The increases in mRNA expressions of inflammatory cytokines by adding cleaning solvent or tetrachloroethylene in the murine macrophage cell line J774.1 evaluated by real-time PCR

The use of a petroleum-derived cleaning solvent for dry cleaning, instead of tetrachloroethylene (perchloroethylene, PCE), has increased. The cleaning solvent may induce immunological alteration. In this study, murine macrophage-lineage J774.1 cells were exposed to the cleaning solvent at 0, 25, 50, and 75 µg/ml or PCE at 0, 400, 600, 800, and 1,000 µg/ml by vigorous vortexing. Cell viability was determined. The mRNA expressions of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), IL-6, IL-10, IL-12p40 (a dimer of IL-12), and IL-27p28 (a dimer of IL-27) were evaluated by real-time PCR. The mean viabilities in the 50 and 75 µg/ml groups of the cleaning solvent were significantly lower than that of the control. The mean mRNA expressions of TNF-α and IL-1β in the 50 µg/ml group were significantly higher than those in the control. For PCE, the mean viabilities at 600 µg/ml and over were significantly lower than that of the control. The mean expressions of IL-6 and IL-10 in the 800 µg/ml group were significantly higher than that in the control. The productions of IL-1β and TNF-α may be altered in human during intoxication of the cleaning solvent as well as those of IL-6 and IL-10 in human during that of PCE, and these may affect on immune cells.

Conductivity reduction due to emulsification during surfactant enhanced-aquifer remediation. 1. Emulsion transport

Surfactant-enhanced aquifer remediation (SEAR) is a promising technology for the remediation of subsurface zones contaminated with organic liquids. To ensure the success of SEAR, the potential reduction in hydraulic conductivity must be evaluated. The objective of this study was to examine the process of conductivity reduction due to the transport of an emulsion, generated by mixing tetrachloroethylene with 4% solutions of two nonionic surfactants, in packed beds of sand-sized silica particles. The injection of the emulsion resulted in a 75-85% reduction in conductivity, depending on the properties of the surfactant and the porous medium. The greater viscosity of the emulsion relative to that of water accounted for about 25% of the reduction. The remainder was attributed to the clogging of the porous medium by the emulsion. The relative sizes of the emulsion droplets and the packed bed's pores, coupled with measurements of zeta potential of the emulsion droplets and silica particles, suggested that multilayer deposition was the principal mechanism of clogging. This hypothesis was corroborated by direct observation of the emulsion transport process in a micromodel. To simulate the reduction in hydraulic conductivity in these systems accurately, it was necessary to modify the emulsion transport model by Soo and Radke to include the phenomena of viscosity variation and multilayering.

Conductivity reduction due to emulsification during surfactant enhanced-aquifer remediation. 2. Formation of emulsion in situ

Permeability reduction due to surfactant emulsification can impact the effectiveness of surfactant-enhanced aquifer remediation (SEAR). The objective of this study was to examine the process of in situ emulsification in systems composed of tetrachloroethylene (PCE) and solutions of two nonionic surfactants selected for their ability to enhance solubility. The injection of the surfactant solutions into columns packed with sand-sized silica particles containing residual saturations of PCE resulted in the formation of an emulsion with an average droplet diameter of 0.1-0.2 microm, about an order of magnitude smaller than that of the ex situ formed emulsion. The measurements of hydraulic conductivity showed an initial decrease, followed by a gradual increase, with a final steady-state reduction of about 35% after the injection of 7-8 pore volumes of surfactant solution, of which about 8% could be attributed to the deposition of the emulsion. To describe the observed trends, the modified emulsion transport model from Part 1 was modified to include the processes of the formation of the emulsion and the reduction of the PCE residual. The good comparison between the simulations and the experimental data suggests that the model correctly reflects the multiple processes controlling the hydraulic conductivity of the packed columns during surfactant solution injection.

The cytotoxicity of some organic solvents on isolated hepatocytes in monolayer culture

The cytotoxic effects of volatile and water-insoluble organic solvents (ethylbenzene, tetrachloroethylene, n-hexane) were tested on isolated hepatocytes in monolayer culture by using the 3-(4,5 dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) reduction assay. All of the tested compounds inhibited metabolic activity of hepatocytes and this effect depended on the concentration of solvents in the incubatory medium. The presence of fetal calf serum in the medium did not change the cytotoxicity of xenobiotics. IC50 values calculated on the basis of the MTT assay indicated that ethylbenzene was more cytotoxic than tetrachloroethylene and n-hexane. Using hepatocyte monolayer culture and the MTT assay to assess cytotoxicity of organic solvents causes many technical problems. It seems that it cannot be used as a rapid, cheap, and credible method.

An in vitro model for evaluation of vaporous toxicity of trichloroethylene and tetrachloroethylene to CHO-K1 cells

Toxicokinetics of trichloroethylene (TCE) and tetrachloroethylene (PER) in culture medium and their toxicity to CHO-K1 cells were investigated by employing an in vitro vapor exposure system. Cells were cultured in a 60 mm petri dish with a 25 mm glass dish glued in the central area. TCE or PER was added to the central glass dish so that it would evaporate and dissolve in the surrounding medium in which cells were growing. The results showed that the concentration of TCE or PER in medium increased significantly within 20 min and then decreased very rapidly with time. After a 24 h incubation, the residual of TCE or PER in the medium was very low, but was displayed in a dose-dependent manner. Treatment of cells with either TCE or PER resulted in a dose- and time-dependent inhibition of cell growth. A significantly increase in the frequency of micronuclei (MN) was also observed with either TCE or PER treatment. Low doses of TCE (5-20 microl) or PER (1-5 microl) significantly enhanced the intracellular glutathione (GSH) level. However, the level of GSH rapidly decreased with higher doses of TCE (40-80 microl) or PER (10-20 microl). Depletion of cellular GSH showed no effect on the sensitivity of cells to TCE or PER treatment. GSH-conjugation has been proposed as an activation mechanism to account for the nephrotoxicity of TCE and PER, however the toxicity of TCE and PER to CHO-K1 cells is probably mediated through a distinct mechanism.

Methanogenic and perchloroethylene-dechlorinating activity of anaerobic granular sludge

The biodegradation and toxicity of tetrachlorethylene (C2Cl4) and trichloroethylene (C2HCl3) were studied with different anaerobic enrichment cultures using the following electron donors: acetate, propionate, butyrate, methanol, formate and hydrogen. All of them sustained dechlorination except propionate, for which C2Cl4 biodegradation rates were not significant. The best results were obtained with butyrate. Hydrogen appeared to be a relevant electron donor for dechlorination with the present cultures. In the presence of specific inhibitors such as bromoethanesulphonate or molybdate, a slight inhibition of dechlorination was observed. According to dechlorination kinetics, Monod-type behaviour was observed up to 120 microM C2Cl4 or 200 microM C2HCl3 with Ks values around 7 microM for both compounds. Dechlorination was partially inhibited at higher concentrations. In contrast, methanogens, or at least methane production, were more sensitive to the presence of chlorinated ethylenes and inhibitions of methanogenesis was observed to different extents over all the C2Cl4/C2HCl3 concentration range tested, even at the lowest concentrations.

Genotoxic effects of chemicals in the single cell gel (SCG) test with human blood cells in relation to the induction of sister-chromatid exchanges (SCE)

In a comparative study, benzo[a]pyrene (BaP), cyclophosphamide (CP), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and tetrachloroethylene (PER) were tested for their ability to induce genotoxic effects in the single cell gel (SCG) test and the sister-chromatid exchange (SCE) test with human blood cells. MNNG as well as S9 mix activated BaP- and CP-induced DNA effects in both tests in a dose-dependent manner. While the range of concentrations which induced DNA migration or SCE was the same for MNNG and for BaP, much higher CP concentrations were necessary for a positive response in the SCG test than in the SCE test. PER was tested in the absence and in the presence of S9 mix and neither induced DNA migration nor increased SCE frequencies. In these experiments, a clear cytotoxic effect of PER was observed. To investigate a possible influence of DNA repair on the effects in the SCG test, cells were treated for 2 h and further incubated for 1 h after removal of the test substance. This procedure caused a clear decrease in induced DNA migration in experiments with BaP and CP, whereas no reduction was found with MNNG. This modified protocol did not lead to the detection of DNA effects after treatment with PER. The results indicate that the SCG test responds to various DNA lesions and does not seem to be sensitive to non-genotoxic cell killing. Its sensitivity obviously depends on the type(s) of induced DNA lesions and the effects can be modified by DNA repair processes in a complex manner. For the detection of genotoxic properties of chemicals with the in vitro SCG test, a single evaluation at the end of the exposure period seems to be sufficient.

Dichloroacetic acid and related compounds: induction of prophage in E. coli and mutagenicity and mutation spectra in Salmonella TA100

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 (+S9) 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 (+/-S9), DCAC (-S9), and TCAC (+/-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 approximately 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-->A.T transitions, whereas TCAC induced primarily G.C-->T.A transversions, which was also the predominant mutation among the background revertants.(ABSTRACT TRUNCATED AT 250 WORDS)

The efficacy of a hospital dry cleaning cycle in disinfecting material contaminated with bacteria and viruses

It is not known how efficiently a standard dry cleaning cycle can kill bacteria or viruses. In-situ experiments were carried out to determine the cidal activity of such a cycle using perchloroethylene solvent against five clinical bacterial isolates and a DNA bacteriophage. Viable counts of bacteria recovered from material after dry cleaning were reduced by 3-8 logs, with up to 10(3) colony forming units (cfu) surviving per strip. Numbers of bacteriophage were only reduced by 10-100 fold. The resistance of the bacteriophage to solvent and heat (60 degrees C) was compared with that of polio and herpes simplex viruses in vitro. Polio virus and bacteriophage, but not herpes simplex virus, survived exposure to perchloroethylene at room temperature for 40 min. Dry cleaning with perchloroethylene is not bactericidal and is particularly poorly virucidal for non-enveloped viruses.

International comparison of odor threshold values of several odorants in Japan and in The Netherlands

The purpose of this paper is to compare the published odor threshold values of six odorants. In Japan, all of the odor threshold values used in the Offensive Odor Control Law (enacted in 1972) were determined in an odor-free room (4 m3) by a trained panel (20 men, ages 30-45 years who were perfumers) who sniffed the odors directly and made absolute judgments of odor quality and intensity. In The Netherlands, sensorial odor concentration measurements were made with an olfactometer in a mobile sniffing car with eight panelists, four men and four women, ages 18-40 years. Such presentations are repeated with different dilution ratios. Comparison of the threshold data for the six different compounds given as the barely perceptible concentration level revealed striking similarities for hydrogen sulfide (in Japan 0.0005 ppm/in The Netherlands 0.0003 ppm), phenol (0.012/0.010), styrene (0.033/0.016), toluene (0.92/0.99), and tetrachloroethylene (1.8/1.2) but not for m-xylene (0.012/0.12). Such a similarity was not found with any other literature sources.

Perchloroethylene-induced reduction in glial and neuronal cell marker proteins in rat brain

Rats were exposed to continuous inhalation of 300 and 600 p.p.m. of perchloroethylene for 4 and 12 weeks. Exposure to 600 p.p.m. for 4 to 12 weeks resulted in a slower increase in brain weight. Brain region weights, total proteins and DNA were decreased in frontal cerebral cortex and brain stem but not in hippocampus after exposure to 600 p.p.m. for 12 weeks. Four marker proteins were measured to monitor the specific neurotoxic effects of perchloroethylene: S-100 protein and glial fibrillary acidic protein as glial cell markers and neurone specific enolase and neurofilament 68 kD polypeptide as neuronal markers. The concentrations of glial and neuronal cytoskeletal proteins (glial fibrillary acidic protein and neurofilament 68 kD polypeptide) were reduced in frontal cerebral cortex. The total tissue contents of glial proteins (S-100 protein and glial fibrillary acidic protein) were decreased in all 3 brain regions investigated (frontal cerebral cortex, hippocampus and brain stem). Neurone specific enolase was unchanged by perchloroethylene exposure. These results indicate that exposure to perchloroethylene reduces the number of brain cells, possibly glial cells, and interferes with the metabolism of cytoskeletal elements in both glial and neuronal cells.

Assessment of behavioral effects of tetrachloroethylene using a set of time-series analyses

A systematic approach to the analysis of time-series data for spontaneous locomotor activity in the rat was developed to evaluate the behavioral effects of chemical substances. Chronogram, spectral analysis, analysis of the slope of fluctuation, and the cosinor method were used to analyze data obtained by continuously recording spontaneous locomotor activity in the rat. Under synchronized conditions, a circadian period of 24 h was observed and the 1/f fluctuation, in which the power spectral density is inversely proportional to frequency, was confirmed. The 1/f fluctuation was considered to reflect the fractal-like structure of ultradian components of spontaneous locomotor activity. IP administration of 1.0 g/kg body weight of tetrachloroethylene at 0900 h produced a remarkable phase-shift (4.0 +/- 0.9 h) in the activity rhythm and an increase in the slope of fluctuation (0.4 +/- 0.1) in contrast to a relatively smaller decrease in the total amount of spontaneous locomotor activity. These behavioral effects of tetrachloroethylene were dose-dependently lower at lower doses. The present study demonstrated the usefulness of our systematic approach in evaluating the behavioral effects of chemical substances.

Synergistic and antagonistic effects on genotoxicity of chemicals commonly found in hazardous waste sites

Synergistic and antagonistic effects on genotoxicity of mixtures of four chemicals; i.e., lead tetraacetate (LTA), arsenic trioxide (ATO), dieldrin (DED), and tetrachloroethylene (TCE), were evaluated by the Tradescantia-micronucleus (Trad-MCN) assay. The chemicals were mixed in ratios of 1:1, 1:2 and 2:1 for mixtures of two chemicals and 1:1:1 each for three chemicals. The concentration of stock solution of these chemicals was around the minimum effective dose (MED) or below the MED for these chemicals as reported by Sandhu et al. (1989). Treatments were applied to plant cuttings by hydroponic uptake of the mixed solutions through the stems of the plant for 30 h followed by fixation of the flower buds in aceto-alcohol (1:3 ratio) without a recovery period. Microslides were prepared for scoring MCN frequencies. Results of two series of repeated experiments indicated that all mixtures of LTA/ATO exhibited antagonistic effects. On the other hand, all mixtures of TCE and DED exhibited synergistic effect. These data indicate that for evaluating biological hazards at chemical waste sites, it is prudent to evaluate the genotoxicity of complex chemical mixtures as these exist in nature because the biological effects based on evaluating individual chemicals may not be true predictors of the interactive effects of the pollutants.

Renal function in dry cleaning workers exposed to perchloroethylene

Perchloroethylene (PCE) is a widely used dry cleaning and degreasing solvent. Although there is evidence in animals and humans for renal effects at extremely high doses, there are few studies of its potential renal toxicity at typical occupational concentrations. This study reports on the relationship of PCE in breath and estimates of chronic exposure with the urinary ratios of total urinary protein, albumin, and n-acetyl-glucosaminidase (NAG) to creatinine in dry cleaning workers exposed to PCE. Regression models including one or more exposure variables, demographic variables, mean arterial blood pressure (MAP), and the presence of diseases affecting kidney function were examined. Urine samples, breath samples, exposure histories, and medical histories were obtained from 192 dry cleaning workers. The results failed to demonstrate any consistent relationship between exposure and renal outcome variables. However, protein/creatinine and albumin/creatinine were significantly, although weakly and positively, associated with MAP; NAG/creatinine was weakly but significantly positively associated with age; mean NAG/creatinine was also higher in non-whites. The reasons why an association between exposure and renal outcome was not found are discussed.

A study of the effect of perchloroethylene exposure on the reproductive outcomes of wives of dry-cleaning workers

The purpose of this investigation was to compare the reproductive outcomes of wives of men exposed to perchloroethylene in the dry-cleaning industry compared to those of wives of laundry workers. Seventeen female partners of dry cleaners and 32 partners of laundry workers were interviewed. The number of pregnancies and the standardized fertility ratios were similar between the two groups. Wives of dry cleaners did not have higher rates of spontaneous abortions. However, wives of dry cleaners were more than twice as likely to have a history of attempting to become pregnant for more than 12 months or to have sought care for an infertility problem. Cox proportional hazards models indicated that dry-cleaners' wives had half of the per-cycle pregnancy rate of wives of laundry workers, when controlling for other potential confounders (estimated rate ratio of 0.54, 95% C.I. = 0.23, 1.27).

A study of the effect of perchloroethylene exposure on semen quality in dry cleaning workers

The purpose of this investigation was to determine the effects of perchloroethylene (PCE) exposure on human semen quality. We compared the semen quality of 34 dry cleaners with that of 48 laundry workers. We examined the relationships of 17 semen parameters to expired air levels of PCE and to an index of exposure based on job tasks in the last three months. The average sperm concentration was over 80 million for both dry cleaners and laundry workers, but approximately one-quarter of each group was oligospermic. The overall percentage of abnormal forms was similar for the two groups; however, sperm of dry cleaners were significantly more likely to be round (t = -3.29, p = 0.002) and less likely to be narrow (t = 2.35, p = 0.02) than the sperm of laundry workers. These effects were dose-related to expired air levels and to the exposure index after controlling for potential confounders (e.g., heat exposure). The average percent motile sperm for both groups was slightly over 60%; however, sperm of dry cleaners tended to swim with greater amplitude of lateral head displacement (ALH) than those of laundry workers (t = -1.73, p = 0.09), and level of PCE in expired air was a significant predictor of ALH in the multiple regression model (t = 2.00, p = 0.05). In addition, exposure index was a significant negative predictor of the sperm linearity parameter (t = -2.57, p = 0.01). These results suggest that occupational exposures to PCE can have subtle effects on sperm quality. Additional analyses are required to determine whether these effects are associated with changes in fertility.

Genetic effects of chlorinated ethylenes in the yeast Saccharomyces cerevisiae

The chlorinated ethylenes 1,1-dichloroethylene (vinylidene chloride), trans-1,2-dichloroethylene, trichloroethylene, and tetrachloroethylene (perchloroethylene) were assayed for their ability to induce mitotic gene conversion and point mutation as well as mitotic aneuploidy in diploid strains of the yeast Saccharomyces cerevisiae. From strain D7 late logarithmic-phase cells grown in 20% glucose liquid medium, containing a high level of cytochrome P-450, as well as stationary-phase cells combined with an exogenous metabolic activating system (S9) were used, in order to activate the chlorinated compounds and to produce electrophilic mutagenic intermediates. Only 1,1-dichloroethylene exhibited a dose-dependent genetic activity, while the other ethylenes did not. The 2 ways of metabolic activation were compared and were found to cause approximately the same effect. In contrast to the findings with strain D7, vinylidene chloride, trans-1,2-dichloroethylene, and trichloroethylene induced, without metabolic activation, mitotic chromosomal malsegregation in strain D61.M. The presence of liver homogenate as an activating system did not enhance the respective frequencies of chromosome loss. In the case of tetrachloroethylene, sufficient data have not become available, since this compound showed a highly toxic effect towards yeast cells, decreasing the rate of surviving cells to less than 30% at a concentration of 9.8 mM.

Effects of exposure to Freon 11, 1,1,1-trichloroethane or perchloroethylene on the lipid and fatty-acid composition of rat cerebral cortex

Organic solvents are often present as mixtures in various industrial and house-hold products. The adverse effects arising from exposure to these solvents have often been generalized to concern the whole group of solvents. In an examination of the possibility that organic solvents have general effects on experimental animals, rats were continuously exposed to vapors of the halogenated solvents Freon 11, perchloroethylene, and 1,1,1-trichloroethane. The lipid composition and fatty-acid pattern of ethanolamine phosphoglyceride from the cerebral cortex were analyzed. It was observed that only perchloroethylene had effects on the brain lipid composition. Cholesterol and total phospholipids were slightly reduced. Among the fatty acids the proportion of stearic acid was reduced and those of docosapentanoic, 22:5 (N = 6), and of docosahexanoic, 22:6 (N = 3), acids were increased. The changes in the fatty-acid pattern indicate that an alteration occurs in the desaturation of fatty acids. It seems probable that the chloroethylenes have specific effects on the fatty-acid pattern of brain phospholipids not shared by other solvents.

Effects of trichloroethylene, tetrachloroethylene and dichloromethane on soil biomass and microbial counts

Trichloroethylene, tetrachloroethylene and dichloromethane in concentrations of 10, 100, and 1000 micrograms per 100 g brown soil (dry weight) had different effects on soil microorganisms. The ATP content of the soil biomass decreased significantly in the first and second week of incubation when 100 micrograms of trichloroethylene and tetrachloroethylene were added to the soil, and it was strongly reduced during the two months of the experiment duration when 1000 micrograms of the individual chlorinated solvents under test was added. Similar inhibitory effects could be observed with soil fungi. Tetrachloroethylene in a dose of 1000 micrograms, however, exerted mainly a stimulative influence as shown by the counts of oligotrophic and copiotrophic aerobic soil bacteria and also by the total counts of anaerobic microorganisms. The same concentrations of trichloroethylene and dichloromethane inhibited both groups of aerobic bacteria in the soil. Actinomycetes were mainly inhibited by addition of 1000 micrograms of the volatile chlorinated solvents but they were not affected by lower concentrations. No significant effects were observed in aerobic spore-forming bacteria, and only slight effects were found also in the spore-forming anaerobic microorganisms of Clostridium sp. In conclusion, with the concentrations of chlorinated solvents which were from 10(3) to 10(6) higher than the actual 'in situ' soil contamination, some negative effects on soil microorganisms could be observed. However, one or two month after the soil was contaminated, the microbial counts increased again.

Bacterial beta-lyase mediated cleavage and mutagenicity of cysteine conjugates derived from the nephrocarcinogenic alkenes trichloroethylene, tetrachloroethylene and hexachlorobutadiene

The metabolism of beta-lyase and the mutagenicity of the synthetic cysteine conjugates S-1,2-dichlorovinylcysteine (DCVC), S-1,2,2-trichlorovinylcysteine (TCVC), S-1,2,3,4,4-pentachlorobuta-1,3-dienylcysteine (PCBC) and S-3-chloropropenylcysteine (CPC) were investigated in Salmonella typhimurium strains TA100, TA2638 and TA98. The bacteria contained significantly higher concentrations of beta-lyase than mammalian subcellular fractions. Bacterial 100,000 X g supernatants cleaved benzthiazolylcysteine to equimolar amounts of mercaptobenzthiazole and pyruvate. DCVC, TCVC and PCBC produced a linear time-dependent increase in pyruvate formation when incubated with bacterial 100,000 X g supernatants; pyruvate formation was inhibited by the beta-lyase inhibitor aminooxyacetic acid (AOAA). CPC was not cleaved by bacterial enzymes to pyruvate. DCVC, TCVC and PCBC were mutagenic in three strains of S. typhimurium (TA100, TA2638 and TA98) in the Ames-test without addition of mammalian subcellular fractions; their mutagenicity was decreased by the addition of AOAA to the preincubation mixture. CPC was not mutagenic in any of the strains of bacteria tested. These results indicate that beta-lyase plays a key role in the metabolism and mutagenicity of haloalkenylcysteines when tested in S. typhimurium systems. The demonstrated formation in mammals of the mutagens DCVC, TCVC and PCBC during biotransformation of trichloroethylene (Tri), tetrachloroethylene (Tetra) and hexachlorobutadiene (HCBD) may provide a molecular explanation for the nephrocarcinogenicity of these compounds.

Trichloroacetic acid accumulates in murine amniotic fluid after tri- and tetrachloroethylene inhalation

The distribution of trichloroethylene (Tri) and tetrachloroethylene (Tetra) and their metabolites have been studied in pregnant mice by means of whole-body autoradiography (14C-labelled Tri and Tetra) and gas chromatography, with special emphasis on possible uptake and retention in the foetoplacental unit. Volatile (non-metabolized) activity appeared at short intervals after a 10 min. or 1 hr inhalation period in foetus and amniotic fluid. Most notable, however, was a strong accumulation and retention (peak at 4 hrs) in amniotic fluid of the metabolite trichloroacetic acid (TCA) after inhalation of either of the solvents. The main metabolite of Tri, trichloroethanol (TCE) (or conjugates), did not accumulate specifically as compared to maternal plasma. TCA infused intravenously in the maternal plasma was accumulated in amniotic fluid, but less pronounced than after Tri and Tetra inhalation, indicating that some metabolism of Tri and Tetra to TCA may occur in the foetoplacental unit. The results suggest that TCA may be transported to the foetus partly paraplacentally through foetal membranes and amniotic fluid, with the possibility of foetal swallowing or absorption through the skin. Foetal urinary activity also suggests that circulation between foetus and amniotic fluid may contribute to the long-term retention in the foetoplacental unit. In the mother, after inhalation exposures, and in intraperitoneally injected newborn mice, non-extractable radioactivity was found in the respiratory tract, liver, and kidney, indicating binding to these organs through metabolism.

Effects of organic solvents on motor activity in mice

Groups of male mice were exposed via inhalation to methylene chloride, perchloroethylene, toluene, trichloroethylene or 1,1,1-trichloroethane. The exposures were started at 2300 h. Generation of vapor was stopped after 1 h. Motor activity of the animals during the exposures was measured with a Doppler radar. Several concentrations of each solvent were tested. Concentrations could be found for all solvents at which they initially increased the motor activity. When the generation of vapor was terminated and the concentration started to decline, a new phase of changes in motor activity was induced. At this phase, motor activity was in most cases influence in the opposite direction to that at the beginning of the exposure. Trichloroethylene concentrations could be found which gave no increase in activity at the start of exposure but a prominent decrease at termination. The lowest concentration at which effects could be seen was different for the different solvents. Perchloroethylene was more and 1,1,1-trichloroethane less potent than the other solvents in inducing motor activity. The time pattern of the motor activity alterations was specific for each solvent. Both the concentration and the rate of the concentration increase were responsible for the effects on motor activity. The differences between the solvents probably reflect differences in their site of action, their distribution and their biotransformation.

Perchloroethylene: effects on body and organ weights and plasma butyrylcholinesterase activity in mice

The effects of continuous and intermittent inhalation of perchloroethylene (PCE) on plasma butyrylcholinesterase (BuChE) activity, organ weights, liver morphology and motor activity in mice (strain NMRI) were tested. PCE exposure increased plasma BuChE activity in a time- and concentration dependent manner in both sexes. The increase was statistically significant at 37 p.p.m. in animals continuously exposed for 30 days. BuChE increased approximately 1.5 times in females and 2.5 times in males after 120 days exposure to 150 p.p.m. After rehabilitation of animals exposed for 30 days to 150 p.p.m., BuChE levels returned to normal. Liver weight also increased in a time and concentration dependent manner. Both sexes exhibited significant liver enlargement at 9 p.p.m. The increase was about 2.3 in females and 1.9 in males after continuous exposure to 150 p.p.m. for 120 days. After rehabilitation (120 days) of animals exposed to 150 p.p.m. for 30 days, a 10% increase still remained. A decrease in body weight gain was seen in both sexes after exposure to concentrations above 75 p.p.m. Female kidney weight was slightly increased. No clear effect on spleen weight could be detected. When the same time-weighted average concentration was used, intermittent exposure for 30 days had similar effects on liver weight and BuChE activity as continuous exposure, even when exposures lasted for only one hour per day. Liver cell morphology was changed after PCE exposure. The alterations could be observed already at 9 p.p.m. but disappeared after rehabilitation.

Genetic and biochemical studies on perchloroethylene 'in vitro' and 'in vivo'

Perchloroethylene (PCE) was tested in a diploid strain (D7) of the yeast Saccharomyces cerevisiae in suspension tests with and without a mammalian microsomal activation system (S9) and 'in vivo' by the intrasanguineous host-mediated assay. In addition, enzyme alteration studies were performed in mice non-pretreated or pretreated with phenobarbital + beta-naphthoflavone. PCE did not induce any genetic effect either 'in vitro' or 'in vivo'. In the suspension test, PCE was more toxic without metabolic activation and less toxic with mammalian microsomal activation. The enzymatic determinations showed an increase of the aminopyrine demethylase activity and of the level of cytochrome P-450.

Transforming activities of trichloroethylene and proposed industrial alternatives

Three chlorinated hydrocarbons, proposed or already in use as industrial substitutes for the hydrocarbon trichloroethylene, were tested for in vitro transforming potential in a Fischer rat embryo cell system (F1706), which previously has been shown to be sensitive to transformation by chemical carcinogens. Trichloroethylene and the three substitutes (1, 1, 1 trichloroethane, tetrachloroethylene and methylene chloride) all were found to induce transformation, the three substitutes being equal or more efficient transforming agents.

[Metabolism of m-xylene in rats after administration of chlorinated hydrocarbons (author's transl)]

Male albino rats of the Donryu strain were divided into 4 groups: the normal control group, tetrachloromethane (CCl4, TCM) group, tetrachloroethylene (CCl2 = CCl2, PCE) group and trichloroethylene (CHCl = CCl2, TCE) group. Each group was consisted of 6 animals. TCM, PCE and TCE were administered orally at a dosage of 13 mmoles/kg as a 50% v/v olive oil solution to rats 24 hours prior to an oral administration of m-xylene (8.2 mmoles/kg as a 50% v/v olive oil solution). The normal control group was administered only olive oil (2.5 ml/kg) 24 hours prior to m-xylene dose. Urine was collected 24, 48, 72 and 96 hours after administration of m-xylene. The urine was analysed for m-methylhippuric acid (m-MHA) by the paper chromatographic method of Ogata et al. The results obtained were as follows: 1) Total urinary excretion of m-MHA in the normal control group was equivalent on a molar basis to about 58% of m-xylene received, and the major portions of the metabolites were excreted on the 1st day. 2) In TCM group, total urinary excretion of m-MHA was about a half of that in the normal control group. It was equivalent on a molar basis to about 30% of m-xylene received (p less than 0.01), and the urinary excretion of m-MHA on the 1st day was significantly less than those of the normal control group (p less than 0.001) and TCE group (p less than 0.05). 3) In PCE group, urinary excretion of m-MHA on the 1st day was significantly less than that of the normal control group (p less than 0.01) and the excretion was delayed. 4) In TCE group, total urinary excretion of m-MHA was slightly but not significantly less than that of the normal control group (p less than 0.05). 5) In TCM-ip group of rats which were given TCM orally 24 hours prior to the administration of m-xylene by intraperitoneal injection, urinary excretion of m-MHA on the 1st day and in 4 days after administration of m-xylene was less than that of the control-ip group.