Acute toxicity of organic pesticides to Daphnia magna is unchanged by co-exposure to polystyrene microplastics

Daphnia magna were exposed to two pesticides in the presence or absence of microplastics (300 000 particles ml−1 1 µm polystyrene spheres) and to microplastics alone. The pesticides were dimethoate, an organophosphate insecticide with a low log Kow, and deltamethrin, a pyrethroid insecticide with a high log Kow. Daphnia were exposed to a nominal concentration range of 0.15, 0.31, 0.63, 1.25, 2.5, 5 mg l−1 dimethoate and 0.016, 0.08, 0.4, 2, 5 and 10 µg l−1 deltamethrin. Exposure to polystyrene microplastics alone showed no effects on Daphnia magna survival and mobility over a 72 h exposure. In the dimethoate exposures, mobility and survival were both affected from a concentration of 1.25 mg l−1, with effects were seen on mobility from 28 h and survival from 48 h, with greater effects seen with increasing concentration and exposure time. In deltamethrin exposures, survival was affected from a concentration of 0.4 µg l−1 and mobility from a concentration of 0.08 µg l−1. Effects of deltamethrin on mobility were seen from 5 h and on survival from 28 h, with greater effects on survival and mobility seen with increasing concentration and exposure time. Contrary to expectations, pesticide toxicity to Daphnia magna was not affected by the presence of microplastics, regardless of chemical binding affinity (log Kow). This therefore suggests that polystyrene microplastics are unlikely to act as a significant sink, nor as a vector for increased uptake of pesticides by aquatic organisms.

Alice A. Horton, Martina G. Vijver, Elma Lahive and al., Ecotoxicology and Environmental Safety, Volume 166, 30 December 2018, Pages 26-34

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Nanoplastic Ingestion Enhances Toxicity of Persistent Organic Pollutants (POPs) in the Monogonont Rotifer Brachionus koreanus via Multixenobiotic Resistance (MXR) Disruption

Among the various materials found inside microplastic pollution, nanosized microplastics are of particular concern due to difficulties in quantification and detection; moreover, they are predicted to be abundant in aquatic environments with stronger toxicity than microsized microplastics. Here, we demonstrated a stronger accumulation of nanosized microbeads in the marine rotifer Brachionus koreanus compared to microsized ones, which was associated with oxidative stress-induced damages on lipid membranes. In addition, multixenobiotic resistance conferred by P-glycoproteins and multidrug resistance proteins, as a first line of membrane defense, was inhibited by nanoplastic pre-exposure, leading to enhanced toxicity of 2,2′,4,4′-tetrabromodiphenyl ether and triclosan in B. koreanus. Our study provides a molecular mechanistic insight into the toxicity of nanosized microplastics toward aquatic invertebrates and further implies the significance of synergetic effects of microplastics with other environmental persistent organic pollutants.

Chang-Bum Jeong, Hye-Min Kang, Young Hwan Lee and al., Environ. Sci. Technol., Article ASAP, September 7, 2018

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Small-sized microplastics and pigmented particles in bottled mineral water

HighlightS

• 32 samples of mineral water were investigated for microparticles (down to 1 μm size).

• Water from all bottle types was contaminated with microplastics.

• Water from reusable, paper labelled bottles contained pigmented particles.

• About 90% of microplastics/pigmented particles were smaller than 5 μm.

• Potential contamination sources like the packaging material are discussed.

Barbara E. Oßmann, George Sarau, Heinrich Holtmannspötter and al., Water Research, Volume 141, 15 September 2018, Pages 307-316

The article

Distribution of Microplastics and Nanoplastics in Aquatic Ecosystems and Their Impacts on Aquatic Organisms, with Emphasis on Microalgae

Plastics, with their many useful physical and chemical properties, are widely used in various industries and activities of daily living. Yet, the insidious effects of plastics, particularly long-term effects on aquatic organisms, are not properly understood. Plastics have been shown to degrade to micro- and nanosize particles known as microplastics and nanoplastics, respectively. These minute particles have been shown to cause various adverse effects on aquatic organisms, ranging from growth inhibition, developmental delay and altered feeding behaviour in aquatic animals to decrease of photosynthetic efficiency and induction of oxidative stress in microalgae. This review paper covers the distribution of microplastics and nanoplastics in aquatic ecosystems, focusing on their effects on microalgae as well as co-toxicity of microplastics and nanoplastics with other pollutants. Besides that, this review paper also discusses future research directions which could be taken to gain a better understanding of the impacts of microplastics and nanoplastics on aquatic ecosystems.

Jun-Kit Wan, Wan-Loy Chu, Yih-Yih Kok, Choy-Sin Lee, Chapter, Part of the Reviews of Environmental Contamination and Toxicology book series, Springer

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Microplastic contamination in benthic organisms from the Arctic and sub-Arctic regions

The seafloor is recognized as one of the major sinks for microplastics (MPs). However, to date there have been no studies reported the MP contamination in benthic organisms from the Arctic and sub-Arctic regions. Therefore, this study provided the first data on the abundances and characteristics of MPs in a total of 413 dominant benthic organisms representing 11 different species inhabiting in the shelf of Bering and Chukchi Seas. The mean abundances of MP uptake by the benthos from all sites ranged from 0.02 to 0.46 items g−1 wet weight (ww) or 0.04–1.67 items individual−1, which were lower values than those found in other regions worldwide. The highest value appeared at the northernmost site, implying that the sea ice and the cold current represent possible transport mediums. Interestingly, the predator A. rubens ingested the maximum quantities of MPs, suggesting that the trophic transfer of MPs through benthic food webs may play a critical role. Fibers constituted the major type (87%) in each species, followed by film (13%). The colors of fibers were classified as red (46%) and transparent (41%), and the film was all gray. The predominant composition was polyamide (PA) (46%), followed by polyethylene (PE) (23%), polyester (PET) (18%) and cellophane (CP) (13%). The most common sizes of MPs concentrated in the interval from 0.10 to 1.50 mm, and the mean size was 1.45 ± 0.13 mm. Further studies about the temporal trends and detrimental effects of MPs remain to be carried out in benthic organisms from the Arctic and sub-Arctic regions.

Chao Fang, Ronghui Zheng, Yusheng Zhang and al., Chemosphere, Volume 209, October 2018, Pages 298–306

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Hazardous Chemicals in Plastics in Marine Environments: International Pellet Watch

Marine plastic debris, including microplastics <5 mm, contain additives as well as hydrophobic chemicals sorbed from surrounding seawater. A volunteer-based global monitoring programme entitled International Pellet Watch (IPW) is utilizing the sorptive nature of plastics, more specifically of beached polyethylene (PE) pellets, in order to measure persistent organic pollutants (POPs) throughout the world. Spatial patterns of polychlorinated biphenyls (PCBs) and organochlorine pesticides have been revealed. Original data of IPW show large piece-to-piece variability in PCB concentrations in pellets collected at each location. This is explained by the combination of slow sorption/desorption and large variabilities of speed and route of floating plastics. The sporadically high concentrations of POPs, both sorbed chemicals and hydrophobic additives, are frequently observed in pellets and the other microplastics in open ocean and remote islands. This poses a chemical threat to marine ecosystems in remote areas.

Rei Yamashita, Kosuke Tanaka, Bee Geok Yeo, Hideshige Takada, Jan A. van Franeker, Megan Dalton, Eric Dale, chapter In: The Handbook of Environmental Chemistry. Springer, pp 1-21,

The chapter

Sticky tape and simulations help assess microplastic risk

Tiny pieces of plastic, now ubiquitous in the marine environment, have long been a cause of concern for their ability to absorb toxic substances and potentially penetrate the food chain. Now scientists are beginning to understand the level of threat posed to life, by gauging the extent of marine accumulation and tracking the movement of these contaminants. (…)

N. Grover, Horizon EU magazine, 23/04/2018

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