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Table 3 Data sources and assumptions required to quantify the impact of GE crops on pesticide use in the U.S., 1996-2011

From: Impacts of genetically engineered crops on pesticide use in the U.S. -- the first sixteen years

Parameter Source Supplemental table impacted Basis and explanation
National Pesticide Use per Acre/Hectare NASS-USDA 1, 2 Best publicly available estimates of annual per acre herbicide and insecticide use
Annual Gaps in NASS Survey Data by Crop Interpolated 1, 2 Changes in total herbicide, glyphosate, and insecticide use occur linearly/annum when there are gaps in NASS pesticide use surveys
Annual Application Rates of "Other Herbicides on HR Hectares" (See Table 4) 8, 9, 10 Trends by crop on HR acres track changes in total herbicide use, as reported by NASS; changes from year to year are gradual
Bt Cry Proteins Produced by Bt Corn and Cotton Plants Projected (see text, Additional files) 20-25 Trait-specific expression levels by tissue taken from documents submitted by technology developers; used to quantify volume of each Bt endotoxin produced by plants per acre/hectare based on typical planting density
Insecticide Use on Bt Corn (Details in Table 4) 11, 12 Insecticide displacement as a result of planting Bt corn corrected for hectares not likely to have been treated in the absence of Bt corn cultivars
Insecticide Use on Bt Cotton NASS-USDA 13 Budworm/bollworm control insecticide displacement on hectares planted to Bt cotton is 100%