Acephate was first evaluated in 1976, with further reviews of residue aspects in 1979, 1981, 1984, 1990 and 1994. The 1994 JMPR withdrew the previous recommendations for the MRLs for broccoli, Brussels sprouts, head cabbages, cauliflowers, citrus fruits and tomatoes which had been held at Step 7B by the 1989 CCPR (ALINORM 89/24A, para 126). The manufacturer has indicated that information on GAP and residue data would be available to support new MRLs for these commodities. This information was provided to the Meeting, together with information on analytical methods and residues in food in commerce or at consumption.
Analytical methods
Samples from the supervised trials were analysed by GLC and acephate and its metabolite methamidophos were determined individually. Recoveries of both acephate and methamidophos were generally >70%, with limits of determination of 0.01-0.02 mg/kg.
These methods were considered suitable for use in supervised trials and for enforcement.
Storage stability of analytical samples
Extensive storage stability studies were carried out with vegetables, pulses, oilseed, animal products, cereals and grasses. Acephate was shown to be stable in a wide range of macerated or ground commodities at -20°C.
Data validity
In view of the difficulty of determining methamidophos caused by its high polarity, the Meeting did not evaluate trials which lacked data on analytical recoveries or in which recoveries were below 70%, trials without analyses of control samples, or trials with abnormally high control values and for which sample chromatograms were not supplied.
Field trials data
Only residues of acephate are discussed. Residues of methamidophos are discussed in the monograph on that compound.
Citrus fruits. Eight supervised trials, two on Satsuma mandarins, four on Natsudaidai, one on Kabosu (sour orange) and one on Yuzu (lemons or limes) were carried out in Japan. The trials on mandarins and Natsudaidai had already been submitted to the 1994 JMPR. The residues from trials according to GAP (0.025-0.05 kg ai/hl, 30 days PHI) were 0.60 and 1.12 mg/kg in mandarins, 0.13-2.95 mg/kg in Natsudaidai, 0.13 mg/kg in Kabosu and 0.55 mg/kg in Yuzu. A single New Zealand trial on mandarins was according to GAP (0.075 kg ai/hl, 14 days PHI) with a residue of 2.59-3.34 mg/kg (duplicate determinations). In another trial in New Zealand reported in the 1984 JMPR monograph the conditions (0.075 kg ai/hl, 26 days PHI) complied with GAP. The residue was 1.6 mg/kg.
One trial in Greece was reported without information on GAP, but the trial conditions (0.031 kg ai/hl, 20 days PHI) were comparable to Italian GAP (0.024-0.036 kg ai/hl, 21 days PHI). The residue was 0.23 mg/kg. Two Brazilian trials were reported but there was no comparable GAP.
One supervised trial was carried out in Argentina, but there was no comparable GAP and critical information on recoveries was lacking.
Since data on only four adequate additional trials (one Greek, two Japanese and one in New Zealand) were submitted, the Meeting could not recommend an MRL.
Broccoli and cauliflower. The Meeting agreed that the supervised trials on broccoli and cauliflower could be evaluated together because of the similarities in the use patterns and residue behaviour.
One Australian, one Brazilian and two Japanese trials on broccoli complied with national GAP (Australia 0.98 kg ai/ha, 0.098 kg ai/hl, 14 days PHI; Brazil 0.38-0.75 kg ai/ha, 0.075 kg ai/hl, 14 days PHI; Japan 0.05 kg ai/hl, 14 days PHI). In the Australian trial the spray concentration (0.21 kg ai/hl) was higher than the GAP concentration of 0.098 kg ai/hl but the rate in terms of kg ai/ha complied with GAP. Data on the Japanese trials had already been submitted to the 1994 JMPR. The residues were <0.02-0.32 mg/kg, 0.2 mg/kg and 0.07-1.66 mg/kg in the Australian, Brazilian and Japanese trials respectively.
Two French trials (0.73-0.75 kg ai/ha, 0.22-0.25 kg ai/hl, 0-14 days PHI) and two Spanish trials (1.0-1.1 kg ai/ha, 0.091-0.11 kg ai/hl, 0-21 days PHI) on broccoli were reported but information on GAP was not provided. Two Italian trials on broccoli which were submitted to the 1994 JMPR and resubmitted to the present Meeting did not comply with Italian GAP (0.034-0.064 kg ai/hl, 21 days PHI).
One Australian, one Brazilian and two Japanese trials on cauliflower were according to the relevant GAP (Australia 0.98 kg ai/ha, 0.098 kg ai/hl, 3 days PHI; Brazil 0.38-0.75 kg ai/ha, 0.075 kg ai/hl, 14 days PHI; Japan 0.05 kg ai/hl, 14 days PHI). In the Australian trial the spray concentration (0.24 kg ai/hl) again exceeded the GAP concentration but the kg ai/ha rate accorded with GAP. The residues were 0.47-1.37 mg/kg, 0.1 mg/kg and 0.006-0.72 mg/kg in Australia, Brazil and Japan respectively. Five trials in The Netherlands on cauliflower were submitted to the Meeting. One trial carried out in 1972 had been reported to the 1994 JMPR and was resubmitted this year. The trial conditions complied with GAP (0.75 kg ai/ha, 14 days PHI, 6 applications) except that there were only 1-4 applications. However the number of applications seems to have little influence on the residue of acephate. The residues were <0.01-0.12 mg/kg.
Four trials in France on cauliflower (0.50-0.75 kg ai/ha, 0.03-0.42 kg ai/hl and 0-14 days PHI) and one in Germany (0.25 kg ai/ha, 0.025 kg ai/hl and 0-21 days PHI) which had been submitted to the 1994 JMPR were resubmitted, but the trial conditions were not comparable with any relevant GAP.
The residues in one Australian, one Brazilian and 2 Japanese trials on broccoli at maximum GAP were 0.32, 0.2, 0.114 and 1.47 mg/kg respectively. Those in one Australian, one Brazilian, 2 Japanese and 5 Netherlands trials on cauliflower at maximum GAP were 1.37, 0.1, 0.007, 0.655, <0.01, 0.02, 0.03, 0.11 and 0.117 mg/kg respectively.
The residues in broccoli and cauliflower from the 13 trials in rank order were 0.007, <0.01, 0.02, 0.03, 0.1, 0.11, 0.114, 0.117, 0.2, 0.32, 0.655, 1.37 and 1.47 mg/kg. The Meeting estimated a maximum residue level of 2 mg/kg and an STMR level of 0.11 mg/kg for broccoli and cauliflower.
Brussels Sprouts. Two Australian trials complied with the Australian GAP application rate of 0.98 kg ai/ha although the spray concentration of 0.21 kg ai/hl was higher than the GAP concentration (0.098 kg ai/hl). The residues were 0.43-11.5 mg/kg at PHIs of 3 (GAP) to 7 days. One of two American trials complied with American GAP (0.56-1.1 kg ai/ha, 14 days PHI) but the analyzed commodity (trimmed heads) was inappropriate for residue evaluation.
One trial in The Netherlands and three in South Africa according to GAP (0.75 kg ai/ha, 28 days PHI and 0.26-0.38 kg ai/ha, 3 days PHI respectively) were reported to the 1994 JMPR. The residues in The Netherlands were 0.29-0.94 mg/kg at 28 days and in South Africa 0.26-1.3 mg/kg at 7-28 days, and 0.95 and 1.4 mg/kg at 3 days.
The additional data were insufficient to estimate a maximum residue level.
Cabbages. One of two Brazilian trials, three of four French trials and two Japanese trials reflected appropriate GAP (Brazil 0.38-0.75 kg ai/ha, 0.075 kg ai/hl, 14 days PHI; France 0.075 kg ai/hl, 7 days PHI; Japan 0.025-0.05 kg ai/hl, 7 days PHI). In the Brazilian trial the dose rate of 0.26 kg ai/ha was lower than the GAP rate (0.75 kg ai/ha), but the spray concentration (0.075 kg ai/hl) complied with GAP. The data on the Japanese trials had already been submitted to the 1994 JMPR. The residues were <0.05 mg/kg, 0.02-1.25 mg/kg and 0.057-0.66 mg/kg in Brazil, France and Japan respectively.
Data from two German trials were submitted to the Meeting, but GAP was not available from Germany and the trial conditions were not comparable with other European GAP.
Data from one supervised trial in The Netherlands which had been submitted to the 1994 JMPR were resubmitted. The conditions (0.75 kg ai/ha, 14 days PHI, 1 application) accorded with GAP (0.75 ai/ha, 14 days PHI, 6 applications) except in the number of applications. The residues were 0.313-0.331 mg/kg.
Four supervised trials were carried out in New Zealand and the conditions in three of them (0.84 kg ai/ha, 0-7 days PHI; 1.1 kg ai/ha, 10 days PHI; 0.84 kg ai/ha, 16-23 days PHI) complied with GAP (0.75-1.1 kg ai/ha, 7 days PHI). The data were reported in the 1984 JMPR monograph. The residues were 0.8 mg/kg at 7 days, 1.2 mg/kg at 10 days and <0.4 mg/kg at 16 and 23 days respectively.
The residues found in one Brazilian, 3 French and 2 Japanese trials carried out at the maximum conditions complying with GAP were <0.05, 0.05, 0.08, 1.25, 0.07 and 0.578 respectively. Although the trial in The Netherlands was with a single application instead of the six allowed, the residue data could be used for the estimation of an STMR since the number of applications was not considered to be significant. The residue was 0.331 mg/kg. Two of the New Zealand trials also could be used for the estimation of an STMR. The residues were 0.8 and 1.2 mg/kg.
The residues from the 9 trials in rank order were <0.05, 0.05, 0.07, 0.08, 0.331, 0.578, 0.8, 1.2 and 1.25 mg/kg. The Meeting estimated a maximum residue level of 2 mg/kg and an STMR level of 0.33 mg/kg for acephate in cabbages
Tomatoes. GAP in several countries had changed since 1994. Current GAP and additional data on supervised trials were submitted to the Meeting. One Australian, one Brazilian, one Spanish and two Japanese trials reflected GAP (Australia 0.98 kg ai/ha, 0.098 kg ai/hl, 3 days PHI; Brazil 0.38-0.75 kg ai/ha, 0.075 kg ai/hl, 7 days PHI; Japan 0.025-0.05 kg ai/hl, 1 day PHI; Spain 0.038-0.11 kg ai/hl, 14 days PHI). The Australian spray concentration (0.35 kg ai/hl) was higher than the GAP concentration but the dose rate (kg ai/ha) complied with GAP. The data from the Japanese trials had been submitted to the 1994 JMPR and were resubmitted. The residues were 1.5-1.8 mg/kg, <0.05 mg/kg, 0.225-1.03 mg/kg and 0.05 mg/kg in Australia, Brazil, Japan and Spain respectively.
Seventeen trials in France were reported to the Meeting with no information on GAP, but four of them (0.62-0.83 kg ai/ha, 13-15 days PHI, 1-3 applications) complied with Polish GAP (0.75 kg ai/ha, 14 days PHI, 1 application) except in the number of applications which did not appear to influence the residues significantly. The residues were 0.09-0.45 mg/kg. A further ten of the French trials, at 0.03-0.075 kg ai/hl, 13-15 days PHI, were according to Spanish GAP (0.038-0.11 kg ai/hl, 14 days PHI) and showed residues of <0.05-0.95 mg/kg. Data on two South African trials reported in 1994 were resubmitted. The conditions in one trial (0.75 kg ai/ha, 3 days PHI) were according to GAP (0.56-1.5 kg ai/ha, 3 days PHI). The residue was 0.23 mg/kg. Data on ten American and two Canadian trials were submitted, but there was no relevant GAP. The Canadian trials had already been reported to the 1994 Meeting.
One supervised trial in New Zealand reported in the 1994 monograph was at 1.0 kg ai/ha, 0.067 kg ai/hl with 1-16 days PHI, close to the conditions of GAP (0.75 kg ai/ha, 0.075 kg ai/hl, 3 days PHI): the residues were 0.19 and 0.93 mg/kg at 3 and 7 days PHI.
The Meeting decided not to use the data from the Australian trials, only one of which complied with GAP, for the estimation of a maximum residue level because their population was different from that of the others and there were insufficient data.
The residues (mg/kg) in the 9 trials with treatments at maximum levels complying with GAP were 0.05 (Brazil), 0.814 and 0.717 (Japan), 0.05 (Spain), 0.26, 0.29, 0.38 and 0.45 (France), and 0.93 (New Zealand).
The residues from the 9 trials in rank order were <0.05, 0.05, 0.26, 0.29, 0.38, 0.45, 0.717, 0.814 and 0.93 mg/kg. The Meeting estimated a maximum residue level of 1 mg/kg and an STMR level of 0.38 mg/kg for acephate in tomatoes.
Processing studies
Tomatoes. The concentration factors from 3 trials were 1.29, 0.99 and 1.13 for washed fruit and 0.39, 0.63 and 0.50 for canned whole fruit. The mean concentration factors were 1.14 and 0.51 respectively. Washing appears to have no significant effect on the residue. The Meeting estimated an STMR-P of 0.19 mg/kg for canned tomatoes by applying the mean concentration factor to the STMR for tomatoes (0.38 mg/kg). The concentration factor for peeled tomatoes was calculated to be 0.85 from two trials, but the Meeting did not estimate an STMR-P because peeled tomato is only an intermediate product.
Concentration factors for canned juice, bulk paste, canned purée, wet pomace and dry pomace were 0.93, 4.0, 1.79, 0.60 and 1.0 from a single trial and STMR-P levels were calculated as 0.35, 1.52, 0.68, 0.23 and 0.38 respectively.
Cooking studies were carried out on tomatoes, cabbage and broccoli. Boiling for thirty minutes had no measurable effect on the residue levels of acephate.
Monitoring data
A total of 4,357 samples of peaches, nectarines, plums, grapes, tomatoes, lettuce and endive were monitored for acephate in The Netherlands in 1991-1994. The detection frequency ranged from 0.4% for plums and endive to 4.7% for nectarines and the highest mean residue was 0.05 mg/kg in lettuce in 1994.
Market basket survey
A market basket survey for acephate and methamidophos was carried out at 24 locations in the USA in 1984 and 1985. Acephate was found in 6 of 62 collected commodities; the highest residue was 0.72 mg/kg in green sweet peppers.
Farm gate to consumer studies
Farm gate to consumer studies on 5 commodities were carried out in the USA in 1985. Residues of acephate were reduced by 90% from field to supermarket in lettuce, 82% from field to canned product in snap beans, 13% from field to supermarket in bell peppers, 69% from field to processing and freezing in cauliflower and 93% from field to blanching and freezing in Brussels sprouts.
