Uptake and Metabolism of Phthalate Esters by Edible Plants

Abstract

Phthalate esters (PAEs) are large-volume chemicals and are found ubiquitously in soil as a result of widespread plasticulture and waste disposal. Food plants such as vegetables may take up and accumulate PAEs from soil, potentially imposing human health risks through dietary intake. In this study, we carried out a cultivation study using lettuce, strawberry, and carrot plants to determine the potential of plant uptake, translocation, and metabolism of di-n-butyl phthalate (DnBP) and di(2-ethylhexyl) phthalate (DEHP) and their primary metabolites mono-n-butyl phthalate (MnBP) and mono(2-ethylhexyl) phthalate (MEHP). All four compounds were detected in the plant tissues, with the bioconcentration factors (BCFs) ranging from 0.16 ± 0.01 to 4.78 ± 0.59. However, the test compounds were poorly translocated from roots to leaves, with a translocation factor below 1. Further, PAEs were readily transformed to their monoesters following uptake. Incubation of PAEs and monoalkyl phthalate esters (MPEs) in carrot cell culture showed that DnBP was hydrolyzed more rapidly than DEHP, while the monoesters were transformed more quickly than their parent precursors. Given the extensive metabolism of PAEs to monoesters in both whole plants and plant cells, metabolism intermediates such as MPEs should be considered when assessing human exposure via dietary intake of food produced from PAE-contaminated soils.

Distribution patterns of phthalic acid esters in soil particle-size fractions determine biouptake in soil-cereal crop systems

“…For maize and wheat tissues, especially grains, their BCFs with respect to PAE congeners are far greater than one, indicating the strong PAE enrichment abilities of maize and wheat. The BCFs of PAE congeners in both whole maize and wheat plants are equal to those of herbaceous plants52, but obviously higher than those of vegetables in previous studies8171820, implying the higher PAE enrichment ability of maize and wheat than vegetables.…”

“…Dietary intake from contaminated food is the primary source of PAE exposure in the general population15; according to the model of the European Union System for the Evaluation of Substances (EUSES), the exposure to edible crops can account for 89.9% and 51.0% of the total human intake exposure for dibutyl phthalate (DBP) and DEHP, respectively16. Previous studies reported the occurrence and status of PAEs in the soil-crop system and showed that the accumulations of PAEs in plant tissues are mainly govern by combined factors of organic matter, minerals, pH, temperature and microorganisms of soils and intrinsic physicochemical properties of pollutants81718192021. However, most of these studies were conducted in vegetable crop fields, whereas the dynamics of PAEs in soil–cereal crop systems, particularly the cereal cropping system from actual agricultural fields, remains unclear.…”

Partition and Fate of Phthalate Acid Esters (PAEs) in a Full-Scale Horizontal Subsurface Flow Constructed Wetland Treating Polluted River Water

“…The root-water concentration factor (RWCF, Equation 3) and root-soil concentration factor (RSCF, Equation 4) were calculated as the PAEs level in root to that in water and soil, respectively. The translocation factor (TF, Equation (5)) was calculated as the ratio of PAEs level in leaves to that in roots [6].…”

“…As additives in numerous products, including coatings, coverings, insecticides, flooring, drainpipes, packaging, cosmetics, adhesives, and paints [2], they may migrate into the environment via various pathways including microbial transformation, microsomal metabolism, and sunlight exposure [3]. With strong chemical bond to the matrices of polymers, PAEs are persistent and found in almost all the environments, such as rivers [4], sediments [5], soils [6], sewage [7], air [8], biota [9], and even in human tissue [10]. Many pieces of evidence show the carcinogenic, teratogenic, and estrogenic effects of PAEs [11].…”

A review of measured bioaccumulation data on terrestrial plants for organic chemicals: Metrics, variability, and the need for standardized measurement protocols

“…Endophytic organisms can also contribute to the metabolism of organic chemicals within plants [21]. Plant biotransformation rates are available for a few pesticides [17,22,23], pharmaceutical chemicals [24], and plasticizers [25,26]. Furthermore, plant dissipation rates (degradation and transport loss mechanisms) can vary considerably between different plant compartments and environmental conditions [27,28].…”