heavy metals

/Tag:heavy metals

Cytotoxicity of Cadmium, Selenium, Zinc and Copper to Mouse Myeloma Sp2/0 Cells as Measured by the MTT Assay

Inessa Remez, Leonid Rabkin, Hackel Veksler and Maija Baumane

As part of our general programme to test the toxicity in vitro of heavy metals and, in particular, the interactive cytotoxicity of combinations of these metals, the MTT (tetrazolium) assay was used to test the cytotoxicities of cadmium [Cd(O2CCH3)2], selenium (Na2SeO3), zinc (ZnSO4) and copper (CuSO4) with an established mouse myeloma cell line (Sp2/0). The influence on the cytotoxicity of cadmium of added subtoxic concentrations of the other three metals was also studied. The IC50 values (50% inhibitory concentrations) to the Sp2/0 cells were as follows: Cd — 10μM, Se — 1μM, Zn — 10μM and Cu — 100μM. When selenium, zinc and copper at high, subtoxic concentrations (10nM, 1μM and 1μM, respectively) were each combined with clearly toxic concentrations of cadmium (10μM and 100μM), the cytotoxicity increase was significant for the cadmium-zinc combination. Previous studies showed that cadmium-zinc combinations at low concentration (5 × 10–9M) had a synergistic stimulatory effect on cell proliferation in vitro. The present study showed that a toxic concentration of cadmium (0.1mM) and a sub-toxic concentration of zinc (1μM) have a synergistic cytotoxic effect in vitro.
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The Effects of Heavy Metals on Common Carp White Blood Cells In Vitro

Malgorzata Witeska and Marta Wakulska

The in vitro effects of cadmium, copper, lead and zinc, and various cadmium compounds (chloride, sulphate and nitrate) on common carp (Cyprinus carpio) lymphocyte viability and phagocyte activity, were evaluated. The percentage of dead lymphocytes was determined after Trypan blue staining, and phagocyte activity was measured by using the nitroblue tetrazolium (NBT) reduction test. Lead was the most toxic to lymphocytes — the maximum mortality exceeded 30%, and was significantly higher at 1μM of lead, compared to the control. The maximum mortality caused by cadmium was below 10%, but was significantly elevated with 5μM or more of cadmium. Zinc induced lymphocyte mortality from 10μM, whilst no effect was observed with copper. The incubation of full blood with the three cadmium compounds (at 5mg/l of cadmium) showed that cadmium nitrate and cadmium sulphate were more toxic (over 35% and 25% mortality, respectively) than cadmium chloride (about 15% mortality). This was confirmed by the results of tests on isolated cells —1mg/l of cadmium as nitrate and sulphate increased lymphocyte mortality compared to the control and cadmium chloride. Phagocytic activity was less sensitive to heavy metals than was lymphocyte viability. It was significantly reduced following exposure to 50μM and 100μM cadmium, and 100μM zinc, but no effects were observed with either lead or copper.
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The Use of Bioassays for the Risk Assessment of Toxic Leachates: An Experimental Study

Natalya Irha and Irina Blinova

Solid wastes from the oil-shale industry produce leachates containing toxic compounds such as heavy metals and persistent polycyclic aromatic hydrocarbons (PAH). The hazard to the environment represented by waste leachates depends not only on their chemical composition, but also on the mobility and bioavailability of toxic contaminants in soils. We evaluated the applicability of bioassays for toxicity assessment of the bioavailable fraction of heavy metals and PAH in soils, in experiments with samples of four different soil types (Rendzina, Brown pseudopodzolic, Typical brown, Sodpodzolic), the pH of which ranged from 6.2 to 7.2. The toxicity of the bioavailable fraction of the soil contaminants was assessed with the dehydrogenase enzyme activity assay, and with a Toxkit microbiotest with the crustacean, Thamnocephalus platyurus, after treatment of the soil samples with an artificial solution containing chromium (III), lead (II),
copper (II), cadmium (II) and pyrene. The test results confirm those of earlier experiments, which characterised the sorption potential of investigated soils for the same compounds. Both tests turned out to be sufficiently sensitive, and hence can be recommended as effective and useful tools for the assessment of the bioavailable fraction of soil contaminants.
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