CARTAP JMPR 1978 Explanation This pesticide was previously evaluated by the 1976 Meeting (FAO/WHO, 1977b), when a temporary ADI was established and some temporary MRLs were recommended and various requirements for additional information were recorded. Some of this information had since become available for evaluation. Attention had also been drawn to the need to re-examine the MRL recommended for dried green tea to take account of higher residues found in tea grown in the shade. Special explanatory note Certain of the temporary MRLs, although listed correctly in the Report of the 1976 Meeting (FAO/WHO 1977a), were incorrectly recorded in the Monograph (FAO/WHO 1977b). The correct figures are listed again at the end of this Monograph. EVALUATION FOR ACCEPTABLE DAILY INTAKE BIOCHEMICAL ASPECTS Absorption, distribution and excretion Groups of rats (5 female, SD-JCL Strain/group) and mice (4 male, ICR/JCL Strain/group) were administered 35S-cartap HCL by gavage at a dose of 20 mg/kg body weight. In studies on the metabolic fate, cartap was previously shown to have been rapidly absorbed and eliminated in urine within 24 hours following a single acute oral dose. In extensions of previous studies rats and mice were shown to excrete cartap rapidly. In urine, 94 and 89% of the administered dose was excreted within 24 hours in rats and mice, respectively. There were no apparent differences noted in the absorption and excretion in the two rodent species with respect to both qualitative and quantitative recovery of urinary metabolites. Cartap was rapidly absorbed, metabolized and excreted in both rats and mice. Several metabolites were identified confirming the principle routes of degradation. There was no storage of cartap or its metabolites in the body as might be expected with this predominantly water-soluble chemical. (Fujita et al., 1971) Biodegradation In preliminary experiments where cartap was administered by intravenous injection it was found to be rapidly metabolized through two principle routes of degradation, hydrolysis and oxidation (Fujita et al., 1971). Further studies on the absorption and metabolism of cartap administered orally to rats has confirmed the presence of metabolites and the principle routes of degradation-hydrolysis of the carbonyl carbon and oxidation of the sulfur atom to the sulfoxide (S O), sulfone (SO2) and ultimately the sulfate (SO3H) (Kamesaki et al., 1976a). These studies in rats confirmed and expanded the original conclusions by elucidating an extensive degradation pattern. Approximately 85% of the administered oral dose to rats was found in urine within 48 hours after treatment. Approximately 75% of the recovered radioactivity was found as nonpolar lipophilic components, 23% were polar components and 1% was found as sulfates. On the following page is a probable pathway for the metabolic fate of cartap which accounts for approximately 70% of the observed products. An additional 10% of the administered oral dose of cartap was characterized as 2-methylsulfinyl-3-methylthioprop-1-ene (7.2%) and 2,3-di(methylsulfinyl) prop-1-ene (2.0%), two liposoluble metabolites representing further degradation of the molecule (The origin of these products is unclear based on the structural configuration of cartap. These structures, although consistent with the IR and NMR spectral evaluation are difficult to imagine as coming from the cartap molecule). Cartap is readily hydrolyzed to nereistoxin, a naturally occurring insecticidal substance isolated from the marine segmented worms, Lumbrineris heteropoda. Extensive information is available on the chemistry and synthesis of nereistoxin and its derivatives, of which cartap hydrochloride is the most potent. Nereistoxin is in an apparent equilibrium with its dihydronereistoxin derivative. In mammals, nereistoxin is methylated and oxidized at the sulfur atom as well as undergoing a series of oxidative demethylation reactions at the dimethylaminomoiety. A small (> 1%) quantity of products was observed to correspond to sulfates. In rice plants grown in hydroponic solutions or under similated field conditions containing 35S cartap, absorption and distribution was rapid with cartap accumulating in all parts of the plant. Extensive degradation of cartap was found to occur rapidly with incorporation of 35S into natural components (sulfur-containing amino acids). Prior to complete degradation, cartap was observed to be degraded through a series of similar oxidative pathways as in mammals with the principle exception being the methylation reaction, as generally occurs in mammals, did not appear to occur in plants. The pathway of metabolism in plants thus results in a series of metabolites that substantially differs from that seen in mammals. Nereistoxin appears to predominant in plants and undergoes sulfur oxidation to the oxide (sulfinyl) anddioxide (sulfonyl) and sulfate as well as N-demethylation. Thus, the metabolic pathway in plants appears to result in terminal residues that may be substantially different from those observed in mammals. This difference appears to result from the initial equilibrium established with nereistoxin and dihydronereistoxin both of which follow different pathways in plants and animals to their ultimate degradation (Kodo et al. 1970; Kamesaki et al., 1974; Kamesaki et al., 1976b; 1976c., and Sugita et al., 1978). TOXICOLOGICAL STUDIES Special Studies on Teratogenicity Mice Groups of pregnant mice (CD-1 Strain, 25 mice/group, 24 mice were used at the highest dose level) were administered an aqueous solution of cartap by gavage from day 6 through day 15 of gestation at dosage levels of 0, 10, 25 and 50 mg/kg body weight. The control was administered a volume of 10 ml water/kg body weight. On day 18 of pregnancy each animal was sacrificed and examinations made of viable and nonviable fetuses including an examinations of pre and post-implantation losses. Fetuses were examined for somatic and skeletal abnormalities. Maternal weight gain was slightly depressed at the highest dose level employed, 50 mg/kg/day. There were no differences from control values with respect to post-implantation losses, litter size and fetal abnormalities. Cartap appeared to exert no teratogenic or fetotoxic effects in mice at levels up to and including that which has been shown to have an adverse effect on maternal well-being (Tesh et al., 1976a). Rat In a similar study to evaluate the teratological potential of cartap in the rat, groups of pregnant rats (CD-Strain, 20-22 rats per group), were administered an aqueous solution in cartap at dosage levels of 0, 10, 25 and 50 mg/kg/day from day 6 to day 15 of gestation. Rats were sacrificed on day 21 of pregnancy and again examined for the presence of viable and nonviable fetuses to determine pre-implantation and post-implanation loss. Mortality was observed at the highest level with one dam found dead on day 10 of gestation. There were no apparent effects noted with respect to maternal growth. The average litter size of the treated groups were similar to or greater than those noted in the control. Fetal weight at the highest level of treatment was slightly reduced. Mean fetal weight was also reduced at the two intermediate levels although this reduction was not significant. There were no indications of post-implantation losses. Somatic and skeletal abnormalities, found in treated groups, were not believed to have occurred as a result of the administration of cartap, as they occurred to the same degree in controls. An incidence of subcutaneous edema slightly in excess of that noted in the control group was noted in fetuses of the highest dose group. It was reported that the subcutaneous edema incidence in both the cartap and control group was considerably higher than noted when evaluating a larger control population. It was considered that this effect did not arise from the presence of cartap. A second effect identified as perimeningeal cavitation in a slight excess over that noted with the control was noted of the highest dose group. However, it has been pointed out that perimeningeal cavitation does exist in control animals and the range of this occurrence varies widely. It was also considered that this effect was not attributed to the presence of cartap. A slight reduction in ossification was noted with respect to the size of the interior fontanelle and the number of carpels/tarsels. This effect seemed to correspond to the marginal depression in fetal, weight observed at the high dose level. It was concluded that daily oral administration of cartap through the period of organogenesis at dose levels of 50 mg/kg body weight resulted in a slight reduction in fetal weight and a marginal retardation in development. There was no indication that fetal survival was affected or that malformations were observed (Tesh et al., 1976b). Special Studies on Mutagenesis The mutagenic potential of cartap was evaluated using several strains microorganisms as testor strains. The results of a rec-assay, evaluating DNA damaging capacity in Bacillus subtilis (H-17 and M-45 strains) was negative. Reverse mutation tests, with and without metabolic activation systems using E. coli and Salmonella typhimurium (TA 98, TA 100, TA 1535, TA 1537 and TA 1538) were all negative. A host mediated assay using the G 46 strain J.S. typhimurium in the mouse was also negative (Sherasu et al., 1976). In vivo cytogenetic effects of cartap were examined using bone marrow cells of adult male CF-1 Mice and Wistar rats. There were no increases of chromosomal aberration in cells of rodents treated with a variety of test programs evaluating cartap. These tests include doses of 0, 10, 100 and 150 mg/kg/day to mice or 0, 10 and 100 mg/kg/day to rats administered as a single dose or 5 daily doses. In addition, cartap was administered to weanling male rats orally at 0 or 200 mg/kg/bw or by extraperitoneal injection 0 or 30 mg/kg/bw. In all cases, a positive control of triethylene-melamine (0.5 mg/kg) or furylfuramide (240 mg/kg) was employed. A dominant lethal test was performed where male mice were administered 100 mg/kg/day either as a single or as 5 multiple daily oral doses. All results showed a complete lack of any mutagenic activity under the experimental conditions (Kikuchi, et al, 1976). COMMENTS The 1976 Joint Meeting estimated a Temporary Acceptable Daily Intake for man of 0.05 mg/kg based upon long term studies in two rodent species. Further data required included detailed studies of metabolism, further studies of teratogenic and mutagenic potential and a feeding study in a non-rodent species. Results of additional studies on metabolism in plants and animals and teratogenicity tests were made available. The detailed metabolism studies indicated that Cartap follows a different route of metabolism in plants and animals and it is suggested that selective toxicological studies be conducted on those terminal plant metabolites that differ from the metabolites found in animals. New test data on teratogenic potential of cartap, administered during the full period or organogenesis in mice and rats did not reveal teratogenic activity at doses above the no effect observed level established by the 1976 Joint Meeting. Negative results were obtained in several mutagenicity assays. In view of these new data which reduced concerns expressed at the 1976 Joint Meeting the present meeting was able to estimate an acceptable daily intake. TOXICOLOGICAL EVALUATION Level causing no toxicological effect Rat: 20 mg/kg bw/day Dog: 10 mg/kg bw/day ESTIMATE OF ACCEPTABLE DAILY INTAKE FOR MAN 0-0.1 mg/kg bw RESIDUES IN FOOD AND THEIR EVALUATION Tea Of the two cultural methods for growing tea in Japan, the shade culture expectedly resulted in higher residues than the open-field culture (Table 1). This is due mainly to the unstable nature of cartap in sunlight. Residues ranged from 3.3 to 17.4 mg/kg with the shade culture 10 days after the last application when cartap was applied twice at 1.0 kg a.i./ha. At 14 days after the last application, the residues ranged from 2.7 to 15.0 mg/kg. With single applications, a maximum residue of 14.0 mg/kg was obtained 10 days after the last application. The highest residue obtained under open field condition was 1.4 mg/kg 10 days after the last application when cartap was applied twice. Cartap being water soluble, about 76% of the insecticide is extracted by hot water. Table 1. Comparative residues of cartap hydrochloride in green tea grown in shade or sunlight. (50% soluble powder formulation used) Situation No of Application Rate, Cartap (mg/kg) at intervals (days) after last application trials (kg ai/ha No) 10 14 15 20 21 27 28 Open field 4 1.0 1 0.37 0.56 0.16 (0.48) 0.73 0.81 0.68 0.49 0.6 0.64 (0.42) (0.43) 0.92 1.12 0.57 Shade 4 1.0 1 7.08 6.60 1.66 0.92 (6.87) (6.12) (1.30) (0.97) 1.76 2.31 0.60 0.36 (1.77) (2.37) (0.60) (0.33) 14 8.51 4.26 2.0 (8.3) (5.8) (2.8) (1.4) 3.55 3.96 0.92 0.58 (2.2) (2.5) (0.7) (0.4) Open field 4 1.0 2 1.26 1.12 0.22 (0.97) 0.83 0.52 0.45 (0.71) 0.76 0.64 0.38 (0.52) 1.36 1.84 0.56 Shade 4 1.0 2 9.38 7.40 (8.75) (5.50) 3.30 2.66 (2.45) (2.21) 17.4 15.0 (10.6) (9.1) 6.38 5.64 (4.2) (3.4) Figures in parenthesis are residue equivalent equivalents extracted by hot water FATE OF RESIDUES In animals When cows were fed with 2 and 10 ppm of cartap hydrochloride in the concentrate part of their ration for 30 consecutive days, some indications of a transient accumulation of cartap-derived compounds in milk were observed at the higher feeding level. At the 2 ppm feeding level, the low apparent residues were attributed to analytical interferences since similar levels and frequency of occurrence were also observed in the control group. At the higher feeding level, mean maximum residues of 33 µg/kg were observed after 7 days treatment. There was a subsequent decline of residues and no cartap was detected by the end of the treatment period or during the 30 days recovery period immediately following (Table 2). In muscle and liver, the maximum estimated levels of cartap-derived compounds observed at the end of the treatment period were 18 µg/kg in muscle and 14 µg/kg in liver, expresse as cartap. However, the level in liver could be an over estimate because of interference. No residues could be found in either tissue by the end of the recovery period. In the kidney, the concentration of residues appeared to be related to dietary concentration. At the 2 ppm feeding level, the samples from two animals showed 19 and 33 µg/kg residues at the end of the treatment period and none the end of the recovery period. At 10 the ppm level, the residues were 49 and 41 g/kg at the end of the treatment period declining to 41 and 13 µg/kg, 7 and 30 days respectively after cessation of treatment. No residues were detected in the fat (Table 3). (Takeda 1978a) In plants and soil The absorption and distribution of 35S-labelled cartap hydrochloride in rice plants grown under various hydroponic conditions were studied by autoradiography. After 35S was absorbed from the roots, it was distributed throughout the laminae and high concentrations were observed in the leaf sheaths. Accumulation occurred in the leaf apices. Absorption through the leaf sheaths was also observed, and was found to occur faster in the young leaves than in the older leaves. Distribution occurred through the vascular tissues. When applied to the leaves, the insecticide diffused from the applied region to the leaf apices and accumulated in the leaf sheaths. 35S was detected in the digestive organs, neural tissue and spiracles of the intoxicated rice stem borers (Kodo et al., 1970). In 66-day old rice seedlings, the major region of absorption was observed to be the roots. As much as 15% of the applied 35S-radioactivity was found to have been taken up by the plant, mainly through the roots. As much as 500 mg/kg accumulated in the rice plant seedlings after 6 days immersion (Kamesaki et al 1974). Table 2. Residues in milk of cows fed cartap hydrochloride in the diet. Cartap, mg/kg, at interval(days)after start of feeding Cartap in feed Animal concentrate, ppm number 0 2 4 7 14 22 26 30* 37 51 60 0 3 L T T T T ND ND ND - - - (control) 11 L T ND T ND ND ND ND - - - 15 ND T T ND T ND ND ND ND ND ND 16 ND ND ND I ND ND ND ND ND - - 2 4 ND L ND T T ND T ND - - - 13 ND ND ND ND T T ND ND ND ND ND 17 ND T ND ND T T ND ND ND - - 20 ND ND ND T ND ND ND - - - 10 1 T 0.02 ND 0.04 0.03 0.02 ND ND - - - 6 T T 0.4 0.04 0.03 0.03 ND ND ND ND ND 7 ND L 0.4 0.02 0.03 T T ND - - - 14 ND 0.02 T 0.03 0.02 0.02 ND ND ND - - * End of feeding period All results corrected for 62% recovery. ND denotes "none detected". L denotes "sample lost". I denotes "insufficient sample". - denotes animal sacrificed. T denotes less than 0.015 mg/kg. Table 3. Residues in tissues of cows fed cartap hydrochloride in the diet. Cartap in feed Animal Time of Cartap, mg/kg in concentrate, ppm number sacrifice (days) Kidney Muscle Liver Fat 0 3 30 ND ND T ND (control) 11 30 ND ND T ND 16 37 ND ND T ND 15 60 ND ND T ND Z 4 30 0.02 0.02 0.01 ND 20 30 0.03 NL 0.01 ND 17 37 ND T 0.01 ND 13 60 ND T T ND 10 1 30 0.05 T T ND 7 30 0.04 T 0.01 ND 14 37 0.04 T ND ND 6 60 0.01 T ND ND All results corrected for appropriate recovery. ND denotes "none detected"; T denotes 0.01 mg/kg When paddy cultivation conditions were simulated, 35S-labelled cartap hydrochloride was rapidly absorbed, a maximum level in most tissues being reached after 3 days (Table 4). Metabolism to water-soluble components occurred readily. Accumulation of 35-S in the panicle was also observed (Kamesaki et al., 1976a). It was subsequently found by Kameseki et al., (1976b) that under conventional field practice, the amount of 35S-radioactivity was high in the hull and rice bran but low in the milled rice. Most of the metabolites were water soluble and many were amphoteric. Paper chromatography showed three of the metabolites to have the same Rf values as methionine sulphoxide, methionine sulphone and S-methyl cysteine Sulphoxide. Recently, the formation of seven metabolites was confirmed by Sugita et al., (1978) who proposed the metabolic pathway of cartap in rice shown in Figure 1. In paddy soil, Kamesaki et al., (1976a) found that residues gradually decrease with time but the individual values cannot readily be correlated because the samples were taken from different pots. In water The 35S-radioactivity from labelled cartap hydrochloride rapidly declined after application to simulated paddy water as seen in Table 5 (Kamesaki et al., 1976a). Table 4. Absorption of radioactive components by plant parts. Days after % of applied radioactivity (mean of duplicates) found in application Root Sheath Blade Culm Neck Panicle 1 9.1 27.8 29.5 20.4 4.0 9.3 3 3.6 27.6 48.3 7.1 2.7 10.8 6 5.1 21.8 51.5 5.6 2.8 13.2 13 2.5 18.3 57.5 4.5 1.8 15.4 20 2.1 16.8 54.5 4.0 2.3 20.3 27 3.1 18.2 50.8 4.6 2.9 20.5 34 2.2 19.8 52.1 5.6 2.6 17.6 41 1.5 19.3 54.4 5.4 2.7 16.7 Table 5. 35S radioactivity from labelled cartap hydrochloride in simulated paddy water (x 105 dmp/pot) Days after Average of duplicates application (counts/min. X 10-5) 1 789.5 2 330.9 3 217.6 5 111.8 6 111.4 7 115.1 8 74.2 9 55.6 12 33.5 13 27.3 15 9.3 16 5.7 In processing and cooking The effect of cooking on cartap residues in rice was determined by Inoue (1977). It was found that washing the soaked, air-dried, polished rice before cooking reduced cartap, residues by about one third. No significant reduction in residues was obtained by boiling. METHODS OF RESIDUE ANALYSIS The attention of the Meeting was drawn to difficulties found by some experienced analysts in established laboratories in using the gas chromatographic procedure for cartap. The stability of the reference standards is thought to contribute to the problem. APPRAISAL Cartap was previously evaluated in 1976 (FAO/WHO, 1977b). The manufacturer has submitted additional data in response to the requirements of that meeting. Photodecomposition appears to contribute significantly to the decomposition of the insecticide. This explains the higher cartap, residues found in green tea grown under shade compared to those in plants grown in the open field. In dairy cows, intake results in transient accumulation of the insecticide in milk. Accumulation was also observed in the kidney but not in the liver, muscle or fat.
In rice, diffusion through the roots and leaves occurs with accumulation of the insecticide in the leaf sheathe and panicles. Absorption into the plant was rapid. Degradation in soil and water was also rapid. Seven metabolites, mainly hydrolysis products, were identified in rice plants. Washing rice prior to cooking reduced cartap residues by about one third but no significant reduction was obtained by cooking. Some problems have been reported in analysis by the GLC procedure, probably owing to the unstable nature of the analytical standard. RECOMMENDATIONS With the allocation of an ADI, the previous temporary MRLs are converted to MRLs. The limit for tea is amended as shown. The other tabulated limits were recommended in 1976, but were incorrectly recorded in the text of the 1976 monograph (FAO/WHO, 1977b). They were correctly recorded both in the Annex to FAO/WHO, 1977b and in Annex 1 to the report of the 1976 Meeting (FAO/WHO, 1977a). Commodity MRL (mg/kg) Tea (green, dry) 20 Cabbage 0.2 Chestnuts (seed including pericarp) 0.1 Ginger 0.1 Potatoes 0.1 Rice (hulled) 0.1 Sweet corn 0.1 FURTHER WORK OR INFORMATION Desirable 1. Information on use patterns and residue level in additional food crop for which the compound is used in order to act additional MRLs. 2. Further inter-laboratory information on evaluation of the method of analysis. 3. Short-term feeding studies on terminal plant metabolites that are not found in animals. REFERENCES Fujita T., Y. Shirakawa, K. Iwamoto and K. Konishi. Fate of Cartap (1971) in Animals (II) Investigation of Urinary Metabolites in Rats and Mice. Unpublished report submitted by Takeda Chemical Industries, Ltd. Inoue, M. Effect of Cooking on Cartap Residue. Takeda Chemical Industries, Ltd., Sept. 14 (unpublished). Kamesaki, S., Y. Inoue, K. Konishi Y. Kono, Y. Oshiko and M. Sakai (1974) Fate of Cartap in Plants (II). Absorption and Distribution in Rice Plants (2). Unpublished report submitted by Takeda Chemical Industries, Ltd. Kamesaki, S., K. Konishi, Y. Shirakawa and T. Fujita Fate of Cartap (1976a) in Animals (III). Isolation and Identification of Urinary Metabolites in Rats. Unpublished report submitted by Takeda Chemical Industries, Ltd. Kamesaki, S., Y. Inoue, K. Konishil Y. Kono, Y. Ohiko and M. Sakai (1976b) Fate of Cartap in Plants (III). Distribution and Metabolites in Rice Plants. Unpublished report submitted by Takeda Chemical Industries, Ltd. Kamesaki, S., Y. Inoue, K. Konishi, Y. Kono, Y. Oshiko, M. Sakai (1976c) Fate of Cartap in Plants (IV). Isolation of Metabolites in Rice Plants. Unpublished report submitted by Takeda Chemical Industries, Ltd. Kikuchi, Y., Hitotsumachi, S., Yamamoto, K.I. Mutagenicity Tests (1976) on Cartap hydrochloride. In vitro cytogenetic and dominant lethal tests in mammals. J. of the Takeda Research Laboratories 33: 257-63. Unpublished report submitted by Takeda Chemical Industries, Ltd. Kodo, I., K. Nishi, T. Toga and N. Tan Fate of Cartap in Plants (1970) (I). Absorption and Distribution in Rice Plants (1). Unpublished report submitted by Takeda Chemical Industries, Ltd. Shirasu, Y., Moriya, M. and Watanabe, K. Assessment of the (1976) mutagenicity of cartap hydrochloride by various bacterial test systems. Unpublished report from the Dept. of Toxicology, Institute of Environmental Toxicology submitted by Fabeda Chemical Industries Ltd. Sugita N., A. Takabatake and N. Tan Fate of Cartap In Plants (1978) (V). Primary Metabolites in Rice Plants. Unpublished report submitted by Takeda Chemical Industries, Ltd. to the WHO. Sugita N., A. Takabatake and N. Tan Fate of Cartap in Plants (1978) (V). Primary Metabolites in Rice Plants. Takeda Chemical Industries, Ltd., April 17 (unpublished). Tesh, J.M. S.A. Tesh and M.E. Earthy TA-7 Effects Upon Pregnancy (1976b) in the Rat. Unpublished study from Life Sciences Research submitted by Takeda Chemical Industries, Ltd. Tesh, J.M., S.A. Tesh and M.E. Earthy TA-7 Effects Upon Pregnancy (1976b) in the Rat. Unpublished study from Life Sciences Research submitted by Takeda Chemical Industries, Ltd. Takeda Chemical Industries, Ltd. 7A-7 (Cartap): Milk and Tissue (1978a) Residues following repeated dietary administration to dairy cows over thirty days with a maximum period of thirty days respite from treatment. LSR Report No. 78/TCL8/112 (unpublished). Takeda Chemical Industries, Ltd. Comments to information on the Fate (1978b) of Residue in manufactured Green Tea (unpublished).
See Also: Toxicological Abbreviations Cartap (Pesticide residues in food: 1976 evaluations)