In the study, Zn in the size of 40-60 nm and 80-100 nm and ZnO in the size of 10-30 nm were applied to A. salina and D. magna individuals in 7 groups with 3 repetitions. Measurements were made at 24th, 48th and 72nd hours and elimination values were examined at +24 h. LC50 values of NPs were determined and chemical analysis (metal accumulation and elimination), ion quantities which were given to the environment and the survival rates of organisms were determined after the exposure. According to the results of phase contrast microscopy, it was found that both experimental organisms absorbed the NPs in the medium level. In the toxicity results of D. magna, it can be said that Zn NP (40-60 nm) has a highly toxic effect only at 50 ppm concentration for 48 h and lethal dose can be accepted as of 5 ppm at the end of 72 h. In A. salina individuals, it is clearly seen that there is an increase in mortality in organisms parallel to the dose increase. Although all NPs were applied to organisms in low doses corresponding to environmental values, it was observed that toxic effect was in parallel with the increase in time. It is clearly known that there is the inverse proportion between the size of NPs and the toxic effect. The smaller the size of NPs is, the higher the toxic effect becomes When the results of Zn accumulation and elimination of A. salMa and D. magna individuals exposed to the Zn and ZnO NPs were examined; it was found that accumulation and elimination occurred in parallel with the increase in concentration at each application hour and elimination. Intensive and possible misuse of nanoscale materials is one of the biggest threats to the environment and all living things worldwide. (C) 2019 Elsevier B.V. All rights reserved.