Chlorfenvinphos is a contact and soil-applied organophosphorus insecticide available as granules, EC or WP sprays and seed-treatment formulations. It is used for the control of various pests, including wheat bulb fly, cabbage root fly and carrot fly, on a range of crops.
Chlorfenvinphos is present in the form of two configurational isomers and is liquid at 25°C. Data on physico-chemical properties were provided only for the technical material. The data on the solubility of chlorfenvinphos in water, fat and organic solvents and the octanol-water partition coefficient, were not supported by full study reports and have therefore not been included in the evaluation.
In briefly reported studies on humans, rats and dogs, chlorfenvinphos was extensively metabolized, and a number of metabolites were identified.
A number of briefly reported metabolism studies on ruminants were submitted in which cows were treated by injection or spraying, but none in which cattle were treated by oral ingestion. A number of metabolites were identified and a metabolic pathway proposed in which it was postulated that incorporation of some of the metabolites took place by conjugation with glucuronide. Most of the radioactive residue was found in the omental or renal fat, with little or no residue in the liver, kidney or other tissues even at high doses. However, these studies were old and briefly reported with limited experimental detail. The Meeting considered that new data on metabolism in lactating ruminants and/or laying poultry to meet modem standards are required if significant residues occur in relevant feed items. In addition, data on the ruminant metabolism of chlorfenvinphos applied externally are required to support the approved use for dipping in Australia.
In plants two main investigations were conducted, one with foliar applications to potatoes, cabbages and maize and the other with soil applications to cabbages, carrots and onions. Significant residues of parent chlorfenvinphos remained in crops sampled several weeks after treatment. The main metabolite from foliar applications was the conjugate of 1-(2,4-dichlorophenyl)ethanol. Traces of desethyl-chlorfenvinphos were also detected. After soil applications the metabolite 2,4-dichloroacetophenone was identified together with some polar unextractable material. These metabolism studies were old and briefly reported with limited experimental detail: the full metabolic pathway in plants was not elucidated. Although the data appeared to show that chlorfenvinphos was the major component of the residue the Meeting considered that new data on metabolism and translocation in plants according to modem standards are required to confirm this.
In a laboratory study of degradation in soil a number of products were identified and a degradation pathway was proposed. Chlorfenvinphos was the major single compound identified although 1-(2,4-dichlorophenyl)ethanol, the sodium salt of desethyl-chlorfenvinphos, and 2,4-dichloroacetophenone were present in significant concentrations. Degradation was slower in organic than in mineral soils. In the field, half-lives of chlorfenvinphos were 14-84 days in mineral soils and more than 150 days in peat soil.
The analysis of crop and soil samples for chlorfenvinphos and its metabolites was based on GLC with FP, EC or NP detection. The reported limits of determination were 0.01-0.05 mg/kg. Only limited data on validation of the methods were presented.
A definition of the residue as "chlorfenvinphos, sum of (E)- and (Z)- isomers" was recommended, but the Meeting agreed that the definition might have to be reconsidered when new data on plant and animal metabolism have been reviewed.
The information on GAP supplied by the manufacturer was incomplete. No copies of the product labels were submitted, only summary sheets.
Reports of residue trials on leeks, onions, head cabbage, Savoy cabbage, cauliflower, mushrooms, kale, carrots, parsley root, parsnips, potatoes, swedes, sweet potatoes, radishes, turnips, celery, rape seed, parsley, maize, and wheat were submitted, but as no GAP was reported for parsley root or sweet potatoes the Meeting could not estimate maximum residue levels for these commodities. No residue trials were reported on several crops for which GAP and/or CXLs exist, and the Meeting recommended withdrawal of the unsupported CXLs.
Many of the trials were very old with no detailed study reports. Details such as the method of analysis, the duration of sample storage, analytical recoveries and plot size were lacking. The Meeting agreed that such data were inadequate for the estimation of maximum residue levels. In many other trials the duration of sample storage before analysis was not reported and the Meeting agreed that although the data could be used to estimate maximum residue levels, such levels could not be recommended as MRLs because data on the stability of residues in stored analytical samples of representative substrates were required to confirm the validity of the results.
Onions. GAP was reported for several countries. A number of residue trials on bulb onions together with one on spring onions were reported. Four French trials with residues of <0.02 mg/kg complied with the granular application rate in France, but a PHI of 15 days was reported by the manufacturer as French GAP, whereas the PHIs in the trials were 133-182 days. One German trial according to GAP for pre-planting spray treatment in Belgium and The Netherlands gave residues below 0.02 mg/kg after 175 days (shorter PHIs were not considered to accord with GAP). A further five German trials were considered to comply with GAP for pre-planting granular treatments in Belgium, Denmark, Germany and The Netherlands: all residues were below the LOD (<0.02 mg/kg). Two replicated Japanese trials reflected Japanese foliar GAP (which has a low application rate), with residues of <0.02 mg/kg 7-8 days after treatment. The only measurable parent residues reported were from the higher application rate of 4.8 kg ai/ha in a German spray trial (0.04 mg/kg, at a 60-day PHI) and in one UK trial (0.07 mg/kg, PHI of 61 days) which was very old and poorly described with no detailed study report. These trials were not comparable with any reported GAP.
The Meeting estimated an STMR of 0.02 mg/kg and a maximum residue level of 0.02* mg/kg. These estimates were based partly on trials which lacked information on the duration of sample storage.
Cabbage. Registered uses on head cabbage were reported in Belgium, Denmark, France, Germany, Ireland, Italy, Japan, The Netherlands, Sweden, Switzerland, and the UK, and on Savoy cabbage in Germany and The Netherlands. Residue trials on head cabbage were reported from the UK, Germany, the USA and India, and on Savoy cabbage from Germany. Seven German trials on head cabbage and three on Savoy cabbage complied with GAP for pre-planting soil treatments at 0.1 kg ai/m2. Six further trials on head cabbage reflected the German granular seedbed GAP of 2 g/100 plants and three trials on Savoy cabbage the German 2 kg ai/ha GAP. All residues in all these trials were below 0.02 mg/kg. The German granular treatment at 0.1 g/plant (in some cases in combination with an earlier pre-planting soil treatment at 0.1 kg ai/m2) was represented by four acceptable trials on Savoy cabbage and one on head cabbage with residues of 0.02, 0.03, 0.15, 0.3 and 0.9 mg/kg. One UK trial complied with UK Gap for pre-emergence sprays but was very old and poorly reported without details. No trials were considered comparable with the GAP for foliar treatments reported in several countries, which have shorter PHIs. The Meeting agreed that there were insufficient data to estimate a maximum residue level on the basis of the German 0.1 g/plant granular treatment. However in view of the many trials conforming to German GAP for pre-planting and seedbed applications, all with residues below 0.02 mg/kg, the Meeting estimated an STMR of 0.02 mg/kg and a maximum residue level of 0.02* mg/kg. The trials on which these estimates were based included some which lacked information on the duration of sample storage and others for which this information was not clear to the reviewer because the study was not reported in the working language of the Meeting.
Cauliflower. GAP was reported for Germany, Ireland, The Netherlands and the UK. Residue trials were carried out in Germany, India, the USA and the UK. There were three German trials according to each of three different German GAP treatments: 2 g/100 plants nursery granular, the 0.1 g/plant single bed treatment and the 2 kg ai/ha granular "spreading" application. The UK and Dutch spray treatment (ca. 4-5 kg ai/ha) at the time of drilling or transplanting was reflected by four German trials. All the residues in these trials were <0.02 mg/kg.
The Meeting estimated an STMR of 0.02 mg/kg and a maximum residue level of 0.02* mg/kg. Again some of the trials had no information on the duration of sample storage and others were not reported in English.
Mushrooms. GAP was reported only for the UK as either compost or casing incorporation. Only one trial was available which was poorly described with no detailed study report. There were insufficient data to estimate an STMR or maximum residue level and the Meeting recommended that the existing CXL of 0.05 mg/kg should be withdrawn.
Kale. There are registered uses in Germany, The Netherlands, Portugal and Spain, but residue trials were available only from Germany. Five trials were according to the Dutch GAP for spray treatments at planting or before sowing. Residues were all <0.02 mg/kg. In one of these trials the residue of dichlorophenylethanol was 0.07 mg/kg. Three further trials complied with the German granular single plant treatment, and in two others this treatment was combined with soil treatment according to German GAP. Residues in these trials were 0.02 (2), 0.02, 0.07 and 0.09 mg/kg. There were insufficient data to estimate an STMR or maximum residue level.
Carrots. GAP was reported for Belgium, Denmark, France, Germany, Ireland, Italy, Luxembourg, The Netherlands, Switzerland and the UK. Residue trials were available from Canada, France, Germany, The Netherlands, South Africa, Spain, Sweden, Switzerland, Trinidad and the UK. In addition the UK government provided data on residues in overwintered commercial carrots whose treatment history had been recorded. The highest residues resulted from post-planting EC or WP sprays at c. 4 kg ai/ha which corresponds to GAP in The Netherlands and France. Similar treatments at c. 2.5 kg ai/ha are GAP in Ireland and the UK. The PHIs reported for these countries ranged between 21 and 60 days which reflects second generation carrot fly control. French GAP was also reported to include an EC spray at 5 kg ai/ha with a PHI of 15 days, but the Meeting was informed that the use in practice was at the time of sowing. Several trials in France, Germany and The Netherlands complied with the higher rate GAP, with residues of 0.02, 0.05, 0.08, 0.12, 0.14, 0.2(3), 0.22. 0.3, 0.37, 0.45, 0.9, 1.2, 1.8, 2.0, and 3.8 mg/kg. In the overwintered commercial carrots treated in accordance with UK GAP the residues were 0.02-1.6 mg/kg.
The Meeting estimated an STMR of 0.22 mg/kg and a maximum residue level of 5 mg/kg. This estimation was based in part on trials for which no information on the duration of sample storage was reported.
Parsnips. GAP was reported for The Netherlands and the UK. The UK provided government-generated data on residues in overwintered commercial parsnips of known treatment history. Two residues were from treatments according to UK GAP (2.35 kg ai/ha). The residues were 0.14 and 0.16 mg/kg. The estimates of the STMR and maximum residue level for carrots are based on the post-planting EC or WP spray at 4 kg ai/ha reported as GAP in The Netherlands. Since GAP for parsnips in The Netherlands is the same as for carrots the Meeting agreed that the data on carrots could be used to estimate maximum and mean residue levels for parsnip by extrapolation.
The Meeting estimated an STMR of 0.22 mg/kg and a maximum residue level of 5 mg/kg:
The estimates were based in part on trials for which there was no information on the duration of sample storage.
Potatoes. There are registered uses in The Netherlands and Poland. Residue trials were carried out in the UK, Spain, Australia and Poland, but they were very old and poorly reported with few details. There were insufficient data to estimate an STMR or maximum residue level and the Meeting recommended that the existing CXL of 0.05 mg/kg should be withdrawn.
Radishes. GAP was reported for Germany, The Netherlands and the UK. Residue trials were in Germany and Switzerland. Several of the trials were very old and none were reported in detail. In addition the UK provided government-generated data on residues (four results) in overwintered commercial radishes of known treatment history. The residues following applications close to GAP were all <0.1 mg/kg. There were insufficient data to estimate an STMR or maximum residue level and? the Meeting recommended that the existing CXL of 0.1 mg/kg should be withdrawn.
Swedes and turnips. GAP for swedes and turnips was reported for The Netherlands and the UK. One field trial in the UK on swedes and three in the UK or USA on turnips were reported analytical recovery was high (>120%) in the trial on swedes and the others were old and poorly described with no detailed study reports. The Meeting also received reports of six German trials on? swedes or turnips in which the commodity was described as "turnip cabbage". This was ah error in translation from the original German and the correct description was "swede/turnip". These trials did not comply with UK or Netherlands GAP.
There were insufficient data to estimate ah STMR or maximum residue level and the Meeting recommended that the existing CXLs of 0.05 mg/kg should be withdrawn.
Celery. There is a registered use in The Netherlands. One group of residue trials was reported, at a unspecified location. It was poorly described, with no detailed study report
There were insufficient data to estimate an STMR or maximum residue level and the Meeting recommended that the existing CXL of 0.4 mg/kg should be withdrawn.
Rape seed. GAP for rape was reported for Austria, Germany, The Netherlands and Poland. Several field trials were carried out in France and Germany. Six German trials complied with German GAP for EC spray. Residues in all the trials were 0.02 mg/kg. There were no trials with the broadcast application of granules at 3 kg ai/ha used in The Netherlands, although in two French trials with an application rate of 1kg ai/ha residues were <0.02 mg/kg.
The Meeting estimated an STMR of 0.02 mg/kg and a maximum residue level of 0.02* mg/kg. The estimates were based on trials without information on the duration of sample storage.
Parsley. There are registered uses in The Netherlands and the UK with WP or EC spray applications. Summarized reports of residue trials were available from Germany, but all the trials were with granular formulation whereas the reported GAP applications are by spraying.
There were insufficient data to estimate an STMR or maximum residue level.
Maize. GAP was reported for The Netherlands. Residue trials were carried out in France but were very old and poorly described with no detailed study reports.
There were insufficient data to estimate an STMR or maximum residue level and the Meeting recommended that the existing CXL of 0.05 mg/kg should be withdrawn.
Wheat. There are registered uses in the UK. Two residue trials in the UK were very old and poorly reported with inadequate detail.
There were insufficient data to estimate an STMR or maximum residue level and the Meeting recommended that the existing CXL of 0.05 mg/kg should be withdrawn.
Lettuce and lamb's lettuce as rotational crops. Trials were carried out in Germany, but the data were submitted in JMPR summary format only with no accompanying study reports.
The lettuce or lamb's lettuce was planted 1-4 months after the treatment of radishes as the primary crop at 4 kg ai/ha. The dates of harvest of the radish crop and the residue levels in the soil were not recorded. The residues in lamb's lettuce at harvest were <0.04 (4) and 0.19 mg/kg, and in lettuce 0.04 (5), 0.05, 0.07 0.11 mg/kg. German GAP for radishes is a "spreading" application at 3 kg ai/ha (field) or 4 kg ai/ha (glass). Similar GAP for soil treatment was reported at comparable application rates for several other crops in a number of countries.
Although no GAP was reported for chlorfenvinphos on lettuce or lamb's lettuce, the trials demonstrated that significant residues may occur in these crops when grown in rotation following soil applications of chlorfenvinphos. Since the trials were reported only in summary form, the Meeting agreed not to estimate a maximum residue level for lamb's lettuce or head lettuce.
Livestock. In a briefly reported trial calves were dipped in a chlorfenvinphos solution at a concentration of 0.037 kg ai/hl. Residues in liver, muscle and kidney were below the LODs of 0.1, 0.05 and 0.05 mg/kg respectively, but residues in the fat were in the range 0.1-0.27 mg/kg. In a trial in which cattle were grazed on treated pasture containing residues of 2.5-17 mg/kg the residues of chlorfenvinphos in the milk were all below 0.01 mg/kg.
The Meeting concluded that there were insufficient data on residues in ruminant feed items to estimate maximum residue levels for the meat, milk or edible offal of ruminants and that the existing CXLs for meat and milk should be withdrawn.
Domestic preparation and processing trials indicated that most of the residue in carrots treated with an EC spray is associated with the crown and the top 1 cm of the root. Removal of the crown alone was reported to lead to the loss of approximately 30% of the residue. Domestic boiling was found to have only a moderate effect on residues, but when carrots were peeled and the top of the roots (crown and next 1 cm) removed only 1-3% of the total residue remained. In a further study residues of 0.07 mg/kg in raw carrots were reduced to 0.02 mg/kg by commercial cooking, which included the addition of brine.
National monitoring data were supplied from Australia, Poland, The Netherlands and the UK.
The Meeting agreed that in view of the lack of studies according to modem standards on metabolism, the stability of residues in stored analytical samples, the mobility of chlorfenvinphos in soil and the residues found in following crops, the estimated maximum residue levels could not be recommended as MRLs. For any further future consideration of MRLs, submission of data on such studies would be needed.
