4.13 Malathion (049)

RESIDUE AND ANALYTICAL ASPECTS

Malathion was evaluated in the periodic review programme by the JMPR in 1999 and re-evaluated in 2004. At its 37^th Session, the CCPR decided to advance the MRLs for apple, citrus and grapes for adoption at step 5. The CCPR also decided to return all other MRLs associated with animal feeds, including cotton seed, maize and wheat, to Step 6 pending review by JMPR of animal feeding studies. These studies were listed as desirable in the 1999 JMPR report, but no data was submitted to the Meeting. In the 2004 JMPR, residues from trials conducted on alfalfa according to GAP confirmed the previous recommendations for this crop.

At this Meeting, animal dietary burden was calculated for cattle and poultry based on the recommendations on animal feed made by the previous Meetings. In addition, animal metabolism studies submitted to the 1999 JMPR were evaluated in light of the calculated dietary burden. No additional GAP information was provided to this Meeting.

Estimated maximum dietary burden of farm animals

DM= dry matter; dw= dry weight; hr= highest residue for animal feed; m= median residues for animal feed; p=processing commodity, *information from the trials or from the FAO Manual

Metabolism studies in animals

Two metabolism studies were evaluated by the 1999 JMPR. In one study conducted with goats dosed at 115 ppm diet for 5 days, malathion was found to be used as a carbon source, with the radioactivity being incorporated in fatty acids, glycerol, tricarboxylic cycle acid intermediates and protein. No malathion or any products arising from primary metabolism of malathion were observed at levels above 0.05 mg/kg in any sample analysed.

In one study conducted in hens, dosed at 25 ppm diet for 4 days, malathion was also found to be used as a carbon source. No malathion or any products of immediate metabolism were observed at levels exceeding 0.02 mg/kg in any of the samples, except the white from one egg on day 1, where significant activity as malathion carboxylic acid was detected.

Residues in animal products

The FAO Manual (2002) states that feeding studies in animals are required where significant residues (> 0.1 mg/kg) occur in crops or commodities fed to animals and metabolism studies indicate that significant residues (> 0.01 mg/kg) may occur in edible tissues. Residues in commodities fed to animals estimated by the JMPR are significant and the calculated dietary burden for ruminants (460 ppm) is much higher than the dose used in the metabolism study in goats. The Meeting concluded that the metabolism study could not be used to estimate the level of malathion residues in commodities from ruminant animals, and confirms that feeding studies with malathion on ruminant animals are desirable.

The Meeting noticed that the highest contribution to the dietary burden of malathion came from crops grown specifically for feed. Residues of malathion in other feed and food commodities, including cereal grains and citrus dried fruit, are low (< 1 mg/kg) and are not expected to make any significant contribution to the animal dietary burden. Although currently there is no recommendation for apple pomace, the recommended HR for apple is 0.28 mg/kg, and the Meeting agreed that the expected residues in apple pomace should also not contribute significantly to the animal dietary burden.

The metabolism study conducted in hens at approximately 10 times the calculated dietary burden indicates that no residues of malathion are expected to be found in tissues and eggs. The Meeting concluded that a feeding study in hens is not necessary. However, no recommendations could be made in poultry commodities as no analytical method in animal products was submitted to this or previous Meetings.

4.14 Methiocarb (132)

RESIDUE AND ANALYTICAL ASPECTS

Methiocarb, an insecticide, acaricide, molluscicide and bird repellent, was first reviewed by the Meeting in 1981. Since then, it was evaluated a number of times both for toxicology and residues.

It was reviewed under the Periodic Review Programme in 1998 for toxicology and in 1999 for residues. The 1998 JMPR allocated a new ADI of 0-0.02 mg/kg body weight and ARfD of 0.02 mg/kg body weight. The 1999 JMPR concluded that the residue should be defined both for enforcement of MRLs and for the estimation of dietary intake as "the sum of methiocarb, methiocarb sulfoxide and methiocarb sulfone, expressed as methiocarb".

The 1999 JMPR estimated provisional maximum residue levels and STMRs for strawberry, leek, cabbages, cauliflower, cucumber, melons, pepper, tomato, pea, maize and hazelnuts. However, due to the lack of appropriate storage stability studies it decided to withdrew the existing Codex MRLs for the above-mentioned commodities (except strawberry) and other commodities for which no data had been submitted to the Meeting.

Methiocarb was identified by the 36^th Session of the CCPR in 2004 for evaluation by the 2005 JMPR. The current Meeting received data to support MRLs for artichoke, barley, Brussels sprout, cabbages, cauliflower, cucumber, grapes, hazelnut, leek, lettuce, maize, melons, onion, pea, pepper, potato, sugar beet, sunflower, tomato and wheat. The data of some crops had been submitted to the 1999 JMPR which reviewed them and made provisional recommendations based on them. The Meeting, however, agreed that these data should be reviewed along with new data in view of new GAP information and new JMPR policies established for evaluation since 1999.

Methods of analysis

The Meeting received information on a new HPLC method which was developed after the last evaluation and used in supervised trials conducted in recent years. Information on the validation of previously reviewed method, Bayer method number 00014, for the determination of methiocarb, methiocarb sulfoxide and methiocarb sulfone in grape and melon pulp and peel was also provided.

The new method determines methiocarb, methiocarb sulfoxide and methiocarb sulfone in plant materials separately using HPLC-MS/MS. The analytical procedure includes extraction with either a mixture of acetonitrile/water (samples with low lipid content) or acetonitrile saturated with n-hexane followed by partition with n-hexane (samples with high lipid content), clean-up on a non-polar column, analysis by a reverse phase HPLC with an acidic acetonitrile/water eluent on a silica based C₁₈ column and detection by tandem mass spectrometry with electrospray ionization. In the case of starch-containing sample materials, a cysteine solution was added for stabilization. The product ions of 169, 122 and 185 amu were used for quantification of methiocarb, methiocarb sulfone and methiocarb sulfoxide respectively. The limit of quantitation (LOQ) was 0.01 mg/kg for each of the three compounds in matrices in supervised trials except in the analysis of barley straw and wheat straw for which the LOQ was 0.05 mg/kg. Mean recoveries of these compounds from matrices in supervised trials with fortification at LOQ and 10 × LOQ were in the range of 72 to 104% for these compounds with relative standard deviations below 17%.

The above method is generally more sensitive than other methods but as HPLC-MS/MS is not considered common equipment in the world, this HPLC-MS/MS method could not be recommended for enforcement purposes at the international level.

Bayer method number 00014 with the modification M001 (reported in the 1999 JMPR Evaluation; HPLC method with post-column derivatization) was successfully validated for grape with the LOQ at 0.02 mg/kg for each of the three compounds and mean recoveries of these compounds at the fortification levels of 0.02, 0.10 and 1.0 m/kg ranged between 79-107%. This method was also successfully validated for melon pulp and melon peel with the LOQ at 0.02 mg/kg for each of the three compounds and mean recoveries of these compounds at the fortification levels of 0.02, 0.10 and 1.0 mg/kg ranged between 81 and 126%.

Stability of pesticide residues in stored analytical samples

A 2-year deep-freezer storage stability study was conducted with methiocarb, methiocarb sulfone and methiocarb sulfoxide in matrices of plant origin. Shredded samples of grape (bunch), field peas, potato and rapeseed were fortified with methiocarb, methiocarb sulfone and methiocarb sulfoxide at 0.20 mg/kg. The samples were stored at -18°C or below for up to 733-734 days. Methiocarb, methiocarb sulfone and methiocarb sulfoxide were analysed by the HPLC-MS/MS method mentioned above. During the storage period, the sum of methiocarb, methiocarb sulfone and methiocarb sulfoxide did not decrease significantly except in the case of rapeseed, where a 25% decrease was observed, which was still within the acceptable range. In the case of potato, some conversion from the parent compound to sulfoxide was shown.

The Meeting concluded that these results indicate that the data from supervised trials were acceptable for estimating maximum residue levels, STMRs and HRs as samples had been stored no longer than 2 years.

No information was available on the storage stability of these compounds in matrices of animal origin.

Results of supervised trials on crops

The Meeting received supervised trials involving methiocarb on artichoke, barley, Brussels sprout, cabbage, cauliflower, cucumber, grape, hazelnut, leek, lettuce, maize, melon, onion, pea, pepper, potato, sugar beet, sunflower, tomato and wheat.

A number of the residue trials were carried out using a 50 wettable powder (WP) or a 500 soluble concentrate (SC) formulation. These formulations are considered to be interchangeable with regard to the residue behaviour of the methiocarb active ingredient. The Meeting concluded that the data generated with either of the two formulations could be used to support the other.

For spreader applications, ready-to-use (RTU) bait formulations (containing 2, 3 or 4 percent methiocarb) were used in the residue trials. The bait formulations are designated as either RB or GR. Both names refer to the same formulation and the designation RB is used in this review.

Residues were determined as methiocarb sulfone and calculated and expressed as methiocarb (a GLC method using oxidation by permanganate), or determined separately and the sum of the three components was expressed as methiocarb (HPLC methods). For the calculation of total residues, the Meeting took a similar approach as the 1999 JMPR as indicated in the following table.

The 1999 Meeting considered that a practical LOQ for enforcement purposes was 0.05 mg/kg for commodities of plant and animal origin except for milk for which the practical LOQ was 0.005 mg/kg. The current Meeting concluded that where total residues arising from supervised trials for a crop were all below LOQ which is smaller than 0.05 mg/kg, a maximum residue level should be recommended at 0.05 * mg/kg.

For commodities where the supporting trials used in the estimation of maximum residue levels all reported residues below the limit of quantification, even at exaggerated rates, the Meeting, taking into account the results of the plant metabolism studies, agreed to estimate STMRs, median residue levels, HRs and highest residue levels of 0 mg/kg, indicating that residues are not expected.

Grapes

A total of eight trials were conducted in France (1), Greece (4), Italy (1), Portugal (1) and Spain (1). These trials were carried out with 2 or 3 spray applications at 1 kg ai/ha.

Registered use patterns for grapes related to the supervised trials are as follows:

# Last application before flowering

In a total of five trials, one each in France, Greece, Italy, Portugal and Spain, methiocarb was applied three times instead of twice as specified by GAP in Greece, Italy or Spain. The analysis of grapes taken immediately before the last application and 21 days after the last application indicates that one extra application did not have a significant effect on residue concentrations taken at the PHI. The Meeting agreed to use the results of trials with three applications for estimating a maximum residue level, STMR and HR.

All eight trials were evaluated against GAP in Italy. Among all eight trials, five trials (one each in France, Greece, Italy, Portugal and Spain) were in accordance with Italian GAP. Total residues in ranked order, were: 0.13, 0.16, 0.24, 0.27 and 0.34 mg/kg. The Meeting considered it inadequate to estimate a maximum residue level for grapes on a basis of five valid trials.

The Meeting also evaluated these eight trials against the Greek GAP, with a PHI of 42 days. Seven trials were in accordance with Greek GAP and total residues in ranked order, were: 0.04(2), 0.07, 0.10, 0.12, 0.16 and 0.20 mg/kg. The Meeting concluded that seven valid trials were not sufficient to estimate a maximum residue level for grapes.

Leek

Eight supervised residue trials were conducted on leek in France using the 50WP formulation and four trials in the Netherlands using the 500 SC formulation. In each trial, 3 spray treatments at approximately 0.75 kg ai/ha were carried out.

Registered use patterns for leek related to the supervised trials are as follows:

No GAP information was available from the Netherlands but the results of trials conducted in the Netherlands were reviewed against the GAP of Belgium.

Eight trials conducted in France were in accordance with GAP in France. Residues in leek in these trials were in rank order: 0.07, 0.09, 0.10, 0.13, 0.17, 0.17, 0.21 and 0.33 mg/kg.

Four residue trials conducted in the Netherlands were in accordance with Belgian GAP. Residues in leek in these trials were: < 0.02 (3) and 0.03 mg/kg.

As residues arising from French trials and those from Dutch trials did not appear to belong to the same population, the results from French trials were used to estimate a maximum residue level, STMR and HR. The Meeting estimated a maximum residue level, STMR and HR for leek at 0.5, 0.15 and 0.33 mg/kg respectively.

Onion, bulb

Eight supervised trials were conducted using the 50 WP formulation in France, Greece, Portugal and Spain. In each trial 2 kg ai/ha was applied twice.

Registered use pattern for onion related to the supervised trials is as follows:

In all of eight trials, methiocarb was applied only twice instead of three times as specified in the Belgian GAP and the application rate was 1.0 kg ai/ha instead of the 0.75 kg ai/ha GAP rate. As the analysis of samples taken immediately before the last application indicated that no carry-over of residues was expected, the Meeting decided to use these trial data for estimating a maximum residue level. All eight trials reviewed were regarded as in accordance with Belgian GAP and total residues were in ranked order: < 0.01 (4), 0.04, 0.05, 0.06 and 0.35 mg/kg.

The Meeting estimated a maximum residue level, STMR and HR for onion, bulb at 0.5, 0.025 and 0.35 mg/kg respectively.

Brussels sprouts

A total of eight supervised trials were conducted in Belgium (1), France (2), Germany (2), the Netherlands (1) and the UK (2) using 4RB formulation (ready to use bait).

Registered use patterns for Brussels sprouts related to the supervised trials are as follows:

As no GAP information was provided for Belgium, France, Germany and the Netherlands, the results of trials conducted in these countries were reviewed against the Irish GAP for the 4RB formulation. From the six trials conducted in accordance with Irish GAP no quantifiable residues of methiocarb, methiocarb sulfone and methiocarb sulfoxide were found: < 0.01 mg/kg (6).

The two UK trials were also in accordance with the Irish GAP for the 4RB and total residues found were: < 0.01 mg/kg (2).

The Meeting estimated a maximum residue level, STMR and HR for Brussels sprouts at 0.05*, 0.01 and 0.01 mg/kg respectively.

Cabbages, Head

Eight supervised trials were conducted on cabbage with methiocarb 500 SC or 50 WP applied as a spray in Belgium, Germany and the Netherlands. An additional 14 trials were conducted in Belgium, France, Germany, the Netherlands and the UK where the RTU bait formulation of methiocarb was applied.

Registered use patterns for cabbages related to the supervised trials are as follows:

In two trials conducted in Belgium, two in Germany and four in the Netherlands, methiocarb was sprayed three times at rates ranging from 0.70 to 0.75 kg ai/ha. These trials were regarded as matching the maximum GAP in Belgium by the 1999 JMPR when the GAP at the time permitted a maximum of three applications at a rate of 0.75 kg ai/ha. Due to a change in GAP, which permits a maximum of four applications at a rate of 0.50 kg ai/ha, the trials were no longer in accordance with the maximum GAP of Belgian. In these trials, total residues at a PHI of 14 days ranged from < 0.02 to 0.05 mg/kg. The application rates of these trials were comparable to the Italian GAP (a maximum of 2 applications) but some trials indicate potential carry-over of residues from earlier application and therefore these trials were not used for estimating a maximum residue level.

All six trials conducted in Germany with the application rate of 0.12 kg ai/ha using 4 RB formulation were regarded as in accordance with the maximum GAP of Germany and residues found were: < 0.05 mg/kg (6).

Of eight trials, one conducted with two applications at the rate of 0.20 kg ai/ha in Belgium, one in France, four in Germany, one in the Netherlands and one in the United Kingdom, four trials were in accordance with Irish GAP (application number not specified; 0.22 kg ai/ha, PHI 7 days) the residues found were: < 0.01 (3) and 0.08 mg/kg. In the other four trials, no samples were taken at the PHI of 7 days but all three components were below or at the LOQ of 0.01 mg/kg even on day 0.

Combined residue results in ranked order were: < 0.01 (3), < 0.05 (6) and 0.08 mg/kg. The Meeting estimated a maximum residue level, STMR and HR for cabbages, head at 0.1, 0.05 and 0.08 mg/kg respectively.

Cauliflower

Four supervised trials were conducted on cauliflowers in Germany using a RTU bait formulation. Residues were determined as methiocarb sulfone and calculated as methiocarb.

Registered use patterns for cauliflower related to the supervised trials are as follows:

The four trials were conducted in accordance with the maximum GAP of Germany. However, in one trial the cauliflower florets were not analysed. Residues from the three valid trials were all < 0.05 mg/kg.

The Meeting agreed that three trials were insufficient for estimating a maximum residue level and STMR for cauliflower. The 1999 JMPR concluded that the data on cabbages could be extrapolated to cauliflowers as the GAP is identical and the treatments are applied to the ground, not foliar where differences in plant structure might lead to different residue concentrations. The Meeting estimated a maximum residue level, STMR and HR for cauliflower at 0.1, 0.05 and 0.08 mg/kg respectively.

Cucumber

A total of nine supervised trials were carried out in France (5 in greenhouse), the Netherlands (1 in greenhouse), Portugal (1 in greenhouse) and Spain (2 in field). In the field trials 2 spray applications at 1.0 kg ai/ha were carried out, while in the greenhouse trials 1-3 spray applications at rates between 0.8 and 1.1 kg ai/ha were made.

Registered use patterns for cucumbers related to the supervised trials are as follows:

* Last application before flowering

Two field trials conducted in Spain were in accordance with Spanish GAP. Residues found were < 0.04 mg/kg (2).

Greenhouse trials conducted in France (1), the Netherlands (1) and in Portugal (1) used application rates of 1.0 and 1.1 kg ai/ha. These were regarded to be in accordance with Spanish GAP as the rates were within ±30% of the maximum rate specified in the Spanish GAP. Residues found were: 0.04, 0.10 and 0.21 mg/kg.

Other trials conducted in greenhouses in France were not in accordance with any reported GAP.

Residues in samples from the greenhouse trials were found to be significantly higher than those from field trials and therefore these results could not be combined. The Meeting concluded that there was insufficient data to estimate a maximum residue level in cucumber.

Melons

A total of eleven supervised trials were conducted on melons in France (4), Italy (1), Portugal (2 in greenhouses) and Spain (4). In these trials methiocarb was sprayed 1 to 3 times at application rates ranging from 0.75 to 1.1 kg ai/ha.

Registered use patterns for melons related to the supervised trials are as follows:

Two greenhouse trials conducted in Portugal were in accordance with Portuguese GAP and residues found in whole fruits were 0.25 and 0.48 mg/kg respectively.

Two field trials conducted in Spain in 1993 and two trials in France in 1996 were also in accordance with Portuguese GAP, with residues found in ranked order of: 0.07, 0.10, 0.12 and 0.16 mg/kg.

In one trial in Italy, two other trials in Spain and one other trial in France conducted in the field, samples (whole fruit) were taken at a PHI of 21 days (GAP in Italy) and did not contain any of the three components above the LOQ of 0.02 mg/kg.

Since the residues in whole fruits taken 7 and 21 days after treatment were significantly different, the Meeting decided that these values could not be combined. Residues in samples taken 7 days after treatment in greenhouses and those from field trials were also significantly different and therefore could not be combined. The Meeting estimated a maximum residue level for melons, except watermelon, at 0.2 mg/kg on the basis of four field trials conducted in Spain (2) and France (2).

In these trials residues in pulp were: < 0.02 mg/kg (4). The Meeting estimated an STMR and HR at 0.02 and 0.02 mg/kg.

Peppers

A total of nine supervised trials were conducted on sweet peppers: two in Portugal in greenhouses and seven in Spain in greenhouses (5) and field (2). The number of spray applications was either 2 or 3 with application rates ranging from 1.16 to 1.5 kg ai/ha.

Registered use patterns for peppers related to the supervised trials are as follows:

All seven greenhouse trials were in accordance with Spanish GAP. In two trials only the sum of the three components was reported with no information on the levels of individual components provided. Residues found in ranked order were: 0.22, 0.67, 0.84, 0.92, 1.2, 1.3 and 1.3 mg/kg.

One field trial conducted in Spain with the variety Lamuyo was in accordance with Spanish GAP. The residues found were 1.5 mg/kg.

Residues from valid trials in ranked order were: 0.22, 0.67, 0.84, 0.92, 1.2, 1.3, 1.3 and 1.5 mg/kg. The Meeting estimated a maximum residue level, STMR and HR for sweet peppers at 2, 1.06 and 1.5 mg/kg respectively.

Tomato

The Meeting received information on supervised residue trials on tomatoes in Germany (2 in greenhouses) France, Greece (1 in greenhouses), Portugal (1 in greenhouses) and Spain (7 in greenhouses and field). The spray application rate ranged from 1.0 to 1.5 kg ai/ha with either 2 or 3 applications made.

Registered use patterns for tomato related to the supervised trials are as follows:

Two trials conducted in Germany and one in Greece in greenhouses were evaluated against Spanish GAP but samples were taken only up to 3 days post treatment and therefore could not be used for estimating a maximum residue level.

One greenhouse trial conducted in Portugal was in accordance with Spanish GAP with a residue concentration found of 0.80 mg/kg.

Two greenhouse trials conducted in Spain in 1993 used rates more than 30% above the maximum GAP rate. Residues found were 0.22 and 0.58 mg/kg.

Three field trials conducted in Spain in 1990 were in accordance with Spanish GAP with residues levels found of < 0.04 (2) and 0.11 mg/kg.

Two field trials conducted in Spain in 1988 were in accordance with Spanish GAP. However, only the sum of the three components was reported with no information on the levels of individual components provided. The residues found in these were 0.17 mg/kg (2).

The greenhouse trials conducted seemed to result in higher residues than the trials conducted in the field and the Meeting therefore decided these results could not be combined. Residues from field trials matching Spanish GAP in ranked order were: < 0.04 (2), 0.11, 0.17 and 0.17 mg/kg.

The Meeting concluded that five valid trials were insufficient to estimate a maximum residue level for tomato.

Lettuce

A total of eight supervised trials were conducted on lettuce in Germany (7) and the United Kingdom (1) with an application rate of 0.12 or 0.45 mg ai/ha using the RTU bait formulation. Residues were determined as methiocarb sulfone and calculated as methiocarb.

Registered use patterns for lettuce related to the supervised trials are as follows:

Seven trials conducted in Germany were in accordance with the maximum GAP in Germany. Residues levels found were: < 0.05 mg/kg (7).

One trial from the United Kingdom used approximately four times (4x) the GAP rate resulting in residues below the LOQ on day 15 after treatment.

The number of valid trials was seven, and together with the supporting information above, the Meeting estimated a maximum residue level, STMR and HR at 0.05*, 0.05 and 0.05 mg/kg respectively.

Peas

Eight supervised residue trials were performed in Germany on peas using the 500 FS seed treatment formulation according to German GAP. Residues were determined as methiocarb sulfone and calculated as methiocarb.

Registered use pattern for field peas related to the supervised trials is as follows:

Residues in peas with pod were: < 0.05 (6) and 0.07 mg/kg. Residues in dry peas were: < 0.05 (4) and 0.06 mg/kg.

The Meeting estimated a maximum residue level and STMR for both peas (pods and succulent=immature seeds) and pea (dry) at 0.1and 0.05 mg/kg respectively. An HR of 0.05 mg/kg was estimated for peas (pods and succulent=immature seeds).

Potato

Two supervised trials were performed in the United Kingdom with 3 applications of the ready-to-use bait formulation at 0.22 kg ai/ha. Potatoes were harvested after a PHI of 18-20 days. Eight other trials were performed in Germany, the Netherlands and the United Kingdom with a lower annual rate and frequency of treatment, i.e., 2 × 0.15 kg ai/ha with a shorter PHI of 7 days.

Registered use patterns for potatoes related to the supervised trials are as follows:

* Last application prior to desiccation of leaves

Two UK trials were in accordance with Irish GAP and no quantifiable residues were found in tubers harvested 18 or 20 days after treatment. Residues were: < 0.02 mg/kg (2).

Concerning the other eight trials, and taking into consideration the shorter PHI of 7 days and that the method of application was spreading, these trials could be regarded as appropriate for estimating a maximum residue level. There were no quantifiable residues found in samples taken: < 0.01 mg/kg (8).

The Meeting estimated a maximum residue level, STMR and HR for potato at 0.05*, 0.01 and 0.02 mg/kg respectively.

Sugar beet

Four supervised trials on sugar beet were conducted with 2 applications at 0.15 kg ai/ha of the ready-to-use formulation (2RB) (France, Germany and the United Kingdom) and 10 trials with 2 applications of 0.12 g ai/ha of the ready-to-use bait formulation (4RB) (France, Germany, Italy, Spain and the United Kingdom). The last treatment of soil was conducted at growth stages 9-14 (BBCH - scale).

Registered use patterns for sugar beet related to the supervised trials are as follows:

* Last application should be made before the specified BBCH growth stage.

All of the 14 trials were in accordance with the maximum GAP in France or Germany or within 30% of the maximum GAP in France. There were no quantifiable residues found in sugar beet roots (LOQ 0.01 mg/kg).

The Meeting estimated a maximum residue level, STMR and HR for sugar beet at 0.05*, 0.01 and 0.01 mg/kg respectively.

Artichoke, Globe

A total of four supervised trials were conducted on artichoke in France (1) and Italy (3). Methiocarb was applied as a ready-to-use bait twice at a rate of 0.1 or 0.12 kg ai/ha.

Registered use patterns for artichokes related to the supervised trials are as follows:

One trial in France and one trial in Italy in 2001 were in accordance with maximum GAP rate in France but no samples were analysed 15 days after application. Together with the two other trials from Italy, they were reviewed against Italian GAP although the formulations were not identical.

In all trials no quantifiable residues were found in samples taken either on day 14 (if available) or day 21 (LOQ 0.01 (2) or 0.005 (2) mg/kg).

The Meeting estimated a maximum residue level, STMR and HR for artichoke, globe at 0.05*, 0.005 and 0.01 mg/kg respectively.

Barley

A total of 12 residue trials were performed on barley in France, Germany, Greece and Italy using the RTU bait formulation. The trials were conducted with 2 applications at 0.12 kg ai/ha. In all trials the last application was conducted at growth stage 12. PHIs for ripe grains and straw ranged between 76 and 141 days.

Registered use patterns for barley related to the supervised trials are as follows:

* Last application should be made before the specified BBCH growth stage.

All twelve trials were in accordance with German GAP. No quantifiable residues were found in the harvested grain (LOQ 0.01 (9) or 0.05 (3) mg/kg).

The Meeting estimated a maximum residue level, STMR and highest residue for barley at 0.05*, 0 and 0 mg/kg respectively.

Wheat

A total of nine residue trials were conducted on wheat in France, Germany, Portugal and the United Kingdom in 1991, 2000 and 2001 using the ready-to-use bait formulation at a rate of 0.12 or 0.22 kg ai/ha applied twice. In these trials, the growth stage at last application ranged between 11 and 33.

Registered use patterns for wheat related to the supervised trials are as follows:

* Last application should be made before the specified BBCH growth stage.

Seven trials conducted in France and Germany were in accordance with German GAP. No quantifiable residues were found in the harvested grains (LOQ 0.01 mg/kg).

In two UK trials, a 2 × rate was used with the last application at growth stage 30 or 33. No quantifiable residues were found in harvested grains (LOQ 0.04 mg/kg).

The Meeting estimated a maximum residue level, STMR and highest residue for wheat at 0.05*, 0 and 0 mg/kg respectively.

Maize

A total of 23 supervised trials were conducted on maize using the 500 FS seed treatment formulation. The trials were carried out in Belgium, France, Germany, Greece, Italy and Spain. The application rate was 0.5 kg ai/100 kg seed.

An additional four trials were conducted with methiocarb granules applied twice at a rate of 0.12 kg ai/ha in Germany, Italy and Spain. The last application was conducted at growth stages 11-13.

Registered use patterns for maize related to the supervised trials are as follows:

^# Last application should be made before the specified BBCH growth stage.

Fifteen trials conducted in Belgium, France, Greece, Italy and Spain, using the 500 FS seed treatment formulation, were all done in accordance with the GAP of Belgium, France and Germany (identical GAP). At the time of harvest no quantifiable residues were found in the grain: < 0.01 mg/kg (15).

In the four trials conducted with the granular treatment, a bait formulation was applied to the ground and not incorporated into the soil and therefore was unlikely to lead to residues in the harvested maize grain: < 0.01 mg/kg (4).

Based on 15 trials using the FS seed treatment formulation, the Meeting estimated a maximum residue level, STMR and highest residue at 0.05*, 0 and 0 mg/kg for maize.

Hazelnut

Five trials were conducted in Turkey on hazelnuts in 1 year. Methiocarb was applied by dusting or spraying.

The registered use pattern for hazelnut available to the Meeting is as follows:

All five Turkish trials were according to Turkish GAP with no quantifiable residues found in hazelnut kernels (LOQ 0.04 mg/kg).

The Meeting estimated a maximum residue level, STMR and HR for hazelnut at 0.05*, 0.04 and 0.04 mg/kg respectively.

Rape-seed

A total of 10 supervised trials were conducted on rape with methiocarb 500 FS used for seed dressing at a seed rate of 2.5 kg ai/100 kg of seed. Trials were carried out in France (5), Germany (4) and in the UK (1). Thirteen other trials were conducted with a RTU bait formulation applied twice at a rate of 0.12 kg ai/ha in Belgium (2), France (3), Germany (5), Sweden (1) and the UK (2).

Registered use patterns for rape-seed related to the supervised trials are as follows:

* Last application should be made before the specified growth stage.

Ten supervised trials conducted using the 500FS seed treatment formulation were in accordance with French GAP. No quantifiable residues were found in the harvested seeds (LOQ 0.01 mg/kg (10)).

The thirteen granular treatment trials were conducted in accordance with Irish GAP. No quantifiable residues were found in the harvested seeds (LOQ 0.01 (10) or 0.05 (3) mg/kg).

The Meeting estimated a maximum residue level and STMR at 0.05* and 0 mg/kg respectively.

Sunflower seed

Four supervised trials were conducted in France (3) and Italy (1) using the ready-to-use bait formulations. The last application was performed at growth stage 31-51, which corresponded to a PHI of 80-86 days.

Registered use patterns for sunflower related to the supervised trials are as follows:

* Last application should be made before the specified BBCH growth stage.

Three of four trials were in accordance with the GAP in Ireland or the UK. In another trial the last application was carried out at growth stage 53.

There were no quantifiable residues in harvested seeds even with the last application at growth stage 53 (LOQ 0.01 mg/kg).

The Meeting estimated a maximum residue level and STMR for sunflower seed at 0.05* and 0 mg/kg respectively.

Animal feeds

Pea vines/hay

Residues in whole plant other than pods from trials matching GAP (see the section on peas) in rank order were: 0.04, < 0.05 (7) mg/kg.

No information was available for moisture content in pea vines. The Meeting estimated an STMR and highest residue for pea vines on a fresh weight basis at 0.05 and 0.05 mg/kg respectively for the purpose of calculating the animal dietary burden.

Residues in pea straw at the time of harvest were: < 0.05 (2), 0.08 and 0.38 mg/kg.

No information was available for moisture content in pea hay. The Meeting estimated an STMR and highest residue for pea hay on a fresh weight basis at 0.065 and 0.38 mg/kg respectively for the purpose of calculating the animal dietary burden. The Meeting also estimated a maximum residue level of 0.5 mg/kg (dry weight basis) for pea hay or pea fodder (dry) using the percentage of dry matter of 88% as listed in Appendix IX of the FAO Manual (FAO, 2002).

Sugar beet, Leaves or Tops

Residues in sugar beet leaves from trials matching GAP (see the section on sugar beet) were below the LOQ of 0.01 mg/kg (14). No information was available for moisture content in sugar beet leaves. The Meeting estimated an STMR and highest residue for sugar beet leaves on a fresh weight basis at 0.01 and 0.01 mg/kg respectively these values were used to calculate the animal dietary burden.

Barley forage/fodder

Residues in green material from all twelve trials which matched the German GAP (see the section on barley) were: < 0.01 (9) and < 0.05 (3) mg/kg. No information was available for moisture content in the barley forage. The Meeting estimated an STMR and highest residue for barley forage on a fresh weight basis at 0.01 and 0.05 mg/kg respectively for the purpose of calculating the animal dietary burden.

Residues in straw taken at the time of normal grain harvest from all twelve trials, which matched the German GAP were: < 0.05 (12) mg/kg. No information was available for moisture content in the barley fodder. The Meeting estimated an STMR and highest residue for barley fodder on a fresh weight basis at 0.05 and 0.05 mg/kg respectively for the purpose of calculating the animal dietary burden. The Meeting also estimated a maximum residue level of 0.05 mg/kg (dry weight basis) for barley straw and fodder, using the dry matter percentage of 89% as listed in Appendix IX of the FAO Manual (FAO, 2002).

Wheat forage/fodder

Residues in green plant material from seven trials matching German GAP (see the section on wheat) were: < 0.01 (7) mg/kg. In two UK trials, a 2x rate was used with the last application at growth stage 30 or 33. Residues in green plant material were below the LOQ of 0.1 mg/kg. No information was available for moisture content in wheat forage. The Meeting estimated an STMR and highest residue for wheat forage on a fresh weight basis at 0.01 and 0.01 mg/kg respectively for the purpose of calculating the animal dietary burden.

Residues in straw taken at the time of grain harvest from all seven trials, which matched German GAP were: < 0.05 (7) mg/kg. In two UK trials, a 2 × rate was used with the last application at growth stage 30 or 33. Residues in straw were below the LOQ of 0.1 mg/kg. No information was available for moisture content in the wheat straw. The Meeting estimated an STMR and highest residue for wheat fodder on a fresh weight basis at 0.05 and 0.05 mg/kg respectively for the purpose of calculating the animal dietary burden. The Meeting also estimated a maximum residue level of 0.05 mg/kg (dry weight basis) for wheat straw and fodder, dry, using the dry matter percentage of 89% as listed in Appendix IX of the FAO Manual (FAO, 2002).

Maize forage

In supervised trials, residues were also determined on a whole plant basis, without roots. Whole plant residues, without roots, found from samples taken on the day of the last harvest of corn-on-the-cob, from trials matching GAP (see the section on maize), were: < 0.01 mg/kg (16).

No information was available for moisture content in maize forage. The Meeting estimated an STMR and highest residue for maize forage on a fresh weight basis at 0.01 and 0.01 mg/kg respectively for the purpose of calculating the animal dietary burden.

Rape forage

Residues in green plant materials of rape, taken close to normal harvest, from trials matching GAP (see the Section on rape-seed) in ranked order were: < 0.01 (19), < 0.05 (3) and 0.05 mg/kg.

No information was available for moisture content in rape forage. The Meeting estimated an STMR and highest residue for rape forage on a fresh weight basis at 0.01 and 0.05 mg/kg respectively for the purpose of calculating the animal dietary burden.

Fate of residues during processing

Grapes

A wine processing study was conducted with table grapes to which methiocarb 50WP was sprayed twice at an application rate of 1.0 kg ai/ha with the last application occurring 42 days prior to harvest.

Residues of methiocarb, methiocarb sulfone, methiocarb sulfoxide and the total residues were determined in grape bunches, berries and in wine. The calculated total residues were 0.07 mg/kg for grape bunches, 0.06 mg/kg for berries and 0.03 mg/kg for wine. Processing factors are shown below.

Farm animal dietary burden

The Meeting estimated the farm animal dietary burden of methiocarb residues, using the diets listed in Appendix IX of the FAO Manual (FAO, 2002).

In the tables below, farm animal dietary burden was calculated by summing the residue contribution of each feed (mg/kg).

Estimated maximum dietary burden of farm animals

Estimated STMR value for dietary burden of farm animals.

The dietary burden of methiocarb, for estimates of animal commodity MRLs and STMRs are respectively: beef cattle, 0.21 and 0.04 ppm; dairy cattle, 0.32 and 0.06 ppm; and poultry, 0 and 0 ppm.

Farm animal feeding studies

The 1999 JMPR received and reviewed farm animal feeding studies.

In one feeding study, dairy cows were given feed containing methiocarb at the equivalent of 0, 10, 30 and 100 ppm methiocarb for 29 days. Maximum methiocarb residue in milk on day 29 was 0.007, 0.020 and 0.033 mg/kg at the 10, 30 and 100 ppm feeding levels, respectively. No residues (< 0.05 mg/kg total methiocarb) were found in any tissue at any feeding level, except 0.08-0.1 mg/kg methiocarb in liver at 30 and in kidney at 100 ppm.

At the estimated maximum animal dietary burden of 0.32 mg/kg, maximum residue levels were calculated to be far below the LOQ for enforcement at 0.005 mg/kg in milk and 0.05 mg in meat and edible offal of mammals. The Meeting estimated maximum residue levels in meat and edible offal of mammals at the practical LOQ at 0.05 * mg/kg and STMR at 0 mg/kg and in milk at 0.005 mg/kg and 0 mg/kg respectively. An HR of 0 mg/kg was estimated for meat and edible offal of mammals.

In one poultry feeding study, hens were fed a diet containing methiocarb and methiocarb sulfoxide (9:1) for 28 days, at rates ranging from 0 to 360 ppm in the feed. The sum of methiocarb and methiocarb sulfoxide was below the LOQ of 0.02 mg/kg in muscle, skin and fat at all dose levels except 0.02 mg/kg in skin at the 360 ppm feeding level. In eggs (28 days) residues were 0.03 and 0.06 mg/kg at 120 and 360 ppm level respectively and in giblets (heart, gizzard and liver), 0.06, 0.13 and 0.13 mg/kg at 60, 120 and 360 ppm level respectively.

No residues were expected to occur in feed items for poultry, such as barley, maize and wheat grains. The Meeting therefore concluded that maximum residue levels for poultry tissues and eggs could be estimated at the practical LOQ of 0.05 * mg/kg, STMR at 0 mg/kg and HR at 0 mg/kg for poultry meat, edible offal and eggs.

The above maximum residue levels for animal commodities were, however, not recommended for use as maximum residue limits by Codex as the information on the storage stability in animal tissues had not been submitted.

Plant commodities and animal commodities

Definition of the residue for compliance with MRLs: the sum of methiocarb, methiocarb sulfoxide and methiocarb sulfone, expressed as methiocarb

Definition of the residue for estimation of dietary intake: the sum of methiocarb, methiocarb sulfoxide and methiocarb sulfone, expressed as methiocarb

DIETARY RISK ASSESSMENT

Long-term intake

The International Estimated Dietary Intakes (IEDIs) were calculated for the five GEMS/Food regional diets using STMR for vegetables, cereals, oil seeds and hazelnuts estimated by the current Meeting and the STMR for strawberry estimated by the 1999 JMPR (Annex 3). The maximum ADI is 0.02 mg/kg and the calculated IEDIs were 0-2% of the maximum ADI. The Meeting concluded that the intake of residues of methiocarb resulting from the uses considered by the current JMPR was unlikely to present a public health concern.

Short-term intake

The International Estimated Short-Term Intakes (IESTIs) of methiocarb by the general population and by children were calculated for commodities for which STMRs or STMR-Ps estimated by the current Meeting where information on consumption was available. An HR of 0.83 mg/kg was estimated for strawberry on a basis of data submitted to and reviewed by the 1999 JMPR (Annex 4). The ARfD is 0.02 mg/kg and the calculated IESTIs for children up to 6 years range from 0 to 70% and those for general population from 0 to 50% of the ARfD. The Meeting concluded that the short-term intake of residues of methiocarb from uses considered by the current Meeting was unlikely to present a public health concern.