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Soft tissue sarcoma and non-Hodgkin's lymphoma in relation to phenoxyherbicide and chlorinated phenol exposure in western Washington.

A population-based case-control study was conducted in western Washington State to evaluate the relationship between occupational exposure of men aged 20-79 to phenoxyacetic acid herbicides and chlorinated phenols and the risks of developing soft tissue sarcoma (STS) and non-Hodgkin's lymphoma (NHL). Occupational histories and other data were obtained by personal interviews for 128 STS cases and 576 NHL cases, diagnosed between 1981 and 1984, and for 694 randomly selected controls without cancer. Among the study subjects with any past occupational exposure to phenoxyherbicides, the estimated relative risk and 95% confidence interval of developing STS was 0.80 (0.5-1.2), and of developing NHL, 1.07 (0.8-1.4). Risk estimates of developing STS and NHL associated with past chlorophenol exposure were 0.99 (0.7-1.5) and 0.99 (0.8-1.2), respectively. No increasing risk of either cancer was associated with overall duration or intensity of chemical exposure or with exposure to any specific phenoxyherbicide per se. However, estimated risks of NHL were elevated among men who had been farmers, 1.33 (1.03-1.7), forestry herbicide applicators, 4.80 (1.2-19.4), and for those potentially exposed to phenoxyherbicides in any occupation for 15 years or more during the period prior to 15 years before cancer diagnosis, 1.71 (1.04-2.8). Increased risks of NHL were also observed among those with occupational exposure to organochlorine insecticides, such as DDT [1.82 (1.04-3.2)] and organic solvents [1.35 (1.06-1.7)], and to other chemicals typically encountered in the agricultural, forestry, or wood products industries. These results demonstrate small but significantly increased risks of developing NHL in association with some occupational activities where phenoxyherbicides have been used in combination with other types of chemicals, particularly for prolonged periods. They do not demonstrate a positive association between increased cancer risks and exposure to any specific phenoxyherbicide product alone. Moreover, these findings provide no evidence of increased risks of developing NHL associated with chlorinated phenol exposure or of developing STS associated with exposure to either class of chemical.

Adult↗

Ability of several hexachlorobenzene metabolites to decrease rat-liver porphyrinogen carboxy-lyase and to produce porphyrin accumulation in chick-embryo liver.

Since hexachlorobenzene (HCB) action seems to be mediated through its metabolites, this study aimed to identify the metabolites and account for the HCB action by evaluating the ability of several of them to inhibit normal rat-liver porphyrinogen carboxy-lyase in vitro and to produce porphyrin accumulation in chick-embryo liver in ovo. Only three of the 11 metabolites assayed produced significant inhibitory effects at 10(-3) M concentration, the order being tetrachlorohydroquinone greater than pentachlorophenol much greater than pentachlorothiophenol. At concentrations below 10(-4) M tetrachlorohydroquinone did not inhibit the enzyme. Most of the metabolites assayed produced porphyrin accumulation, in the following order of strength: chlorophenols greater than chlorothiophenols greater than chlorobenzenes. Phenolic metabolites, therefore, not only produce the greatest amounts of porphyrin accumulation in the liver of the chick embryo but are also the strongest of the metabolite inhibitors of porphyrinogen carboxy-lyase in rat liver. It is possible that they decrease enzymatic activity by binding to the enzyme. This paper discusses the implications of these results for the mechanism of HCB porphyria induction.

Animals↗

The influence of ascorbic acid on the hepatic cytochrome P-450, and glutathione in guinea-pigs exposed to 2,4-dichlorophenol.

Chlorophenols, mainly used as biocides, are compounds with a wide spectrum of toxic effects including teratogenic and carcinogenic actions. In this study, the effects of 2,4-dichlorophenol (2,4-DCP) on hepatic microsomal cytochrome P-450, NADPH-cytochrome c reductase activity, liver ascorbic acid (AA) and glutathione (GSH) content were studied in guinea-pigs with a low (2 mg/day/animal) or a high (50 mg/day/animal) ascorbic acid intake. The high AA intake significantly increased liver AA and GSH levels. There was a clear-cut correlation between liver AA and GSH levels. Administration of 2,4-DCP significantly decreased cytochrome P-450 and NADPH-cytochrome c reductase activity in hepatic microsomes isolated from guinea-pigs with the low AA intake. Such a reduction was not observed in intoxicated guinea-pigs with the high AA intake. The results suggest that AA can play a protective role in 2,4-DCP toxicity.

Animals↗

On-line monitoring by membrane introduction mass spectrometry of chlorination of organics in water. Mechanistic and kinetic aspects of chloroform formation.

Chloroform formation during the chlorination of simple organic molecules modeling humic substances, such as phenol and di- and trihydroxybenzenes, was studied by on-line membrane introduction mass spectrometry (MIMS). Under the reaction conditions employed, chloroform was rapidly formed from 1,3-dihydroxybenzene, 1, 4-dihydroxybenzene, phenol and 1,2,3-trihydroxybenzene with yields of 17, 13, 7 and 5%, respectively. With the exception of aniline, which afforded a 17% chloroform yield, non-phenolic compounds, such as nitrobenzene, chlorobenzene, toluene, benzene and cyclohexanol, furnished low yields. Mechanistic studies showed that phenol is chlorinated consecutively and produces initially chlorophenol. It is suggested that chloroform might be formed mainly from chlorinated 3, 5-cyclohexadienone-type intermediates. MIMS was also used to determine the reaction rates and to study the kinetics of the chlorination. A good Hammett linear correlation for an electrophilic substitution mechanism was found for the compounds C(6)H(5)X (X = NH(2), OH, CH(3), H, Cl and NO(2)).

Chloroform↗

Cancer mortality among rice growers in Novara Province, northern Italy.

Some excess of non-Hodgkin lymphomas (NHL) and soft tissue sarcomas (STS) was reported in the literature among agricultural workers, mainly in relation to exposure to phenoxyacids and chlorophenols. In this study, information was analyzed for a cohort of rice growers that comprised 1,493 subjects, and for a follow-up that was more than 99% complete with regard to both traced subjects and known causes of deaths. A total of 960 subjects (65%) died during the observation period (1957-1992). Lower than expected standardized mortality ratios (SMRs) were found for all causes, for cardiovascular diseases (especially ischemic heart disease) and for all cancers. Slightly increased SMRs were found for some cancer sites (oral cavity, esophagus, liver, intestines, pancreas, bladder, STS, and NHL), although none of these was statistically significant in the overall analysis. An excess risk of close to statistical significance was found for NHL among workers with longer exposure during the period when phenoxyacid herbicide was in use (1950-1992). Thus, a prolonged follow-up is advisable. At present the study should be evaluated in the context of the data set suggesting a tendency toward an increased risk of NHL among farmers.

Adult↗

Photosensitization of crystalline and amorphous titanium dioxide by platinum(IV) chloride surface complexes.

Anatase, rutile, and amorphous titania powders were surface-modified by grinding with PtCl4 and H2[PtCl6]. Only the anatase modification afforded hybrid photocatalysts capable of degradation of 4-chlorophenol (4-CP) with visible light, with sufficient stability towards decomplexation. Grinding with K2[PtCl4] produced materials of only low photocatalytic activity. Most efficient photocatalysts contained up to 2 wt% of PtIV. At higher surface loading the excess fraction of the complex is desorbed into the aqueous solution. Scavenging experiments with benzoic acid and tetranitromethane revealed that hydroxyl radicals are produced by the primary reduction of oxygen by conduction band electrons generated through electron injection from a postulated surface platinum(III) complex. It is proposed that the latter is formed from a charge-transfer ligand-to-metal (CTLM) excited state through homolysis of the Pt-Cl bond. Accordingly. the primary oxidation of 4-CP may occur by adsorbed chlorine atoms, the intermediary existence of which was demonstrated by scavenging experiments with phenol.

Journal Article↗

Heterodinuclear cryptates [EuML(dmf)](ClO(4))(2)(M=Ca, Cd, Ni, Zn): tuning the luminescence of europium(III) through the selection of the second metal ion.

Four heterodinuclear cryptates [EuML(dmf)](ClO(4))(2) (M=Ca, Cd, Ni, Zn) were synthesized by a two-step method (L denotes deprotonated anionic cryptand synthesized by condensation of tris(2-aminoethyl)amine with 2,6-diformyl-4-chlorophenol). The ES-MS spectra of the four cryptates and the crystal structure of [EuNiL(dmf)](ClO(4))(2) x MeCN confirm that a strict dinuclear Eu(III)-M(II) entity exits in the cryptates. The cyclic voltammetry and luminescence spectral investigations indicate that the introduction of second metal ions into the mononuclear Eu(III) cryptate result in a negative shift of the redox potential of Eu(III) and a change in luminescence intensity of Eu(III). The cryptate [EuML(dmf)](ClO(4))(2) was shown to quench the emission of Eu(III) when M=Ni and to enhance the emission of Eu(III) when M=Ca, Cd, and Zn in the sequence: mononuclear<Eu-Ca<Eu-Cd<Eu-Zn.

Europium↗

The effects of NaCl and some heavy metals on the denitrification activity of Ochrobactrum anthropi.

Ochrobactrum anthropi is a well-known Gram-negative bacterium, with the ability to degrade atrazine, urea-formaldehyde and chlorophenols. Investigation were made of the nitrate and nitrite reduction capacities of the strain in succinate and glucose media, and the tolerance of its denitrification to NaCl and some heavy metals. Succinate proved to be a better carbon source to drive denitrification by O. anthropi. Batch fermentation studies in anaerobic succinate medium indicated reduction capacities of 85.4 +/- 9.1 and 48.6 +/- 5.2 mgh(-1)g(-1) dry cell for NO(3) (-) and NO(2) (-), respectively. The nitrite accumulation of the cells revealed that O. anthropi is a group C denitrifying bacterium. Its growth in DSM 1 broth containing NaCl up to 40 g l(-1) demonstrates that O. anthropi belongs in the group of moderately halophilic bacteria. Despite the fact that 42.5 g NaCl l(-1) caused 50% growth inhibition in DSM 1 broth, the cells in the stationary phase readily tolerated NaCl concentrations up to 100 g l(-1). Complete denitrification was achieved in test media containing 30 g NaCl l(-1) after 1 week and the nitrate reductase retained its activity up to 100 g NaCl l(-1). The cells were tolerant to Hg, Zn, Pb, Cu and Ni, and N(2) was producted at tolerated concentrations of the metal in the cases of Hg and Pb.

Culture Media↗

Immunotoxic effects of chemicals: A matrix for occupational and environmental epidemiological studies.

BACKGROUND: Many biological and chemical agents have the capacity to alter the way the immune system functions in human and animals. This study evaluates the immunotoxicity of 20 substances used widely in work environments. METHODS: A systematic literature search on the immunotoxicity of 20 chemicals was performed. The first step was to review literature on immunotoxicity testing and testing schemes adopted for establishing immunotoxicity in humans. The second step consisted of providing a documentation on immunotoxicity of substances that are widely used in work environment, by building tables for each chemical of interest (benzene, trichloroethylene, PAHs, crystalline silica, diesel exhausts, welding fumes, asbestos, styrene, formaldehyde, toluene, vinyl chloride monomer, tetrachloroethylene, chlorophenols, 1,3-butadiene, mineral oils, P-dichlorobenzene, dichloromethane, xylene, 1,1,1-trichloroethane, ethylene oxide). The third step was the classification of substances; an index (strong, intermediate, weak, nil) was assigned on the basis of the evidence of toxicity and type of immunotoxic effects (immunosuppression, autoimmunity, hypersensitivity) on the basis of the immune responses. Finally substances were assigned a score of immunotoxic power. RESULTS: Tables have been produced that include information for the 20 substances of interest, based on 227 animal studies and 94 human studies. Each substance was assigned an index of immunotoxic evidence, a score of immunotoxic power and type of immunotoxic effect. CONCLUSIONS: This matrix can represent a tool to identify chemicals with similar properties concerning the toxicity for the immune system, and to interpret epidemiological studies on immune-related diseases.

Animals↗

Health effects of pesticides: a review of epidemiologic research from the perspective of developing nations.

Acute poisoning among pesticide applicators is still a prominent health hazard in rural areas in developing countries, but published reports are very rare. Registration analysis and descriptive study are helpful in giving guidance for orientation and evaluation of preventive strategies and measures. Data and material from China show that, in circumstances with a well organized grass-roots-level network of primary health care services, poisoning episodes can be prevented through dissemination of information of hazards and provision of prevention training courses. Among pesticide manufacturing workers, especially manual packers of organophosphorus insecticides, there is suggestive evidence of subacute poisoning resulting from continuous low-level exposure. Chronic delayed neuropathy has, rarely, been reported. Further study of the cause of subacute poisoning now requires analytical rather than descriptive investigations. There is still no solid documentation of an association of excess human cancer and the use of chlorinated hydrocarbon insecticides. Phenoxyacetic and chlorophenol herbicides recently have been widely studied for causation of soft tissue sarcoma, non-Hodgkin's leukemia, and lymphoma. Although the evidence at present indicates a positive association, discrepancies in findings and resultant controversy require further study. Epidemiological surveys on the harmful effect of DBCP are quite instructive. Investigations in exposed populations verified and extended the observation in animals as infertility and gender ratio change in the next generation. Adverse reproductive effects of a number of pesticides, particularly birth defects resulting from pesticides (other than those already documented for organomercurials), require further study.

China↗

The mass spectrometry of chlorinated dibenzo-p-dioxins.

All aspects of the use of mass spectrometry for the identification and quantitation of chlorodibenzo-p-dioxins are critically reviewed. The mass spectra obtained by various ionization methods are discussed. Numerous mass spectral techniques and cleanup procedures are covered, with emphasis on their interrelationships. These techniques have been applied to the determination of chlorodibenzo-p-dioxins in many different matrices, including product materials, such as chlorophenols and phenoxy acid herbicides, and toxicological and environmental materials such as cattle, fish, rodent and human tissues. Formation and degradation studies, which include thermal chemistry, photochemistry and chemical stability and degradation, are presented. Numerous considerations in the handling and quantitation of chlorodibenzo-p-dioxins, such as interferences, detection limits and recovery studies, are evaluated.

Adipose Tissue↗

Guest-induced supramolecular isomerism in inclusion complexes of T-shaped host 4,4-bis(4'-hydroxyphenyl)cyclohexanone.

The T-shaped host molecule 4,4-bis(4'-hydroxyphenyl)cyclohexanone (1) has an equatorial phenol group and a cyclohexanone group along the arms and an axial phenol ring as the stem. The equatorial phenyl ring adopts a "shut" or "open" conformation, like a windowpane, depending on the size of the guest (phenol or o/m-cresol), for the rectangular voids of the hydrogen-bonded ladder host framework. The adaptable cavity of host 1 expands to 11x15-18 A through the inclusion of water with the larger cresol and halophenol guests (o-cresol, m-cresol, o-chlorophenol, and m-bromophenol) compared with a size of 10x13 A for phenol and aniline inclusion. The ladder host framework of 1 is chiral (P2(1)) with phenol, whereas the inclusion of isosteric o- and m-fluorophenol results in a novel polar brick-wall assembly (7x11 A voids) as a result of auxiliary C-H...F interactions. The conformational flexibility of strong O-H...O hydrogen-bonding groups (host 1, phenol guest), the role of guest size (phenol versus cresol), and weak but specific intermolecular interactions (herringbone T-motif, C-H...F interactions) drive the crystallization of T-host 1 towards 1D ladder and 2D brick-wall structures, that is, supramolecular isomerism. Host 1 exhibits selectivity for the inclusion of aniline in preference to phenol as confirmed by X-ray diffraction, 1H NMR spectroscopy, and thermogravimetry-infrared (TG-IR) analysis. The T(onset) value (140 degrees C) of aniline in the TGA is higher than those of phenol and the higher-boiling cresol guests (T(onset)=90-110 degrees C) because the former structure has more O-H...N/N-H...O hydrogen bonds than the clathrate of 1 with phenol which has O-H...O hydrogen bonds. Guest-binding selectivity for same-sized phenol/aniline molecules as a result of differences in hydrogen-bonding motifs is a notable property of host 1. Host-guest clathrates of 1 provide an example of spontaneous chirality evolution during crystallization and a two-in-one host-guest crystal (phenol and aniline), and show how weak C-H...F interactions (o- and m-fluorophenol) can change the molecular arrangement in strongly hydrogen-bonded crystal structures.

Crystallography, X-Ray↗

Formation of trichlorinated dibenzo-p-dioxins from 2,4-dichlorophenol and 2,4,5-trichlorophenolate: a theoretical study.

The reaction of the 2,4,5-trichlorophenolate anion with 2,4-dichlorophenol to afford trichlorinated dibenzo-p-dioxins (T3CDDs) is investigated at the B3LYP/6-31+G(d) and B3LYP/6-311+G(3df,2p)//B3LYP/6-31+G(d)+ZPVE(B3LYP/6-31+G(d)) levels of theory. The first stage of the process corresponds to the formation of a predioxin, which can evolve through four different routes. Two of them lead directly to the products 2,3,7-T3CDD and 1,3,8-T3CDD, and the other two afford different predioxin-type intermediates, which in turn can evolve through all or some of the four routes to give new predioxins or T3CDD. Consequently, the theoretical results obtained show plainly the complex chemistry implied in the formation of dioxins from chlorophenols via anionic mechanisms by disclosing all the critical structures through which the system evolves, thus allowing assessment of the viability of the different mechanistic routes and the accessible products. The statistical thermodynamics treatment at 1 atm and 298.15, 600, 900, and 1200 K indicates that at higher temperatures, the Gibbs energy barrier for the formation of the initial predioxin is clearly the rate-determining step for the whole process, but at lower temperatures the Gibbs energy barrier for this step is similar to those for its evolution into 2,3,7-T3CDD. This result is in contrast with previous proposals that the closure of the central ring is the rate-limiting step. Finally, according to our results the rate constant for the formation of polychlorinated dibenzo-p-dioxins increases with the temperature, in agreement with the experimental observation that the conversion of trichlorophenols increases when going from 600 to 900 K in the gas phase in the absence of catalysts, and with DFT molecular dynamics results.

Journal Article↗

Use of a high-throughput umu-microplate test system for rapid detection of genotoxicity produced by mutagenic carcinogens and airborne particulate matter.

In the present study, we developed a rapid umu-microplate test system that uses the nitroreductase- and O-acetyltransferase-overproducing Salmonella typhimurium strain NM3009 and the O-acetyltransferase-overproducing S. typhimurium strain NM2009 to detect genotoxic activity in small volume samples. The assay was used to test the genotoxicity of several standard mutagens and environmental samples. Exponentially growing cultures of NM3009, NM2009, and the parental strain TA1535/pSK1002 were incubated in 96-well microplates with test chemicals both in the presence and in the absence of rat liver S9. The relative beta-galactosidase activities were then determined colorimetrically using either chlorophenol red-beta-D-galactopyranoside (CPRG) or O-nitrophenyl-beta-D-galactopyranoside (ONPG) as a measure of umuC gene induction activity. The sensitivities of NM3009 without S9 mix and NM2009 with S9 mix to nitroarenes and aromatic amines were up to 24- to 75-fold higher than those of the parent strain. Induction of umuC gene expression was detected more readily with CPRG than ONPG. The umu-microplate assay also detected genotoxicity in organic extracts of particulate matter from air samples collected in Osaka City, Japan. The pattern of the responses suggested that the genotoxic activity of the particulate extract was due primarily to nitrated polycyclic aromatic hydrocarbons. Our results indicate that the umu-microplate assay may be a useful way of carrying out rapid screens for genotoxicity in small-volume environmental samples.

Air Pollutants↗

Non-Hodgkin's lymphoma and farming: an expanded case-control study.

A previously published case-control study of agricultural risk factors involved male cases of non-Hodgkin's lymphoma registered under code 202 of the International Classification of Diseases (ICD). This study has been expanded with the inclusion of cases registered under ICD code 200, and additional controls. The expanded study comprises 100 ICD 200 cases and 83 ICD 202 cases registered during the period 1977-81, together with 338 controls selected from other cancer registrations during the same period. The largest relative risk for specific farming types was for orchard workers (odds ratio = 3.7, 90% confidence limits 1.1-12.1). No elevated risks were observed for exposure to farm animals, nor for potential exposure to phenoxy herbicides (odds ratio = 1.0, 90% confidence limits 0.7-1.5), or chlorophenols (odds ratio = 1.4, 90% confidence limits 0.8-2.3). The previous finding of an excess risk associated with fencing work was weakly supported by the expanded study (odds ratio = 1.4, 90% confidence limits 1.0-2.0). However, the previous finding of an excess risk associated with meat works employment was more strongly supported (odds ratio = 1.8, 90% confidence limits 1.2-2.6). One relevant risk factor is 2,4,6-TCP which is used in the treatment of pelts, but the excess risks do not appear to be confined to pelt department workers. An alternative hypothesis is that meat workers may be exposed to oncogenic viruses.

Agricultural Workers' Diseases↗

Sensitivity evaluation of the Daphtoxkit and Thamnotoxkit microbiotests on blind samples.

At the Oregon State University Workshop we utilized two "culture/maintenance-free" microbiotests, the Thamnotoxkit F with the anostracan crustacean Thamnocephalus platyurus and the Daphtoxkit F magna with the cladoceran crustacean Daphnia magna, to determine the toxicity of water samples in a blind format. The Thamnotoxkit was applied to 7 samples and the Daphtoxkit to 12 samples. The chemical composition of the water samples to which the Toxkit microbiotests had been applied was disclosed a posteriori by the organizers and appeared to contain chlordimeform, colchicine, phosdrin, mercuric chloride, sodium arsenite, metham sodium, sodium cyanide, trimethylol propane phosphate, p-chlorophenol and a natural sediment sample containing mercury. Three of the water samples were blanks that had not been spiked with chemicals. No false positives were obtained with the two Toxkits and all the toxic waters were earmarked as such by the microbiotests, except trimethylol propane phosphate, which was not found to induce acute effects in Daphnia magna in the non-diluted water sample containing 100 mg l(-1) of this compound.

Animals↗

Toxicity detection from EILATox-Oregon Workshop samples by using kinetic photobacteria measurement: the Flash method.

The Flash test, which can be used to measure the toxicity from clear, turbid and coloured samples with identical protocol, was used in the EILATox-Oregon Workshop. During the workshop, 17 synthetic samples and three environmental samples were tested. In the Flash method the photobacteria Vibrio fischeri are initially dispensed on top of the sample and the light output of the bioluminescence reaction is recorded at a rate of several readings per second. The change in the light production was measured at two points: 30 s and 30 min after exposure at room temperature. Toxicity calculations were done by using either the peak height of the sample or the peak height of the control sample (maximum signal at 0-2 s). When the peak height of the sample is used as a reference, the colour and turbidity effect of solid particles are taken into account throughout the whole measurement period. In the EILATox-Oregon Workshop toxicity was seen in samples 1 (chlordimeform), 4 (phosdrin), 5 (HgCl(2)), 6 (sodium arsenite), 8 (metham sodium), 12 (p-chlorophenol), 14 (sodium selenite) and 17 (MNNG). Only samples 1, 4 and 12 showed different ec(50) values between different calculations of toxicity. The ec(50) values were calculated and compared with the ec(50) values of Microtox derived from the literature. The Flash test will not replace the standardized photobacteria test, but is the advanced version of it and is needed when the sample matrix is complex and when speed and low costs are required.

Biosensing Techniques↗

Specific determination of bromobenzene metabolites by high-performance liquid chromatography.

A chromatographic method for the quantitative and simultaneous determination of phenolic and mercapturic acid type metabolites of bromobenzene is presented. Acid hydrolysis (1.5 N HCl, 100 degrees C, 10 min) yielded unconjugated bromophenols. After extraction (ethyl acetate, pH 2), evaporation to dryness and dissolution in methanol, samples were analysed by high-performance liquid chromatography (HPLC) with a c18 reverse-phase column and a phosphate buffer (0.1 M,pH 9 + 5 mM tetrabutylammonium dihydrogen phosphate) - acetonitrile gradient with ultraviolet detection (225 nm). Benzylmercapturic acid and o-chlorophenol were used as internal standards. Using this method, it was possible to determine simultaneously o, m- and p-bromophenols together with o-, m- and p-bromophenylmercapturic acids. Additional validation data were obtained by analysis of urine samples from rats treated with bromobenzene. This new method was compared to existing procedures.

Acetylcysteine↗