Introduction We report, herein, in vitro, and in vivo toxicity evaluation of silver nanoparticles stabilized with gum arabic protein (AgNP-GP) in Daphnia similis, Danio rerio embryos and in Sprague Dawley rats. Purpose The objective of this investigation was to evaluate in vitro and in vivo toxicity of silver nanoparticles stabilized with gum arabic protein (AgNP-GP), in multispecies due to the recognition that toxicity evaluations beyond a single species reflect the environmental realism. In the present study, AgNP-GP was synthesized through the reduction of silver salt using the tri-alanine-phosphine peptide (commonly referred to as “Katti Peptide”) and stabilized using gum arabic protein. Methods In vitro cytotoxicity tests were performed according to ISO 10993–5 protocols to assess cytotoxicity index (IC 50 ) values. Acute ecotoxicity (EC 50 ) studies were performed using Daphnia similis , according to the ABNT NBR 15088 protocols. In vivo toxicity also included evaluation of acute embryotoxicity using Danio rerio (zebrafish) embryos following the OECD No. 236 guidelines. We also used Sprague Dawley rats to assess the toxicity of AgNP-GP in doses from 2.5 to 10.0 mg kg −1 body weight. Results AgNP-GP nanoparticles were characterized through UV (405 nm), core size (20±5 nm through TEM), hydrodynamic size (70–80 nm), Zeta (ζ) potential (- 26 mV) using DLS and Powder X ray diffraction (PXRD) and EDS. PXRD showed pattern consistent with the Ag (1 1 1) peak. EC 50 in Daphnia similis was 4.40 (3.59–5.40) μg L −1 . In the zebrafish species, LC 50 was 177 μg L −1 . Oral administration of AgNP-GP in Sprague Dawley rats for a period of 28 days revealed no adverse effects in doses of up to 10.0 mg kg −1 b.w. in both male and female animals. Conclusion The non-toxicity of AgNP-GP in rats offers a myriad of applications of AgNP-GP in health and hygiene for use as antibiotics, antimicrobial and antifungal agents.

Coal Fly ash is a major solid waste from coal-fired power stations. In Brazil, more than 4 million tons per year of fly ash are generated and only 30% is applied as raw material for cement and concrete production. The remaining is disposed in on-site ponds, nearby abandoned or active mine sites and landfills. The inadequate disposal of fly ash may pose a significant risk to the environment due to the possible leaching of hazardous pollutants into the surrounding soil and groundwater. A combination of leaching tests, cytotoxicity and ecotoxicological assays were used in this studyin order toevaluate the possible adverse effects of coal fly ash in non-target organisms. The sample was collected from coal-fired power plant located in Southern Brazil and the coal fly ash was submitted to a leaching procedure using USEPA SW 864 Method 1311. The leachate was prepared in six dilutions: 1.56%, 3.12%, 6.25%, 12.5%, 25% and 50%. Acute toxicity tests were performed on NCTC clone 929 (CCIAL-020) culture cells by neutral red uptake cytotoxicity method; acute ecotoxicity usingDaphnia similisand Danio rerio embryos according to ABNT NBR 12713 and OECD 236, respectively were employed. The cytotoxicity index (CI 50 ) obtained was 33%; the EC 50 of D. similis after 48 h of exposure to the leachate was 7.25% and the LC 50 of D. rerio after 96 h of exposure was 4.39%. The results of these bioassays indicated toxicity of the coal fly ash leachate toward exposed organisms.