Genotoxic effects of pharmaceuticals commonly detected in the environment: furosemide, atenolol, fibrates and their photoderivatives.

Pharmaceuticals may reach the environment to variable extent and generally occur in low concentrations (ng-μg/L). Biotic and/or abiotic processes may also degrade these substances and no complete information exist about the environmental fate of these compounds and their possible interactions with non-target organisms. It is unlikely to have concentrations causing acute toxicity but, often, pharmaceuticals and their derivatives act chronically at concentrations that determine different sub-lethal effects in organisms exposed, from microbial communities to the higher organisms in the food chain. The current study assessed the environmental effects of some among the most prescribed drugs for chronico-degenerative diseases: furosemide (diuretic agent), atenolol (β-blocker), fibrates as bezafibrate, fenofibrate and gemfibrozil (lipid regulators). The research was enlarged to their photoproducts obtained from solar simulator irradiation of parent compounds in aqueous medium. The study started from the evaluation of the acute and chronic toxicity to calculate the toxic ratios of these drugs on different organisms of the aquatic chain and continued detecting their potential genotoxic activity. Genotoxicity was determined using the SOS Chromotest, a quantitative bacterial colorimetric assay on Escherichia coli and the Ames test on Salmonella typhimurium, the widely used short-term test for monitoring water samples. The former is currently used to detect DNA-damaging agents that activate the SOS repair system the latter to reveal point mutations. Because of same chemicals may produce different responses in different species the range of tests also included the Trad-MCN assay with young inflorescences of the plant Tradescantia paludosa and the alkaline Comet assay using human peripheral blood leukocytes. The Trad-MCN assay records the genetic damage observed as frequency of micronuclei formed by entire chromosomes or fragments in the meiotic pollen mother cells and provides evidence of clastogenic or aneugenic damage. The Comet test does not need of cells in dividing phase and it is a useful tool to detect various forms of DNA damage such as single- and double- strand breaks and ossidative DNA base damage. As expected, toxicity results revealed that chronic effects are very higher than acute as demonstrated by the Acute/Chronic toxicity ratios that reached values about 1500 for some derivatives. The chronic data show that the compounds tested were bioactive at concentrations ranging from 0.017 to 7.36 mg/L mainly for the primary consumers Brachionus calyciflorus (rotifers) and Ceriodaphnia dubia (crustaceans) while they were no toxic or two orders of magnitude less active against algae (P. subcapitata). Variability in genotoxic responses was observed among compounds and tests, probably explainable by the different chemical characteristics of the pharmaceuticals investigated and the different endpoints of the bioassays utilized. Atenolol, furosemide and their respective derivatives showed the lowest genotoxic potential. The fibrates evidenced different responses in the four bioassays. The behavior of Gemfibrozil derivative was peculiar because it was the most active in all the bioassays performed and the only positive for S. typhimurium TA 100, the least sensitive strain to the environmental contaminants. In contrast, Gemfibrozil was the only fibrate that did not show any genotoxic effect. The use of a battery of tests appears to be a necessary methodological approach to suggest mechanisms at the base of genotoxic events.