[Improvement of working conditions in lacquer-varnishing of interiors of railroad cars of metal construction].
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Amino Acyl-tRNA Synthetases↗
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Results for “LACQUER AND VARNISH”
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[Reaction of HeLa cells to the presence of the lacquer Evicrol Varnish].
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Composite Resins↗
[Occupational exposure to paint, lacquer and solvents, and cancer risk in the area of the upper aero-digestive tract].
So far, only few studies exist that have investigated the influence of occupational exposure to paint and lacquer on the risk of cancer in the upper aerodigestive tract. Based on data from the Heidelberg case control study which enrolled 369 patients with carcinomas of the upper aerodigestive tract and 1476 randomized control subjects, the relative risk of head and neck cancer in patients exposed to paint, lacquer and varnish was analyzed. The relative risk (RR) of squamous cell cancer (after adjustment for possible alcohol and tobacco effects) was significantly increased for the larynx (RR = 2.3) and the oral cavity (RR = 3.6). However, this risk was not increased for the pharynx. Our findings and a critical analysis of the literature provide evidence that chronic exposure to paint, varnish and lacquer is a definite risk factor for cancer of the upper aerodigestive tract. Further studies are required to confirm these findings, and to identify more precisely toxic substances encountered in the workplace.
Carcinoma, Squamous Cell↗
Using gas chromatography for indoor-air quality control in conservation and renovation studios.
Investigations were carried out in the Department of Conservation of Painting and Polychrome Sculpture and in the Screen Printing Studio of the Faculty of Art at Nicolaus Copernicus University. Concentration of the vapours of organic solvents was measured in 2 workshops: the Art Conservation Studio and the Screen Printing Studio. This study attempts to evaluate the work environment in both studios by analysing the concentration of vapour solvents over 5 to 7 years of measurements. Volatile solvents--aliphatic and aromatic hydrocarbons, alcohols, esters and ketones--were detected in investigated workplaces. These compounds have a wide range of applications in cleaning and removing old varnishes, lacquers and paints; inhalation is the main route of exposure. Vapour was collected using an active sampling method.
Air Pollution, Indoor↗
Epidemiology of laryngeal cancer: results of the Heidelberg case-control study.
Squamous cell carcinoma of the larynx is a multifactorial disease which predominantly is found in males aged 50-70 years. Chronic consumption of alcohol and tobacco independently increase the relative risk of this type of cancer in a dose-dependent manner. Low educational standards and occupational training are associated with high risk. The majority of the cancer patients are blue collar workers who are exposed to a variety of hazardous working materials like polycylic aromatic hydrocarbons, cement dust, metal dusts, asbestos, varnish, lacquer, etc. Environmental exposure to airborne carcinogens like fossil fuel single stove emissions may increase the relative risk of laryngeal cancer. The regular consumption of fruit, salad and dairy products which contain considerable amounts of tumor protective micronutrients may decrease the risk of laryngeal cancer.
Alcohol Drinking↗
Biotic and abiotic degradation behaviour of ethylene glycol monomethyl ether (EGME).
Glycol ethers are widely used in many processes in the chemical industry. Their high water solubility means they are used as solvents for different purposes (e.g. lacquers and varnishes). Since glycol ethers are known to produce toxic metabolites such as the teratogenic methoxyacetic acid during biodegradation, the biological treatment of glycol ethers can be hazardous. However, using oxidizing agents like hydrogen peroxide could be a feasible option for treating wastewater containing glycol ether. In this study, both-, biodegradation and abiotic oxidation experiments with ethylene glycol monomethyl ether (EGME) as contaminant were performed. The biodegradation experiments were conducted with a synthetic model wastewater containing 15 wt% NaCl and 5000 mgl(-1) of EGME. While experiments with the fungus Aspergillus versicolor resulted in the exhaustive biotic degradation of EGME, the toxic metabolite methoxyacetic acid (MAA) was produced as a 'dead end' product. Sodium hydroxide was added to adjust the decreasing pH caused by the production of MAA. In abiotic degradation experiments with EGME, other degradation products--organic acids and toxic aldehydes, e.g. methoxy acetaldehyde (MALD)--were detected. It must be taken into account that EGME and its biotic and abiotic degradation products are usually not analysed in routine wastewater measurements owing to their physical properties.
Acetaldehyde↗
[Cancer of the oral cavity in machine workers].
BACKGROUND: So far, only few studies exist which investigated the influence of occupational factors on the risk of oral cancer. PATIENTS: A case control study enrolling 100 patients with carcinomas of the oral cavity and 400 randomized control persons was performed to analyze occupational risk factors for oral cancer. RESULTS: Twenty-two percent of the tumor patients and only 8.5% of the control persons were employed as machine workers. The relative risk for squamous cell carcinoma of the oral cavity was 3.4 (K.I.: 1.7-7.0) for machine workers (adjusted for alcohol and tobacco). Single case analysis showed that 96.3% of the machine workers with oral cancer and only 17.3% of the machine workers in the control group were exposed to dust, especially metal dust (55.5% vs. 9.7%). Also the exposure to paint, lacquer, and varnish containing chromium and nickel was significantly higher in machine workers with cancer of the oral cavity than in the machine workers without cancer (29.6% vs. 10.9%). CONCLUSIONS: The findings suggest that exposition to various types of dust, especially metal dust, increases the risk of oral cancer in machine worker patients.
Adult↗
NTP technical report on the toxicity studies of Dibutyl Phthalate (CAS No. 84-74-2) Administered in Feed to F344/N Rats and B6C3F1 Mice.
Dibutyl phthalate is a phthalate ester with extensive use in industry in such products as plastic (PVC) piping, various varnishes and lacquers, safety glass, nail polishes, paper coatings, dental materials, pharmaceuticals, and plastic food wrap. Concomitant with this extensive worldwide use is the high potential for human exposure to dibutyl phthalate in the workplace and the home environment through direct sources as well as indirectly, through contamination of water, air, and foodstuffs. Because existing toxicity information was considered inadequate, the effects of exposure to dibutyl phthalate were examined in male and female F344/N rats and B6C3F1 mice in 13-week feed studies. Furthermore, due to concern over the potential for pervasive exposure of humans to dibutyl phthalate, additional perinatal studies examined rats and mice exposed as pups in utero, for the 4 weeks of lactation, and for an additional 4 weeks postweaning. Additional studies examined the effects on rats of combining perinatal and adult subchronic exposure. Due to the recognized biologic activity of this and other phthalates, hepatic peroxisome proliferation during the in utero and lactational phases and testicular toxicity during the perinatal period were also examined. Finally, reproductive assessment by continuous breeding (including crossover mating trials and offspring assessment) and genetic toxicity studies were also conducted. In the maximum perinatal exposure (MPE) determination study in rats, dibutyl phthalate was administered in the diet to dams during gestation and lactation, and to the pups postweaning for four additional weeks, at concentrations of 0, 1,250, 2,500, 5,000, 7,500, 10,000, and 20,000 ppm. Decreased weight gains were noted in dams exposed to 20,000 ppm during gestation and to dams exposed to 10,000 ppm during lactation. The gestation index (number of live pups per breeding female) was significantly lower in the 20,000 ppm group than in the controls, and pup mortality in this group was marked (100% by Day 1 of lactation); however, survival was 89% or greater in all other treatment groups. The mean body weight of pups in the 10,000 ppm group at Day 28 of lactation was approximately 90% of the mean weight of control pups. Pups were weaned onto diets containing dibutyl phthalate at the same concentrations fed to dams. After an additional 4 weeks of dietary administration, final mean body weights of pups in the 10,000 ppm groups were 92% of the control value for males and 95% of the control value for females. Hepatomegaly (increased relative liver weight) was observed in males in all exposed groups and in females receiving 2,500 ppm or greater. No gross lesions were observed at necropsy. Moderate hypospermia of the epididymis was diagnosed in all male rats in the 7,500 and 10,000 ppm groups; mild hypospermia of the epididymis was diagnosed in 2 of 10 males in the 5,000 ppm group. No degeneration of the germinal epithelium was detected in the testis of these rats. Thus, although toxicologically important, the epididymal hypospermia was not considered to be life threatening, and 10,000 ppm was recommended as the MPE concentration for male and female rats. In the subsequent subchronic toxicity study of dibutyl phthalate with perinatal exposure, dams were administered diets containing 0 or the MPE concentration (10,000 ppm) during gestation and lactation, and weaned pups were administered the same diets as their dams received for an additional 4 weeks, until the beginning of the 13-week exposure phase. Male and female rats then received diets containing dibutyl phthalate at concentrations of 0, 2,500, 5,000, 10,000, 20,000, and 40,000 ppm for 13 weeks. No mortality or toxicity was observed in dams during the perinatal phase of the study; however, before pups were culled at 4 days postpartum, the percentage of live pups per litter was 86% to 93% that of the controls. Through weaning, litter weights of exposed pups ranged from 89% to 92% of the control values. Ten control and ten exposed pups per sex were examined at the time of trol and ten exposed pups per sex were examined at the time of weaning; hepatomegaly and markedly increased peroxisomal enzyme activities (approximately 9-fold greater than the control values) were observed in exposed pups. Body weights of the perinatally exposed pups remained lower than those of the controls throughout the 4-week period before the 13-week adult exposures began. During the 13-week adult exposure phase, the final mean body weight of males in the MPE: 0 ppm control group (MPE rats, returned to the base diet for 13 weeks), was 95% that of the controls. The body weight gain of females in the MPE:0 ppm group was greater than that of the unexposed controls, and the final body weights of these two groups were similar. Body weight gains of rats treated with dibutyl phthalate as adults decreased with increasing exposure concentration; for rats that received the MPE concentration followed by 40,000 ppm for 13 weeks, final body weights were 51% of the control value for males and 74% of the control value for females. Hepatomegaly apparently regressed in rats in the MPE:0 ppm groups but was observed in male rats receiving 5,000 ppm or greater and in females receiving 2,500 ppm or greater. In males that received 20,000 ppm as adults, testis and epididymal weights were less than in the controls; males in the 40,000 ppm group also had a lower testis weight than the controls. Results of hematologic analyses conducted at the end of the 13-week exposure period suggested a mild anemia in male rats administered 10,000 ppm or greater as adults and female rats administered 40,000 ppm as adults. Hypocholesterolemia and hypotriglyceridemia were observed in male and female rats at the higher exposure concentrations. Hypotriglyceridemia was detected in females receiving 20,000 or 40,000 ppm and in males receiving 10,000 ppm or greater. Elevations in alkaline phosphatase activities and bile acid concentrations in male and female rats receiving 20,000 or 40,000 ppm as adults were indicative of cholestasis. Microscopic examination revealed hepatocellular cytoplasmic alteration, consistent with glycogen depletion, in male and female rats receiving a concentration of 10,000 ppm or greater. In the liver of rats receiving 40,000 ppm, small, fine, eosinophilic granules were also observed in the cytoplasm of hepatocytes. Ultrastructural examination suggested the presence of increased numbers of peroxisomes. Lipofuscin accumulation was detected in rats that received 10,000 ppm or greater. Consistent with the regression of the hepatomegaly in rats in the MPE:0 and MPE:2,500 ppm groups, peroxisomal enzyme activity was not elevated in these groups. Marked elevations of peroxisomal enzyme activity were detected, however, in males receiving 5,000 ppm or greater and in females receiving 10,000 ppm or greater; at the 40,000 ppm concentration, the highest concentration tested, enzyme activities were approximately 20 fold greater than the control values. Histopathologic examination of the testes revealed degeneration of the germinal epithelium, a mild to moderate focal lesion in rats in the 10,000 and 20,000 ppm groups and a marked, diffuse lesion in all males receiving 40,000 ppm; at 40,000 ppm, an almost complete loss of the germinal epithelium resulted. Testicular zinc concentrations were lower in the 40,000 ppm group than in the controls, a finding consistent with the marked loss of germinal epithelium at this exposure concentration. Spermatogenesis was evaluated in rats in the 0, 2,500, 10,000, and 20,000 ppm groups; rats administered 20,000 ppm had fewer spermatid heads per testis than the unexposed controls, and epididymal spermatozoal concentration was less than that in the MPE:0 ppm group. For comparison with the perinatal subchronic study, a standard 13-week evaluation of the toxicity of dibutyl phthalate in male and female rats was also conducted. In this study, rats received dibutyl phthalate at the same dietary concentrations used in the 13-week exposure phase of the study with perinatal exposure: 0, 2,500, 5,000, 10,000, 20,000, and 40,000 ppm. No deaths occurred in the standard study. Markedly reduced final mean body weights were observed in males and females in the 40,000 ppm groups (45% and 73% of control body weights, respectively); final mean body weights of males receiving 10,000 ppm or greater and females receiving 20,000 ppm or greater were lower than those of the controls. Hepatomegaly was observed in males that received 5,000 ppm or greater and in females that received 10,000 ppm or greater. Testis and epididymal weights of males in the 20,000 and 40,000 ppm groups were lower than those of the controls. A minimal anemia was detected in male rats receiving 5,000 ppm or greater. Hypocholesterolemia was observed in male and female rats receiving 20,000 or 40,000 ppm, and hypotriglyceridemia was detected in males in all exposed groups and in females receiving 10,000 ppm or greater. Elevations in alkaline phosphatase activity and bile acid concentration in male and female rats were considered indicative of cholestasis. Morphologic evaluation again confirmed the toxicity of dibutyl phthalate to the liver and testes of rats. Microscopic examination of the liver revealed hepatocellular cytoplasmic alterations, consistent with glycogen depletion, in male and female rats receiving 10,000 ppm or greater. In the liver of rats in the 40,000 ppm groups, small, fine, eosinophilic granules were also observed in the cytoplasm of hepatocytes. Ultrastructural examination suggested the presence of increased numbers of peroxisomes, and peroxisomal enzyme activity was elevated in the livers of male and female rats administered 5,000 ppm or greater; the enzyme activities in the 40,000 ppm groups were approximately 13-fold greater than the control value for males and 32-fold greater than the control value for females. Lipofuscin accumulation was detected in rats receiving 10,000 ppm or greater. Histopathologic examination of the testes revealed degeneration of the germinal epithelium, a mild to marked focal lesion in the 10,000 and 20,000 ppm groups and a marked, diffuse lesion in all males in the 40,000 ppm group; at 40,000 ppm, an almost complete loss of the germinal epithelium resulted. Testicular zinc concentrations were lower in the 20,000 and 40,000 ppm groups than in the controls. Serum testosterone values were also lower at these concentrations than in the controls. Spermatogenesis was evaluated in males in the 0, 2,500, 10,000, and 20,000 ppm groups; at 20,000 ppm, spermatid heads per testis and per gram testis, epididymal spermatozoal motility, and the number of epididymal spermatozoa per gram epididymis were lower than in the controls. All of these findings are consistent with the marked loss of germinal epithelium at these exposure concentrations. In the continuous breeding study, Sprague-Dawley rats received 0, 1,000, 5,000, or 10,000 ppm dibutyl phthalate in feed. Mean body weights of exposed dams at delivery and during lactation generally decreased with increasing exposure concentration. The mean pup weight at birth in the 10,000 ppm group was significantly lower than the control pup weight. The average number of live pups per litter in all exposed groups was lower than in the controls. Crossover mating trials in the F(0) generation revealed no effects on the fertility of male or female rats receiving 10,000 ppm. In contrast to the F(0) rats, mating, pregnancy, and fertility indices of F(1) rats were lower in the 10,000 ppm group than in the controls. Germinal epithelial degeneration of the testes and absence or under development of the epididymides were noted in F(1) males in the 10,000 ppm group. Interstitial cell hyperplasia was noted in 7 of 10 males in the 10,000 ppm group. These effects document the male and female reproductive toxicity of dibutyl phthalate in F(1) rats receiving 10,000 ppm and do not exclude the possibility of developmental toxicity to F2 offspring. In the MPE determination study in mice, dams received 0, 1,250, 2,500, 5,000, 7,500, 10,000, or 20,000 ppm dibutyl phthalate in feed during gestation and lactation; pups were weaned onto the same diets as the dams received and were exposed for an additional 4 weeks. The gestation period was longer in dams that received 2,500 ppm or greater than in the controls, and gestational body weight gain depressions were noted in dams receiving 7,500 ppm or greater. Only 5 of 20 females in the 10,000 ppm group delivered live pups, and none of the 20 females receiving 20,000 ppm delivered live pups. Only one pup in the 10,000 ppm group survived past Lactation Day 1; the number of live pups per litter in the 7,500 ppm group also remained low throughout lactation. No deaths of either male or female pups occurred after weaning. Initial (postweaning) and final body weights of male pups receiving 2,500 ppm or greater were significantly less than those of the control group. The mean body weights of exposed female pups were similar to the control body weight at weaning and remained similar throughout the 4 weeks postweaning. Hepatomegaly was present in male mice in all exposed groups, and the absolute liver weight of males administered 7,500 ppm was greater than that of the controls; although a similar change was apparent in females, no statistical differences between the liver weights of exposed and control females were detected. No treatment-related gross lesions were identified at necropsy, and no histopathologic lesions definitively associated with treatment were observed in male or female mice in the 7,500 ppm groups. The one surviving male pup in the 10,000 ppm group had cytoplasmic alteration in the liver, consistent with peroxisome proliferation. Developmental toxicity and fetal and pup mortality were suggested at concentrations as low as 7,500 ppm. No subchronic toxicity study with prior MPE exposure was conducted with mice, although an MPE concentration of 5,000 ppm was suggested by the data. In a standard 13-week toxicity study, mice received 0, 1,250, 2,500, 5,000, 10,000, or 20,000 ppm dibutyl phthalate in feed. No deaths occurred during this study. Mean body weights and weight gains of male and female mice decreased with increasing exposure concentration, and the decreases were significant for males and females that received 5,000 ppm or greater. Relative liver weights were greater in males and females receiving 5,000 ppm or greater than in the controls. A minimal anemia was suggested in female mice in the 20,000 ppm group. Although no gross lesions were observed at necropsy, microscopic examination revealed hepatocellular cytoplasmic alterations, consistent with glycogen depletion, in male mice receiving 10,000 or 20,000 ppm and female mice receiving 20,000 ppm. Small, fine, eosinophilic granules, consistent with peroxisome proliferation, were also observed in the cytoplasm of hepatocytes in males and females in the 20,000 ppm groups. Lipofuscin accumulation in the liver was detected in mice receiving 10,000 ppm or greater. In a continuous breeding study using Swiss (CD-1®) mice, animals received 0, 300, 3,000, or 10,000 ppm dibutyl phthalate in feed. The fertility index, average number of litters per breeding pair, and average number of live pups per litter in the 10,000 ppm group were lower than in the controls. Crossover mating trials of mice receiving 10,000 ppm revealed effects on dams in the F(0) generation, with a lower fertility index, number of live pups per litter, and pup weight than in the controls. Liver weights were greater in males and females, and the uterine weight was less in exposed dams than in the controls. No other changes were observed at necropsy or on histopathologic examination. These data document the female reproductive toxicity of dibutyl phthalate in F(0) mice. Dibutyl phthalate was not mutagenic in Salmonella typhimurium strain TA98, TA100, TA1535, or TA1537 with or without exogenous metabolic activation but did induce mutations in L5178Y mouse lymphoma cells treated without metabolic activation. In peripheral blood samples obtained from male and female mice at the end of the 13-week study, frequencies of micronucleated normochromatic erythrocytes were similar between exposed and control mice. Together, the studies in rodents suggest that young rodents (in utero and perinatal) respond in a manner qualitatively similar to that of adult rats and mice. Dibutyl phthalate induced toxic effects in rodents as pups in utero and during the lactational phases of development and also affected young adults, as evidenced by fetotoxicity and lethality, body weight gain decrements, increased liver weights, hepatic peroxisome proliferation, testicular toxicity, and female reproductive toxicity. Dibutyl phthalate was lethal to rat fetuses and rat and mouse neonates at dietary concentrations that were not toxic to dams. Otherwise, there was no teratogenic or morphologic evidence that rodent young were uniquely sensitive to the effects of short-term dibutyl phthalate treatment. Synonyms: 1,2-Benzenedicarboxylic acid dibutyl ester; benzene-o-dicarboxylic acid di-n-butyl ester; o-benzenedicarboxylic acid dibutyl ester; butyl phthalate; n-butyl phthalate; DBP; dibutyl 1,2-benzene dicarboxylate; dibutylphthalate; di-n-butylphthalate; di(n-butyl) phthalate; dibutyl-o-phthalate; phthalic acid dibutyl ester. Trade Names: Celluflex DBP; Elaol; Ergoplast FDB; Ersoplast FDA; Genoplast B; Hexaplas M/B; Palatinol C; Polycizer DBP; PX 104; RC Plasticizer DBP; Staflex DBP; Uniflex DBP; Unimoll DB; Witcizer 300; Witicizer 300. (NOTE: These studies were supported in part by funds from the Comprehensive Environmental Response, Compensation, and Liability Act trust fund (Superfund) by an interagency agreement with the Agency for Toxic Substances and Disease Registry, U.S. Public Health Service.)
Journal Article↗
NTP Toxicology and Carcinogenesis Studies 2-Butoxyethanol (CAS NO. 111-76-2) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).
2-Butoxyethanol is a member of a family of ethylene glycol monoalkyl ethers. It is used extensively as a solvent in surface coatings such as lacquers, enamels, varnishes, and latex paint; in paint thinners, paint stripping formulations, and inks; and in degreasers and industrial and household cleaners. 2-Butoxyethanol was nominated for study because of its widespread use in industrial and consumer applications, the potential for exposure to workers and the general population, and the absence of chronic toxicity data. Male and female F344/N rats and B6C3F1 mice were exposed to 2-butoxyethanol (greater than 99% pure) by inhalation (primary route of human exposure) for 14 weeks or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, and the bone marrow of male F344/N rats and B6C3F1 mice. 14-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were exposed to 2-butoxyethanol by inhalation at concentrations of 0, 31, 62.5, 125, 250, or 500 ppm, 6 hours per day, 5 days per week for 14 weeks. One female rat in the 250 ppm group was killed moribund during week 8; four females in the 500 ppm group were killed moribund during week 1 and one during week 5. Final mean body weights of females exposed to 500 ppm were significantly less than those of the chamber controls. Clinical findings included abnormal breathing, pallor, red urine stains, nasal and eye discharge, lethargy, and increased salivation and/or lacrimation. Due to vascular thrombosis and infarction in the tail vertebrae of 500 ppm female rats, the tails became necrotic and either sloughed off or were chewed off. The primary effect on the hematopoietic system was an anemia characterized as macrocytic, normochromic, and regenerative in males exposed to 125 ppm or greater and, to a greater extent, in all exposed groups of females. Compared to the chamber controls, kidney weights of males exposed to 500 ppm and females exposed to 125 ppm or greater and liver weights of males exposed to 250 or 500 ppm and females exposed to 125 ppm or greater were significantly increased, and thymus weights of females exposed to 500 ppm were significantly less. In female rats killed moribund, there was considerable histologic evidence of thrombosis in tissues and organs including the nasal cavity, incisors, liver, lung, and heart. In addition to thrombosis, infarction occurred in the vertebrae of the tail resulting in necrosis and loss of the distal portion of the tail. There were also inflammation, necrosis, and ulceration of the forestomach; necrosis and centrilobular degeneration of the liver; renal tubule degeneration; and atrophy of the spleen and thymus. Exposure-related increases in the incidences of Kupffer cell pigmentation, forestomach inflammation and epithelial hyperplasia, bone marrow hyperplasia, splenic hematopoietic cell proliferation, and renal tubule pigmentation were observed in male and/or female rats surviving to the end of the study. 14-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were exposed to 2-butoxyethanol by inhalation at concentrations of 0, 31, 62.5, 125, 250, or 500 ppm, 6 hours per day, 5 days per week for 14 weeks. Two male and two female mice exposed to 500 ppm died and two males and two females were killed moribund during the first 2 weeks of the study. Final mean body weights of 125, 250, and 500 ppm male mice were significantly less than those of the chamber controls. Clinical findings were observed only in 500 ppm males and females that died or were killed moribund and included abnormal breathing, red urine stains, and lethargy. Hematologic evaluation indicated an anemia that was characterized as normocytic, normochromic, and regenerative in mice exposed to 62.5 ppm or greater; the anemia was more pronounced in females. Liver weights of males exposed to 500 ppm were significantly greater than the chamber controls. In mice either dying early or killed moribund, there were inflammation, necrosis, and ulceration of the forestomach; mediastinal pleura and peritoneal inflammationmmation associated with the forestomach lesions; liver necrosis; renal tubule degeneration; atrophy of the spleen, thymus, and mandibular and mesenteric lymph nodes; and degeneration of the testis. Exposure-related increases in the incidences of hematopoietic cell proliferation and hemosiderin pigmentation of the spleen, Kupffer cell hemosiderin pigmentation of the liver, inflammation and epithelial hyperplasia of the forestomach, and renal tubule hemosiderin pigmentation occurred in male and/or female mice surviving to the end of the study. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were exposed to 2-butoxyethanol by inhalation at concentrations of 0, 31.2, 62.5, or 125 ppm, 6 hours per day, 5 days per week for 104 weeks. For hematology and bone marrow analyses, additional groups of 27 male and 27 female rats were exposed to 0, 62.5, or 125 ppm for evaluation at 3, 6, and 12 months and nine male and nine female rats were exposed to 31.2 ppm for evaluation at 3 (hematology only) and 6 months. Survival and Body Weights: Survival of exposed male and female rats was similar to the chamber control groups. The mean body weights of females exposed to 125 ppm were generally less than the chamber control group. Hematology and Bone Marrow Cellularity: The most consistent exposure-related effect on the hematopoietic system was an exposure concentration-related mild macrocytic, normochromic, regenerative anemia present at 3, 6, and 12 months, with females more affected than males. Significant increases in bone marrow cellularity and decreases in the myeloid/erythroid ratio relative to the chamber controls were observed at all time points in females exposed to 125 ppm, and a decrease in the myeloid/erythroid ratio was observed in males exposed to 125 ppm at 12 months. Pathology Findings: The incidence of benign or malignant pheochromocytoma (combined) of the adrenal medulla in females exposed to 125 ppm was not significantly increased compared to the chamber controls but exceeded the historical control range. Exposure-related increases in the incidences of hyaline degeneration of the olfactory epithelium and Kupffer cell pigmentation of the liver were observed in male and female rats. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female mice were exposed to 2-butoxyethanol by inhalation at concentrations of 0, 62.5, 125, or 250 ppm, 6 hours per day, 5 days per week for 104 weeks. For hematology and bone marrow analyses, additional groups of 30 male and 30 female mice were exposed to 0, 62.5, 125, or 250 ppm for evaluation at 3, 6, and 12 months. Survival and Body Weights: Survival of male mice exposed to 125 or 250 ppm was significantly less than that of the chamber control group. The mean body weights of exposed males were generally less than those of the chamber control group during the last 6 months of the study. The mean body weights of exposed female mice were less than those of the chamber control group; the reductions were greater and occurred earlier than those observed in males. Hematology: The most consistent exposure-related effect on the hematopoietic system was an exposure concentration-related minimal normocytic, normochromic, regenerative anemia present at 3, 6, and 12 months, with females affected slightly more than males. Pathology Findings: In females exposed to 250 ppm, incidences of forestomach squamous cell papilloma and squamous cell papilloma or carcinoma (combined) were significantly increased relative to the chamber controls, and these incidences exceeded the ranges in historical chamber controls. In 2-butoxyethanol exposed males, there were possible exposure-related increases in the incidences of squamous cell papilloma of the forestomach, although the increases were not significant and the incidences were within the historical control range for chamber controls. Accompanying these neoplasms in females and, to a lesser extent, in males were exposure-related increases in the incidences of ulcer and epithelial hyperplasia of the forestomach. In male mice exposed to 250 ppm, the incidence of hemangiosarcoma of the liver was significantly increased relative to chamber controls and exceeded the range in historical controls; in addition, there were possible exposure-related increases in the incidence of hepatocellular carcinoma. Incidences of hemosiderin pigmentation in the Kupffer cells were significantly increased in 125 and 250 ppm males and all exposed groups of females. The incidences of splenic hematopoietic cell proliferation and hemosiderin pigmentation were generally increased in males and females, and the incidences of bone marrow hyperplasia were increased in males. The incidences of hyaline degeneration of the olfactory and respiratory epithelia of the nose were increased in female mice. GENETIC TOXICOLOGY: 2-Butoxyethanol did not induce mutations in any of the S. typhimurium strains tested, with or without induced hamster or rat liver S9. 2-Butoxyethanol induced cycle delay but did not induce either sister chromatid exchanges or chromosomal aberrations in cultured Chinese hamster ovary cells with or without S9. 2-Butoxyethanol did not induce micronuclei in bone marrow cells of male rats or mice administered the chemical by intraperitoneal injection three times at 24-hour intervals. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was no evidence of carcinogenic activity of 2-butoxyethanol in male F344/N rats exposed to 31.2, 62.5, or 125 ppm. There was equivocal evidence of carcinogenic activity of 2-butoxyethanol in female F344/N rats based on the increased combined incidences of benign or malignant pheochromocytoma (mainly benign) of the adrenal medulla. There was some evidence of carcinogenic activity of 2-butoxyethanol in male B6C3F1 mice based on increased incidences of hemangiosarcoma of the liver. A marginal increase in the incidences of forestomach squamous cell papilloma and an increase in the incidences of hepatocellular carcinoma may have been exposure related. There was some evidence of carcinogenic activity of 2-butoxyethanol in female B6C3F1 mice based on increased incidences of fore stomach squamous cell papilloma or carcinoma (mainly papilloma). Increased incidences of forestomach neoplasms in male and female mice occurred in groups in which ulceration and hyperplasia were also present. Exposure to 2-butoxyethanol caused a mild regenerative anemia and effects secondary to the anemia. Synonyms: 2-Butoxy-1-ethanol; m-butyl ether; butyl glycol; ethylene glycol monobutyl ether Trade name: Butyl Cellosolve
Journal Article↗
NTP technical report on the toxicology and carcinogenesis studies of Stoddard Solvent IIC (Cas No. 64742-88-7) in F344/N rats and B6C3F1 mice (inhalation studies).
UNLABELLED: Stoddard solvent (white spirit/mineral spirit) is the most widely used solvent in the paint industry. It is used as a dry cleaning agent; as an extraction, cleaning, and degreasing solvent; and as a solvent in aerosols, paints, wood preservatives, asphalt products, lacquers, and varnishes. Stoddard solvent IIC was nominated by the International Union, United Auto Workers, for carcinogenicity testing because of the large volume used in industrial and other settings. Male and female F344/N rats and B6C3F1 mice were exposed to Stoddard solvent IIC (greater than 99% pure) by inhalation for 2 weeks, 3 months, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium and mouse peripheral blood erythrocytes. 2-WEEK STUDY IN RATS: Groups of five male and five female rats were exposed to Stoddard solvent IIC by inhalation at concentrations of 0, 138, 275, 550, 1,100, or 2,200 mg/m3, 6 hours per day, 5 days per week for 16 days. All rats survived to the end of the study, and mean body weights of all exposed groups were similar to those of the chamber controls. Liver weights of males exposed to 550 mg/m3 or greater and of females exposed to 275 mg/m3 or greater were increased. Minimal diffuse cytoplasmic vacuolization of hepatocytes of the liver occurred in all females exposed to 2,200 mg/m3. 2-WEEK STUDY IN MICE: Groups of five male and five female mice were exposed to Stoddard solvent IIC by inhalation at concentrations of 0, 138, 275, 550, 1,100, or 2,200 mg/m3, 6 hours per day, 5 days per week for 17 days. All mice survived to the end of the study, and mean body weights of all exposed groups were similar to those of the chamber controls. Liver weights of males and females exposed to 275 mg/m3 or greater were significantly increased. Cytomegaly of the liver occurred in all males and females exposed to 2,200 mg/m3. 3-MONTH STUDY IN RATS: Groups of 10 male and 10 female rats were exposed to Stoddard solvent IIC by inhalation at concentrations of 0, 138, 275, 550, 1,100, or 2,200 mg/m3, 6 hours per day, 5 days per week for 14 weeks. All rats survived to the end of the study, and the final mean body weight of females exposed to 275 mg/m3 was greater than that of the chamber controls. The relative kidney, liver, and testis weights of all exposed groups of males and the absolute kidney weights of males exposed to 550 mg/m3 or greater were increased. The sperm motility of 550 mg/m3 or greater males was significantly decreased. The incidences of renal tubule granular casts were significantly increased in males exposed to 550 mg/m3 or greater, and the severities of renal tubule hyaline droplet accumulation, granular casts, and regeneration increased with increasing exposure concentration in males. The incidences of goblet cell hypertrophy of the nasal respiratory epithelium in males and females exposed to 2,200 mg/m3 were significantly increased. Sperm motility was decreased in males exposed to 550 mg/m3 or greater. 3-MONTH STUDY IN MICE: Groups of 10 male and 10 female mice were exposed to Stoddard solvent IIC by inhalation at concentrations of 0, 138, 275, 550, 1,100, or 2,200 mg/m3, 6 hours per day, 5 days per week for 14 weeks. Mean body weights of exposed groups were similar to those of the chamber controls, but liver weights of males exposed to 2,200 mg/m3 were significantly increased. The sperm motility of 2,200 mg/m3 males was significantly decreased. This reduction in sperm motility, while statistically significant, is probably of modest importance as studies in mice have found that fertility is unaffected by motility decreases of less than 40%. The incidences of hematopoietic cell proliferation of the spleen in all exposed groups of females were greater than that in the chamber controls. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were exposed to Stoddard solvent IIC by inhalation at concentrations of 0, 138 (males), 550, 1,100, or 2,200 (females) mg/m3, 6 hours per day, 5 days per week for 104 to 105 weeks. Additional groups of 10 males and 10 females were exposed to the same concentrations for 3 months for renal toxicity analyses. Survival in the top exposure concentration groups of males and females was significantly less than that of the chamber controls. Mean body weights of exposed males and females were similar to those of the chamber controls. Cell proliferation analyses were performed in the left kidney of males and females after 3 months of exposure. The mean numbers of labeled cells and the labeling indices in males exposed to 550 and 1,100 mg/m3 were significantly increased. The amount of alpha2u-globulin in the right kidney of males increased with increasing exposure concentration. Also, the incidences of granular casts and cortical tubule degeneration and regeneration were generally increased in exposed males, as was the severity of hyaline droplets. These effects did not occur in females. At 2 years, the incidences of benign and benign or malignant pheochromocytoma (combined) of the adrenal medulla occurred with positive trends in males, and the incidences in the 550 and 1,100 mg/m3 groups were significantly increased. Due to increased incidences of renal tubule hyperplasia in males at 2 years, extended kidney evaluations were conducted; a slightly increased incidence of renal tubule adenoma occurred in the 1,100 mg/m3 group. Nonneoplastic lesions related to Stoddard solvent IIC exposure occurred in the kidney of males. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female mice were exposed to Stoddard solvent IIC by inhalation at concentrations of 0, 550, 1,100, or 2,200 mg/m3, 6 hours per day, 5 days per week for 105 weeks. Survival of exposed mice was similar to that of the chamber controls. Mean body weights of exposed females were greater than those of the chamber controls. The incidences of hepatocellular adenoma occurred with a positive trend in females, and the incidence of multiple hepatocellular adenoma in females exposed to 2,200 mg/m3 was significantly increased. However, the incidences of hepatocellular adenoma or carcinoma (combined) and hepatocellular carcinoma alone in exposed males and females were not significantly increased. GENETIC TOXICOLOGY: Stoddard solvent IIC was tested for mutagenicity in Salmonella typhimurium strains TA97, TA98, TA100, and TA1535, with and without S9 metabolic activation enzymes; all results were negative. In vivo, the frequency of micronucleated erythrocytes was assessed in peripheral blood samples from male and female B6C3F1 mice after 3 months of inhalation exposure to Stoddard solvent IIC, and results were negative. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was some evidence of carcinogenic activity of Stoddard solvent IIC in male F344/N rats based on increased incidences of adrenal medulla neoplasms; the slightly increased incidences of renal tubule adenoma may have been related to Stoddard solvent IIC exposure. There was no evidence of carcinogenic activity of Stoddard solvent IIC in female F344/N rats exposed to 550, 1,100, or 2,200 mg/m3. There was no evidence of carcinogenic activity of Stoddard solvent IIC in male B6C3F1 mice exposed to 550, 1,100, or 2,200 mg/m3. There was equivocal evidence of carcinogenic activity of Stoddard solvent IIC in female B6C3F1 mice based on increased incidences of hepatocellular adenoma; this slight increase was associated with increased body weight in exposed females. Exposure of male rats to Stoddard solvent IIC resulted in nonneoplastic lesions of the kidney characteristic of alpha2u-globulin accumulation.
Adrenal Gland Neoplasms↗
Ethoxyethanol behavioral teratology in rats.
2-ethoxyethanol, a solvent developed for nitrocellulose and also used in lacquers, dyes, varnish removers, and in numerous industrial processes, was evaluated for possible functional effects in offspring of rats exposed during gestation. A dose finding study revealed that no offspring survived inhalation exposure (7 hours/day) from gestation days 7-13 or 14-20 at 900 ppm, and there were approximately 34 percent neonatal deaths even after prenatal exposure to 200 ppm-the current Federal occupational standard. Consequently, pregnant Sprague-Dawley rats were exposed to 100 ppm ethoxyethanol for 7 hours/day on gestation days 7-13 or 14-20. The only effect observed in the mothers was slightly prolonged gestation in he mothers exposed on days 14-20 of gestation (p less than .001). Behavioral testing of offspring from dams exposed to ethoxyethanol on gestation days 7-13 revealed: (a) impaired performance on a rotorod test of neuromuscular ability (p = .002); (b) prolonged latency of leaving the start area of an open field (p = .009); and (c) marginal superiority in avoidance conditioning begun on day 34 of age (p = 061). Offspring from dams exposed to ethoxyethanol on gestation days 14-20: (a) were less active than controls in a running wheel (p = 0.32), and (b) received an increased number and duration of shocks in avoidance conditioning begun on day 60 of age (p = .004). Neurochemical evaluation of whole-brain samples from newborn pups revealed significantly decreased levels of norepinephrine in offspring from both exposure periods (p less than .01). In regional analyses of brains from 21-day-old offspring of dams exposed to 100 ppm ethoxyethanol on gestation days 7-13, the cerebrum had significant elevations in acetylcholine (p less than .01), norepinephrine ( p less than .01), and dopamine (p less than .05), the cerebellum had nearly a 3-fold increase in acetylcholine (p less than .01); the brainstem had an increase in norepinephrine (p less than 0.01); and the midbrain had excesses of acetylcholine (p less than .01), norepinephrine (p less than .05) and protein (p less than .05). In brains from 21-day-old offspring of dams exposed to ethoxyethanol on gestation days 14-20, the cerebrum had significant elevations in acetylcholine, dopamine, and 5-hydroxytryptamine (p less than .05). Overall, the results indicate that there are behavioral and neurochemical alterations in offspring of rats following prenatal exposure to 100 ppm ethoxyethanol.
Animals↗
The assessment of DNA damage in lymphocytes of wooden furniture workers.
Single-strand breaks (SSB) and DNA repair were detected in peripheral lymphocytes derived from workers of a furniture factory in a non-polluted region of Poland. The workers were exposed to wood dust (n = 19), or to the dust and varnishes or lacquers together (n = 5). Four groups were studied simultaneously: (a) exposed workers smokers of cigarettes (n = 14), (b) nonexposed smokers--control (n = 14), (c) exposed workers' nonsmokers (n = 14), (d) exposed nonsmokers (n = 10). In exposed workers DNA SSB and DNA repair were statistically significantly increased. DNA SSB was clearly higher in the smoking workers than in the smoking controls. Cigarette smoking itself has produced no evident increase in the frequency of DNA SSB in the control group. Occupational exposure had a significant effect on DNA repair in non stimulated lymphocytes both in smoking and nonsmoking workers.
DNA Damage↗
Airborne occupational exposure, ABO phenotype, and risk of obesity.
BACKGROUND: We have previously found a quite strong interplay between occupational airborne pollutants, ABO phenotypes, and risk of ischaemic heart disease (IHD), with long-term exposure being associated with a significantly increased risk among men with phenotype O, and not among men with other ABO phenotypes. We suggested that the biological pathway could be a stronger systemic inflammatory response in men with blood group O. Several inflammatory mediators likely to increase the risk of IHD have recently been linked also to obesity, suggesting that long-term exposure to airborne pollutants might play a role in the aetiology of obesity. Accordingly, we tested the hypothesis that long-term occupational exposure to airborne pollutants would be more strongly associated with obesity in men with phenotype O than in men with other ABO phenotypes. DESIGN: Cross-sectional exposure-response study taking into account potential confounders. SETTING: The Copenhagen Male Study. SUBJECTS: A total of 3290 men aged 53-74 y. MAIN OUTCOME MEASURE: Prevalence of obesity (BMI > or =30 (kg/m2)). RESULTS: Overall, no differences were found in the prevalence of obesity between men with the O phenotype (n=1399) and men with other phenotypes (n=1891), 8.6 and 9.0%. However, only among men with the O phenotype was long-term occupational exposure (at least 5 y of frequent exposure) to various respirable airborne pollutants: dust, asbestos, soldering fumes, welding fumes, organic solvents, fumes from lacquer, paint or varnish, toxic components, breath irritants, stench or strongly smelling products, and irritants (other than breath irritants or contagious components) associated with an increased prevalence of obesity. Statistically, the strongest univariate associations were found for asbestos exposure, welding fumes, and breath irritants. Odds ratios (95% confidence limits) for these factors were 3.7 (1.8-7.6), 2.7 (1.6-4.4), and 2.6 (1.5-4.4), respectively. This particular relationship of airborne exposures with obesity in men with phenotype O was supported in multivariate analysis including interaction terms and taking into account a number of potential confounders. In contrast, no gene-environment interactions with obesity were found with respect to ABO phenotypes and a number of nonrespirable exposures. CONCLUSION: The finding of a quite strong interplay between long-term exposure to airborne pollutants, ABO phenotypes, and risk of obesity may open up new possibilities for clarifying mechanisms underlying the global obesity epidemic.
ABO Blood-Group System↗
Histopathologic changes in dental and oral soft tissues in 2-butoxyethanol-induced hemolysis and thrombosis in rats*.
BACKGROUND: 2-Butoxyethanol (2-BE; ethylene glycol monobutyl ether) is extensively used as a solvent in surface coatings, such as lacquers, enamels, and varnishes in industrial and household cleaning products. Its major toxicity is manifested in the circulation, as it induces hemolytic anemia and thrombosis in various organs. While 2-BE has been implicated in the induction of anemia in different species, the rat has proven most sensitive, especially the female of this species. The purpose of this study was to document the effects of 2-BE on dentition, the periodontal ligament, the tongue, the salivary glands, and the oral mucosa in male and female Fischer 344 rats. METHODS: The experiment included 40 rats divided into five groups. Four groups were exposed to 2, 3, or 4 daily doses of 2-BE, and a fifth group served as control. The rats were killed on days 2, 3, 4, and 29. The teeth and soft oral tissues were prepared for histopathologic observation. RESULTS: The histopathologic analysis showed that the major effect of 2-BE was exerted on the odontoblasts of the incisors and on molars, with greater effect on the incisors. Foci of damaged muscle cells in the tongue were also observed. The blood vessels were dilated and congested, and a primary thrombosis was seen in the dental pulp. CONCLUSIONS: The results of this study revealed a resemblance between the dental injuries in this rat model and those seen in sickle cell anemia in humans. This 2-BE animal model holds potential to assist in the discovery of preventive measures and/or treatment for dental injuries that occur in human diseases with hemolytic anemia.
Anemia, Hemolytic↗
NTP Carcinogenesis Studies of Trichloroethylene (Without Epichlorohydrin) (CAS No. 79-01-6) in F344/N Rats and B6C3F1 Mice (Gavage Studies).
Trichloroethylene (TCE) is an industrial solvent used for vapor degreasing and cold cleaning of fabricated metal parts. TCE has also been used as a carrier solvent for the active ingredients of insecticides and fungicides, as a solvent for waxes, fats, resins, and oils, as an anesthetic for medical and dental use, and as an extractant for spice oleoresins and for caffeine from coffee. Trichloroethylene may be found in printing inks, varnishes, adhesives, paints, lacquers, spot removers, rug cleaners, disinfectants, and cosmetic cleansing fluids. TCE may also be used as a chain terminator in polyvinyl chloride production and as an intermediate in the production of pentachloroethane. Trichloroethylene is no longer used with food, drugs, or cosmetics. NTP Carcinogenesis studies of epichlorohydrin-free trichloroethylene were conducted by administering the test chemical in corn oil by gavage to groups of 50 male and 50 female F344/N rats and B6C3F1 mice. Dosage levels were 500 and 1,000 mg/kg for rats and 1,000 mg/kg for mice. Trichloroethylene was administered five times per week for 103 weeks, and surviving animals were killed between weeks 103 and 107. Groups of 50 rats and 50 mice of each sex received corn oil by gavage on the same schedule and served as vehicle controls. Groups of 50 male and 50 female rats were used as untreated controls. The dosage levels selected for the 2-year study were based on the results of the 13-week studies. Groups of 10 male and 10 female rats received TCE by gavage at doses of 125 to 2,000 mg/kg (males) and 62.5 to 1,000 mg/kg (females) for 13 weeks. Groups of 10 male and 10 female mice received gavage doses of 375 to 6,000 mg/kg of TCE for 13 weeks. Survival, body weight gains, and previous experience with TCE were used to select doses for the 2-year study. All rats survived the 13-week study, but males receiving 2,000 mg/kg exhibited a 24% difference in final body weight. At the 1,000 mg/kg dose, final body weights for males (-3%) and for females (-2%) were similar to those of controls. The doses selected for the 2-year study in rats were 500 and 1,000 mg/kg for both sexes. The initial doses used in the earlier bioassay in Osborne-Mendel rats were 549 and 1,097 mg/kg for both sexes. A total of 8/10 male mice and 10/10 female mice receiving doses of TCE as high as 1,500 mg/kg survived the 13-week experimental period. The single dosage level selected for the 2-year study in mice was 1,000 mg/kg for both sexes. This dose was less than the high dose used in the earlier bioassay in B6C3F1 mice (2,339 mg/kg for males and 1,739 for females) and was similar to the previous low doses (1,169 mg/kg for males and 869 for females). In the 2-year study, the survival of both low and high dose male rats and dosed male mice was less (P</=0.005) than that of the vehicle controls. Mean body weights of dosed rats of each sex were lower than those of the vehicle controls, and after week 65, the decrements in body weight gains were dose related. The mean body weight of dosed male mice was lower than that of the vehicle controls throughout the study, while those of the dosed and vehicle control female mice were comparable. Cytomegaly (toxic nephrosis) of the kidney was observed in 96/98 male and in 97/97 female rats given TCE, with none being found in male or female vehicle control rats. This lesion was more severe in males, particularly in the high dose group. Cytomegaly was observed in 45/50 male mice and in 48/49 female mice administered TCE, and in none of the vehicle controls. Renal tubular cell adenocarcinomas were found in the three high dose male rats; these neoplasms were observed in those male rats killed at the end of the study (0/33, 0/20, and 3/16, 19%). The incidence in the high dose male rats at the end of the study was greater (P<0.05) than that in the controls. Renal tubular cell adenocarcinomas are considered uncommon occurrences in F344/N rats, with 3/748 (0.4%) being observed in historical vehicle gavage controls. Additional renal tumors in dosed male rats included one transitional cell carcats included one transitional cell carcinoma of the renal pelvis and two tubular cell adenomas in low dose animals and one carcinoma of the renal pelvis in a high dose animal. No renal neoplasms were found in vehicle control rats; one untreated control male rat had a transitional cell papilloma of the renal pelvis. In female rats, one tubular cell adenocarcinoma was found in the high dose group. An increased incidence (P<0.05, life table) of peritoneal mesotheliomas was detected in low dose male rats (control, 1/50; low dose, 5/50; high dose, 1/49). Mesotheliomas have been diagnosed in 16/752 (2.1%) historical vehicle control male F344/N rats, and the increased incidence in the present study may have been related to the administration of TCE. The results in male F344/N rats were considered equivocal for detecting a carcinogenic response because both groups receiving TCE showed significantly reduced survival compared to vehicle controls (35/50, 70%, 20/50, 40%; 16/50, 32%) and because 20% of the animals in the high dose group were killed accidently by gavage error. Negative trends were observed for chromophobe adenomas of the pituitary gland and for endometrial stomal polyps in female rats. These decreases were not considered to be related to the administration of TCE. The administration of TCE to mice caused increased incidences of hepatocellular carcinoma in males (control, 8/48; dosed, 31/50; P<0.001) and in females (control, 2/48; dosed, 13/49; P<0.005). Hepatocellular carcinomas metastasized to the lungs in five dosed male mice and one control male mouse, and none were observed in females. The incidence of hepatocellular adenomas was increased in male mice (control, 7/48; dosed 14/50) and in female mice (control, 4/48; dosed, 16/49; P<0.05). Under the conditions of these studies, epichlorohydrin-free trichloroethylene caused renal tubular-cell neoplasms in male F344/N rats, produced toxic nephrosis in both sexes, and shortened the survival time of males. This experiment in male F344/N rats was considered to be inadequate to evaluate the presence or absence of a carcinogenic response to trichloroethylene. For female F344/N rats receiving trichloroethylene, containing no epichlorohydrin, there was no evidence of carcinogenicity. Trichloroethylene (without epichlorohydrin) was carcinogenic for B6C3F1 mice, causing increased incidences of hepatocellular carcinomas in males and females and of hepatocellular adenomas in females. Levels of Evidence of Carcinogenicity: Male Rats: Inadequate Study Female Rats: Negative Male Mice: Positive Female Mice: Positive Synonym: TCE
Journal Article↗
NTP toxicology and carcinogenesis studies of decalin (CAS No. 91-17-8) in F344/N rats and B6C3F(1) mice and a toxicology study of decalin in male NBR rats (inhalation studies).
Decalin is used as an industrial solvent for naphthalene, fats, resins, oils, and waxes. It is also used as a substitute for turpentine in lacquers, paints, and varnishes; as a solvent and stabilizer for shoe polishes and floor waxes; and as a constituent of motor fuels and lubricants. Other applications include use as a paint thinner and remover, a patent fuel in stoves, a high-density fuel in submarine-launched cruise missile systems, and in stain removal and cleaning machinery. Decalin was nominated for study by the National Cancer Institute because of its chemical structure, its potential for consumer exposure, and a lack of adequate testing of the chemical. Male and female F344/N rats and B6C3F(1) mice were exposed to decalin (greater than 99% pure) by inhalation for 2 weeks, 3 months, or 2 years. Groups of male NBR rats were exposed to decalin for 2 weeks. Male NBR rats do not produce alpha2u-globulin; the NBR rats were included to study the relationship of alpha2u-globulin and renal lesion induction. Genetic toxicology studies were conducted in Salmonella typhimurium and mouse peripheral blood erythrocytes. 2-WEEK STUDIES IN RATS: Groups of five male and five female F344/N rats and five male NBR rats were exposed to 0, 25, 50, 100, 200, or 400 ppm decalin vapor 6 hours per day, 5 days per week for 16 days. All rats survived to the end of the study, and mean body weights of exposed groups were similar to those of the chamber controls. Renal toxicity studies were performed in male F344/N and NBR rats. The numbers of labeled cells and the labeling indices in the left kidney of 200 and 400 ppm F344/N male rats were significantly greater than those in the chamber controls. The alpha2u-globulin/soluble protein ratios were significantly increased in all exposed groups of F344/N rats. Liver weights of male F344/N and NBR rats exposed to 100 ppm or greater were significantly increased, as were those of all exposed groups of females. Kidney weights of male F344/N rats exposed to 50 ppm or greater were significantly increased. Exposure-related hyaline droplet accumulation, degeneration and regeneration of renal cortical tubules, and granular casts occurred in the kidney of exposed F344/N male rats. 2-WEEK STUDIES IN MICE: Groups of five male and five female B6C3F(1) mice were exposed to 0, 25, 50, 100, 200, or 400 ppm decalin vapor 6 hours per day, 5 days per week for 17 days. All mice survived to the end of the study, and mean body weights of exposed groups were similar to those of the chamber control groups. Liver weights of 200 and 400 ppm males and females and 100 ppm females were significantly increased. 3-MONTH STUDY IN RATS: Groups of 25 male and 20 female F344/N rats were exposed to 0, 25, 50, 100, 200, or 400 ppm decalin vapor 6 hours per day, 5 days per week for 2 (five male renal toxicity rats), 6 (10 male and 10 female clinical pathology rats), or 14 (10 core study rats) weeks. All rats survived to the end of the study, and mean body weights of exposed groups were similar to those of the chamber control groups. Urinalysis results indicated that decalin exposure caused increases in urine glucose and protein concentrations and enzyme activities that were consistent with the renal lesions observed microscopically. Renal toxicity studies were performed on rats sacrificed at 2 and 6 weeks and at the end of the study. In kidney tissue examined for cell proliferation, the numbers of PCNA-labeled cells and labeling indices were generally significantly greater than those of the chamber controls in exposed groups of rats at all three time points. Concentrations of alpha2u-globulin in the kidney as well as the alpha2u-globulin/soluble protein ratios were significantly increased at week 2 in all exposed groups and in the 200 and 400 ppm groups at week 6 and at the end of the study. Absolute and/or relative kidney and liver weights of male rats exposed to 50 ppm or greater were increased. Incidences of renal tubule regeneration and granular casts in the medulla of the kidney in exposed male rats were increased, and the severities of hyaline droplets generally increased with increasing exposure concentration. 3-MONTH STUDY IN MICE: Groups of 10 male and 10 female B6C3F(1) mice were exposed to 0, 25, 50, 100, 200, or 400 ppm decalin vapor 6 hours per day, 5 days per week for 14 weeks. All mice survived to the end of the study, and mean body weights of exposed groups were similar to those of the chamber control groups. Liver weights of 200 and 400 ppm males and females were significantly increased. There was a significant exposure concentration-related decrease in the absolute spermatid head count and a significant decrease in absolute head count of the 400 ppm group compared to the chamber controls. Incidences of centrilobular cytomegaly of the liver were increased in exposed male mice. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female F344/N rats were exposed to 0, 25, 50 (male rats only), 100, or 400 ppm (female rats only) decalin vapor 6 hours per day, 5 days per week for 105 weeks. A group of 20 male rats was exposed to 400 ppm. Survival of exposed groups was similar to that of the chamber control groups. Mean body weights of 400 ppm males were slightly less than those of the chamber controls during the second year of the study. Incidences of renal tubule adenoma and adenoma or carcinoma (combined) and of benign or malignant pheochromocytoma (combined) of the adrenal medulla in 100 and 400 ppm males were significantly increased. There was a significant association between nephropathy severity and adrenal pheochromocytoma incidence. Nonneoplastic lesions related to decalin exposure occurred in the kidney of male rats. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female B6C3F(1) mice were exposed to 0, 25, 100, or 400 ppm decalin vapor 6 hours per day, 5 days per week for 105 weeks. Survival of exposed mice was similar to that of the chamber controls. Mean body weights of exposed groups were generally similar to those of the chamber control groups throughout the study. Increased incidences of hepatocellular neoplasms occurred in 25 and 400 ppm female mice, and the incidences of centrilobular hypertrophy, necrosis, syncytial alteration, and erythrophagocytosis of the liver in 400 ppm males were significantly increased. The incidences of uterine stromal polyp and stromal polyp or stromal sarcoma (combined) occurred with positive trends in female mice. PHARMACOKINETIC MODEL: The rate of metabolism of decalin was the same for males and females in rats and mice. Also in rats and mice, decalin metabolism was saturated at less than 400 ppm. Increased labeling indices in male rats were likely due to changes related to alpha2u-globulin. GENETIC TOXICOLOGY: Decalin was not mutagenic in S. typhimurium strains TA97, TA98, TA100, or TA1535, with or without induced hamster or rat liver S9 enzymes. A small but significant increase in the frequency of micronucleated normochromatic erythrocytes was noted in male mice exposed to decalin for 3 months; however, no induction of micronuclei was observed in female mice. CONCLUSIONS: Under the conditions of these studies, there was clear evidence of carcinogenic activity of decalin in male F344/N rats based on increased incidences of renal tubule neoplasms. The increased incidences of benign or malignant pheochromocytoma (combined) of the adrenal medulla in male rats were also considered to be exposure related. There was no evidence of carcinogenic activity of decalin in female F344/N rats exposed to 25, 100, or 400 ppm. There was no evidence of carcinogenic activity of decalin in male B6C3F(1) mice exposed to 25, 100, or 400 ppm. There was equivocal evidence of carcinogenic activity of decalin in female B6C3F(1) mice based on marginally increased incidences of hepatocellular and uterine neoplasms. Exposure of male rats to decalin resulted in nonneoplastic lesions of the kidney characteristic of alpha2u-globulin accumulation. Nonneoplastic lesions of the liver were observed in male mice exposed to decalin.
Administration, Inhalation↗
Drug delivery to the nail following topical application.
The absorption of drugs into the nail unit, following topical application to the nail plate, is highly desirable to treat nail disorders, such as onychomycosis (fungal infections of the nail). Nail permeability is however quite low and limits topical therapy to early/mild disease states. In this paper, the recent research into ungual drug delivery is reviewed. The nail unit and the two most common diseases affecting the nail--onychomycosis and nail psoriasis--are briefly described to set the scene and to give an overview of the nature and scope of the problem. The factors, which affect drug uptake and permeation through the nail plate such as solute molecular size, hydrophilicity/hydrophobicity, charge, and the nature of the vehicle, are then discussed, followed by ways of enhancing drug transport into and through the nail plate. Finally, drug-containing nail lacquers which, like cosmetic varnish, are brushed onto the nail plates to form a film, and from which drug is released and penetrates into the nail, are reviewed.
Administration, Topical↗
Dermatitis caused by Japanese Lacquer.
Explore the source record for details and available documents.
Dermatitis↗