A new tool for the evaluation of crop residue trial data (day-zero-plus decline)

Abstract

An approach is presented for the prediction of pesticide residue concentrations in food and feed commodities produced from foliar-treated crops. It uses limited residue trial data and relies on information on spray retention and decline rates of residues following application. The use of the simple approach is demonstrated for residues of a variety of pesticides and the results compared with data sets evaluated by the Joint FAO/WHO Meeting on Pesticide Residues (JMPR) using expert judgement and also with estimates of high residues obtained using statistical methods. It is proposed that the approach should constitute an additional tool for the risk assessment of pesticide residues; it contributes to the estimation of maximum residue limits (MRLs) and high and median residues, which are needed for risk assessment. The approach should be particularly useful in situations where only a few residue trials are available such as often occurs for minor crops.

Magnitude and decline of pesticide co‐formulant residues in vegetables and fruits: results from field trials compared to estimated values

“…(i) median estimate: SFO decline assuming initial residues based on median day 0‐residue according to Maclachlan and Hamilton 13 and a median DT50 of 5 d (dotted line). (ii) worst case estimate: SFO decline assuming initial residues based on 90th percentile day 0‐residues 13 and an 80th percentile DT50 of 12 d (dashed line). Note: for parsley no day 0‐residues were available and values for lettuce were used as surrogate; for celery only few day 0‐values were available, and no median or 90th percentile was provided, we instead applied the mean of the lower and upper median confidence interval and the highest value, as indicated in Maclachlan and Hamilton, 13 respectively.…”

“…However, all measured residues were well below the respective 90th percentile of scaled day 0-residues, that were 6.9, 70, and 2.6 mg kg -1 for leek, lettuce and apples, respectively, as reported by Maclachlan and Hamilton. 13 With a more simplistic approach, generic day 0-residues (C 0,gen ) can also be estimated assuming that the crop merely acts as a filter for the spray. Field crops are usually sprayed from above.…”

“…Overall, both scaled median day 0-residues (as compiled by Maclachlan and Hamilton 13 ) and calculation using Eq. 1 provided reasonable (worst case) estimates for day 0-residues of all tested substances, as demonstrated by comparison with the measured values (Fig.…”

“…Residues measured directly after application (day 0) and then normalized to an application rate of 1 kg ha -1 (C 0,norm ) for the co-formulants DMDA, docusate, DBNS, SDS, and the active substances spiroxamine and trifloxystrobin, in comparison to day 0-residues as reported in Maclachlan and Hamilton. 13 Leek, leaf and head lettuce, and apple: median values (solid lines). Celery: dotted lines represent the upper and lower 95% confidence interval of the median day 0-residue (no median value provided 13 ).…”

Limitations in the determination of maximum residue limits and highest residues of pesticides: Part I

“…[10] The residues measured in individual supervised trials reflect the expectable residue levels following the practical use of pesticides according to the recommended maximum use patterns. However, the distribution of residues is very uneven within individual trees [17,18] and plots [19,20] and between treated fields [21,22] due to several factors including, for instance, the differences in the actual application rates and techniques, [23,24] spatial structure of canopy and leaf density [25,26] weather conditions [27] and growth dilution. [28] Statistical analysis of field to field variation of residues revealed that it can be described reasonably well with lognormal distribution having relative standard deviation of about 80%.…”