Bt Brinjal The scope and adequacy of the GEAC environmental risk assessment

54 Bt Brinjal: The GEAC environmental risk assessmentcritical to specify the existing technology carefully or else come double counting may result.Several works allow total or partial farm budgeting to estimate the marginal value of Bt brinjal and Brinjal IPM. Fullcost accounting is done only for IPM in West Bengal (Alam et al. 2006). Total variable costs are evaluated for IPM (Alamet al. 2006 (Gugarat), Baral et al. 2006) and Bt brinjal (Krishna and Qiam 2008). Partial accounting is done here using theinformation presented above.Net return on variable costs is reported in Table 5. The IPM results are the most accurate ones in the table. They arecalculated on-farm, based on what farmers actually do and what farmers actually obtained while growing brinjal. All of theBt values are probably overestimates of the true value of the technology. Krishna and Qiam (2008) base their results on theMahyco MST experiments, which greatly overestimate the value of Bt brinjal (as detailed above). However, Krishna and Qiam(2008) recognise that the yield values reported in the MST experiments are unrealistically high, so they reduce these yield valuesarbitrarily. Specifically, they halved the yield advantage of hybrid Bt brinjal reported in the MST (although they state thatthey use 40%, the actual values reported in their table 2 belies this statement) for use in their economic model. This is morereasonable than the approached used by EC-II and the Dossier to discuss yield advantages of hybrid Bt brinjal. However, asnoted in Table 4 above, this is not enough of a reduction and the predicted yield benefit is still substantially less than that usedby Krishna and Qiam (2008).In addition, Krishna and Qiam (2008) assumed a 75% reduction in insecticide use against BFSB, which is considerablylarger than that estimated above from the LST experiments above and double-counts some of the gains possible using IPM.Thus, Krishna and Qiam (2008) have overestimated the net return for Bt brinjal. Although the actual net returns cannot trulybe known until after Bt brinjal has been approved for commercial use, the results estimated above for the yield benefit from Btbrinjal (Table 4) and the average reduction of 6.5 sprays in large-scale commercial brinjal production can be used to generate amore accurate estimate of net return for Bt brinjal. Even this value is probably overestimated, as discussed above. To estimatenet return, brinjal prices reported in Krishna and Qiam (2008) were used, Rs.462/q in East India and Rs.421/q elsewhere. Inaddition, Rs.500/ha was used as the cost of a single application of insecticide, which is the average value calculated from data inAlam et al. (2006). The net returns for Bt brinjal in West Bengal are placed in brackets because Bt brinjal is not allowed in thisregion (Table 5).