Ecological Risk Assessment Of Pesticides Research Articles

Effect of chlorpyrifos-exposure on the expression levels of CYP genes in Daphnia magna and examination of a possibility that an up-regulated clan 3 CYP, CYP360A8, reacts with pesticides.

Daphnia magna is a test organism used for ecological risk assessments of pesticides, but little is known about the expression levels of cytochrome P450s (CYP)s and their changes after pesticide exposure in the less than 24-h-olds used for ecotoxicity tests. In this study, D. magna juveniles were exposed to 0.2 μg/L of chlorpyrifos under the conditions for acute immobilization test as specified by the OECD test guideline for 24 h, and then the gene expression was compared between the control and chlorpyrifos-exposure groups by RNA-sequencing analysis, with a focus on CYP genes. Among 38 CYP genes expressed in the control group, seven were significantly up-regulated while two were significantly down-regulated in the chlorpyrifos-exposure group. Although the sublethal concentration of chlorpyrifos did not change their expression levels so drastically (0.8 < fold change < 2.6), CY360A8 of D. magna (DmCYP360A8), which had been proposed to be responsible for metabolism of xenobiotics, was abundantly expressed in controls yet up-regulated by chlorpyrifos. Therefore, homology modeling of DmCYP360A8 was performed based on the amino acid sequence, and then molecular docking simulations with the insecticides that were indicated to be metabolized by CYPs in D. magna were conducted. The results indicated that DmCYP360A8 could contribute to the metabolism of diazinon and chlorfenapyr but not chlorpyrifos. These findings suggest that chlorpyrifos is probably detoxified by other CYP(s) including up-regulated and/or constitutively expressed one(s).

Environmental carrying capacity and ecological risk assessment of pesticides under different soil use types in the Central Plains Urban Agglomeration (CPUA), China

Soil environmental safety has received much attention during the past few decades due to its significance in agricultural production and human health. Special attention is required for soil pesticide residues and ecological risks. This study examined 197 soil samples from industrial, residential and agricultural areas for the presence of 12 organophosphorus pesticides (OPPs) and 8 synthetic pyrethroids (SYPs) in the 16 cities in Henan Province, and the center of CPUA, based on the Central Plains Urban Agglomeration (CPUA) concept proposed by China. The total average concentrations of ∑12OPPs in industrial, residential and agricultural soils were 194, 217, 267 ng/g dry weight, and those of ∑8SYPs were 26.8, 35.7, 25.5 ng/g dry weight, respectively. The two pollutants with the greatest concentrations in the soils were malathion and fenpropathrin, respectively, the dominant components of OPPs and SYPs. The soil environmental carrying capacity (SECC) analysis, representing the maximum residual load that can be supported, shows that acephate and cyhalothrin were overloaded, with a predicted period of over 500 years. Among the 16 cities of CPUA, a higher frequency of high ecological risk could be observed only in Shangqiu. The OPPs in children had total non-carcinogenic risk values of more than 1.0. Similarly, the non-carcinogenic risks of SYPs in adults and children in the residential areas were more than 1.0. The study provides knowledge on how to effectively manage soil safety in Henan Province, which is the center of the CPUA, with a large population and grain province to protect ecosystems and reduce the risks of soil pesticide residues in humans.

Ecological risk assessment of pesticides based on earthworms in soils on the southeast slopes of Mount Cameroon

Agrochemicals misuse is common in developing countries with many environmental implications. This work assessed the ecological risk of pesticides, including insecticides, fungicides and herbicides based on earthworms in soils at the lower slopes of Mount Cameroon using the Pesticide Risk in the Tropics to Man, Environment and Trade (PRIMET) model. PRIMET was developed in 2008 in The Netherlands for use in tropical regions. Data on usage scheme and ecotoxicological information were collected and keyed into PRIMET for three main outputs: Predicted Environmental Concentration (PEC), No Effect Concentration (NEC), and Exposure Toxicity Ratio (ETR = PEC/NEC). Pesticides predicted for no acute and no chronic risk to earthworms included fipronil and chlorothalonil. Several pesticides were predicted for an acute risk to earthworms, and they comprised acetamiprid, imidacloprid, lambda-cyhalothrin, and carbendazim when used on maize (PEC ​= ​2.69 ​mg ​kg−1; ETR ​= ​5) and tomato (PEC ​= ​16.15 ​mg ​kg−1; ETR ​= ​30); 2, 4-D and abamectin when used on tomato and ethoprophos. Insecticides exhibiting a possible chronic risk to earthworms comprised acetamiprid, cypermethrin, emamectin benzoate, imidacloprid, indoxacarb, lambda-cyhalothrin, oxamyl, and thiametoxam. The majority of fungicides assessed (83%) posed a possible chronic terrestrial risk, with carbendazim at the top position when applied on tomato (PEC ​= ​16.15 ​mg ​kg−1; ETR ​= ​81). Some herbicides predicted for possible chronic risk based on earthworms included 2, 4-D, diuron, glyphosate, ethoprophos, and metaldehyde. Pesticides with the highest risk to earthworms comprised chlorpyrifos-ethyl, imidacloprid, ethoprophos, and nicosulfuron. The riskiest pesticides should hereby be regulated or replaced by less risky ones. The measurement of pesticide residues in water and food in the various agroecological zones of Cameroon is necessary to shed more light on pesticide ecotoxicology.

Ecological risk assessment of pesticides on soil biota: An integrated field-modelling approach

Pesticide residues in soils can cause negative impacts on soil health as well as soil biota. However, research related to the toxicity and exposure risks of pesticides to soil biota are scarce, especially in the North China Plain (NCP) where pesticides are intensively applied. In this study, the occurrence and distribution of 15 commonly used pesticides in 41 fields in Quzhou county in the NCP were determined during the growing season in 2020. The ecological risks of pesticides to the soil biota, including earthworms, enchytraeids, springtails, mites and nitrogen mineralization microorganisms, were assessed using toxicity exposure ratios (TERs) and risk quotient (RQ) methods. Based on pesticide detection rates and RQs, pesticide hazards were ranked using the Hasse diagram. The results showed that pesticides were concentrated in the 0–2 cm soil depth. Chlorantraniliprole was the most frequently detected pesticide with a detection rate of 37%, while the highest concentration of 1.85 mg kg−1 was found for carbendazim in apple orchards. Chlorpyrifos, carbendazim and imidacloprid posed a chronic exposure risk to E. fetida, F. candida and E. crypticus with the TERs exceeding the trigger value. Pesticide mixtures posed ecological risks to soil biota in 70% of the investigated sites. 47.5% of samples were ranked as high-risk, with the maximum RQ exceeding 490. According to the Hasse diagram, abamectin, tebuconazole, chlorantraniliprole and chlorpyrifos were ranked as the most hazardous pesticides for soil biota in the study region, indicating that alternative methods of pest management need to be considered. Therefore, practical risk mitigation solutions are recommended, in which the use of hazardous pesticides would be replaced with low-risk pesticides with similar functions from the Hasse diagram, or with biopesticides.

Ecological risk assessment of pesticides in the Ngouoh Ngouoh watershed of the Foumbot Municipality in the west region of Cameroon using the PRIMET model.

The use of pesticides near water bodies poses significant risks to non-target organisms. This work aimed at assessing risks related to pesticide utilization on common tropical crops along the Ngouoh Ngouoh stream (West Cameroon) using PRIMET (Pesticide Risks in the Tropics to Man, Environment, and Trade), a pesticide risk model. Data on the physicochemical and ecotoxicological characteristics of pesticides, pesticides application scheme and water abiotic variables were measured and input one at the time into the PRIMET model to get the PEC (Predicted Exposure Concentration), PNEC (Predicted No Effect Concentration) and ETR (Exposure Toxicity Ratio = PEC/PNEC). Among the 13 pesticides assessed, the PRIMET model predicted 8 pesticides to pose acute risk while two were predicted for a chronic risk. Imidacloprid (PEC = 4.53µg/L; ETR = 7.6), mancozeb (PEC = 4.05µg/L; ETR = 5.6), copper hydroxide (PEC = 4.05µg/L; ETR = 23.81), chlorothalonil (PEC = 2.59µg/L; ETR = 15.2) posed a possible acute hazard risk while cypermethrin (PEC = 4.52µg/L; ETR = 7694), emamectin benzoate (PEC = 3.17µg/L; ETR = 317), paraquat (PEC = 33.13µg/L; ETR = 1440) and lambda-cyhalothrin (PEC = 4.52µg/L; ETR = 2.83E + 04) posed definite risks. Cypermethrin also posed a possible chronic hazard to fish (ETR = 32.8) and lambda-cyhalothrin posed a possible risk to daphnia (ETR = 2.7). The Ngouoh Ngouoh stream physicochemical properties exhibited significant changes across sampling stations. Decision-makers should take measures to limit the use of pesticides that are harmful for aquatic biodiversity.

Ecological risk assessment of pesticides in sediments of Pampean streams, Argentina

After their application in agricultural areas, pesticides are dispersed throughout the environment, causing contamination problems. In Argentina, the main promoter of transgenic biotechnology in the region, the total consumption of agrochemicals has increased significantly in recent years. Most chemicals dumped near surface waters eventually end up in bottom sediments and can be toxic to the organisms that live there. However, published data on the mixing of pesticides in this compartment is still scarce. The objective of this work was to detect and quantify pesticide residues in the sediment of rural streams in the Pampas region and to carry out acute and chronic risk assessment in these aquatic ecosystems. The study area comprises the mountainous system of Tandilia, located in one of the most productive agricultural areas in the country. The concentration of atrazine, acetochlor, chlorpyrifos, cypermethrin, and 2,4-D in the sediment of four rural streams was determined in three different seasons, and the toxic units (TU) and the risk ratios (RQ) were calculated. All the compounds analyzed were detected in most of the sampling seasons and study sites, at concentrations higher than those established in the national and international quality guidelines for the protection of aquatic biota in surface waters and for human consumption. Chlorpyrifos, cypermethrin, and acetochlor were the main pesticides contributing to the TU and RQ values, representing a medium or high ecological risk in most of the sites. Therefore, the evaluation of these pesticides in the bottom sediments could be a decisive factor in assessing the risk to the aquatic environment.

Insights into the combined toxic impacts of phoxim and deltamethrin on the embryo-larval stage of zebrafish (Danio rerio)

BackgroundPesticides are usually applied as mixtures, and their joint impacts can generate substantial toxicity to organisms. Although exposures to chemical pesticide mixtures make up most occurrences of pesticide exposures, minimal concern has been given to their combined toxicity and interplays to date. In the present study, endpoints of multiple levels were determined to examine the combined toxic impacts of phoxim and deltamethrin on zebrafish (Danio rerio).ResultsOur study showed that the LC50 values of phoxim obtained over a 96-h exposure period for D. rerio during different life stages ranged from 0.24 (0.12–0.33) to 3.39 (2.58–4.86) µM, and those of deltamethrin ranged from 0.0041 (0.0031–0.0060) to 2.97 (1.56–4.69) µM. Combinations of phoxim and deltamethrin displayed synergistic effects on zebrafish embryos. The activities of T-SOD, Cu/Zn-SOD, POD, and CarE varied dramatically under most administrations of phoxim, deltamethrin, and phoxim + deltamethrin combinations relative to the baseline value. Nine genes, namely, Mn-sod, Cu/Zn-sod, cas3, dio1, tsh, ERα, vtg1, cyp17, and crh, related to antioxidation, cell apoptosis, immunity, and the endocrine system were altered to a greater degree under the mixture administration compared with the individual administrations.ConclusionsIn summary, our current data offered a detailed insight into the combined toxic impacts of pesticide mixtures at various endpoints and over a wide range of concentrations. The results emphasized the necessity to consider the administration mixtures during the ecological risk assessment of pesticides.

Ecological risk assessment of pesticides in urban streams of the Brazilian Amazon

The use of pesticides in households and peri-urban areas of the Amazon has increased notably during the last years. Yet, the presence of these contaminants in Amazonian freshwater ecosystems remains unexplored. Here, we assessed the exposure to 18 pesticides and 5 transformation products in the Amazon River and in the urban streams of Manaus, Santarém, Macapá, and Belém (Brazil). Pesticide concentrations were analyzed by liquid and gas chromatography methods. Ecological risks were assessed following a two-tiered approach. First, hazard quotients and an overall hazard index were calculated using toxicity data for standard test species of primary producers, invertebrates, and fish. Second, the pesticides showing moderate-to-high ecological risks in the first tier were evaluated using Species Sensitivity Distributions (SSDs). Our study shows that pesticides are widespread in urban and peri-urban areas of the Brazilian Amazon. The frequency of detection was higher in urban streams than in the Amazon River, with some samples taken in Manaus, Santarém, and Belém containing up to 8 compounds. Most pesticides were measured at relatively low concentrations (ng L−1), except for malathion, carbendazim and the bulk concentration of chlorpyrifos, which were monitored at concentrations above 100 ng L−1. Based on the first-tier assessment, we found moderate-to-high risks for freshwater invertebrates for malathion, chlorpyrifos, and chlorpyrifos-methyl, and moderate risks for malathion to fish. The risk assessment performed with SSDs indicated high risks of malathion and chlorpyrifos-methyl in urban areas, with up to 15% and 5% of invertebrate species potentially affected, respectively. The bulk concentrations of chlorpyrifos resulted in high risks in some urban areas (14–22% of species affected) and in areas of the main river (32–44%) impacted by agriculture. We conclude that pesticide residues may contribute to a biodiversity impact in the Amazon and should be further monitored in urban and peri-urban areas, particularly after heavy rainfall events.

Evaluating the Effect of Pesticides on the Larvae of the Solitary Bees.

Current ecological risk assessments of pesticides on pollinators have primarily considered only laboratory conditions. For the larvae of solitary bees, ingestion of provisions contaminated with pesticides may increase the mortality rate of the larvae, decrease the collection rate and the population of adult solitary bees in the next year from a demographic perspective. But there are limited studies on the effects of pesticides on the larvae of solitary bees. Therefore, understanding how pesticides influence the larvae of solitary bees should be considered an integral part of pesticide ecological risk assessment. This study presents a method to expose the larvae of solitary bee, Osmia excavata, to lethal or sublethal doses of pesticide, tracking larval weight gain, developmental duration, eclosion ability, and food consumption efficiency conversion of ingested food. To demonstrate the effectiveness of this method, the larvae of O. excavata were fed with provisions containing acute lethal and sublethal doses of chlorpyrifos. Then, the above indexes of the treated larvae were investigated. This technique helps to predict and mitigate the risk of pesticides to pollinators.

A critical review of exposure and effect modelling approaches for ecological risk assessment of pesticides

A critical review of exposure and effect modelling approaches for ecological risk assessment of pesticides

A critical review of exposure and effect modelling approaches for ecological risk assessment of pesticides

A critical review of exposure and effect modelling approaches for ecological risk assessment of pesticides

Cumulative ecological risk assessment of pesticides using a simulation model (PADDY-Large) and species sensitivity distribution (SSD): Application to a tributary of the Sakura River under rice cultivation

Cumulative ecological risk assessment of pesticides using a simulation model (PADDY-Large) and species sensitivity distribution (SSD): Application to a tributary of the Sakura River under rice cultivation

High sensitivity of invertebrate detritivores from tropical streams to different pesticides

Freshwater organisms are often sensitive to pesticides, but their sensitivity varies across different taxa and with pesticide type and action mode, as shown by multiple acute toxicity tests. Such variability hampers predictions about how freshwater ecosystems may be altered by pesticide toxicity, which is especially critical for understudied areas of the world such as the tropics. Furthermore, there is little information about the sensitivity of some organisms that are key components of stream food webs; this is the case of litter-feeding detritivorous invertebrates, which contribute to the fundamental process of litter decomposition. Here, we examined the sensitivity of three common detritivores [Anchytarsus sp. (Coleoptera: Ptilodactylidae), Hyalella sp. (Amphipoda: Hyalellidae) and Lepidostoma sp. (Trichoptera: Lepidostomatidae)] to three pesticides commonly used (the insecticides bifenthrin and chlorpyrifos and the fungicide chlorothalonil) using acute (48 or 96 h) toxicity tests. Our study demonstrates that common-use pesticides provoke the mortality of half their populations at concentrations of 0.04–2.7 μg L-1. We found that all species were sensitive to the three pesticides, with the highest sensitivity found for chlorpyrifos. Additionally, we used the approach of species sensitivity distributions (SSD) to compare our study species with Daphnia magna and other temperate and tropical invertebrates. We found that the study species were among the most sensitive species to chlorpyrifos and chlorothalonil. Our results suggest that tropical detritivores merit special attention in ecological risk assessment of pesticides and highlight the need for accurate ecotoxicological information from ecologically relevant species in the tropics.

Joint toxicity of imidacloprid and azoxystrobin to Chironomus dilutus at organism, cell, and gene levels

Pesticides occur in the environment as mixtures, yet the joint toxicity of pesticide mixtures remains largely under-explored and is usually overlooked in ecological risk assessment. In the current study, joint toxicity of a neonicotinoid insecticide (imidacloprid, IMI) and a strobilurin fungicide (azoxystrobin, AZO) was investigated with Chironomus dilutus over a wide range of concentrations and at different effect levels (organism, cell, and gene levels). The two pesticides, both individually and in combination, were found to induce oxidative stress and cause lethality in C. dilutus. Median lethal concentrations for IMI and AZO were 3.98 ± 1.17 and 52.9 ± 1.1 μg/L, respectively. Mixtures of the two pesticides presented synergetic effects at environmentally relevant concentrations whilst antagonistic effects at high concentrations, showing concentration-dependent joint toxicity. Investigation on the expressions of 12 genes (cyt b, coi, cox1, cyp4, cyp12m1, cyp9au1, cyp6fv1, cyp315, gst, Zn/Cu-sod, Mn-sod, and cat) revealed that the two pesticides impaired mitochondrial respiration, detoxification, and antioxidant system of C. dilutus, and the joint effects of the two pesticides were likely due to an interplay between their respective influences on these physiological processes. Collectively, the synergistic effects of the two pesticides at environmentally relevant concentrations highlight the importance to incorporate combined toxicity studies into ecological risk assessment of pesticides.

Ecological risk assessment of pesticides in the Mijares River (eastern Spain) impacted by citrus production using wide-scope screening and target quantitative analysis

The widespread use of pesticides, especially in agricultural areas, makes necessary to control their presence in surrounding surface waters. The current study was designed to investigate the occurrence and ecological risks of pesticides and their transformation products in a Mediterranean river basin impacted by citrus agricultural production. Nineteen sites were monitored in three campaigns distributed over three different seasons. After a qualitative screening, 24 compounds was selected for subsequent quantitative analysis. As expected, the lower section of the river was most contaminated, with total concentration >5 µg/L in two sites near to the discharge area of wastewater treatment plants. The highest concentrations were found in September, after agricultural applications and when the river flow is reduced. Ecological risks were calculated using two mixture toxicity approaches (Toxic Unit and multi-substance Potentially Affected Fraction), which revealed high acute and chronic risks of imidacloprid to invertebrates, moderate-to-high risks of diuron, simazine and 2,4-D for primary producers, and moderate-to-high risks of thiabendazole for invertebrates and fish. This study shows that intensive agricultural production and the discharge of wastewater effluents containing pesticide residues from post-harvest citrus processing plants are threatening freshwater biodiversity. Further actions are recommended to control pesticide use and to reduce emissions.

Human health and ecological risk assessment of pesticides from rice production in the Babol Roud River in Northern Iran

Increasing agricultural activities result in increasing use of different pesticides in order to protect the products, but this is happening without paying attention to the consequences of the daily increase of using pesticides. Pesticides could affect human health and the environment at the same time. In this study three pesticides (diazinon, carbaryl and butachlor), which are used in rice production, were measured in the Babol Roud River located in Mazandaran province in Northern Iran. A large portion of the agricultural land use in this region is for rice production. Water samples were collected from 8 sampling points along the river during 4 seasons throughout the year, since planting of rice is conducted twice a year in this region. Mean concentrations for diazinon are 367.7 and 354.5 μgL−1 in October 2018 and June 2019, respectively. Also, concentrations of carbaryl are 197 and 211.1 μgL−1 and butachlor are 299.6 and 413.2 μgL−1 in 2018 and 2019, respectively. Moreover, hazard quotient (HQ) for non-carcinogenic health risk of these pesticides were calculated based on the United States Environmental Protection Agency reference dose (RfD) and the European Union's acceptable daily intake (EU ADI). HQs for adult based on RfD are 4.3, 0.3 and 0.1 and for children are 8.6, 0.08 and 0.03 for diazinon, butachlor and carbaryl, respectively. Also, HQs for adults based on the EU ADI are 15, 0.05 and 0.1 and for children are 30, 0.1 and 0.4 for diazinon, butachlor and carbaryl, respectively. The probabilistic ecological risk assessment indicated that diazinon in the river represents a considerable risk to invertebrate and vertebrate communities, carbaryl to invertebrate communities, and butachlor to primary producer communities. The 5th centile of the species sensitivity distributions for each of these communities of biota are exceeded in more than 75% of samples.

Pesticide exposure affects reproductive capacity of common toads (Bufo bufo) in a viticultural landscape

Amphibian populations are declining worldwide at alarming rates. Among the large variety of contributing stressors, chemical pollutants like pesticides have been identified as a major factor for this decline. Besides direct effects on aquatic and terrestrial amphibian stages, sublethal effects like impairments in reproduction can affect a population. Therefore, we investigated the reproductive capacity of common toads (Bufo bufo) in the pesticide-intensive viticultural landscape of Palatinate in Southwest Germany along a pesticide gradient. In a semi-field study, we captured reproductively active common toad pairs of five breeding ponds with different pesticide contamination level and kept them in a net cage until spawning. Toads from more contaminated ponds showed an increased fecundity (more eggs) but decreased fertilization rates (fewer hatching tadpoles) as well as lower survival rates and reduced size in Gosner stage 25, suggesting that the higher exposed populations suffer from long-term reproductive impairments. In combination with acute toxicity effects, the detected sublethal effects, which are mostly not addressed in the ecological risk assessment of pesticides, pose a serious threat on amphibian populations in agricultural landscapes.

In silico prediction of chemical acute contact toxicity on honey bees via machine learning methods

In recent years, the decline of honey bees and the collapse of bee colonies have caught the attention of ecologists, and the use of pesticides is one of the main reasons for the decline. Therefore, ecological risk assessment of pesticides is essential and necessary. In silico tools, such as QSAR models can play an important role in predicting physicochemical and biological properties of chemicals. In this study, a total of 54 classification models were developed by combination of 6 machine learning methods along with 9 kinds of molecular fingerprints based on the experimental honey bees acute contact toxicity data (LD50) of 676 structurally diverse pesticides. The best model proposed was SVM algorithm combined with CDK extended fingerprint. The analysis of the applicability domain of the model successfully excluded some extreme molecules. Additionally, 9 structural alerts about honey bees acute contact toxicity were identified by information gain and substructure frequency analysis.

Ecological Risk Assessment of Pesticides in Sediments of Pampean Streams, Argentina

Ecological Risk Assessment of Pesticides in Sediments of Pampean Streams, Argentina

Higher mean and fluctuating temperatures jointly determine the impact of the pesticide chlorpyrifos on the growth rate and leaf consumption of a freshwater isopod

There is growing evidence that both increases in mean temperature and the widespread daily temperature fluctuations (DTF) may increase pesticide toxicity. Nevertheless, the likely more stressful, realistic combination of the two warming-related stressors has rarely been considered in ecotoxicology. Moreover, we have little knowledge on whether these stressor combinations could impair ecosystem functioning. We examined the effect of the pesticide chlorpyrifos under an increased mean temperature (+4 °C, from 18 °C to 22 °C) and in the presence of DTF (constant and 8 °C) on two life-history traits (mortality and growth rate) and one ecologically important behavioural trait (feeding rate) in the freshwater isopod Asellus aquaticus. The chlorpyrifos concentration used, 0.2 μg/L, did not cause mortality in any thermal condition, nor did it cause sublethal effects at the mean temperature of 18 °C. A key finding was that growth rate was strongly reduced by the pesticide only under the combination of both a higher mean temperature and DTF, highlighting the importance of testing toxicity under this realistic thermal scenario. The leaf consumption of chlorpyrifos-exposed isopods increased at the higher mean temperature when this was kept constant, however, it lowered again towards control levels when DTF was induced, thereby contributing to the growth reduction at this most stressful condition. These alterations of growth and leaf degradation rates may impact nutrient recycling, a key ecosystem function. Our results highlight the importance of integrating both increases in mean temperature and in DTF to improve current and future ecological risk assessment of pesticides.