How Vegetable Roots and Leaves Absorb and Move Perfluoroalkyl Substances

Jim Crocker
4th August, 2024

How Vegetable Roots and Leaves Absorb and Move Perfluoroalkyl Substances

Image Source: Natural Science News, 2024

Key Findings

  • The study by Huazhong Agricultural University found that radish, which lacks root Casparian strips, transfers PFASs more readily to its leaves compared to pak choi
  • Bioaccumulation of C4-C8 perfluoroalkyl carboxylic acids in pak choi roots follows a U-shaped trend with increasing carbon chain lengths, and their movement to leaves decreases with longer chains
  • Leaf uptake of PFASs, especially PFOA, depends mainly on cuticle sorption, and stomatal activity influences PFAS concentrations in leaves
Perfluoroalkyl substances (PFASs) are synthetic chemicals widely used since the 1940s for their water and oil repellent properties. Unfortunately, their non-biodegradable nature has led to widespread environmental contamination, posing significant risks to human health and ecosystems[2]. Recent research conducted by Huazhong Agricultural University has provided new insights into how these substances are taken up and translocated by crop plants, specifically focusing on pak choi and radish[1]. The study examined the uptake and movement of various PFASs, including perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), and perfluorooctane sulfonate (PFOS), in both the roots and leaves of the crops. Understanding these pathways is crucial for assessing potential human exposure through the food chain. One key finding is that radish, which lacks root Casparian strips—a barrier that regulates the movement of substances into the plant—transfers PFASs more readily to its leaves compared to pak choi. This suggests that root vegetables without Casparian strips could pose a higher risk of PFAS bioaccumulation and subsequent human intake in contaminated environments. The study also revealed that the bioaccumulation of C4-C8 perfluoroalkyl carboxylic acids (PFCAs) in pak choi roots follows a U-shaped trend with increasing carbon chain lengths. Furthermore, the ability of these substances to move from roots to leaves decreases as their chain lengths increase. This is consistent with previous findings that longer-chain PFASs tend to be less mobile within plants[3]. Leaf uptake of PFASs, particularly PFOA, was found to depend mainly on cuticle sorption. Interestingly, the study noted a slight decrease in PFOA concentrations in leaves after stomatal closure, induced by the plant hormone abscisic acid. This indicates that stomatal activity plays a role in PFAS uptake. The translocation of PFASs from exposed leaves to roots and then to unexposed leaves was also observed, with longer-chain PFASs showing higher translocation potentials. PFOS, in particular, demonstrated higher bioaccumulation in both roots and leaves compared to PFOA, attributed to its greater hydrophobicity. These findings build on earlier research that has documented the environmental and health impacts of PFASs[4]. For instance, a study conducted in Fuxin, China, found significant contamination of water and soil with PFASs, leading to detectable levels in human serum[4]. Additionally, research has shown that crops grown in PFAS-contaminated soils can accumulate these substances, potentially entering the human food chain[3]. The current study highlights the importance of plant selection in PFAS-contaminated environments. Root vegetables like radish, which lack protective Casparian strips, should be avoided due to their higher potential for PFAS accumulation and human exposure. This research underscores the need for continued investigation into the mechanisms of PFAS uptake and translocation in plants, which could inform agricultural practices and policies aimed at minimizing human exposure to these persistent pollutants. Understanding the interplay between plant anatomy and PFAS properties is crucial for developing effective strategies to mitigate the risks associated with PFAS contamination. The findings from Huazhong Agricultural University provide valuable insights that could help guide future research and policy decisions in this area.

VegetablesEnvironmentBiochem

References

Main Study

1) Differential uptake and translocation of perfluoroalkyl substances by vegetable roots and leaves: Insight into critical influencing factors.

Published 1st August, 2024

https://doi.org/10.1016/j.scitotenv.2024.175205

Related Studies

2) Removal of per- and poly-fluoroalkyl substances (PFASs) by wetlands: Prospects on plants, microbes and the interplay.

https://doi.org/10.1016/j.scitotenv.2021.149570

3) Perfluoroalkyl acid distribution in various plant compartments of edible crops grown in biosolids-amended soils.

https://doi.org/10.1021/es500016s

4) Perfluorinated compounds in the environment and the blood of residents living near fluorochemical plants in Fuxin, China.

https://doi.org/10.1021/es102610x


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