Organophosphate pesticides (OPPs) are one type of the most massively used pesticides and ubiquitously detected in aquatic environments, which may pose potential risks to the aquatic organisms and human health. In the present study, the spatiotemporal distribution and potential risks of OPPs were investigated in overlying water and surficial sediments from urban waterways of Guangzhou. For all studied sites, in general, four target OPPs (i.e., malathion, chlorpyrifos, terbufos, and diazinon) were present in the overlying water, with malathion and chlorpyrifos as major components. Higher concentrations of the four OPPs were found for the water and sediments collected in the dry season compared to the wet season, possibly because of the dilution effect of heavy rains. The results of Pearson’s analyses and principal coordinate analyses (PCoA) suggested similar sources for target OPPs in the water and sediments across the Guangzhou urban waterways. Potential ecological risks of the OPPs to three representative taxons (algae, aquatic invertebrates, and fish) were evaluated via toxic units (TUs) and risk quotients (RQs), while risk assessment on human health was performed using hazard index (HI). Although TU results showed no acute risks to the aquatic organisms in the overlying water and surface sediments, RQ results of the mixture showed high risks to the aquatic invertebrate and fish in all water samples. Individual HI values and cumulative HI values were on the order of 10⁻⁶–10⁻³ for children and adults, suggesting no potential risks to either children or adults through drinking and bathing.

One hundred two semivolatile organic compounds (SVOCs), including 20 organochlorine pesticides (OCPs) and 12 organophosphorus pesticides (OPPs), were determined in the main rivers of Shenzhen, China. As a result, p,p’-dichlorodiphenyldichloroethane (DDD), aldrin, and benzoepin sulfate were the main OCPs detected in surface water, and p,p’-DDD, heptachlor, and endrin aldehyde were the main compounds in sediment. In addition, diazinon was the most frequent OPP detected in both water and sediment. At most sites, SVOCs were at similar concentration levels in 2017 and 2018. Compared with other areas, diazinon and malathion had comparative high concentrations in Maozhou River in this study. Analyzed from the SVOCs concentrations in water and sediment, p,p’-DDD was from the quick degradation of p,p’-dichlorodiphenyltrichloroethane (DDT), and no recent DDT was input around the investigated area. Besides, the interrelationships among these pollutants were calculated, revealing that OPPs were mainly from the chronically cumulative content, rather than the directly transferring from surface water to sediment. According to the risk assessment, the occurrence of p,p’-DDD and p,p’-DDT affected the aquatic community. All in all, further investigations on the occurrence and source of these pollutants are still needed to avoid the potential risk for human beings living around the contaminated environment.

The current study aimed to evaluate the removal of a pesticide mixture composed of the insecticides chlorpyrifos (CP) and diazinon (DZ) from liquid medium, soil and a biobed biomixture by a Streptomyces mixed culture. Liquid medium contaminated with 100 mg L⁻¹ CP plus DZ was inoculated with the Streptomyces mixed culture. Results indicated that microorganisms increased their biomass and that the inoculum was viable. The inoculum was able to remove the pesticide mixture with a removal rate of 0.036 and 0.015 h⁻¹ and a half-life of 19 and 46 h⁻¹ for CP and DZ, respectively. The sterilized soil and biobed biomixture inoculated with the mixed culture showed that Streptomyces was able to colonize the substrates, exhibiting an increase in population determined by quantitative polymerase chain reaction (q-PCR), enzymatic activity dehydrogenase (DHA) and acid phosphatase (APP). In both the soil and biomixture, limited CP removal was observed (6–14%), while DZ exhibited a removal rate of 0.024 and 0.060 day⁻¹ and a half-life of 29 and 11 days, respectively. Removal of the organophosphorus pesticide (OP) mixture composed of CP and DZ from different environmental matrices by Streptomyces spp. is reported here for the first time. The decontamination strategy using a Streptomyces mixed culture could represent a promising alternative to eliminate CP and DZ residues from liquids as well as to eliminate DZ from soil and biobed biomixtures.

This study assessed effects of a mixture of two pesticides, diazinon and permethrin, on 48-h sediment toxicity to Hyalella azteca in a constructed wetland mesocosm containing non-vegetated and vegetated sections. Sediment samples were collected at inflow, middle, and back points within each section 5, 24, 72 h, 7, 14, and 21 days post-amendment. Pesticides were detected in sediments throughout non-vegetated and vegetated wetland sections. H. azteca 48-h survival varied across sampling period, wetland location, and vegetation type with lowest survival occurring within the first 72 h of the inflow and middle locations of the non-vegetated section. Sediment toxicity was ameliorated by 14 and 7 days within the non-vegetated and vegetated sections, respectively. Relationships between pesticide concentrations and animal survival indicated toxicity was from both diazinon and cis-permethrin in the non-vegetated section and primarily cis-permethrin in the vegetated section. Results show that vegetation ameliorated pesticide mixture 48-h sediment toxicity to H. azteca earlier and to a greater extent than non-vegetated constructed wetlands. A 21-day retention time is necessary to improve 48-h H. azteca sediment survival to ≥90% in wetlands of this size.

The effects of diazinon (DZN), an organophosphate pesticide, on lipid profiles have been extensively reported. However, controversy on this issue persists. Here, we performed a systematic and meta-analysis study to investigate the association between DZN exposure and dyslipidemia in rodents and fish species. This systematic review was prepared according to the PRISMA guidelines. Main databases, including Google Scholar, Scopus, PubMed, Ovid MEDLINE, and Web of Science, were systematically searched through March 4, 2020. The risk of bias was evaluated with the SYRCLE’s RoB tool. Once all articles were assessed for scientific quality, a random-effects model was applied to perform a pooled analysis. I² and Q test were used to assess the heterogeneity between articles, and Forest plots, indicating point and pooled estimates, were drawn. Twenty-eight articles were included; between them, 13 publications were selected for meta-analysis. Random-effects meta-analysis showed low heterogeneity between the articles. A pooled analysis indicated that DZN significantly increased total cholesterol levels (95% CI: 0.86–3.79; Z = 3.10; p = 0.002), triglyceride (95% CI: 0.38–3.22; Z = 2.48; p = 0.09), low-density lipoprotein cholesterol (95% CI: 0.25–2.85; Z = 2.34; p = 0.7) in the DZN vs. control groups. In addition, DZN significantly decreased high-density lipoprotein cholesterol (95% CI: − 2.92, − 0.42; Z = 2.62; p = 0.07) in the DZN vs. control groups. No publication bias was observed. Our findings suggest that DZN induces dyslipidemia in rodents and fish species in a dose-dependent manner.

The bacterial strain Sphingobium sp. YW16, which is capable of degrading monocrotophos, was isolated from paddy soil in China. Strain YW16 could hydrolyze monocrotophos to dimethylphosphate and N-methylacetoacetamide and utilize dimethylphosphate as the sole carbon source but could not utilize N-methylacetoacetamide. Strain YW16 also had the ability to hydrolyze other organophosphate pesticides. A fragment (7067 bp) that included the organophosphorus hydrolase gene, opdA, was acquired from strain YW16 using the shotgun technique combined with SEFA-PCR. Its sequence illustrated that opdA was included in TnopdA, which consisted of a transpose gene, a putative integrase gene, a putative ATP-binding protein gene, and opdA. Additionally, a conjugal transfer protein gene, traI, was located downstream of TnopdA. The juxtaposition of TnopdA with TraI suggests that opdA may be transferred from strain YW16 to other bacteria through conjugation. OpdA was able to hydrolyze a wide range of organophosphate pesticides, with the hydrolysis efficiency decreasing as follows: methyl parathion > fenitrothion > phoxim > dichlorvos > ethyl parathion > trichlorfon > triazophos > chlorpyrifos > monocrotophos > diazinon. This work provides the first report of opdA in the genus Sphingobium.

The area around Lake Ziway in Ethiopia is going through a major agricultural transformation with both small-scale farmers and large horticultural companies using pesticides and fertilisers at an increased rate. To be able to understand how this influences the water quality of Lake Ziway, water quality data was gathered to study the dynamics of pesticide concentrations and physicochemical parameters for the years from 2009 to 2015. Results indicate that for some physicochemical parameters, including pH, potassium and iron, over 50 % of the values were above the maximum permissible limit of the Ethiopian standard for drinking water. The fungicide spiroxamine poses a high chronic risk when the water is used for drinking water, while the estimated intake of diazinon was approximately 50 % of the acceptable daily intake. Higher-tier risk assessment indicated that the fungicide spiroxamine poses a high acute risk to aquatic organisms, while possible acute risks were indicated for the insecticides deltamethrin and endosulfan. Longer-term monitoring needs to be established to show the water quality changes across time and space, and the current study can be used as a baseline measurement for further research in the area as well as an example for other surface water systems in Ethiopia and Africa.

The present study evaluated the effect of two oral doses of the pesticide diazinon (25 and 125 mg/kg bw) on four biochemical parameters (malondialdehyde and glutathione levels, and catalase and glutathione S-transferase enzymatic activities) in the kidney, lungs, and liver of rabbit after 10 days of exposure. Malondialdehyde levels were significantly greater in exposed animals compared to controls, especially in the animals exposed to the higher dose of the pesticide. This result was reflected in the glutathione levels, which were significantly lower at that same higher dose. Catalase activity was also inhibited by the higher dose of the pesticide in all three organs analysed, whereas inhibition of glutathione S-transferase activity was only significant for the kidney and lungs. There were some slight differences between the sexes: taking the results for all three organs, the higher dose of diazinon resulted in a clearly significant inhibitory effect on the catalase activity and glutathione levels in males, and a significant enhancing effect on the malondialdehyde levels in females. These results help to confirm the interest of considering such endogenous factors in future ecotoxicological studies, and that the four biomarkers considered are suitable for reflecting the toxic effects of diazinon on rabbits, especially the effects related to oxidative stress. Graphical abstract

Biofilters have been shown to be efficient for removing pollutants from different water effluents, but little information is available about their capacity to remove highly polar pesticides from agricultural run-off waters. In this study, we assess the capacity of three different biofilter-supporting materials (sand, peat soil, and pine bark) to remove five phenoxyacid herbicides (mecoprop, dicamba, MCPA, dichlorprop and 2,4-D) and five non-ionic pesticides (atrazine, simazine, fenitrotion, diazinon, and alachlor) from real agricultural run-off waters. The experimental design included three columns 120 cm in length and 15 cm in diameter, each filled with 100 cm of one of the selected supporting materials. After 30 days of acclimation, the columns were fed with agricultural run-off water spiked at 10 μg L⁻¹ with each of the studied pesticides for 20 days at a hydraulic loading rate (HLR) of 0.32 m day⁻¹. The results show that the sand filter was the best supporting material for removing phenoxyacid herbicides (77% on average), whereas peat soil and pine bark were best for removing non-ionic pesticides (72% on average). The attenuation of mecoprop and dichlorprop correlated negatively with the enantiomeric fraction. Therefore, this study shows that the use of waste-to-product materials in biofilter systems is a good solution for removing pollutants from agricultural run-off waters.

Costa Rica is a tropical country with one of the highest biodiversity on Earth. It also has an intensive agriculture, and pesticide runoff from banana and pineapple plantations may cause a high toxicity risk to non-target species in rivers downstream the plantations. We performed a first tier risk assessment of the maximum measured concentrations of 32 pesticides detected over 4 years in the River Madre de Dios (RMD) and its coastal lagoon on the Caribbean coast of Costa Rica. Species sensitivity distributions (SSDs) were plotted in order to derive HC₅ values for each pesticide, i.e., hazard concentrations for 5 % of the species, often used as environmental criteria values in other countries. We also carried out toxicity tests for selected pesticides with native Costa Rican species in order to calculate risk coefficients according to national guidelines in Costa Rica. The concentrations of herbicides diuron and ametryn and insecticides carbofuran, diazinon, and ethoprophos exceeded either the HC₅ value or the lower limit of its 90 % confidence interval suggesting toxic risks above accepted levels. Risk coefficients of diuron and carbofuran derived using local guidelines indicate toxicity risks as well. The assessed fungicides did not present acute toxic risks according to our analysis. Overall, these results show a possible toxicity of detected pesticides to aquatic organisms and provide a comparison of Costa Rican national guidelines with more refined methods for risk assessment based on SSDs. Further higher tier risk assessments of pesticides in this watershed are also necessary in order to consider pesticide water concentrations over time, toxicity from pesticide mixtures, and eventual effects on ecosystem functions.