Minimization of Imidacloprid Residues in Cucumber and Bell Pepper Through Washing with Citric Acid and Acetic Acid Solutions and Their Dietary Intake Assessment

The efficacy of washing strategies in the elimination of fungicide residues and the alterations on the quality of bell peppers

Food safety problems caused by pesticide residues in vegetables have become a top issue to raise public concern. In this study, bell peppers were grown in an experimental field and sprayed with two systemic (azoxystrobin and difenoconazole) and one contact (chlorothalonil) fungicides. Ozone (ozonated water and water continuously bubble with ozone) or conventional domestic (washing with distilled water, detergent, acetic acid, sodium bicarbonate, and sodium hypochlorite solutions) procedures were investigated to identify the most effective way to remove fungicide residues in bell peppers. The residues in the fruits and the washing solutions were determined by solid-liquid extraction with a low-temperature partition (SLE/LTP) and liquid-liquid extraction with a low-temperature partition (LLE/LTP), respectively, and analyzed by gas chromatography. Water continuously bubbled with ozone a concentration of 3 mg L^-1 was the most efficient treatment with removal of fungicides residues ranging from 67% to 87%. However, similar treatment at a lower concentration (1 mg L^-1) did not only efficiently removed fungicide residues (between 53% and 75%) but also preserving the quality of the fruit along a storage time of 13 days. Among the conventional solutions, sodium bicarbonate at 5% showed good efficiency removing between 60% and 81% of the fungicide residues from bell peppers, affecting the color quality of the fruit. Overall, the most affected physicochemical parameters in bell peppers after the treatments were weight loss, color, and vitamin C content.

Exposure Level of Neonicotinoid Insecticides in the Food Chain and the Evaluation of Their Human Health Impact and Environmental Risk: An Overview

Neonicotinoid insecticides (neonics) were the most rapidly growing class of insecticides over the past few decades, and are used mainly for vegetables, fruits, and grains. Although neonics exhibit lower toxicity in mammals and humans compared to traditional insecticides, increasing numbers of studies are demonstrating that neonics may accumulate in the food chain and environmental media. Long-term exposure to neonics may raise potential risks to animals and even to humans. The present report reviews the development, application, and prohibition of neonics in the farmland ecosystem, and summarizes the exposure level and harmful effects of these insecticides in the food chain. In addition, the present review analyzes and summarizes the evaluation of the human health impact and environmental risk of the neonics, and overviews the unresolved problems and future research directions in this field. The aim of the present report was to review the exposure level, potential toxicity, human health impact, and environmental risk assessment of neonics in various media in order to provide reliable technical support for strengthening the environmental and food safety supervision and green pesticide designing.

Unraveling the toxic effects of neonicotinoid insecticides on the thyroid endocrine system of lizards

The widespread use of neonicotinoids has resulted in large residues in the soil, which has a major impact on the lizards that inhabit the soil. Thyroid hormones play an important role in the growth and development of lizards. In this report, we assessed the disrupting effects of thyroid system on lizards after 28 days of continuous exposure to dinotefuran, thiamethoxam, and imidacloprid, respectively. Neonicotinoid insecticides could seriously affect the concentration of T4 in lizard plasma and the conversion of T4 to T3 in the thyroid gland. Specifically, exposure to dinotefuran affected the intake and utilization of iodine in the thyroid gland, resulting in insufficient thyroid function, which in turn lead to thyroid epithelial hyperplasia and follicular volume enlargement by negative feedback. Exposure to thiamethoxam could activate thyroid function, significantly increasing plasma T3 and T4 concentrations and promoting the binding of T3 and thyroid hormone receptors. Imidacloprid exposure could inhibit the secretion of thyroid hormones, leading to down-regulation of thyroid hormone receptors and related phase II metabolic enzyme genes. This study verified that the continuous exposure of neonicotinoids could affect the lizard thyroid endocrine system. The harm of neonicotinoids to reptiles deserved more attention.

Assessing washing methods for reduction of pesticide residues in Capia pepper with LC-MS/MS

The effects of washing treatments on removal rates of some pesticides residues (acetamiprid, chlorpyrifos and formetanate hydrochloride) on pepper were investigated. Method verification was conducted through spiking pepper samples at 0.1, 1.0 and 10.0 × MRL. QuEChERS method produced average recovery of 104.91% with relative standard deviation (RSD) of 13.41%. LOQ values of acetamiprid, chlorpyrifos and formetanate hydrochloride were estimated as 2, 10 and 5 µg/kg, respectively. Capia peppers grown in open fields were sprayed three times with pesticides. Peppers were harvested after 1st, 2nd and 3rd day of the treatments. Then the peppers were subjected to tap water, acetic acid and citric acid washing and ultrasonic cleaning treatments (for 2 and 5 min). Based on three different harvest times and two different washing durations, processing factors (PFs) and reduction rates were calculated for each washing treatment. The residues gradually decreased during washing treatments with increasing process duration. Similarly, a gradual reduction was noted with the progress of harvest times. This in turn corresponded to an increase in PF. Ultrasonic cleaning and citric acid (9%) washing were more effective than the others. Non-systemic pesticides (chlorpyrifos) were more readily removed than the systemic ones (acetamiprid). Similarly, highly soluble pesticides exhibited higher reduction.

Accumulation and toxicity of thiamethoxam and its metabolite clothianidin to the gonads of Eremias argus

The endocrine disrupting effect of pesticides is considered to be an important factor in the decline of reptile populations. The large-scale application of neonicotinoids in the environment poses a potential threat to small farmland lizards Eremias argus. In this study, we evaluated the disruption effects of thiamethoxam and its metabolite clothianidin on the endocrine disruption of Eremias argus during 28 d exposure. Thiamethoxam and clothianidin could accumulate in the testis and ovary. Adequate blood exchange was the main cause of thiamethoxam and clothianidin accumulation in the gonads. The production of clothianidin aggravated the effect of endocrine disruption to lizards. Thiamethoxam/clothianidin exhibited two distinct ways of interfering with the endocrine disruption of the male and female lizards. Thiamethoxam/clothianidin significantly up-regulated the expression of cyp17 and cyp19 genes in the testis, which ultimately led to a significant decrease in testosterone levels and a significant increase in the 17-estradiol concentrations in plasma. The expression of the estrogen receptor gene in the liver was also significantly increased in male lizards. The significant declines in testosterone and prostaglandin D2 levels in the plasma indicated that thiamethoxam and clothianidin could cause androgen deficiency in male lizards. Meanwhile, in female lizards, thiamethoxam/clothianidin increased the expression of hsd17β gene in the ovary, causing an increase in testosterone levels in the plasma and an up-regulation of androgen receptor expression in the liver. The effects of thiamethoxam and clothianidin on male lizards were more pronounced. This study verified the possible endocrine disrupting effects of neonicotinoids and provided a new perspective for the study of global recession of reptiles.

Dissipation, residues, and risk assessment of imidacloprid in Zizania latifolia and purple sweet potato under field conditions using LC-MS/MS

A shortened version of Quick, Easy, Cheap, Effective, Rugged, and Safe method (QuEChERS) for determining the dissipation and residue of imidacloprid present in Zizania latifolia and purple sweet potato was established by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The average recoveries of imidacloprid in the two crops ranged from 82.12 to 113.79%, with relative standard deviation (RSD) of <7.32%. The dissipation dynamics of imidacloprid in Z. latifolia plants and purple sweet potato plants followed first-order kinetics, with half-lives of 3.2-5.5 days in each of sampling locations. The terminal imidacloprid residues in Z. latifolia and purple sweet potato at each of location were <0.005-0.120 mg kg^-1. According to the risk assessment results, both the acute dietary risk quotient and chronic dietary risk quotient values were <1, indicating that imidacloprid is unlikely to pose health risks to humans with normal recommended use. The present study may serve as a valuable reference for the safe and reasonable use of imidacloprid in Z. latifolia and purple sweet potato fields.

Pesticide residue removal in classic domestic processing of tomato and its effects on product quality

This study was undertaken to evaluate the effectiveness of several household practices (washing with water or acidic, alkaline, and oxidizing solutions, and peeling) in minimizing pesticide residue contamination of tomatoes, as well as the impact on the quality of the treated fruit. Tests were performed using two systemic fungicides (azoxystrobin and difenoconazole) and one contact fungicide (chlorothalonil). Solid-liquid extraction with low temperature partition (SLE/LTP) and liquid-liquid extraction with low temperature partition (LLE/LTP) were used to prepare the samples for pesticides determination by gas chromatography. Washing the tomatoes with water removed approximately 44% of chlorothalonil, 26% of difenoconazole, and 17% of azoxystrobin. Sodium bicarbonate (5%) and acetic acid (5%) solutions were more efficient, removing between 32 and 83% of the residues, while peeling removed from 68 to 88% of the pesticides. The washing solutions altered some fruit quality parameters, including acidity and chroma, and also caused weight loss. Acetic acid (0.15 and 5%) and hypochlorite (1%) solutions had the greatest effect on these parameters.

Enantioselective metabolism of triadimefon and its chiral metabolite triadimenol in lizards

Chinese lizards (Eremias argus) were exposed to separated R-(-)-triadimefon, S-(+)-triadimefon and racemic triadimefon to evaluate enantioselective accumulation of triadimefon. After single oral administration of R-(-)-triadimefon, S-(+)-triadimefon and racemic triadimefon, the time-concentration curves in different tissues were found to be different. Triadimefon enantiomers crossed the blood-brain barrier and brain is a main target organ. The residues of triadimefon enantiomers in fat were highest after 24h indicating that fat was the main tissue of accumulation. In racemic triadimefon exposure group, the enantiomer fractions of R-(-)-triadimefon in different tissues showed that the differences between R-(-)-triadimefon and S-(+)-triadimefon were significant in absorption and metabolism, but the differences became smaller in exclusion and accumulation. From the results of mathematical models, S-(+)-triadimefon was absorbed and eliminated faster than R-(-)-triadimefon, and R-(-)-triadimefon was easily distributed in the tissues and more easily converted into its metabolites. Furthermore, among the four enantiomers of triadimenol, SR-(-)-triadimenol produced by S-(+)-triadimefon may have the highest fungicidal activity and the strongest biological toxicity, RR-(+)-triadimenol produced by R-(-)-triadimefon was most likely to bioaccumulate in lizard. Identifying toxicological effects and dose-response relationship of SR-(-)-triadimenol and RR-(+)-triadimenol will help fully assess the risk of TF enantiomers use in the future. The results enrich and supplement the knowledge of the environmental fate of triadimefon enantiomers.

Assessment of different washing treatments to mitigate imidacloprid and acetamaprid residues in spinach

BACKGROUND

Agricultural crops treated with pesticides retain toxic residues that can cause various health disorders upon consumption. The present research project was designed to assess pesticide residues in contaminated spinach (Spinacia oleracea). The efficiency of chemical solutions (acetic acid, citric acid, hydrogen peroxide, sodium chloride and sodium carbonate) of different concentrations (% w/v) along with tap water for the dissolution of pesticide residues in spinach was studied. After various dipping treatments (T0 -T22 ) of treated spinach, imidacloprid and acetamaprid residues were determined by high-performance liquid chromatography (HPLC).

RESULTS

Among the solutions tested, the highest reductions in imidacloprid and acetamaprid residues respectively were 0.92 ± 0.04 mg kg(-1) (83%) and 1.42 ± 0.53 mg kg(-1) (87%) in treatment T6 (10% acetic acid), followed by 0.79 ± 0.01 mg kg(-1) (69%) and 0.86 ± 0.05 mg kg(-1) (71%) in treatment T11 (10% citric acid), while the lowest were 0.30 ± 0.02 mg kg(-1) (27%) and 0.35 ± 0.02 mg kg(-1) (29%) in treatment T20 (4% sodium carbonate). Moreover, treatment T1 (tap water) caused 0.27 ± 0.00 mg kg(-1) (23%) and 0.38 ± 05 mg kg(-1) (27%) elimination of imidacloprid and acetamaprid residues respectively.

CONCLUSION

From these findings it is inferred that acetic acid and citric acid washing treatments can be used along with tap water to minimize pesticide residues in treated vegetables. © 2015 Society of Chemical Industry.

Stereoselective metabolism, distribution, and bioaccumulation brof triadimefon and triadimenol in lizards

In this research, Chinese lizards (Eremias argus) were chosen as laboratory animal to evaluate the stereoselectivity in the processes of metabolism, distribution, and bioaccumulation of triadimefon. A validated chiral high-performance liquid chromatography coupled with triple quadruple mass spectrometry (HPLC-MS/MS) method was developed for determining enantiomers' residues of parent compound triadimefon and its metabolite triadimenol in lizard blood and tissues. Pharmacokinetic results of single-does exposure suggested that S-(+)-triadimefon was metabolized easier than R-(-)-triadimefon, and RR-(+)-triadimenol was the main metabolic product of triadimefon. During the continuous exposure of two dose (40mg/kg(bw)·d and 200mg/kg(bw)·d), enantiomers of triadimefon and triadimenol were detected in all body compartments, with the highest triadimefon concentrations in brain. However, the triadimenol concentrations were not significantly different among the compartments. The concentrations of RS-(+)-triadimenol were negative correlated with concentrations of RR-(+)-triadimenol both in blood (r=-0.775, p=0.024) and liver (r=-0.834, p=0.02) in 200mg/kg(bw)·d group, which indicates that chiral conversion between enantiomers of triadimenol might exist in the metabolic process of triadimefon. In all the processes, the enantiomer fractions (EFs) of R-(-)-triadimefon and RR-(+)-triadimenol were significantly different from their natural ratios, 0.5 and 0.1, respectively, which proved that metabolism, bioaccumulation, and distribution of triadimefon and triadimenol in lizards were enantioselective. These results help enrich and supplement the knowledge of the stereoselective behaviour of triadimefon and triadimenol in reptile.