Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tetrafluoroethylene is used in the production of polytetrafluoroethylene (Teflon(R)) and other polymers. Tetrafluoroethylene was nominated by the National Cancer Institute for toxicity and carcinogenicity studies based on the potential for human exposure to the chemical due to the large production volume and on the lack of adequate data for tetrafluoroethylene in the literature. Male and female F344/N rats and B6C3F1 mice were exposed to tetrafluoroethylene (98% to 99% pure) by whole body inhalation exposure for 16 days, 13 weeks, or 2 years. Genetic toxicity studies were conducted in mouse peripheral blood erythrocytes. 16-DAY STUDY IN RATS: Groups of five male and five female F344/N rats were exposed to 0, 312, 625, 1,250, 2,500, or 5,000 ppm tetrafluoroethylene by inhalation for 6 hours per day, 5 days per week for a total of 12 exposures during a 16-day period. All rats survived to the end of the study. The final mean body weights and body weight gains of males and females exposed to 5,000 ppm were significantly less than those of the controls. The mean body weight gain of females exposed to 2,500 ppm was also significantly less than that of the controls. There were no exposure-related clinical findings in male or female rats. There were no significant differences in hematology parameters that were considered to be related to tetrafluoroethylene exposure. Absolute and relative kidney weights of all exposed groups of males were significantly greater than those of the controls, as were those of females in the 2,500 and 5,000 ppm groups. The absolute kidney weight of females exposed to 1,250 ppm was also significantly greater than that of the controls. The relative liver weights of all exposed groups of males and the absolute liver weights of males in the 625 and 2,500 ppm groups were significantly greater than those of the controls. Increased incidences of renal tubule degeneration occurred in males and females exposed to 625 ppm or greater; this lesion was located predominantly at the corticomedullary junction. The severity of degeneration increased with increasing exposure concentration and was slightly greater in males than females. 16-DAY STUDY IN MICE: Groups of five male and five female B6C3F1 mice were exposed to 0, 312, 625, 1,250, 2,500, or 5,000 ppm tetrafluoroethylene by inhalation for 6 hours per day, 5 days per week for a total of 12 exposures during a 16-day period. All mice survived to the end of the study. Final mean body weights and body weight gains of all exposed groups of mice were similar to those of the controls. There were no exposure-related clinical findings in male or female mice. There were no significant differences in hematology parameters that were considered to be related to tetrafluoroethylene exposure. The absolute and relative liver weights of females exposed to 5,000 ppm were significantly greater than those of the controls, as was the absolute kidney weight of females in that group and the absolute liver weight of females in the 2,500 ppm group. Renal tubule karyomegaly was observed in male and female mice in the 1,250, 2,500, and 5,000 ppm groups, and the severity of this lesion increased with increasing exposure concentration. Karyomegaly was located predominantly in the inner renal cortex. 13-WEEK STUDY IN RATS: Groups of 10 male and 9 or 10 female F344/N rats were exposed to 0, 312, 625, 1,250, 2,500, or 5,000 ppm tetrafluoroethylene by inhalation for 6 hours per day, 5 days per week, for 13 weeks. All rats survived to the end of the study. The final mean body weight and body weight gain of males exposed to 5,000 ppm were significantly less than those of the controls, as was the mean body weight gain of females in this exposure group. There were no clinical findings attributed to exposure to tetrafluoroethylene. Exposure of rats to tetrafluoroethylene resulted in a concentration-dependent normocytic, normochromic, nonresponsive anemia consistent with a secondary hypoproliferative anemia. An exposure concentration-dependent proteinuria also occurred, consistent with renal tubule th renal tubule degeneration observed histopathologically. The absolute and relative liver weights of all exposed groups of males and of females in the 5,000 ppm group were significantly greater than those of the controls. The absolute and relative right kidney weights of males and females exposed to 1,250 ppm or greater and of females in the 625 ppm group were also significantly greater than those of the controls. There were no differences in sperm morphology or vaginal cytology parameters between control and exposed groups of rats. Incidences of renal tubule degeneration in males exposed to 625 ppm or greater and in females exposed to 2,500 or 5,000 ppm were significantly greater than those in the controls. Renal lesions were similar to those observed in the 16-day study and were located predominantly at the corticomedullary junction. 13-WEEK STUDY IN MICE: Groups of 10 male and 10 female B6C3F1 mice were exposed to 0, 312, 625, 1,250, 2,500, or 5,000 ppm tetrafluoroethylene by inhalation for 6 hours per day, 5 days per week, for 13 weeks. All mice survived to the end of the study. Final mean body weights and body weight gains of all exposed groups of male and female mice were generally similar to those of the controls. There were no clinical findings that were considered to be related to tetrafluoroethylene exposure. Exposure of mice to tetrafluoroethylene resulted in a concentration-dependent normocytic, normochromic, nonresponsive anemia, consistent with a secondary hypoproliferative anemia, and in polyuria. Differences in sperm morphology parameters and estrous cycle lengths were not considered to be exposure related. Incidences of karyomegaly of the renal tubule epithelial cells in male and female mice exposed to 1,250 ppm or greater were significantly greater than those in the controls. Karyomegaly was similar to that observed in the 16-day study and was observed primarily in the inner renal cortex. 2-YEAR STUDY IN RATS: Groups of 60 male rats were exposed to 156, 312, or 625 ppm and groups of 60 female rats were exposed to 312, 625, or 1,250 ppm tetrafluoroethylene by inhalation for 6 hours per day, 5 days per week, for 104 weeks, with an observation period of 11 days following the final exposure. Ten male and ten female rats from each exposure group were evaluated at 15 months for organ weights and clinical pathology. Survival, Body Weights, and Clinical Findings: Survival rates of males in the 625 ppm group and of all exposed groups of females were significantly less than those of the controls. Mean body weights of males exposed to 625 ppm were lower than those of the controls from week 81 until the end of the study, and the mean body weight of 1,250 ppm females was slightly lower than that of the controls at the end of the study. The only clinical finding associated with exposure to tetrafluoroethylene was opacity of the eyes in exposed groups of female rats; this change was observed microscopically as cataracts. Hematology, Clinical Chemistry, and Urinalysis: At the 15-month interim evaluation, there were no differences in hematology, clinical chemistry, or urinalysis parameters that were considered to be related to tetrafluoroethylene exposure. Pathology Findings: The absolute and relative kidney weights of males exposed to 625 ppm and females exposed to 1,250 ppm and the absolute kidney weight of females exposed to 625 ppm were significantly greater than those of the controls at the 15-month interim evaluation. At 15 months, renal tubule hyperplasia was observed in one male exposed to 312 ppm and one male and one female exposed to 625 ppm; oncocytic hyperplasia was observed in one female exposed to 1,250 ppm. At the end of the study, incidences of renal tubule adenoma were greater in males and females exposed to 312 ppm or greater than those in the controls. This exposure-related increase was confirmed by examination of step sections (extended evaluations). At the end of the study, the incidences of renal tubule hyperplasia in males exposed to 625 ppm and females exposed to 1,250 ppm were significantly greater than those in the controls. The incidences of renal tubule adenoma and renal tubule adenoma or carcinoma (combined) in the extended evaluations and in the standard and extended evaluations (combined) in the 1,250 ppm female group and the 625 ppm male group were significantly greater than those in the controls, and the incidences occurred with significant positive trends. Oncocytic hyperplasia was observed at the end of the study in one male exposed to 312 ppm and in three females exposed to 1,250 ppm. At 15 months and at the end of the study, the incidences of renal tubule degeneration in all exposed groups of males and in females in the 625 and 1,250 ppm groups were greater than those in the controls. Renal tubule degeneration was similar to that observed in the 13-week study and was located predominantly at the corticomedullary junction. The severity of nephropathy generally increased with increasing exposure concentration in male rats at 15 months and 2 years. The absolute and relative liver weights of females in the 1,250 ppm group and the absolute liver weight of females exposed to 625 ppm were significantly greater than those of the controls at the 15-month interim evaluation. At 2 years, the incidences of hepatocellular carcinoma and hepatocellular adenoma or carcinoma (combined) in males exposed to 312 ppm, the incidences of hepatocellular adenoma and adenoma or carcinoma (combined) in females in all exposed groups, and the incidences of hepatocellular carcinoma in females exposed to 312 or 625 ppm were significantly greater than those in the controls. Also at 2 years, the incidence of hemangiosarcoma in females exposed to 625 ppm was significantly greater than that in the controls. In all exposed groups of males, the incidences of clear cell foci at 15 months were greater than those in the controls; at 2 years, the incidences of eosinophilic foci in all exposed groups of males and the incidences of basophilic and mixed cell foci in males in the 312 and 625 ppm groups were greater than those in the controls. The incidences of mixed cell foci at 15 months in females exposed to 625 or 1,250 ppm and at 2 years in females exposed to 1,250 ppm were also significantly greater than those in the controls. At the end of the 2-year study, increased incidences of cystic degeneration occurred in the liver of all exposed groups of males, and increased incidences of hepatic angiectasis were observed in exposed groups of females. Incidences of mononuclear cell leukemia in males exposed to 156 ppm and in all exposed groups of females were significantly greater than those in the controls. Incidences of cataracts in females exposed to 1,250 ppm were greater than those in the controls at the end of the 2-year study. At the end of the study, there were slight increases in the incidences of testicular interstitial cell adenoma in rats exposed to 312 or 625 ppm. 2-YEAR STUDY IN MICE: Groups of 58 male and 58 female B6C3F1 mice were exposed to 0, 312, 625, or 1,250 ppm tetrafluoroethylene by inhalation for 6 hours per day, 5 days per week, for 95 to 96 weeks. Ten male and ten female mice from each exposure group were evaluated at 15 months for organ weights. Survival, Body Weights, and Clinical Findings: The survival rates of all exposed groups of males and females were significantly less than those of the controls. Because of the reduced survival due to exposure-related liver neoplasms, the study was terminated during week 96. Mean body weights of exposed groups of males and females were generally similar to those of the controls, except at the end of the study, when they were somewhat less than those of the controls. There were no clinical findings related to tetrafluoroethylene exposure. Pathology Findings: At the 15-month interim evaluation, there were no differences in absolute or relative kidney, liver, or lung weights between exposed and control groups of mice. At the end of the study, the incidences of multifocal coagulative necrosis of the liver were increased in males in the 625 and 1,250 ppm groups. Also at the end of the study, females in all exposed groups had greater incidences of hematopoietic cell proliferation in the liver than the controls. Angiectasis occurred in all exposed groups of males and females at 15 months and at the end of the study. At the 15-month interim evaluation, hemangiosarcomas were observed in three males exposed to 1,250 ppm and in one female exposed to 312 ppm. The incidences of hemangiosarcoma in all exposed groups of males and females at the end of the study were significantly greater than those in the controls and exceeded the historical chamber control ranges. Also at the end of the study, the incidences of hemangioma in males and females exposed to 312 ppm and in males exposed to 625 ppm were also significantly greater than those in the controls and exceeded the range in historical chamber controls. At 15 months, hepatocellular adenomas and carcinomas occurred in control males and all exposed groups of males and females. Females exposed to 625 or 1,250 ppm had significantly greater incidences of eosinophilic foci than the controls at the 15-month interim evaluation. At the end of the study, the incidences of eosinophilic foci in males exposed to 625 or 1,250 ppm and in females exposed to 312 or 625 ppm were significantly greater than those in the controls. In male and female mice, increased incidences of a variety of hepatocellular neoplasms, including adenomas, multiple adenomas, carcinomas, and multiple carcinomas, were considered related to tetrafluoroethylene exposure. At the end of the study, the incidences of histiocytic sarcoma (all organs) in all exposed groups of males and females were significantly greater than those in the controls and exceeded the historical control ranges for all organs. The greatest incidences of histiocytic sarcomas were observed in the liver and lung, but these neoplasms were also observed in the spleen, lymph nodes, bone marrow, and kidney. Significantly increased incidences of renal tubule dilatation (males) and karyomegaly (males and females), located predominantly in the inner cortex, were observed in mice exposed to 625 or 1,250 ppm at 15 months. At the end of the study, the increased incidences of dilatation and karyomegaly in all exposed groups of males and of karyomegaly in 1,250 ppm females were generally significant. Incidences of hematopoietic cell proliferation in the spleen of all exposed groups of males and females were significantly greater than those in the controls at the end of the study. Additionally, the severity of this lesion increased with increasing exposure concentration. GENETIC TOXICOLOGY: No increases in the frequency of micronucleated erythrocytes were observed in peripheral blood samples obtained from male and female mice at the end of the 13-week inhalation study of tetrafluoroethylene. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was clear evidence of carcinogenic activity of tetrafluoroethylene in male F344/N rats based on increased incidences of renal tubule neoplasms (mainly adenomas) and hepatocellular neoplasms. There was clear evidence of carcinogenic activity of tetrafluoroethylene in female F344/N rats based on increased incidences of renal tubule neoplasms, liver hemangiosarcomas, hepatocellular neoplasms, and mononuclear cell leukemia. There was clear evidence of carcinogenic activity of tetrafluoroethylene in male and female B6C3F1 mice based on increased incidences of liver hemangiomas and hemangiosarcomas, hepatocellular neoplasms, and histiocytic sarcomas. Slight increases in the incidences of mononuclear cell leukemia and testicular interstitial cell adenomas in male rats may have been related to exposure to tetrafluoroethylene. Exposure of rats to tetrafluoroethylene resulted in increased incidences of renal tubule hyperplasia and degeneration in males and females, increased severity of kidney nephropathy in males, and increased incidences of liver angiectasis and cataracts in females. Exposure of mice to tetrafluoroethylene resulted in increased incidences of hematopoietic cell proliferation of the liver in females, liver angiectasis in males and females, renal tubule dilatation in males, renal tubule karyomegaly in males and females, and splenic hematopoietic cell proliferation in males and females. Synonyms: Perfluoroethylene; tetrafluoroethene; 1,1,2,2-tetrafluoroethylene; TFE
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PMID:NTP Toxicology and Carcinogenesis Studies of Tetrafluoroethylene (CAS No. 116-14-3) in F344 Rats and B6C3F1 Mice (Inhalation Studies). 1259 25

C.I. Pigment Red 3, a yellowish red solid, is widely used for coloring paints, inks, plastics, and rubber, and in textile printing. It is used in a wide range of consumer items such as wallpaper, typewriter ribbons, carbon paper, and art materials. Toxicology and carcinogenicity studies were conducted by feeding groups of F344/N rats and B6C3F1 mice of each sex diets containing C.I. Pigment Red 3 (97% pure) for 2 weeks, 13 weeks, and 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium and cultured Chinese hamster ovary cells. 2-Week Studies: Groups of five rats and five mice of each sex were given feed containing 0, 6,000, 12,500, 25,000, 50,000, or 100,000 ppm C.I. Pigment Red 3 for 2 weeks. No chemical-related deaths occurred in rats or mice. Final mean body weights of exposed rats and male mice were lower than controls; female mice that received 6,000 and 50,000 ppm had significantly increased final mean body weights compared to that of the controls. The feed consumption of treated rats and mice was slightly greater than that of the controls, suggesting that C.I. Pigment Red 3 had no adverse effects on the feed palatability. Dose-related decreases in erythrocyte counts and hematocrit values and an increase in reticulocyte counts were observed in rats. Changes in these parameters were observed in mice, but there were no clear, dose-related trends. 13-Week Studies: Groups of ten rats and ten mice of each sex were given feed containing 0, 3,000, 6,000, 12,500, 25,000, or 50,000 ppm C.I. Pigment Red 3 for 13 weeks. No chemical-related deaths were observed in rats or mice. The final mean body weights of exposed female rats were significantly lower than that of the controls; the final mean body weights of exposed male rats and exposed mice were similar to controls. There were significant increases in relative liver and kidney weights of exposed male rats. Increases in the relative liver weights in mice did not occur with a dose-related trend and thus they were not considered related to chemical administration. Sites for the toxicity of C.I. Pigment Red 3 were the bone marrow, kidney, liver, and spleen in rats. Lesions observed in rats included bone marrow hyperplasia, congestion and hematopoietic cell proliferation of the spleen, and iron-positive pigmentation of the spleen, kidney, and liver. Sites for the toxicity of C.I. Pigment Red 3 in mice were the liver, kidney, and spleen in males and the liver and spleen in females. Lesions noted among mice in the spleen were hematopoietic cell proliferation and iron-positive pigmentation. In the liver, there was hematopoietic cell proliferation in male and female mice. Cytomegaly occurred in the renal tubule epithelium of the male mouse kidney. 2-Year Studies: Doses selected for the 2-year feed studies were 0, 6,000, 12,500, and 25,000 ppm for rats and 0, 12,500, 25,000, and 50,000 ppm for mice. The dose selection for rats was based on body weight changes observed for females that received 50,000 ppm; the dose selection for mice was based on the lack of body weight depression or death at the doses tested during the 13-week studies. Concentrations higher than 50,000 ppm in the feed were not used because higher levels might have adversely affected the nutritional value of the diet during the 2-year studies. Body Weight, Feed Consumption, Clinical Findings, and Survival in the 2-Year Studies: Final mean body weights for male rats that received 25,000 ppm, female rats that received 12,500 and 25,000 ppm, and male and female mice that received 50,000 ppm were more than 10% lower than those of the controls. Feed consumption of exposed rats and mice was similar to that of the controls. No clinical findings indicative of toxicity were observed in rats or mice. The survival of low-dose male rats was greater than that of the controls (0 ppm, 28/50; 6,000 ppm, 40/50; 12,500 ppm, 28/50; 25,000 ppm, 20/50). Survival of exposed female rats and exposed male mice was similar to the controls; the survival of high-dose female mice was significantly decreased compared to thcompared to that of the controls (39/50, 37/50, 31/50, 25/50). The reduced survival in this dose group may have been due to the increased incidence of ovarian abscesses. Neoplasms and Nonneoplastic Lesions in the 2-Year Studies: Benign adrenal pheochromocytomas were significantly increased in the 12,500 and 25,000 ppm groups of male rats compared to the controls (22/50, 29/50, 35/50, 34/50). However, malignant neoplasms were not increased in incidence (6/50, 7/50, 10/50, 4/50). The incidence of adrenal pheochromocytomas in dosed groups exceeded the range for NTP historical controls for feed studies (22%-48%), and the increased incidence of this neoplasm was attributed to C.I. Pigment Red 3 administration. Squamous cell papillomas of the skin occurred with a positive trend in male rats (0/50, 4/50, 2/50, 6/50), and the incidence in the high-dose group was significantly greater than that of the controls. A poorly differentiated squamous cell carcinoma (diagnosed as carcinoma) was observed in a control male. The historical control rate for squamous cell papillomas in NTP feed studies is low (16/800 or 2%, range 0%-4%), and the higher incidence of this tumor in male rats may have been caused by the administration of C.I. Pigment Red 3. Hepatocellular adenomas occurred with a positive trend in female rats, with a significantly greater incidence in the high-dose group than in the control group (0/50, 0/50, 1/50, 10/50). This neoplasm has occurred in only one historical control group in NTP feed studies (3/800, range 0%-6%), and the increase in hepatocellular adenomas in female rats was attributed to chemical administration. Chemical-related nonneoplastic lesions observed in the livers of male and female rats included eosinophilic or mixed type foci of cellular alteration. Foci were often accompanied by angiectasis and cystic degeneration in males and by granulomas and cholesterol pigmentation in females. Chronic nephropathy occurred with increased severity in exposed male and female rats. The lesions were more severe in males than in females. Other lesions considered secondary to renal disease included parathyroid gland hyperplasia, fibrous osteodystrophy of the bone, and mineralization of various organs (stomach, intestine, heart, and blood vessels). The increased incidence of hyperplasia of the transitional epithelium of the renal papilla observed in treated rats was considered to be part of the chronic nephropathy. Zymbal's gland carcinoma incidences were marginally increased in the mid- and high-dose male rats (0/50, 0/50, 2/50, 3/50). The incidence in the high-dose group was outside the NTP historical control range (0%-4%), and the Zymbal's gland carcinomas may have been related to C.I. Pigment Red 3 administration. Mononuclear cell leukemias, mammary gland fibroadenomas, and preputial gland/clitoral gland adenomas occurred at lower incidences in exposed male and female rats. The decrease in mononuclear cell leukemia was attributed to the direct effect of C.I. Pigment Red 3 or its metabolites on the mechanism responsible for inducing leukemias in aging rats, while the decreased incidence of mammary gland fibroadenomas might be attributed to decreased body weights in female rats. The cause of the decreased incidences of preputial and clitoral gland tumors is unknown. Tubule adenomas of the renal cortex occurred at a significantly higher incidence in high-dose male mice than in controls (0 ppm, 0/50; 12,500 ppm, 0/50; 25,000 ppm, 0/50; 50,000 ppm, 6/50). Because this tumor occurred only in exposed males and was outside the range for NTP historical controls in feed studies (0%-2%), renal cortical tubule adenomas in male mice were considered to be related to the administration of C.I. Pigment Red 3. Follicular cell adenoma of the thyroid gland occurred with a positive trend in male mice (0/50, 0/49, 1/50, 5/50). Theincidence in the high-dose group was significantly greater than that in the controls. This chemical-related effect is supported by the increased incidence of follicular cell hyperplasia. Because the incidence of this tumor exceeded the range of the historical controls from NTP feed studies (0%-4%), the increase of follicular cell adenoma was attributed to chemical administration. Female mice receiving C.I. Pigment Red 3 had a significant increase in follicular cell hyperplasia but showed no increase in tumor incidence at this site. Focal renal tubule hyperplasia and cystic hyperplasia occurred in exposed male mice but not in the controls. Cytomegaly (karyomegaly) of the renal tubule epithelium was seen in all treated male mice. The severity of the accompanying chronic nephropathy was increased in both male and female mice. Genetic Toxicology: C.I. Pigment Red 3 was mutagenic in Salmonella typhimurium strains TA100 and TA98 in the presence of exogenous metabolic activation (S9); no increases in gene mutation were observed in strains TA1535 and TA1537, with or without S9. C.I. Pigment Red 3 did not induce sister chromatid exchanges or chromosomal aberrations in Chinese hamster ovary cells in either the presence or the absence of S9. Conclusions: Under the conditions of these 2-year feed studies, there was some evidence of carcinogenic activity of C.I. Pigment Red 3 in male F344/N rats as exhibited by increased incidences of benign pheochromocytomas of the adrenal gland. The marginal increase in the incidences of squamous cell papillomas of the skin and Zymbal's gland carcinomas may have been related to C.I. Pigment Red 3 administration. There was some evidence of carcinogenic activity of C.I. Pigment Red 3 in female F344/N rats as indicated by the increased incidence of hepatocellular adenomas. There was some evidence of carcinogenic activity of C.I. Pigment Red 3 in male B6C3F1 mice as exhibited by the increased incidences of tubule adenomas of the renal cortex and follicular cell adenomas of the thyroid gland. There was no evidence of carcinogenic activity of C.I. Pigment Red 3 in female B6C3F1 mice that received 12,500, 25,000, or 50,000 ppm. The incidences of mononuclear cell leukemia and preputial gland tumors in male rats and mononuclear cell leukemia, mammary gland fibroadenoma, and clitoral gland tumors in female rats were lower in the exposed groups. The incidences of liver foci were markedly increased in exposed male and female rats. The severity of chronic nephropathy was increased in male rats and to a lesser extent in female rats given C.I. Pigment Red 3. An increase in the severity of nephropathy was observed in male and female mice; cytomegaly (karyomegaly) of renal tubule epithelium was observed in male mice. Thyroid follicular cell hyperplasia occurred with an increased incidence in male and female mice receiving C.I. Pigment Red 3. Synonyms: 2-Naphthalenol, 1-((4-methyl-2-nitrophenyl)azo)-; Calcotone Toluidine Red YP; Fast Red A; Pigment Scarlet R; Recolite Fast Red RBL; Sengale Light Red B
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PMID:Toxicology and Carcinogenesis Studies of C.I. Pigment Red 3 (CAS No. 2425-85-6) in F344/N Rats and B6C3F1 Mice (Feed Studies). 1262 23

Mirex (95% pure), formerly used a systemic insecticide and as a fire retardant, was studied for toxicologic and carcinogenic effects by administering diets containing 0, 0.1, 1.0, 10, 25, or 50 ppm mirex to groups of 52 F344/N rats of each sex for 104 weeks. Doses selected for the 2-year studies were based primarily on the effects on body weights and survival of rats in a 26-week study. During the first 6 months of the 2-year study, because of good survival and the absence of observable toxic effects in female rats, additional groups (termed second study) of 52 F344/N female rats were started at higher dietary concentrations of 0, 50, and 100 ppm mirex. Based on feed consumption data, the estimated average intake per day was 0, 0.007, 0.075, 0.75, 1.95, and 3.85 mg mirex/kg body weight for male rats and female rats in the first study, and 0, 3.9, and 7.7 mg/kg for female rats in the additional study. Body Weights, Feed Consumption, and Survival in Two-Year Studies: Mean body weights of male rats that received 25 or 50 ppm mirex were 5%-18% lower than those of the controls throughout most of the study; mean body weights of female rats that received 50 or 100 ppm mirex were 4%-18% lower than those of the controls after week 40; mean body weights of groups receiving 0.1, 1.0, or 10 ppm were similar to those of controls. Feed consumption by dosed male rats was 83%-91% that by controls, and that by dosed female rats was 86%-99% that by controls. The top dietary exposure groups of rats received the equivalent of 3.85 mg mirex/kg body weight, whereas the 100-ppm group of female rats (second study) averaged 7.7 mg/kg. At the end of the study, survival of male rats that received 25 or 50 ppm of mirex was lower than that of controls, whereas survival of all dosed groups of female rats was similar to that of controls (male: control, 44/52; 0.1 ppm, 37/52; 1 ppm, 36/52; 10 ppm, 37/52; 25 ppm, 19/52; 50 ppm, 15/52; female-- first study: 38/52; 38/52; 35/52; 41/52; 35/52; female-- second study: control, 44/52; 50 ppm, 44/52; 100 ppm, 39/52). Nonneoplastic and Neoplastic Effects in the Two-Year Studies: The most notable compound-related effects were observed in the liver of male and female rats. Fatty metamorphosis, cytomegaly, angiectasis (males only), and necrosis of the liver were observed at increased incidences in dosed rats. The incidences of of neoplastic nodules of the liver were dose related, and in the 10-, 25-, and 50-ppm groups of males and the 50- and 100-ppm groups of females (second study), they were markedly greater than those in controls (52/group-- male: control, 3; 0.1 ppm, 5; 1 ppm, 5;10 ppm, 14; 25 ppm, 15; 50 ppm, 26; female (second study): control, 2; 50 ppm, 23; 100 ppm, 30). In the first study in female rats, the incidences of neoplastic nodules were not significantly different between control and dosed groups (10; 5; 4; 5; 9; 7). The 10 neoplastic nodules of the liver seen in the control group (19%) was significantly greater than the mean incidence observed historically (57/2,015; 2.8%). The incidences of hepatocellular carcinomas in control and dosed groups were relatively low and were not significantly different between groups. The incidences of pheochromocytomas of the adrenal gland occurred with a positive trend in male rats (8/51; 7/52; 13/52; 11/52; 18/51, 19/51); the incidences in the 25- and 50-ppm male rats were greater than that in controls; malignant pheochromocytomas were observed in 2 controls and in 2 mirex-exposed male rats. The incidence of pheochromocytomas in 50-ppm female rats in the first study was marginally greater than that in controls (control, 1/51; 50 ppm, 6/52); this borderline increase was not observed in the second female rat study and thus is not considered to be due to the dietary administration of mirex. Nephropathy occurred at similar incidences in control and mirex-exposed groups of male and female rats; however, the severity of this nonneoplastic lesion was judged to be slightly greater in the groups given 25, 50, or 100 ppm mirex (male: severe vs. moderate in controls; femas given 25, 50, or 100 ppm mirex (male: severe vs. moderate in controls; female: moderate to severe vs. moderate). Hyperplasia of the transitional epithelium of the kidney pelvis was observed in dosed male rats (0/51; 2/51; 2/52; 5/52; 14/51; 9/52). Transitional cell papillomas of the renal pelvis in male rats occurred with a positive trend (P<0.02) (0/51; 0/51; 0/52; 1/51; 3/52). The highest incidence previously observed in untreated male F344/N rats in NTP studies is 1/48, and the mean historical incidence is 5/1,968 (0.3%). In both the first and second studies in female rats, the incidence of mononuclear cell leukemia showed dosed-related increases (first study: 8/52; 8/52; 11/52; 14/52; 18/52; 18/52; second study: 6/52; 9/52; 14/52). When the data from both studies are combined, the incidences are significantly increased in the 10-, 25-, 50-, and 100-ppm groups. The mean historical incidence is 19% (375/2,021). For the thyroid gland, there was a positive trend for follicular cell neoplasms in male rats (0/51; 1/50; 0/47; 1/47; 0/35; 4/49) and a negative trend for C-cell neoplasms in male rats (8/51; 6/50; 4/47; 7/47; 3/35; 0/49) and infemale rats in the first study (12/50; 13/50; 7/48; 9/47; 6/48; 2/46). Neither observation is considered to be associated with the dietary administration of mirex. Genetic Toxicology: Mirex was not mutagenic in the Salmonella typhimurium-microsome assay when tested in a preincubation protocol in the presence or absence of exogenous metabolic activation in strains TA98, TA100, TA1535, or TA1537. Mirex did not induce either sister chromatid exchanges or chromosomal aberrations in Chinese hamster ovary cells in the presence or absence of S9. Conclusions: Under the conditions of these 2-year feed studies of mirex, there is clear evidence of carcinogenic activity for male and female F344/N rats, as primarily indicated by marked increased incidences of benign neoplastic nodules of the liver, as well as by increased incidences of pheochromocytomas of the adrenal gland and transitional cell papillomas of the kidney in males and by increased incidences of mononuclear cell leukemia in females. Nonneoplastic effects induced by mirex include cytomegaly, fatty metamorphosis, angiectasis (males only), and cellular necrosis in the liver. Synonyms and Trade Names: 1,1a,2,2,3,3a,4,5,5,5a,5b,6-dodecachlorooctahydro-1,3,4-metheno-1H-cyclobta[cd]pentalene; hexachloropentadiene dimer; dodecachloropentacyclodecane; perchloropentacyclodecane; hexachlorocyclopentadiene dimer; Dechloranereg.; Ferriamicidereg.
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PMID:NTP Toxicology and Carcinogenesis Studies of Mirex (1,1a,2,2,3,3a,4,5,5,5a,5b,6-Dodecachlorooctahydro-1,3,4- metheno-1H-cyclouta[cd]pentalene) (CAS No. 2385-85-5) in F344/N Rats (Feed Studies). 1274 40