Coexposure of Micro and Nano-Plastics with Pesticides: Cytotoxicity and Bioaccumulation Effects on a Fish Intestinal Cell Line

TL;DR

The study shows that micro and nanoplastics, when combined with pesticides, can increase toxicity and bioaccumulation in fish intestinal cells.

Contribution

The study introduces a novel investigation on the combined effects of UV-aged and pristine micro/nanoplastics with pesticides on fish intestinal cells.

Findings

UV aging reduced the adsorption capacity of microplastics for pesticides.

Nanoplastics caused more lysosomal damage than microplastics.

Fluorescently labeled micro/nanoplastics accumulated in fish intestinal cells.

Abstract

Micro- and nanoplastics (MNPs) occur in aquatic environments
and
accumulate in fish. MNPs can also adsorb other contaminants present
in aquatic environments, and there is limited information on exposure
scenarios involving MNP and pesticide mixtures. Ultraviolet (UV) radiation
and chemical oxidation of MNPs can affect the sorption properties
of MNPs and chemicals, thus altering the exposure and effects on fish.
Our study investigated the toxicity and bioaccumulation of a lindane
and dichlorodiphenyldichloroethylene (DDE) mixture adsorbed onto pristine
and weathered polyethylene (PE) MNPs. Three different PE MNP types
were used: microplastics (2–10 μm), oxidized microplastics
(10–15 μm), and a MNP mixture (0.2–9.9 μm),
and additionally each type was UV-aged for comparisons. RTgutGC cells,
derived from rainbow trout (Oncorhynchus mykiss) intestine, were used to evaluate the role of the particle type
on pesticides bioaccumulation and toxicity. Results showed that UV
aging did not affect the agglomeration in solution but decreased the
MNP’s capacity to adsorb the pesticides (i.e., non-aged adsorbed
35% and 69% and UV-aged adsorbed 9.7% and 63% of lindane and DDE,
respectively) likely due to a shift in MNPs hydrophobicity and consequently
reduced the cytotoxicity of the pesticide MNPs mixture. Nanoplastics
induced approximately 20% more lysosomal damage than microplastics,
suggesting a distinct toxicity mechanism. Fluorescently labeled MNPs
accumulated in intestinal cells which confirmed the internalization.
Finally, bioaccumulation of DDE decreased approximately 2 to 8-fold
in cells coexposed with all particle types, although lindane was not
detected in the cells. Overall, our study indicated that MP and NPs
reduce bioavailability of pesticides, but UV aging and particle fragmentation
to nano size increased their bioaccumulation and toxicity in fish
intestinal cells.

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