Toxic Potential (toxic + potential)

Distribution by Scientific Domains

Selected Abstracts

P71 Metabolism of delta-3-Carene by human cytochrom 450 enzymes

Mike Duisken
Occupational exposure to monoterpenes occurs in saw mills, particle-board plants, carpentry shops and other types of wood-treating industries. The bicyclic monoterpene delta-3-Carene, one of the components of turpentine, may irritate the skin and muceous membranes and prolonged exposure may result in allergic contact dermatitis or chronic lung function impairment. The effects of low concentrations of delta-3-Carene on alveolar macrophages in vitro were examined and a dose-dependent relationship between the cell viability and the delta-3-Carene concentration was found. Little is known about the metabolism of delta-3-Carene in mammalians. In order to determine the toxic potential of this monoterpene we studied the human metabolism of delta-3-Carene in vitro. Therefore we used pooled human liver S9 and human liver microsomal cytochrome P450 enzymes. By using GC-MS analysis we found one main metabolite produced at high rates. The structure was identified by its mass spectra. The mass fragmentation indicated hydroxylation in allyl position. After synthesis of the assumed product in a four step reaction, it was characterized as delta-3-Carene-10-ol. There was a clear correlation between the concentration of the metabolite production, incubation time and enzyme concentration, respectively. Kinetic analysis showed that Km and Vmax values for the oxidation of delta-3-Carene by human liver microsomes were 0.39 ,M and 0.2 nmol/min/nmol P450. It is the first time that delta-3-Carene-10-ol is described as human metabolite of delta-3-Carene. [source]

ISTA13-catecholamine toxicity and metabolism in the ciliated protozoan, Tetrahymena pyriformis

Asad Ud-Daula
Abstract A high throughput culture methodology of unicellular eukaryote Tetrahymena pyriformis, strain GL were used for the determination of catecholamines toxicity and their metabolism. Catecholamines exhibited acute toxicity to Tetrahymena cells where dopamine and L -DOPA showed higher toxic potential of EC10 (0.39 and 0.63 mg/L, respectively) and EC20 (1.1 and 1.0 mg/L, respectively). All the testing catecholamines were highly degradable in the PPY-medium due to the oxidizing environment during incubation. They were also naturally synthesized and released by Tetrahymena cells into the culture medium and increasingly accumulated with time where as noradrenalin demonstrated significant results. Cells were exposed with physiological concentration (0.12 mg/L) and one higher concentration (8.0 mg/L) of catecholamines, resulting noradrenalin depletion and in vivo generation of a metabolite in response to dopamine with higher concentration treatment. This dopamine metabolite was relatively nonpolar compared with the catecholamines and was eluted later from the reverse phase C-18 column. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009. [source]

Toxicity assessment of reference and natural freshwater sediments with the LuminoTox assay

P. M. Dellamatrice
Abstract We examined the possibility of adapting the LuminoTox, a recently-commercialized bioanalytical testing procedure initially developed for aqueous samples, to assess the toxic potential of sediments. This portable fluorescent biosensor uses photosynthetic enzyme complexes (PECs) to rapidly measure photosynthetic efficiency. LuminoTox testing of 14 CRM (Certified Reference Material) sediments was first undertaken with (1) a "solid phase assay" (Lum-SPA) in which PECs are in intimate contact with sediment slurries for a 15 min exposure period and (2) an elutriate assay (Lum-ELU) in which PECs are exposed for 15 min to sediment water elutriates. CRM sediment toxicity data were then compared with those generated with the Microtox Solid Phase Assay (Mic-SPA). A significant correlation (P < 0.05) was shown to exist between Lum-SPA and Mic-SPA, indicating that both tests display a similar toxicity response pattern for CRM sediments having differing contaminant profiles. The sediment elutriate Lum-ELU assay displayed toxicity responses (i.e. measurable IC20s) for eight of the 14 CRM sediments, suggesting that it is capable of determining the presence of sediment contaminants that are readily soluble in an aqueous elutriate. Lum-SPA and Mic-SPA bioassays were further conducted on 12 natural freshwater sediments and their toxicity responses were more weakly, yet significantly, correlated. Finally, Lum-SPA testing undertaken with increasing mixtures of kaolin clay confirmed that its toxicity responses, in a manner similar to those reported for the Mic-SPA assay, are also subject to the influence of grain size. While further studies will be required to more fully understand the relationship between Lum-SPA assay responses and the physicochemical makeup of sediments (e.g., grain size, combined presence of natural and anthropogenic contaminants), these preliminary results suggest that LuminoTox testing could be a useful screen to assess the toxic potential of solid media. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 395,402, 2006. [source]

Avoidance tests in site-specific risk assessment,influence of soil properties on the avoidance response of collembola and earthworms,

Tiago Natal-da-Luz
Abstract The ability of organisms to avoid contaminated soils can act as an indicator of toxic potential in a particular soil. Based on the escape response of earthworms and Collembola, avoidance tests with these soil organisms have great potential as early screening tools in site-specific assessment. These tests are becoming more common in soil ecotoxicology, because they are ecologically relevant and have a shorter duration time compared with standardized soil toxicity tests. The avoidance response of soil invertebrates, however, can be influenced by the soil properties (e.g., organic matter content and texture) that affect behavior of the test species in the exposure matrix. Such an influence could mask a possible effect of the contaminant. Therefore, the effects of soil properties on performance of test species in the exposure media should be considered during risk assessment of contaminated soils. Avoidance tests with earthworms (Eisenia andrei) and springtails (Folsomia candida) were performed to identify the influence of both organic matter content and texture on the avoidance response of representative soil organisms. Distinct artificial soils were prepared by modifying quantities of the standard artificial soil components described by the Organization for Economic Co-operation and Development to achieve different organic matter and texture classes. Several combinations of each factor were tested. Results showed that both properties influenced the avoidance response of organisms, which avoided soils with low organic matter content and fine texture. Springtails were less sensitive to changes in these soil constituents compared with earthworms, indicating springtails can be used for site-specific assessments of contaminated soils with a wider range of respective soil properties. [source]

Toxicological characterization of 2,4,6-trinitrotoluene, its transformation products, and two nitramine explosives

Judith Neuwoehner
Abstract The soil and groundwater of former ordnance plants and their dumping sites have often been highly contaminated with the explosive 2,4,6-trinitrotoluene (2,4,6-TNT) leading to a potential hazard for humans and the environment. Further hazards can arise from metabolites of transformation, by-products of the manufacturing process, or incomplete combustion. This work examines the toxicity of polar nitro compounds relative to their parent compound 2,4,6-TNT using four different ecotoxicological bioassays (algae growth inhibition test, daphnids immobilization test, luminescence inhibition test, and cell growth inhibition test), three genotoxicological assays (umu test, NM2009 test, and SOS Chromotest), and the Ames fluctuation test for detection of mutagenicity. For this study, substances typical for certain steps of degradation/transformation of 2,4,6-TNT were chosen for investigation. This work determines that the parent compounds 2,4,6-TNT and 1,3,5-trinitrobenzene are the most toxic substances followed by 3,5-dinitrophenol, 3,5-dinitroaniline and 4-amino-2-nitrotoluene. Less toxic are the direct degradation products of 2,4,6-TNT like 2,4-dinitrotoluene, 2,6-dinitrotoluene, 2-amino-4,6-dinitrotoluene, and 4-amino-2,6-dinitrotoluene. A weak toxic potential was observed for 2,4,6-trinitrobenzoic acid, 2,4-diamino-6-nitrotoluene, 2,4-dinitrotoluene-5-sulfonic acid, and 2,6-diamino-4-nitrotoluene. Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine and hexahydro-1,3,5-trinitro-1,3,5-triazine show no hint of acute toxicity. Based on the results of this study, we recommend expanding future monitoring programs of not only the parent substances but also potential metabolites based on conditions at the contaminated sites and to use bioassays as tools for estimating the toxicological potential directly by testing environmental samples. Site-specific protocols should be developed. If hazardous substances are found in relevant concentrations, action should be taken to prevent potential risks for humans and the environment. Analyses can then be used to prioritise reliable estimates of risk. [source]

Development of a solvent-free, solid-phase in vitro bioassay using vertebrate cells

Stephanie K. Bopp
Abstract Miniaturized bioassays offer many advantages in exploring the toxic potential of chemicals, including small sample volumes and compatibility with high-throughput screening. One problem common to miniaturized systems, however, is the loss of test chemicals because of sorption. The idea of the current study was to use the sorption phenomenon in a positive way. It was found that contaminants sorbed to the growth surface in wells of tissue-culture plates or to the surface of selected sorbent bead materials are available to vertebrate cells growing in direct contact with the contaminant-coated surface. The use of beads provided more flexibility with regard to surface area, materials, and assay format. Biosilon, a bead cell-culture carrier made of polystyrene, was found to be most suitable. It supported cell adherence and allowed the detection of reproducible dose-response curves of an increase in cytochrome CYP1A enzyme activity by sorbed polycyclic aromatic hydrocarbons in the rainbow trout (Oncorhynchus mykiss) liver cell line, RTL-W1. The resulting bead assay provides a miniaturized, solvent-free exposure system. Potential future applications include the coupling to environmental sampling, in which the bead material is used as solid receiving phase before serving as a surface for vertebrate cells to attach and respond. [source]

Seasonal dynamics and toxicity of Cylindrospermopsis raciborskii in Lake Guiers (Senegal, West Africa)

Céline Berger
Abstract Cylindrospermopsis raciborskii is a toxic bloom-forming cyanobacterium that occurs at tropical and temperate latitudes. Despite several reports from Africa, no data were previously available about its dynamics or toxic potential there. We therefore carried out a 1-year survey of the dynamics of C. raciborskii in the main water reservoir in Senegal, Lake Guiers. Cylindrospermopsis raciborskii never formed a bloom in this lake during the period studied, but was dominant during the dry season. The only observed bloom-forming species was a diatom, Fragilaria sp., which displayed a seasonal pattern contrary to that exhibited by C. raciborskii. Principal component analysis applied to environmental and phytoplankton data showed that high C. raciborskii biomasses were mainly related to high temperature and water column stability. Tests for C. raciborskii species-related toxicity and/or toxin synthesis were performed on 21 isolated clones. All the strains isolated tested negative in mouse toxicity bioassays, toxin analysis (MS/MS) and tests for known cylindrospermopsin genes (ps, pks). The limited number of isolates studied, and the occurrence of toxic and nontoxic clones in natural cyanobacterial populations, mean that we cannot conclude that there is no C. raciborskii- associated health risk in this drinking water reservoir. [source]

Determination of the toxic potential of Bacillus cereus isolates by quantitative enterotoxin analyses

Maximilian Moravek
Abstract Haemolysin BL (HBL) and nonhaemolytic enterotoxin (Nhe), each consisting of three components, represent the major enterotoxins produced by Bacillus cereus. To evaluate the expression of these toxins, a set of 100 B. cereus strains was examined. Molecular biological characterization showed that 42% of the strains harboured the genes for HBL and 99% for Nhe. The production of all Nhe and HBL components were analyzed using specific antibodies and, in culture supernatants, detectable levels of HBL and Nhe were found for 100% of hbl- positive and 96% of nhe -positive strains. The concentrations of the HBL,L2 and NheB component ranged from 0.02 to 5.6 ,g mL,1 and from 0.03 to 14.2 ,g mL,1, respectively. Comparison of the amount of NheB produced by food poisoning and food/environmental strains revealed that the median value for all food poisoning strains was significantly higher than for the food/environmental isolates. The data presented in this study provide evidence that specific and quantitative determination of the enterotoxins is necessary to evaluate the toxic potential of B. cereus. In particular, the level of Nhe seems to explain most of the cytotoxic activity of B. cereus isolates and may indicate a highly diarrheic potential. [source]

Differential developmental toxicities of di- n -hexyl phthalate and dicyclohexyl phthalate administered orally to rats

Anne-Marie Saillenfait
Abstract The objective of this study was to evaluate the developmental toxic potential of di- n -hexyl phthalate (DnHP) and dicyclohexyl phthalate (DCHP) in rats. Pregnant Sprague,Dawley rats were exposed to DnHP or DCHP at doses of 0 (olive oil), 250, 500 and 750 mg kg,1 per day, by gavage, on gestational days (GD) 6,20. Maternal food consumption and body weight gain were significantly reduced at 750 mg kg,1 per day of DnHP and at the two high doses of DCHP. Slight changes in liver weight associated with peroxisomal enzyme induction were seen in dams treated with DnHP or DCHP. DnHP caused dose-related developmental toxic effects, including marked embryo mortality at 750 mg kg,1 per day, and presence of malformations (mainly cleft palate, eye defects and axial skeleton abnormalities) and significant decreases in fetal weight at 500 and 750 mg kg,1 per day. Significant delay of ossification and increase in the incidence of skeletal variants (e.g. supernumerary lumbar ribs) also appeared at 250 mg kg,1 per day. DCHP produced fetal growth retardation at 750 mg kg,1 per day, as evidenced by significant reduction of fetal weight. DnHP and DCHP induced a significant and dose-related decrease in the anogenital distance of male fetuses at all doses, and there was a significant increase in the incidence of male fetuses with undescended testis at 500 and 750 mg kg,1 per day of DnHP. In conclusion, DnHP showed clear embryolethality and teratogenicity, but not DCHP. There was evidence that both phthalates could alter the development of the male reproductive system after in utero exposure, DnHP being much more potent than DCHP. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Calculation of a Toxic Potential Indicator Via Chinese-Language Material Safety Data Sheets

Sheng-Bou Yen
Summary This article presents an approach to evaluating the toxic potential for products or materials using Chinese-language material safety data sheets (MSDSs). The toxic potential indicator (TPI) is one of many simple methods used to evaluate the environmental impact of toxins in products and materials. According to actual application experience in Taiwan, difficulties and problems arise in the preliminary implementation of TPI values calculated via Chinese-language MSDSs. Some adjustment techniques combining Chinese vocabulary conversion and unit transformation are proposed in this article to overcome these obstacles. The proposed procedures and evaluated results can serve as a basis for environmentally conscious product design, especially with regard to the choice of materials used in Chinese-speaking countries. [source]