Micro(nano)plastic toxicity and health effects: Special issue guest editorial

Microplastics (MPs) and nanoplastics (NPs), collectively termed “Micro(nano)plastics [MNPs]” in the special issue, compose the vast majority of plastic contaminants. MPs have become ubiquitous in the global environment (Walker, 2021, Allen et al., 2022) and NPs have also been reported in environmental samples (Cai et al., 2021). MPs have been widely detected in hundreds of animal and plant species (Karbalaei et al., 2019, Litterbase, 2022), including human placentas and blood (Leslie and Depledge, 2020, Prata et al., 2020, Ragusa et al., 2021, Leslie et al., 2022) as MPs are inhaled or consumed via food products and drinking water (Danopoulos et al., 2020, Sequeira et al., 2020, Zhang et al., 2020, Adib et al., 2022). Due to their small sizes, ubiquitous and persistent nature, the potential toxicity and health effects of MNPs have attracted significant attention and spurring rapidly-increasing research efforts (e.g., Guo et al., 2020, Castro-Castellon et al., 2021, Karbalaei et al., 2021, Khoshnamvand et al., 2021, Lahive et al., 2022, Palacio-Cortés et al., 2022). Studies on laboratory animals have mostly focused on aquatic species and have shown accumulation of MNPs in tissues and organs, causing intestinal injuries, increasing oxidative stress, triggering inflammation, neurotoxicity, and impaired development (Castro-Castellon et al., 2021, Karbalaei et al., 2021, Kukkola et al., 2021, Matthews et al., 2021). However, the actual ecological and human health impacts of MNPs are still largely unknown and few published studies have directly investigated the effects of MNPs on humans (Weber et al., 2022). Evaluating the potential adverse ecological and human health effects of MNPs across levels of biological organization has become highly imperative but challenging due to the high heterogeneity of MNPs, unknown environmental concentrations, debated vector effects for associated chemicals, and co-impact with other environmental stressors, such as climate change and other chemical contaminants (Thornton Hampton et al., 2022). Currently, the concentrations of MNPs in the environment may be low, but their increasing inputs are inevitable based on current and projected plastic production data (Borrelle et al., 2020). Therefore, it has become imperative to evaluate the potential ecological and human health impacts of MNPs.