Pesticide Residue Monitoring on South African Fresh Produce Exported over a 6-Year Period

Results from the Danish monitoring programme on pesticide residues from the period 2012-2017 - frequencies and trends in detected pesticides

In order to assess compliance with maximum residue levels in foods and evaluate the exposure of the Danish population to pesticides, a comprehensive monitoring programme was conducted. The work from 2012-2017 involved testing pesticide residues in fruits, vegetables, cereals, animal product and processed commodities. The sampling strategy, mainly based on exposure calculations and previous findings, involved the collection of 13,492 samples primarily from fresh conventional and organic produces on the Danish market. The origin of the samples varied, with 34% being of Danish origin and 67% originating from EU and non-EU countries. The results revealed that residues in conventionally grown produce were detected in 54% of the fruit and vegetable samples, and 30% of the cereal samples. Additionally, residues above the maximum residue limits were found in 1.8% of these samples, most frequently in fruits. As previous years, more residues were found in samples of foreign origin compared to samples of Danish origin. Compared to earlier findings more than 40 pesticides were detected for the first time and including boscalid, imidacloprid, thiacloprid, etofenprox, and spinosad, all detected more than 100 times. The data shows that detection of PFAS pesticides has increased dramatically, from 24 in 2006 to 412 in 2022.

Interactive transgenerational effects of parental co-exposure to prochloraz and chlorpyrifos: Disruption in multiple biological processes and induction of genotoxicity

The application of different types of pesticides can result in the coexistence of multiple pesticide residues in our food and the environment. This can have detrimental effects on the health of offspring across generations when parents are exposed to these pesticides. Therefore, it is imperative to understand the long-term effects that can be inherited by future generations when assessing the risks associated with pesticides. To study the genotoxic effects of commonly used pesticides, prochloraz (PRO) and chlorpyrifos (CHL), and assess whether their combined exposures have a different toxic effect, we modeled the transgenerational effects of parental (F0-generation) and/or offspring (F1-generation) exposures on zebrafish embryos in the F1-generation. Following the exposures, we proceeded to assess the impacts of these exposures on a range of biological processes in F1-generation zebrafish. Our results revealed that exposure to PRO and CHL altered multiple biological processes, such as inflammation, apoptosis, oxidative stress, and thyroid hormone synthesis, and detoxification system, providing molecular targets for subsequent studies on toxicity mechanisms. Notably, our study also found that the biological processes of F1-generation zebrafish embryos were altered even though they were not exposed to any pesticide when F0-generation zebrafish were exposed to PRO or CHL, suggesting potential genotoxicity. In conclusion, we provided in-vivo evidence that parental exposure to PRO and/or CHL can induce genotoxicity in the offspring. Moreover, we observed that the toxic effects resulting from the combined exposure were interactive, suggesting a potential synergistic impact on the offspring.

Pesticide Residues in Fresh Fruit and Vegetables from Farm to Fork in the Kampala Metropolitan Area, Uganda

This study assessed concentrations of pesticide residues in fruits and vegetables from farm-to-fork in Kampala Metropolitan Area, Uganda. A total of 160 samples of fruit and vegetables collected from farms, markets, streets, restaurants and homes were analysed using liquid chromatography-tandem mass spectrometry; and Gas Chromatograph-Mass Spectrometer for dithiocarbamates. Multiple pesticide residues were detected in majority of the samples (95.6%). The proportions of the most frequently detected pesticides residue classes were organophosphates (91.3%), carbamates (67.5%), pyrethroids (60.0%) dithiocarbamates (48.1%) and neonicotinoids (42.5%). Among organophosphates, propotamophos, acephate, fonofos, monocrotophos and dichlorvos were the most detected active ingredients; aminocarb, methomyl and pirimicarb were the commonly detected carbamates; while imidacloprid, a neonicotinoid and lambda-cyhalothrin, pyrethroid were also highly detected. Twenty-seven pesticide were tested at all stages, of which the concentrations either decreased or increased along the chain. Multiple pesticide residues occurred in commonly consumed fruit and vegetables with decreasing or increasing concentrations from farm-to-fork.

Current use pesticides in soil and air from two agricultural sites in South Africa: Implications for environmental fate and human exposure

Concerns about the possible negative impacts of current use pesticides (CUPs) for both the environment and human health have increased worldwide. However, the knowledge on the occurrence of CUPs in soil and air and the related human exposure in Africa is limited. This study investigated the presence of 30 CUPs in soil and air at two distinct agricultural sites in South Africa and estimated the human exposure and related risks to rural residents via soil ingestion and inhalation (using hazard quotients, hazard index and relative potency factors). We collected 12 soil and 14 air samples over seven days during the main pesticide application season in 2018. All samples were extracted, purified and analyzed by high-performance liquid chromatography coupled with tandem mass spectrometry. In soils, nine CUPs were found, with chlorpyrifos, carbaryl and tebuconazole having the highest concentrations (up to 63.6, 1.10 and 0.212 ng g^-1, respectively). In air, 16 CUPs were found, with carbaryl, tebuconazole and terbuthylazine having the highest levels (up to 25.0, 22.2 and 1.94 pg m^-3, respectively). Spatial differences were observed between the two sites for seven CUPs in air and two in soils. A large dominance towards the particulate phase was found for almost all CUPs, which could be related to mass transport kinetics limitations (non-equilibrium) following pesticide application. The estimated daily intake via soil ingestion and inhalation of individual pesticides ranged from 0.126 fg kg^-1 day^-1 (isoproturon) to 14.7 ng kg^-1 day^-1 (chlorpyrifos). Except for chlorpyrifos, soil ingestion generally represented a minor exposure pathway compared to inhalation (i.e. <5%). The pesticide environmental exposure largely differed between the residents of the two distinct agricultural sites in terms of levels and composition. The estimated human health risks due to soil ingestion and inhalation of pesticides were negligible although future studies should explore other relevant pathways.

Risk Assessment of Pesticide Residues in Chinese Litchis

ABSTRACT

The presence of pesticide residues in fruit has been of extensive concern worldwide. Pesticide residues in 150 litchi samples collected in the People's Republic of China were measured, and the dietary exposure risks to consumers were evaluated. The litchi samples were screened by gas chromatography and ultraperformance liquid chromatography with tandem mass spectrometry for the possible presence of 57 pesticides. Seventeen pesticides were detected, and 70.7% of samples contained residues of one or more pesticides. The most frequently detected pesticide (36% of samples) was diflubenzuron. Carbofuran in one sample exceeded its maximum residue limit by 125%. In dietary exposure assessments, all concentrations below the limit of detection (LOD) were calculated as 0, 0.5 × the LOD, or at the LOD separately, and these assessments indicated that the chronic health risks from these dietary exposures were extremely low. For acute exposures, carbofuran was at 11.08% of the acute reference dose, and all other pesticides were <2% of the acute reference dose. The findings indicated that the presence of pesticide residues in litchis should not be considered a public health problem.

HIGHLIGHTS

A translocation analysis of organophosphate pesticides between surface water, sediments and tissues of common reed Phragmites australis

This study investigated the ability of common reed, Phragmites australis to take up organophosphate pesticides (OPPs). The study site was the agriculturally polluted Sundays Estuary in South Africa. Surface water, leaves, roots, and deep-rooted-sediments of P. australis were collected along the length of the estuary and analysed for 13 different OPPS. The extraction of OPPs in plant tissues was performed by QuEChERS method followed by GC-MS analysis. The highest concentration of OPPs was found in leaves (16.41-31.39 μg kg^-1 dw), followed by roots (13.92-30.88 μg kg^-1 dw), and sediments (3.30-8.07 μg kg^-1 dw). Of the 13 targeted OPPs, only one compound was not detected across the four sample matrices, thus reflecting widespread contamination in the Sundays Estuary. The biota sediment accumulation factor (BSAF) values of pyraclofos, quinalphos, fenitrothion, phosalone, EPN, diazinon, chlorpyrifos, pyrazophos, and isazophos were higher than one implying that P. australis possesses the ability to bioaccumulate these compounds. The root-leaf translocation factors (TF_r-l) of these pesticides were higher than 1, suggesting that P. australis possesses the capacity to move these pesticides from roots to leaves. The insignificant correlation observed between log BSAF and log K_ow and log TF_r-l and log K_ow implies that OPPs uptake by P. australis tissues were not dependent on log Kow. Our study demonstrates that P. australis possesses the potential to effectively remove OPPs from contaminated water and sediment.

Pesticide residues in fruits and vegetables from the southern part of Botswana

This study reports a surveillance of multi-pesticide residues of fruits and vegetables sold in the local markets carried out in 2018-2019 in Botswana to access consumer safety. A validated method for analysis of 232 pesticide residues in fruits and vegetables was applied, based on QuEChERS-GC-MS/MS methodology. A total of 83 fruit and vegetable sold in different markets were bought from three different areas of the southern region . Levels of pesticides ranged between 0.0032 ± 0.0009 mg/kg and 70.4 ± 19.4 mg/kg. A total of 78% of the samples contained pesticide residues, whereas only 13% of the samples violated the EU/Codex MRLs. In particular, rape vegetable samples exceeded legislative limits most, followed by cabbage, green pepper and tomato. The most frequently detected compounds were chlopyrifos, chlorfenapyr, tebuconazole, methamidophos and cypermethrin. These results will serve as a foundation for future studies, involving continuous monitoring programmes.

Qualitative assessment of 27 current-use pesticides in air at 20 sampling sites across Africa

Increasing use of current-use pesticides (CUPs) in Africa raises environmental and public health concerns. But there is a large uncertainty about their occurrence and the composition of pesticide mixtures on this continent. This paper investigates the presence of 27 CUPs in air across 20 sampling sites in Africa. 166 passive air samples, consisting of polyurethane foam (PUF), were collected in 12 African countries between 2010 and 2018. Samples were extracted with methanol and analyzed via high-performance liquid chromatography coupled with tandem mass spectrometry. The detection frequencies of CUPs per site were compared to land use patterns and sampling years, while their similarities were assessed using hierarchical cluster analysis. Overall, 24 CUPs were detected at least once. In 93% of all samples, at least one CUP was detected, while 78% of the samples had mixtures of two or more CUPs (median 3, interquartile range 5). Atrazine and chlorpyrifos were detected in 19 out of 20 sampling sites. Carbaryl, metazachlor, simazine, tebuconazole and terbuthylazine had the highest detection frequencies at sampling sites dominated by croplands. Across all the sampling years, 16 CUPs were present. Seven CUPs were newly detected from 2016 onwards (azinfos-methyl, dimetachlor, chlorsulfuron, chlortoluron, isoproturon, prochloraz and pyrazon), while metamitron was only present before 2012. Sites within a radius of about 200 km showed similarities in detected CUP mixtures across all samples. Our results show the presence of CUP mixtures across multiple agricultural and urban locations in Africa which requires further investigation of related environmental and human health risks.

Micro QuEChERS-based method for the simultaneous biomonitoring in whole blood of 360 toxicologically relevant pollutants for wildlife

This work presents the optimization, validation, and verification of a miniaturized method for the determination of 360 environmental pollutants that are of toxicological concern for wildlife. The method implies a one-step QuEChERS-based extraction of 250 μl whole blood using acidified acetonitrile, followed by two complementary analyses by LC-MS/MS and GC-MS/MS. The optimized conditions allow the simultaneous determination of the major persistent organic pollutants, a wide range of plant protection products, rodenticides, pharmaceuticals, and a suite of metabolites that can be used as biomarkers of exposure. The method is very sensitive, and 95% of the pollutants can be detected at concentrations below 1.5 ng/ml. The method was applied to a series of 148 samples of nocturnal and diurnal wild raptors collected during field ecological studies in 2018 and 2019. Fifty-one different contaminants were found in these samples, with a median value of 7 contaminants per sample. As expected, five of the six contaminants that were detected in >50% of the samples were persistent or semi-persistent organic pollutants. However, it is striking the high frequency of detection of some non-persistent pollutants, such as 2-phenylphenol, benalaxyl, metaflumizone, diphenylamine, brodifacoum or levamisole, indicating the penetration of these chemicals into the food chains. The toxicological significance of all these findings should be studied in depth in future research. However, the results clearly demonstrated that the approach developed provides reliable, simple, and rapid determination of a wide range of pollutants in wildlife and makes it very useful to obtain valuable data in biomonitoring studies with only small amounts of sample.

Selected food processing techniques as a factor for pesticide residue removal in apple fruit

In this study, various food processing techniques, including high-temperature processes (pasteurization/sterilization and boiling), low-temperature processes (freezing), mechanical processing (peeling and juicing), and water-based processes (washing with tap water and ultrasonic washing) were used to identify the most effective way to remove contamination of 5 fungicides (cyprodinil, difenoconazole, fluopyram, tebuconazole, and fludioxonil). The most effective processes were juicing and freezing in the range between 63 and 100% and from 52 to almost 100%, respectively. Ultrasonic washing and boiling also significantly removed pesticide residues ranging from 79 to 84% and from 72 to 78%, respectively. The same trend was observed by peeling process where maximum reduction of 80% was achieved almost for all fungicides. Washing with tap water decreased the concentration levels in the range of 35-38%. This study demonstrated that the least effective and unpredictable method of decontamination of pesticides was sterilization and pasteurization, due to the large variation in pesticide levels during the process.