[Fatal DNOC (dinitrocresol) poisoning].
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Child, Preschool↗
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Surface-enhanced resonance Raman spectroscopy as an ancillary high-performance liquid chromatography detector for nitrophenol compounds.
In this study, the potential application of surface-enhanced resonance Raman scattering (SERRS) spectroscopy as an off-line secondary detector for HPLC has been evaluated. Four nitrophenol compounds, 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, and 4,6-dinitrocresol were separated by isocratic reverse-phase high-performance liquid chromatography (RP-HPLC) and monitored with a conventional UV detector. Resonance Raman (RR) and SERRS spectroscopy were next used to provide the required specificity for distinguishing the nitrophenol compounds. The SERRS detection limit for both 2-nitrophenol and 4-nitrophenol was calculated to be 14 ppb and that for 2,4-dinitrophenol and 4,6-dinitrocresol was estimated to lie near the parts-per-billion level as well. This detection limit is 2-3 orders of magnitude lower than that obtained by RR spectroscopy.
Chromatography, High Pressure Liquid↗
Biological monitoring of occupational pesticides exposure.
Two kinds of measurement: (1) enzyme activities in blood, and (2) unchanged pesticides and their metabolites in urine or blood have been used in biological monitoring for assessing exposure to pesticides. The assays of acetylcholinesterase (AChE) activity in whole blood and erythrocytes are mainly applied to estimate inhibition by organophosphates (OPs) and carbamates. A level at 70% of an individual's baseline or of a mean population AChE activity has been recommended as a reference value for exposure control. The measurement of lymphocyte "neuropathy target esterase (NTE)" activity in subjects handling axonopathic OPs is mainly for research application. Analytical methods are available for detecting alkylphosphates, carbamates, pyrethroids, chlorinated hydrocarbons, some herbicides and fungicides, chlordimeform, chlorobenzilate, dichloropropene, dinitrocresol and pentochlorophenol or their metabolites in urine or blood. However, due to lack of significant dose-response or dose-effect relationship, the majority of these determinants can only be used as biological exposure indicators to confirm exposure or to estimate internal dose. Further research in developing adequate indicators and methods for biological monitoring of occupational pesticides exposure is needed. Pre-exposure value and/or reference value of relevant indicators are necessary for assessing the degree of exposure and absorption.
Environmental Monitoring↗
Urine profile analysis by field desorption mass spectrometry, a technique for detecting metabolites of xenobiotics. Application to 3,5-dinitro-2-hydroxytoluene.
A technique for the detection of biotransformation products of xenobiotics in crude urine extracts by field desorption mass spectrometric profile analysis is described. The method comprises determination of peak profiles of a series of blank and test samples using low resolution field desorption mass spectrometry, comparison of averaged peak profiles and noise reduction by means of Fisher and ratio weighting of peak intensities. Application of the technique to 3,5-dinitro-2-hydroxytoluene has resulted in the detection of two hitherto unknown metabolites in rat urine. By thin-layer co-chromatography, high resolution electron impact mass spectrometry and thin-layer chromatographic/field desorption mass spectrometric analysis they could be identified as 3,5-dinitro-2-hydroxybenzenemethanol and 3,5-diacetamido-2-hydroxytoluene.
Animals↗
The effects of five weeks treatment with dinitro-o-cresol- or trifluralin-containing pesticides on the germ cells of male mice.
The effects of two pesticides, the insecticide-herbicide Krezonit E, which contains 50% dinitro-o-cresol, and the herbicide Olitref, which contains 26% trifluralin (2,6-dinitro-N,N-dipropyl-4-trifluoromethylaniline), on the gonads and germ cells of male mice were studied. The pesticides were given twice a week for 5 weeks in i.p. doses of 0.6 mg kg-1 for Krezonit E and 6.0 mg kg-1 for Olitref. These doses are 1% of the i.p. LD50. Cytogenic analysis of germ cells carried out from 3 weeks onwards after the last treatment day showed that Olitref significantly increased the frequency of germinal chromosomal abnormalities at 6-7 weeks after treatment. This pesticide increased the frequency of autosomal univalents X/Y separations at meiotic metaphase and multivalent configurations. Krezonit E did not increase significantly the number of chromosomal abnormalities, although there was some increase at 3 weeks, mainly in the form of autosomal univalents.
Animals↗
Toxic effects, at three pH levels, of two reference molecules on common carp embryo.
Early life-stage survival, motility, and growth toxicity tests were carried out on common carp (Cyprinus carpio L.) endotrophic embryo, with two reference molecules (captafol and DNOC), from fertilization to the end of the first two-thirds period of mortalities by starvation. Thirteen days duration exposure was performed in daily renewed medium, at 24.5 degrees C, in standard synthetic water, at three pHs (6.9, 7.8, 9.0), in the presence of 10 mM/liter nontoxic pH buffer. Nominal concentrations of toxicants were 0.0, 0.25, 0.5, 1.0, and 2.0 mg/liter. Toxic effects on survival, motility, and growth decreased with increasing pH. From pH 6.9 to 9.0, the "no-observed-effect concentrations" differed by a factor greater than 8. Motility and growth cannot be considered, at population level, as true sublethal embryo-larval toxicity criteria. The toxicological interpretation of these results is discussed. They confirm the need of multifactorial methods for toxic risks and effects assessment on fish early life stages in the environment.
Animals↗
Mutagenicity of DNOC in Drosophila melanogaster.
The insecticide/ascaricide dinitro-ortho-cresol (DNOC) was tested for mutagenicity in BASC or Muller-5 test with Drosophila melanogaster. The frequencies of induced sexlinked recessive lethals in premeiotic and postmeiotic germ cell stages of spermatogenesis were determined after exposure of adult wild-type males by oral application of DNOC. Sex-linked recessive lethals were scored in the F2 generation according to standard procedures. The mutagenic activity of DNOC at concentrations of 0.25 to 1.01 mM (50-200 ppm) in postmeiotic germ cell stages (11 lethals/1570 chromosomes tested = 0.70%) > premeiotic stages (3/1001 = 0.29%). The mutations rate in all germ cell stages was 0.59% (18/3140). The lowest effective concentration for the induction of recessive lethals in nature sperm was 0.25 mM which is 1/3 to 1/2 LD50 which is approximately 0.61 mM. The frequency of spontaneously occurring lethality was 0.06 (1/1718). The data presented here show significant differences in Kastenbaum-Bowman test. Dimethylnitrosamine (6.8 mM = 500 ppm) induced a rate of 21.0% of lethals (112/534).
Animals↗
Biodegradation of the pesticide 4,6-dinitro-ortho-cresol by microorganisms in batch cultures and in fixed-bed column reactors.
A mixed culture of microorganisms able to utilize 4,6-dinitro-ortho-cresol (DNOC) as the sole source of carbon, nitrogen and energy was isolated from soil contaminated with pesticides and from activated sludge. DNOC was decomposed aerobically in batch cultures as well as in fixed-bed column reactors. Between 65% and 84% of the substrate nitrogen was released as nitrate into the medium, and 61% of the carbon from uniformly 14C-labelled DNOC was recovered as 14CO2. The mixed microbial culture also decomposed 4-nitrophenol and 2,4-dinitrophenol but not 2,3-dinitrophenol, 2,6-dinitrophenol, 2,4-dinitrotoluene, 2,4-dinitrobenzoic acid or 2-sec-butyl-4,6-dinitrophenol (Dinoseb). Maximal degradation rates for DNOC by the bacterial biofilm immobilized on glass beads in fixed-bed column reactors were 30 mmol day-1 (1 reactor volume)-1, leaving an effluent concentration of less than 5 micrograms l-1 DNOC in the outflowing medium. The apparent Ks value of the immobilized mixed culture for DNOC was 17 microM. Degradation was inhibited at DNOC concentrations above 30 microM and it ceased at 340 microM, possibly because of the uncoupling action of the nitroaromatic compound on the cellular energy-transducing mechanism.
2,4-Dinitrophenol↗
The metabolism and viability of the canine heart during hypothermic (4 degrees C) asanguinous perfusion for 72-96 hr.
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Animals↗
Metabolic studies of isolated canine hearts perfused at 4 degree C for up to 96 hours, with assessment of viability.
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Animals↗
The relationship between uncoupling of oxidative phosphorylation and neuronal necrosis within the CNS in rats dosed with trihalogenated imidazoles.
The trihalogenated imidazoles, trichloroimidazole (TCI), tribromoimidazole (TBI), and triiodoimidazole (TII), are in vitro uncouplers of oxidative phosphorylation with similar activities. Although TCI and TBI are also uncouplers in vivo, some doubt exists for TII, which is much less toxic and produces atypical signs of poisoning. Dibromo- and monobromoimidazole do not uncouple oxidative phosphorylation either in vitro or in vivo. Dosing of TCI and TBI to rats resulted within 24-48 hr in neuronal necrosis within the CNS involving the vestibular nucleus, red nucleus, and outer parietal neocortex and ataxia of the hindlimbs. However, no neuronal necrosis or ataxia was observed after dosing of TII to rats, even when given at doses four times greater than for either TCI or TBI, resulting in much higher brain concentrations. Although TBI was equitoxic to rats, mice, hamsters, and gerbils, CNS damage and ataxia were observed only in the rat, even though comparable brain concentrations of TBI were found in the gerbil. Measurement of the concentration of TBI in the dissected rat brain gave no indication of localized concentrations of compound in the areas associated with neuronal damage. Doses of TBI and the classical uncoupler 3,5-dinitro-o-cresol (DNOC), matched for whole body O2 consumption, caused comparable changes in rat brain blood flow although DNOC does not cause brain damage. Changes in blood flow were not restricted to those brain areas susceptible to damage. Thus, although we were unable to completely dissociate CNS damage from uncoupling of oxidative phosphorylation produced by TBI and TCI in the rat, it is unlikely that such damage is primarily related to the uncoupling ability of these compounds.
Animals↗
The teratogenic and mutagenic effects of dinitro-o-cresol-containing herbicide on the laboratory mouse.
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Animals↗
Additional data on the mutagenic effect of dinitro-o-cresol-containing herbicides.
In in vivo experiments in mice it was studied, on the one hand, whether 1 year after treatment with dinitro-o-cresol (DNOC)-containing herbicide it was possible to detect any increase in chromosome aberrations in the bone marrow cells of the mouse, and on the other hand, to learn the frequency of chromosome aberrations in the subsequent generations when the treatment of the male animals with DNOC-containing herbicide was continued in each generation and when it was discontinued before mating. The chromosome aberrations of the bone marrow cells of the treated mice were demonstrated even 1 year after the treatment. After the treatment of the male animals was continued in each subsequent generation, the chromosome aberrations in the embryos increased, whereas when it was discontinued, it decreased in the subsequent generations.
Animals↗
Induction of biotransformation in the liver of Eel (Anguilla anguilla L.) by sublethal exposure to dinitro-o-cresol: an ultrastructural and biochemical study.
Structural and functional alterations in hepatocytes of the European eel, Anguilla anguilla, following a 4-week-exposure to 5, 50, and 250 micrograms/liter dinitro-o-cresol (DNOC) were investigated by means of electron microscopy and biochemistry and compared to liver pathology in eels exposed to the chemical spill into the Rhine river at Basle in November 1986. Whereas phenological parameters (growth, condition factor) are unaffected, ultrastructural and biochemical alterations are detectable at greater than or equal to 50 and 5 micrograms/liter DNOC, respectively. Structural modifications include: rounding-up of the nuclei; fractionation and reduction of the rough endoplasmic reticulum; proliferation of the smooth endoplasmic reticulum (SER), mitochondria, peroxisomes, and lysosomes; bundles of rod-shaped SER profiles; annulate lamellae; membrane whorls within mitochondria; crystallization of the peroxisomal matrix and glycogen bodies; glycogen depletion and lipid augmentation. Structural changes can be correlated to an increase in hepatic lipid and protein contents as well as stimulation of mitochondrial (cytochrome c oxidase), peroxisomal (catalase, allantoinase, uricase), lysosomal (arylsulfatase), and microsomal (esterase) enzymes. An increase in NADPH-cytochrome c reductase and cytochrome P450 as well as UDP-glucuronyltransferase and arylsulfotransferase activities in the microsomal fraction document an induction of hepatic biotransformation as a functional correlate to SER proliferation. Maximum inducibility of biotransformation enzymes at 50 micrograms/liter indicates a biphasic, concentration-dependent reaction of eel liver. Comparison of DNOC-induced effects with liver pathology in eel exposed to the chemical spill in 1986 reveals striking similarities so that DNOC may not be excluded as a possible factor in the fish kill in the Rhine river.
Animals↗
Effect of DNOC, Ferbam and Imidan exposure on mouse sperm morphology.
DNOC, Ferbam and Imidan were tested in (C3H X C57BL/6) F1 mice to assess their potential testicular toxicity. Chemicals were administered i.p. and per os at different doses for 5 consecutive days. After 35 days the testicular was toxicity was evaluated by measuring the testicular weights, the sperm counts and the percentage of abnormal sperm. DNOC and Imidan failed to induce teratospermia in mice treated by both routes of administration. Conversely Ferbam induced a statistically significant increase in teratospermia only following per os administration to mice at a dose of 1000 mg/kg b.w./day. These data indicate that per os administration of Ferbam succeeded in producing active metabolites able to interfere with the differentiation process of spermatogenic cells.
Administration, Oral↗
Genetic safety evaluation of pesticides in different short-term tests.
Cyanazine, cyhexatin, dicamba and DNOC are pesticides commonly and broadly used in agriculture pest control. However, there is little information on their toxicity and mutagenicity in human cells and in whole animals. Therefore, UDS assay and SCE assay in human peripheral lymphocytes, and chromosome aberration analysis in bone marrow of rats have been used to assess the DNA-damaging activity of the above pesticides. Cyanazine proved non-genotoxic in all the test systems. Cyhexatin showed only weakly positive results for SCE induction in human lymphocytes, providing no concern for genotoxicological hazard. While dicamba did not show clastogenic effects in rodents, DNOC gave significant dose-related increases of structural chromosome aberrations in rat bone marrow cells. Female animals showed increased sensitivity to the toxic effects by DNOC at the highest dose. The results provide further information on the intrinsic genotoxic activity of the tested pesticides, which may contribute to the toxicological assessment of the risk associated with human exposure.
Animals↗
Nitroreductase reactions of Arabidopsis thaliana thioredoxin reductase.
Arabidopsis thaliana NADPH:thioredoxin reductase (TR, EC 1.6.4.5) catalyzed redox cycling of aromatic nitrocompounds, including the explosives 2,4,6-trinitrotoluene and tetryl, and the herbicide 3,5-dinitro-o-cresol. The yield of nitro anion radicals was equal to 70-90%. Redox cycling of tetryl was accompanied by formation of N-methylpicramide. Bimolecular rate constants of nitroaromatic reduction (kcat/Km) and reaction catalytic constants (kcat) increased upon an increase in oxidant single-electron reduction potential (E(1)7). Using compounds with an unknown E(1)7 value, the reactivity of TR increased parallelly to the increase in reactivity of ferredoxin:NADP+ reductase of Anabaena PCC 7119 (EC 1.18.1.2). This indicated that the main factor determining reactivity of nitroaromatics towards TR was their energetics of single-electron reduction. Incubation of reduced TR in the presence of tetryl or 2,4-dinitrochlorobenzene resulted in a loss of thioredoxin reductase activity, most probably due to modification of reduced catalytic disulfide, whereas nitroreductase reaction rates were unchanged. This means that on the analogy of quinone reduction by TR (D. Bironaite, Z. Anusevicius, J.-P. Jacquot, N. Cenas, Biochim. Biophys. Acta 1383 (1998) 82-92), FAD and not catalytic disulfide of TR was responsible for the reduction of nitroaromatics. Tetryl, 2,4,6-trinitrotoluene and thioredoxin increased the FAD fluorescence intensity of TR. This finding suggests that nitroaromatics may bind close to the thioredoxin-binding site at the catalytic disulfide domain of TR, and induce a conformational change of enzymes (S.B. Mulrooney, C.H. Williams Jr., Protein Sci. 6 (1997) 2188-2195). Our data indicate that certain nitroaromatic herbicides, explosives and other classes of xenobiotics may interfere with the reduction of thioredoxin by plant TR, and confer prooxidant properties to this antioxidant enzyme.
Aniline Compounds↗
Resistance to nitrophenolic herbicides and metronidazole in the cyanobacterium Synechocystis sp. PCC 6803 as a result of the inactivation of a nitroreductase-like protein encoded by drgA gene.
Dinoseb is a herbicide known to inhibit photosystem II electron transfer like DCMU, triazine and phenolic-type herbicides. The mutant Din7 of the cyanobacterium Synechocystis sp. PCC 6803, selected for resistance to dinoseb, and the mutant Ins2, constructed by the insertion of the kanamycin resistance cassette into the drgA gene, were cross-resistant to other nitrophenolic herbicides (DNOC, 2,4-dinitrophenol) and to the cell inhibitor metronidazole but not to the photosystem II inhibitors DCMU or ioxynil. The Din7 mutant had the same characteristics of photosystem II inhibition by dinoseb as the wild type. This result suggested the existence of another site for dinoseb inhibition. The wild type cells modified dinoseb to a non-toxic product that gave an absorption spectrum similar to that of dithionite treated dinoseb containing reduced nitro groups. In contrast, the Din7 mutant did not modify dinoseb. These phenomena were controlled by the drgA gene encoding a protein which showed similarity to several enzymes having nitroreductase activity. The addition of superoxide dismutase to the medium relieved the toxic effect of dinoseb in wild type cells but not in Din7. It is proposed that in wild type cells of Synechocystis sp. PCC 6803 the DrgA protein is involved in detoxification of dinoseb via the reduction of the nitro group(s) and this process is accompanied by the formation of toxic superoxide anions. Mutations blocking the activity of the DrgA protein lead to the development of resistance to nitrophenolic herbicides and metronidazole.
2,4-Dinitrophenol↗