13 research outputs found
Mixtures of Chemical Pollutants at European Legislation Safety Concentrations: How Safe Are They?
The risk posed by complex chemical mixtures in the environment to wildlife and humans is increasingly debated, but has been rarely tested under environmentally relevant scenarios. To address this issue, two mixtures of 14 or 19 substances of concern (pesticides, pharmaceuticals, heavy metals, polyaromatic hydrocarbons, a surfactant, and a plasticizer), each present at its safety limit concentration imposed by the European legislation, were prepared and tested for their toxic effects. The effects of the mixtures were assessed in 35 bioassays, based on 11 organisms representing different trophic levels. A consortium of 16 laboratories was involved in performing the bioassays. The mixtures elicited quantifiable toxic effects on some of the test systems employed, including i) changes in marine microbial composition, ii) microalgae toxicity, iii) immobilization in the crustacean Daphnia magna, iv) fish embryo toxicity, v) impaired frog embryo development, and vi) increased expression on oxidative stress-linked reporter genes. Estrogenic activity close to regulatory safety limit concentrations was uncovered by receptor-binding assays. The results highlight the need of precautionary actions on the assessment of chemical mixtures even in cases where individual toxicants are present at seemingly harmless concentration
Mixtures of chemical pollutants at European legislation safety concentrations: how safe are they?
The risk posed by complex chemical mixtures in the environment to wildlife and humans is increasingly debated, but has been rarely tested under environmentally relevant scenarios. To address this issue, two mixtures of 14 or 19 substances of concern (pesticides, pharmaceuticals, heavy metals, polyaromatic hydrocarbons, a surfactant, and a plasticizer), each present at its safety limit concentration imposed by the European legislation, were prepared and tested for their toxic effects. The effects of the mixtures were assessed in 35 bioassays, based on 11 organisms representing different trophic levels. A consortium of 16 laboratories was involved in performing the bioassays. The mixtures elicited quantifiable toxic effects on some of the test systems employed, including i) changes in marine microbial composition, ii) microalgae toxicity, iii) immobilization in the crustacean Daphnia magna, iv) fish embryo toxicity, v) impaired frog embryo development, and vi) increased expression on oxidative stress-linked reporter genes. Estrogenic activity close to regulatory safety limit concentrations was uncovered by receptor-binding assays. The results highlight the need of precautionary actions on the assessment of chemical mixtures even in cases where individual toxicants are present at seemingly harmless concentrations
Standoff detection of explosives and buried landmines using fluorescent bacterial sensor cells
Nanoscale Plasmonic V-Groove Waveguides for the Interrogation of Single Fluorescent Bacterial Cells
We experimentally
demonstrate the interrogation of an individual <i>Escherichia
coli</i> cell using a nanoscale plasmonic V-groove
waveguide. Several different configurations were studied. The first
involved the excitation of the cell in a liquid environment because
it flows on top of the waveguide nanocoupler, while the obtained fluorescence
is coupled into the waveguide and collected at the other nanocoupler.
The other two configurations involved the positioning of the bacterium
within the nanoscale waveguide and its excitation in a dry environment
either directly from the top or through waveguide modes. This is achieved
by taking advantage of the waveguide properties not only for light
guiding but also as a mechanical tool for trapping the bacteria within
the V-grooves. The obtained results are supported by a set of numerical
simulations, shedding more light on the mechanism of excitation. This
demonstration paves the way for the construction of an efficient bioplasmonic
chip for diverse cell-based sensing applications