Chromium reduction by Escherichia coli ATCC 33456 quantitatively transferred hexavalent chromium, Cr(VI), to trivalent chromium, Cr(III). The reduced chromium was predominantly present in the external medium. Supernatant fluids of cell extract, obtained by centrifugation at 12,000 and 150,000 x g, showed almost the same Cr(VI) reduction activity, indicating that Cr(VI) reduction by E. coli ATCC...

Chromium has been and is extensively used worldwide in multiple industrial processes and is routinely discharged to the environment from such processes. Therefore, this heavy metal is a potential threat to the environment and to public health, primarily because it is non-biodegradable and environmentally persistent. Chromium exists in several oxidation states, the most stable of which are triva...

Chromium exists usually in the (III) or (VI) oxidation states. In contrast to Cr(III), which is essential to mammalian systems, Cr(VI) is dangerous for humans due to its toxicity and carcinogenic properties. Cr(VI) compounds are highly soluble, mobile and bioavailable compared to Cr(III) species. Chromium is usually analyzed using instrumental methods such as AAS or ICP, which are accurate and ...

BACKGROUND The current study evaluates the mortality of 2,354 workers first employed at a Baltimore chromate production plant between 1950 and 1974. METHODS The National Death Index (NDI Plus) was used to determine vital status and cause of death. Cumulative chromium (VI) exposure and nasal and skin irritation were evaluated as risk factors for lung cancer mortality. RESULTS There are 91,18...

In the different compartments of the environmental chromium occurs mainly in the oxidation states (III) and (VI). Although Cr(III) is an essential trace element for humans, Cr(VI) is highly cancerogenic and mutagenic. It is, therefore, necessary for risk assessment not only to determine total chromium, but also to determine chromium species, especially Cr(VI). Hexavalent chromium can be determi...

Biosorption is a process, which represents a biotechnological innovation as well as a cost effective excellent tool for removing heavy metals from aqueous solutions. The kinetics and equilibrium of the biosorption of Chromium (VI) from aqueous solution were investigated using immobilized mixed biosorbents of Annona squamosa seeds and Aspergillus niger in a batch system. The biosorption characte...

Chromium contamination in the area of the Radomka river basin in Poland has lead to significant environmental problems. Therefore, chromium redox transformations were investigated in the aquatic environment under conditions as close to natural as possible at intermediate pH and in the presence of original bottom sediment and dissolved oxygen. Reduction of Cr(VI) in the Radomka river water occur...

A high-performance liquid chromatographic method with UV detection, based on chelation with morpholine-4-carbodithioate (MDTC), has been developed for the speciation of chromium. Simultaneous preconcentration of Cr(III) and Cr(VI) in aqueous solutions was achieved by extraction of metal species in chloroform as MDTC complexes. The separation of MDTC chelates of Cr(III) and Cr(VI) was realized o...

Heavy metals are the intrinsic component of the environment with both essential and nonessential types. Their excessive levels pose a threat to plant growth and yield. Also, some heavy metals are toxic to plants even at very low concentrations. The present investigation (a pot experiment) was conducted to determine the affects of varying chromium(VI) levels (0.0, 0.5, 1.0, 2.0, and 4.0 mg chrom...

Peroxochromium(IV) complexes are putative DNA-damaging and mutagenic agents in chromium(VI)-mediated carcinogenesis. The reaction between aquaethylenediaminebis(peroxo)chromium(IV) and glutathione at neutral pH exhibits a cyclic redox process displaying a persistent recycling of Cr(IV) and Cr(VI) with the intervention of chromium(V) intermediates. The coordination by a glutathione molecule trig...