# Polyethylene Nanoplastics Intensify Arsenic Toxicity in Lettuce by Altering Arsenic Accumulation and Stress Pathways

## TL;DR

Polyethylene nanoplastics increase arsenic toxicity in lettuce by boosting arsenic accumulation in leaves and reducing plant health.

## Contribution

This study reveals that nanoplastics enhance arsenic transfer to edible plant parts and worsen toxicity in agricultural soils.

## Key findings

- Polyethylene nanoplastics increased leaf arsenic by 35–39% and reduced biomass by up to 30%.
- Metabolomic changes indicated disrupted carbon metabolism and antioxidant pathways in treated plants.
- Nanoplastics altered rhizosphere conditions, reducing water content while buffering soil acidification.

## Abstract

Nanoplastics (NPs) are increasingly detected in agricultural soils, yet their influence on arsenic (As) transfer and plant toxicity remains unclear. Lettuce (Lactuca sativa L.) was cultivated in farmland soil with a naturally high As background (98.8 mg·kg−1) to assess how polyethylene nanoplastics (PE NPs) affect rhizosphere conditions, As accumulation, and plant performance. PE NPs partially buffered soil acidification but reduced rhizosphere water content, while total soil As remained largely unchanged. Leaf As increased by 35–39%, with reduced biomass (up to 30%) and lower chlorophyll status (SPAD ~7% lower). Metabolomic analyses indicated dose-dependent alterations in central carbon metabolism and phenylalanine-related antioxidant metabolites, including suppressed tricarboxylic acid cycle intermediates at higher PE levels. Overall, PE NPs enhanced transfer of background As to edible leaves and intensified phytotoxicity, underscoring the need to consider nanoplastics in risk assessment of As-affected soils.