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PubMed2005

Co-amendment with halogenated compounds enhances anaerobic microbial dechlorination of 1,2,3,4-tetrachlorodibenzo-P-dioxin and 1,2,3,4-tetrachlorodibenzofuran in estuarine sediments.

Halogenated coamendments enhanced dechlorination of 31 microM of spiked 1,2,3,4-tetrachlorodibenzo-p-dioxin (TeCDD) and 49 microM of spiked 1,2,3,4-tetrachlorodibenzofuran (TeCDF) in sediments from San Diego Bay (CA, USA) and Tuckerton (NJ, USA). Dechlorination of 1,2,3,4-TeCDD occurred to a greater extent under methanogenic than under sulfate-reducing conditions. The most effective stimulation of 1,2,3,4-TeCDD dechlorination occurred with coamendment of 25 microM of 1,2,3,4-tetrachlorobenzene (TeCB), 2,3,4,5-tetrachloroanisole (TeCA), 2,3,4,5-tetrachlorophenol, or 2',3',4'-trichloroacetophenone plus 500 microM lactate and 500 microM propionate as electron donors. The 1,2,3,4-TeCDD dechlorination was evident after three months and sequentially produced mainly 1,2,4-trichlorodibenzo-p-dioxin, 1,3-dichlorodibenzo-p-dioxin, and 2-monochlorodibenzo-p-dioxin (MCDD). Monobromophenols (2-bromo-, 3-bromo-, and 4-bromophenol), monochlorophenols (2-chloro-, 3-chloro-, and 4-chlorophenol), 2,3,5,6-tetrachlorobenzoate, or electron donors alone stimulated less 1,2,3,4-TeCDD dechlorination, with activity apparent only after six months. The 1,2,3,4-TeCDD dechlorination produced 50 mol % 2-MCDD after six months in sediments from the more contaminated Graving Dock and Paleta Creek sites in San Diego Bay. The 1,2,3,4-TeCDD dechlorination by sediments from the less contaminated Shelter Island site in San Diego Bay and in pristine Tuckerton sediments did not produce 2-MCDD. Dechlorination of 1,2,3,4-TeCDF to tri- and dichlorinated daughter products was significantly enhanced by TeCB and TeCA. These results suggest that halogenated aromatic compounds with structural similarity to 1,2,3,4-TeCDD/F stimulate bacteria with the ability to dechlorinate chlorinated dibenzo-p-dioxin and furans.

Anaerobiosis↗
PubMed2001

Reproductive, biochemical, physiological, and population responses in perch (Perca fluviatilis L.) and roach (Rutilus rutilus L.) downstream of two elemental chlorine-free pulp and paper mills.

Perch (Perca fluviatilis L.) and roach (Rutilus rutilus L.) populations in a state of late vitellogenesis were studied downstream of two pulp and paper mills and at upstream references in southern Lake Saimaa, Finland. The mills used elemental chlorine-free bleaching and activated sludge effluent treatment technologies. The exposure of fish to pulp mill effluents, as measured by concentrations of chlorophenolics in the bile and liver ethoxyresorufin-O-deethylase (EROD) activity, was low and almost similar to the references. Nevertheless, bile resin acid concentrations in exposed perch and roach (260-320 micrograms/ml) and bile beta-sitosterol concentrations in exposed roach (1.5-3.5 micrograms/ml) were, respectively, 10 to 30 times and 2 to 5 times higher compared with the references. Reproductive parameters like plasma 17 beta-estradiol and testosterone levels were lower in exposed male and female perch but the same in roach. Vitellogenin concentrations in plasma and liver cytosol of roach were similar. Gonad weight and fecundity were lower in exposed female perch but similar in roach. The relative liver weight was higher in exposed roach but not in perch. The body condition and immunologic parameters in fish were the same. The growth and age at maturity of exposed perch and roach were similar to the references. The size and age distribution of perch in the recipient of one of the mills was shifted toward smaller and younger fish. Our results show that several reproductive variables were altered in late vitellogenic perch in the vicinity of the mills, but they were not altered in roach.

Animals↗
PubMed2004

Solid-phase microextraction of phenol compounds using a fused-silica fiber coated with beta-cyclodextrin-bonded silica particles.

A novel solid-phase microextraction (SPME) fiber was prepared by coating an HPLC beta-cyclodextrin bonded silica stationary phase (CDS) on the surface of a fused-silica fiber. The fiber was evaluated for the determination of five phenol compounds (phenol, 2,4-dimethylphenol, 4-nitrophenol, 3-chlorophenol, 4-methylphenol). Compared with commercially available polymer coatings, the CDS coating showed high sensitivity and fast velocity of mass transfer for phenol compounds because of its porous structure and a unique molecular structure of beta-cyclodextrin. In addition, the CDS coating was proved to be very stable at a relatively high temperature (up to 300 degrees C). The method was suitable for the determination of phenol compounds in aqueous samples. The determination of 4-nitrophenol in soil by microwave-assisted extraction (MAE) coupled to solid-phase microextraction was also investigated.

Journal Article↗
PubMed1993

Effect of dietary protein and sulfur-containing amino acids on urinary metabolites in rats injected with chlorobenzene.

Rats were fed for 10 days a 10 or 20% casein diet, or the diets with 0.3% DL-methionine or L-cystine. Rats fed the 20% casein exceeded those fed the 10% casein in growth, hepatic glutathione (GSH) levels, and microsomal drug-metabolizing activities including cytochrome P-450, aminopyrine N-demethylase, and aniline hydroxylase. Supplement with methionine or cystine had significantly elevated hepatic GSH, regardless of the casein content. After the feeding, rats were intraperitoneally injected with chlorobenzene (0.5 mmol/kg body weight), and the urinary metabolites (4-chlorophenylmercapturic acid (4-CPMA), 2-, 3- and 4-chlorophenol (CPs), 4-chlorocatechol (4-CC), and 2-, 3- and 4-chlorophenylmethylsulfide (CPMSs) ) were measured for 24 hours post-injection. Rats fed the 20% casein exceeded those fed the 10% casein in 4-CPMA, CPs, and in total urinary metabolites. Supplement with methionine or cystine to the 10% casein significantly increased 4-CPMA and decreased 4-CC. Supplement with methionine or cystine to the 20% casein also significantly increased 4-CPMA excretion, but had no effect on urinary 4-CC. The highest urinary excretion of CPMSs was observed in rats fed the 10% casein. Both increase of dietary protein and addition of the sulfur-containing amino acids decreased urinary CPMSs. These results indicate that total urinary metabolites are strongly associated with the microsomal drug-metabolizing activity, formation of the mercapturic acid is dependent on the hepatic GSH level, and the urinary CPMS level is independent on the mercapturic acid formation.

Amino Acids, Sulfur↗
PubMedDate not supplied

Kinetics and mechanism of chlorobenzene degradation in aqueous samples using advanced oxidation processes.

Degradation of chlorobenzene using various photoinduced oxidation processes such as direct ultraviolet light-induced photolysis (UV), UV-H2O2, UV-O3, and UV-H2O2-O3 was investigated under aerobic and anaerobic conditions. Kinetics and mechanisms of the degradation process were studied using high performance liquid chromatorgraphy (HPLC) and gas chromatorgraphy-mass spectrometry (GC-MS). In all cases, loss of chlorobenzene followed first-order kinetics. For UV-induced degradation of chlorobenzene, the observed pseudo first-order rate constant, k(obs), ranged from 1.8 x 10(-4) s(-1) under anaerobic conditions to 6.4 x 10(-4) s(-1) for oxygen-saturated solution. Among the four systems studied, under identical conditions, the degradation rates for UV-H2O2 and UV-H2O2-O3 were very similar and were an order of magnitude higher than the one observed for UV. For the UV-H202 system, the observed pseudo first-order rate constant varied linearly with [H2O2] and followed the rate expression k(obs) = kOH[H2O2], where kOH is the observed second-order rate constant for the reaction of OH radical with cholorbenzene. A plot of k(obs) vs. [H2O2] gave a value of 0.17+/-0.02 M(-1) s(-1) for kOH. Both HPLC and GC-MS studies showed that depending upon the time of photolysis and the advanced oxidation processes (AOP) method employed, various intermediates were formed during the degradation process. For the UV process, these intermediates were identified as phenol, biphenyl, chlorobiphenyl isomers, and benzaldehyde. For the other three systems, chlorophenol, and various isomers of chlorobiphenyl and dichlorobiphenyl, were observed as the intermediates. The initial pH of the solution decreased from 5.8 to 3.5, showing the release of chlorine from cholobenzene. The HPLC results also showed that at longer times, the subsequent degradation of the intermediates also took place. Carbon dioxide and water are suspected to be the likely end products. Mechanistic schemes for the formation of such intermediates are proposed.

Chlorobenzenes↗
PubMedDate not supplied

Nonlinear estimation of microbial and enzyme kinetic parameters from progress curve data.

A computer program (BIOKINFIT) was developed to estimate microbial and enzyme kinetic parameters from progress curve data by nonlinear regression. BIOKINFIT overcomes the limitations associated with parameter estimation in nonlinear equations that are implicit in the dependent variable by numerically approximating the substrate concentration in the integrated kinetic expressions. The simplex method was used to minimize the error between experimentally observed and theoretically predicted substrate depletion data. The robustness of this approach was initially verified using synthetic substrate depletion data that were characterized by either simple or relative errors of known magnitude. Subsequently, previously published data from three different experiments including the pyruvate kinase reaction, 2-chlorophenol biodegradation, and glucose uptake by Penicillium chrysogenum were used to verify the utility of the present approach for kinetic parameter estimation. In all cases, experimental substrate depletion data were accurately described by the theoretical curves and kinetic parameter estimates obtained in this study using the simplex method were in close agreement with those reported previously. BIOKINFIT, available free of charge on request, offers a convenient and robust method of analyzing progress curve data in implicit kinetic expressions.

Biodegradation, Environmental↗
PubMed2004

From phenoxyacetic acids to cellular telephones: is there historical evidence for the precautionary principle in cancer prevention?

In the late 1970s, the author and his colleagues published the first scientific evidence of an association between exposure to phenoxyacetic acids and chlorophenols and certain malignant tumors; the study subjects were also exposed to contaminating dioxins such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The results have been corroborated in other studies. Over the years, industry and its allied experts have attacked these studies, but in 1997 IARC classified TCDD as a human carcinogen, Group I. The author and colleagues found an increased risk of non-Hodgkins lymphoma (NHL) for subjects exposed to these chemicals or to some persistent organic pollutants; the increasing incidence in Sweden leveled off in about 1990. The author postulated that the regulation of or ban on these chemicals in Sweden in the 1970s contributed to the now decreasing incidence of NHL. Recent findings of an association between cellular telephones and brain tumors have provoked much unfounded criticism from industry and from the Swedish Radiation Protection Authority. Thus the precautionary principle is prohibited and early warnings of a cancer risk ignored. The experience of cancer risks from certain chlorinated phenols may serve as a model of how the precautionary principle could be used to take early warnings seriously. Unfortunately, the lessons of history seem to go unheeded, as exemplified by the case of cellular telephones.

Acetates↗
PubMed1998

Agent Orange in war medicine: an aftermath myth.

Since the late 1970s several epidemiological studies have appeared linking exposure to phenoxy herbicides or chlorophenols to some malignant tumors. Most of these compounds are contaminated with dioxins and dibenzofurans; for example, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a contaminant of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), a component of Agent Orange which was sprayed in Vietnam during the war. The results of some of the epidemiological studies on cancer risks associated with exposure to these compounds have been manipulated and misinterpreted, particularly by the Australian Royal Commission on the Use and Effects of Chemical Agents on Australian Personnel in Vietnam. Furthermore, a book on Australian war history entitled Medicine at War, commissioned by the Federal Government, reiterates several of these misinterpretations, despite available contrary evaluations from Australian and U.S. authorities. These remarkable and confusing circumstances in the scientific process are considered also in the light of the recent classification of TCDD as carcinogenic to humans, Group 1, by a Working Group at the International Agency for Research on Cancer in Lyon, France.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed2000

Metabolism of gamma-hexachlorocyclohexane by Arthrobacter citreus strain BI-100: Identification of metabolites.

Growth characteristics of the aerobic bacterial strain Arthrobacter citreus BI-100 in mineral salts medium with gamma-hexachlorocyclohexane (gamma-HCH) as the sole source of carbon and degradation of gamma-HCH by the strain are reported. The highest yield of the bacteria is observed at a gamma-HCH concentration of 100 mg/L. At this concentration, the bacteria entered the exponential phase of growth without any lag. At 8 h of growth, no residual HCH, but its metabolites, was detectable in the medium. The bacterium attained its stationary phase at 48 h and at 72 h; no metabolite of gamma-HCH could be detected by gas chromatography. Six metabolic intermediates of gamma-HCH produced by A. citreus BI-100 at different periods of growth were characterized by using gas chromatography-mass spectrometry and high-performance liquid chromatography, which furnished evidence for the presence of gamma-1,3,4,5,6-pentachlorocyclohexene, tetrachlorocyclohexene, trichlorocyclohexa-diene, 2-chlorophenol, phenol, and catechol, among others.

Journal Article↗
PubMed1990

Dissimilation of 2,4-dichlorophenoxyacetic acid by Azotobacter chroococcum.

1. A strain of Azotobacter chroococcum which could use 2,4-dichlorophenoxyacetic acid (2,4-D) as sole carbon source was isolated. 2. The strain metabolized 2,4-D via p-chlorophenoxyacetic acid, p-chlorophenol and 4-chlorocatechol; the last metabolite was cleaved by catechol 1,2-dioxygenase. 3. The enzyme exhibited broad substrate specificity.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1994

Comparative metabolism of the renal carcinogen 1,4-dichlorobenzene in rat: identification and quantitation of novel metabolites.

1. The metabolism of 1,4-dichlorobenzene has been studied in the male and female Fisher 344 rat over 72 h after oral administration of 14C-1,4-dichlorobenzene (900 mg = 96.8 microCi/kg). No covalent binding of radioactivity could be detected in samples of liver, kidney, lung and spleen. The major route of excretion was with urine accounting for 41.3% of the dose for male and 37.8% of the dose for female rat within 72 h after dosing. 2. Urinary metabolites of 1,4-dichlorobenzene were identified and quantified. The major metabolites identified in the urine of both the male and female rat, were the sulphate and glucuronide of 2,5-dichlorophenol. Minor amounts of 2,5-dichlorohydroquinone were excreted as an unidentified conjugate. 3. 2-(N-acetyl-cysteine-S-yl)-1,4-dichlorobenzene and 2-(N-acetyl-cysteine-S-yl)-2,3-dihydro-3-hydroxy-1,3-hydroxy-1,4-dich lorobenzen e were minor metabolites excreted in the urine of both sexes. 4. A novel biotransformation pathway for 1,4-dichlorobenzene may be postulated, leading to the urinary excretion of a mercapturic acid of chlorophenol. 5. No marked differences in the distribution and excretion of metabolites of 1,4-dichlorobenzene were observed between the male and female Fisher 344 rat.

Acetylcysteine↗
PubMed1996

1H and 19F-nmr spectroscopic studies on the metabolism and urinary excretion of mono- and disubstituted phenols in the rat.

1. 1H and 19F-nmr spectroscopy was used to investigate quantitatively the urinary excretion of the metabolites of 15 substituted phenols in the rat. The compounds studied were: 2-, 3-, and 4-fluorophenols; 2-, 3-, and 4-trifluoromethylphenol; 2,4-, 2,6- and 3,4-difluorophenol; 2-fluoro-5-trifluoromethylphenol, 3-fluoro-5-trifluoromethylphenol, 2-trifluoromethyl-4-fluorophenol; 3-chloro-4-fluorophenol, 3-fluoro-4-chlorophenol, and 3-methyl-4-fluorophenol. All compounds were dosed to the Sprague-Dawley rat (10 mg/kg i.p.) and urine was collected over the periods 0-8, 8-24 and 24-48 h post-dosing and analyzed using nmr spectroscopy. 2. The compounds were excreted in the urine mainly as glucuronide or sulphate conjugates or as the unchanged parent compound. There was considerable variation in the urinary excretion of the compounds over 48 h ranging from 22.1 to 93.6% of the dose. There was no apparent relationship between the molecular weight of compounds or their metabolites and the percentage molar recovery of each in the urine. 3. Ortho-substituted phenols in general showed a greater propensity for glucuronidation than did either meta- or para-substituted compounds, irrespective of the substituent group. The molar glucuronide-to-sulphate ratio for ortho-substituted compounds was found to be 2.2 +/- 0.9 whereas the ratio for both meta- and para-substituted compounds was 0.8 +/- 0.2 (p < 0.0001). 4. There were characteristic substituent effects of phenolic glucuronidation or sulphation on the 19F-nmr chemical shifts for both F- and CF3-substituted phemols and these substituent effects were a useful aid to metabolite signal assignment. 5. These studies show that nmr spectroscopy provides a rapid and convenient approach to the construction of metabolic databases of simple xenobiotics for the investigation of structure-metabolism relationships.

Animals↗
PubMed1988

Risk of non-Hodgkin's lymphoma among men occupationally exposed to organic solvents.

An occupational history of exposure to organic solvents, defined as daily occupational exposure for at least one year, was more common among 167 men with newly diagnosed non-Hodgkin's lymphoma than among 130 healthy referents from the general population (38 versus 14%). Categorization in five-year age groups gave 3.3 as a Mantel-Haenszel estimate of the odds ratio (95% CI 1.9-5.8). The odds ratio was 6.5 (95% CI 3.2-13.3) for localized supradiaphragmatic tumors and 2.3 (95% CI 1.3-4.3) for other lymphoma presentations. In a logistic model including age and organic solvent, phenoxy acid, and chlorophenol exposure, it could be shown that solvent exposure was an independent risk factor and that no important interaction occurred between the risk factors. With increasing duration of exposure there was a significantly increased risk of lymphoma, a finding implying a dose-response relationship. There was no significant difference in tumor histology between the exposed and unexposed patients. These findings support the concept that occupational exposure to organic solvents is a risk factor for non-Hodgkin's lymphoma. The results also confirm a strong association between such exposure and an initial supradiaphragmatic location of the lymphomas.

Adult↗
PubMed1985

Formaldehyde exposure and respiratory and related cancers. A case-referent study among Finnish woodworkers.

A case-referent study was undertaken to investigate the associations between formaldehyde exposure and respiratory and related cancers. Fifty-seven such cancers from a retrospective cohort of male woodworkers formed the case group. They were matched by year of birth with 171 referents. Exposure to formaldehyde was assessed with job-exposure matrices. The median of the time-weighted average concentration was about 1 ppm, and the mean duration of exposure was 10 years among the exposed. Odds ratios (OR) were calculated for formaldehyde exposure (1.44), peak exposure to formaldehyde (1.26), and exposure to formaldehyde-containing wood dust (1.22). None of the values exceeded unity with statistical significance. Allowance was also made for a 10-year period from the onset of exposure. Birth year, cigarette smoking and exposure to wood dust, chlorophenols, pesticides, and terpenes were controlled by stratification. The adjusted ORs did not change appreciably. The highest OR was 1.95 for formaldehyde exposure without allowance for minimum latency, adjusted for exposure to terpenes. No exposure-response relation was observed for the level, duration, or dose (ppm-years) of formaldehyde exposure. The result is nonpositive and may be explained by absence of effect, by too short a follow-up, or by insufficient power for detecting a mild excess risk.

Adult↗
PubMed2004

Transvalencin A, a thiazolidine zinc complex antibiotic produced by a clinical isolate of Nocardia transvalensis. II. Structure elucidation.

A novel antifungal antibiotic, transvalencin A, is produced by Nocardia transvalensis IFM 10065 isolated from a patient with actinomycotic mycetoma in Japan. The antibiotic structure was elucidated using NMR, mass spectrometric investigations, and X-ray crystallographic analysis. Transvalencin A is a 1:1 complex of a zinc and an organic acid with a phenolic substituent. Transvalencin A is comprised of o-substituted p-chlorophenol, tetrasubstituted oxazoline, disubstituted thiazolyl-N-methylthiazolidine and monosubstituted N-methylthiazolidine.

Anti-Bacterial Agents↗
PubMed1998

Validation of analytical methods and laboratory procedures for chemical measurements.

Method validation is a key element in the establishment of reference methods and in the assessment of a laboratory's competence in producing reliable analytical data. Hence, the scope of the term "method validation" is wide, especially if one bears in mind the role of Quality Assurance/Quality Control (QA/QC). The paper puts validation in the context of the process generating chemical information, introduces basic performance parameters included in the validation processes, and evaluates current approaches to the problem. Two cases are presented in more detail: the development of European standard for chlorophenols and its validation by a full scale collaborative trial and the intralaboratory validation of a method for ethylenethiourea by using alternative analytical techniques.

Chemistry Techniques, Analytical↗
PubMed1999

Environmental health in the east Baltic region--pesticides and persistent organic compounds.

Exposure to, and the potential effects of, pesticides and persistent organic pollutants in the East Baltic region are reviewed. Exposure of the average population to chlorinated compounds seems lower than in most of western Europe, and current pesticide use is very low. However, due to infrastructure failures and poor management controls, industrial hot spots and inadequate storage sites exist that cause high risks to small population fractions. The low exposure of the general population is indicated by low concentrations of polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls in milk fat. Chlorophenol concentrations are also generally lower than in Scandinavia. Some organic pesticides have been found at higher concentrations in Baltic countries and the St. Petersburg area than in Norway, but the range is roughly similar to that in central Europe. Thus the overall risk caused by pesticide residues and persistent organic compounds in the Baltic countries and northwestern Russia is low, but local sites of concern exist.

Baltic States↗
PubMed1999

[Diet as a source of human exposure to polychlorinated dibenzo-P-dioxins (PCDD)].

Dioxins are highly toxic by-products of many industrial processes e.g. chemical and municipal waste incineration or production of chlorophenols. These compounds penetrate the environment via air, water and soil and are then incorporated in food chains. The major source of human exposure (90% of total exposition) is consumption of a wide variety of common foods (meat, fish and dairy products) containing small amounts of dioxins. The average daily intake of PCDD via food was estimated in the range of 1-3 pg/kg bw. Common characteristics of all congeners detected in foodstuffs were 2,3,7,8-chlorine substitution. Commercial milk samples could be contaminated by PCDD/DFs present in the pulp used for the production of the milk cartoon. Also higher levels of these xenobiotics were found in samples from cows grazing in the vicinity of incinerators as compared to samples from rural farms. Human exposure to dioxin begins early in life since breast-feeding is the best way to nourish an infant. The nursing baby in developed countries get a particularly high dose of dioxins (about 85 pg TEQ/kg bw/day). Food contamination with dioxins leads to enhanced accumulation of these compounds in human tissues to the extent of exceeding acceptable level.

Diet↗