Neem extract is an alternative insecticide for organic farming and is an allowed component for commercial biopesticide in Korea. However, crop protection properties are not consistent in commercial products. In this report, quantitative analysis of commercial biopesticides for the four insecticidal limonoids of neem extract-azadirachtin A, azadirachtin B, deacetylsalannin and salannin, was conducted through solid phase extraction method with lipophilic-hydrophilic balanced material. The recoveries of the four limonoids ranged from 80.5% to 105%, and their limit of quantitation ranged from 0.028 mg/L to 0.356 mg/L. On the five imported neem extracts, the total contents of the four bioactive limonoids extracted were from 321 mg/L to 5810 mg/L, but there were big variations in the relative composition of the limonoids. The total limonoidal concentrations in 23 commercial bio-pesticides made from neem showed from below LOQ to 7190 mg/L with significant differences in the relative composition. These differences determine the biopesticide's efficacy on pests, therefore, tracking the active ingredients is necessary for the quality control of commercial bio-pesticides.

This study performed the first environmental and dietary exposure assessment to explore plant uptake of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) from agricultural soil and irrigation water in the Nakdong River delta, South Korea. Annual average concentrations of total PFOA and PFOS ranged from 0.026 to 0.112 µg L -1 (irrigation water), and from 0.818 to 1.364 µg kg -1 (soil), respectively. PFOA and PFOS hotspots were identified downstream of the Nakdong River, and were influenced by seasonal climatic variations. The observed average biennial concentration of the sum of PFOA and PFOS decreased in irrigation water, from 0.112 µg L -1 in 2013 to 0.026 µg L -1 in 2015, suggests that the 2013 Persistent Organic Pollutants Control Act may have helped to reduce levels of PFAS at this location. This study calculated some of the highest plant uptake factors reported to date, with values ranging from 0.962 in green onions to < 0.004 in plums. Leafy vegetables and rice are important components of the Korean diet; these groups had the largest contribution to the estimated dietary intake of PFOA and PFOS, which was calculated at 0.449 and 0.140 ng kgbw -1 day -1 , respectively. This corresponded to 66.4% for PFOA and 7.9% for PFOS of the EFSA reference dose (RfD). The dietary intake of PFOA and PFOS from crops alone did not exceed the RfD. However, when the estimated daily intake (EDI) from other sources such as tap water, meat, fish, dairy and beverages were included in the exposure risk assessment, both of the EDIs to PFOA and PFOS exceeded the RfDs, indicating there may be a risk to human health. This study concludes that consumption of crops might, therefore, be a significant and underappreciated pathway for human exposure to PFAS.

Research on the occurrence of perfluorochemicals (PFCs) such as perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in the agricultural environment is lacking, in spite of their potential risk via food chain transfer from aquatic and soil-plant systems to animals and/or humans. In the present study, for the first time, soil and water samples collected from 243 different agricultural sites adjacent to waste water treatment plants (WWTPs) belonging to 81 cities and 5 provinces with different levels of industrialization in South Korea were monitored for concentrations of PFOS and PFOA by use of solid phase extraction and liquid chromatography-tandem mass spectroscopy (LC-MS/MS). Significant mean concentrations of PFOA (0.001-0.007 µg L-1 water and <0.05-1.573 µg kg-1 soil) and PFOS (0.001-0.22 µg L-1 water and <0.05-0.741 µg kg-1 soil) were found in all samples. Concentrations of PFCs in soils were high, highlighting that soil is an important sink for PFCs in the agricultural environment. Samples from near WWTPs in Gyeongsang Province contained the highest concentrations of PFOS and PFOA, reflecting the concentration of heavy industry in the province. The concentrations of PFCs in agricultural water (most samples <0.05 µg L-1) and soils (most samples <1 µg kg-1) from South Korea were less than acceptable guideline values, indicating that South Korea is not a hotspot of PFOS and PFOA contamination and that there is negligible risk to human and ecological health from these chemicals. However, further studies investigating the seasonal variation in PFOA, PFOS and other perfluorochemical concentrations in the agricultural environment are needed.

This study provides a review of methods used in the determination of organochlorine pesticides (OCPs) in ginseng and compares the effectiveness of three extraction methods (Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS), a modified QuEChERS and a Fast Pesticide Extraction (FaPEx)) in the analyses of 20 OCPs in ginseng root samples. For each method, sample mass, solvent volume and sorbent mass were varied to identify the optimum combination to effectively isolate analytes of interest from the complex sample matrix. Extracts were analyzed using the gas chromatography-μ-electron capture detector (GC-μ-ECD), and confirmatory analyses performed by gas chromatography-tandem-mass spectrometry (GC-MS/MS). Eighteen out of 20 OCPs spiked onto in-house prepared ginseng samples produced acceptable recoveries (51–156%) when extracted using QuEChERS and FaPEx. All 20 analytes, including dichlorodiphenyldichloroethane (p, p’- DDD) and dichlorodiphenyltrichloroethane (o, p’-DDT), produced acceptable recoveries (51–129%) with the use of a modified QuEChERS method. The applicability of the modified QuEChERS method was demonstrated through the analysis of ginseng samples grown in endosulfan-treated soil. The samples were analyzed by both GC-μ-ECD and GC-MS/MS with no significant difference identified in the results of each analytical method. This study highlights the applicability of the modified QuEChERS method, in combination with GC- μ-ECD, to determine organochlorine pesticides in ginseng. This may be especially useful for laboratories in developing countries and less advanced institutions without access to MS/MS instrumentation.

This study was conducted to investigate residual organochlorine pesticides in green house soil and oriental melon, green pepper, and lettuce. The majority of them were designated as persistent organic pollutants (POPs) by the international community at the Stockholm Convention on Persistent Organic Pollutant. Extraction and clean-up method were developed using the QuEChERS method for residual organochlorine pesticides (OCPs) in soil and oriental melon, green pepper and lettuce. Recovery of OCPs in greenhouse soil and oriental melon, green pepper, and lettuce ranged from 73.3-110.6%. Limit of detection (LOD) of OCPs in soil and 3 crops were 0.01-0.08 and 0.11-0.17 μg/kg. The residues of OCPs in oriental melon, green pepper and lettuce greenhouse soil were analyzed by the developed method, and dieldrin, β-endosulfan and endosulfan sulfate were detected at 1.4-72.5, 0.1-78.7 and 0.0-214.1 μg/kg, respectively. The detection frequency of 3 compounds in soils were 52 (29.7%), 34 (19.4%) and 57 (32.6%) among 175 samples, respectively. However, these compounds were not detected in all crop samples. The residue level in 3 crops were lower than 1/58.8 of maximum residue level of them. These results showed that the OCPs residue in oriental melon, green pepper, and lettuce greenhouse soil were not as high as crop safety threatening. Key words