Aotearoa Impacts and Mitigation of Microplastics (AIM2) is New Zealand’s first comprehensive national program aimed at characterizing the threat microplastics pose towards ecosystems, animals, and people. AIM2 aims to address knowledge gaps surrounding the severity of New Zealand’s microplastic problem and determine if they pose a significant risk to New Zealand’s relatively pristine environments. One facet of the ‘microplastic problem’ are potential hazards associated with additives incorporated in plastics. While some of these additives have been previously identified as persistent organic pollutants others have not been fully investigated for ecotoxic potential. As part of AIM2 a short list of additives of emerging concern towards the New Zealand environment was compiled including available ecotoxicity data. Copepods, as primary consumers providing an essential link between phytoplankton and higher trophic levels, represent an important link in marine food webs that makes them ideal test organisms for investigating potential hazards associated with plastic additives. New Zealand’s native copepod species Gladioferens pectinatus was used in the present study due to its wide distribution across the countries estuaries, ease in which it can be maintained in laboratory conditions, high reproductive rate, and relatively short life cycle. The project investigated: i) the capacity of copepods to biologically uptake plastic particles at different sizes ii) the ecotoxic potential of 8 different plastic additives iii) ecotoxicity of microplastics prepared with additives iv) multigenerational effects of microplastics and associated additives. The study provides a first look at the potential environmental hazards associated with plastic additives towards New Zealand’s unique ecosystems.