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We developed a simple and fast microplate assay for evaluation of the antimicrobial activity of electrospun nanofiber filtration membranes or similar porous materials for water treatment technologies. Resazurin (alamarBlue®) was used as an indicator of the amount of viable experimental microorganisms Gram-negative Escherichia coli, Gram-positive Enterococcus faecalis, and natural wastewater treatment plant effluent bacteria. A bacterial inoculum of concentration 1–3 × 105 CFU mL−1 was pipetted onto the surface of assessed both functionalized and respective control membranes and incubated in 12-well plates for 4 h at 37 °C. Kinetics of resazurin metabolization, i.e. its reduction to fluorescent resorufin, was evaluated fluorimetrically (λex520/λem590 nm). A number of viable bacteria on the membranes expressed as CFU mL−1 was calculated from the kinetic curves by using calibration curves that were constructed for both experimental bacterial species. Antimicrobial activities of the membranes were evaluated by either resazurin assay or modified ISO 20743 plate count assay. Results of both assays showed the significant antimicrobial activity of membranes functionalized with silver nanoparticles for both bacterial species and wastewater treatment plant effluent bacteria as well (log CFU reduction compared to control membrane > 4), while membranes containing specific quaternary ammonium salts were inefficient (log CFU reduction < 1). The suitability of resazurin microplate assay for testing nanofiber filtration membranes and analogous matrices has proven to be a faster and less demanding alternative to the traditionally used approach providing comparable results.

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Phthalates are organic substances used mainly as plasticisers in the manufacture of plastics. They are ubiquitous in the environment. Although tests in rodents have demonstrated numerous negative effects of phthalates, it is still unclear whether the exposure to phthalates may also damage human health. This paper describes phthalate toxicity and toxicokinetics, explains the mechanisms of phthalate action, and outlines the issues relating to the presence of phthalates in foods. &nbsp;

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The aim of the study was to evaluate the xeno-oestrogenic potential of propylparaben in vivo using zebrafish (Danio rerio). Experimental juvenile zebrafish (20 days post hatching) were fed a feed containing 500, 1000, or 2000 mg·kg -1 of propylparaben, fish in a positive control group were given a feed treated with 20 mg·kg -1 of 17β-oestradiol, and the control fish were given the feed free of either tested substance. The exposure of fish to propylparaben did not affect vitellogenesis after 20 days exposure but seemed to influence the sex differentiation processes, as evidenced by a sex ratio significantly skewed towards females in the group fed 500 mg·kg -1 of propylparaben following 45 days of exposure. The potential of the fish to respond to oestrogenic stimulation was confirmed, since significantly higher vitellogenin concentrations were detected in the fish from the positive control group.

Mikula P., Z. Svobodová: Brominated Flame Retardants in the Environment: Their Sources and Effects (a Review). Acta Vet. Brno 2006, 75: 587-599. Brominated flame retardants (BFRs) are organic substances frequently used in many industries. The most important group within BFRs are polybrominated diphenyl ethers (PBDEs). Because they persist in the environment, accumulate in food chains and have toxic effects, they are a potential health risk both for animals and humans. Polybrominated diphenyl ethers may disrupt processes of hormonal regulation in living organisms by reducing thyroxine concentrations in the plasma of the exposed individuals. In vitro studies have demonstrated the ability of these substances to bind to estrogen and androgen receptors. Tests on rodents have also demonstrated neurotoxicity of some of the PBDEs. Although industrial use of PBDEs is now regulated to a large extent, PBDEs have already been detected in areas with no apparent industrial load, e.g. in Greenland. This article presents an overview of BFRs-related issues with a particular emphasis on PBDEs, describes toxic effects of those substances and their metabolism in living organisms, and discusses issues related to the incidence of PBDEs in the environment. BFRs, polybrominated diphenyl ethers, tetrabromobisphenol A, environmental endocrine disruptors, toxicity, metabolismA large number of chemical substances have recently been under an intensive scrutiny because of their possible adverse health effects on both humans and animals. These substances include the so-called brominated flame retardants (BFRs). They are substances used in a number of industries in the manufacture of polymers and synthetic resins to reduce the risk of fires. Brominated flame retardants are used in building materials (polymer foams, thermal insulations), electric cable insulation, consumer electronics (TV sets, VCRs, computers) and household furnishings (furniture upholstery, carpets, etc.). Brominated flame retardants contain different numbers of bromine atoms which are released from the polymer matrix by heat. They then neutralize energy-rich radicals produced during the combustion process, thus making it more difficult for the process of combustion to continue. Depending on the flame retardant bond in polymer, two groups of BFRs are distinguished. While reactive flame retardants are incorporated into polymer through covalent bonds, additive brominated flame retardants are loosely dispersed in the polymer. Tens or even hundreds of thousands of tonnes of BFRs are produced in the world every year (Table 1). The most frequently used BFRs are tetrabromobisphenol A (TBBPA), commercially produced mixtures of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD). These substances are released to the environment as a result of extensive industrial exploitation of BFRs. From the point of view of possible negative effects on human and animal health, a lot of attention has been devoted mainly to PBDEs, which may persist in the environment f...