Potential Effects of Environmental and Occupational Exposure to Microplastics: An Overview of Air Contamination.

Microplastics (MPs) are now ubiquitous environmental contaminants that lead to unavoidable human exposure; they have received increasing attention in recent years and have become an emerging area of research. The greatest concern is the negative impacts of MPs on marine, fresh-water, and terrestrial ecosystems, as well as human health, to the extent that the World Health Organization (WHO) calls for increased research and standardized methods to assess exposure to MPs. Many countries and international organizations are implementing or proposing legislation in this regard. This review aims to summarize the current state of legislation, indoor and outdoor contamination, and potential human health risk due to exposure to airborne MPs, considering that occupational exposure to MPs is also becoming a growing area of concern. Even though research regarding MPs has continuously increased in the last twenty years, the effects of MPs on human health have been scarcely investigated, and toxicity studies are still limited and not directly comparable, due to the lack of standardized studies in this field.

Size dependent uptake and trophic transfer of polystyrene microplastics in unicellular freshwater eukaryotes.

Microplastics (MP) have become a well-known and widely investigated environmental pollutant. Despite the huge amount of new studies investigating the potential threat posed by MP, the possible uptake and trophic transfer in lower trophic levels of freshwater ecosystems remains understudied. This study aims to investigate the internalization and potential trophic transfer of fluorescent polystyrene (PS) beads (0.5 µm, 3.6 × 108 particles/mL; 6 µm, 2.1 × 105 particles/mL) and fragments (<30 µm, 5 × 103 particles/mL) in three unicellular eukaryotes. This study focuses on the size-dependent uptake of MP by two freshwater Ciliophora, Tetrahymena pyriformis, Paramecium caudatum and one Amoebozoa, Amoeba proteus, serving also as predator for experiments on potential trophic transfer. Size-dependent uptake of MP in all three unicellular eukaryotes was shown. P. caudatum is able to take up MP fragments up to 27.7 µm, while T. pyriformis ingests particles up to 10 µm. In A. proteus, small MP (PS0.5µm and PS6µm) were taken up via pinocytosis and were detected in the cytoplasm for up to 14 days after exposure. Large PS-MP (PS<30µm) were detected in A. proteus only after predation on MP-fed Ciliophora. These results indicate that A. proteus ingests larger MP via predation on Ciliophora (PS<30µm), which would not be taken up otherwise. This study shows trophic transfer of MP at the base of the aquatic food web and serves as basis to study the impact of MP in freshwater ecosystems.

Beyond microplastics: Water soluble synthetic polymers exert sublethal adverse effects in the freshwater cladoceran Daphnia magna.

Plastic pollution is considered one of the causes of global change. However, water soluble synthetic polymers (WSSPs) have been neglected so far, although they are used in several industrial, dietary, domestic and biomedical products. Moreover, they are applied in wastewater treatment plants (WWTPs) as flocculants and coagulant agents. Hence, their presence in the aquatic environment as well as their uptake by aquatic organisms is probable, whereas no data are available regarding their potential adverse effects. Here we show in the freshwater key species D. magna exposed to five different WSSPs life history changes along with an altered level of reactive oxygen species, although acute mortality was not observed. Since daphnids act as keystone species in lake ecosystems by controlling phytoplankton biomass, even sublethal effects such as WSSPs induced changes in life history may result in cascading effects, from lower to higher trophic levels, which in turn could affect the whole food web.

Prenatal exposure to triclosan induced brain telomere shortening in a wild bird species.

Exposure to the antimicrobial agent Triclosan (TCS) induces oxidative stress in diverse organisms, including birds. However, whether TCS-induced oxidative stress effectively translates into detrimental effects is still unclear. The present study examined whether prenatal TCS exposure induces oxidative stress and telomere shortening in the brain and the liver of near-term embryos of the yellow-legged gull (Larus michahellis). Prenatal TCS exposure caused a significant overproduction of reactive oxygen species (ROS) in the brain, but no oxidative damage occurred. Telomeres of TCS-exposed embryos had brain telomeres 30 % shorter compared to controls, probably because the relatively modest antioxidant defenses of this organ during prenatal development cannot counteract the impact of the TCS-induced ROS. No telomere shortening was observed in the liver. Our results demonstrated that prenatal exposure to TCS in wild bird species can modulate the oxidative status and induce telomere shortening in the brain of the yellow-legged gull embryos.

Methamphetamine exposure modulated oxidative status and altered the reproductive output in Daphnia magna.

Methamphetamine (METH) is a central nervous system stimulant drug whose use has increased in the last few years worldwide. After the ingestion of even a single dose, METH is excreted by the organism and enters the aquatic ecosystems, whereby concentrations up to hundreds of ng/L were measured in both sewage and surface waters. Although the environmental concentrations are currently quite low, the high biological activity of METH might cause adverse effects towards non-target organisms. However, to date the information on METH toxicity towards aquatic organisms is limited. Thus, the present study aimed at investigating biochemical and behavioral effects induced by METH exposure towards the Cladoceran Daphnia magna. A 21-days exposure to two environmental concentrations of METH (50 ng/L and 500 ng/L) was performed. At selected time points (7, 14 and 21 days) the amount of pro-oxidant molecules, the activity of antioxidant enzymes (SOD, CAT, GPx) and levels of lipid peroxidation (LPO) were measured as oxidative stress-related endpoints. Changes in swimming activity and reproductive output were assessed as behavioral endpoints. METH exposure affected the oxidative status of D. magna specimens at both tested concentrations, although no oxidative damage occurred. Although METH did not modulate the swimming activity of D. magna, a significant, positive effect on reproductive output, in terms of number of offspring was found. Our results showed that low concentrations of METH might represent a threat for D. magna, affecting the health status of this aquatic species at different level of biological organization.