TEBUFENOZIDE First draft prepared by D. Grant & S. Ma Pesticide Evaluation Division, Health Evaluation Division, Health Canada, Tunney's Pasture, Ottawa, Ontario, Canada Explanation Evaluation for acceptable daily intake Biochemical aspects Absorption, distribution, and excretion Biotransformation Toxicological studies Acute toxicity Short-term toxicity Long-term toxicity and carcinogenicity Reproductive toxicity Developmental toxicity Genotoxicity Special studies Dermal and ocular irritation and dermal sensitization Neurotoxicity Studies on metabolites Comments Toxicological evaluation References Explanation Tebufenozide, 4-ethylbenzoic acid- N'-tert-butyl- N'-(3,5-di- methylbenzoyl)hydrazide, is a fat-soluble insecticide used to control Lepidoptera pests in fruits, vegetables, and other crops. It has a novel mode of action, in that it mimics the action of the insect moulting hormone, ecdysome. Lepidoptera larvae cease to feed within hours of exposure to tebufenozide and then undergo a lethal unsuccessful moult. Tebufenozide was evaluated for the first time by the present Meeting. Evaluation for acceptable daily intake 1. Biochemical aspects (a) Absorption, distribution, and excretion Three groups of four male and four female Crl:CD BR rats were fasted overnight and then given a single dose by gavage of 250 mg/kg bw of either [14C- tert-butyl]tebufenozide, [14C-A-ring]-tebufenozide, or [14C-B-ring]tebufenozide. The profile of excretion of radiolabel by males and females was similar. Absorption and excretion of 14C label were rapid, with > 70% of the administered dose eliminated within 48 h. The mean total excreted over seven days was > 82%. Faeces was the major route of excretion, representing at least 98% of the total radiolabel excreted; only minor amounts (1-2% of dose) were excreted in the urine and trace amounts (< 0.05% of dose) in expired air as 14C-carbon dioxide or volatile organic compounds. Little radiolabel was retained in organs or tissues by seven days after dosing: < 0.1% of the [14C- tert-butyl]-labelled material, < 0.03% [14C-A-ring]tebufenozide, and < 0.01% [14C-B-ring]-tebufenozide. The highest tissue concentrations were found in the liver, blood, spleen, and fat (0.5-1.3 µg/g 14C-tebufenozide equivalents) of animals given [14C- tert-butyl]- labelled material and in the fat (< 1 µg/g) of animals given [14C-A-ring]-tebufenozide. The concentrations of radiolabel in the tissues of animals given [14C-B-ring]tebufenozide were near or below the limit of detection (0.4 ppm) (LeVan, 1991). Four male and four female Crl:CD BR rats received a bile-duct cannula, were fasted overnight, and were then given a single dose of 3 mg [14C- tert-butyl]tebufenozide/kg bw by gavage. The absorption and elimination of radiolabel were followed up to 72 h. No significant difference in the excretion profile was seen between males and females. The absorption and excretion of radiolabel were rapid, and about 100% of the administered dose was recovered in excreta within 24 h. Most of the radiolabel (67-70%) was unabsorbed and was eliminated directly in the faeces. Systemic absorption was calculated to be 35-39% of the total administered dose; 30-34% was excreted in the bile and approx. 5% in the urine. Tissue retention of radiolabel was very low, with a mean of 0.3-0.4% remaining in the carcass 72 h after dosing (Struble & Hazelton, 1992a). Groups of three to six male and female Crl:CD BR Sprague-Dawley rats were given a single dose of either [14C- tert-butyl]-tebufenozide, [14C-A-ring]tebufenozide, or [14C-B-ring]-tebufenozide by gavage at nominal doses of 3 or 250 mg/kg bw. One group of animals was fed a diet containing 30 ppm nonradioactive tebufenozide for two weeks before receiving a single oral dose of 3 mg/kg bw [14C- tert-butyl]- tebufenozide. The absorption and excretion of the radiolabel were very rapid. The excretion profiles were similar, regardless of the position of the 14C label, the dose, the sex of the rat, or whether the animals were pretreated with tebufenozide. A mean total of 87-104% of the administered dose was excreted within 48 h of dosing, primarily via the faeces, which accounted for > 90% of the radiolabel excreted; only minor amounts (< 1-8% of the dose) were excreted in the urine. Trace amounts of radiolabel (< 0.1-0.4% of the dose) were recovered as carbon dioxide and volatile organic compounds in the expired air of rats dosed with [14C- tert-butyl]tebufenozide but not from rats dosed with the A-ring or B-ring label. Maximal levels of radiolabel were measured in the blood 0.5-12 h after dosing. Clearance of the A-ring and B-ring labels from the circulation was very rapid, such that no 14C was detected in blood 24 h after dosing. In contrast, disappearance of radiolabel from the blood of animals given the tert-butyl label was relatively slow, low levels being detected 10 days after dosing. The peak concentration of radiolabel in blood was not proportional to the dose administered, suggesting that the pharmacokinetics of 14C-tebufenozide are not linear between the low (3 mg/kg bw) and high (250 mg/kg bw) doses. Tissue retention of radiolabel was very low; by 168 h after treatment, the mean totals of the administered dose retained were < 1, < 0.2, and < 0.01% of the tert-butyl, A-ring, and B-ring labels, respectively, at 3 mg/kg bw and < 0.01% of any of the three labels at 250 mg/kg bw. The highest concentrations of radiolabel were consistently found in the liver, fat, and kidneys; all other tissues contained < 0.01 ppm or undetectable levels, regardless of the position of the label, the dose, or the sex of the rat. The distribution in the tissues was consistent with the pharmacokinetic data and indicated that the 14C associated with the A-ring and B-ring labels was cleared more rapidly from the tissues than that associated with the tert-butyl label (Struble & Hazelton, 1992b). (b) Biotransformation Groups of Crl:CD BR Sprague-Dawley rats were given [14C- tert-butyl]-, [14C-A-ring]-, or [14C-B-ring]tebufenozide by gavage at a dose of 3 mg/kg bw or [14C- tert-butyl]- or [14C-B-ring]- tebufenozide at 250 mg/kg bw. Faeces and urine were collected from five rats of each sex per group and analysed for tebufenozide metabolites. Parent tebufenozide was the major component present in the faeces, accounting for > 90% of the administered dose at the high dose and > 35% at the low dose. Eleven metabolites were identified in the faeces of animals at the high dose and 14 in faeces from those at the low dose; 10 of the metabolites were common to the two groups. No qualitative difference in metabolite profile was seen with the differently labelled versions of tebufenozide. No parent tebufenozide was found in the urine, but many of the metabolites were the same as those found in the faeces. An additional two or three unknown metabolites, representing 3-3.5% of the total dose, were found in acidified fractions of urine from animals given A- or B-ring labelled material. These were probably partially fragmented metabolites of tebufenozide in which the tert-butyl group had been metabolically cleaved. The faecal and urinary analyses thus indicate a total of 15 metabolites (all except one present at < 1% of the dose) in excreta from animals at the high dose and 14 metabolites (two present at > 10% and nine at > 1% of the dose) in excreta from animals at the low dose. The extent of metabolism of tebufenozide was highly dependent on the amount of test material administered. Thus, only about 4% of the high dose was metabolized, producing about 10 mg/kg bw of metabolites, whereas about 46% of the low dose was metabolized, producing about 1.4 mg/kg bw of metabolites. The major route of metabolism of tebufenozide appeared to be oxidation of benzylic carbons (A or B ring) to provide a number of oxidized metabolites with various combinations of oxidation states at the 3-carbon centres. One exception was RH-2703 (see Figure 1), which was produced by oxidation of the non-benzylic terminal carbon on the A-ring ethyl group. A metabolic pathway for tebufenozide in rats was proposed (Figure 1) (Hawkins et al., 1992). The metabolism of tebufenozide was studied in Crl:CD BR Sprague-Dawley rats given a single dose of 3 mg/kg bw of [14C- tert- butyl]tebufenozide by gavage. One group was fed 30 ppm of non- radioactive tebufenozide in the diet for two weeks before receiving the radiolabelled material. Faeces and urine from five males and five females were collected and analysed for tebufenozide metabolites. The parent tebufenozide was a major component of faeces, accounting for 26-39% of the administered radiolabel, and 13 metabolites were identified. Significant differences between males and females in the levels of several metabolites were noted: the major faecal metabolites were RH-0282, RH-120898, and RH-0126 in animals of each sex and RH-122777 in females only. No parent tebufenozide was found in the urine, but many of the 13 metabolites found were the same as those in faeces. No significant qualitative differences in the metabolism of 14C-tebufenozide were found between rats pretreated with 30 ppm dietary tebufenozide and those receiving the single 14C-radiolabelled dose without pretreatment. Quantitatively, slightly less parent tebufenozide was found in the excreta of pulse-dosed than those of single-dosed animals, suggesting that slightly more tebufenozide metabolism occurred in the former, which also had generally higher levels of the more highly oxidized metabolites in their excreta (Hawkins et al., 1993).Groups of Crl:CD BR Sprague-Dawley rats received a bile-duct cannula and then a single oral dose of 3 mg/kg bw [14C- tert-butyl]- tebufenozide. Bile samples collected from one male and one female rat during 0-6 h after treatment, representing about 70% of total biliary excretion of radiolabel over 72 h, were analysed for tebufenozide metabolites. No parent compound was found; 13 biliary metabolites were identified, and five unknown metabolites were isolated. In general, the biliary metabolites were identical to those in the faeces and urine, but three new metabolites were observed: [A-ring]-ketone- [B-ring]-diol, RH-122652, and RH-2652. The last two were also identified by mass spectroscopy in the faeces but at levels too low for quantification. The unknown metabolites in bile appeared to be high-molecular-mass amino-acid conjugates of acidic tebufenozide metabolites. It was postulated that these conjugates are metabolized in rats before excretion in order to recover the amino acids; hence, their absence in faeces (Hawkins & Hazelton, 1993). 2. Toxicological studies (a) Acute toxicity The results of studies of the acute toxicity of tebufenozide are summarized in Table 1. Tebufenozide was of low toxicity to mice and rats when given orally, dermally, or by inhalation. No deaths or clinical signs of systemic toxicity were observed at doses < 5.0 g/kg bw. Dermal administration resulted only in transient, mild local erythema at the site of application. After inhalation, accumulation of red-brown material was seen around the nose, mouth, and eyes, sometimes with a purulent anogenital discharge which lasted for one to three days. (b) Short-term toxicity Mice Six groups of eight male albino Crl:CD-1 ICR BR mice were fed diets containing technical-grade tebufenozide (purity, 94%) to provide doses of 0, 60, 200, 600, 2000, or 6000 ppm, equal to 0, 12, 39, 97, 350, or 1100 mg/kg bw per day, for two weeks. At the highest dose, the absolute and relative liver weights were significantly increased, but, in the absence of histopathological data, the toxicological significance of this change could not be fully evaluated. The NOAEL was 600 ppm, equal to 97 mg/kg bw per day, on the basis of the increased relative liver weights (Kyle, 1992). Table 1. Acute toxicity of tebufenozide in experimental animals Species Sex Route LD50 (mg/kg bw) Reference or LC50 (mg/litre) Mouse Male, female Oral > 5000 Morrison & Hamilton (1991a) Rat Male, female Oral > 5000 Morrison & Hamilton (1991b) Rat Male, female Dermal > 5000 Morrison & Hamilton (1991c) Rat Male Inhalation > 4.3 Ulrich (1992) Female > 4.5 Groups of 10 male and 10 female Crl:CD-1 ICR BR VAF/Plus mice were fed diets containing technical-grade tebufenozide (purity, 98.6%) providing levels of 0, 20, 200, 2000, or 20 000 ppm, equal to 0, 3.4, 35, 340, and 3300 mg/kg bw per day for males and 0, 4.3, 45, 430, and 4200 mg/kg bw per day for females, for 13 weeks. At 200 ppm, slightly reduced mean body-weight gain (but not overall body weight) was seen in males and a marginally higher incidence of increased extramedullary haematopoiesis in the spleen and pigment accumulation in kidney tubules (with no concomitant changes in haematological parameters) in females; these changes were considered not to be toxicologically significant. At 2000 and 20 000 ppm, significant haemolytic changes and a reduced mean myeloid:erythroid ratio in bone marrow were seen, with dose-related increases in the absolute and relative (to body and to brain) weights of the spleen and liver. Histopathological examination revealed an increased incidence and/or severity of pigment deposition in the liver, spleen, and kidney tubules and increased extramedullary haematopoiesis in the spleen. The pigment was characterized as bile in the liver and haemosiderin in the liver, spleen and kidney. The primary target of tebufenozide was the erythrocyte, causing increased erythrocyte turnover and compensatory responses from the haematopoietic tissues. The NOAEL was 200 ppm, equal to 35 mg/kg bw per day (Osheroff, 1991a). Rat Groups of six male and six female Crl:CD BR rats were given technical-grade tebufenozide (purity, 94%) in the diet to provide levels of 0, 50, 250, 1000, 2500, or 10 000 ppm, equal to 0, 3.8, 19, 71, 180, and 700 mg/kg bw per day for males and 0, 4.5, 21, 85, 210 and 780 mg/kg bw per day for females, for two weeks. The relative weight of the liver was increased in males and the absolute and relative weights in females at 1000 ppm; however, in the absence of histopathological data, the toxicological significance of these changes could not be fully evaluated. At 10 000 ppm, slight reductions in body-weight gain, food consumption, and erythrocyte parameters were seen, which were within the normal range of biological variations and were considered to be of minimal toxicological significance. At this dose, increased absolute and relative spleen weights were observed in males and females; however, in the absence of histopathological data, the significance of these changes could not be evaluated. The NOAEL was 250 ppm, equal to 19 mg/kg bw per day, on the basis of the changes in liver weight (Kyle & Quinn, 1992). In a range-finding study, groups of 10 male and 10 female Crl:CD BR Sprague-Dawley rats were given diets containing technical-grade tebufenozide (purity, 96.4%) to provide levels of 0 or 20 000 ppm, equal to 0 and 1500 mg/kg bw per day in males and 0 and 1600 mg/kg bw per day in females, for four weeks. Decreases in body weight (< 9%), body-weight gain, and food consumption (< 12%) were observed, but the mean efficiency of food use was not affected, suggesting reduced palatability of the 20 000-ppm test diet. Slight reductions in erythrocyte count, haemoglobin, and haematocrit were seen. The absolute and relative liver weights of animals of each sex, the absolute and relative spleen weights of males, and the relative kidney weights of females were higher in the treated rats, but, in the absence of histopathological data, the toxicological significance of these changes could not be fully assessed. It was concluded that the high dietary level of 20 000 ppm could be used in studies of short- term toxicity in rats (Osheroff, 1991b). Groups of 10 male and 10 female Crl:CD BR rats were fed diets containing technical-grade tebufenozide (purity, 96.4 or 98.6%) in the diet to provide levels of 0, 20, 200, 2000, or 20 000 ppm, equal to 0, 1.3, 13, 130, and 1300 mg/kg bw per day for males and 0, 1.6, 16, 160, and 1600 mg/kg bw per day for females, for 13 weeks. The dose of 2000 ppm induced significant decreases in overall body-weight gain and mean food consumption during the first four weeks of dosing and an increase in the relative (to brain) weight of the liver in females. Slight haemolytic anaemia, increased bone-marrow erythropoiesis (decreased mean myeloid:erythroid ratio), and increased deposition of pigment in the spleen were observed. At the highest dose, additional treatment-related effects included overt haemolytic changes, slightly elevated absolute and relative (to brain) spleen weights in animals of each sex, elevated absolute liver weight in females, and tubular nephrosis of the kidney in four males. The NOAEL was 200 ppm, equal to 13 mg/kg bw per day (Osheroff, 1991c). Groups of six male and six female Crl:CD BR rats received applications of technical-grade tebufenozide (purity, 97.2%) moistened with 0.9% saline (1:6 w/v) at a dose of 1000 mg/kg bw per day on the shaved, intact skin of the back under semi-occlusive bandages for 6 h per day, five days per week for four weeks (a total of 21 applications). No signs of treatment-related systemic toxicity or dermal irritation were observed. The NOAEL was thus 1000 mg/kg bw per day (Morrison et al., 1993). Dogs Five groups of four male beagle dogs received diets containing technical-grade tebufenozide (purity, 96.8%) at 0, 150, 600, 2400, or 9600 ppm, equal to 0, 5, 19, 77, and 290 mg/kg bw per day, for two weeks. A significant increase in the mean spleen weight was seen in animals at 600 ppm. At 9600 ppm, mild haemolytic anaemia (significantly reduced erythrocyte count, haemoglobin, and haematocrit) was observed. The NOAEL was 150 ppm, equal to 5 mg/kg bw per day (Kehoe, 1990). Two groups of four male beagle dogs were fed diets containing technical-grade tebufenozide (purity, 97.5%) at 0 or 1500 ppm, equal to 42 mg/kg bw per day, for six weeks. All animals were then maintained on the basal diet for a four-week recovery period, after which the study was terminated. Haematological examinations were performed on all dogs before treatment and at 6, 8, and 10 weeks. Administration of 1500 ppm resulted in mild regenerative anaemia, but total recovery had occurred four weeks after cessation of treatment (Yoshida, 1992). Groups of four male and four female beagle dogs received diets containing technical-grade tebufenozide (purity, 96.1%) at 0, 50, 500, or 5000 ppm, equal to 0, 2.1, 20, and 200 mg/kg bw per day for males and 0, 2, 21, and 200 mg/kg bw per day for females, for 90 days. Animals of each sex at 500 ppm had an increased incidence of Heinz bodies, and females at this dose had an elevated mean total bilirubin level and increased absolute and relative spleen weights. Histopathological examination revealed an increased incidence of pigment deposition (haemosiderin) in the Kupffer cells of the liver and increased haematopoiesis and sinusoidal engorgement of the spleen. At the highest dose, significant haemolytic changes and increased bone-marrow erythropoiesis (reduced mean myeloid:erythroid ratio) were seen at weeks 6 and 13 of treatment. The mean total plasma bilirubin level was elevated in animals of each sex, and bilirubin was present in the urine of three males. Increased absolute and relative spleen weights and slightly higher relative liver weights were observed. Increased incidences of pigment deposition (haemosiderin) and the presence of erythrocytes in some Kupffer cells of the liver suggested active erythrophagocytosis. Increased splenic haematopoiesis, splenic sinusoidal engorgement, and bone-marrow hyperplasia were also noted. The primary target of tebufenozide in the dog was the erythrocytes, leading to mild haemolytic anaemia and compensatory responses from the haematopoietic tissues. The NOAEL was 50 ppm, equal to 2 mg/kg bw per day (Clay, 1992). Groups of four male and four female beagle dogs were fed diets containing technical-grade tebufenozide (purity, 97.5%) providing dietary levels of 0, 15, 50, 250, or 1500 ppm, equal to 0, 0.6, 1.8, 8.7, or 53 mg/kg bw per day for males and 0, 0.6, 1.9, 8.9, and 56 mg/kg bw per day for females, for 52 weeks. In animals at 250 ppm, slight but consistent haemolytic changes and a slightly elevated total plasma bilirubin level were seen, the latter especially in females, over the 52-week period. The mean absolute and relative spleen weights of females and the mean relative liver weight of males were increased, and an increased incidence of pigment deposition in the Kupffer cells of the liver, increased splenic haematopoiesis and sinusoidal engorgement, and bone-marrow hyperplasia were also observed. Similar treatment-related effects of increased magnitude and severity were observed at the highest dose. The primary target of tebufenozide was thus erythrocytes, leading to mild peripheral haemolytic anaemia and compensatory responses from the haematopoietic tissues. The NOAEL was 50 ppm, equal to 1.8 mg/kg bw per day (Richards, 1992). (c) Long-term toxicity and carcinogenicity Mice Groups of 50 male and 50 female Crl:CD-1(ICR)BR mice received diets containing technical-grade tebufenozide (purity, 96.1%) at 0, 5, 50, 500, or 1000 ppm, equal to 0, 0.8, 7.8, 78, and 160 mg/kg bw per day for males and 0, 0.9, 9.4, 94, and 190 mg/kg bw per day for females, for 18 months. Each group included a satellite group of 10 mice of each sex that were killed at interim sacrifice after 52 weeks of treatment. In animals at 500 ppm, a slight reduction in the survival rate of males and increased pigment deposition in the spleens of males and females were observed at both interim and terminal sacrifices. At the highest dose, the survival rates of both males and females were reduced, and signs of mild haemolytic anaemia (a small but significant increase in the blood level of methaemoglobin and increased incidences of polychromasia and echinocytosis in erythrocytes) and further increases in splenic pigment deposition were observed at interim and/or terminal sacrifice. At terminal sacrifice, males had increased relative spleen weights, and females had an increased incidence of extramedullary haematopoiesis in the spleen. There was no evidence of an oncogenic effect at any dose. The NOAEL for general toxicity was 50 ppm, equal to 7.8 mg/kg bw per day (Trotter, 1992a). Rats Groups of 60 male and 60 female Crl:CD BR rats received diets containing technical-grade tebufenozide (purity, 96.1%) providing levels of 0, 10, 100, 1000, or 2000 ppm, equal to 0, 0.5, 4.8, 48, and 97 mg/kg bw per day for males and 0, 0.6, 6.1, 61, and 120 mg/kg bw per day for females, for two years. Each group included a satellite group of 10 rats of each sex that were killed at interim sacrifice during week 53; two sentinel groups of five rats of each sex per group were maintained to screen general health before and at the end of the treatment period. Animals at 1000 or 2000 ppm showed significant decreases in mean body weight and body-weight gain, the latter more pronounced in females, and females had a reduced mean food consumption throughout the study. Signs of mild haemolytic anaemia were seen only during the first 52 weeks of treatment, suggesting that the effects on the haematopoietic system were transient and reversible. Slight increases in the incidence and/or severity of pigment deposition (haemosiderin) were seen in the spleens of animals of each sex at interim and/or terminal sacrifices, suggesting active splenic erythrophagocytosis. In addition, females at 1000 and 2000 ppm had an increased frequency of swelling of body areas (principally the mammary gland regions) during the first 70 weeks of treatment; however, in the absence of any supporting histopathological findings in the mammary gland tissue or skin, the toxicological significance of these transient swellings could not be ascertained. No treatment-related neoplastic lesions were noted in any tissue or organ of any treated rat at any dose. The NOAEL for systemic toxicity was 100 ppm, equal to 4.8 mg/kg bw per day (Trutter, 1992b). (d) Reproductive toxicity Rats In a two-generation study, with one litter per generation, groups of 25 male and 25 female weanling Crl:CD BR rats were fed diets containing technical-grade tebufenozide (purity, 97.5%) providing dietary levels of 0, 10, 150, or 2000 ppm, equal to 0, 0.8, 12, and 150 mg/kg bw per day for males and 0, 0.9, 13, and 170 mg/kg bw per day for females. The diets were fed for 70 (F0) or 105 days (F1) before mating. No treatment-related effects were observed in either generation at the low dose. At 150 ppm, an increased severity of pigment deposition in the spleen of F0 and F1 females was reported. At the highest dose, the body weight and feed consumption of F0 and F1 males were decreased at some intervals before mating. Increased splenic pigment deposition and extramedullary haematopoiesis were seen in parental animals of each sex in both generations. The mean number of implantation sites in F1 females (not measured in F0) was decreased and the length of gestation in F1 (but not F0) dams increased. There was also a small increase in the number of pregnant females in both generations that had total resorptions and in the number of F1 females that died during delivery. The NOAEL was 10 ppm, equal to 0.8 mg/kg bw per day, for general toxicity and 150 ppm, equal to 12 mg/kg bw per day, for reproductive toxicity (Danberry et al., 1993). In a similar study, groups of 24 male and 24 female weanling Crj:CD(SD) rats were given diets containing technical-grade tebufenozide (purity, 97.2%) providing levels of 0, 25, 200, or 2000 ppm, equal to 0, 1.6, 13, and 130 mg/kg bw per day for males and 0, 1.8, 15, and 140 mg/kg bw per day for females, for 10 weeks before mating of the F0 and F1 parents to produce the respective F1 and F2 offspring. The study was terminated after weaning of the F2 litters. An increased incidence of splenic lesions, seen as blackish changes and/or congestion of the spleen, increased splenic extramedullary haematopoiesis, and haemosiderin-laden cells, occurred in F0 and F1 parental animals at 200 and 2000 ppm. At 2000 ppm, slight decreases in body-weight gain were seen in animals of each sex, and decreases in uterine and ovarian weights were reported; the changes were small and were considered not to be toxicologically significant. A significant reduction in mean body-weight gain was seen in F1 and F2 pups at 2000 ppm between lactation days 14 and 21. The study revealed no adverse effects on the reproductive ability of male or female rats. The NOAEL was 25 ppm, equal to 1.6 mg/kg bw per day, for systemic toxicity and 200 ppm, equal to 13 mg/kg bw per day, for reproductive toxicity (Aso, 1995). In both of the above studies, a consistent increase in the incidence of gross and histopathological findings in the spleen, including congestion, pigment, and extramedullary haematopoiesis, was seen in F0 and F1 parental animals. Although tebufenozide at the doses tested had no effect on the reproductive ability of male or female rats, the minor reproductive effects observed at 2000 ppm on parental females in the first study and on lactating pups in the second study could not be discounted. The overall NOAEL for reproductive toxicity was thus 200 ppm, equal to 13 mg/kg bw per day. (e) Developmental toxicity Rats In a range-finding study, groups of nine mated female Crl:CD BR rats were given technical-grade tebufenozide (purity, 96.8%) by gavage at doses of 0 (vehicle control), 25, 75, 200, or 400 mg/kg bw per day on days 6-15 of gestation. On day 20, all surviving dams were killed, and their fetuses were removed from the uterus and necropsied. No maternal, embryo, or fetal toxicity and no external gross malformations or anomalies in the fetuses were seen at any dose. The NOAEL for maternal, embryonic, and fetal toxicity and teratogenicity was thus 400 mg/kg bw per day, the highest dose tested. In a supplementary range-finding study, groups of six non-pregnant female Crl:CD BR rats were given technical-grade tebufenozide (purity, 96.8%) by gavage at doses of 0, 400, or 1000 mg/kg bw per day for 10 days. At 1000 mg/kg bw per day, a slight increase in liver weight was observed; however, in the absence of histopathological data, the toxicological significance of this finding could not be fully evaluated. On the basis of the very limited data provided, the NOAEL was 400 mg/kg bw per day (Solomon & Romanello, 1992). In the main study, groups of 25 mated Crl:CD BR VAF/Plus Sprague-Dawley rats were given technical-grade tebufenozide (purity, 96.1%) by gavage at doses of 0, 50, 250, or 1000 mg/kg bw per day on days 6-15 of presumed gestation (day 0 taken as the day spermatozoa were detected in a vaginal lavage or a copulatory plug was observed in situ). On gestation day 20, all surviving dams were killed, and their fetuses were removed and necropsied. At 1000 mg/kg bw per day, initial slight, transient reductions in mean body-weight gain and food consumption were seen during dosing, but the mean values over the study were not affected; the changes were considered not to be toxicologically significant. All of the fetuses showed normal development, and no signs of fetotoxicity and no treatment-related malformations were observed at any dose tested. The NOAEL was 1000 mg/kg bw per day for maternal toxicity and 1000 mg/kg bw per day, the highest dose tested, for embryo- and fetotoxicity and teratogenicity (Hoberman, 1991). Rabbits In a range-finding study, groups of six mated female Hra:(NZW)SPF rabbits were given technical-grade tebufenozide (purity, 96.4%) by gavage at doses of 0, 100, 300, or 1000 mg/kg bw per day on days 7-19 of presumed gestation (the day of mating confirmed by the presence of seminal fluid in the vulva). All surviving does were sacrificed, and all fetuses were removed and examined on day 29 of gestation. The single death due to an unknown cause among animals at 1000 mg/kg bw per day was unlikely to have been due to treatment, as no deaths occurred in the main study. No other signs of maternal toxicity or treatment-related disturbance of intrauterine development of the conceptuses were observed. All fetuses showed normal development, and no signs of fetal toxicity or treatment-related malformations were seen at any dose. The NOAEL for embryo- and fetotoxicity and teratogenicity was 1000 mg/kg bw per day, the highest dose tested (Lemen, 1991). In the main study, groups of 20 mated female New Zealand white rabbits were given technical-grade tebufenozide (purity, 97.5%) by gavage at doses of 0, 50, 250, or 1000 mg/kg bw per day on days 7-19 of presumed gestation (the day of mating confirmed by the presence of seminal fluid in the vulva). All surviving does were sacrificed, and their fetuses were removed and examined on day 29 of gestation. No treatment-related deaths, clinical signs of maternal toxicity, or disturbances of intrauterine development of the conceptuses were observed at any dose. All of the fetuses showed normal development, and no signs of fetotoxicity or treatment-related malformations were observed at any dose. The NOAEL for maternal toxicity, embryo- and fetotoxicity and teratogenicity was 1000 mg/kg bw per day, the highest dose tested (Swenson & Solomon, 1992). (f) Genotoxicity A battery of tests for mutagenicity was conducted to assess the potential of technical-grade tebufenozide (purity, > 95-97.5%) to induce gene mutation, chromosomal aberration, or unscheduled DNA synthesis. The results, summarized in Table 2, were all negative. (g) Special studies (i) Dermal and ocular irritation and dermal sensitization Technical-grade tebufenozide (purity, 96-97%) was not irritating to the skin and was minimally irritating to the eyes of male New Zealand white rabbits, according to Draize scale scoring (Krajewski et al., 1988a,b; Lutz & Parno, 1993). Table 2. Results of tests for the genotoxicity of technical-grade tebufenozide End-point Test system Concentration Purity Results Reference (%) In vitro Reverse mutation S. typhimurium 0, 50-5000a µg/plate > 95 Negativeb Black (1986) TA98, TA100, TA1535, TA1537 Reverse mutation S. typhimurium 0, 50-5000a µg/plate 96.1 Negativeb Sames & Streelman TA98, TA100, (1991) TA1535, TA1537 Reverse mutation S. typhimurium 0, 50-5000a µg/plate 96.1 Negativeb Sames & Elia (1993) TA98, TA100, 0, 160-1600a µg/plate Negativeb TA1535, TA1537 Reverse mutation S. typhimurium 0, 50-5000a µg/plate 96.1 Negativeb Sames & Elia (1994) TA98, TA100, 0, 30-300a µg/plate Negativeb TA1535, TA1537 Reverse mutation E. coli WP2 uvr A 0, 200-5000a µg/plate 96.1 Negativeb Watanabe (1992) Forward mutation Chinese hamster 0, 10-60 µg/ml 96.4 Negativeb Thilagar (1990a) ovary cells (hprt locus) Chromosomal aberration Chinese hamster 0, 5-30 µg/ml 96.8 Negativeb Thilagar (1987) ovary cells Unscheduled DNA Rat (SD) primary 0, 10-100a µg/ml 96.4 Negative Thilagar (1990b) synthesis hepatocytes 0, 10-60 µg/ml Negative In vivo Chromosomal aberration Rat (CD, 5-7 of each 0, 0.5-5.0 g/kg bw 97.5 Negative Gudi (1992) sex per dose) bone by single gavage marrow a Precipitation observed in all cultures b Conducted with and without exogenous metabolic activation Technical-grade tebufenozide (purity, 96%) did not sensitize the skin of guinea-pigs assessed in the maximization test (males) and the Buehler test (females) (Matsumoto, 1989; Glaza, 1993). (ii) Neurotoxicity Groups of 10 male and 10 female Crl:CD R BR rats were given single doses of technical-grade tebufenozide (purity, 96.1%) in 0.5% w/v aqueous methylcellulose by gavage at 0, 500, 1000, or 2000 mg/kg bw. All rats were subjected to functional observational battery testing and motor activity assessment before treatment and 1-3 h and 7 and 14 days after dosing, and a detailed neuropathological examination was carried out at the end of the 14-day observation period. No remarkable treatment-related neurological changes were found at any dose. Treatment-related responses were elicited in similar acute neurotoxicity studies conducted at the same testing laboratory with substances known to affect functional observational battery and motor activity testing, thus validating the competence of the laboratory in this type of testing. The NOAEL for the neurotoxic and neuropathological effects of tebufenozide was thus 2000 mg/kg bw, the highest dose tested (Swenson et al., 1994). (iii) Studies of metabolites Five metabolites of tebufenozide were tested for acute toxicity in Crj: CD-1 or Crl:CD-1 BR ICR mice. Metabolites RH-111788, RH-96595, RH-120970, RH-089886, and RH-112651 (see Figure 1) given orally induced no deaths and no clinical signs of systemic toxicity at doses up to 5000 mg/kg bw. The LD50 values for these metabolites in male and female mice was thus > 5000 mg/kg bw (Hazelton & Quinn, 1993). Four tebufenozide metabolites, RH-111788, RH-96595, RH-120970, and RH-089886, were tested for their potential to induce reverse mutation in Salmonella typhimurium strains TA98, TA100, TA1535, and TA1537 and in Escherichia coli strain WP2 uvr A at concentrations up to the limit of solubility (1250-2500 µg/plate), with and without exogenous metabolic activation. The results, summarized in Table 3, were negative (Hazelton & Quinn, 1993). Table 3. Results of tests for the genotoxicity of metabolites of tebufenozide Metabolite Concentration Result (µg/plate) RH-89886 (in rats, rice) 0, 313-5000a Negative RH-111788 (in rats, rice) 0, 313-5000a Negative RH-96595 (in rats, rice, soil) 0, 313-5000a Negative RH-120970 (in rats, rice) 0, 313-5000a Negative Potential for induction of reverse mutation in vitro in S. typhimurium TA98, TA100, TA1535, and TA1537 and in E. coli WP2 uvr A, with and without exogenous metabolic activation by a microsomal fraction from rat liver a Precipitation observed on all plates Comments Oral administration to rats of single doses of 3 or 250 mg/kg bw of 14C-labelled tebufenozide resulted in rapid absorption and excretion in urine and faeces, only trace amounts of 14C being recovered in expired air. The excretion profiles were similar, regardless of the position of the 14C label, the dose, the sex, or whether the rats had been pretreated with 30 ppm of unlabelled tebufenozide in the diet for two weeks. A mean total of 87-104% of the administered radiolabel was eliminated within 48 h, primarily via the faeces, which accounted for 90% of the 14C that was excreted; only minor amounts (1-8%) were excreted in urine and trace amounts (0.1-0.4%) in expired air. In animals at 3 mg/kg bw, absorption accounted for 35-39 % of the administered radiolabel; 30-34% was excreted in the bile and about 5% in the urine. In rats at 250 mg/kg bw, only about 4% of the administered dose was absorbed and metabolized. The highest levels of 14C in the blood were measured 0.5-12 h after dosing, and clearance of the radiolabel from the circulation was rapid. Tissue retention of 14C was low, suggesting that there is little or no bioaccumulation of tebufenozide in the body. Most of the 14C excreted in the faeces was in the form of unabsorbed (parent) tebufenozide, which accounted for about 60 and 90% of an administered dose of 3 and 250 mg/kg bw per day, respectively; no unchanged tebufenozide was detected in the urine. The absorbed 14C-tebufenozide was extensively metabolized in rats. There were no significant qualitative differences in the metabolic profiles associated with the position of the 14C label, the dose, sex, or whether rats were pretreated with unlabelled tebufenozide. In general, the 13-15 metabolites identified in the urine, faeces, and bile were identical. The main route of metabolism of tebufenozide appeared to be oxidation of benzylic carbons (A- or B-ring), resulting in a number of metabolites with various combinations of oxidation state at the three oxidized carbon centres and one metabolite produced by oxidation of a nonbenzylic, terminal carbon on the A-ring ethyl group. Tebufenozide was of low acute toxicity after administration to mice orally and to rats by the oral, dermal, or inhalation route. The oral LD50 in mice and rats was > 5000 mg/kg bw; the dermal LD50 in rats was > 5000 mg/kg bw; and the inhalation LC50 in rats was > 4.3 mg/litre. The metabolites were also of low acute toxicity to mice after oral administration. Tebufenozide was not irritating to the skin and was minimally irritating to the eyes of male rabbits; it was not a skin sensitizer in guinea-pigs. WHO has not classified tebufenozide for acute toxicity. Repeated short-term oral administration of tebufenozide to mice (2 and 13 weeks), rats (2, 4, and 13 weeks), and dogs (2, 6, 13, and 52 weeks) resulted primarily in haematotoxic effects (regenerative haemolytic anaemia and compensatory responses from the haematopoietic tissues). The NOAEL for these effects was 200 ppm, equal to 35 mg/kg bw per day, in mice in a 13-week study (0, 20, 200, 2000, and 20 000 ppm tested); 200 ppm, equal to 13.1 mg/kg bw per day, in rats in a 13-week study (0, 20, 200, 2000, and 20 000 ppm tested); 50 ppm, equal to 2 mg/kg bw per day, in dogs in a 13-week study (0, 50, 500, and 5000 ppm tested); and 50 ppm, equal to 1.8 mg/kg bw per day, in a one-year study in dogs (0, 15, 50, 250, and 1500 ppm tested). Repeated dermal applications of tebufenozide to rats for four weeks caused no systemic toxicity at doses < 1000 mg/kg bw per day. The dog appeared to be the most sensitive species for both short-term and long-term toxicity. In an 18-month study of toxicity and carcinogenicity in mice given tebufenozide in the diet at concentrations of 0, 5, 50, 500, or 1000 ppm, the NOAEL for systemic toxicity was 50 ppm, equal to 7.8 mg/kg bw per day, on the basis of a slightly reduced survival rate and mild regenerative haemolytic anaemia at higher doses. In a two-year study of toxicity and carcinogenicity in rats given tebufenozide in the diet at 0, 10, 100, 1000, or 2000 ppm, the NOAEL was 100 ppm, equal to 4.8 mg/kg bw per day, on the basis of decreased body weight and food consumption and mild regenerative haemolytic anaemia at higher doses. Tebufenozide was not carcinogenic to mice or rats under the conditions of the studies. Tebufenozide and its metabolites have been adequately tested for genotoxicity in a range of assays both in vitro and in vivo. The Meeting concluded that neither tebufenozide nor its metabolites are genotoxic. In two two-generation studies of reproductive toxicity in rats, with one litter per generation, doses of 0, 10, 150, or 2000 ppm and 0, 25, 200, or 2000 ppm were administered. The NOAEL for systemic (parental) toxicity was 25 ppm, equal to 1.6 mg/kg bw per day, on the basis of a consistent increase in the incidence of gross and histopathological lesions in the spleens (congestion, pigment, and extra-medullary haematopoiesis) of F0 and F1 parental animals at higher doses (200 and 2000 ppm). The NOAEL for reproductive toxicity was 13 mg/kg bw per day, on the basis of minor reproductive effects (decreased mean number of implantation sites, prolonged gestation, a slightly greater frequency of total resorptions, and a small increase in the number of dams that died during delivery) at the high dose of 2000 ppm in dams in the first study and in lactating pups (decreased mean weight gain on lactation days 14 and 21) in the second study. In studies of developmental toxicity in rats and rabbits, doses of 0, 50, 250, or 1000 mg/kg bw per day were administered. There was no evidence of teratogenic potential. The NOAEL for maternal, embryo-, and fetotoxicity and teratogenicity was 1000 mg/kg bw per day, the highest dose tested, in both species. In a study of acute neurotoxicity in rats, no treatment-related effects were seen when single doses of 0, 500, 1000, or 2000 mg/kg bw were administered. The NOAEL for acute neurotoxicity and neuro- pathological effects was 2000 mg/kg bw, the highest dose tested. In summary, exposure to tebufenozide by the oral route results primarily in haematotoxicity. The main target of its action is the peripheral haematopoietic system; the pivotal toxicological end-point of concern, which is seen consistently across all species tested, is mild regenerative haemolytic anaemia with compensatory responses from the haematopoietic tissues. An ADI of 0-0.02 mg/kg bw was established for tebufenozide on the basis of the NOAELs for haematotoxicity of 1.8 mg/kg bw per day in the one-year study in dogs and 1.6 mg/kg bw per day in a two-generation study of reproductive toxicity in rats, using a safety factor of 100. Toxicological evaluation Levels that cause no toxic effect Mouse: 200 ppm, equal to 35 mg/kg bw per day (13-week study of toxicity) 50 ppm, equal to 7.8 mg/kg bw per day (haematotoxicity in an 18-month study of toxicity and carcinogenicity) Rat: 200 ppm, equal to 13 mg/kg bw per day (13-week study of toxicity) 100 ppm, equal to 4.8 mg/kg bw per day (haematotoxicity in a two-year study of toxicity and carcinogenicity) 25 ppm, equal to 1.6 mg/kg bw per day (maternal haematotoxicity in a two-generation study of reproductive toxicity) 200 ppm, equal to 13 mg/kg bw per day (reproductive toxicity in a two-generation study) 1000 mg/kg bw per day, the highest dose tested (maternal, embryo-, and fetotoxicity and teratogenicity in a study of developmental toxicity) Rabbit: 1000 mg/kg bw per day, the highest dose tested (maternal, embryo-, and fetotoxicity and teratogenicity in a study of developmental toxicity) Dog: 50 ppm, equal to 1.8 mg/kg bw per day (haemotoxicity in a one-year study of toxicity) Estimate of acceptable daily intake for humans 0-0.02 mg/kg bw Studies that would provide information useful for continued evaluation of the compound 1. Observations in humans 2. Studies on the mechanism of haematotoxicity Toxicological criteria for estimating guidance values for dietary and non-dietary exposure to tebufenozide Exposure Relevant route, study type, species Results, remarks Short-term (1-7 days) Oral, toxicity, rat LD50 > 5000 mg/kg bw Dermal, toxicity, rat LD50 > 5000 mg/kg bw Inhalation, 4 h, toxicity, rat LC50 > 4.3 mg/litre Dermal, irritation, rabbit Not irritating Ocular, irritation, rabbit Minimally irritating Dermal, sensitization, guinea-pig Not sensitizing Medium-term (1-26 weeks) Repeated dietary, 90 days, toxicity, dog NOAEL = 2 mg/kg bw per day, primarily haematotoxicity Repeated dermal, 28 days, toxicity, rat NOAEL = 1000 mg/kg bw per day, highest dose tested Repeated dietary, reproductive toxicity, rat NOAEL = 13 mg/kg bw per day, minor reproductive effects Repeated gavage, developmental toxicity, NOAEL = 1000 mg/kg bw per day, highest dose rat and rabbit tested; maternal, embryo-, and fetal toxicity and teratogenicity Long-term (> 1 year) Repeated dietary, 1 year, toxicity, dog NOAEL = 1.8 mg/kg bw per day, primarily haematotoxicity References Aso, S. (1995) Two-generation reproduction study of RH-5992 in rats. Unpublished report No. 93RC-101 from Hita Research Laboratories, Oita, Japan. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Black, C.A. (1986) RH-75,992: Microbial mutagenicity assay (Ames test). Unpublished report No. 86R-0013 from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Clay, H. (1992). RH-5992: 90-day oral (dietary) administration toxicity study in the beagle. Unpublished report No. 90RC-062 from Hazleton UK, North Yorkshire, United Kingdom. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Danberry, T.L., Romanello, A.S., Donofrio, K.F. & O'Hara, G.P. (1993) RH-5992: Two-generation reproduction study in rats. Unpublished report No. 9OR-202A from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Glaza, S.M. (1993) Dermal sensitization study of RH-5992 technical in guinea pigs - maximization test. Unpublished report No. 92RC-101 from Hazleton Wisconsin, Inc., WI, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Gudi, R (1992) RH-5992 technical: Acute test for chemical induction of chromosome aberration in rat bone marrow cells in vivo. Unpublished report No. 9ORC-203 from Sitek Research Laboratories, MD, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Hawkins, D.R. & Hazelton, G.A. (1993) 14C-RH-5992: Biliary excretion study in rats, supplemental report A: Metabolism of RH-5992 in rats. Unpublished report No. 9ORC-058A from Rohm & Haas Co., Agricultural Products Development Department, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Hawkins, D.R., Spencer, W.O. & Hazelton, G.A. (1992) 14C-RH-5992 pharmacokinetic study in rats, supplemental report A: Metabolism of RH-5992 in rats. Unpublished report No. 91RC-004A from Rohm & Haas Co., Agricultural Products Development Department, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Hawkins, D.R., Spencer W.O. & Hazelton, G.A. (1993) 14C-RH-5992: Pharmacokinetic study in rats, supplemental report B: Metabolism of RH-5992 in rats. Unpublished report No. 91RC-004B from Rohm & Haas Co., Agricultural Products Development Department, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Hazelton, G.A. & Quinn, D.L. (1993) Hazard evaluation of RH-5992 technical in human and domestic animals. Part I: Hazard identification and evaluation. Unpublished report No. 93R-1039 from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Hazelton, G.A. & Quinn, D.L. (1995) Evaluation of rat reproduction studies conducted with RH-5992. Unpublished report No. 95R-1068 from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Hoberman, A.M. (1991) RH-5992: Oral developmental toxicity (embryo- fetal toxicity and teratogenic potential) study in rats. Unpublished report No. 9ORC-059 from Argus Research Laboratories, Inc., PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Kehoe, D.F. (1990) RH-5992: Two-week dietary range-finding study in male dogs. Unpublished report No. 87RC-034 from Hazleton Laboratories America, Inc., WI, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Krajewski, R.J., Morrison, R.D. & Baldwin, R.C. (1988a) RH-75,992: Skin irritation study in rabbits. Unpublished report No. 87R-088 from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Krajewski, R.J., Morrison, R.D. & Baldwin, R.C. (1988b) RH-75,992: Eye irritation study in rabbits. Unpublished report No. 87R-084 from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Kyle, M.E. (1992) RH-5992: Two-week dietary range-finding study in male mice. Unpublished report No. 86R-228A from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Kyle, M.E. & Quinn, D.L. (1992) RH-5992: Two-week dietary range- finding study in rats. Unpublished report No. 86R-226A from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Lemen, J.K. (1991) RH-5992: Range-finding rabbit developmental toxicity study. Unpublished report No. 89RC-100 from Hazleton Laboratories America, Inc., VA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. LeVan, L.W. (1991) 14C-RH-5992: Distribution of radioactivity in rats following a single oral dose. Unpublished report No. 89RC-099 from Hazleton Laboratories America, Inc., WI, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Lutz, M.F. & Parno, J.R. (1993) RH-75,992: Eye irritation study in rabbits. Unpublished report No. 93R-237 from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Matsumoto, R. (1989) Skin sensitization study of RH-5992 (technical) in the guinea pig. Unpublished report No. 9ORC-1002A from Bozo Research Centre, Inc., Tokyo, Japan. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Morrison, R.D. & Hamilton, J.D. (1991a) RH-75,992 technical: Acute oral toxicity study in male and female mice. Unpublished report No. 91R-003 from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Morrison, R.D. & Hamilton, J.D. (1991b) RH-75,992 technical: Acute oral toxicity study in male and female rats. Unpublished report No. 9OR-199 from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Morrison, R.D. & Hamilton, J.D. (1991c) RH-75,992 technical: Acute dermal toxicity study in male and female rats. Unpublished report No. 9OR-200 from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Morrison, R.D., Carbone, J.P., Parno, J.R. & Gillette, D.M. (1993) RH-75,992 technical and RH-75,992 2F formulation: Four-week dermal toxicity study in rats. Unpublished report No. 92R-150 from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Osheroff, M.R. (1991a) RH-5992: 13-Week dietary toxicity study in mice. Unpublished report No. 89RC-102 from Hazleton Laboratories America, Inc., VA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Osheroff, M.R. (1991b) RH-5992: Four-week range-finding dietary toxicity study in rats. Unpublished report No. 89RC-101A from Hazleton Laboratories America, Inc., MD, USA. Submitted to WHO by Rohm & Haas Co., PA, USA. Osheroff, M.R. (1991c) RH-5992: 13-week dietary toxicity study in rats. Unpublished report No. 89RC-101 from Hazleton Laboratories America, Inc., VA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Richards, J.F. (1992) RH-5992: 52-week oral (dietary administration) chronic toxicity study in the beagle. Unpublished report No. 90RC-206 from Hazleton UK, North Yorkshire, United Kingdom. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Sames, J.L. & Elia, M.C. (1993) RH-75,992 technical: Salmonella typhimurium gene mutation assay (Ames test). Unpublished report No. 93R-094 from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Sames, J.L. & Elia, M.C. (1994) RH-75,992 technical: Salmonella typhimurium gene mutation assay (Ames test). Unpublished report No. 93R-236 from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Sames, J.L. & Streelman, D.R. (1991) RH-75,992 technical: Salmonella typhimurium gene mutation assay (Ames test). Unpublished report No. 9IR-167 from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Solomon, H.M. & Romanello, A.S. (1992) RH-5992: Range-finding (gavage) developmental toxicology study in rats. Unpublished report No. 87R-105A from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Struble, C.B. & Hazelton, G.A. (1992a) 14C-RH-5992: Biliary excretion study in rats. Unpublished report No. 90RC-058 from Hazleton Wisconsin, Inc., WI, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Struble, C.B. & Hazelton, G.A. (1992b) 14C-RH-5992: Pharmacokinetic study in rats. Unpublished report No. 91RC-004 from Hazleton Wisconsin, Inc., WI, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Swenson, R.E. & Solomon, H.M. (1992) RH-5992: Oral (gavage) developmental toxicity study in rabbits. Unpublished report No. 90R-201 from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Swenson, R.E., Gillette, D.M. & Parno, J.R. (1994) RH-75,992: Acute oral (gavage) neurotoxicity study in rats. Unpublished report No. 93R-093 from Rohm & Haas Co., Toxicology Department, Philadelphia, PA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Thilagar, A. (1987) RH-75,992: Test for chemical induction of chromosome aberration using monolayer cultures of Chinese hamster ovary (CHO) cells with and without metabolic activation. Unpublished report No. 88RC-011 from Sitek Research Laboratories, MD, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Thilagar, A. (1990a) RH-5992: Test for chemical induction of gene mutation at the HGPRT locus in cultured Chinese hamster ovary (CHO) cells with and without metabolic activation. Unpublished report No. 89RC-097 from Sitek Research Laboratories, MD, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Thilagar, A. (1990b) RH-5992: Test for chemical induction of unscheduled DNA synthesis in rat primary hepatocyte cultures by autoradiography. Unpublished report No. 89RC-098 from Sitek Research Laboratories, MD, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Trutter, J.A. (1992a) RH-5992: 18-Month dietary oncogenicity study in mice. Unpublished report No. 90RC-061 and 90RC-061A from Hazleton Washington, Inc., VA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Trutter, J.A. (1992b) RH-5992: 24-Month combined dietary chronic toxicity and oncogenicity study in rats. Unpublished report No. 90RC-060 and 90RC-060A from Hazleton Washington, Inc., VA, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Ulrich, C.E. (1992) RH-5992 (technical): Acute inhalation toxicity evaluation in rats. Unpublished report No. 90RC-057 from International Research and Development Corporation, MI, USA. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Watanabe, K. (1992) RH-5992: Reverse mutation assay with E. coli (WP2 uvr strain). Unpublished report No. 92RN-1010 from The Institute of Environmental Toxicology, Tokyo, Japan. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA. Yoshida, A. (1992) RH-5992: Blood recovery study in dogs. Unpublished report No. 92RC-1040 from The Institute of Environmental Toxicology, Tokyo, Japan. Submitted to WHO by Rohm & Haas Co., Philadelphia, PA, USA.
See Also: Toxicological Abbreviations Tebufenozide (JMPR Evaluations 2003 Part II Toxicological)