Pesticide Risk Assessment Research Articles

Fungivorous mites enhance the survivorship and development of stingless bees even when exposed to pesticides

Stingless bees are the largest group of eusocial bees in the world. They play an essential role as crop pollinators and have been considered for inclusion in pesticide risk assessments (RAs). Beyond the mutualism involving stingless bee larvae and fungi, the fungivorous mite Proctotydaeus (Neotydeolus) alvearii proved to be interesting for studies of associations with stingless bees. Their presence is related to colony strength and health, showing a permanent-host-association level. Here, we tested whether the coexistence with P. (N.) alvearii affects stingless bee larvae survivorship and development, including when fed pesticide-dosed food. We chose dimethoate, the reference standard for toxicity tests, and thiamethoxam, widely used in neotropical crops and listed to be reassessed in RAs. Bees associated with the mites showed higher larval survivorship rates, even in the dosed ones, and revealed changes in the developmental time and body size. Our study represents the first approach to stingless bee responses to the coexistence of fungivorous mites inside brood cells, leading us to believe that these mites play a beneficial role in stingless bees, including when they are exposed to pesticides.

Occurrence, spatio-temporal distribution, and human health risk assessment of pesticides in fish along the Ayuquila-Armería River, Mexico

Pesticide usage has contributed to increasing food production; it has also caused them to be found in ecosystems inducing adverse effects on biota. Fish are the most abundant and diverse vertebrates in the world and are of great importance both economically and ecologically. Some fishes are indicators of the environmental quality of aquatic ecosystems and provide insight as to how pollutants might influence public health. The tilapias species can be considered biomonitors because they present little displacement representing the contamination level of a site. This study aimed at three goals: (1) to determine the concentration of 20 pesticides in tilapia muscle in the Ayuquila-Armería basin, (2) to describe the spatiotemporal variation of analytes and (3) to evaluate the risk of consuming contaminated fish. The presence of 11 pesticides was determined. Ametrine, glyphosate and malathion concentrations showed significant differences by season. The risk assessment showed that the consumption of tilapia muscle from the Ayuquila-Armería basin does not represent a risk for the population. Diazinon concentrations were relatively low compared to the other pesticides concentrations, but its toxic characteristics were the ones that most negatively influenced the risk assessment. The results obtained are relevant from the social and economic points of view.

Outcome of the consultation with Member States, the applicant and EFSA on the pesticide risk assessment for amisulbrom in light of confirmatory data on the endocrine disrupting effects

The European Food Safety Authority (EFSA) was asked by the European Commission to provide scientific assistance with respect to the risk assessment for an active substance in light of confirmatory data requested following approval in accordance with Article 6(1) of Directive 91/414/EEC and Article 6(f) of Regulation (EC) No 1107/2009. In this context EFSA's scientific views on the specific points raised during the commenting phase conducted with Member States, the applicant and EFSA on the confirmatory data on the endocrine disrupting effects and their use in the risk assessment for amisulbrom are presented. The current report summarises the outcome of the consultation process organised by the rapporteur Member State Greece and presents EFSA's scientific views and conclusions on the individual comments received.

Risk assessment of honey bee stressors based on in silico analysis of molecular interactions.

A global decline of the honey bee Apis mellifera has been observed in the last decades. This pollinator plays a fundamental role in food production and the economy in Europe. The decline of honey bee colonies is linked to several stressors, including pesticides. The current pesticide risk assessment of honey bees in Europe focuses on lethal effects and lacks reflection on sublethal effects. A better understanding of the consequences that exposure to these chemicals has on honey bees is still needed. In this context, the aim of this European Food Risk Assessment Fellowship Programme fellowship project has been to use in silico methodologies, such as virtual screening, as a first step to identify possible interactions at the molecular level between A. mellifera proteins and pesticide ligands. For this purpose, a docking study of the proteins from A. mellifera and pesticide ligands extracted from online databases has been performed by using the software Autodock Vina. The results obtained were a ranking based on the predicted affinity of the pesticides for specific and non-specific binding sites on bee macromolecules. These results were compared with data obtained from the literature and linked to potential sublethal effects. Finally, a risk assessment analysis of the identified molecular stressors of honey bees was performed. The results of this study are considered a starting point to identify new sources of possible stress for honey bees and thereby contribute to the overall understanding of the honey bee decline.

Traceable and Integrated Pesticide Screening (TIPS), a Systematic and Retrospective Strategy for Screening 900 Pesticides and Unknown Metabolites in Tea.

Pesticide management is a crucial issue for sustainable agriculture and food safety. The high-resolution mass spectrometry (HRMS)-based screening method has become a popular choice to monitor pesticide residues in foods and the environment. Data-independent acquisition (DIA) was the first option allowing for this type of analysis due to the wide compound coverage compared to traditional targeted analysis using triple-quadrupole tandem mass spectrometry (QqQ). However, a higher false-positive detection rate is a critical shortcoming in DIA. To overcome this concern, a rigorous method is needed to determine the reliable information acquired from DIA screening. A systematic strategy, traceable and integrated pesticide screening (TIPS), was proposed in this study to comprehensively monitor pesticides and metabolites in a complex tea matrix, avoiding false-positive detection. A total of 900 pesticides were added to an in-house database and evaluated through precision tests, which showed good repeatability and reproducibility. One hundred pesticides and metabolites were detected and confirmed by TIPS in 98 commercial tea samples. In addition to the authorized pesticides that could be detected in TIPS, chlorfluazuron, diafenthiuron, and tolfenpyrad, which are pesticides not allowed to be used in tea farming, were frequently found in this study. In addition, dinotefuran DN and fenbuconazole metabolites RH-9129 and/or RH-9130 were tentatively identified in the archived data using retrospective analysis. The HRMS-based data in TIPS could be a record platform for tracing novel or emerging contaminants not initially targeted in samples. TIPS, a novel strategy, has great potential for rapidly conducting a risk assessment of unexpected pesticides in food.

Cytotoxicity Mechanisms of Eight Major Herbicide Active Ingredients in Comparison to Their Commercial Formulations.

Commercial pesticide formulations contain co-formulants, which are generally considered as having no toxic effects in mammals. This study aims to compare the toxicity of 8 major herbicide active ingredients-namely glyphosate, dicamba, 2,4-D, fluroxypyr, quizalofop-p-ethyl, pendimethalin, propyzamide and metazachlor-with a typical commercial formulation of each active ingredient. Cytotoxicity and oxidative stress capability was assessed in human hepatoma HepG2 cells. Using an MTT assay, formulations of glyphosate (Roundup Probio), fluroxypyr (Hurler), quizalofop-p-ethyl (Targa Super) and dicamba (Hunter) were more toxic than the active ingredient alone. Metazachlor and its formulation Sultan had similar cytotoxicity profiles. Cytotoxicity profiles were comparable in immortalised human fibroblasts. Toxilight necrosis assays showed the formulation of metazachlor (Sultan50C) resulted in significant membrane disruption compared to the active ingredient. Generation of reactive oxygen species was detected for glyphosate, fluroxypyr, pendimethalin, quizalofop-p-ethyl, the formulation of 2,4-D (Anti-Liserons), and dicamba and its formulation Hunter. Further testing of quizalofop-p-ethyl and its formulation Targa Super in the ToxTracker assay system revealed that both products induced oxidative stress and an unfolded protein response. In conclusion, these results show that most herbicide formulations tested in this study are more toxic than their active ingredients in human tissue culture cell model systems. The results add to a growing body of evidence, which implies that commercial herbicide formulations and not just their active ingredients should be evaluated in regulatory risk assessment of pesticides.

Identifying wild bee visitors of major crops in North America with notes on potential threats from agricultural practices

Considering the critical importance of insect pollination to food security and documented declines in wild bee populations, it is imperative to develop effective conservation and management strategies that promote the health of wild bee communities associated with agroecosystems. Identifying wild bee visitors of crops, including crop-flower visitors and species that nest within cropping areas, may prove critical to this endeavor as optimal conservation strategies may differ among bee species and/or guilds, regions, and cropping systems. Although lists of bee species that are associated with North American crops are scattered throughout the literature, there is a need for a comprehensive compilation of those species by crop, region, and nesting guild. Here, we searched the literature to compile a list of wild bee species associated with 33 major crops in North America and assessed the overlap in bee species communities among crops and regions. Of the 739 crop-associated bee species retrieved, 405 species (54.8%) were ground nesters, and 438 species (59.3%) were identified as crop-flower visitors of at least one crop. Because of their nesting and foraging behavior, we argue that these species are more likely to be exposed to agricultural pesticide residues than bee species that do not nest in the ground or feed directly on crop flowers. We further compiled lists of wild bees that have been found to be associated with all of the four most surveyed perennial fruit crops (apple, blueberry, cranberry, strawberry) and all of the three most surveyed cucurbit crops (cucumber, Cucurbita, watermelon) in eastern North America. These lists of bee species can be used to focus attention on species needing better protection strategies within agroecosystems, especially for these two important North American crop groups and can also inform the development of multi-species pesticide risk assessment schemes.

Pollution status and primary risk assessment of eight pesticides in coastal waters around Ishigaki Island, Japan

Ishigaki Island is a remote island in Okinawa Prefecture, Japan, with highly biodiverse ecosystems. Agriculture is one of the most important industries on Ishigaki Island; however, information about pesticide pollution on the island remains limited. Herein, we selected the eight most popular pesticides used in Okinawa Prefecture and investigated their occurrence in the coastal waters of the island; testing was performed four times from May 2020 to March 2021. In addition, we estimated the predicted no-effect concentrations (PNECs) using probabilistic approaches based on the toxicity values obtained from the ECOTOX database of the United States Environmental Protection Agency. The maximum concentrations of dichlorophenoxyacetic acid (2,4-D), bromacil, dichlorvos (DDVP), diazinon, diuron, methidathion (DMTP), fipronil, and metribuzin were 54, 46, 90, 390, 18, 3, 60, and 16 ng/L, respectively. The measured pesticide concentration levels on the island correlated with those previously reported in other areas. Pesticide concentrations were high at the mouths of rivers and decreased with increasing distance in the offshore direction until they were almost undetectable at approximately 1,000 m away. Our results suggest that agricultural runoff was the likely source of pesticides, which then entered coastal areas via rivers. Contamination was limited to the shorelines of Ishigaki Island. Further, the maximum concentrations of diazinon, diuron, and fipronil were higher than the PNECs. The maximum concentrations of DDVP and diazinon were higher than the European Union water quality standards. Our results suggest that these pesticides pose an ecological risk to the coastal environment around Ishigaki Island. This study is the first to evaluate the spatiotemporal distributions and conduct a primary ecological risk assessment of multiple pesticides in the coastal waters of Okinawa Prefecture. These results contribute to both ecosystem conservation and the agricultural industry on Ishigaki Island.

A Discussion on the Transparency and Citizen Participation of Pesticide Risk Assessment from the Controversy of Glyphosate

A Discussion on the Transparency and Citizen Participation of Pesticide Risk Assessment from the Controversy of Glyphosate

Peer review of the pesticide risk assessment of the active substance Cydia pomonella granulovirus (CpGV).

The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State Germany and co-rapporteur Member State theNetherlands for the pesticide active substance Cydia pomonella granulovirus (CpGV) and the considerations as regards the inclusion of the substance in Annex IV of Regulation (EC) No 396/2005 are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012, as amended by Commission Implementing Regulation (EU) No 2018/1659. The conclusions were reached on the basis of the evaluation of the representative uses of CpGV as an insecticide on pome fruit (apple, pear, quince, nashi pears, medlars), stone fruit (peach, apricot, nectarine, almond, plum trees), walnut trees (field foliar spray applications, professional and non-professional uses). The reliable end points, appropriate for use in regulatory risk assessment are presented. Missing information identified as being required by the regulatory framework is listed.

Peer review of the pesticide risk assessment of the active substance aluminium silicate calcined (kaolin calcined).

The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State Greece and co-rapporteur Member State France for the pesticide active substance aluminium silicate calcined (kaolin calcined) and the considerations as regards the Article 12 MRL review of Regulation (EC) No 396/2005 are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012, as amended by Commission Implementing Regulation (EU) No 2018/1659. The conclusions were reached on the basis of the evaluation of the representative uses of aluminium silicate calcined (kaolin calcined) as an insect repellent via broadcast spray application on grapevine, apricot tree, almond tree, cherry tree, hazel tree, walnut tree, peach tree, apple tree, pear tree, quince tree, nashi tree, plum tree, citrus tree, lavender, lavandin and olive tree, as proposed by the applicants. The reliable endpoints, appropriate for use in regulatory risk assessment are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are reported where identified.

Distribution characteristics, sources, and risk assessment of organochlorine pesticides in the Fildes Peninsula and Adelaide Island

This work analyzed the distribution characteristics, sources, and corresponding environmental risks of 10 organochlorine pollutants (OCPs) in soil samples from 13 stations on the Fildes Peninsula and Adelaide Island in Antarctica in 2020. Results showed that the total amount of OCP residues in the study area ranged from N.D. to 2.66 ng·g−1 with an average concentration of 0.90 ng·g−1. Six organochlorine pesticides were detected, and the residue level of DDTs was slightly lower than that of HCHs. The residues of HCHs were mainly γ-HCH and those of DDTs were mainly O, P′-DDT. Source analysis revealed that the residues mainly originated from atmospheric transport and human activities. Environmental risk analysis showed that in the study area, the residues of HCHs and DDTs were present at low levels, and their ecological risk was low.

Pesticide soil microbial toxicity: setting the scene for a new pesticide risk assessment for soil microorganisms (IUPAC Technical Report)

Abstract Pesticides constitute an integral part of modern agriculture. However, there are still concerns about their effects on non-target organisms. To address this the European Commission has imposed a stringent regulatory scheme for new pesticide compounds. Assessment of the aquatic toxicity of pesticides is based on a range of advanced tests. This does not apply to terrestrial ecosystems, where the toxicity of pesticides on soil microorganisms, is based on an outdated and crude test (N mineralization). This regulatory gap is reinforced by the recent methodological and standardization advances in soil microbial ecology. The inclusion of such standardized tools in a revised risk assessment scheme will enable the accurate estimation of the toxicity of pesticides on soil microorganisms and on associated ecosystem services. In this review we (i) summarize recent work in the assessment of the soil microbial toxicity of pesticides and point to ammonia-oxidizing microorganisms (AOM) and arbuscular mycorrhizal fungi (AMF) as most relevant bioindicator groups (ii) identify limitations in the experimental approaches used and propose mitigation solutions, (iii) identify scientific gaps and (iv) propose a new risk assessment procedure to assess the effects of pesticides on soil microorganisms.

Evaluation of temperature corrections for pesticide half-lives in tropical and temperate soils.

Temperature is a key factor that influences pesticide degradation. Extrapolating degradation half-lives (DT50) measured at a given temperature to different temperatures remains challenging, especially for tropical conditions with high temperatures. In this study, the use of the standard Arrhenius equation for correcting temperature effects on pesticide degradation in soils was evaluated and its performance was compared with that of alternative Arrhenius-based equations. To do so, a database of 509 DT50 values measured between 5 and 35°C for 32 pesticides on tropical and temperate soils was compiled for the first time through an extensive literature search. The temperature correction models were fitted to the database using linear mixed regression approaches that included soil type and compound effects. No difference in the temperature dependence of DT50 between tropical and temperate soils was detected, regardless of the model. A comparison of the prediction performances of the models showed that constant activation energy (Ea) cannot be considered valid for the whole range of temperatures. The classical Arrhenius equation with an Ea of 65.4kJ.mol-1, as recommended by the European Food Safety Authority (EFSA), was shown to be valid for correcting the DT50 only for temperatures ranging from 5 to 20°C. However, for temperatures greater than 20°C, which are common in tropical environments, the median Ea was significantly lower at 10.3kJ.mol-1. These findings suggest the need to adapt the standard temperature correction of the European pesticide risk assessment temperature procedure when it is applied in tropical settings.

Complementary biological and computational approaches identify distinct mechanisms of chlorpyrifos versus chlorpyrifos-oxon-induced dopaminergic neurotoxicity.

Organophosphate (OP) pesticides are widely used in agriculture. While acute cholinergic toxicity has been extensively studied, chronic effects on other neurons are less understood. Here, we demonstrated that the OP pesticide chlorpyrifos (CPF) and its oxon metabolite are dopaminergic neurotoxicants in Caenorhabditis elegans. CPF treatment led to inhibition of mitochondrial complex II, II + III, and V in rat liver mitochondria, while CPF-oxon did not (complex II + III and IV inhibition observed only at high doses). While the effect on C. elegans cholinergic behavior was mostly reversible with toxicant washout, dopamine-associated deficits persisted, suggesting dopaminergic neurotoxicity was irreversible. CPF reduced the mitochondrial content in a dose-dependent manner and the fat modulatory genes cyp-35A2 and cyp-35A3 were found to have a key role in CPF neurotoxicity. These findings were consistent with in vitro effects of CPF and CPF-oxon on nuclear receptor signaling and fatty acid/steroid metabolism observed in ToxCast assays. Two-way hierarchical analysis revealed in vitro effects on estrogen receptor, pregnane X receptor, and peroxisome proliferator-activated receptor gamma pathways as well as neurotoxicity of CPF, malathion, and diazinon, whereas these effects were not detected in malaoxon and diazoxon. Taken together, our study suggests that mitochondrial toxicity and metabolic effects of CPF, but not CPF-oxon, have a key role of CPF neurotoxicity in the low-dose, chronic exposure. Further mechanistic studies are needed to examine mitochondria as a common target for all OP pesticide parent compounds, because this has important implications on cumulative pesticide risk assessment.

Dynamic prediction of effective runoff sediment particle size for improved assessment of erosion mitigation efficiency with vegetative filter strips

The most widely implemented mitigation measure to reduce transfer of surface runoff pesticides and other pollutants to surface water bodies are vegetative filter strips (VFS). The most commonly used dynamic model for quantifying the reduction by VFS of surface runoff, eroded sediment, pesticides and other pollutants is VFSMOD, which simulates reduction of total inflow (∆Q) and of incoming eroded sediment load (∆E) mechanistically during the rainfall-runoff event. These variables are subsequently used to calculate the reduction of pesticide load by the VFS (∆P). Since errors in ∆Q and ∆E propagate into ∆P, for strongly-sorbing compounds an accurate prediction of ∆E is crucial for a reliable prediction of ∆P. The most important incoming sediment characteristic for ∆E is the median particle diameter (d50). Current d50 estimation methods are simplistic, yielding fixed d50 based on soil properties and ignoring specific event characteristics and dynamics. We derive an improved dynamic d50 parameterization equation for use in regulatory VFS scenarios based on an extensive dataset of 93 d50 values and 17 candidate explanatory variables compiled from heterogeneous data sources and methods. The dataset was analysed first using machine learning techniques (Random Forest, Gradient Boosting) and Global Sensitivity Analysis (GSA) as a dimension reduction technique and to identify potential interactions between explanatory variables. Using the knowledge gained, a parsimonious multiple regression equation with 6 predictors was developed and thoroughly tested. Since three of the predictors are event-specific (eroded sediment yield, rainfall intensity and peak runoff rate), predicted d50 vary dynamically across event magnitudes and intensities. Incorporation of the improved d50 parameterization equation in higher-tier pesticide assessment tools with VFSMOD provides more realistic quantitative mitigation in regulatory US-EPA and EU FOCUS pesticide risk assessment frameworks. The equation is also readily applicable to other erosion management problems.

Appraisal and risk assessment of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs) in wastewater irrigated area

Appraisal and risk assessment of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs) in wastewater irrigated area

Occurrences, distribution and risk assessment of polar pesticides in Niger River valley and its tributary the Mekrou River (Niger Republic).

The increase in food needs due to high population growth in Niger has led to the intensification of urban agriculture and the increased use of pesticides. The objective of this study is primarily to assess the polar pesticide contamination (mainly herbicides) of the Niger River and its tributary, the Mekrou River, in Niger, using both grab sampling and POCIS (Polar Organic Chemical Integrative Samplers), and then to evaluate the risk to the aquatic environment. Two water sampling campaigns were carried out during the wet and dry seasons. The polar pesticides were analyzed by liquid chromatography coupled with tandem mass spectrometry, which allowed the identification of compounds with concentrations in the grab samples above the WHO guide values and the EU directive: diuron with 2221ng/L (EU quality guideline: 200ng/L), atrazine with 742ng/L (EU quality guideline: 600ng/L) and acetochlor with 238ng/L (EU quality guideline: 100ng/L). The risk assessment study indicated that diuron and atrazine present a high risk for the aquatic environment during the wet season. The main source of water contamination is the intensive use of pesticides in urban agriculture near the city of Niamey, and the intensive cotton farming in the Benin. Moreover, the surveys (30 producers interviewed) showed that 70% of the pesticides used are not approved by the Interstate Committee for Drought Control in the Sahel (CILSS) and some are prohibited in Niger. The inventory of pesticides sold in the zone showed that active ingredients used by producers are 48% insecticides, 45% herbicides, and 7% fungicides.

Intra-specific variation in sensitivity of Bombus terrestris and Osmia bicornis to three pesticides

There is growing evidence that pesticides may be among the causes of worldwide bee declines, which has resulted in repeated calls for their increased scrutiny in regulatory assessments. One recurring concern is that the current frameworks may be biased towards assessing risks to the honey bee. This paradigm requires extrapolating toxicity information across bee species. Most research effort has therefore focused on quantifying differences in sensitivity across species. However, our understanding of how responses to pesticides may vary within a species is still very poor. Here we take the first steps towards filling this knowledge gap by comparing acute, lethal hazards in sexes and castes of the eusocial bee Bombus terrestris and in sexes of the solitary bee Osmia bicornis after oral and contact exposure to the pesticides sulfoxaflor, Amistar (azoxystrobin) and glyphosate. We show that sensitivity towards pesticides varies significantly both within and across species. Bee weight was a meaningful predictor of pesticide susceptibility. However, weight could not fully explain the observed differences, which suggests the existence of unexplored mechanisms regulating pesticide sensitivity across bee sexes and castes. Our data show that intra-specific responses are an overlooked yet important aspect of the risk assessment of pesticides in bees.

Human health risk assessment of pesticides in lettuce and spinach grown in urban backyard garden soils

Pesticide residues in lettuce and spinach could be a serious human health concern since the average per capita consumption per day of leafy salad vegetables is ∼60 g. Here, we determined the leftover residues (LoR) of dimethoate, 2,4-D, glyphosate, and chlorothalonil in lettuce and spinach grown in three urban backyard soils to assess their potential human health hazards. Pesticide residues were extracted by QuEChERS method and quantified through LC-MS and LC-DAD. In most cases, residue levels in the vegetable samples were above the EU-MRLs. Soil organic carbon, silt, oxides of iron and aluminium negatively correlated (P < 0.05) with LoR of the pesticides while LoR positively correlated (P < 0.05) with contents of sand and clay, and pH. The estimated short-term intake (ESTI) values (mg kg1 day1) for dimethoate, 2,4-D, glyphosate and chlorothalonil even at recommended doses in case of lettuce and spinach were 0.003–9.90 × 103 and 0.005–37.10 × 103 for adults and children, respectively, whereas the corresponding estimated daily intake (EDI) values were 0.007–9.58 × 103 and 0.03–35.90 × 103. Accordingly, the calculated values of non-cancer acute health hazard (aHI <100%) and hazard quotient (HQ <1) indicated that consumption of salad vegetables grown in soils spiked with pesticides at doses recommended in agriculture does not pose human health risks. On the other hand, both lettuce and spinach grown in soils at ten-fold higher concentrations of dimethoate or chlorothalonil exceeded the threshold limit of aHI (>100%) for children and HQ > 1 for both children and adults, suggesting their potential acute and chronic health hazards. The present study, for the first time, provides health awareness about the consumption of pesticide-contaminated leafy vegetables grown in urban backyard garden soils.