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

The article

Single contaminant and combined exposures of polyethylene microplastics and fluoranthene: accumulation and oxidative stress response in the blue mussel, Mytilus edulis

The microplastic “vector effect” has received increasing attention. The aim of this study was to investigate the influence of polyethylene microplastic beads (PE MP) on accumulation and associated oxidative stress responses attributed to fluoranthene (Flu) in blue mussels, Mytilus edulis. Blue mussels were exposed for 96 h to four treatment groups: Flu-only, MP-only, Flu and MP coexposure, and Flu-incubated MP. Treatments were conducted at a low and high concentration (50 μg/L and 100  Flu μg/L and 100, and 1000 MP/mL). Results demonstrated that in both the gill and digestive gland, coexposure did not markedly affect Flu uptake, but this treatment significantly decreased tissue Flu concentrations. Antioxidant responses including activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidases (GPx), and levels of total glutathione (GSH) in both gills and digestive glands were significantly altered suggesting a perturbation of redox state induced by the exposure conditions. Although individual biomarkers varied, the biomarker profile enabled certain generalizations to be made. Antioxidant responses occurred more likely in gill tissue than in digestive gland. Individual contaminant exposures to Flu or MP led to varying responses, but coexposures and incubated exposures did not result in additive or synergistic effects. Exposure concentrations (i.e., low or high treatments) were not a consistent a predictor of response; and the internal Flu dose did not consistently predict outcome of various biomarkers. Importantly, MP-only exposure appeared to be capable of eliciting direct effects on the oxidative stress system as demonstrated by the activities of CAT and GPx. These findings warrant further investigation.

Gabriele Magara, Antonia Concetta Elia, Kristian Syberg & Farhan R. Khan, Journal of Toxicology and Environmental Health, Part A, Volume 81 (16), Pages 761-773, 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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Marine microplastic debris: An emerging issue for food security, food safety and human health

Recent studies have demonstrated the negative impacts of microplastics on wildlife. Therefore, the presence of microplastics in marine species for human consumption and the high intake of seafood (fish and shellfish) in some countries cause concern about the potential effects of microplastics on human health. In this brief review, the evidence of seafood contamination by microplastics is reviewed, and the potential consequences of the presence of microplastics in the marine environment for human food security, food safety and health are discussed. Furthermore, challenges and gaps in knowledge are identified. The knowledge on the adverse effects on human health due to the consumption of marine organisms containing microplastics is very limited, difficult to assess and still controversial. Thus, assessment of the risk posed to humans is challenging. Research is urgently needed, especially regarding the potential exposure and associated health risk to micro- and nano-sized plastics.

Luís Gabriel Antão Barboza, A. Dick Vethaak, Beatriz R.B.O. Lavorante and al., Marine Pollution Bulletin, Volume 133, August 2018, Pages 336–348

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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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