Table 2.

Worst-case scenario assumptions for the inputs of freely soluble protein, POM, and intact plant material using two models (US EPA standard pond model and EU ditch model)

	US EPA standard pond model	EU ditch model
Assumptions	All plant material from a 10 ha field drains into a 1 ha pond, 2 m deepa 0.3 kg dry weight/plant (dw)b 75,000 plants/hac Bt expression 2–100 mg/kg dry weight plant tissued Bt expression 0.02–74 mg/kg dry weight pollend	Ditch depth of 30 cme 100 g dry weight/m2 plant material depositionf Bt expression 2–100 mg/kg dry weight plant tissued Bt expression 0.02–74 mg/kg dry weight pollend
Total Bt protein calculations	10 ha * 75,000 plants/ha = 750,000 maize plants 750,000 plants * 0.3 kg dw = 225,000 kg dw 225,000 kg dw * 2–100 mg/kg = 450,000–22,500,000 mg protein = 4.5 × 108–225 × 108 μg total protein	100 g/m2 * 2–100 mg/kg dw = 200–10,000 μg total protein
Freely soluble protein (worst-case assumptions)	All protein exists as freely soluble protein 1 ha pond, 2 m deep = 20 × 106 L 4.5 × 108–225 × 108 μg protein/20 × 106 L = 22.5–1,125 μg protein/L	All protein exists as freely soluble protein 200–10,000 μg protein/300 L = 0.67–33 μg protein/L
Particulate organic matter (worst-case assumptions)	Exposed to 0.02–100 mg/kg Bt protein	Exposed to 0.02–100 mg/kg Bt protein
Intact plant material (worst-case assumptions)	Exposed to 2–100 mg/kg Bt protein	Exposed to 2–100 mg/kg Bt protein

^a20,000,000 L; USDA (1982)

^bNguyen and Jehle (2009); 76,700 kg biomass per hectare divided by 75,000 plants per hectare = 1.02 kg fresh weight of biomass per plant during the growing season. Assume 70% moisture; Israelsen et al. (2009)

^c30,000/acre; NASS (2010)

^dNguyen and Jehle (2007, 2009); Raybould et al. (2007)

^e300 L; FOCUS (2003)

^fJensen et al. (2010)