Simulation of nonylphenol degradation in leafy vegetables using a deuterated tracer

Analysis of Endocrine Disrupting Nonylphenols in Foods by Gas Chromatography-Mass Spectrometry

Nonylphenols (NPs) are classified as endocrine-disrupting chemicals (EDCs), which are known to cause disorders in the endocrine systems of organisms. Due to their high lipophilicity and low degradability, these harmful substances are known to accumulate and persist in the environment, and even enter into the food chain. Analytical methods of liquid-liquid extraction using solid-phase extraction for sample clean-up combined with gas chromatography/mass spectrometry were established to determine the presence of NPs in foods. This study aimed to develop and validate these methods using four food matrices representing high-fat and low-fat solid food, as well as high-fat and low-fat liquid food, groups. The single linear isomer 4-n-NP was used to validate the quantification of NPs, which exist in complex isomer mixtures. Our results showed good linearity, with correlation coefficients exceeding 0.998 for all four matrices. The limits of detection and quantification were 0.37-1.79 and 1.11-5.41 μg/kg, respectively. Recovery rates were 86.8-108.6% and 92.6-101.9% for intraday and interday assays, respectively, and the relative standard deviations (RSDs) were below 12% for both assays. The method was applied to analyze 1185 domestic food samples consumed by Koreans, with NPs detected at concentration ranges of 2.57-269.07 μg/kg. Results for each food type over wide concentration ranges indicated that these compounds are highly dependent on the area of cultivation, and are affected by the levels of those contaminants in different environments. The contents of NPs in foods from animal sources were generally higher than those from plant sources, in particular being higher in the intestines than in lean tissue. The present findings could form the basis for determining the level of dietary exposure to NPs and how each food source contributes to it in South Korea.

Occurrence, uptake, and health risk assessment of nonylphenol in soil-celery system simulating long-term reclaimed water irrigation

Reclaimed water (RW) irrigation provides an effective method to alleviate freshwater resources shortage. However, the residual endocrine disrupting chemicals in RW may cause potential risks to the environment and human body. Pot experiments were conducted to study the occurrence and environmental behavior of nonylphenol (NP) in soil-celery system simulating long-term RW irrigation, and exposure to NP was assessed to identify human health risks. Celery was grown on soil with different initial NP concentrations (0.126-22.9 mg·kg^-1) to simulate the different irrigation years. After harvest, the NP concentrations in roots, stems and leaves were 0.26-1.51, 0.21-0.45 and 0.33-0.74 mg·kg^-1, respectively. The NP concentrations in soil at depths of 5, 10 and 15 cm were 0.047-1.75, 0.088-1.77 and 0.048-1.07 mg·kg^-1, respectively. The results showed a limited NP enrichment capacity of celery and low residual rates of NP in soil-celery system, which were between 6.33% and 26.3%. Both the bioconcentration factors (BCFs) and the residual rates of NP decreased with the initial NP concentrations in soil. The total noncancer hazard quotients (HQs) for human exposure to NP from celery and soil had the order of 10^-4-10^-3, which was lower than the acceptable risk level of 1 and showed safe conditions under long-term RW irrigation.