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Inhalation oncogenicity bioassay in rats and mice with vinyl fluoride.

The purpose of this study was to assess the oncogenic potential of vinyl fluoride in rats and mice when administered by inhalation. Male and female rats and mice were exposed to 0, 25, 250, or 2500 ppm vinyl fluoride 6 hr per day, 5 days per week, for 2 years (rats) or 18 months (mice). Slight body weight gain decrements were noted in groups of vinyl fluoride-exposed rats and mice. No significant clinical signs of toxicity were noted other than an increase in the incidence of palpable masses in the region of the mammary gland in female mice exposed to vinyl fluoride. Survival was decreased in male rats and mice of the 250 and 2500 ppm groups and female rats and mice of all vinyl fluoride-exposed groups compared to controls. Urinary fluoride excretion, an indicator of vinyl fluoride metabolism, increased with concentration and time although the dose relationship appeared to plateau at concentrations > or = 250 ppm. Gross observations made at necropsy of rats supported histological observations of hepatic hemangiosarcoma, hepatocellular adenoma and carcinoma, hepatic foci of clear cell and basophilic alteration, hepatic sinusoidal dilatation, metastatic lung tumors, and Zymbal's gland tumors. Hepatic hemangiosarcoma was the sentinel lesion in rats. Gross observations made at necropsy of mice supported histological observations of bronchioloalveolar adenoma and hyperplasia, hepatic hemangiosarcoma and hepatocellular hyperplasia with angiectasis and peliosis, and mammary gland adenocarcinoma and hyperplasia. Bronchioloalveolar adenoma appeared to be the sentinel lesion in mice. The spectrum of vinyl fluoride-induced tumors is similar to that induced by other monohaloethylenes in rats and mice. Under the conditions of this study, vinyl fluoride was carcinogenic in male and female rats and mice at concentrations greater than or equal to 25 ppm.

Administration, Inhalation↗

Effect of ethanol on the tumorigenicity of urethane (ethyl carbamate) in B6C3F1 mice.

Urethane is a carcinogen to which there is widespread exposure through the consumption of fermented foods and alcoholic beverages. In this study, we have assessed the carcinogenicity of urethane in combination with ethanol. Male and female B6C3F(1) mice (48 mice per sex per group) were exposed to 0, 10, 30, or 90 ppm urethane in the presence of 0%, 2.5%, or 5% ethanol in drinking water ad libitum for two years, at which time the extent of tumorigenesis was assessed. Additional mice (four per sex per group) received the same doses for four weeks to assess serum levels of urethane and ethanol, DNA adduct formation, and the induction of microsomal cytochromes P450, cell proliferation, and apoptosis. Urethane decreased cell replication in the livers of female, but not male, mice, decreased cell replication in the lungs of both sexes, and induced cytochrome P450 2E1 in the livers of female mice. Hepatic levels of the DNA adduct 1,N(6)-ethenodeoxyadenosine were increased by exposure to urethane and decreased by treatment with ethanol. Animal weights and survival were not affected by ethanol; in contrast, urethane administration decreased body weights and survival. Urethane caused dose-dependent increases in liver, lung, and harderian gland adenoma or carcinoma and hemangiosarcoma of the liver and heart in both sexes, mammary gland and ovarian tumors in females, and squamous cell papilloma or carcinoma of the skin and forestomach in males. The increase in hepatocellular tumors occurred in a relatively linear manner and was attributed to the formation of 1,N(6)-ethenodeoxyadenosine in hepatic DNA coupled with an increase in cell replication. Hemangiosarcomas were observed only at the 90 ppm urethane dose and were probably a result of high-dose urethane-induced toxicity. Lung alveolar/bronchiolar and harderian gland adenoma or carcinoma increased in a relatively linear manner, suggestive of a genotoxic mechanism for tumor induction. Ethanol induced a dose-dependent trend in hepatocellular adenoma or carcinoma in male mice, with the incidence being marginally increased at the highest dose. In female mice administered 10 ppm and 90 ppm urethane, ethanol caused dose-related increases in alveolar/bronchiolar adenoma or carcinoma and hemangiosarcoma of the heart, respectively. This may be due to ethanol decreasing the first-pass clearance of urethane, thus, increasing systemic distribution. In male mice a different relationship was observed: ethanol caused a dose-related decrease in alveolar/bronchiolar and harderian gland adenoma or carcinoma in mice administered 30 ppm urethane.

Animals↗

Susceptibility to vascular neoplasms but no increased susceptibility to renal carcinogenesis in Vhl knockout mice.

The von Hippel-Lindau (VHL) tumor suppressor gene plays a prominent role in the development of renal cell carcinoma (RCC) in humans. VHL functions as a ubiquitin E3 ligase, controlling the stability of hypoxia inducible factor (HIF) and tumor angiogenesis. Alterations in this tumor suppressor gene are rarely observed in spontaneous or chemically induced RCC that arise in conventional strains of rodents and Vhl knockout mice (Vhl+/-) do not develop spontaneous RCC. We tested whether Vhl knockout mice exhibited increased susceptibility to renal carcinogenesis using the well-characterized renal carcinogen streptozotocin. No differences were observed between wild-type and Vhl+/- animals in the frequency or type of renal lesions induced by 50-200 mg/kg streptozotocin. Carcinogen-induced RCC that developed in Vhl heterozygotes and wild-type mice did not contain mutations in the wild-type Vhl, as determined by direct sequencing of the primary tumors. While Vhl+/- mice exhibited no increase in renal lesions in response to streptozotocin, heterozygous animals did develop vascular proliferative lesions of the liver, uterus, ovary, spleen and heart. These lesions, ranging from angiectasis to hemangiosarcoma, were most prominent in the livers of Vhl+/- mice, where they were found in high incidence and high multiplicity. Wild-type mice developed a low-frequency of liver angiectasis (7-15%) only at the highest doses of carcinogen used (150 and 200 mg/kg, respectively) while Vhl+/- mice exhibited angiectasis, hemangioma and hemangiosarcomas with a frequency ranging from 19 to 46% at 50-200 mg/kg streptozotocin. Untreated Vhl+/- mice had a spontaneous incidence of hepatic vascular lesions of 21%. Furthermore, vascular lesions of the uterus, ovary, spleen and heart were observed only in Vhl+/- mice, with an incidence of (5-28%). Taken together, the data indicate that heterozygosity at the Vhl locus predisposes mice to a vascular phenotype ranging from angiectasis to hemangiosarcoma, consistent with the ability of this tumor suppressor gene to control the stability of HIF and regulate key proteins that participate in angiogenesis.

Animals↗

Antigen expression in normal and neoplastic canine tissues defined by a monoclonal antibody generated against canine mesothelioma cells.

Monoclonal antibody (MAb) 3B5 generated against canine mesothelioma cells was applied to canine tumors and normal tissues via immunohistochemical and immunoblotting techniques to evaluate antigen binding. By use of an avidin-biotin immunoperoxidase complex (ABC) method, immunoreactivity was noted in reactive mesothelial cells and in normal tissues was observed primarily in mesothelial cell linings, endothelial cells, and smooth muscle of blood vessels and soft tissues; the reactivity was nearly equivalent in frozen or formalin-fixed, paraffin-embedded tissue sections. Use of the ABC method on formalin-fixed, paraffin-embedded tumors yielded moderate to strong cytoplasmic immunostaining of neoplastic cells in 10/11 (91%) mesotheliomas, 18/23 (78%) hemangiosarcomas, 4/10 (40%) intestinal and lung carcinomas, and < or = 20% of hemangiomas, leiomyosarcomas, leiomyomas, mammary carcinomas, and squamous cell carcinomas. No immunostaining of tumor cells was observed in fibrosarcomas, hemangiopericytomas, perianal gland carcinomas, and melanomas. Immunoblotting was performed on samples that demonstrated strong immunoreactivity with MAb 3B5 by the ABC method: mesothelioma, hemangiosarcoma, urinary bladder (smooth muscle), and lung (alveolar capillaries). These analyses showed that MAb 3B5 bound a major antigen of 78 kilodaltons (kd) and minor antigens at 56 and 54 kd in normal and neoplastic tissues. The preliminary immunohistochemical results suggest that MAb 3B5 may possess utility in diagnosis of mesotheliomas and hemangiosarcomas, discrimination of cell types in proliferative serosal lesions, and demonstration of vascularity or angiogenesis in neoplastic and inflammatory lesions.

Animals↗

NTP Toxicology and Carcinogenesis Studies of Cobalt Sulfate Heptahydrate (CAS No. 10026-24-1) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).

Cobalt sulfate is used in the electroplating and electro chemical industries. It is also used as a coloring agent for ceramics and as a drying agent in inks, paints, varnishes, and linoleum. Cobalt sulfate may be added to animal feed as a mineral supplement and has been used as a top dressing on pasture lands. Cobalt sulfate was nominated by the National Cancer Institute for study based on a lack of information on the toxicity of soluble salts. Male and female F344/N rats and B6C3F1 mice were exposed to cobalt sulfate heptahydrate (approximately 99% pure) by inhalation for 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium. The results of prechronic inhalation toxicity studies were reported previously (Bucher et al., 1990; NTP, 1991). 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were exposed to aerosols containing 0, 0.3, 1.0, or 3.0 mg/m3 cobalt sulfate heptahydrate 6 hours per day, 5 days per week, for 105 weeks. Survival and Body Weights Survival of exposed males and females was similar to that of the chamber controls. Mean body weights of exposed male and female rats were similar to those of the chamber controls throughout the study. Pathology Findings The incidences and severities of proteinosis, alveolar epithelial metaplasia, granulomatous alveolar inflammation, and interstitial fibrosis were markedly greater in all exposed groups of male and female rats than in the chamber controls. The incidences of alveolar epithelial hyperplasia in all groups of exposed males and in females exposed to 3.0 mg/m3 were significantly greater than those in the chamber control groups, as were the incidences of squamous metaplasia in 1.0 mg/m3 females and atypical alveolar epithelial hyperplasia in 3.0 mg/m3 females. In 3.0 mg/m3 males, the combined incidence of alveolar/ bronchiolar neoplasms (adenoma and/or carcinoma) was significantly greater than in the chamber controls. In female rats exposed to 1.0 or 3.0 mg/m3, the incidences of alveolar/bronchiolar neoplasms were significantly greater than those in the chamber control group and exceeded the NTP historical control ranges. A squamous cell carcinoma was observed in one 1.0 mg/m3 and one 3.0 mg/m3 female. The incidences of benign, complex, or malignant pheochromocytoma (combined) in 1.0 mg/m3 males and in 3.0 mg/m3 females were significantly greater than those in the chamber controls and exceeded the historical control ranges. Hyperplasia of the lateral wall of the nose, atrophy of the olfactory epithelium, and squamous metaplasia of the epiglottis were observed in all exposed groups of males and females, and the severities of these lesions increased with increasing exposure concentration. The incidences of squamous metaplasia of the lateral wall of the nose and metaplasia of the olfactory epithelium were increased in 3.0 mg/m3 males and females. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female mice were exposed to aerosols containing 0, 0.3, 1.0, or 3.0 mg/m3 cobalt sulfate heptahydrate 6 hours per day, 5 days per week, for 105 weeks. Survival and Body Weights Survival of exposed males and females was similar to that of the chamber controls. Mean body weights of 3.0 mg/m3 male mice were less than those of the chamber controls from week 96 until the end of the study. The mean body weights of all exposed groups of female mice were generally greater than those of the chamber controls from week 20 until the end of the study. Pathology Findings The incidences of diffuse histiocytic cell infiltration in 3.0 mg/m3 males and of focal histiocytic cell infil tration in 3.0 mg/m3 females were significantly greater than those in the chamber controls. The incidences of alveolar/bronchiolar neoplasms in 3.0 mg/m3 males and females were significantly greater than those in the chamber control groups. The combined incidences of alveolar/bronchiolar adenoma or carcinoma and the incidences of alveolar/bronchiolar carcinoma in 3.0 mg/m3 males and females and the incidence of alveolar/bronchiolar adenoma in 3.0 mg/m3 females exceeded the NTP historical crical control ranges for inhalation studies. The incidences of atrophy of the olfactory epithelium in 1.0 and 3.0 mg/m3 males and females and hyper plasia of the olfactory epithelium in 3.0 mg/m3 males and females were significantly greater than in the chamber controls. Squamous metaplasia of the larynx was observed in all exposed groups of males and females. Male mice had a pattern of nonneoplastic liver lesions along with silver-staining helical organisms within the liver, characteristic of an infection with Helico bacter hepaticus. In NTP studies with H. hepaticus- associated hepatitis, increased incidences of hemangiosarcoma were seen in the liver of male mice. In this study of cobalt sulfate heptahydrate, incidences of hemangiosarcoma were increased in exposed groups of male mice. Because of the above association, interpretation of the increased incidences of hemangiosarcoma in the livers of male mice was confounded. Incidences of lesions at other sites in this study of cobalt sulfate heptahydrate were not considered to have been significantly impacted by the infection with H. hepaticus or its associated hepatitis. GENETIC TOXICOLOGY: Cobalt sulfate heptahydrate was mutagenic in S. typhimurium strain TA100 with and without liver S9 metabolic activation enzymes; no mutagenic activity was detected in strain TA98 or TA1535, with or without S9. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was some evidence of carcinogenic activity of cobalt sulfate heptahydrate in male F344/N rats based on increased incidences of alveolar/bronchiolar neoplasms. Marginal increases in incidences of pheochromocytomas of the adrenal medulla may have been related to exposure to cobalt sulfate heptahydrate. There was clear evidence of carcinogenic activity in female F344/N rats based on increased incidences of alveolar/bronchiolar neo-plasms and pheochromocytomas of the adrenal medulla in groups exposed to cobalt sulfate heptahydrate. There was clear evidence of carcinogenic activity of cobalt sulfate heptahydrate in male and female B6C3F1 mice based on increased incidences of alveolar/bronchiolar neoplasms. Exposure to cobalt sulfate heptahydrate caused a spectrum of inflammatory, fibrotic, and proliferative lesions in the respiratory tract of male and female rats and mice. Synonyms: Bieberite; cobalt(II) sulfate (1:1) heptahydrate; cobalt monosulfate heptahydrate; cobalt(II) sulphate heptahydrate; sulfuric acid, cobalt(2+) salt (1:1) heptahydrate

Journal Article↗

NTP Toxicology and Carcinogenesis Studies of Two Pentachlorophenol Technical-Grade Mixtures (CAS No. 87-86-5) in B6C3F1 Mice (Feed Studies).

Toxicology studies of pentachlorophenol, a biocide used primarily as a wood preservative, were conducted by feeding diets containing a technical-grade composite, Dowicide EC-7 (a technical grade formulation), or pure pentachlorophenol to groups of B6C3F1 mice for 30 days. These three grades plus another commercial grade of pentachlorophenol (DP-2) were used in 6-month studies. These studies were followed by 2-year carcinogenicity studies of technical-grade pentachlorophenol and of Dowicide EC-7 in feed. Genetic toxicology studies were conducted in Salmonella typhimurium and in Chinese hamster ovary (CHO) cells. Thirty-Day and Sixteen-Month Studies: Groups of 19 male mice and 5-15 female mice were fed diets containing 0, 20, 100, 500, 2,500, or 12,500 ppm technical-grade pentachlorophenol, Dowicide EC-7, or pure pentachlorophenol for 30 consecutive days. Necropsies and histopathologic examinations were performed on all animals. Selected organs were weighed. Supplemental analyses included hematology, serum chemistry, urinalysis, immunology, and hepatic enzyme induction. Compound-related deaths were observed at the highest dose (12,500 ppm) with all three materials and at 2,500 ppm with EC-7 and pure pentachlorophenol (males only). Decreases in body weight gain were also observed in the groups in which deaths occurred. Diffuse centrilobular cytomegaly, karyomegaly, nuclear atypia, degeneration, or necrosis of the liver were compound-related lesions observed in all groups that received pure pentachlorophenol, technical-grade pentachlorophenol, or EC-7 at 500 ppm and above. Serum enzymes associated with liver injury were increased. In the 6-month studies, groups of 10 male and 10 female mice were given diets containing the various grades of pentachlorophenol at the following dietary concentrations: 200, 600, or 1,800 ppm technical-grade pentachlorophenol; 200, 600, or 1,200 ppm DP-2 (not used in the 30-day studies); 200, 600, or 1,200 ppm EC-7; or 200, 500, or 1,500 ppm pure pentachlorophenol for 26-27 weeks. Common control groups of 10 male and 10 female mice were fed control diets. Additional groups of male mice were examined for behavioral, histopathologic, clinical pathology, biochemical, and immunologic effects. All mice exposed at the highest dose of technical-grade pentachlorophenol died, as did 2/10 male mice exposed at the highest dose of DP-2. No deaths were observed in mice exposed to EC-7 or pure pentachlorophenol. Markedly lower final body weights were observed in the high dose groups only (all grades of pentachlorophenol). No chemical-relatedclinical signs were observed at sublethal doses. No major behavioral changes were observed after 5 weeks' exposure, but increased motor activity and heightened startle responses were present at the end of the study in female mice exposed to all four grades of pentachlorophenol. All grades of pentachlorophenol caused increases in serum enzymes associated with liver injury. All grades of pentachlorophenol also resulted in a dose-related induction of aryl hydrocarbon hydroxylase and an increase in cytochrome P450. However, the technical grade was a more powerful inducer than the other grades of pentachlorophenol. Pure pentachlorophenol had no effect on humoral or cell-mediated immunity. However, DP-2 and particularly technical-grade pentachlorophenol depressed humoral immune function. A dose-related increase in liver weight was observed in mice exposed to all grades of pentachlorophenol. A dose-related increase in spleen weight was observed in male mice exposed to all grades of pentachlorophenol; a decrease in spleen weight was observed in female mice exposed to all grades of pentachlorophenol except pure. After 6 months' exposure, histopathologic examination consistently revealed effects in the liver and urinary bladder. The liver lesions were present at all doses with all four grades of pentachlorophenol but were less severe at comparable doses in the mice exposed to pure pentachlorophenol; they consisted of hepatocellular karyomegaly, cytomegaly, and degeneration. The changes in the urinary bladder consisted of a brown granular pigment in the cells of the surface epithelium. No inflammation or proliferative response was associated with the pigment. Based primarily on the liver lesions observed in the 6-month studies, diets chosen for the 2-year studies contained 0, 100, or 200 ppm technical-grade pentachlorophenol or 0, 100, 200, or 600 ppm EC-7, fed to groups of 50 male and 50 female mice. DP-2 and pure pentachlorophenol were not chosen for the 2-year studies because of economic considerations and because the clinicopathologic syndrome observed in the 6-month studies was similar to that observed with EC-7. Body Weights and Survival in the Two-Year Studies: Mean body weights of mice exposed to technical-grade pentachlorophenol and EC-7 were comparable to those of controls until weeks 36-82. Thereafter, a 4&percnt;-22&percnt; dose-related decrease was observed in the mid and high dose mice exposed to EC-7 and in high dose mice exposed totechnical-grade pentachlorophenol. Females were more affected than males. Feed consumption by exposed mice was similar to that by controls. The average daily doses of technical-grade pentachlorophenol were approximately 17-18 or 35 mg/kg compared with 17-18, 34-37, or 114-118 mg/kg of EC-7. Survival of mice did not appear to be affected by exposure to either technical-grade pentachlorophenol or EC-7 at the doses used in these studies. Neoplastic and Nonneoplastic Effects in the Two-Year Studies: The incidences of hepatocellular adenomas and carcinomas were increased (dose related) in male and female mice exposed to either technical-grade pentachlorophenol or EC-7, although the increase was less marked in females exposed to technical-grade pentachlorophenol (adenomas or carcinomas, combined: technical-grade: male-- control, 7/32, 22&percnt;; low dose, 26/47, 55&percnt;; high dose, 37/48, 77&percnt;; female--3/33, 9&percnt;; 9/49, 18&percnt;; 9/50, 18&percnt;; EC-7: male--control, 6/35, 17&percnt;; low dose, 19/48, 40&percnt;; mid dose, 21/48, 44&percnt;; high dose, 34/49, 69&percnt;; female-- 1/34, 3&percnt;; 4/50, 8&percnt;; 6/49, 12&percnt;; 31/48, 65&percnt;). The incidences of pheochromocytomas in male mice were significantly greater than those in controls for both technical-grade pentachlorophenol (0/31; 10/45, 22&percnt;; 23/45, 51&percnt;) and EC-7 (1/34, 3&percnt;; 4/48, 8&percnt;; 21/48, 44&percnt;; 45/49, 92&percnt;). These neoplasms were also increased in female mice exposed to EC-7 at the highest dose (0/35; 2/49, 4&percnt;; 2/46, 4&percnt;; 38/49, 78&percnt;) but not in those exposed to technical-grade pentachlorophenol (2/33, 6&percnt;; 2/48, 4&percnt;; 1/49, 2&percnt;). Hyperplasia of the adrenal medulla was observed at increased incidences in mice that received either technical-grade pentachlorophenol (male: 1/31; 10/45; female: 0/33; 4/48; 2/49) or EC-7 (male: 1/34; 19/48; 13/48; 1/49; female: 2/35; 1/49; 5/46; 17/49). The incidences of hemangiosarcomas in the spleen and/or liver were significantly greater than those in controls for high dose female mice that received technical-grade pentachlorophenol (0/35; 3/50, 6&percnt;; 6/50, 12&percnt;) or EC-7 (0/35; 1/50, 2&percnt;; 3/50, 6&percnt;; 8/49, 16&percnt;). Compound-related nonneoplastic lesions occurred in the liver, spleen, and nose in mice exposed to either technical-grade pentachlorophenol or EC-7. The lesions in the liver included dose-related increased incidences of clear cell foci, chronic active inflammation, pigmentation, necrosis, cytomegaly, proliferation of hematopoietic cells, and bile duct hyperplasia. Increased amounts of extramedullary hematopoiesis of the splenic red pulp were observed at increased incidences in dosed male and high dose female mice that received technical-grade pentachlorophenol (male: 5/30; 15/23; 18/46; female: 2/33; 4/13; 11/47). Acutefocal inflammation of the nasal mucosa and focal metaplasia of the olfactory epithelium were observed at increased incidences in high dose mice that received EC-7 (inflammation--male: 4/35; 1/13; 3/16; 47/49; female: 0/35; 0/14; 2/5; 46/48; focal metaplasia-- male: 2/35; 1/13; 2/16; 46/49; female: 1/35; 0/14; 2/5; 45/48) but not in mice exposed to technical-grade pentachlorophenol. Genetic Toxicology: Pentachlorophenol (91.6&percnt; pure; equivalent in purity to the technical-grade pentachlorophenol used in the toxicology studies) was not mutagenic in S. typhimurium strains TA98, TA100, TA1535, or TA1537 when tested in the presence or absence of exogenous metabolic activation (S9). In cytogenetic studies with cultured CHO cells, pentachlorophenol produced an increase in chromosomal aberrations in the presence but not the absence of S9 metabolic activation; conversely, sister chromatid exchanges (SCEs) were induced only in the absence of S9. Audit: The data, documents, and pathology materials from the 2-year studies of pentachlorophenol have been audited. The audit findings show that the conduct of the studies is documented adequately and support the data and results given in this Technical Report. Conclusions: Under the conditions of these 2-year feed studies, there was clear evidence of carcinogenic activity for male B6C3F1 mice fed diets containing technical-grade pentachlorophenol, as shown by increased incidences of adrenal medullary and hepatocellular neoplasms. There was some evidence of carcinogenic activity for female B6C3F1 mice exposed to technical-grade pentachlorophenol, as shown by increased incidences of hemangiosarcomas and hepatocellular neoplasms. There was clear evidence of carcinogenic activity for male B6C3F1 mice exposed to pentachlorophenol, EC-7, as shown by increased incidences of adrenal medullary and hepatocellular neoplasms. There was clear evidence of carcinogenic activity for female B6C3F1 mice exposed to pentachlorophenol, EC-7, as shown by increased incidences of adrenal medullary and hepatocellular neoplasms and hemangiosarcomas. Chemically related increased incidences of nonneoplastic lesions in mice of each sex included hepatocellular cytomegaly, necrosis, inflammation, pigmentation, and clear cell foci and intrahepatic bile duct hyperplasia. Synonyms or Common Names: chlorophen; PCP; penchlorol; penta; pentachlorofenol; pentachlorofenolo; pentachlorphenol; 2,3,4,5,6-pentachlorophenol Trade Names: Acutox; Chem-Penta; Chem-Tol; Cryptogil ol; Dowicide 7; Dowicide EC-7; Dow Pentachlorophenol DP-2 Antimicrobial; Durotox; EP 30; Fungifen; Fungol; Glazd Penta; Grundier Arbezol; Lauxtol; Lauxtol A; Liroprem; Moosuran; Pentacon; Penta-Kil; Pentasol; Penwar; Peratox; Permacide; Permagard; Permasan;Permatox; Priltox; Permite; Santophen; Santophen 20; Sinituho; Term-i-Trol; Thompson's Wood Fix; Weedone; Witophen P

Journal Article↗

NTP Toxicology and Carcinogenesis Studies of Propylene Oxide (CAS no. 75-56-9) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).

Propylene oxide is a volatile, colorless liquid used as an intermediate in the production of polyether polyols, polyurethane foams, and unsaturated polyester resins and also as a fumigant for sterilizing a variety of materials ranging from plastic medical instruments to foodstuffs. In the United States, propylene oxide is registered as a fumigant for packaged dried prunes and glacé fruits such as candied cherries and as an insecticidal and fungicidal fumigant for bulk quantities of cocoa, gums, and processed spices. The 2-year carcinogenesis studies of propylene oxide (greater than 99.9% pure) were conducted by exposing groups of 50 F344/N rats and 50 B6C3F1 mice of each sex to air containing propylene oxide at concentrations of 0 (chamber control), 200, or 400 ppm for 6 hours per day, 5 days per week, for 103 weeks. The survival of rats exposed to propylene oxide was comparable with that of the controls; terminal body weights were lower than those of the controls for high dose males (8%) and high dose females (6%). Survival of exposed male and female mice decreased relative to that of the controls (male: control, 42/50; low dose, 34/50; high dose, 29/50; female: 38/50; 29/50; 10/50), but the difference was significant only for animals in the high dose groups. High dose female mice had a mean terminal body weight 22% below that of the controls. The respiratory epithelium of the nasal turbinates was one of the primary tissues affected in male and female rats; exposure-related increases occurred in the incidences of suppurative inflammation, epithelial hyperplasia, and squamous metaplasia. Papillary adenomas, involving the respiratory epithelium and underlying submucosal glands of the nasal turbinates, were observed in three female rats and two male rats exposed to propylene oxide at 400 ppm. The incidence of adenomas in females was significant by the trend tests. The proportions of high dose female rats with C-cell adenomas and with C-cell carcinomas of the thyroid gland were increased, but only the combined incidence of these tumors was significant (2/45; 2/35; 7/37). These tumors were not considered to be related to exposure to propylene oxide because there was no other evidence for C-cells' being a target tissue and because there was no increase in C-cell hyperplasia. The combined incidences of female rats with endometrial stromal polyps and endometrial stromal sarcomas of the uterus were significantly increased in the dosed groups (3/49; 12/50; 10/47). However, the occurrence of these lesions in the dosed groups was similar to the average (306/1,502, 20%) seen in untreated controls in NTP carcinogenesis studies, and hence this increase was not regarded as being related to exposure to propylene oxide. The respiratory epithelium of the nasal turbinates was also one of the primary tissues affected in male and female mice; exposure-related increases occurred in the incidences of inflammation, and squamous metaplasia was observed in one low dose male and two high dose female mice. One squamous cell carcinoma and one papilloma occurred in the nasal cavity of different high dose male mice, and two high dose female mice had adenocarcinomas of the nasal cavity. The endothelial cells of the submucosal vascular plexus in the nasal turbinates also appeared to be a major site affected in high dose male mice. Three high dose male and three high dose female mice had a saccular dilation (classified as angiectasis) of submucosal turbinate vessels. Further, hemangiomas were seen in the nasal cavity of 5/50 high dose male mice and 3/50 high dose female mice, and hemangiosarcomas were found in the nasal cavity of 5/50 high dose male mice and 2/50 high dose female mice. The increased incidences of hemangiomas in males and females and of hemangiosarcomas in males were statistically significant. Vascular tumors were not present in the nasal turbinates of any low dose or control mice. Under the conditions of these studies, there was some evidence of carcinogenicity for F344/N rats, as indicated by increased incidences of papillary adenomasncreased incidences of papillary adenomas of the nasal turbinates in male and female rats exposed to propylene oxide at 400 ppm. For male and female B6C3F1 mice, there was clear evidence of carcinogenicity, as indicated by increased incidences of hemangiomas or hemangiosarcomas of the nasal turbinates at 400 ppm. In the respiratory epithelium of the nasal turbinates, propylene oxide also caused suppurative inflammation, hyperplasia, and squamous metaplasia in rats and inflammation in mice.

Journal Article↗

NTP Toxicology and Carcinogenesis Studies of 1,3-Butadiene (CAS No. 106-99-0) in B6C3F1 Mice (Inhalation Studies).

1,3-Butadiene is used as an intermediate in the production of elastomers, polymers, and other chemicals. Of the 1,3-butadiene used in 1978, 44% was used to manufacture styrene-butadiene rubber (a substitute for natural rubber, produced by copolymerization of 1,3-butadiene with styrene), and 19% was used to produce polybutane elastomer (a substance that increases resistance of tire products to wear, heat degradation, and blowouts). Chloroprene monomer, derived from 1,3-butadiene, is used exclusively to manufacture neoprene elastomers for non-tire and latex applications. Commercial nitrile rubber, used largely in rubber hoses, seals, and gaskets for automobiles, is a copolymer of 1,3-butadiene and acrylonitrile. Acrylonitrile- butadiene- styrene resins, usually containing 20%-30% 1,3-butadiene by weight, are used to make parts for automobiles and appliances. Other polymer uses include specialty polybutadiene polymers, thermoplastic elastomers, nitrile barrier resins, and K resins(R). 1,3-Butadiene is used as an intermediate in the production of a variety of industrial chemicals, including two fungicides, captan and captofol. It is approved by the U.S. Food and Drug Administration for use in the production of adhesives used in articles for packaging, transporting, or holding food; in components of paper and paperboard that are in contact with dry food; and as a modifier in the production of semigrid and rigid vinyl chloride plastic food-contact articles. No information was located on the levels of monomer or on its elution rate from any of the commercially available polymers. It is not known if unreacted 1,3-butadiene migrated from packaging materials. Male and female B6C3F1 mice were exposed to air containing 1,3-butadiene (greater than 99% pure) at concentrations of 0-8,000 ppm in 15-day and 14-week inhalation studies. In the 15-day studies, survival was unaffected by dose, and no pathologic effects were observed; slight decreases in mean body weight occurred at the high concentrations. In the 14-week studies, mean body weight gain decreased with dose, and survival in the 5,000-ppm and 8,000-ppm groups of males was markedly reduced; no other compound-related effects were reported. Inhalation carcinogenesis studies of 1,3-butadiene were conducted by exposing groups of 50 male and female B6C3F1 mice 6 hours per day for 5 days per week to air containing the test chemical at concentrations of 0 (chamber controls), 625, or 1,250 ppm. These studies were planned for 103-week exposures but were terminated at week 60 for male mice and week 61 for female mice because of the rapidly declining survival, primarily due to neoplasia. Body weights were not affected by 1,3-butadiene. Significantly increased incidences of neoplasms at multiple sites were observed in mice exposed to 1,3-butadiene. Hemangiosarcomas of the heart occurred at increased incidences in exposed males and females (male: control, 0/50; low dose, 16/49; high dose, 7/49; female: 0/50; 11/48; 18/49). Hemangiosarcomas were also observed in the peritoneal cavity (one high dose male), subcutaneous tissue (two low dose females), and liver (one high dose female). Malignant lymphomas, diagnosed as early as week 20, were observed at increased incidences in exposed male and female mice (male: 0/50; 23/50; 29/50; female: 1/50; 10/49; 10/49). Alveolar/bronchiolar adenomas and alveolar/bronchiolar (both separately and combined) occurred at increased incidences in exposed male and female mice (combined incidences -- male: 2/50; 14/49; 15/49; female: 3/49; 12/48; 23/49). Epithelial hyperplasia of the forestomach occurred at increased incidences in dosed mice (male: 0/49; 5/40; 7/44; female: 0/49; 5/42; 9/49). Papillomas of the forestomach occurred in low dose male and in low dose and high dose female mice (male: 0/49; 5/40; 0/44; female: 0/49; 4/42; 10/49). Squamous cell carcinomas of the forestomach were observed in dosed mice (male: 0/49, 2/40, 1/44; female: 0/49, 1/42, 1/49). Acinar cell carcinomas of the mammary gland were observed at an increased incidence in high dose female reased incidence in high dose female mice (0/50; 2/49; 6/49); adenosquamous carcinomas were found in four low dose females. The incidences of granulosa cell tumors of the ovary were increased in dosed females (0/49; 6/45; 12/48). A granulosa cell carcinoma was observed in another high dose female. Gliomas were observed in two 68- to 69-week-old low dose and one high dose male mice; brain tumors are uncommon even in 2-year old mice. Liver necrosis occurred at increased incidences in dosed male and low dose female mice (male; 1/50, 8/49, 8/49; female: 6/50, 15/47, 6/49). Hepatocellular adenomas or carcinomas (combined) were observed at an increased incidence in high dose female mice (0/50, 2/47 5/49). No neoplastic lesions of the nasal cavity were observed at any dose level. The following nonneoplastic lesions of the nasal cavity occurred in mice exposed at 1,250 ppm: chronic inflammation (male, 35/50; female, 2/49); fibrosis (male, 33/50; female, 2/49); cartilaginous metaplasia (male, 16/50; female, 1/49); osseous metaplasia (male, 11/50; female, 2/49); and atrophy of the sensory epithelium (male, 32/50). No nonneoplastic lesions of the nasal cavity were found in the controls. The incidence of testicular atrophy (0/50, 19/49, 11/48) or ovarian atrophy (2/49, 40/45, 40/48) was increased in exposed male or female mice. An audit of the experimental data from these studies on 1,3-butadiene was conducted by the National Toxicology Program. No data discrepancies were found that influenced the final interpretation of these experiments. Under the conditions of these studies, there was clear evidence of carcinogenicity for 1,3-butadiene in male and female B6C3F1 mice, as shown by increased incidences and early induction of hemangiosarcomas of the heart, malignant lymphomas, alveolar/bronchiolar adenomas and carcinomas, and papillomas of the stomach in males and females; and of acinar cell carcinomas of the mammary gland, granulosa cell tumors of the ovary, and hepatocellular adenomas and adenomas or carcinomas (combined) in females. 1,3-Butadiene was associated with nonneoplastic lesions in the respiratory epithelium, liver necrosis, and testicular or ovarian atrophy. Synonyms: butadiene; biethylene; bivinyl; divinyl; erythrene; vinylethylene; pyrrolylene

Journal Article↗

[Soft tissue sarcoma in the head and neck--analysis of 87 patients].

From 1964 to 1984, 87 patients with soft tissue sarcoma (excluding lymphreticulum system sarcoma) in the head and neck were treated in our hospital. All were proved by pathology. The incidence rate of fibrosarcoma was the highest (36.8%), hemangiosarcoma the lowest (5.8%). There was no liposarcoma or synovial sarcoma in this group. The most frequently involved site was the area near the nasal cavity and maxillary sinus for fibrosarcoma (66%), the base of tongue for hemangiosarcoma (60%), scalp for dermatofibrosarcoma protuberans (54%), parapharyngeal space and soft tissue of the neck for neurogenic sarcoma (45%). Metastasis rate to the lymph nodes was 16-20% for rhabdomyosarcoma, hemangiosarcoma and malignant fibrohistiocyte tumor. No distant metastasis was found in dermatofibrosarcoma protuberans and malignant fibrohistiocyte tumor. Distant metastasis rate was 10-20% for the other types. Local recurrence rate was 9.1% for dermatofibrosarcoma protuberans, 88.9% for malignant fibrohistiocyte tumor, 30-66.7% for the other sarcomas. The 5- and 10-year survival rates were 20% and 0%, 37.5% and 0%, 91.6% and 91.6% for rhabdomyosarcoma, malignant fibrohistiocyte tumor and dermatofibrosarcoma protuberans. There were differences in clinical behavior for soft tissue sarcomas in the head, neck and in the trunk. Highly malignant sarcomas, such as liposarcoma, synovial sarcoma and rhabdomyosarcoma were rare in the head and neck but the low malignant sarcomas in the head and neck were 3-10 times as common as those in the trunk. Distant metastasis rate of the fibrosarcoma was 20% in head and neck and 6.7%in trunk, the 5- and 10-year survival rates were 36% and 77.9%, 25% and 73.6%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

Comparative pathology of bone tumors in animals, with particular emphasis on the dog.

A review of bone tumors in animals, based on cases reported in the literature and on personal examination of cases from several universities in the U.S.A. and Europe, has shown that: 1. The following bone tumors occur in decreasing order of frequency in animals: osteosarcoma, chondrosarcoma, osteochondroma, hemangiosarcoma, fibrosarcoma, and liposarcoma; 2. The dog has by far the highest frequency of bone tumors; and osteosarcomas account for approximately 80 percent of bone tumors in dog, followed by chondrosarcomas and hemangiosarcomas; 3. Bone tumors occur less frequently in the cat than in the dog, and are of essentially the same types and incidence as in the dog; 4. Sheep has a unique propensity for chondrosarcoma and primary bone tumors are rare in other species; 5. Giant cell tumors, reticulum cell sarcomas, and Ewing's sarcomas are exceptional findings in animals.

Animals↗

An experimental study of intraoral carcinogenesis in rats.

A new method has been devised for preparing artificial cecal pouches lined with mucous epithelium in the lower lips of Wistar and Sprague-Dawley rats in order to make carcinogens act continuously for a long time in the oral mucosa. When a 0.5 per cent mineral oil solution of DMBA, a crystal of MC, and a crystal of NG were administered, squamous-cell carcinoma, carcinoma in situ, papilloma, adenoma sebaceum. neurofibroma, fibroma, hemangiosarcoma, hemangiosarcoma, hemangioma, and lymphangioma were successfully produced in the oral mucosa of rats. In addition, interesting findings were obtained concerning tissue changes in the process of carcinogensis in the mucous epithelium.

Animals↗

Toxicity and carcinogenicity of riddelliine in rats and mice.

These investigations of riddelliine analyzed potential carcinogenesis and the utility of the female-rat/male-mouse design in bioassays and dose-response. Groups of 50 Fischer rats and B6C3F1 mice were gavage-administered riddelliine 5 days per week for 105 weeks. The dose levels for male rats were 0 or 1.0 mg/kg body weight; female rats 0, 0.01, 0.033, 0.1, 0.33, or 1.0 mg/kg; male mice 0, 0.1, 0.3, or 1.0, 3.0 mg/kg; and female mice 0 or 3.0 mg/kg. The dose groups were purposely designed to evaluate the dose-response relationship only in female rats and male mice. In rats, liver hemangiosarcoma, hepatocellular adenoma, and mononuclear cell leukemia were significantly increased in the 1.0 mg/kg male and female dose groups. Non-neoplastic lesions occurred in the liver and kidney of male and female rats. In mice, hemangiosarcomas increased significantly in the liver of males in the 3.0 mg/kg dose group. Alveolar/bronchiolar neoplasms in the 3.0 mg/kg dose group of female mice were significantly increased. Hepatocellular neoplasms were significantly decreased in the 1.0 mg/kg dose group of male and 3.0 mg/kg dose groups of male and female mice. Non-neoplastic lesions occurred in the liver and kidney of male and female, and lung and arteries of female mice. These studies demonstrate toxicity and carcinogenicity of riddelliine in rats and mice, and a dose-response relationship in female rats and male mice under the experimental conditions employed.

Animals↗

Primary liver tumors in the pediatric age group: an angiographic challenge.

Eleven children, ranging in age from three months to fifteen years, with primary liver tumors were examined by large volume direct magnification arteriography (2.5--3 ml of contrast material per 1 kg body weight for a single selective study). The following tumors were found: hepatoblastoma (1), hepatocellular carcinoma of the adult type, hepatoma (3), infantile hemangioendothelioma (4), hemangiosarcoma (1), focal nodular hyperplasia (1) and cystic mesenchymal hamartoma (1). Some of the tumors have a quite typical angiographic appearance as infantile hemangioendothelioma, hemangiosarcoma, cystic mesenchymal hamartoma. The other highly vascular neoplasms show unspecific signs of vascular malignant tumors; subtile angiographic signs may, however, be present and help in the differential diagnosis.

Adolescent↗

Lifespan studies in rats exposed to 239PuO2 aerosol. III. Survival and lung tumours.

Female, young adult, Wistar rats were given a single inhalation exposure to a submicron sized aerosol of high-fired 239PuO2 and observed during their lifespan for primary lung tumours. Rats were distributed among sham-control (n = 1052) and exposed (n = 2105) groups. Survival was significantly reduced only in rats with lung doses > 30 Gy. A total of 99 primary lung tumours were found, of which 92% were malignant and 80% were carcinomas. Of malignant lung tumours, 49 were squamous cell carcinoma, 23 adenocarcinoma, nine hemangiosarcoma, seven adenosquamous carcinoma, and three fibrosarcoma. One adenocarcinoma was found in controls and only four adenomas were seen in the exposed rat at lung doses < 1.5 Gy. The lowest doses at which lung tumours appeared in exposed rats were 1.5 Gy for squamous cell carcinoma, 3.1 Gy for adenocarcinoma. 4.1 Gy for hemangiosarcoma, and about 9 Gy for adenosquamous carcinoma and fibrosarcoma. Pulmonary squamous metaplasia was not seen in controls and was first seen in exposed rats only at lung doses > 1 Gy. Primary lung tumours were the presumed cause of death (fatal) in 60% of rats with malignant lung tumours; causes of death were equally distributed among all tumour types and doses. The incidence of all lung tumours was 0.095% in control rats, 0.21% in 1877 rats with lung doses < 1 Gy, and 41% in 228 rats with doses > 1 Gy. Lung tumour incidence increased in a linear manner from 6.9% at 2.3 Gy to an incidence of 64-88% at 16-44 Gy. Absolute malignant lung tumour risk averaged 270 lung tumours per 10(4) rat-Gy above a lung dose of 1 Gy. All types of malignant lung tumours induced by inhaled 239PuO2 exhibited a threshold at a lung dose > 1 Gy.

Adenocarcinoma↗

Review of studies concerning the tumorigenicity of 2-butoxyethanol in B6C3F1 mice and its relevance for human risk assessment.

The U.S. National Toxicology Program (NTP) has completed 2-yr inhalation exposures in rats and mice with 2-butoxyethanol (BE). This review concerns the most significant findings from those studies and describes recent research into the mechanistic aspects of BE-mediated tumorigenesis in the mouse and the relevance of such effects to humans. Two tumor types were increased in B6C3F1 mice leading to the classification of "some evidence" of carcinogenicity: liver hemangiosarcomas in male mice and forestomach tumors in female mice (primarily benign papillomas). The results of research collected to date indicate that the tumorigenesis noted for BE was produced by indirect mechanisms. In particular, the occurrence of liver hemangiosarcomas in male mice has been linked to oxidative damage subsequent to red blood cell hemolysis and iron deposition in this organ. Oral administration of BE in mice up to 600 mg/kg/d for up to 90 d produces a dose-related increase in iron (Perl's staining) in Kupffer cells and hepatocytes, increased DNA synthesis in endothelial cells, and enhanced oxidative damage. Further, iron alone, and not BE or BAA, is responsible for producing oxidative damage in cultured hepatocytes from rats or mice. Forestomach neoplasms in female mice were most likely a result of prolonged exposure-induced irritation with compensatory hyperplasia and subsequent tumor promotion. This mechanism is supported by studies indicating elevated levels of BE and BAA in the mouse forestomach tissues and stomach contents following multiple routes of exposure, forestomach epithelial cell cytotoxicity and cell proliferation following administration of BE and BAA, and the increased capacity of forestomach tissues from female mice to metabolize BE to the more irritating metabolite, BAA. The current article summarizes the results of a number of in vivo and in vitro studies designed to elucidate the underlying mechanisms of tumorigenesis by BE in the mouse and discusses the relevance of these for human risk.

Administration, Oral↗

Increased susceptibility of poly(ADP-ribose) polymerase-1 knockout mice to nitrosamine carcinogenicity.

The involvement of poly(ADP-ribose) polymerase-1 (Parp-1), one of the poly(ADP-ribose) polymerase family proteins, in genomic stability, DNA repair and cell death triggered by DNA damage has been well documented. However, the potential role of Parp-1 in carcinogenesis has not been well evaluated. In this study the carcinogenic activity of N:-nitrosobis(2-hydroxypropyl)amine (BHP) was studied in Parp-1(-/-) mice, generated by disrupting P:arp-1 gene exon 1. Parp-1(-/-) and Parp-1(+/+) male mice received 0, 250 and 500 p.p.m. BHP in their drinking water for 20 weeks and were then killed. The percentage of animals bearing hemangiomas and hemangiosarcomas in the liver and numbers of tumors per mouse were markedly higher in the Parp-1(-/-) groups given 250 or 500 p.p.m. BHP than in their Parp-1(+/+) counterparts. Hemangiosarcomas developed only in Parp-1(-/-) mice. In the lung the numbers of adenomas per mouse were increased in Parp-1(-/-) mice given BHP at 250 and 500 p.p.m. (P < 0.01) compared with the Parp-1(+/+) case. The results show that susceptibility to BHP is significantly elevated in Parp-1(-/-) mice, thus providing direct evidence that Parp-1 is relevant to carcinogenesis.

Adenocarcinoma↗

Effect of lifetime exposure to aflatoxin b1 in rats.

Aflatoxin B1 was fed at 2 ppm in the diet to a group of pregnant F344 rats from the time of conception; it was then fed to their offspring until death. This diet was also given to another group of rats 6-7 weeks old for comparison. The survival time of male rats was significantly shorter than that of the female rats of both groups. However, the survival times of rats of the same sex in both groups did not differ significantly. The major causes of death were hepatic neoplasms with matastases, although some early deaths occurred before neoplasms developed. Most deaths were from a malignant hemorrhagic liver tumor, histologically diagnosed as a hemangiosarcoma, which caused rupture and hemorrhage into the peritoneal cavity or metastases to the lungs. These hemangiosarcomas were readily transplantable and did not produce alpha-fetoprotein. Ultrastructurally, they were composed of poorly differentiated cells resembling endothelial cells. Nodules of hyperplasia induced by aflatoxin B1 sometimes grew large (greater than 1.5 cm), and 2 were transplanted. Approximately 20% of the rats had colon tumors; a few rats had tumors of the kidney, oral cavity, and hematopoietic system.

Aflatoxins↗

Application of a statistical dynamic model investigating the short-term cellular kinetics induced by riddelliine, a hepatic endothelial carcinogen.

In recent studies, riddelliine, a pyrrolizidine alkaloid, was found to increase rates of replication and apoptosis and induce hemangiosarcoma in the liver of rats and mice. To analyze DNA replication and apoptosis data taken from the same animals, we have developed a predictive mathematical model for describing BrdU labeling and apoptotic processes. The model allows the incorporation of simple diurnal patterns in cellular kinetics and is applied to data on hepatocytes and endothelial cells taken from riddelliine exposed rats. Predictions from the model were used with multivariable nonlinear regression techniques to estimate replication and apoptotic rate constants for both cell types and all treatment groups. Hypothesis tests were used with the predicted rates to separate the competing effects of riddelliine on replication and apoptosis of hepatocytes and endothelial cells as well as compare replication rates between cell types. That estimated replication rates were found to be significantly higher for endothelial cells supports the supposition of induction of hemangiosarcoma by riddelliine in the liver.

Algorithms↗