Abstract  15 hazardous industrial waste samples were evaluated for mutagenicity in the Salmonella plate-incorporation assay using strains TA98 and TA100 in the presence and absence of Aroclor 1254-induced rat liver S9. Dichloromethane/methanol extracts of the crude wastes were also evaluated. 7 of the crude wastes were mutagenic, but only 2 of the extracts of these 7 wastes were mutagenic; extracts of 2 additional wastes also were mutagenic. In addition, 10 of the crude wastes were administered by gavage to F-344 rats, and 24-h urine samples were collected. Of the 10 raw urines evaluated, 3 were mutagenic in strain TA98 in the presence of S9 and β-glucuronidase. The 3 crude wastes that produced these 3 mutagenic urines were, themselves, mutagenic. Adequate volumes of 6 of the 10 raw urines were available for extraction/concentration. These 6 urines were incubated with β-glucuronidase and eluted through Sep-Pak® C18 columns; the methanol eluates of 3 of the urines were mutagenic, and these were the same 3 whose raw urines also were mutagenic. In general, the C18/methanol extraction procedure reduced the cytotoxicity and increased the mutagenic potency of the urines. To our knowledge, this is the first report of the mutagenicity of urine from rodents exposed to hazardous wastes. Based on the present results, the use of only strain TA98 in the presence of S9 might be adequate for general screening of hazardous wastes or waste extracts for genotoxicity. The urinary mutagenesis assay does not appear to be a useful adjunct to the Salmonella assay for screening hazardous wastes. The problems associated with chemically fractionating diverse types of hazardous wastes for bioassay are also discussed.

Abstract  We performed three types of studies to evaluate the genotoxicity of the chlorinated organic solvent perchloroethylene (PERC or tetrachloroethylene) and its volatile metabolites, trichloroacetyl chloride (TCAC) and trichloroacetic acid (TCA), as well as the volatile metabolites of trichloroethylene, i. e. dichloroacetyl chloride (DCAC), dichloroacetic acid (DCA), and 2,2,2-trichloroethanol (TCE). In the first set of studies, which involved the evaluation of these chemicals in the Microscreen prophage-induction assay, only DCA (³S9) was genotoxic, producing 6.6–7.2 plaque-forming units/mM. This places DCA among the weakest of the >100 chemicals that have been identified previously as inducers of prophage in this assay. In the second set of studies, which involved the evaluation of these chemicals in the vapor state in Salmonella TA100 using a Tedlar® bag vaporization technique, DCA (³/–S9), DCAC (–S9), and TCAC (³/–S9) were mutagenic, producing 3–5x increases in revertants/plate relative to the background. S9 enhanced the mutagenic potency of DCA but had no effect on the mutagenic potency of TCAC. The potencies ranged from 0.7 to 3.9 rev/p. p. m., resulting in a potency ranking of DCA > DCAC {approx} TCAC. The lowest effective concentrations were 50–300 p. p. m., which are similar to those for ethylene oxide and epichlorohydrin in this assay. In the third set of studies, the mutation spectra of DCA, DCAC, and TCAC were determined at the base-substitution allele hisG46 of Salmonella TA100. DCA and DCAC induced primarily G · C {uparrow} A · T transitions, whereas TCAC induced primarily G · C {uparrow} T · A transversions, which was also the predominant mutation among the background revertants. The DCAC and DCA mutation spectra might be explained by a mutational mechanism in which the compounds are metabolized to etheno adducts on cytosine, causing the DNA polymerase to misincorporate. This report is the first demonstration of the mutagenicity of DCA and of the mutation spectrum of any of these chlorinated organics. In conjunction with previous studies, these results support consideration of a genotoxic mechanism for the carcinogenicity of PERC and trichloroethylene because of the mutagenicity of their metabolites, including DCA.

Abstract  The frequency and mutation spectra of proto-oncogene activation in hepatocellular neoplasms induced by tetrachloroethylene, trichloroethylene and dichloroacetic acid were examined to help define the molecular basis for their carcinogenicity. H-ras codon 61 activation was not significantly different among dichloroacetic acid- and trichloroethylene-induced and combined historical and concurrent control hepatocellular tumors (62%, 51% and 69% respectively). The mutation spectra of H-ras codon 61 mutations showed a significant decrease in AAA and increase in CTA mutations for dichloroacetic acid- and trichloroethylene-induced tumors when compared to combined controls. The H-ras codon 61 mutation frequency for tetrachloroethylene-induced tumors was significantly lower (24%) than that of combined controls and also that of the two other chemicals. Mutations at codons 13 and 117 plus a second exon insert contributed 4% to the total H-ras frequencies for trichloroethylene and tetrachloroethylene. There was also a higher incidence of K-ras activation (13%) in tetrachloroethylene-induced tumors than in the other chemically induced or control tumors. Four liver tumors were found to contain insertions of additional bases within the second exon of K- or H-ras. These findings suggest that exposure to dichloroacetic acid, trichloroethylene and tetrachloroethylene provides a selective growth advantage to spontaneously occurring mutations in codon 61 of H-ras and, at the same time, is responsible for a small number of unique molecular lesions suggestive of either a random genotoxic mode of action or a non-specific result of secondary DNA damage. However, the absence of ras activation in many of the liver neoplasms suggests that alternative mechanisms are also important in B6C3F1 mouse hepatocarcinogenesis.

Abstract  The mutagenicity of the volatile organic chemicals most commonly found as contaminants in New Jersey potable water supplies has been evaluated using the Ames Salmonella/mammalian microsome preincubation assay protocol. Trichloroethylene, tetrachloroethylene, 1,1,1-trichloroethane, methylene chloride, trans-1,2-dichloroethylene, carbon tetrachloride, benzene and 1,2-dichloroethane were investigated using the TA 97a, TA 98, TA 100 and TA 102 strains of Salmonella typhimurium. The mutagenicity of each compound acting singly and in concert with each of the other substances studied was tested. No mutagenicity was observed for benzene, trichloroethylene or trans-1,2-dichloroethylene. Methylene chloride was found to be mutagenic to TA 98 and induced mutagenesis above the background level in TA 102. 1,2-dichloroethane appeared to be slightly mutagenic to TA 100 and more so with TA 102. Preliminary results indicated that tetrachloroethylene, carbon tetrachloride and 1,1,1-trichloroethane may induce mutagenesis in TA 97a. Data comparing the mutagenicity of these substances when acting in pairs will be compared with that obtained when acting alone.

Abstract  Seventeen chemicals (solvents, insecticides and intermediates in the production of textiles and resins) were tested in a short-term in vitro system with human lymphocytes to determine their toxic action. The parameters studied were the tritiated thymidine uptake and cell viability in cultures grown with or without a rat liver metabolizing system (S-9 mix). Data obtained showed that 1,3-dichlorobenzene, 1,2-dichlorobenzene, hexane, 1,2-diiodoethane, 1,4-dichlorobenzene, tetrachloroethylene, 2,3-dibromopropanol, chloromethyl methyl ether, 1,2- and 1,3-dibromopropane, in order, exerted the more toxic effects; ethyl acetate, cyclohexane, cyclohexanone and benzene showed lower toxic activity. The chemicals lost their toxic power in the presence of the metabolizing system with the exception of 1,2- and 1,3-dichlorobenzene which maintained in some degree their toxicity even in the presence of the S-9 mix. Only chloromethyl methyl ether elicited unscheduled DNA synthesis acting as DNA damaging agent.

Abstract  MultiCASE has the ability to automatically determine the structural features responsible for the biological activity of chemicals. In the present study, 93 chemicals tested for their ability to induce chromosomal ‘malsegregation' in the yeast Saccharomyces cerevisiae were analyzed. This ‘malsegregation' mimics molecular events that occur during human development and carcinogenesis resulting in an effective loss of one chromosome of an autosomal pair and duplication of the homologue. Structural features associated with the ability to induce such chromosome loss and duplication were identified and compared with those obtained from examination of other toxicological data bases. The most significant structural similarities were identified between the induction of chromosomal malsegregation and several toxicological phenomena such as cellular toxicity, induction of sister chromatid exchanges in vitro and rodent developmental toxicity. Very significant structural similarities were also found with systemic toxicity, induction of micronuclei in vivo and human developmental toxicity. Less significant structural overlaps were found between yeast malsegregation and rodent carcinogenicity, DNA reactivity and mutagenicity, and the induction of chromosome aberrations in vitro and sister chromatid exchanges in vivo. These overlaps may indicate mechanistic similarities between the induction of chromosomal malsegregation and other toxicological phenomena. The predictivity of the SAR model derived from the present data base is relatively low, however. This may be merely a reflection of the small size and composition of the data base, however, further analyses suggest that it reflects primarily the multiple mechanisms responsible for the induction of chromosomal malsegregation in yeast and the complexity of the phenomenon.

Abstract  14C-Perchloroethylene is covalently bound to DNA, RNA and proteins of rat and mouse organs in vivo after ip injection. Covalent Binding Index values are typical of weak-moderate and weak initiators, for mouse and rat liver, respectively. The greater amounts of labelings detected in mouse liver and in rat kidney macromolecules are consistent with the known toxic and carcinogenic actions of this compound. In vitro binding of perchloroethylene to nucleic acids and proteins proceeds through the involvement of the P-450-dependent mixed function oxidase system from liver microsomes. Kidney, lung and stomach microsomal fractions are uneffective. Cytosolic enzymes from all assayed organs are much more efficient than liver microsomes in bioactivating the compound. GSH addition to liver microsomal system greatly enhances binding extent. This observation suggests that GSH plays a role in the binding of perchloroethylene metabolites as for symmetrically substituted haloethanes.

Abstract  Dichloroacetic acid (DCA), a disinfection by-product of chlorination found in drinking water, is a hepatocarcinogenic in the B6C3F1 mouse. Previous studies have shown that DCA does not significantly alter the incidence of Ha-ras codon 61 mutations in male mouse liver carcinomas from that observed in spontaneous tumors (approximately 50% have Ha-ras mutations) but it alters the proportions of mutations that occur in Ha-ras codon 61. Twenty-two tumors were produced in female B6C3F1 mice after treatment with 3.5 g DCA per liter of drinking water over a period of 104 weeks. To detect potential Ha-ras mutations in the liver tumor tissue of female B6C3F1 mice, genomic DNA was isolated from tumors that had been frozen. The polymerase chain reaction (PCR) and single-stranded conformational polymorphism (SSCP) was used to screen tumor DNA for mutations in Ha-ras exon 2. In DNA from liver tumors in female B6C3F1 mice induced by DCA-treatment we found only one mutation in exon 2 among the 22 tumors analyzed (4.5%). Direct-sequencing of exon 2 revealed a CAA to CTA transversion in Ha-ras codon 61. The result of this study indicates that tumor formation in DCA-treated female B6C3F1 mice is, therefore, not associated with a mutationally activated Ha-ras codon 61. This result differs from previous results obtained in male B6C3F1 mice.

Abstract  The clastogenicity of tetrachloroethylene (tetra) was detected by means of the micronucleus assay using hepatocytes and relticulocytes from ddY male mice, to understand its effects in upon hepatocellular carcinomas in mice. The frequency of micronucleated hepatocytes of mice that received a single injection of tetra after partial hepatectomy increased to levels that were significantly higher than those of controls treated with solvent. However, the micronucleus assay using peripheral blood reticulocytes from ddY male mice, revealed that tetra did not induce to a statistically significant increase in micronucleus frequency. These results suggested that tetra metabolites have a clastogenic effect in vivo upon mouse liver but not upon bone marrow cells.

Abstract  Forty-one chemicals were tested for their abilities to induce trifluorothymidine resistance in L5178Y mouse lymphoma (MOLY) cells. These chemicals were included in the National Toxicology Program's evaluation of four in vitro short-term toxicity assays for predicting carcinogenicity in the rodent bioassay. Of the 41 chemicals examined for this report, 8 were equivocal in the rodent bioassay, and 7 were questionable in-the MOLY assay. If these chemicals are eliminated from an analysis of concordance, the remaining 26 chemicals lead to a concordance of 69% with a sensitivity of 71%. The specificity could not be determined because only two non-carcinogens were detected.

Abstract  Perchloroethylene (PERC) is used widely as an industrial dry cleaning solvent and metal degreaser. PERC is an animal carcinogen that produces increased incidence of renal adenomas, adenocarcinomas, mononuclear cell leukemia, and hepatocellular tumors. Oxidative DNA damage and lipid peroxidation were assessed in 38 women with (dry cleaners) or without (launderers) occupational exposure to PERC. PERC exposure was assessed by collecting breathing zone samples on two consecutive days of a typical work week. PERC levels were measured in blood drawn on the morning of the second day of breathing zone sample collection in dry cleaners and before a typical workday in launderers. Blood PERC levels were two orders of magnitude higher in dry cleaners compared to launderers. A significant correlation was noted between time weighted average (TWA) PERC and blood PERC in dry cleaners (r=0.7355, P<0.002). 8-Hydroxydeoxyguanosine (8-OHdG), ng/mg deoxyguanosine (dG) in leukocyte nuclear DNA was used as an index of steady-state oxidative DNA damage. Urinary 8-OHdG, microg/g creatinine was used as an index of oxidative DNA damage repair. Urinary 8-epi-prostaglandin F(2alpha) (8-epi-PGF), ng/g creatinine was used as an index of lipid peroxidation. The mean+/-S.D. leukocyte 8-OHdG in launderers was 16.0+/-7.3 and was significantly greater than the 8.1+/-3.6 value for dry cleaners. Urinary 8-OHdG and 8-epi-PGF were not significantly different between dry cleaners and launderers. Unadjusted Pearson correlation analysis of log transformed PERC exposure indices and biomarkers of oxidative stress indicated a significant association in launderers between blood PERC and day 1 urinary 8-OHdG (r=0.4661, P<0.044). No significant associations between exposure indices and biomarkers were evident in linear models adjusted for age, body mass index, race, smoking (urinary cotinine, mg/g creatinine) and blood levels of the antioxidants Vitamin E and beta-carotene. The mean+/-S.D. leukocyte 8-OHdG value in control white women was 17.8+/-7.4 and was significantly greater than the 11.8+/-5.9 in control black women. No significant differences by race were evident for the other biomarkers. Smoking status was not significantly associated with any of the oxidative damage indices. Results indicate a reduction in oxidative DNA damage in PERC exposed dry cleaners relative to launderers, but PERC could not clearly be defined as the source of the effect.

Abstract  BACKGROUND: This multicentre population-based case-control study was conducted to estimate the urothelial cancer risk for occupational exposure to aromatic amines, polycyclic aromatic hydrocarbons (PAH), and chlorinated hydrocarbons besides other suspected risk factors. METHODS: In a population-based multicentre study, 1035 incident urothelial cancer cases and 4298 controls matched for region, sex, and age were interviewed between 1991 and 1995 for their occupational history and lifestyle habits. Exposure to the agents under study was self-assessed as well as expert-rated with two job-exposure matrices and a job task-exposure matrix. Conditional logistic regression was used to calculate smoking adjusted odds ratios (OR) and to control for study centre and age. RESULTS: Urothelial cancer risk following exposure to aromatic amines was only slightly elevated. Among males, substantial exposures to PAH as well as to chlorinated solvents and their corresponding occupational settings were associated with significantly elevated risks after adjustment for smoking (PAH exposure, assessed with a job-exposure matrix: OR = 1.6, 95% CI: 1.1-2.3, exposure to chlorinated solvents, assessed with a job task-exposure matrix: OR = 1.8, 95% CI: 1.2-2.6). Metal degreasing showed an elevated urothelial cancer risk among males (OR = 2.3, 95% CI: 1.4-3.8). In females also, exposure to chlorinated solvents indicated a urothelial cancer risk. Because of small numbers the risk evaluation for females should be treated with caution. CONCLUSIONS: Occupational exposure to aromatic amines could not be shown to be as strong a risk factor for urothelial carcinomas as in the past. A possible explanation for this finding is the reduction in exposure over the last 50 years. Our results strengthen the evidence that PAH may have a carcinogenic potential for the urothelium. Furthermore, our results indicate a urothelial cancer risk for the use of chlorinated solvents

Abstract  The administration of lipid-lowering drugs to rodents, notably those related to clofibrate, rapidly provokes a hepatic response characterized by hepatomegaly, proliferation of smooth endoplasmic reticulum and proliferation of peroxisomes in hepatocytes. In some studies hepatocellular carcinoma has been found in rats or mice exposed for their entire life-span to high dose levels of various fibrates. In the present study liver biopsy samples were obtained from 38 hyperlipidemic patients, 28 of whom had been receiving fenofibrate for between 2 months and approximately 3 years (mean values: males 1.79, females 1.98 years). The remaining 10 patients had never been treated with a lipid-lowering drug. Examination of the biopsy samples by a variety of optical techniques and by electron microscopy failed to reveal any difference between the groups. Peroxisomes were relatively rare, there being no evidence of the clear proliferation seen in rodent studies. Other microscopic features of interest were some variation of nuclear size, mitochondria containing paracrystalline inclusions, dilated endoplasmic reticulum associated with reduced amounts of rough endoplasmic reticulum, and the presence of lipid droplets in the liver cells. However, these variations from normal were in general not much more apparent in samples from the fenofibrate-treated patients than in the untreated group. Light- and electron-microscopic observations did not suggest liver intoxication or a carcinogenic pattern.

Abstract  The visible-light-responsive photoelectrochemical and photocatalytic properties of nanoparticles of C(60), partially hydrolyzed aluminum phthalocyanine chloride (denoted as AlPc), and a composite of the two are reported. The three types of nanoparticles were obtained through a reprecipitation method from N-methyl-2-pyrrolidone solutions of C(60), aluminum phthalocyanine chloride (AlPcCl), and their mixture, respectively. The nanoparticle composite's ultraviolet-visible absorption, diffuse-reflectance and Fourier transform IR spectra, X-ray diffraction pattern, and scanning electron microscopy image are all similar to the sum of those of the C(60) and AlPc particles, respectively. The nano-ordered composite exhibits p/n junctionlike photoelectrochemical characteristics, which were investigated in comparison with those of vapor-deposited C(60) (n-type), AlPcCl (p-type), C(60)/AlPcCl (n/p), and AlPcCl/C(60) (p/n) electrodes. The nanoparticle composite further shows photocatalytic activity for the decomposition of trimethylamine to carbon dioxide in a suspension system.

Abstract  BACKGROUND: Tetrachloroethylene, also known as perchloroethylene or

Abstract  The principal aim of the study was to estimate the level of exposure to organic solvents of graffiti removers, and to identify the chemicals used in different cleaning agents. A secondary objective was to inform about the toxicity of various products and to optimise working procedures.

Exposure to organic solvents was determined by active air sampling and biological monitoring among 38 graffiti removers during an 8-h work shift in the Stockholm underground system. The air samples and biological samples were analysed by gas chromatography. Exposure to organic solvents was also assessed by a questionnaire and interviews.

Solvents identified were N-methylpyrrolidone (NMP), dipropylene glycol monomethyl ether (DPGME), propylene glycol monomethyl ether (PGME), diethylene glycol monoethyl ether (DEGEE), toluene, xylene, pseudocumene, hemimellitine, mesitylene, ethylbenzene, limonene, nonane, decane, undecane, hexandecane and gamma-butyrolactone. The 8-h average exposures [time-weighted average (TWA)] were below 20% of the Swedish permissible exposure limit value (PEL) for all solvents identified. In poorly ventilated spaces, e.g. in elevators etc., the short-term exposures exceeded occasionally the Swedish short-term exposure limit values (STEL). The blood and urine concentrations of NMP and its metabolites were low. Glycol ethers and their metabolites (2-methoxypropionic acid (MPA), ethoxy acetic acid (EAA), butoxy acetic acid (BAA), and 2-(2-methoxyethoxy) acetic acid (MEAA)) were found in low concentrations in urine. There were significant correlation between the concentrations of NMP in air and levels of NMP and its metabolites in blood and urine. The use of personal protective equipment, i.e. gloves and respirators, was generally high.

Many different cleaning agents were used. The average exposure to solvents was low, but some working tasks included relatively high short-term exposure. To prevent adverse health effects, it is important to inform workers about the health risks and to restrict the use of the most toxic chemicals. Furthermore, it is important to develop good working procedures and to encourage the use of personal protection equipment.

Abstract  Cause specific mortality was surveyed among 37,682 male employees with three or more days of service between 1940 and 1982 at the Midland or Bay City, Michigan, locations of Dow Chemical USA. Vital status was ascertained through 1982 for 97.5% of the cohort members, and death certificates were obtained for 97.1% of the 7,751 decedents. Comparisons of observed mortality with expected levels based on any of three general population groups (US, Michigan, or seven local counties) consistently demonstrated lower mortality in the cohort from each of the major causes of death, including total malignant neoplasms. Unique among hourly employees was significant excess mortality in the categories of cancer of other lymphatic tissue, and motor vehicle accidents, and both hourly and salaried nonexempt employees experienced significantly higher mortality from other and ill-defined cancers. The influence of duration of employment and age at and period of hire were explored with the Mantel-Haenszel method as adapted for a cohort study. Results were evaluated both including and excluding the mortality experience of subsets of employees with past exposure to known human carcinogens (arsenic, asbestos, bis-chloromethyl ether, benzene, organic dyes, and vinyl chloride). The use of the general mortality survey in monitoring whether or not there are major health problems among the employees and in setting research priorities is emphasized.

Abstract  To evaluate the risk of cancer and other diseases among workers engaged in aircraft manufacturing and potentially exposed to compounds containing chromate, trichloroethylene (TCE), perchloroethylene (PCE), and mixed solvents.

A retrospective cohort mortality study was conducted of workers employed for at least 1 year at a large aircraft manufacturing facility in California on or after 1 January 1960. The mortality experience of these workers was determined by examination of national, state, and company records to the end of 1996. Standardised mortality ratios (SMRs) were evaluated comparing the observed numbers of deaths among workers with those expected in the general population adjusting for age, sex, race, and calendar year. The SMRs for 40 cause of death categories were computed for the total cohort and for subgroups defined by sex, race, position in the factory, work duration, year of first employment, latency, and broad occupational groups. Factory job titles were classified as to likely use of chemicals, and internal Poisson regression analyses were used to compute mortality risk ratios for categories of years of exposure to chromate, TCE, PCE, and mixed solvents, with unexposed factory workers serving as referents.

The study cohort comprised 77,965 workers who accrued nearly 1.9 million person-years of follow up (mean 24.2 years). Mortality follow up, estimated as 99% complete, showed that 20,236 workers had died by 31 December 1996, with cause of death obtained for 98%. Workers experienced low overall mortality (all causes of death SMR 0.83) and low cancer mortality (SMR 0.90). No significant increases in risk were found for any of the 40 specific cause of death categories, whereas for several causes the numbers of deaths were significantly below expectation. Analyses by occupational group and specific job titles showed no remarkable mortality patterns. Factory workers estimated to have been routinely exposed to chromate were not at increased risk of total cancer (SMR 0.93) or of lung cancer (SMR 1.02). Workers routinely exposed to TCE, PCE, or a mixture of solvents also were not at increased risk of total cancer (SMRs 0.86, 1.07, and 0.89, respectively), and the numbers of deaths for specific cancer sites were close to expected values. Slight to moderately increased rates of non-Hodgkin's lymphoma were found among workers exposed to TCE or PCE, but none was significant. A significant increase in testicular cancer was found among those with exposure to mixed solvents, but the excess was based on only six deaths and could not be linked to any particular solvent or job activity. Internal cohort analyses showed no significant trends of increased risk for any cancer with increasing years of exposure to chromate or solvents.

The results from this large scale cohort study of workers followed up for over 3 decades provide no clear evidence that occupational exposures at the aircraft manufacturing factory resulted in increases in the risk of death from cancer or other diseases. Our findings support previous studies of aircraft workers in which cancer risks were generally at or below expected levels.

Abstract  This study was performed to clarify the toxicological profiles of trichloroethylene (TRCE) and tetrachloroethylene (TECE) when they are administered intraperitoneally in mice. The ED50 for loss of righting reflex were 2596 mg/kg in TRCE and 4209 mg/kg in TECE. TRCE and TECE impaired bridge test performance at 500 and 2000 mg/kg, respectively. An operant behavior performance was also inhibited by TRCE at 1000 mg/kg and by TECE at 2000 mg/kg. Both TRCE and TECE exhibited anticonflict effects in a Vogel-type task at 500 mg/kg. This effect was confirmed by the finding that TRCE exhibited anticonflict action in a Geller-type paradigm at 250 mg/kg and more, as did TRCE did at 1000 mg/kg. These results show that TRCE and TECE affect various behaviors in mice and suggest that conflict behaviors are one of the most sensitive behavioral indicators of the effects of these substances. The toxicological profiles of TRCE and TECE with respect to behavioral effects were very similar, and they can be classified in a single category.