Relation between physicochemical properties of phenols and their toxicity and accumulation in fish

The 96-hr LC₅₀ values of 21 substituted phenols for the guppy (Poecilia reticulata) were determined at pH levels 6–8 and related to the lipophilicity defined as log P from the 1-octanol/water system, and to the ΔpK_a value (pK_a of phenol −pK_a). Log P was the more important parameter and exhibited a good correlation with log(1/LC₅₀) at all pH levels. The contribution of ΔpK_a when introduced as a second parameter into the regression equation was dependent on the pH of water: at pH 6 it was positive but turned negative as the pH was raised to 8. If the LC₅₀ values were corrected for ionization using an empirically formulated relation between toxicity and pH, the resulting regression equation could be used to predict the toxicity at any pH from 6 to 8. When corrected for ionization, log BCF (the bioconcentration factor) of 8 phenols was highly correlated with Log P but not with ΔpK_a. The regression of log BCF on Log P sufficed to explain the regression of toxicity on lipophilicity.     

Acute toxicity of phosphate ester mixtures to invertebrates and fish

Summary The acute toxicity of three commercial phosphate ester mixtures (hydraulic fluids) was tested against two invertebrates and four fishes. Pydraul 50E was more toxic than Houghtosafe 1120 in static and flow-through tests; Pydraul 115E was the least toxic. In flow-through tests these phosphate esters were less acutely toxic than PCB's. However, sublethal reactions to the phosphates suggest a need for chronic toxicity studies.     

Acute toxicity of phosphate ester mixtures to invertebrates and fish

The acute toxicity of three commercial phosphate ester mixtures (hydraulic fluids) was tested against two invertebrates and four fishes. Pydraul 50E was more toxic than Houghtosafe 1120 in static and flow-through tests; Pydraul 115E was the least toxic. In flow-through tests these phosphate esters were less acutely toxic than PCB's. However, sublethal reactions to the phosphates suggest a need for chronic toxicity studies.     

Acute toxicity of cadmium, lead, zinc, and their mixtures to stream-resident fish and invertebrates

The authors conducted 150 tests of the acute toxicity of resident fish and invertebrates to Cd, Pb, and Zn, separately and in mixtures, in waters from the South Fork Coeur d'Alene River watershed, Idaho, USA. Field-collected shorthead sculpin (Cottus confusus), westslope cutthroat trout (Oncorhynchus clarkii lewisi), two mayflies (Baetis tricaudatus and Rhithrogena sp.), a stonefly (Sweltsa sp.), a caddisfly (Arctopsyche sp.), a snail (Gyraulus sp.), and hatchery rainbow trout (Oncorhynchus mykiss), were tested with all three metals. With Pb, the mayflies (Drunella sp., Epeorus sp., and Leptophlebiidae), a Simuliidae black fly, a Chironomidae midge, a Tipula sp. crane fly, a Dytiscidae beetle, and another snail (Physa sp.), were also tested. Adult westslope cutthroat trout were captured to establish a broodstock to provide fry of known ages for testing. With Cd, the range of 96-h median effect concentrations (EC50s) was 0.4 to >5,329 μg/L, and the relative resistances of taxa were westslope cutthroat trout ≈ rainbow trout ≈ sculpin < other taxa; with Pb, EC50s ranged from 47 to 3,323 μg/L, with westslope cutthroat trout < rainbow trout < other taxa; and with Zn, EC50s ranged from 21 to 3,704 μg/L, with rainbow trout < westslope cutthroat trout ≈ sculpin < other taxa. With swim-up trout fry, a pattern of decreasing resistance with increasing fish size was observed. In metal mixtures, the toxicities of the three metals were less than additive on a concentration-addition basis.     

Comparative toxicity of fluoranthene and pentachlorobenzene to three freshwater invertebrates

This study examined the temporal component of pentachlorobenzene lethal body residues among three freshwater invertebrates. Also, using previous fluoranthene data allowed a more detailed examination of the role of biotransformation in lethal body residues and comparisons of lethal residues across chemical classes. Time-dependent toxicity of fluoranthene and pentachlorobenzene were compared among Hyalella azteca, Chironomus tentans, and Diporeia spp. Lethal body residues required for 50% mortality (LR50) were not constant and decreased with exposure time for all species. Fluoranthene was most toxic to C. tentans with LR50 values of 0.38 micromol x g(-1) at 2 d to 0.15 micromol x g(-1) at 10 d and least toxic to Diporeia spp. with values of 9.97 micromol x g(-1) at 10 d to 3.67 micromol x g(-1) at 28 d. The LR50 values for H. azteca were intermediate and ranged from 2.25 micromol x g(-1) at 5 d to 0.56 micromol x g(-1) at 28 d. Pentachlorobenzene LR50 values were less variable among species and ranged from 1.20 micromol x g(-1) at 4 d to 0.81 micromol x g(-1) at 10 d for C. tentans, 5.0 micromol x g(-1) at 20 d and 2.75 micromol x g(-1) at 28 d for Diporeia spp., and 1.51 micromol x g(-1) at 4 d and 0.71 micromol x g(-1) at 28 d for H. azteca. When LR50 values for fluoranthene and pentachlorobenzene were compared at steady state, the lethal residues for the amphipod species were within the range expected for nonpolar narcotic chemicals (anesthetics); however, C. tentans was more sensitive to fluoranthene than pentachlorobenzene, confirming our previous hypothesis that biotransformation of fluoranthene likely produces a metabolite(s) acting by some specific mechanism of action. The information collected from this study allows a greater understanding of residue-response relationships, specifically relative species sensitivities.     

Lung retention and toxicity of some inorganic arsenic compounds

Hamsters were given weekly intratracheal instillations of arsenic trioxide, arsenic trisulfide, or calcium arsenate dust suspensions. Animals were killed at weekly intervals and the concentration of arsenic was determined in lung, liver, and hair by atomic absorption spectrophotometry following wet digestion and arsine generation. Animals treated with calcium arsenate had concentrations of arsenic in the lung about 100 times higher than that of animals given arsenic trisulfide and 1000 times higher than that of animals receiving arsenic trioxide. Arsenic trioxide was more soluble in vitro than arsenic trisulfide and calcium arsenate. Animals treated with arsenic trioxide had As concentrations in liver higher than that of animals in the other exposure groups. The substantial differentiation in lung retention between these inorganic arsenic compounds is of importance for the design and interpretation of animal carcinogenicity tests involving the respiratory tract and could also have significance in human exposure situations.     

Determinants of variability in acute to chronic toxicity ratios for aquatic invertebrates and fish

Variability in acute to chronic ratios (ACRs; median lethal or effect concentration divided by chronic value) has been of continuing interest in aquatic toxicology because of the reliance on ACRs to estimate chronic toxicity for chemicals and species with known acute toxicity data but with limited or no information for chronic toxicity. To investigate the variability and significant differences in ACRs, an extensive data set was compiled of 456 same-species pairs of acute and maximum acceptable toxicant concentrations for metals, narcotics, pesticides, and other organic chemicals. The overall median value for 456 aquatic invertebrate and fish ACRs analyzed in the present study was 8.3, with a 16,000-fold range in values (1.1-18,550) and a 32-fold range in 10th and 90th percentile values (2.5-79.5). Median ACRs for taxa, ambient habitat media, chronic test end point, and chemical mode of action (MOA)/class categories generally were similar but, in some cases, extremely variable (ranges of 1 to >10,000). No significant differences (p 相似文献   

亚砷酸钠染毒大鼠肝脏亚细胞砷含量及其砷结合物的分析

给大鼠经口亚慢性染毒亚砷酸钠后,砷主要分布于肝细胞浆,其次为微粒体、线粒体,溶酶体及细胞核;随染毒时间延长各亚细胞器砷含量升高,且在微粒体和线粒体中所占的比例逐渐增大。除核外,各亚细胞器中均有分子量45000和24000蛋白结合砷(HMWP-As和LMWP-As)及6000小分子量砷结合物(LM-As)。微粒体和线粒体中LM-As从无到有,其占各自亚细胞器砷含量的比例逐渐增大,较HMWP-As和LMWP-As的变化似乎更明显,提示LM-As的生成可能与砷对微粒体和线体牡的损伤有关。     

Development of biotic ligand models for chronic manganese toxicity to fish, invertebrates, and algae

Ecotoxicity tests were performed with fish, invertebrates, and algae to investigate the effect of water quality parameters on Mn toxicity. Models were developed to describe the effects of Mn as a function of water quality. Calcium (Ca) has a protective effect on Mn toxicity for both fish and invertebrates, and magnesium (Mg) also provides a protective effect for invertebrates. Protons have a protective effect on Mn toxicity to algae. The models derived are consistent with models of the toxicity of other metals to aquatic organisms in that divalent cations can act as competitors to Mn toxicity in fish and invertebrates, and protons act as competitors to Mn toxicity in algae. The selected models are able to predict Mn toxicity to the test organisms to within a factor of 2 in most cases. Under low-pH conditions invertebrates are the most sensitive taxa, and under high-pH conditions algae are most sensitive. The point at which algae become more sensitive than invertebrates depends on the Ca concentration and occurs at higher pH when Ca concentrations are low, because of the sensitivity of invertebrates under these conditions. Dissolved organic carbon concentrations have very little effect on the toxicity of Mn to aquatic organisms.     

Cellular uptake, subcellular distribution and toxicity of arsenic compounds in methylating and non-methylating cells

Arsenic is a known human carcinogen, inducing tumors of the skin, urinary bladder, liver and lung. Inorganic arsenic, existing in highly toxic trivalent and significantly less toxic pentavalent forms, is methylated to mono- and di-methylated species mainly in the liver. Due to the low toxicity of pentavalent methylated species, methylation has been regarded as a detoxification process for many years; however, recent findings of a high toxicity of trivalent methylated species have indicated the contrary.In order to elucidate the role of speciation and methylation for the toxicity and carcinogenicity of arsenic, systematic studies were conducted comparing cellular uptake, subcellular distribution as well as toxic and genotoxic effects of organic and inorganic pentavalent and trivalent arsenic species in both non-methylating (urothelial cells and fibroblasts) and methylating cells (hepatocytes). The membrane permeability was found to be dependent upon both the arsenic species and the cell type. Uptake rates of trivalent methylated species were highest and exceeded those of their pentavalent counterparts by several orders of magnitude. Non-methylating cells (urothelial cells and fibroblasts) seem to accumulate higher amounts of arsenic within the cell than the methylating hepatocytes. Cellular uptake and extrusion seem to be faster in hepatocytes than in urothelial cells. The correlation of uptake with toxicity indicates a significant role of membrane permeability towards toxicity. Furthermore, cytotoxic effects are more distinct in hepatocytes. Differential centrifugation studies revealed that elevated concentrations of arsenic are present in the ribosomal fraction of urothelial cells and in nucleic and mitochondrial fractions of hepatic cells. Further studies are needed to define the implications of the observed enrichment of arsenic in specific cellular organelles for its carcinogenic activity. This review summarizes our recent research on cellular uptake, distribution and toxicity of arsenic compounds in methylating and non-methylating cells.     

The influence of exposure history on arsenic accumulation and toxicity in the killifish, Fundulus heteroclitus

Exposure to arsenic is known to cause adverse effects in aquatic biota and wildlife and is of major concern to human health. Although numerous studies have investigated the toxicity of arsenic, little is known about the effects of acquired tolerance on arsenic accumulation and toxicity outside of cell culture models. Accordingly, studies were conducted on the estuarine fish, Fundulus heteroclitus, that were preexposed to nontoxic concentrations of arsenic (as sodium arsenite; 0.7 and 106 micromol As/L) for 96 h or na?ve to elevated arsenic to determine the effects of acclimation on arsenic toxicity and accumulation. Tolerance to arsenic was rapidly (96 h) acquired in killifish that were preexposed. In toxicity tests with arsenic-acclimated killifish, preexposure to 106 micromol As/L resulted in a reduction in toxicity when compared to na?ve animals. Toxicity in arsenic-acclimated fish also was distinguished by a delayed onset of mortality that manifested in dose-dependent fashion and was significant even for the lower acclimation concentration (0.7 micromol As/L). The increase tolerance acquired following preexposure to 106 micromol As/L for 96 h was associated with lower concentrations of arsenic in all monitored tissues (e.g., gill, liver, kidney) and the whole body when fish were exposed to 240 micromol As/L for an additional 96 h. In accordance with these observations, expression of the multidrug resistance- associated protein (MRP)-2 gene, which is responsible for transporting arsenic conjugated to glutathione out of cells, was increased in the liver of arsenic-acclimated fish.     

Heavy metals in sediment and their accumulation in commonly consumed fish species in Bangladesh

Six heavy metals (chromium [Cr], nickel [Ni], copper [Cu], arsenic [As], cadmium [Cd], and lead [Pb]) were measured in sediments and soft tissues of eleven commonly consumed fish species collected from an urban river in the northern part of Bangladesh. The abundance of heavy metals in sediments varied in the decreasing order of Cr > Ni > Cu > Pb > As > Cd. The ranges of mean metal concentrations in fish species, in mg/kg wet weight (ww), were as follows: Cr, 0.11–0.46; Ni, 0.77–2.6; Cu, 0.57–2.1; As, 0.43–1.7; Cd, 0.020–0.23; and Pb, 0.15–1.1. Target hazard quotients (THQs) and target carcinogenic risk (TR) showed the intake of As and Pb through fish consumption were higher than the recommended values, indicating the consumption of these fish species is associated with noncarcinogenic and carcinogenic health risks.