Dehalogenation of 2,6-dibromobiphenyl and 2,3,4,5,6-pentachlorobiphenyl in contaminated estuarine sediment.

Estuarine sediments from a USEPA Superfund site in coastal Georgia were extensively contaminated with Aroclor 1268, a mixture of highly chlorinated polychlorinated biphenyls used by a former chlor-alkali plant. Batch slurries of contaminated sediment were incubated for 1 yr with amendments of 2,6-dibromobiphenyl (26-BB) and 2,3,4,5,6-pentachlorobiphenyl (23456-CB) under anaerobic, sulfate-reducing conditions and different pH (5.5-7.5). Organic extracts of slurry sub-samples in a time series were analyzed by congener-specific GC-MS. Dechlorination of 23456-CB was pH dependent and occurred via two routes with the sequential loss of (1) meta and para chlorines and (2) para, ortho, and meta chlorines. Quantitative dehalogenation of 26-BB was observed at all pH. Supplementation of nonachlorobiphenyls (as primers) did not induce dechlorination of native Aroclor 1268 nor of the primers themselves. While contaminated estuarine sediments possess microbial consortia with diverse dehalogenating activities, lack of dechlorination of Aroclor 1268 and spiked nonachlorobiphenyl congeners suggests a bioavailability limitation or enzyme-substrate incompatibilities.

Transplantation and chromosomal analysis of cell lines derived from mesotheliomas induced in rats with erionite and UICC chrysotile asbestos.

The histological lesions, chromosomal characteristics and transplantability of 6 erionite-induced and 7 UICC chrysotile-induced rat mesotheliomas are compared. The tumours were of 4 types: tubulopapillary, fibrosarcomatous, mixed fibrosarcomatous and tubulopapillary, and mixed fibrosarcomatous and chondrosarcomatous. Cell lines derived from these tumours displayed heterogeneous chromosome anomalies, but none were unique either to chrysotile or erionite treatment. Six of 7 erionite-induced and 4 of 6 UICC chrysotile-induced tumours had various anomalies of chromosome No. 1. When 7 cell lines were transplanted into syngeneic rats, all produced tumours that were pathologically similar to the original tumour, regardless of the route of injection. Cytogenetically, the cell lines derived from tumours after intrapleural transplantation resembled the injected cell line. The cytogenetic analysis of the cell lines derived from the tumours after subcutaneous transplantation is in progress. The induction period for transplanted tumours was 28-80 days.

Significance of mass and number of fibers in the correlation of V79 cytotoxicity with tumorigenic potential of mineral fibers.

The cytotoxicity of four tumorigenic minerals: erionite(w), erionite(c), UICC crocidolite, UICC chrysotile and nontumorigenic mordenite was compared in Chinese hamster lung V79 cells. The results indicate that the tumorigenic minerals were toxic by showing more than 50% toxicity for at least one dose between 10 and 100 micrograms/ml. Mordenite was nontoxic. Higher potency of erionite, however, was not evident in this system when the dose considered was expressed in mass units. On the other hand, when the degree of cytotoxicity was considered per number of mineral fibers, it was clear that fewer erionite fibers of all three dimensions (A greater than or equal to 3; L greater than or equal to 8.0 micrometers, W less than or equal to 0.25 micrometer; and L less than 5.0 micrometers, W less than or equal to 0.1 micrometer) than those of UICC crocidolite and UICC chrysotile were needed to produce similar toxicity. This suggests that the dose in number of fibers may be a better parameter than the total mass dose as a correlate of tumorigenic potential.

Metaphase and anaphase analysis of V79 cells exposed to erionite, UICC chrysotile and UICC crocidolite.

The cytogenetic effects of erionite treatment of V79 cells were compared with those of UICC crocidolite and UICC chrysotile treatment. A significant reduction in diploid cells with an accompanying increase in aneuploid and polyploid cells was observed with all three treatments. In the erionite-treated cultures, an increase in aneuploidy was observed at all dose levels ranging from 10 to 100 micrograms/ml, whereas in the crocidolite- and chrysotile-treated cultures, significant increases in aneuploidy were observed at all dose levels except the low dose, 10 micrograms/ml. Chromatid aberrations were observed in cultures treated with crocidolite and chrysotile and were especially pronounced at dose 100 micrograms/ml of chrysotile. The clastogenic effect of erionite was weaker but statistically significant at dose 100 micrograms/ml. An extrapolation of these cytogenetic changes over dose in number of fibers suggests that erionite was more reactive than the other two minerals in producing aneuploidy. The number of fibers required to produce a similar degree of cytogenetic effects was several orders of magnitude higher for chrysotile and crocidolite than erionite. These results correlate with the higher tumorigenic potency of erionite. In general, fewer cells treated with erionite entered anaphase than those treated with the other two minerals. As a result, abnormal anaphases representing chromosomal mis-segregation were observed only in the chrysotile- and crocidolite-treated cultures. To our knowledge, this is the first report on cytogenetic effects of erionite.

In vitro effects of mineral fibers.

In vivo tests available to determine the toxicity of mineral fibers are too expensive and time-consuming to be regularly employed in the evaluation of the potential health hazard posed by natural and man-made fibers. In vitro procedures, while economical, convenient and capable of ranking "relative toxicity," are uncertain predictors of specific lesions. Thus, it is of interest to compare the results of various standard in vitro tests with the results of in vivo tests. Data are available for intratracheal and intrapleural exposures of animals to amphibole mineral fibers from UICC amosite and a fibrous form of ferroactinolite. This paper presents data from parallel in vitro studies employing these minerals. The methods used were mammalian erythrocyte lysis, Chinese hamster ovary cell clonal cytotoxicity assay, and rabbit alveolar macrophage cytotoxicity assay. The experiments were conducted in triplicate to determine dose effect by mass and by number of fibers with aspect ratios greater than 3. A comparison of relative toxicity was made between the ferroactinolite and amosite. In the erythrocyte system, there was a greater lytic effect per unit of fibers for ferroactinolite than for the UICC amosite.

Correlation of in vitro and in vivo methods by means of mass dose and fiber distribution for amosite and fibrous ferroactinolite.

Oncogenesis and in vitro data (reported elsewhere in detail) are compared on the basis of relative activity by mass and by dimensional fiber parameters. When tumor induction is compared to the number of fibers of various lengths and aspect ratios in the dose in rats to the degree of tumor induction, a degree of difference with the long thin fiber concept of tumorigenesis by mineral fibers is noted. Consistency is re-established, however, when cognizance is taken of the change in the length and aspect ratio that took place during residence in the lung. This change resulted in a severalfold excess for ferroactinolite of all fiber lengths with high aspect ratios, produced as a result of longitudinal splitting of the introduced fibers. The response by mass in the in vitro procedures did not mimic oncogenesis. When mass was so adjusted that there were an equal number of mineral fibers, aspect ratio greater than 3, for dose for the two minerals, agreement was closer in both the rabbit alveolar macrophage toxicity test and the clonal cytotoxicity assay in Chinese hamster ovary cells. When activity was related to the number of mineral fibers, the same aspect ratio computed to have been contained in the mass dose, agreement with the relative induction of lung tumors was closer. In all cases, erythrocyte lysis was more active in reflecting the number of mineral fibers.

Tumorigenesis by a ferroactinolite mineral.

In lifetime exposure of male Fischer-344 rats to ferroactinolite fibers and to UICC amosite asbestos fibers by means of intratracheal and intrapleural treatments, oncogenesis was greater in the lung for the ferroactinolite and in the pleura for the amosite. The lack of correlation between the effects of the two methods of exposure suggests that in this instance intrapleural inoculation was not a good predictor of pulmonary response on the basis of mass dose. Another feature of the ferroactinolite was that pleural tumors resulted from intratracheal instillations. Conversely, lung tumors or tumorlike lesions were also induced by intrapleural inoculations of ferroactinolite. These facts suggest a greater in vivo transport for the ferroactinolite than for the amosite. Since there are far fewer mineral fibers per mass unit in the ferroactinolite the tumor yield per unit of mineral fibers was strikingly greater by both routes of administration for ferroactinolite than for amosite.

Interpretation of the carcinogenicity of amosite asbestos and ferroactinolite on the basis of retained fiber dose and characteristics in vivo.

Rats were exposed to amosite asbestos and ferroactinolite fibers by intrapleural inoculation and intratracheal instillation. The ferroactinolite sample was found to be more carcinogenic in both exposures than the amosite sample on the basis of total fiber dose or fiber dose expressed for any size category of hypothetical greatest carcinogenic potency. Quantitative transmission electron microscope analysis of low-temperature ashed whole lung samples collected at different times following intratracheal instillation of fibers demonstrated that concentrations and sizes of fibers retained in rat lungs were greatly influenced by the relative ability of each mineral to undergo longitudinal splitting as a consequence of dissolution in vivo. Ferroactinolite fibers rapidly split to produce many thin fibers so that the number of ferroactinolite fibers retained in the lung 2 years after intratracheal instillation was four times greater than the number of fibers originally instilled. The number of short, thin ferroactinolite fibers retained (10-fold more than amosite) after in vivo splitting best explains the greater lung carcinogenicity of ferroactinolite compared to amosite.

Experimental approach to the determination of pulmonary carcinogenic influences of shale oil effluents.

Oil derived from oil shale deposits is known to contain many organic complexes. The formation of carcinogenic hydrocarbons is temperature-dependent and is associated with retorting of the oil. Furthermore, oil shale is a rich source of inorganic elements such as the metals. Biological studies have demonstrated that concentrated extract of tars from combustion of shale oil are carcingenic to the skin of mice. The purpose of the current project is to evaluate the potential carcinogenic hazard from inhalation of retort and combustion effluents for man. These studies will be carried out in pathogen-free rats by intratracheal instillation with and without added factors such supplemental particles and known carcinogens as interactants.

Influence of crystallization habit of minerals on in vitro cytotoxicity.

Four samples of cummingtonite-grunerite series in various crystallization habits were tested in vitro. The cytotoxicity to Chinese hamster ovary cells and hemolysis to sheep erythrocytes were inversely proportional to the structural faults and surface defects of the minerals. At a comparable surface area, asbestiform grunerite (UICC amosite), semi-asbestiform cummingtonite, acicular cummingtonite, and acicular grunerite were found to be cytotoxic and hemolytic in a decreasing order. The influence of particle size on hemolysis and cytotoxicity was observed with acicular grunerite. Although samples of relatively large particle size were found to be inert, samples of smaller particle size were cytotoxic as well as hemolytic. No apparent relationship between surface charge and hemolysis as well as cytotoxicity was observed.