[Apropos of folliculosis caused by chlorinated hydrocarbons (chlorine acne)].
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Acne Vulgaris↗
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Results for “Hydrocarbons, Chlorinated”
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Distal site and surface mutations of cytochrome P450 1A2 markedly enhance dehalogenation of chlorinated hydrocarbons.
Chlorinated compounds such as chlorinated ethylenes and ethanes are serious environmental pollutants. In the present study, we examined whether or not a recombinant strain of Saccharomyces cerevisiae that expresses rat liver cytochrome P450 1A2 (P450 1A2) wild-type and mutant proteins can efficiently catalyze oxidative and reductive dehalogenations of trichloroethylene, pentachloroethane, and hexachloroethane. Mutations at putative heme distal and protein surface sites of P450 1A2 greatly enhanced turnover values toward those substrates under both aerobic and anaerobic conditions. For example, a Thr319Ala mutation at the putative heme distal site enhanced the degradation rate of trichloroethylene and pentachloroethane by 2- and 2.7-fold, respectively, under aerobic conditions. The Thr319Ala mutation also strongly facilitated the reaction with hexachloroethane up to 13- and 4.5-fold under aerobic and anaerobic conditions, respectively. The Thr319Ala mutation increased dechlorinated over protonated product ratios by 3-fold as well when either pentachloroethane or hexachloroethane was used as a substrate. A Lys250Leu mutation on the putative protein surface site enhanced the dehalogenation rate of hexachloroethane up to 4.8-fold under anaerobic conditions. In contrast, a Glu318Ala mutation at the putative distal site markedly decreased the activities with trichloroethylene and pentachloroethane substrates under aerobic conditions. Conserved amino acids Thr319 and Glu318 at the heme distal site have been suggested to be important in the O2 activation during monooxidation reactions of P450s. However, the present study indicates that Thr319 is likely to be an inhibitor of dechlorination of trichloroethylene and penta- and hexachloroethanes. The roles of Thr319, Glu318, and Lys250 in the catalysis with chlorinated hydrocarbons are discussed in association with reaction mechanisms.
Animals↗
Hydrocarbons and chlorinated hydrocarbons in the air in the greater Split area.
The content of hydrocarbons and chlorinated hydrocarbons was examined in samples of air from the greater Split area. Organic pollutants were accumulated from the air by adsorption on Polysorb-10 and desorption with hot water vapour. Gaseous and liquid phases were analysed by gas chromatography. Hydrocarbon concentrations were within permissible limits and their effects on human health were negligible. There were marked differences between pollutant concentrations in air samples taken from the industrial zone, crossroads in the city centre and "clean" zones.
Air Pollutants↗
[Hydrocarbons and chlorinated hydrocarbons in groundwater].
The contribution deals with the following topics: --Microbiological in situ investigations of polluted ground water aquifers in order to develop a concept for biological remediation. --Removal of organic and halogenated organic compounds from ground water using methods which are common in the drinking water treatment (sand-fastfiltering, immobilized reactors). --Removal of organic and halogenated organic compounds from ground water using methods which are common in sewage treatment (activated sludge, suspension reactors). The conclusion has been drawn that there are many microbiological methods existing which can be used to remove the above contaminants from soil and ground water environments.
Bacteria↗
Chlorinated hydrocarbon solvents.
Chlorinated hydrocarbon solvents, such as trichloroethylene and 1,1,1-trichloroethane, have been used widely in many industries because of their ready ability to dissolve oils, greases, and other materials, their low acute toxicity, and their non-flammability. Although these materials share certain toxicologic, functional, and chemical similarities, important differences exist. These differences largely explain why certain solvents, once common, are no longer in use and why others have become more widely used over time. This article reviews the properties, toxicologic effects of interest, workplace limits, and use history of the most common chlorinated hydrocarbon solvents.
Humans↗
Hair and its associated lipids as an excretory pathway for chlorinated hydrocarbons.
1. Chlorinated hydrocarbon insecticides and other halogenated compounds, probably biphenyls, were found to be associated with human hair at concentrations less than 1 p.p.m. 2. In experiments with rats, chlorinated 14C-hydrocarbon insecticides and polychlorinated biphenyls were excreted in hair in all instances, but excretion was less with the more labile compounds. 3. Excretion via hair may be a significant factor in eliminating chlorinated hydrocarbons which resist metabolism.
Animals↗
Relationships between tissue concentrations of chlorinated hydrocarbons (polychlorinated biphenyls and chlorinated pesticides) and antioxidative responses of marine mussels, Perna viridis.
Marine mussels, Perna viridis, were transplanted from a reference site to various polluted sites around Hong Kong. After 30 d of exposure, antioxidative responses in the gills and hepatopancreas and tissue concentrations of chlorinated hydrocarbons [polychlorinated biphenyls (PCBs) and chlorinated pesticides (CPs)] were determined for individual mussels. Glutathione S transferase (GST) and glutathione (GSH) were positively correlated with tissue PCB concentrations. Only one of the enzymatic antioxidants, glutathione peroxidase (GPx), showed significant response to tissue PCB. No significant correlation was found between tissue concentrations of chlorinated hydrocarbons and other enzymatic antioxidants (superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and NADPH DT-diaphorase (DT-d). Oxidative stress, measured as thiobarbituric acid reactive substances, was correlated with chlorinated pesticide concentrations in tissues. This study demonstrated a correlation between GST/ GSH and chlorinated hydrocarbons. The apparent lack of correlation between trace organic pollutants and some of the enzymatic antioxidants may be due to the inhibitory effects caused by these chemicals. The above results suggest that more investigations are needed before these enzymes can be used as biomarkers.
Animals↗
Determination of polynuclear aromatic hydrocarbons contaminated with chlorinated hydrocarbon pesticides.
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Adipose Tissue↗
Interactions of chlorinated hydrocarbon insecticides with membranes.
Chlorinated hydrocarbon insecticides quench the fluorescence of N-alkyl derivatives of carbazole. We used phospholipids with covalently attached carbazole as probes for the interactions of chlorinated hydrocarbon insecticides with lipid bilayers, the object being to understand better the toxicities of chlorinated hydro-carbons. Fluorescence quenching measurements revealed the lipid-water partition coefficients of the chlorinated hydrocarbons, their diffusion coefficients in the membranes, and the binding capacities of the membranes for the chlorinated hydrocarbons. Active insecticides were compared with inactive analogues to test whether activities correlated with chlorinated hydrocarbon-membrane interactions. Thus DDT and methoxychlor were compared with inactive DDE, and insecticidal gamma-lindane was compared with three less active stereoisomers. The partition coefficients, diffusion coefficients and membrane saturation capacities did not correlate with insecticidal potency. The partition coefficients of these chlorinated hydrocarbons were larger in bilayers containing unsaturated fatty acyl chains as compared to bilayers containing saturated fatty acyl chains. Interestingly, neural membranes are known to contain a large percentage of unsaturated lipids. Our results indicate that the activities of chlorinated hydrocarbons are not a result of specific interactions of these compounds with the lipids of membranes. However, the neurotoxicity of chlorinated hydrocarbons may be amplified by selective partitioning in the unsaturated neural membranes.
Diffusion↗
Microbiological aspects of the removal of chlorinated hydrocarbons from air.
Chlorinated hydrocarbons are widely used synthetic chemicals that are frequently present in industrial emissions. Bacterial degradation has been demonstrated for several components of this class of compounds. Structural features that affect the degradability include the number of chlorine atoms and the presence of oxygen substituents. Biological removal from waste streams of compounds that serve as a growth substrate can relatively easily be achieved. Substrates with more chlorine substituents can be converted co-metabolically by oxidative routes. The microbiological principles that influence the biodegradability of chlorinated hydrocarbons are described. A number of factors that will determine the performance of microorganisms in systems for waste gas treatment is discussed. Pilot plant evaluations, including economics, of a biological trickling filter for the treatment of dichloromethane containing waste gas indicate that at least for this compound biological treatment is cost effective.
Air Microbiology↗
[Determination of chlorinated hydrocarbons in coffee beans].
Chlorinated hydrocarbons (gamma-HCH, DDT and their analogous metabolites) were determined in coffee beans. Four sorts of green coffee beans and 18 sorts of burnt coffee beans were used in the research. The method was based on extraction of fat and its destruction with concentrated sulphuric acid. Chlorinated hydrocarbons were extracted with n-hexane, separated and quantitatively determined by gas chromatography. The presence of chlorinated hydrocarbons was detected in green coffee beans and, in smaller quantities, in burnt coffee beans. The concentration of chlorinated hydrocarbons was lower in medium and darkly burnt coffee beans than lightly burnt coffee. The level of DDT and its metabolites in final product decreased after coffee burning at higher temperatures. After brewing the grind coffee beans the remains of chlorinated hydrocarbons were detected in coffee-grounds at concentration to those found in coffee beans. Drinking of natural coffee does not influence an increase of intake the chlorinated hydrocarbons by human beings.
Coffee↗
Methods for the analysis of persistent chlorinated hydrocarbons in tissues.
Chlorinated hydrocarbons bioaccumulate in tissues and may have severe health consequences. These compounds occur individually, in small groups or as complex mixtures; examples of each category include aldrin, hexachlorocyclohexane and the polychlorinated biphenyls. Tissue extraction and purification schemes have been established, although new approaches such as supercritical fluid extraction are promising. Analyses often require the resolving power of capillary gas chromatography, in combination with the sensitivity and selectivity of electron-capture detection, electrolytic conductivity detection and mass spectrometry. Difficulties arise in quantitating chlorinated hydrocarbons in tissues, due to the number of components present and the fact that individual constituents may be reduced or enhanced in concentration in tissues, compared with the original formulation. Congener specific analysis and computer-assisted identification techniques have been applied to the problem.
Chromatography↗
Considerations concerning the murine hepatocarcinogenicity of selected chlorinated hydrocarbons.
Of the chlorinated hydrocarbons discussed above, all six are associated with induction of hepatocellular neoplasia in mice. None of the six is considered to be potent mutagen and most are without any significant genotoxic activity as assessed by conventional in vitro testing schemes. Although some of the agents have biological effects in common (see Figure 4), there is no single biological response (mode of action) that they all share to provide a mechanistic basis for the observed murine hepatocarcinogenicity. Based upon the information currently available for each of the chlorinated hydrocarbons discussed above, it is probable that some modes of action may be more contributory to the rodent carcinogenic response than others; however, no mode of action, pathway, or mechanism should be considered to be mutually exclusive. The murine hepatocarcinogenic effect of TriCE is most probably contingent upon its species-specific metabolism to trichloroacetic acid and DCA. There is fairly consistent evidence that cytotoxicity and reparative hyperplasia are associated with doses of TriCE that cause induction of liver neoplasms. The possibility that peroxisome proliferation is playing a role in the induction of mouse hepatocellular neoplasia remains a tempting explanation, since higher intracellular steady states of H2O2 production would be consistent with observed enhanced cellular proliferation as well as the possibility of in vivo DNA damage. The mouse hepatocarcinogenicity associated with TetCE most probably is associated with species-specific metabolic production of trichloroacetic acid. As with TriCE, cytotoxicity and reparative hyperplasia may represent a potential mode of action for the observed hepatocarcinogenicity. Once again, the potential for enhanced peroxisome proliferation is consistent with enhanced cell proliferation and oxygen radical damage would help explain the random point mutations in ras proto-oncogenes documented in DNA from TetCE-induced mouse liver tumors. DCA-induced mouse hepatocellular neoplasia is probably influenced by cytotoxicity and reparative hyperplasia, but there is also recent evidence that DCA may directly damage DNA, implying an in vivo genotoxic mechanism may be operational. Likewise, altered expression of several genes suggests that subversion of signal transduction may play a role in the induction or progression of liver tumor development. As with TetCE and TriCE, a role for peroxisome proliferation is still a consideration, although the liver tumor response is obvious at doses too low to cause peroxisome proliferation.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Formation of chlorinated hydrocarbons from the reaction of chlorine atoms and activated carbon.
The reactions of chlorine atoms and activated carbon have been studied over the temperature range of 200-400 degrees C using an isothermal flow reactor in conjunction with 337 nm laser photolysis of Cl2. These studies have shown that carbon tetrachloride is the major product, with chloroform, methylene chloride, and methyl chloride being formed in progressively decreasing yields. Trace quantities of methane, ethane, and dichloroethylenes were also observed. Mechanisms of carbon fragmentation by successive addition of chlorine atoms are proposed. The formation of small chlorinated hydrocarbons by the direct reaction of chlorine with carbon may be a key link in both the de novo and precursor pathways of formation of PCDD/F.
Carbon↗
Temporal variation in chlorinated hydrocarbons in healthy women.
Chlorinated hydrocarbons may increase breast cancer risk. Most epidemiological studies addressing this possibility have used one biological sample to measure a subject's cumulative exposure to these compounds. Little is known about short-term temporal variation in organochlorines, particularly in individuals with low levels. Thus, the reliability of using one sample to assess blood levels of chlorinated hydrocarbons in an epidemiological study is unknown. To better understand the temporal changes in blood measures among women with nonoccupational exposures to these compounds, we collected two 5-ml blood samples, an average of 2 months apart, from each of 31 nonfasting healthy women, ages 45-81 years. Samples were assayed for 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), polychlorinated biphenyls (PCBs), and trans-nonachlor in blinded, matched pairs. Results were adjusted for estimated total plasma lipids. The correlations between the two blood samples were high for DDE and PCBs (lipid-adjusted, r = 0.96 and r = 0.89, respectively). For trans-nonachlor, the correlation was relatively poor (lipid-adjusted r = 0.57); however, with the removal of one outlier, the correlation improved substantially (lipid-adjusted, r = 0.90). The mean difference between the two blood samples in unadjusted [-0.36 ng/ml, 95% confidence interval (CI), -0.97, 0.24 ng/ml, P = 0.23] and lipid-adjusted (-0.035 microgram/g lipid; 95% CI, -0.124, 0.055; P = 0.44) DDE levels was small. Similarly, there was little change in the mean difference for unadjusted (-0.14 ng/ml; 95% CI, -0.53, 0.25 ng/ml; P = 0.47) and lipid-adjusted (0.006 microgram/g lipid; 95% CI, -0.050, 0.062; P = 0.82) PCB levels. The mean differences in trans-nonachlor levels between the two blood draws were also small: unadjusted (-0.03 ng/ml; 95% CI, -0.07, 0.02 ng/ml; P = 0.20) and lipid-adjusted (-0.003 microgram/g lipid; 95% CI, -0.010, 0.004; P = 0.33). These data suggest that temporal changes in organochlorine levels within a 1 to 3-month period are minimal for noncancer patients and that a single measure for estimating exposure is highly reliable for DDE and PCB. For trans-nonachlor, however, where the correlation between blood draws was lower, three samples would be needed for estimating exposure; if an outlier is removed from our data, however, then we can conclude that only a single measure is sufficient. These data, therefore, offer no clear conclusion for the use of a single measurement for trans-nonachlor.
Aged↗
Reproductive and morphological condition of wild mink (Mustela vison) and river otters (Lutra canadensis) in relation to chlorinated hydrocarbon contamination.
We assessed chlorinated hydrocarbon contamination of mink and river otters on the Columbia and Fraser River systems of northwestern North America, in relation to morphological measures of condition. We obtained carcasses of mink and river otters from commercial trappers during the winters 1994-1995 and 1995-1996. Necropsies included evaluation of the following biological parameters: sex, body mass and length, age, thymus, heart, liver, lung, spleen, pancreas, kidney, gonad, omentum, adrenal gland and baculum masses, baculum length, and stomach contents. Livers were analyzed, individually or in pools, for residues of organochlorine (OC) pesticides, polychlorinated biphenyls (PCBs), dibenzo-p-dioxins, and dibenzofurans. Contaminant levels were relatively low compared to those documented in other North American populations, although they ranged higher than those detected during an earlier survey (1990-1992) of these regional populations. Body condition varied slightly among collection regions, but showed no relationship with contaminant burden. Mink from the upper Fraser River had less fat stores and also had some of the lowest OC contamination levels observed. Similarly, a few individuals with enlarged livers and kidneys had low contaminant levels. Although a few individual animals with gross abnormalities of reproductive systems did not show high levels of contamination, there was a significant negative correlation between total PCB concentrations (as Aroclor 1260) and baculum length in juvenile mink (r = 0.707; p = 0.033; n = 8). The association of juvenile baculum length with eventual reproductive success is unknown, but further characterization of reproductive organ morphology and relationship to contaminants should be undertaken in a larger subset of these populations.
Aging↗
Interactions of chlorinated hydrocarbons with steroid hormones.
Effects of chlorinated hydrocarbons of the DDT class in mammals were examined. Two effects were considered: a) induction of hepatic mixed function oxidase (MFO), and b) estrogenic activities. The induction of MFO was discussed primarily with reference to the enhancement of steroid hydroxylation. In turn, the increase in steroid hydroxylation by chlorinated hydrocarbons was usually accompanied by a decrease in the biological activity of endogenous and administered steroid hormones. The estrogenic activity of chlorinated hydrocarbons was found to reside primarily in the o,p'-DDT (a major contaminant of technical grade DDT). The mechanism of the estrogenic activity by DDT homologs was explored. It appears that o,p'-DDT acts like estradiol (E2). Similarly to E2, o,p'-DDT binds to the uterine cytosolic receptor. Furthermore, like E2, o,p'-DDT is a potent inducer of certain uterine enzymes. For instance induction of ornithine decarboxylase of about 200-fold was observed with a high dose (250 mg/kg body wt); however as little as 5 mg/kg of o,p'-DDT exhibited marked induction of this enzyme--about threefold. The above activities of the chlorinated hydrocarbons were considered with respect to the potential long-term toxic effects which these compounds might elicit.
Animals↗
In vitro uptake and transfer of chlorinated hydrocarbons among human lipoproteins.
The uptake, distribution, and exchange of chlorinated hydrocarbon insecticides (dieldrin and chlordecone) and biphenyls (2,4,5-2',4',5'-hexachlorobiphenyl and 3-chlorobiphenyl) among human lipoproteins was examined by fluorescence quenching, gel filtration, and ultrafiltration. The chlorinated hydrocarbons were rapidly taken up from solution or silica particles by lipoproteins. The distribution of chlorinated hydrocarbons among the lipoproteins was independent of the amount taken up by the lipoproteins. The partition coefficient for each lipoprotein and the serum concentration of individual lipoproteins determined the distribution pattern of chlorinated hydrocarbons among lipoproteins. The chlorinated hydrocarbons attached to albumin or one of the lipoproteins were rapidly transferred to all other lipoproteins. The exchange was complete in less than one minute. The role of rapid exchange of chlorinated hydrocarbons among lipoproteins in removal of these chemicals from blood and distribution to other tissues is discussed.
Biphenyl Compounds↗