Nanostructured minerals developed to be used as fertilizers: biosafety evaluation

Abstract

Natural zeolites are effectively used as fertilizers, substrates, and pesticide carriers, as well as sorbents in the remediation of contaminated soils. Since nanostructured minerals exhibit unique physicochemical properties, they must be tested for toxicity and genotoxicity prior to their use in practice. The mutagenic and antimutagenic properties of a nanostructured water-zeolite suspension were first tested using two bacterial test systems: Ames test and SOS-lux test. According to the obtained data, the nanostructured water-zeolite suspension exhibits no mutagenic activity within the analyzed concentration range (0.75–400 µg/mL). In order to assess the antimutagenic activity of the nanostructured water-zeolite suspension, different types of mutagens were selected: mitomycin C, ethyl methanesulfonate, 2,4-dinitrophenylhydrazine, as well as DNA-damaging agents (ofloxacin and hydrogen peroxide). A significant antimutagenic effect of the nanostructured water-zeolite suspension at 200 μg/mL was shown against mitomycin C in the SOS-lux test (50.0% inhibition of mutagenic activity) and 2,4-dinitrophenylhydrazine in the Ames test (62.0% inhibition). For the other mutagens, a weak antimutagenic effect was observed (17.0% for ethyl methanesulfonate), while no antimutagenic effect was reported for ofloxacin and hydrogen peroxide. These differences can be attributed to the negative charge in zeolites, meaning that they can capture only positive (or neutral) molecules. Therefore, the antimutagenic effect of the nanostructured water-zeolite suspension depends on the charge of the mutagen molecule. According to the obtained results, the nanostructured water-zeolite suspension can be considered environmentally friendly, which allows it to be used for agro-industrial purposes as a fertilizer in the production of crops.