Document KGr8o4n6rjOGoK0kY8KLb0Ov0

TOXICOLOGY AND APPLIED PHARMACOLOGY 71, 42-53 (1983) Protective Action of Diethyldithiocarbamate and Carbon Disulfide against Acute Toxicities Induced by 1,1-DlchloroethyIene in Mice Yasusuke Masuda1 and Nobue Nakayama Department of Toxicology, Niigata Coliege Pharmacy, Niigata 950-21, Japan Received January 25, 1983; accepted June l, 1983 Protective Action of Diethyktithiocarbamate and Carbon Disulfide against Acute Toxicities Induced by 1,1 -Diehloroethyiene in Mice. Masuda, Y., and Nakayama, N. (1983). Toxicol. Appl. Pharmacol. 71, 42-53. In male mice of ddY strain, a single dose of 1,1-dichloroelhylene (1,1-DCE, 0.1 ral/kg, ip) produced severe renal damage at 24 hr, as evidenced by elevations in plasma urea nitrogen concentration and kidney calcium content and by massive renal tubular necrosis, while hepatic damage was less severe. A precipitous decrease in body temperature started as early as 30 min after administration of 1,1-DCE and lasted for 24 hr. Glutathione concentrations dnrerad in the liver and kidney, with a rebound increase seen in the former but not in the latter tissue. In carbon tetrachloride-poisoned mice, the renal toxicity of 1,1-DCE was markedly, potentiated. Prctreatment with either diethyldithiocarbamate (DTC) or carbon disulfide (CSj) blocked all of these l,1-DCE-induced toxic manifestations in normal and carbon tetrachloridepoisoned mice. Both agents, however, did not prevent the hypothermia induced by mooochloroacetic acid or chlonwcetyl chloride, proposed active metabolites of 1,1-DCE. Since DTC and CSj inhibited hepatic and renal microsomal drug metabolizing enzyme activities (Masuda and Nakayama, 1982, 1983), h is probable that the protective action of DTC and CSj against renal and hepatic injury induced by 1,1-DCE may be due to an inhibition ofthe metabolic activation of 1,1 -DCE to its proposed epoxide in each organ. The action ofDTC given po may be mediated by CS2 produced in the stomach. The hypothermia induced by 1,1-DCE may not result from a direct action of 1,1-DCE per se, but by its metabolites. As previously reported (Masuda and Na kayama, 1982), diethyldithiocarbamate (DTC) and carbon disulfide (CS3) protected mice against liver injury induced by various hepatotoxins such as carbon tetrachloride, chloroform, bromotrichloromethane, thioacetamide, furosemide, acetaminophen, bromobenzene, dimethylnitrosamirie, and tri chloroethylene, all ofwhich require metabolic activation by the microsomal monooxygenase system. DTC and CS3 also prevented chlo roform-induced renal injury in mice (Masuda and Nakayama, 1983). Since both agents in hibited microsomal drug metabolizing enzyme - * To whom correspondence should be addressed. activity in the liver and kidney in these studies, we suggested that the protective action might be due to an inhibition of bioactivation of these hepato- and nephrotoxins. It was also proposed that the protective action of DTC may be mediated through CS2 particularly when administered po. Thus, as an extension of these studies, we examined the possible protective effects of these agents against 1,1dichloroethylene (1,1-DCE), another hepatic and renal toxicant that requires bioactivation by the microsomal monooxygenase system (Bonse el al. 1975; Bartsch et al. 1975; Leibman and Ortiz, 1977; Jones and Hathway, 1978; Andersen et al,, 1980). A protective action ofDTC against the hepatotoxicity of 1,1-DCE in rats was reported 0041-008X/83 $3.00 Copyright C 1913 by Acpdcmk Nu. tar. AH ri*hu oT reproduction ia any Ibrai marred. 42 by Sieg the ant from in! DCE, sin DCE in v Althou rats has t regarding 1967;Jer al. (1977) than rats rotoxic ef exposure, thiram, 1 toxicity. 1 anism, h an attem; tective nv was exan content v action ag CCU-poi: cz Tr--O Chemicc were as foil NJ Kogyo Co. O N5 Protec T Control (i; 1,1-DCE (( DTC (30 n DTC (100 CSj (10 CSj (30 mi DTC 0 Each value `Signifit * Signific -\ TOXICOLOGY AND APPLIED PHARMACOLOGY 68, I40-1SI (1983) ctJUl^Lf The Uptake and Disposition of 1,1-Dichloroethyiene in Rats during inhalation Exposure1*2 C. E. Dallas,* F. W. Weir,* S. Feldman,! L. Putcha4 and J. V. Bruckner^3 Environmental Science Discipline, The University of Texas School ofPublic Health. Houston, Texas; tDepartment ofPharmaceutics, University ofHouston, College ofPharmacy, Houston, Texas; and ^Division of Toxicology, Department ofPharmacology. The University of Texas Medical School. Houston, Texas 7702S Received October 2,1982; accepted November 24, 1982 The Uptake and Disposition of I, I-Dichloroethylene in Rats during Inhalation Exposure. Dallas, C. E., Weir, F. W., Feldman, S., Putcha, L., and Bruckner, Jr V. (1983). Toxicol. Appt. Pharmacol. 68, 140-151. The uptake, disposition, and respiratory elimination or 1,1dichloroethylene (1,1-DCE) during inhalation exposure were evaluated to gain insight into the pharmacodynamics of the halocarbon. Anesthetized male Sprague-Dawley rats inhaled 25,75, 150, oi 300 ppm 1,1-DCE (or 3 hr from an aluminized Mylar bag through a miniaturized one way breathing valve inserted into the trachea. Periodic air samples were taken immediately adjacent to the valve from the separate inhaled air and exhaled breath streams concurrently with blood samples from a cannutaied femoral vein and analyzed for 1,1-DCE content by gas chro matography. 1,1-DCE was absorbed very rapidly, in that substantial levels were present in the venous blood at the first sampling time <i.e.. 2 min). Percentage systemic uptake decreased over time after initiation ofexposure until equilibrium was established. Percentage uptake after reach ing equilibrium varied inversely with the exposure concentration. 1,1-DCE venous whole-blood levels in animals exposed to 25,75, and 150 ppm 1,1-DCE increased rapidly to near steady state within approximately 45 min, as did concentrations of 1,1-DCE in the exhaled breath and alveolar air. Calculation of the amount of 1,1-DCE taken up by the body over the course of the 3-hr exposures revealed that cumulative uptake of the inhaled chemical was statistically linear for the 25-, 75-, and ISO-ppm exposures. Accumulation plots for 300-ppm exposed animals, how ever, were best fitted to a cubic curve form. Although trends toward the establishment of equi librium were initially seen in the 300-ppm exposed animals, levels of 1,1-DCE in the blood and breath rose progressively during the latter hour of the 3-hr exposure period. Thus, despite in creased exhalation of 1,1-DCE, these animals could not prevent systemic accumulation of the chemical. I,t-Dichloroelhylene (1,1-DCE), also known as vinylidene chloride, is used widely as a monomer in the manufacture of a variety of plastic materials. In addition to the potential for exposure in the occupational environ ment, 1,1-DCE and other halocarbons are contaminants of drinking water supplies (U.S. EPA, 1975, 1977). 1 Presented in part at the annual meeting ofthe Society ofToxicology in Boston, Mass., February 1982. 1 Supported by U.S. EPA Grunt K808282 and NIEIIS Training Grant ES07090. } To whom reprint requests should be seal. The pharmacokinetics and metabolic fate of 1,1-DCE are of considerable interest, in that both toxicity (Andersen and Jenkins, 1977; Andersen et at., 1979a) and carcino genicity (Maltoni et al., 1977) are highly dose dependent. Maltoni etal. (1977), for example, saw no increase over controls in tumor inci dence in male mice exposed to 10 ppm of 1,1-DCE vapor, but a significant incidence in 2S-ppm exposed animals. McKenna el al. (1978a) reported that rals subjected to 10 ppm 1,1-DCE for 6 hr were capable of metaboliz ing about 98% of the systemically absorbed 0041-Q08X/83 S3.00 Copyritht C 19*1 by Academic Prcu. Inc. AD njhu of icpraducuon in any form icmrved. 140 .V ' . URL 20122 ..V" w V0- Chemkal CAS No. NTP No. NTP Report No. TR Report No. Peer Review Date Use Tftble 1. (continued) , Route/dose Testing laboratory NTP chemical Results under the conditions manager of these teats*-1 VInylkJene chloride (1,1-dichJoroethylene) 75-35-4 10109-A NTP-80-082 TR-228 02/18/81 Intermediate forl.M-trichloroethane, monomer for vinyUdene copolymers Gavage, 5 times/week: rats, 1 or 5 mg/kg; mice, 2 or 10 mg/kg Gulf South Research Institute Dr. R. S. Chhabra Not carcinogenic for F344 rats or B6C3Fi mice of either sex (increased incidence of liver necrosis in male mice 1/46, 3/46, 7/49*). Zearalenone 17924-92-4 10770-C NTP-81-054 TR-235 12/16/81 Nonsteroid estrogenic mycotoxin (anabolic steroid) Feed: rata, 25 or 50 ppm; mice, 50 or 100 ppm Southern Research Institute Dr. D. Goldman Not carcinogenic for F344 rats ofcither sex; should be considered carcinogenic for B6C3F} mice (male: pituitary adenoma 0/40, 4/45, 6/44*; female: pituitary adenoma 3/46,2/43,13/42*; hepatocellular adenoma 0/50, 2/49, 7/49*). Zinm (Zinc dimetbylditluo* carbamate) 137-3-4 10690-G NTP-81-067 TR-238 12/16/81 Fungicide and accelerator in rubber vulcanization Feed: rata, 300 or 600 ppm; mice, 600 or 1200 ppm Southern Research Institute Dr. D. Goldman Carcinogenic for male F344 rats causing C-cell carcinomas of the thyroid 0/50, 2/49, 7/49*; not carcinogenic for female F344 rata or far nude B6C3Fj mice; interpretation of the increased number of female B6C3Fj mice with alveolar/ bronchiolar adenoma (2/50, 5/49, 1(V50*) is com plicated because of a concomitant Sendai viral infection (in all groups of mice). P - published. Ineidence results are ordered by concurrent controls, low dose, and high doae groups, with the numerator being the number of tumor (or noneoplastic lesion) bearing animals and the denominator the immfrer of niTMi examined. ** " statistically significant, p<0.06. 3 E1H '3 T b*k &a*g.g.? fSfa&ilsjr AC* Oncology 37; 136-141 (1980) cJLltuJlj Long-Term Testing of Vinylidene Chloride and Chloroprene for Carcinogenicity in Rats V. Ponomarkov and L. Tomatis Unit of Chemical Carcinogenesis, international Agency for Research on Cancer, Lyon Key Words. Vinylidene chloride Chloroprene Acute toxicity Carcinogenicity in rats Abstract Vinylidene chloride (VDC) monomer dissolved in olive oil was given orally to female BD IV rats (150 mg/kg body weight) on the 37th day of gestation. Their offspring were treated weekly with 50 mg/kg body weight VDC by stomach tube from the time of weaning for life span. Liver and meningeal tumours were more frequently observed in treated than in untreated animals, but the total number of tumour-bearing animals was not significantly different between treated and untreated animals. Chloroprene (CP) monomer dissolved in olive oil was given orally to female BD IV rats (100 mg/kg body weight) on the 17th day of gestation and their offspring were treated weekly with 50 mg/kg body weight by stomach tube from the time of weaning for life span. Total incidence of tumours was similar in treated and untreated animals. The data presented provide limited evidence of the carcinogenicity of VDC and no evidence of the carcinogenicity of CP when given by the oral route to rats. Introduction Vinylidene chloride (VDC), a chemical structurally related to vinyl chloride, is widely used in the manu facture of plastics, with a world production which prob ably was in excess of 150,000 t in 1976. In spite of its widespread production and use, relatively few (mostly inconclusive) studies are available on its possible acute and long-term effects in humans. One report on the long-term effects of VDC, involving 138 workers, in dicated no statistically significant effects related to VDC exposure [1] but the number of individuals lost to fol low-up in this study was high and the period of obser vation relatively short. In a preliminary mortality study on 629 workers from a VDC production and poly merization plant, where exposure to vinyl chloride and acrylonitrile also occurred, 7 of the 35 deaths reported were from malignant tumours, which was not greater than the expected value. Two bronchial carcinomas occurred in persons aged 35-39 whereas 0.08 were expected. However, no information was given on smok ing habits [2; see also 15]. Experimentally, VDC has been shown to have a low toxicity in rats [3]. The results of a number of longterm carcinogenicity tests have recently become available, either as preliminary communications or as interim results of on-going studies [4-6). The preliminary re sults of one study, in which VDC was given by inhala tion, point to the induction of kidney carcinoma in mice and to an increased incidence of mammary tumours in rats, no carcinogenic effect was observed when VDC was administered by the oral route to rats or hamsters [4]. An increased incidence of lung, skin and liver cell tumours in mice and the induction of haemangiosarcomas in both mice and rats was reported in another inhalation study [7]. In addition, VDC has been shown to be mutagenic to Salmonella typhimurium (8). Chloroprene (CP) is used as a chemical intermediate, mainly as the monomer in the manufacture of synthetic elastomers. World production of this compound in 1977 is estimated to have been 300,0001. Acute toxic effects in humans exposed to CP were reported to be depression of the central nervous system, various lesions of the lung, kidney and liver, hair loss C TO o ^ * .<* ,* H V':. V.-J A Carcinogenicity Test of Vinylidene Chloride and Chloroprene in Rats % 137 and irritation of skin and eyes [9]. The results of long term studies of workers occupationally exposed to CP are contradictory. In one investigation, in which several inadequacies have been recognized (i.e. failure to dis tinguish prevalent from incident cases, no adjustment for effect of age and sex, no measure of the extent of exposure), excesses of lung and skin cancer were re ported [10, 11]. In another study, which also had limi tations (among which were no data on potentially con founding variables, incomplete follow-up and small number of persons/years of exposure) no excess rates of lung and skin cancer were reported in two cohorts of males engaged in the production of CP [12; see also 15). Cytogenetic effects on human lymphocytes have been reported [13]. CP has been tested for carcinogenicity in rats by oral, subcutaneous and intratracheal administration and in mice by skin application [14]. No carcinogenic effect was detected in these studies. However, CP has been found to be mutagenic in 5. typhimurium [8]. A comprehensive review of the data on VDC and CP is available [IS]. We report here the results of a long-term carcino genicity test in which VDC and CP were given by the oral route to rats. was available ad libitum. Samples of feed were analysed twice during the course of the experiments for the presence of nitrosamines (the analysis was carried out by Dr. Prtussmann of the `Deutsches Krebs* forschungszentrum*. whose collaboration is gratefully acknowledged): dimethylnitrosamine and diethylnitrosamine were present at levels of 0.2--0.6 ppb. VDC (purity 99%, containing 0.03% 4-methoxyphenol) obtained from Merck-Schuchardt, Darmstadt. FRG, and CP (purity 99%, con taining 0.8% 1-chlorobutadiene), provided by Distugil, Le-Pont-deClaix, France, were dissolved in olive oil and administered to the animab by stomach tube. The same schedule of treatment was chosen for both experiments: single ora! administration of the chem ical to females on the 17th day of gestation and continuous weekly ora! treatment of their offspring from time of weaning for life span. 24 female BDIV rats were given a single dose of ISO mg/kg body weight VDC in olive oil by stomach tube on the 17th day of pregnancy, and their progeny (89 males and 90 females) received weekly doses of 50 mg/kg body weight VDC in 0.3 ml olive oil. 17 female BDIV rats were administered a single oral dose of 100 mg/kg body weight CP in olive oil on the 17th day of pregnancy, and their progeny (81 males and 64 females) were treated weekly with 50 mg/kg body weight CP in 0.3 ml olive oil. Controls for experiments with both VDC and CP were 14 female BD IV rats which received 0.3 ml olive oil on the 17th day of preg nancy and their progeny (53 males and 53 females), which were given 0.3 ml olive oil weekly for life beginning at weaning. AH survivors were killed at 120 weeks or when moribund. All animab were autopsied and major internal organs as well as those that showed gross abnormalities were examined histologically. Sec tions were routinely stained with haematoxylin-eosin; special stains were used when necessary. Materials and Methods Results Inbred BDIV rats, originally provided by Prof. H. Druckrey (Freiburg, FRG), were used in these experiments. The animals were kept in Makrolon Nil! cages under normal laboratory conditions and were maintained on Charles River food pellets until January 1976 and then on Aliment Extralabo Biscuits (Pietrement). Water Vinylidene Chloride The single oral LDSn level of VDC for the animals used in the experiment was established by giving groups of four rats single oral doses of VDC in olive oil and URL 20)25 Table I. Survival rates of BDIV rats treated with VDC and of controls Croup Females given VDC Progeny treated weekly with VDC Males Females Females given olive oil Progeny treated weekly with olive oil Males Females Initial number of animab 24 .Number of survivors according to duration of treatment (weeks) --. 10 20 30 40 50 60 70 80 90 100 110 120 24 24 24 24 24 24 24 23 23 22 19 14 89 85 85 82 ` 81 80 78 76 75 71 65 54 41 90 86 85 83 8! 81 80 80 79 75 72 61 56 14 14 14 14 14 14 14 14 14 14 12 11 11 * 53 53 53 53 53 53 53 52 52 49 44 41 27 53 52 52 52 52 52 51 50 49 47 40 34 26 138 Ponomarkov/Tomatis Table II. Tumour incidence in female BDIV rats treated with VDC on day 17 of pregnancy, in their progeny treated weekly for life and in controls Croup Effective number of rats' Tumourbearing rats Number of tumours Animals with more than one tumour Distribution of tumours meninges oral cavity stomach Females given VDC Progeny treated weekly with VDC Males Females Females given olive oil Progeny treated weekly with olive oil Maks Females 23 81 80 14 49 47 n% 1) 47.8. 31 38.3 53 66.3 5 357 16 32.7 24 51.1 total per rat 14 0.6 35 0.4 64 0.8 7 0.5 16 0.3 29 0.6 n% 3 13 4 4.9 11 13.8 2 14.3 _ 5 10.6 n% n% n% __ 2 8.7 1 4.3 6 7.4 __ __ 5 6.2 1 1.3 1 7.1 1 1.2 2 2.5 __ 1 2.0 -- 2 4.1 1 2.1 __ 1 2.1 The percentages and the number of tumours per rat are expressed in relation to the effective number of rats. * Survivors at the time the first tumours were observed. 3 Urinary bladder papilloma. * 1 lymphoma, 4 pituitary adenomas; 3 adrenal cortical adenomas; 1 spleen haemangioma; 1 lung sarcoma, pleomorphic; 1 skin squamous cell carcinoma; 1 seminoma. 4 1 salivary gland carcinoma; 1 salivary gland adenoma; ! lymphoma; 1 pituitary adenoma; 1 rectal adenomatous polyp; 1 uterine adenoma. * Adrenal cortical adenoma. * 1 osteosarcoma; 1 mediastinal sarcoma; 1 lung epidermoid carcinoma; 2 lymphomas; 1 spleen haemangioma; 2 pituitary adenomas; 1 adrenal cortical adenoma. ' 1 lymphoma; 1 uterine adenoma. ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------; e Table 111. Survival rates of CP-treated BD1V rats and controls Croup Initial number of animals Number of survivors according to duration of treatment (weeks) - -- . --- 10 20 30 40 50 60 70 80 90 100 no 120 Females given CP Progeny treated weekly with CP Males Females Females given olive oil Progeny treated weekly with olive oil Males Females 17 81 64 14 53 53 17 17 17 17 17 17 17 16 16 15 15 13 77 76 70 66 66 66 66 66 64 60 48 40 64 63 63 62 61 61 61 59 57 56 51 43 14 14 14 14 14 14 14 14 14 12 11 11 53 53 53 - 53 53 53 52 52 49 44 41 27 52 52 52 52 S2 SI 50 49 47 40 34 26 - ro o was calculated following the method described by Weil [16]; it was 1,800 mg/kg body weight for males and 1,500 mg/kg body weight for females. Litter sizes and pre-weaning mortality were similar in VDC-treated and control groups (5%). Survival rates, summarized in table I, were similar in the two groups; and there was no difference in body weights between VDC and control animals. .>?> . K. v'. * ' C i`K T Carcinogenicity Test of Vinylidene Chloride and Chloroprene in Rats V 139 liver n% soft tissue n% mammary ovary gland n% n% other Liver hyperpt. nodules n% n% -- -- 8 34.8 2 8.7 l2 4J 2 8.7 1 1.2 3 3.8 9 11.1 1 1.2 7 8.8 39 48.8 6 7.5 1 7.1 4 28.6 12s 14.8 2 2.5 64 7.5 6 7.5 l5 7.1 notably, one squamous-cell carcinoma of the stomach, one liver cell cardnoma, one seminoma and one rectal adenomatous polyp. Meningiomas were also more fre quent in VDC-treated males than in controls (6/81 vs. 1/49), but the difference was not significant (p = 0.37). In VDC-treated females, two liver cell carcino mas, one liver cell adenoma and one carcinoma and one adenoma of the salivary gland were observed, which were not seen among controls. Additionally, hyperplastic liver nodules were found in 2/23 females given a single VDC administration during pregnancy, and 2/81 males and 6/80 females among their progeny: no hyperplastic nodules were found in vehicle-treated controls. TTiis difference was significant (p = 0.04). -- 4 8.2 -- 22 46.8 3 6.4 9` 18,4' 2' 4.3 - - In rats weekly treated with VDC that died up to 30 weeks after the start of treatment, a pronounced congestion of lungs and kidney was detected. Later, at up to 80-90 weeks, haemorrhages and multiple lobular necrosis of the liver were observed. The animals which died after 90 weeks and some survivors killed at the age of 120 weeks, showed degenerative lesions of liver parenchymal cells, consisting of large, balloon cells with dear cytoplasm, often nodular with a distinct border towards normal parenchyma. No excessive stor age of glycogen was detected by the appropriate histochemical method. Tumours: data on tumour incidence are summarized in table II. There were minor differences in the per centages of tumour-bearing animals among VDC- and vehicle-treated animals, but these were not statistically significant. A few tumours were observed among VDC-treated males that were not seen in vehicle-treated controls, Chloroprene The oral LD50 of chloroprene in adult BDIV rats was determined as 900 mg/kg body weight. Litter sizes and pre-weaning mortality were not different in CPtreated animals from those in controls. Survival rates, summarized in table III, were similar in both treated and control groups of animals; and there was no dif ference in the body weights of CP-treated and control animals. Animals treated weekly with CP that died within the first 23-35 weeks after the beginning of the treatment, showed severe congestion of lungs and kidneys. In some animals autopsied 80-90 weeks after the start of the treatment, multiple liver necroses were observed. Tumours: data on tumour incidence are given in table IV. Although several tumours that were observed in males treated weekly with CP were not seen in vehicle-treated controls, and although subcutaneous fibromas were more numerous in CP-treated males than in controls, the total incidence of tumours was similar in CP-treated and control rats. Discussion The oral administration of VDC to rats did not pro duce a statistically significant increase in the total num ber of tumour-bearing animals, although an increased incidence of tumours at certain sites was observed. In particular, the incidence of liver tumours was increased in rats of both sexes and that of meningiomas in males. In addition, hyperplastic nodules of the liver were ob served in both male and female rats; these were not seen in controls. VDC was given to rats at a dose level which did not URL 2012? 1\ ? [ it ji -i it .*. i ;l J 140 Ponomarkov/Tomatis Table IV. Tumour incidence in female BD IV rats treated with CP on day 17 of pregnancy, in their progeny treated weekly tor life and in controls Group Effective number of rats1 Tumourbearing rats Number of . tumours Animals with more than one tumour Distribution of tumours oral cavity mammary gland Females given CP Progeny treated weekly with CP Males Females Females given olive oil Progeny treated weekly with olive oil Males Females 16 54 62 14 49 47 n% 9 562 15 27.8 33 53.2 5 35.7 16 32.7 24 Sl.l total 14 per rat 0.9 n 5 18 0.3 37 0.6 7 0.5 3 4 2 16 0.3 29 0.6 -- 5 % 31.3 5.6 6.5 14.3 _ 10.6 n %n % 1 6.3 6 37.5 __ __ --- 25 40.3 1 7.1 4 28.6 2 4.1 - - 1 2.1 22 46.8 The percentages and the number of tumours per rat are expressed in relation to the effective number of rats. 1 Survivors at the lime the first tumours were observed. 2 1 uterine squamous cell carcinoma; 1 lung reticuiosarcoma; 1 forestomacb papilloma; 1 sebaceous basal cell carcinoma. 2 1 intestinal leiomyosarcoma; 1 osteoma; 1 kidney mesenchymal tumour; 1 bone haemangioma; 1 neurinoma of the optic nerve; 1 adrenal cortical adenoma; 1 transitional-cell carcinoma of urinary bladder; 1 forestomach papilloma. * Adrenal cortical adenoma. * 2 lymphomas; 1 Lung epidermoid carcinoma; 1 spleen haemangioma; 1 osteosarcoma; 1 mediastinal sarcoma; 1 meningioma; 1 adrenal cortical adenoma. * 1 stomach fibrosarcoma; 1 lymphoma; 1 uterine adenoma. produce any obvious toxic effects; it might therefore be inferred that the dose level.used was not the maximum tolerated dose. While in keeping with the observations made by other authors [4, 7), the present results pro vide limited evidence of carcinogenicity of VDC in rodents. Additional evidence on which to base a final assessment of the carcinogenicity of VDC may be forth coming from studies known to be underway [15]. The oral administration of CP to rats resulted in an incidence of tumours that was no different from that observed in vehicle-treated controls. Results from further investigations, including the use of different species and, possibly, administration by inhalation, are necessary before the carcinogenicity of CP can be as sessed. Acknowledgements The authors acknowledge the technical help of Mrs. B. Euzeby, Mrs. D. Gdestfo, Miss L. Laval, Mrs. N. Lyandrat and Mrs. M.J. Muetion, the help of Miss C.L. Kitchen in the preparation and Mrs. E. Heseltine in the editing of the manuscript. References 1 Ott, M.; Fishbeck. W.; Townsend, J., and Schneider, E.: A health study of employees exposed to vinylidene chloride. J. occup. Med. 18: 735-738 (1976). 2 Thiess, A.M.; Frtntzel-Beyme, R., and Penning, E.: Mortality study of vinylidene chloride exposed persons in the BASF; in Proc. Vth Medichem Congr., San Frandsco 1977 (in press 1979). 3 Jenkins, L.J.; Trabulus. M.J., and Murphy, S.D.: Biochemical effects of 1,1-dichloroethylene in rats: comparison with carbon tetrachloride and 1,2-dichloroethylenc. Toxicol, appl. Pharmacol. 23: 501-510 (1972). 4 Maltoni, C.; Cotti, G.; Morisi, L., and Chieco, P.: Carcinogenicity bioassays of vinylidene chloride. Medna.Lav. 61:241-262 (1977). 5 Rampy, L.W.; Quast, J.F.; Humiston, C.G.; Balmer, M.F., and Scbweu, B. A.: Interim results of two-year toxicological studies in rats of vinylidene chloride incorporated in the drinking water or administered by repeated inhalation. Environ. Health Perspect. 21: 33-43 (1977). 6 Viola, P.L- and Caputo, A. Carcinogenicity studies on vinylidene chloride. Environ. Health Perspect. 2/: 45--47 (1977). 7 Lee, C.C.; Bhandari, J.C.; Winston, J.M.; House, W.B.; Peters, P.J.; Dixon, R.L., and Woods, J.S.: Inhalation toxicity of vinyl chloride and vinylidene chloride. Environ. Health Perspect. 21: 25-32 (1977). 8 Baruch, H.; Malaveille, C.; Moniesano, R., and Tomatis, L,: Tissue-mediated mutagenicity of vinylidene chloride and 2-chloro- URL 20128 / ':WM t -' .: ^ *! * ; - * * *4 . l _ jy- F Carcinogenicity Test of Vinylidene Chloride and Chloroprene in Rats 141 butadiene in Salmonella ryphimurium. Nature, Lond. 225: 641643 (1973). 9 Oettingen, W. von: 2-Chlorobutadiene: its toxicity and pathology and the mechanisms of its action. J. ind. Hyg. Toxicol. 18: 271- 272 (1936). ovary thyroid soft pituitary other 10 Khachatryan, E. A.: Lung cancer morbidity 8mong persons work tissue 1 ing with chloroprene. Vop. Onkot. 18: 85-86 (1972). 11 Khachatryan, E.A.: The role of chloroprene compounds in the 1 t n %n %n %n %n % process of skin neoplasm formation. Gig. Truda, prof. Zabol. 18: 54-53 (1972). 2 12.5 - - - - 1 6.3 4* 25.0 12 Pell, S.: Mortabty of workers exposed to chloroprene. J. occup. Med. 20; 21-29 (1978). -_ 13 Sanotskii, I.V.: Aspects of the toxicology of chloroprene: im 1 1.9 7 13.0 2 3.7 8s 14.8 mediate and long-term effects. Environ. Health Perspect. 17: 85- 9 14.5 1 1.6 - - 2 3.2 .- - 93(1976). -- -- 1 7.1 - - I4 7.1 14 Zilfyan, V.; Fichidzhyan, B.; Garibyan, D., and Pogosova, A.: Experimental study of chloroprene for carcinogenicity. Vop. i. Onkol.23; 61-65 (1977). r -- -- 4 8.2 2 4.1 8s 16.3 15 IARC Monographs on the Evaluation of (he Carcinogenic Risk of i 3 6.4 - - - - - - * 3` 6.4 Chemicals to Humans. Monomers, plastics and synthetic elasto mers, vol. 19 (International Agency for Research on Cancer, Lyon 1979). I 16 Weil, C.S.: Tables for convenient calculation of median effective dose (LDjo or EDso) and instructions in their use. Biometrics 8: 249-263 (1952).' f V. Ponomarkov, Unit of Chemical Carcinogenesis, International Agency for Research on Cancer, 150 Cours Albert-Thomas, 69372 Lyon Ctdex 2 (France) URL 20129 (hvucU&riljj FOLLOW-UP STUDY ON THE CARCINOGENICITY OF VINYL CHLORIDE AND VINYLIDENE CHLORIDE IN RATS AND MICE: TUMOR INCIDENCE AND MORTALITY SUBSEQUENT TO EXPOSURE C B. Hong, ). M. Winston, L. P. Thornburg, C C Lee Pharmacology and Toxicology, Midwest Research Institute, Kansas City, Missouri J. S. Woods Laboratory of Environmental Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina Carcinogenic and other toxic effects In rats and mice were examined during a 12-mo period following exposure to vinyl chloride (VC) or vinylidene chloride (VOC). Exposure of male and female mice to 50, 250, or 1000 ppm VC for 6 hjd, 5 dfwk, for 1, 3, or 6 mo resulted In Increased numbers of deaths and Increased mor/Oundlty at all dose levels during the exposure and postexposure periods, as compared with air-exposed controls. Similar observations were mode with rats after t, 3, 6, or 10 mo exposure ro VC. Cumulative tumor Incidence at various organ sites also Increased In both species during the postexposure period In proportion to dose or duration of exposure at higher dose levels. However, except for mammary gland tumors in female mke, no significant increase in cumulative tumor Incidence occurred In either species at 50 ppm VC or 55 ppm VDC, regardless of duration of exposure. These results suggest that exposure to vinyl halides at dose levels lower than those that elicit a significant increase In cancer incidence during the lifetime of the animat may, nonetheless. Increase the risk of early death or morlbundlty from toxic pre- 'or subcordnogenlc effects. At dost levels higher titan those consistent with the physio logical defense or repair capabilities of the cell, ultimate tumor Incidence becomes proportionate to length of exposure and may reflect the number of carcinogenic events elicited during the exposure period. The authors thank Mr. ). L. Minor for his statistical analysis of the tumor data; Mr. J. K Hagenscn and Mrs. K. J. Smith for their assistance with inhalation, chamber monitoring, and animal care operations; and Mrs. E. R. Ellis for her supervision of histology preparation. This research was supported by contract N01*ES-2*2084 from the National Institute of Environmental Health Sciences. C B. Hong's present address is College of Agriculture, University of Kentucky, Lexington, Kentucky. J. M. Winston's present address is College of Pharmacy, Drake University, Des Moines, Iowa 50311. L P. Thornburg's present address is College of Veterinary Medicine, University of Missouri, Columbia, Missouri 65201. C. C Lee's present address is Health Review Division (TS-792), U.S. Environmental Protection Agency, Washington, D.C. 20460. Requests for reprints should be sent to James S. Woods, Battelle Seattle Research Center, 4000 N.E. 41 st Street, Seattle, Washington 9S105 (present address). *>9 Journal of Toxicology and Environmental Health, 7:909-924,1991 Copyright C 1991 by Hemisphere Publishing Corporation 0098-4109/81 /Q50909-1682.25 & mmm*;: -vF-:. **.*" G 70 i-- NJ O w o N. 1506 CHEMICAL REGULATION REPORTER i and 50 B6C3F1 mice of either sex for 103 weeks. Groups of parable with that of controls, lnlerslitlal-cell tumors of the 50 untreated rats and mice of either sex served as controls. testis occurred at significantly higher incidences in dosed After week 20 in mice and week 40 in rats, mean body weights of high-dose females were lower than those of the male rats than in controls (40/48. 46/46, 48/48); however, this tumor is common in male F344 rats and thus the o untreated controls. No compound-related clinical signs or biological significance of these findings is reduced. No other effects on survival were observed. Feed consumption by dos tumors were observed in increased incidences that were con ed rats and dosed mice of either sex was lower than that of sidered to be related to administration of tara gum to either the controls. No tumors were observed in either species at species. Although the rats and mice might have been able to incidences that were considered to be related to administra tolerate higher doses. 50,000 ppm (5%) is the recommended tion of guar gum. maximum concentration of a test substance mixed in feed, Hepatocellular carcinomas occurred in dosed male mice according to the guidelines of the Bioassay Program. at incidences significantly lower than that in the controls. A significant negative trend was observed in the number of The combined incidence of male mice with either male rats with pancreatic islet cell adenoma. In the numbers hepatocellular adenomas or carcinomas was also of female mice with alveolar/bronchlolar adenomas, and in significantly lower in the high-dose group than In the con the numbers of female mice with hepatocellular adenomas. trols. Under condilons considered adequate for the car Under conditions considered as adequate for the car cinogenesis bioassay of a test material, no evidence was cinogenesis bioassay of a test material, guar gum was not found that tara gum was clearly carcinogenic for F344 rats carcinogenic for F344 rats or B6C3F1 mice of either sex. of B6C3F1 mice of either sex. CUM ARABIC A bioassay for carcinogenicity of gum arabic. a widely used food stabilizer, was conducted by feeding diets con taining 25,000 or 50.000 ppm of the test substance to 50 F344 rats and 50 B6C3FI mice of either sex for 103 weeks. Groups of untreated rats and mice of either sex served as controls. Throughout most of the study, mean body weights of dosed mice of either sex and of dosed male rats were comparable with those of the controls; mean body weights of the dosed female rats were slightly lower than those of the controls. No other compound-related clinical signs or effects on sur vival were observed. Mean daily feed consumption by highdose rats and mice of either sex was 86%-88'e that of the controls. No compound-related lesions were found in mice or rats of either sex. Under the conditions of this bioasay, gum arabic was not carcinogenic for F344 rats or B6C3F1 mice of either sex. TARA GUM A bioassay for carcinogenicity of tara gum, a potential stabilizer for cosmetics and foods, was conducted by feeding diets containing 25,000 or 50,000 ppm of the test substance to 50 F344 rats and 50 B6C3F1 mice of either sex for 103 weeks. Groups of 50 untreated rats and mice of either sex served as controls. In the chronic bioassay, mean body weights of dosed ancj control rats of either sex were comparable over the course of the study; feed consumption by high-dose male rats was comparable with that of the controls and feed consumption by high-dose female rats was 79% that of the controls. Mean body weights of high-dose mice of either sex were lower than those of controls; feed consumption by dosed mice was com VINYLIDENE CHLORIDE A subchronic and a chronic study of vinylidene chloride, a widely used chemical intermediate and monomer, was con ducted in F344 rats and B6C3FI mice. In subchronic studies, groups of 10 rats and 10 mice of either sex were ad ministered vinylidene chloride In com oil by gavage five times per week at 0,5,15, 40,100, or 250 mg/kg body weight for 13 weeks. At the end of this study, all surviving animals were killed and representative tissues from these animals were subjected to histopathologica! examination. The liver was identified as a target organ for vinylidene chloride tox icity. In a 104-week chronic exposure study which was conducted primarily to determine possible carcinogenic potential of vinylidene chloride, the 50 F344 rats and 50 B6C3F1 mice of either sex were gavagod with vinylidene chloride suspended, in com oil at dose levels of 1 or 5 mg/kg in rats and 2 or 10 mg/kg in mice. Groups of 50 rats and 50 mice of either sex received com oil alone and served as vehicle controls. Throughout most of the study, mean body weights of the dos ed rats of either sex and high-dose female mice were com parable with those of the corresponding controls; the mean body weights of dosed male and low-dose female mice were slightly lower than those of the controls. The results of histopathological examination indicated an increased in cidence of necrosis of the liver in high-dose male mice and chronic renal inflammation in high-dose rats of either sex. The carcinogenic effects of the chemical were analyzed statistically and, under the conditions of this bioassay, vinylidene chloride was not carcinogenic for F344 rats or B6C3F1 mice of either sex. & <w EPA FINAL RULES WITH DEFERRED EFFECTIVE DATES 46 FR 11972, Feb. 12, 1981 ENVIRONMENTAL PROTECTION AGENCY (AS-FRL 1752-31 40 CFR Parts 6, 62, S6, 162, 230, 403, 413, and 420; Deferral of Effective Oatea aoemcy: Environments) Protection Agency. action: Notice of deferral of effective dales. summary; This notice defers until March 30.1081. the effective dale of all the regulations listed below. This action is taken pursuant lo Ihe Prcsidenl's order of January 29,1981, requiring postponement of the effective date of pending regulations for 00 days. effective date: The new effective date of all the regulations Haled below will be March 3a 1961; FOR FURTHER INFORMATION CONTACT! Faith Halter. Special Assistant to the Ccneral Counsel, Environmental Protection Agency. 401 M Street. SW., Washington, D.C. 20400. 202-755-0709. SUPPLEMENTARY INFORMATION: The following is a list of ell the regulations whose effective date Is deferred by this notice. 2-2041 Publ<stud by THE BUREAU OF NATIONAL AFFAIRS. INC. WASHINGTON. DC 20037 G \ istcvtivtly throughout set. Proprietary names ' If the paper ms been note. hove the table. Do not tceisary to understand teeutivelv with Arabic etc., anti placed at the phabeticaliy in order of typed consecutively on ft (S.S x 8 in.', column at on the original figure oroximately 30to60%). 1. Standard mechanical wringsize }40). in addiH easily distinguishable r 8.5 x )} in. Grid lines 7 or 8 x 10 in.). Highhe electron micrographs larger than 6.5 x 4.5 in. t. The list should include ach important substance 'estigated. Terms should isult the Information for 1) as adopted by the 11th m (noae cjeepboua. e.g. inute uraiion article (withootcovers) are ^umber of brief reports of cotogy would be advanced bey believe that the rapid 1 The manuscript must be .length must be such that it ? subject to Editorial Board nd Applied Pharmacology , two months of mailing of `ill not be permitted. Each y may be published simuV s--owwremrau ofinterest TOXICOLOGY AND APPLIED PHARMACOLOGY 52, 357-370 (1980) Effects of Vinylidene Chloride on DNA Synthesis and DNA Repair in the Rat and Mouse: a comparative Study with Dimethylnitrosamine1 R. H. Reitz, P. G. Watanabe, M* J, McKenna, J. F. Quast, and P. J. Gehring Toxicology Research Laboratory, Health & Environmental Sciences, USA The Dow Chemical Company, Midland, Michigan 46640 Received March 29, J979; accepted October 6, 1979 Effects ofVinylidene Chloride on DNA SyntbesisandDNA Repair in the Rat and Mouse: A Comparative Study with Dimethylnitrosamine. Reitz, R. H., Watanabe, P. G., McKenna, M. J., Quast, J. F,, and Gehring, P. J. (1980). Toxicol. Appl, Pharmacol. 52, 357-370. Exposure to vinylidene chloride (VDC) vapor has been reported to induce tumors in mice, but rats are apparently insensitive to this effect of VDC. This species difference has been correlated with the greater capacity ofmice to activate VDC to a reactive electrophile which can read with macromolecules. To increase our understanding of the molecular events associated with this species difference, we have investigated the potential of VDC to cause DNA alkylation, DNA repair, and DNA replication in the liver and kidneys ofrats and mice. For comparative purposes, the potent carcinogen dimethylnitrosamine (DMN) was also studied. Male Sprague-Dawley rats and CD-I mice were exposed to 10 and 50 ppm VDC for 6 hr. DNA alkylation after 50 ppm [>4C]VDC was minimal in liver and kidney of both rats and mice (one or two orders of magnitude less than reported for DMN in rats). Similarly, DNA repair in the kidney of mice exposed to 50 ppm VDC was only 38% higher than control values, while DNA repair in the liver of mice injected with 20 mg/kg DMN was elevated 637%. However, tissue damage and increased DNA replication (25fold) were seen in the kidneys of mice exposed to SO and 10 ppm VDC. Comparable effects were not seen in the liver of mice exposed to VDC (50 or 10 ppm) or in the liver or kidneys of rats exposed to 10 ppm VDC. Thus an important distinction between DMN and VDC has been demonstrated. Tumorigenic doses of DMN produced relatively little tissue damage, but were associated with a high degree of DNA alkylation and DNA repair synthesis. In contrast, exposure to tumorigenic doses of VDC resulted in massive tissue damage but induced minimal DNA alkylation or DNA repair synthesis. This suggests that the tumors observed in mice exposed to VDC arise primarily through effects of the chemical on nongenetic components ofthe cells. Consequently protection ofhumans from levels ofVDC sufficient to cause tissue damage should also serve to preclude any carcinogenic activity of VDC. Vinylidene chloride (1,1-dichloroethylene, VDC) is an intermediate in the synthesis of many commercially important plastics. Al though carcinogenicity of this materia] has not been observed in several long-term studies with rats (Viola and Caputo, 1977; Rampy et a!., 1977; Maltoni el <2/., 1977), 1 This study was funded by the companies supporting the vinylidene chloride projects being administered by the Manufacturing Chemists Association, Wash ington, D.C. VDC-related tumors have been reported in mice (Maltoni et al., 1977). Maltoni reported that male mice were fare more sensitive to VDC than females, that the target organ in male mice was the kidney, and that the tumorigenicity of VDC was associated with significant injury to kidney tissue in male mice (Maltoni et al., 1977). Studies by McKenna et al. (1977) have shown that the metabolism of VDC to electrophilic species which bind to cellular 357 004I-008X/80/030357-I4S02.00/0 Cepyrifhi C )9W> by Academic Prtii, Inc. AO right* of reproduction in any form reserved. ft t IP ITO ro o 0-4 'K .ro I I