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In order to reduce the level of transmission of diseases caused by bacteria and fungi,the development of antimicrobial additives for use in personal care,hygiene products,clothing and others has increased.Many of these additives are based on metals such as silver and titanium.The disposal of these products in the environment has raised concems pertaining to their potential harmfulness for beneficial organisms.The objective of this study was to evaluate the influence of the shape,surface chemistry,size and carrier of three additives containing silver and one with titanium dioxide (TiO2) on microcrustacean survival.Daphnia magna was used as a bioindicator for acute exposure test in suspensions from 0.0001 to 10,000 ppm.Ceriodaphnia dubia was used for chronic test in TiO2 suspensions from 0.001 to 100 ppm.D.magna populations presented high susceptibility to all silver based additives,with 100％ mortality after 24 hr of exposure.A different result was found in the acute experiments containing TiO2 suspensions,with mortality rates only after 48 hr of incubation.Even on acute and chronic tests,TiO2 did not reach a linear concentration-response versus mortality,with 1 ppm being more toxic than 10,000 ppm on acute test and 0.001 more toxic than 0.01 ppm on chronic assay.Silver based material toxicity was attributed to silver itself,and had no relation to either form (nano or ion) or carrier (silica,phosphate glass or bentonite).TiO2 demonstrated to have a low acute toxicity against D.magna.