EVALUATION OF EFFECTS ON THE ENVIRONMENT
Mevinphos is a broad-spectrum organophosphate insecticide and acaricide with both contact and systemic activity. It is a mixture of (E)- (>60%) and (Z)- (<25%) geometrical isomers. The mechanism ofpesticidal action is through direct cholinesterase (ChE) inhibition. It is used (except in the USA) to control aphids, mites, grasshoppers, cutworms, leafhoppers, caterpillars and other insects on a variety of vegetable, fruit, and field crops. The available formulations include emulsifiable concentrates, soluble concentrates, ready-to-use liquids, and dusts.
Mevinphos dissipates rapidly in the terrestrial environment. The half-lives of both isomers in soil are less than four days. Biotic degradation is the major means of terrestrial dissipation. The major degradation pathway appears to be the formation of methyl acetoacetate followed by rapid binding to soil and mineralization to carbon dioxide. Under laboratory conditions at 25 °C in the dark the aerobic half-lives of the (E)- and (Z)- isomers were 1.21 and 3.83 hours, respectively.
The hydrolysis half-lives of the (E)- and (Z)- isomers in sterile aqueous buffered solution are related to the pH (pH 9, 2.8 to 7.5 days; pH 5, 50.8 to 84.6 days). (9-demethyl-mevinphos is the major product.
The photolysis half-life in aqueous solution was about 27 days for both isomers.
Mevinphos is potentially very mobile in soils because of its high solubility in water (6 x 105 mg/litre) and low soil partition coefficients (Kads values of 0.392-1.92), but rapid degradation of both isomers in the top 15 cm of soil prevents its being leached further.
Mevinphos is toxic to birds. Acute oral LD50 values range from 1.34 to 4.6 mg ai/kg bw for sharp-tailed grouse, ring-necked pheasants, and mallards. Dietary LC50 values were 236 and 246 ppm ai for Japanese quail and ring-necked pheasants respectively. In reproductive toxicity studies with bobwhite quail and mallards exposed to mevinphos in their diet for 20 to 22 weeks, chronic NOECs were 1.5 ppm ai and <4 ppm ai respectively. The number of viable embryos and the eggshell thickness of bobwhite quail were significantly reduced at 7.1 ppm ai. The body weights of mallard hens were significantly affected at 4 ppm ai.
The oral LD50 value for laboratory rats was 2.2 mg ai/kg bw.
Mevinphos is toxic to a number of insect species. Laboratory-based acute contact and oral LD50 values for honeybees were 0.070 m g/bee and 0.027 m g/bee, respectively. Mevinphos applied at standard field rates was toxic to predaceous mites, parasitic wasps, and predaceous beetles.
Mevinphos is toxic to fish. The 96-h LC50 values for technical mevinphos (60% (E)-isomer and 40% related compounds) were 11.9 m g ai/litre for rainbow trout and 22.5 to 87.0 m g ai/litre for bluegill sunfish. The 96-h LC50 values for the formulated product (30.2-34.6% ai) were 81.4 g ai/litre for bluegill, 41.8 m g ai/litre for rainbow trout, and 1.46 m g ai/litre for Daphnia magna. The 48-h LC50 values of technical material were 0.18 m g ai/litre for Daphnia pulex and 0.42 m g ai/litre for Simocephalus serrulatus. The 96-h LC50 values for other invertebrates include 2.8 to 130 m g ai/litre for Gammarus fasciatus in test-water temperatures of 15-21°C, 5 m g ai/litre for Pteronarcys californica, 13.5 m g ai/litre for Palaemonetes kadiakensis, and 61 m g ai/litre for Asellus brevicaudus.
For estuarine/marine organisms the 96-h LC50 values for the sheepshead minnow were 0.81 mg ai/litre and 0.67 mg ai/litre for total mevinphos and its (E)- isomer respectively, and for mysid shrimp 1.3 m g ai/litre and 1.08 m g ai/litre respectively. The EC50 for the eastern oyster was >1 mg ai/litre, based on a 96-h shell-deposition study.
Chronic studies are not appropriate in view of the rapid degradation of the compound.
Risk Assessment
Terrestrial organisms
Terrestrial organisms may be exposed to mevinphos through consumption of contaminated foods and/or dermal contact with contaminated soil and vegetation.
The risk assessment for foliar sprays is based on comparing dietary LC50 values with predicted environmental concentrations (PECs) of mevinphos on potential avian food items (grass, insects, and seeds). PEC values are based on the Kenaga nomogram as modified by Fletcher et al. Maximum PECs expected immediately following a direct single application of mevinphos at 1.12 kg ai/ha are 240 mg ai/kg for short grasses, 135 mg ai/kg for small insects, and 15 mg ai/kg for seeds.
For birds, TERs, based on comparing the PECs with the lowest LC5g value from avian dietary tests for acute risk, are given in Table 1.
Table 1. Toxicity exposure ratios (TERs) for birds
|
Risk category |
Toxicity value1 |
PEC2 |
TER3 |
Risk classification |
|
Birds, acute |
LC50 = 236 |
240 (short grass) |
1.0 |
very large |
1
Values are for the most sensitive species tested
2 Maximum PECs from a single application of 1.12 kg ai/ha are used for acute risk
3 The TER is calculated as the toxicity value divided by the exposure value (i.e. PEC)
This analysis indicates that mevinphos applied at a typical field application rate of 1.12 kg ai/ha presents "very large" to "present" acute risks to herbivorous (TER = 1.0) and insectivorous (TER = 1.7) birds. Acute risk to granivores is expected to be "low" (TER = 15.7). Wildlife mortality from mevinphos exposure has been reported but most incidents involved misuse. Although mevinphos dissipates rapidly and exposure may be brief, its high acute toxicity clearly poses a danger to exposed wildlife.
The Hazard Ratios for risk to honeybees (application rate of 1120g ai/ha) divided by honeybee LD50 values (m g/bee) were 16,000 and 37,333 for contact and oral exposure, respectively, indicating a high risk to honeybees. Mevinphos should not be applied or allowed to drift on to blooming crops or weeds while bees are actively visiting the treatment area. Mevinphos applied at standard field rates was highly toxic to predaceous mites, parasitic wasps, and predaceous beetles in several studies.
Aquatic organisms
Aquatic organisms may be exposed to mevinphos from surface water run-off and soil erosion, and/or drift from treated sites into water bodies.
For mevinphos, risk is assessed using the Generic Expected Environmental Concentration Program (GENEEC) to estimate aquatic PEC values for use in preliminary risk assessments. Acute risk is assessed using peak PEC values from single and/or multiple applications.
Because chronic toxicity data are not appropriate for mevinphos, the chronic risk to aquatic organisms was not assessed.
The environmental fate values used in the assessment of mevinphos are soil KOC = 1, solubility = 6 x 105 mg/litre, aerobic soil degradation half-life = 1 day, hydrolytic half-life = 16 days, and water photolytic half-life = 27 days.
PEC values after single aerial and ground spray application of mevinphos at rates of 1.12 kg ai/ha and 0.56 kg ai/ha are provided in Table 2.
Table 2. PEC values after single aerial and ground spray applications of mevinphos
|
Application rate' (kg ai/ha) |
Application method |
Peak PEC (m g ai/litre)2 |
|
1.12 |
aerial spray |
16 |
|
|
ground spray |
14 |
|
0.56 |
aerial spray |
8 |
|
|
ground spray |
7 |
1
Application rates are based on the product label for Phosdrin 4 EC (USEPA registration no. 5481-412, accepted 16/5/94)
2 PECs are estimated from the USEPA/OPP GENEEC program
As shown in Table 3, TERs for aquatic invertebrates range from 0.01 to 0.08, which indicate that mevinphos applied at a typical field application rate of 1.12 kg ai/ha presents "very large" acute risks to freshwater and estuarine/marine invertebrates. Acute risk to freshwater fish is classified as "large", based on the TER value of 0.74, but is "low" to estuarine/marine fish (TER =50.6). Although no incidents of fish kills caused by mevinphos have been reported, overspray of freshwaters should be avoided.
Table 3. Risks to aquatic organisms
|
Risk category |
Toxicity value |
PEC1 |
Toxicity: exposure ratio |
Risk classification |
|
Freshwater fish, acute |
11.9 |
16 |
0.74 |
Large |
|
Freshwater invertebrates, acute |
0.18 |
16 |
0.01 |
Very large |
|
Estuarine/marine fish, acute |
810 |
16 |
50.6 |
Low |
|
Estuarine/marine invertebrates, acute |
1.3 |
16 |
0.08 |
Very large |
1
PEC values are calculated from the USEPA/OPP GENEEC screening model; acute exposure is based on peak PEC values for a single aerial application of 1.12 kg ai/ha
2 TER is calculated as the toxicity value divided by the PEC
RESIDUE AND ANALYTICAL ASPECTS
Mevinphos is a systemic and contact organophosphate insecticide and acaricide used to protect a wide range of crops. It was first evaluated toxicologically in 1965 and for residues in 1972. Since the ADI was established before 1976, it is included in the CCPR periodic review programme (ALINORM 89/24A, para 299; Appendix V). The 1991 CCPR scheduled the review for 1996 (ALINORM 91/24A, para 316; Appendix IV, para 11), but the residue review was postponed to 1997 in 1995 (ALINORM 95/24A, Appendix IV).
The Meeting received information on animal and plant metabolism, environmental fate, analytical methods, updated GAP, supervised residue trials on fruits and vegetables, and residues after storage and processing.
Animal metabolism. The absorption, distribution, metabolism and excretion of mevinphos has been studied in rats, cows, goats and hens. Mevinphos is rapidly absorbed, metabolized and excreted.
Rats. Within 24 hours after oral and intravenous administration approximately 76% of the administered [14C] mevinphos was eliminated as 14CO2 and the cumulative excretion in exhaled air and urine accounted for 94% of the total dose in both sexes. Four radioactive peaks were observed in the urine: (E)-mevinphos, (E)-mevinphos acid, demethyl-(E)-mevinphos and unknown.
Cows. Lactating dairy cows were dosed by capsule with unlabelled or 32P-labelled mevinphos at levels up to the equivalent of 20 ppm in the diet for 12 weeks. The milk, fat, liver, kidney, muscle, heart and brain contained less than 0.03 mg/kg mevinphos-equivalent anticholinestease activity at all dose levels throughout the dosing period. The level of organosoluble radioactivity in milk from a cow which received a single dose of [32P] mevinphos (2.0 mg/kg bw) reached a maximum of 0.062 mg/kg mevinphos equivalents 6 hours after administration and decreased to below 0.007 mg/kg at 96-108 hours. The corresponding level in milk from a cow dosed for 7 successive days with [32P] mevinphos at 1.0 mg/kg bw reached approximately 0.05 mg/kg after 6 h and maintained this level for the remainder of the 7 days. Elimination in the faeces and urine accounted for 77% of the [32P] in the single dose and over half of this was excreted in the urine within the first 12 hours. A similar initial excretion was found with the cow dosed for 7 days.
Goats. Lactating dairy goats were treated with [14C] mevinphos for 6 successive days at the equivalent of 18.0 or 2.9 ppm in the diet. Mevinphos was absorbed from the gastrointestinal tract and eliminated in the urine, mainly in the first 8 hours and decreasingly in the next 16 hours. The patterns of urinary elimination were similar for the low and high doses, and the urinary excretion of both doses was apparently complete within 24 hours. The average proportion of the dose excreted within 24 hours was 24.3% of the low dose and 38.7% of the high dose over the 6-day dosing period.
The faeces were a minor route of elimination with averages of 3.38% and 2.55% of the low and high doses respectively within 24 hours. Radioactivity appeared in the first milk collection, which was 8 hours after the first administration, at levels of 0.47 and 3.84 mg/kg mevinphos equivalent from the low and high doses respectively. By the following morning the levels had decreased to 0.21 and 0.52 mg/kg. The daytime/night-time elimination pattern persisted with the repeated dosing and the levels of eliminated radioactivity in the milk seemed to reach plateaus after the 4th dose. The analysis of milk and tissue fractions showed that the radioactivity was associated with normal endogenous components.
Hens. Laying hens were treated by capsule with [14C] mevinphos for 3 successive days at 23 or 2.3 ppm on a daily feed intake basis. The level of radioactivity in the excreta was fairly constant over the three-day collection period and ranged from 23.0% to 29.6% and 38.5% to 43.1% of the daily dose for the birds in the low and high dose groups respectively. The radioactivity in the egg whites accumulated with repeated dosing in both groups, and reached 0.087 and 0.876 mg/kg after the third treatment in the low and high groups respectively. Radioactivity in the egg yolks was detected after the second administration in both dose groups and increased to 0.104 and 0.393 mg/kg in the low and high groups respectively after the third treatment. The analysis of egg yolk and tissue fractions showed that radioactivity was again associated with normal endogenous components.
Plant metabolism. Studies with lettuce, strawberries and turnips showed that mevinphos is metabolized via two pathways in all three plants. A small proportion of mevinphos is converted to mevinphos acid, while the major path involves cleavage of the P-O-C linkage leading to the formation of methyl acetoacetate. Methyl acetoacetate then undergoes reduction to generate methyl (R,S)-3-hydroxybutyrate, which was found conjugated to carbohydrates in plant tissues. The hydroxybutyrate and acetoacetate can undergo hydrolysis to 3-hydroxybutyric acid and acetoacetic acid respectively, which in turn can be conjugated with carbohydrates.
The fate of the phosphorus moiety was not determined because mevinphos was labelled on the carbon attached to the P-O group, but dimethyl phosphate would presumably be formed when the phosphate ester bond is broken.
Degradation in soil. Studies showed that under aerobic conditions mevinphos is degraded rapidly through the formation of methyl acetoacetate, finally to CO2 or fragments which bind to fulvic acid, humic acid or humins.
Field dissipation studies to examine the mobility, degradation and dissipation of mevinphos in soil under field conditions showed that the mobility of both mevinphos isomers is minimal. Essentially no residues were detected in any soil layer one day to two months after application, indicating that the use of mevinphos in sandy soils with low organic matter content, which is the "worst case" for potential groundwater contamination, dose not present any risk. This is mainly due to the rapid degradation of both mevinphos isomers in the top six inches of the soil which prevents any further leaching.
Rotational crop studies were conducted to determine the uptake and nature of the residues in plants following the application of [14C] mevinphos to the soil. Thirty two days after application, lettuce, sugar beet and sorghum were planted and harvested at maturity. All samples contained <0.01 mg/kg mevinphos equivalents.
The trials were carried out with several types of formulation (e.g. 10-50% EC, 50% WP, 24% SL and technical grade active ingredient), but the high solubility of this compound in water makes it unlikely that the type of formulation will significantly affect the residue levels in crops.
In the trials before the 1970s the residues were determined by enzymatic methods which relied on the inhibition of acetylcholinesterase activity and showed only the total inhibitory activity. Since the (E)- isomer is a stronger inhibitor than the (Z)-, and the proportion of the two isomers can be changed by their different dissipation rates in or on crops, the total inhibitory activity does not determine either the individual isomers or their sum. On the other hand, the GLC methods employed in the supervised trials after the 1960s can determine the residues of the two isomers separately, and generally have determination limits of 0.01 mg/kg and recoveries of 80-110% for both the (E)- and (Z)- isomers.
The Meeting agreed not to evaluate the results obtained by enzymatic methods because they do not determine the correct sum of the two isomers and have other limitations. Such methods are also unsuitable for the regulatory determination of mevinphos residues.
The Meeting also decided not to evaluate the results from trials where the duration or conditions of storage of analytical samples were not reported, because the data on the stability of stored analytical samples show that storage conditions are very important for the preservation of the residues of this pesticide and there is no guarantee that residues would be stable for a 10-month period.
However the studies of the stability of mevinphos residues in analytical samples of lettuce, strawberries and turnips which accompanied the plant metabolism studies showed that mevinphos residues were stable in these crops under frozen conditions (~ -20°C) for at least 10 months.
Since the residues of mevinphos in most crops disappear quickly after application the number of applications will not have a significant effect on the residues at the time of harvest. The number of applications was therefore generally disregarded when trial conditions were compared with GAP.
The plant metabolism studies showed that residual mevinphos would be degraded rapidly through the cleavage of the P-O-C linkage, leading to the formation of methyl acetoacetate, and by a minor pathway to (E)-mevinphos acid. Since the level of (E)-mevinphos acid is low in relation to the parent compound however, the Meeting considered that it could be excluded from the definition of the residue.
The Meeting concluded that the present definition of the residue (sum of (E)-mevinphos and (Z)-mevinphos) should be retained both for enforcement and the estimation of dietary intake.
Oranges. Only one supervised trial, carried out in South Africa in 1972, was reported. The trial application (0.04 kg ai/hl) was not comparable with GAP in South Africa (0.015 kg ai/hl, 3 days PHI), and no other information on GAP for citrus fruits was submitted.
There were insufficient data to estimate a maximum residue level for oranges or citrus fruit, and the Meeting recommended the withdrawal of the CXL for citrus fruits (0.2 mg/kg).
Apples and pears. Four supervised trials on apples were carried out in France (1969) and five in the UK (1971 and 1972). Two UK trials at an application rate of 0.25 kg ai/ha complied with French GAP (0.25-0.75 kg ai/ha, 0.05 kg ai/hl, 7 days PHI) and were comparable with Austrian GAP (0.096-0.19 kg ai/ha, 0.0096-0.019 kg ai/hl, 14 days PHI). Two other UK and two French trials at application rates of 0.5 kg ai/ha were also according to French GAP. The other trials were at a higher rate than any GAP reported to the Meeting.
Two supervised trials on pears were carried out in France in 1969, but critical information such as sample storage conditions was not reported.
The Meeting could not estimate a maximum residue level for apples or pears, as there were too few appropriate trials, and recommended the withdrawal of the existing CXLs for apple (0.5 mg/kg) and pear (0.2 mg/kg).
Apricots. Only one supervised trial carried out in the USA in 1958 was reported, with no comparable GAP. The trial samples were analysed by an enzymatic method, and the sample storage period was not reported. The Meeting could not estimate a maximum residue level and recommended the withdrawal of the existing CXL for apricot (0.2 mg/kg).
Cherries. Fourteen supervised trials were carried out in France (4 in 1970 and 4 in 1971), Germany (3 in 1974, 1 in 1982 and 1 in 1983) and the USA (1 in 1958).
The three German trials in 1974 with application at 0.025 kg ai/hl and one in 1983 at 0.24 kg ai/ha and 0.024 kg ai/hl could be compared with Austrian GAP (0.096-0.19 kg ai/ha, 0.0096-0.019 kg ai/hl, 14 days PHI). The 1982 trial was at the same rate as in 1983, but sampling was only up to 10 days whereas the GAP PHI is 14 days. The Meeting concluded that in view of the rapid decline of this compound on crops a PHI of 10 days was not comparable with the GAP PHI. The residues in the other trials were <0.02-0.09 mg/kg at PHIs of 14-28 days.
The other nine trials were not comparable with any reported GAP. In the US trial the samples were analysed by an enzymatic method and the sample storage period was not reported.
The Meeting could not estimate a maximum residue level from the few adequate trials, and recommended the withdrawal of the CXL for cherries (1 mg/kg).
Peaches. Two supervised trials in France in 1969 could not be evaluated because critical information on such items as sample storage conditions was not reported. Three supervised trials in Germany (1974) at an application rate of 0.025 kg ai/hl were comparable with Austrian GAP (0.0096-0.019 kg ai/hl, 14 days PHI). The residues were <0.02-0.03 mg/kg at 14-21 days. A US trial in 1957 was not comparable with any reported GAP, the samples were analysed by an enzymatic method and the sample storage period was not reported.
There were too few satisfactory trials to estimate a maximum residue level and the Meeting recommended the withdrawal of the CXL for peach (0.5 mg/kg).
Currants. Ten supervised trials were carried out in Germany (1974 and 1975) and the UK (1971) but no information on comparable GAP was reported. The Meeting could not estimate a maximum residue level.
Grapes. Four French trials in 1969 could not be evaluated because sample storage conditions were not reported.
One French trial in 1971 with an application rate of 0.15 kg ai/ha complied with French GAP (0.05-0.25 kg ai/ha, 0.05 kg ai/hl, 7 days PHI). The residue was <0.02 mg/kg at 5 days. Two South African trials and one US trial were not comparable with any reported GAP and the US samples were analysed by an enzymatic method.
The Meeting could not estimate a maximum residue level and recommended the withdrawal of the CXL for grapes (0.5 mg/kg).
Strawberries. Seven supervised trials were carried out in Portugal (1971) and the USA (1957 and 1962), but no comparable GAP was reported. The US samples were analysed by an enzymatic method, and the sample storage period was not reported in the 1957 trial.
The Meeting recommended the withdrawal of the CXL for strawberry (1 mg/kg).
Broccoli. Two supervised trials were carried out in the USA in 1965 but no comparable GAP was reported and the analyses were by an enzymatic method.
The Meeting recommended the withdrawal of the CXL for broccoli (1 mg/kg).
Cauliflower. Eight supervised trials were carried out in France (1969), Germany (1974), and the USA (1972) but no comparable GAP was reported. Sample storage conditions were not reported in the French trials.
The Meeting could not estimate a maximum residue level and recommended the withdrawal of the CXL for cauliflower (1 mg/kg).
Brussels sprouts. Only one supervised trial, which was carried out in South Africa in 1980, was reported. This conformed to South African GAP (Brassica vegetables: 0.11 kg ai/ha, 0.011 kg ai/hl, 4 days PHI), with residues of <0.04 mg/kg at 4-16 days, but was inadequate to estimate a maximum residue level.
The Meeting recommended the withdrawal of the CXL for Brussels sprouts (1 mg/kg).
Head cabbages. Six supervised trials were carried out in Germany (1975, 1982 and 1983), and 14 in the UK (1960, 1970 and 1972).
In the six UK trials in 1960 the samples were analysed by an enzymatic method.
The conditions in three German trials in 1975 with applications at 0.025 kg ai/hl were comparable with French GAP (0.35 kg ai/ha, 0.035 kg ai/hl, 7 days PHI). The highest residues at 7-21 days were 0.02 and 0.03 (2) mg/kg.
Three German trials in 1982 and 1983 were at application rates of 0.43 kg ai/ha and 0.072 kg ai/hl. This is higher than GAP in Austria (0.096 kg ai/ha, 0.0096 kg ai/hl, 14 days PHI), France (0.35 kg ai/ha, 0.035 kg ai/hl, 7 days PHI) and The Netherlands (Brassica vegetables: 0.015-0.11 kg ai/ha, 0.007-0.011 kg ai/hl, 7 days PHI), but the results could be used for residue evaluation because all three residues were below the limit of determination of 0.02 mg/kg at 7-10 days at, effectively, maximum GAP conditions.
The application rate of 0.25 kg ai/ha in five UK trials in 1970 and 1972 was comparable to the GAP rate in France, but in four of them samples were taken only up to 5 days and residues, were detected in two. The other three results could be used because the residues were all below the LOD of 0.02 mg/kg.
In three other UK trials in 1970 and 1972 the application rate of 0.5 kg ai/ha was higher than GAP in Austria, France, and The Netherlands, but two results could be used for evaluation because the residues were <0.02 mg/kg at 7-8 days, below the limit of determination.
The Meeting could use six German and five UK trials to estimate a maximum residue level and an STMR. The residues from the eleven trials in rank order were <0.02 (8), 0.02 and 0.03 (2) mg/kg.
The Meeting estimated a maximum residue level of 0.05 mg/kg, to replace the existing CXL of 1 mg/kg, and an STMR level of 0.02 mg/kg for head cabbages.
Kale. Nine supervised trials were carried out in Germany in 1974, 1982 and 1983 but no comparable GAP was reported, so the Meeting could not estimate a maximum residue level and recommended the withdrawal of the existing CXL (1 mg/kg).
Chinese kale. Two supervised trials were reported by the government of Thailand and one was in accord with the national GAP (Brassica vegetables: 0.36-0.48 kg ai/ha, 0.036-0.048 kg ai/hl, 3 days PHI). One trial was not enough to estimate a maximum residue level.
Cucumbers. Three outdoor German trials at 0.025 kg ai/hl were comparable with French GAP (0.35 kg ai/ha, 0.035 kg ai/hl, 7 days PHI) and all the residues were <0.02 mg/kg.
Four outdoor trials in The Netherlands were not comparable with any reported GAP and sample storage conditions were not reported.
Three German glasshouse trials in 1974 at 0.025 kg ai/hl and two in 1983 at 0.29 kg ai/ha and 0.032 kg ai/hl did not accord with any reported GAP. One German glasshouse trial in 1982 (0.14 kg ai/ha, 0.023 kg ai/hl) complied with GAP in The Netherlands (Fruiting vegetables in glasshouse: 0.073-0.22 kg ai/ha, 0.007-0.015 kg ai/hl, 3 days PHI). The residues were 0.02-0.04 mg/kg at 3-7 days.
There were too few trials to estimate a maximum residue level and the Meeting recommended the withdrawal of the CXL for cucumber (0.2 mg/kg).
Melons and watermelons. Three supervised trials on melons and one on watermelons were reported but no information on comparable GAP was available. The samples were analysed by an enzymatic method and two trials lacked information on the conditions or duration of sample storage.
No maximum residue level could be estimated and the Meeting recommended the withdrawal of the CXL for melons except watermelon (0.05 mg/kg).
Tomatoes. Four outdoor trials were carried out in Belgium (1969), two in France (1969) and three in Germany (1975). Two glasshouse trials were conducted in Belgium (1970), four in Germany (1975 and 1982) and two in The Netherlands (1970).
The three German outdoor trials (0.025 kg ai/hl) could be compared to French GAP (0.35 kg ai/ha, 0.035 kg ai/hl, 7 days PHI); all three residues were <0.02 mg/kg at 7-10 days. In the other six outdoor trials the sample storage conditions were not reported.
Three of the four German glasshouse trials were not comparable with any reported GAP. The other (0.14 kg ai/ha, 0.023 kg ai/hl) corresponded to GAP in The Netherlands (Fruiting vegetables in glasshouse: 0.073-0.22 kg ai/ha, 0.007-0.0,15 kg/I, 3 days PHI) and Belgium and Luxembourg (0.12-0.36 kg ai/ha, 0.012-0.018 kg ai/hl, 7-14 days PHI). The residues were <0.02 mg/kg at 3-7 days.
The Meeting could not estimate a maximum residue level owing to the small number of trials, and recommended withdrawal of the existing CXL for tomato (0.2 mg/kg).
Baby corn. Two supervised trials were reported by the government of Thailand and one, with application at 0.14 kg ai/ha, was close to the national GAP (Sweet corn: 0.06-0.12 kg ai/ha, 0.012-0.024 kg ai/hl, 3 days PHI). No residue was detectable. One trial was not enough to estimate a maximum residue level.
Lettuce. Nineteen outdoor trials were carried out in Belgium (4), France (4), Germany (6), The Netherlands (2), Spain (1) and the UK (2), and 22 glasshouse trials in Belgium (8), Germany (4), The Netherlands (6), and the USA (4).
There was no information on whether the crops were head or leaf lettuce, and the sample storage conditions were not reported in the Belgian or Dutch outdoor trials or in two of the Dutch glasshouse trials. In the US trials (in 1965) the samples were analysed by an enzymatic method.
The manufacturer informed the Meeting that data on new trials to cover both head and leaf lettuce would be submitted to a future Meeting.
The Meeting could not estimate a maximum residue level because essential information was not available and recommended the withdrawal of the CXL for head lettuce (0.5 mg/kg).
Spinach. Three supervised trials were carried out in Germany (1974), three in the UK (1958) and one each in Belgium (1972 under glass) and South Africa (1980).
The Belgian trial was at an application rate of 0.1 kg ai/hl, but no comparable GAP was reported. The samples in the UK trials were analysed by an enzymatic method. The trial in South Africa at an application rate of 0.11 kg ai/ha with 0.022 kg ai/hl did not comply with South African GAP (0.11 kg ai/ha, 0.011 kg ai/hl, 3 days PHI).
In the German trials the application rate of 0.025 kg ai/hl was comparable to French GAP (0.35 kg ai/ha, 0.035 kg ai/hl, 7 days PHI). The residues at 7 days were 0.03, 0.05 and 0.07 mg/kg.
The Meeting could not estimate a maximum residue level as there were too few trials, and recommended the withdrawal of the CXL for spinach (0.5 mg/kg).
Carrots, celeriac, potatoes and turnips. Three German trials on carrots were at an application concentration of 0.025 kg ai/hl. This is higher than GAP in The Netherlands (root and tuber vegetables: 0.015-0.15 kg ai/ha, 0.007-0.015 kg ai/hl, 7 days PHI), but the results could be used for residue evaluation because all three residues were below the limit of determination of 0.02 mg/kg at 7-14 days. A single US trial was not comparable to any reported GAP and the residues were determined by an enzymatic method.
Three supervised trials were carried out on celeriac in Germany in 1983 at an application rate of 0.16 kg ai/ha at 0.027 kg ai/hl. The spray concentration was higher than GAP in The Netherlands but again all three residues were <0.02 mg/kg at 7 days.
Supervised trials were carried out on turnips and potatoes in the USA in 1956 but no comparable GAP was reported and the residues were determined by an enzymatic method.
The Meeting could not estimate maximum residue levels for carrots, celeriac, potatoes or turnips with so few trials and recommended the withdrawal of the existing CXLs for carrot, potato and garden turnip (all 0.1 mg/kg).
Leeks. Five supervised trials were carried out in Germany (1974, 1982 and 1983) at application rates of 0.025 kg ai/hl or 0.14-0.16 kg ai/ha with 0.023-0.027 kg ai/hl. These rates are higher than GAP in The Netherlands for stem vegetables (including leeks) of 0.015-0.15 kg ai/ha, 0.007-0.015 kg ai/hl, 7 days PHI, but all five residues were below the limit of determination, <0.02 mg/kg, at 7-14 days.
The Meeting estimated a maximum residue level of 0.02* mg/kg and an STMR of 0.02 mg/kg.
Bulb onions. Only one supervised trial, carried out in the USA in 1956, was reported. There was no comparable GAP, and residues were determined by an enzymatic method.
The Meeting could not estimate a maximum residue level and recommended the withdrawal of the CXL for bulb onions (0.1 mg/kg).
Common beans. Eleven outdoor trials were carried out in Germany (3 in 1974) and the UK (6 in 1960 and 2 in 1971) and four glasshouse trials in Germany in 1974 and 1982, but the samples in the 1960 UK trials were analysed by an enzymatic method.
The three outdoor trials in Germany in 1974 were at an application concentration of 0.025 kg ai/hl. This was higher than GAP in The Netherlands (Legume vegetables: 0.015-0.15 kg ai/ha, 0.007-0.015 kg ai/hl, 7 days PHI) but two of the trials could be used for residue evaluation because all the residues at 7-14 days were <0.02 mg/kg, below the limit of determination.
The two outdoor trials in the UK in 1971 were at application rates of 0.25 and 0.5 kg ai/ha. The lower rate was comparable to French GAP (0.35 kg ai/ha, 0.035 kg ai/hl, 7 days PHI) but exceeded GAP in The Netherlands, and the higher rate exceeded GAP in both countries. The results of both trials could again be evaluated however because the residues were below the limit of determination, <0.02 mg/kg, at 2-7 days. This also applied to two of the three glasshouse trials in Germany in 1974 where the application concentration of 0.025 kg ai/hl was higher than GAP in The Netherlands (Legume vegetables in glasshouse: 0.036-0.15 kg ai/ha, 0.007-0.015 kg ai/hl, 7 days PHI for July).
A glasshouse trial in Germany in 1982 was at a rate of 0.14 kg ai/ha with 0.023 kg ai/hl. The kg ai/ha rate accorded with GAP in The Netherlands and the residue at 7 days was 0.03 mg/kg.
The Meeting agreed to combine the residue data from the outdoor and glasshouse trials because no difference was observed in the residue populations. The residues from the seven relevant trials in rank order were <0.02 (6) and 0.03 mg/kg.
The Meeting estimated a maximum residue level of 0.05 mg/kg and an STMR of 0.02 mg/kg for common beans. The maximum residue level is recommended as an MRL to replace the existing CXL (0.1 mg/kg).
Peas. Four supervised trials were carried out in South Africa (1969) and the UK (1957), but all the samples were analysed by enzymatic methods.
The Meeting could not estimate a maximum residue level and recommended the withdrawal of the CXL for peas (0.1 mg/kg).
Soya beans and peanuts. A supervised trial on soya beans in Brazil and two trials on peanuts in Brazil and South Africa were reported to the Meeting, but relevant GAP was not available.
The Meeting could not estimate maximum residue levels.
Sugar beet. Five supervised trials were carried out in France in 1975 at application rates of 0.24, 0.25 and 0.35 kg ai/ha, but the PHIs (91-98 days) were not comparable with any reported GAP.
In two supervised trials in Germany the application concentration of 0.025 kg ai/hl complied with Austrian GAP (0.12 kg ai/ha, 0.02-0.03 kg ai/hl, 14 days PHI). The residues at 7-14 days were <0.02 mg/kg (4 results) in the roots and <0.02 (2), 0.03 and 0.04 mg/kg in the leaves.
The Meeting could not estimate a maximum residue level for sugar beet or for sugar beet leaves or tops.
Storage
Storage studies were carried out on peaches, strawberries, red cabbage, broccoli, lettuce and spinach at ambient temperature.
Because the number of trials was limited the decline profile of mevinphos residues in or on crops was not clear, but the data showed that the residues declined quickly except in peaches. Half-lives of 29, 3.7-3.9, 3.4, 1.3, 3.4-6.3 and 2.2 days were calculated for peaches, strawberries, red cabbage, broccoli, lettuce and spinach respectively on the assumption that the logarithm of the residue value decreased linearly with time.
Processing
Household. Boiling, washing, and/or peeling studies were carried out on red cabbage, broccoli, cauliflower, spinach and apples but the samples from two of the three broccoli trials and the two cauliflower trials were analysed by enzymatic methods and were not evaluated.
The processing factors were 0.27 and 0.67 for washing cabbage, 0.18 for boiling cabbage, 0.33 for boiling broccoli, 0.26-0.32 for boiling spinach, 0.71-0.95 for peeling apples and 0.53-0.75 for cooking peeled apples.
Industrial. Processing factors for grapes were 0.87 to fresh juice, 1.15 to wet pomace, 0.33 to dry pomace, 0.25 to raisins and 22.2 to raisin waste. Evidently more mevinphos than moisture is lost during drying.
