Microplastics are emerging persistent contaminants of increasing concern. Although microplastics have been extensively detected in aquatic environments, their occurrence in soil ecosystems remains largely unexplored. This review focused on recent progress in analytical methods, pollution characteristics and ecological effects of microplastics in soils. In spite of the presence of microplastics in soils, no standardized methods are available for the quantification. Uniform protocols including microplastic extraction and identification are urgently needed to develop. In soil environments, main sources of microplastics include mulching film, sludge, wastewater irrigation and atmospheric deposition. The fate of microplastics is closely related to soil physio-chemistry and biota. Existing evidence shows that microplastics can influence soil biota at different trophic levels, and even threaten human health through food chains. Therefore, further research is needed to fully reveal the fate and ecological risks of microplastics in soils; and necessary action is required to control microplastic pollution in terrestrial ecosystems.

Microplastics in soils: Analytical methods, pollution characteristics and ecological risks

Microplastics in the marine environment: Current trends in environmental pollution and mechanisms of toxicological profile

(Nano)microplastics (N/MPs) are emerging contaminants of increasing concern. However, little is known about the potential toxicity difference between nanoplastics and microplastics on organisms. In this study, we investigated the effects of polystyrene N/MPs with diameter sizes of 100 and 500 nm at the nanoscale and 1.0, 2.0 and 5.0 μm at the microscale on the survival, lifespan, motor behavior, movement-related neurons and oxidative stress in Caenorhabditis elegans. After 3 days of exposure to 1.0 mg L−1 polystyrene particles of the five sizes, the 1.0 μm group had the lowest survival rate, the largest decrease in body length and the shortest average lifespan in nematodes. We demonstrated that exposure to N/MPs accelerated the frequency of body bending and head thrashing, and increased crawling speed, which indicate that N/MPs can induce size-dependent excitatory toxicity on locomotor behavior. Of the five sizes of N/MPs, 1.0 μm particles significantly downregulated the expression of unc-17 and unc-47, and resulted in obvious damage to cholinergic and GABAergic neurons. We also found that polystyrene N/MPs significantly elevated the expression of gst-4, which encodes glutathione S-transferase-4, a key enzyme in oxidative stress. Additionally, N/MPs-induced oxidative damage was effectively attenuated by natural antioxidants, curcumin and oligometric proanthocyanidins. Taken together, these findings suggest that (nano)microplastics can exert size-dependent toxicity and have extensive impacts on organisms.

Polystyrene (nano)microplastics cause size-dependent neurotoxicity, oxidative damage and other adverse effects in Caenorhabditis elegans

Potential human health risks due to environmental exposure to nano- and microplastics and knowledge gaps: A scoping review.

The issue of microplastic pollution emerged from the marine environment, but the terrestrial environment is estimated to receive annually 4–23 times more plastic wastes. Microplastic pollution in t...

Microplastics in the soil environment: Occurrence, risks, interactions and fate – A review

The potential toxicity of nanoplastics to environmental organisms has gradually received great attention recently. We employed the in vivo assay system of Caenorhabditis elegans to investigate the possible transgenerational toxicity of nanopolystyrene particles and the underlying cellular mechanisms. After prolonged exposure, we observed the toxicity of nanopolystyrene particles at concentrations higher than 10 μg L−1. The transgenerational toxicity was further detected in nematodes exposed to nanopolystyrene particles at concentrations higher than 100 μg L−1. This observed transgenerational toxicity of nanopolystyrene particles might be mainly due to the translocation of nanopolystyrene particles into reproductive organs such as the gonad, which potentially in turn led to the transfer of nanopolystyrene particles to the next generation. Leachates from nanopolystyrene particles at concentrations in the range of μg L−1 did not contribute to the development of this transgenerational toxicity. Enhancement of intestinal permeability and extension of defecation cycle length provide the explanation for the observed accumulation and translocation of nanopolystyrene particles in reproductive organs. Therefore, our results demonstrate the potential transgenerational toxicity of nanopolystyrene particles in the range of μg L−1 in environmental organisms.

Transgenerational toxicity of nanopolystyrene particles in the range of μg L−1 in the nematode Caenorhabditis elegans

Using acs-22 mutant Caenorhabditis elegans to detect the toxicity of nanopolystyrene particles.

Amino modification enhances reproductive toxicity of nanopolystyrene on gonad development and reproductive capacity in nematode Caenorhabditis elegans

Toxicity comparison between pristine and sulfonate modified nanopolystyrene particles in affecting locomotion behavior, sensory perception, and neuronal development in Caenorhabditis elegans

The potential adverse effects of nanoplastics have gradually gained significant attention. Herein, we employed Caenorhabditis elegans to investigate the possible neurotoxic effects of nanopolystyrene particles on the development and function of D-type GABAergic motor neurons. Nanopolystyrene (1000 μg L−1) induced the neurodegeneration of D-type motor neurons in wild-type nematodes, and nanopolystyrene (≥100 μg L−1) further induced the neurodegeneration phenotype in nematodes with a mutation in sod-3, encoding a Mn-SOD or acs-22, which governs the functional state of the intestinal barrier. Meanwhile, nanopolystyrene (≥10 μg L−1) decreased head thrash and body bend, and nanopolystyrene (≥100 μg L−1) altered forward and backward movements in wild-type nematodes. Moreover, nanopolystyrene (≥1 μg L−1) decreased head thrash and body bend and nanopolystyrene (≥10 μg L−1) affected forward and backward movements in sod-3 or acs-22 mutant nematodes. Along with the neurotoxicity observed in nanopolystyrene-exposed nematodes, nanopolystyrene exposure induced a dynamic autophagy induction. RNAi knockdown of lgg-1 encoding a key regulator of autophagy induced susceptibility to the neurotoxic effects of nanopolystyrene particles on the development and function of D-type motor neurons, implying the association of dynamic autophagy induction with the neurotoxicity induced by nanopolystyrene particles. Our results highlight the potential neurotoxicity of long-term nanoplastic exposure in organisms.

Man Qu

Papers

Transgenerational toxicity of nanopolystyrene particles in the range of μg L−1 in the nematode Caenorhabditis elegans

Using acs-22 mutant Caenorhabditis elegans to detect the toxicity of nanopolystyrene particles.

Amino modification enhances reproductive toxicity of nanopolystyrene on gonad development and reproductive capacity in nematode Caenorhabditis elegans

Toxicity comparison between pristine and sulfonate modified nanopolystyrene particles in affecting locomotion behavior, sensory perception, and neuronal development in Caenorhabditis elegans

Neuronal damage induced by nanopolystyrene particles in nematode Caenorhabditis elegans