BENALAXYL EXPLANATION Residues of benalaxyl, a systemic fungicide, were evaluated by the JMPR in 1986 (Annex 1, FAO/WHO, 1986e). Toxicological data on benalaxyl is reviewed here. EVALUATION FOR ACCEPTABLE DAILY INTAKE BIOLOGICAL DATA Biochemical Aspects Absorption, Distribution and Excretion Studies reviewed by the 1986 JMPR show that benalaxyl is rapidly metabolized and excreted by rats (Annex I, FAO/WHO, 1986e). Toxicological Studies Special Study on Allergic Sensitisation In the induction phase, groups of 20 female Hartley albino guinea pigs were injected intradermally (0.1 ml) with Freunds Complete adjuvent, p-nitroso dimethylaniline (1%) in petrolatum, mercuric chloride (0.1% in saline) or benalaxyl (5% in paraffin oil). After 7 days, the respective injection sites were treated topically for 48 hours with p-nitroso dimethylalanine (25% in petrolatum), mercuric chloride (1% in petrolatum) and benalaxyl (25% in petrolatum). The animals were subsequently challenged after a further 2 weeks with 5% in petrolatum, mercuric chloride (0.1% in saline) or p-nitroso dimethylnitrosamine (10% in petrolatum) and results scored 24 hours after removal of the patch. Benalaxyl did not induce allergic sensitisation while the positive control, p-nitroso dimethylaniline, gave the expected strong response (Vole Gera and Vasconi, 1981). Special Studies on Carcinogenicity See under long-term studies. Special Studies on Eye and Skin Irritation Table 1. Method Species Route Results Reference Primary eye Rabbit Intraocular Non-irritant Dal Re & Vole irritation Gera (1979a) (Draize Test) Primary skin Rabbit Dermal intact Non-irritant Dal Re & Vole irritation Gera (1979b) (Draize Test) Special Studies on Mutagenicity See Table 2. Special Study on Reproduction Groups of 25 male and 25 female Sprague-Dawely rats received benalaxyl (purity unspecified) in the diet at 0, 100, 1,000 and 5,000 ppm for 112 days before intial mating. Similar treatment was continued throughout two litter and into a second generation which also produced two litters. Dietary exposure to benalaxyl had no effect on parental mortality or on fertility, length of gestation period, litter size or the number of stillborn pups in either the F1 or F2 generations. There was a significant reduction in the bodyweight of high dose F1 males and am irregular reduction for high dose F1, F2A and F2B females. F2B pups of the high-dose group had reduced bodyweights at irregular intervals. At necropsy, the high dose F1 females had significantly increased liver weights whilst F1 rats of both sexes had increased liver to bodyweight ratios. F2B pups had increased liver to bodyweight ratios at 1,000 ppm whilst male and female F2B pups exhibited increased liver to bodyweight ratios at 5,000 ppm. Treatment had no effect on implantation or resorption rates or on the number of corpora lutea. There were no histopathological findings that could be related to treatment. Accordingly, feeding up to 100 ppm benalaxyl in the diet has no effect on the reproduction of rats (Johnson and Becci, 1983). Special Studies on Teratogenicity Rats Groups of 20-23 gravid female Charles River CD (SD) BR rats received by oral gavage 0, 12.5, 50 and 200 mg/kg benalaxyl (95% pure) in methylcellulose (0.5%) from the 6th to 15th day of gestation. Twenty days after mating, the animals were sacrificed and their uterine contents examined. The treatment had no observable effect on the rats and there was no mortality. There were no significant differences in the numbers of implantations, post-implantation losses, numbers of viable fetuses or their sex ratio. No major malformation occurred in any group but there was a dose-related increase in the frequency of minor skeletal anomalies, arising especially from delayed skeletal ossification, which became statistically significant for the mid and high-dose groups. Accordingly, the results of this study indicate that benalaxyl is not teratogenic to rats at daily doses up to 200 mg/kg (Mondino, 1982a). Rabbits Groups of 16 mated female New Zealand White Rabbits received, 0, 5, 50 or 250 mg/kg benalaxyl (purity unspecified, in 1% aqueous methylcellulose) by daily oral gavage from day 6 to 27 of gestation. The animals were sacrificed on day 28 and their uterine contents removed and examined. Seven of the rabbits died during the study, either from intubation error or respiratory disease but these came from all groups in similar numbers. High-dose rabbits lost weight during the last 5 days of the study. At necropsy, the incidences of pregnancy were similar in all groups. Treatment had no effect on the implantation rate or post-implantation losses. The mean number of fetuses and their sex ratios were unaffected but mean litter weight was slightly reduced in the high-dose group. The mean crown-rump length was significantly reduced at 250 mg/kg and slightly reduced at 50 mg/kg. There were no treatment related effects on the rate of minor skeletal defects. The results of this study indicate that 5 mg/kg daily administered of benalaxyl does not affect the fetal development of rabbits (Irvine, 1984). Table 2: Acute Toxicity of Benalaxyl Species Sex Route Purity LD50/LC50 Reference Mouse M/F Oral 92.5% 680 mg/kg Dal Re & Vola Gera, 1981 Rat M/F Oral 96.5% 4,200 mg/kg Dal Re & Vola Gera, 1979c Rat M/F Inhalational ? >10 mg/l Sterner & Pfennig, 1985 Rat M/F Intraperitoneal ? 1,100 mg/kg Dal Re & Vola Gera, 1979d Rabbit M/F Dermal 94% 2,000 mg/kg Vola Gera & Vasconi, 1983 SHORT-TERM STUDIES Mice In a dose-ranging study, groups of 20 male and 20 female Swiss mice received benalaxyl (94% pure) in their diet at 0, 500, 1,000, 2,000, 3,000 and 5,000 ppm for 90 days. There were no apparent effects on the behaviour, bodyweight, food and water consumption or animal mortality. Half of the mice of each group and sex were sacrificed at 40 days for interim evaluation. At necropsy, there was a dose-related increase in absolute and relative liver weights which occurred at and above 1,000 ppm at 96 days and at and above 2,000 ppm at 42 days, especially in female mice. Histopathology showed no significant differences between treated and control groups (Maltoni, 1985). Rats Groups of Charles River CD(SD) BR rats (20 per sex per group) were fed benalaxyl in the diet at levels of 0, 10, 100, 1000 and 10000 ppm for 13 weeks. A further group (20 per sex) were fed benalaxyl in the diet at a level of 12000 ppm for 4 weeks followed by a recovery period of 4 weeks with no chemical in the diet. Observations included clinical signs, food consumption, body weight, organ weight, hematology, urinalysis, gross and microscopic pathology. There were no treatment related deaths during the study. One animal in the recovery group died subsequent to blood sampling which was performed by incision of a sublingual vein under light ether anaesthesia at 0, 5 and 13 weeks. There were no clinical signs of treatment. Body-weight gain was reduced slightly between weeks 2 and 13 at the 10000 ppm level, and during the treatment period at the 12000 ppm level. Slight anemia was seen after 5 weeks in females and males at the 12000 ppm level, but values returned to normal during the recovery period. Serum cholesterol was increased after 5 and 13 weeks in males and females at 10000 ppm. In the recovery groups fed 12000 ppm, cholesterol was elevated at 5 weeks but normal by 13 weeks. Liver weight was increased at the 1000 and 10000 ppm levels in a dose related manner. At necropsy the evidence of "lobulated" liver was increased at the 10000 ppm level in males. Diffuse hepatic steatosis was observed in both sexes at this dose level, but was not seen at sacrifice in the recovery group. There were no other treatment related histopathological findings. Pituitary adenomas were found in one female at both the 10 and 100 ppm levels. The study indicated that feeding of benalaxyl at dietary levels up to 100 ppm (5 mg/kg b.w./day) is without toxicological effect in rats (Mondino, 1982b). Dogs Groups of 6 male and 6 female Beagle dogs received benalaxyl (92.5% pure) in the diet at 0, 10, 200 and 800 ppm for 52 weeks. There were no mortalities and no signs were observed that could be related to treatment. Ophthalmoscopy, performed at the beginning and at termination of exposure, was unremarkable. Treatment had no effect on food consumption or bodyweight gain. Hematological and clinical chemical parameters and urinalysis, investigated at regular intervals throughout the exposure, showed no consistent effects and none that were related to treatment. At necropsy, there were no remarkable gross pathological findings. Histopathology showed atrophy of the seminiferous tubules of two high-dose dogs that was not seen in any other group. Accordingly, the results of this study indicate that feeding up to 200 ppm in the diet is without observable effect in dogs (Mondino, 1982c). LONG-TERM STUDIES Mice Groups of 60 male and female Swiss mice received benalaxyl (94% pure) in their diets at 0, 250, 1,000 and 3,000 ppm for 78 weeks. Benealaxyl exposure had no effect on the survival of female mice but reduced the survival of males treated at 1,000 and 3,000 ppm. The body weight of treated male groups tended to be less than controls, but there was no association with dietary concentration of benalaxyl. Treatment had no observable effect on behaviour or appearance. Clinical chemistry and hematological parameters were not influenced by treatment. At necropsy, the absolute and relative liver weights of female mice exposed to 3,000 ppm benalaxyl was increased. Widespread amyloidosis, affecting adrenal and salivary glands, kidney, liver, spleen, stomach, intestine and Zymbal gland, was found more commonly in treated than control mice, especially mid and high dose males. There was also an association between the amyloidosis and benalaxyl exposure in those male mice which died spontaneously during the study. Three high dose male mice were found to have transitional cell carcinoma of the urinary bladder which was not seen in other groups. There were no significant increases in other tumour types in any group. Due to the increased incidence of amyloid deposition in all treated groups, this study did not establish a clear no-effect level (Maltoni, 1985). Rats Groups of Charles River CD(SD) BR rats (65 per sex per group) were fed benalaxyl (purity unstated) in the diet at levels of 0, 4, 100 and 1000 ppm for 104 weeks. A separate group of 30 rats per sex were used for the 'pre-study' clinical testing programme. Animals were given fresh diet each week and each batch was analysed for benalaxyl content. All animals were observed daily for clinical symptoms of toxicity. Body weight and food consumption were measured weekly for 14 weeks and twice weekly thereafter. Blood samples for clinical chemistry and hematology were collected at 0, 3 (hematology only), 6, 12, 18 and 24 months. Urinalysis were performed at 12, 18 and' 24 months; ophthalmological examinations were performed at 0, 1, 6, 12, 18 and 24 months. An interim sacrifice (10 rats/sex/group) was made at 12 months. All animals except the 'pre-study' clinical testing group were subject to gross necropsy and histopathological examination. Organ weights were determined for brain, heart, kidneys, liver, ovaries, testes and thymus. No clinical signs of toxicity were apparent during the study. Mortality was not treatment related; survival at 104 weeks ranged from 34 to 53%. There were no effects of treatment on body weight or food consumption. Hematology, clinical chemistry, urinalysis and ophthalmoscopy were unremarkable. There were no treatment related effects on organ weights, and there was no gross or microscopic pathology. The study demonstrated no toxic effects of treatment of rats with benalaxyl at levels up to 1000 ppm in the diet (equivalent to 50 mg/kg b.w./day) (Thompson et al., 1983). Special Studies on Mutagenicity Table 2 summarizes the results of mutagenicity testing of benalaxyl. Table 2. Special Studies on Mutagenicity Test System Test Object Concentrations Purity Results References Ames test (with and Salmonella typhimurium 200, 400, 800, 98% Negative de Carneri, 1979a without metabolic TA1535, TA1537, TA1538, 1600 ug/plate (1) activation) TA98, TA100 Gene mutation Schizosaccharomyces 20, 40, 80, ? Negative de Carneri, 1980 (without metabolic pombe P1 (Sp 198, 100 ug/ml (2) activation) (with ade 6-60 metabolic radio-198, h) 100, 200, 400, Negative activation) 800 ug/ml (3) Gene mutation Chinese Hamster 3 × 10-7, 10-6, ? Negative Monaco, et al., (without metabolic V79 Cells 3 × 10-6, 10-5, (3) 1983 activation) (with 3 × 10-5 M metabolic Negative activation) (6) Gene conversion Saccharomyces 8, 40, 200, ? Negative de Carneri, 1979b (with and without cerevisae D4 1000 ug/ml (2) metabolic activation) Chromosome Chinese Hamster 1000, 2000, ? Negative Mondino, 1980a Abberation Ovary Cells 4000 mg/kg (5) Chromosome Cultured human Mondino, 1980b aberration lymphocytes (without metabolic 0.083, 0.25, ? Negative activation) (with 0.83, 2.5 mg/ml (5) metabolic 0.033, 0.1, Negative activation) 0.033, 1 mg/ml (7) Table 2. contd. Test System Test Object Concentrations Purity Results References Primary Rat Rat Hepatocytes 0.5, 1.0 94% Negative Myhr and Brusick, 1983 Hepatocyte Unsheduled DNA 2.5, 5, 10, 25, Synthesis 50 ug/ml (1) Positive controls, N-methyl-N-nitro-N-nitrosoquanidine, 2-nitrofluorene and 2-acetylaminofluorine (2-AAF) gave expected positive result. (2) Positive control, methyl methanesulphonate, gave expected positive result. (3) Positive control, N-dimethylnitrosamine, gave expected positive result. (4) Positive control, cyclophosphamide, gave expected positive result. (5) Positive control, Mitomycin C, gave expected positive result. (6) Positive control, ethanemethanesulphonate, gave expected positive result. (7) Positive control, phenacetin, gave expected positive result. (8) Positive control, 2-AAF gave expected positive result. COMMENTS Benalaxyl was evaluated toxicologically for the first time by the present meeting. It was evaluated by the 1986 JMPR for residues only. As noted at that time, benalaxyl is completely metabolized and does not accumulate in the tissues of rats. Comprehensive short- and long-term dietary administration indicates that the toxicity of benalaxyl is low. Hepatic enlargement occurred in rats fed benalaxyl (> 1000 ppm) in their diet for 14 weeks and in mice fed for 78 weeks (3000 ppm). However, hepatomegaly did not occur in rats fed benalaxyl (1000 ppm) for two years or in dogs fed for one year (800 ppm). The meeting concluded that although the hepatic enlargement observed in rodents was of questionable toxicological significance, it could be used to establish a no-effect level and estimate an ADI. TOXICOLOGICAL EVALUATION LEVEL CAUSING NO TOXICOLOGICAL EFFECT Mouse: 500 ppm in the diet, equivalent to 75 mg/kg bw/day. Rat: 100 ppm in the diet, equal to 5 mg/kg bw/day. Dog: 200 ppm in the diet, equal to 7 mg/kg bw/day. ESTIMATE OF ACCEPTABLE DAILY INTAKE FOR MAN 0-0.05 mg/kg bw. STUDIES WHICH WILL PROVIDE INFORMATION VALUABLE IN THE CONTINUED EVALUATION OF THE COMPOUND Observations in man. REFERENCES de Carneri, I., 1979a. Microbiological Mutagenesis Study on CRA 109 (M9834). Genetic mutation test in Salmonella typhimurium (Ames). Farmitalia Carlo Erba Research and Development. Unpublished study submitted to WHO by Farmoplant Research and Development. de Carneri, I., 1979b. Microbiological Mutagenesis Study on CRA 109 (M9834). DNA damage and repair test (Mitotic gene conversion in Saccharomyces cerevisae D4). Farmitalia Carlo Erba Research and Development. Unpublished study submitted to WHO by Farmoplant Research and Development. de Carneri, I., 1980. Microbiological Mutagenesis Study on CRA 109 (M9834). In vitro gene mutation test in Schizosaccharomyces pombe P1. Farmitalia Carlo Erba Research and Development. Unpublished study submitted to WHO by Farmoplant Research and Development. Dal Re, U. & Vola Gera, F., 1979a. Primary eye irritation study of M9834 in albino rabbits. Montedison Division Agricoltura. Centro Ricerche Antiparassitari. Unpublished study submitted to WHO by Farmoplant Research and Development. Dal Re, U. & Vola Gera, F., 1979b. Primary skin irritation study of M9834 in albino rabbits. Montedison Division Agricoltura. Centro Ricerche Antiparassitari. Unpublished study submitted to WHO by Farmoplant Research and Development. Dal Re, U. & Vola Gera, F., 1979c. Acute oral toxicity study of M9834 in albino rat. Montedison Division Agricoltura. Centro Ricerche Antiparassitari. Unpublished study s Submitted to WHO by Farmoplant Research and Development. Dal Re, U. & Vola Gera, F., 1979d. Determination of the acute intraperitoneal toxicity of M9834, technical grade, in the rat. Montedison S.p.A. Agricultural Division, Pesticide Research Centre, Milan. Unpublished study submitted to WHO by Farmoplant Research and Development. Dal Re, U. & Vola Gera, F., 1981. Determination of the acute oral toxicity of Galben, technical grade, in albino mice. Gruppo Montedison S.p.A. Pesticide Research Centre, Milan. Unpublished study submitted to WHO by Farmoplant Research and Development. Irvine, L.F.H., 1984. Galben: Oral (Gavage) teratology Study in the New Zealand White Rabbit. Hazleton Laboratories Europe Ltd Report No. 3596-309/3. Unpublished study submitted to WHO by Farmoplant Research and Development. Johnson, W.D. & Becci, P.J., 1983. Two generation Reproduction Study in Rats with Galben Technical (Final Report). Food and Drug Research Laboratories, Inc. Waverly Study No. 7220. Unpublished study submitted to WHO by Farmoplant Research and Development. Maltoni, C., 1985. Evaluation of Chronic Toxicity and Oncogenic Potential of Galben (R) (CAS no. 71626-11-4) in Swiss Mice (Oral Dosing Study). Bologna Institute of Oncology Study No. BT 5004. Unpublished study submitted to WHO by Farmoplant Research and Development. Monaco, M., Forster, R. & Nunziata, A., 1983. Gene mutation in Chinese Hamster V798 Cells Test substance: Galben TH. Life Sciences Research, Roma toxicology Centre Rep. No. LSR-RTC FMP 001. Unpublished study submitted to WHO by Farmoplant Research and Development. Mondino, A., 1980a. In vivo Study of the Induction of Chromosome Aberrations in the Chinese Hamster by Compound M 9834 Administered Orally. Institute of Biomedical Research Antoine Marxer S.p.A. Ivrea. Unpublished study submitted to WHO by Farmoplant Research and Development. Mondino, A., 1980b. In vitro Study of the Induction of Chromosome Aberrations by Compound M 9834 in Human Lymphocyte Cultures. Institute of Biomedical Research Antoine Marxer S.p.A. Ivrea. Unpublished study submitted to WHO by Farmoplant Research and Development. Mondino, A., 1982a. Teratogenesis study of the product M 9834 in Charles River CD (SD) rats on oral administration from the 6th to 24th day of gestation, at daily doses of 12.5, 50 and 200 mg/kg. Antoine Marxer Institute of Biomedical Research, Ivrea. Unpublished study submitted to WHO by Farmoplant Research and Development. Mondino, A., 1982b. 13-Week Oral Subacute Toxicity study of the Product M 9834 (Galben) administered to Charles River CD (SD) BR rats in the diet, at the doses of 10, 100, 1000, 10,000 and 12,000 ppm. Institute of Biomedical Research 'Antoine Marxer', S.p.A. Ivrea. Unpublished study submitted to WHO by Farmoplant Research and Development. Mondino, A., 1982c. Long term toxicity study with repeated oral administration of the product M 9834 (Galben) added to the food of Beagle dogs for 52 weeks, at the dosage levels of 10, 200 and 800 ppm. Antoine Marxer Institute of Biomedical Research, Ivrea. Unpublished study submitted to WHO by Farmoplant Research and Development. Myhr, B.C. & Brusick, D.J., 1983. Evaluation of Galben in the Primary Rat Hepatocyte Unscheduled DNA Synthesis Assay. Final Report, Litton Bionetics Project No. 20991. Unpublished study submitted to WHO by Farmoplant Research and Development. Sterner & Pfennig, 1985. Acute Inhalation Toxicity of 'Galben Th' in Rats. IBR Forschungs GmBh, Walsrode Proj. No. 1-4-549-81. Unpublished study submitted to WHO by Farmoplant Research and Development. Thompson, S.W., Davidson, T.J. & Becci, P.J., 1983. Lifetime Oral Dosing Studies in Rats: Combined Oncogenicity and Chronic Toxicity of Galben Technical 9834. Food and Research Laboratories, Inc. Report No. 6568-11 (Final Report). Unpublished study submitted to WHO by Farmoplant Research and Development. Vola Gera, F. & Vasconi, F., 1981. Allergic contact sensitisation test on albino guinea pig using the maximisation test: evaluation of the allergenic potency of Galben. Farmoplant Centro Ricerche Antiparassitari Biological Evaluation Department, Milan. Unpublished study submitted to WHO by Farmoplant Research and Development. Vola Gera, F. & Vasconi, F., 1983. Galben Acute Dermal Toxicity Study (LD50) in the Albino Rabbit. Limit Test. Farmoplant Centro Ricerche Antiparassitari Biological Evaluation Department, Milan. Unpublished study submitted to WHO by Farmoplant Research and Development.
See Also: Toxicological Abbreviations Benalaxyl (JMPR Evaluations 2005 Part II Toxicological)