in maize plants. P. chlororaphis is ubiquitous in the environment, lacks known toxic or allergenic properties, and has a history of safe use in agriculture and in food and feed crops. This information supports, in part, the safety assessment of potential traits, such as IPD072Aa, that are derived from this source organism.