Behavior of Glyphosate in Wastewater Treatment Plants.

The herbicide glyphosate is frequently detected in surface waters and its occurrence is linked to agricultural as well as urban uses. Elevated concentrations downstream of wastewater treatment plants (WWTPs) suggest that municipal wastewater is an important source of glyphosate in surface waters. We therefore conducted a study at a typical municipal WWTP in Switzerland to characterize the seasonality of glyphosate occurrence, the removal efficiency, and the processes involved in glyphosate removal. Glyphosate was present in raw (mechanically treated) wastewater during the whole study period (April to November). A lab incubation experiment with activated sludge indicated negligible degradation of glyphosate. Lack of degradation combined with strong adsorption lead to substantial enrichment of the compound in the sludge. Due to this enrichment and the long residence time of activated sludge (several days, compared to hours for wastewater itself), concentrations in treated wastewater show comparatively little variation, whereas concentrations in raw wastewater may fluctuate considerably. Overall removal efficiencies were in the range of 71-96%. This behavior could be described qualitatively using a numerical model that included input of glyphosate via raw wastewater, adsorption to activated sludge, and export via treated wastewater and excess sludge, but excluded degradation processes.

Behavior of the Chiral Herbicide Imazamox in Soils: Enantiomer Composition Differentiates between Biodegradation and Photodegradation.

Imazamox is a chiral herbicide that, in laboratory experiments in the dark, exhibits pronounced enantioselective biodegradation in certain soils. Imazamox also shows rapid photodegradation. However, which processes are predominant in the field is not clear. We conducted a set of soil incubation experiments under natural sunlight (and corresponding dark controls), using enantioselective LC-MS/MS analysis as a probe to distinguish biodegradation and photodegradation. Under dark conditions, imazamox was degraded enantioselectively. In contrast, degradation was nonenantioselective and 2× faster when the soil was exposed to sunlight, suggesting that biodegradation (in the dark) and photodegradation (under sunlight) were the predominant degradation processes. We also investigated the effectiveness of strategies that were proposed to exclude photodegradation in field studies, covering of soil with sand or irrigation after herbicide application. The sand cover did not prevent photodegradation. On the contrary, degradation was 10× faster than in the dark and nonenantioselective. Computer simulations supported the explanation that imazamox was transported upward by capillary flow due to evaporation onto the sand surface, where it was rapidly photodegraded. Irrigation postponed but not completely prevented photodegradation. For mobile substances susceptible to photodegradation, upward transport to the soil surface thus needs to be considered when deriving rates for biodegradation from field studies.

Behavior of the Chiral Herbicide Imazamox in Soils: pH-Dependent, Enantioselective Degradation, Formation and Degradation of Several Chiral Metabolites.

Many pesticides show a pronounced biphasic degradation in soil, typically with a faster initial phase, followed by a slower decline. For chiral compounds, a biphasic decline of the total concentration may result from enantioselective degradation. In this study with the chiral herbicide imazamox, biphasic degradation was observed in most of the 18 soils investigated. In neutral soils, degradation was, in fact, enantioselective with faster degradation of (+)-imazamox. In slightly acidic soils, differences between enantiomers were not pronounced, and in strongly acidic soils, degradation was again enantioselective, but with reversed preference. Additional experiments with pure enantiomers indicated no interconversion. Enantioselective degradation thus contributed to the biphasic decline of the total concentration in certain soils. However, this was not the only factor since degradation of the individual enantiomers was biphasic in itself. In addition to the observed correlation between enantioselectivity and pH, degradation was generally faster in neutral than in acidic soils with half-lives ranging from only 2 to >120 days. Half-lives were also determined for two known metabolites and a further chiral metabolite, the structure of which was characterized by high resolution tandem mass spectrometry. As for the parent compound, half-lives of the metabolites varied considerably in the different soils.

Seasonal Dynamics of Glyphosate and AMPA in Lake Greifensee: Rapid Microbial Degradation in the Epilimnion During Summer.

Occurrence and fate of glyphosate, a widely used herbicide, and its main metabolite AMPA was investigated in Lake Greifensee, Switzerland. Monthly vertical concentration profiles in the lake showed an increase of glyphosate concentrations in the epilimnion from 15 ng/L in March to 145 ng/L in July, followed by a sharp decline to <5 ng/L in August. A similar pattern was observed for AMPA. Concentrations of glyphosate and AMPA in the two main tributaries generally were much higher than in the lake. Simulations using a numerical lake model indicated that a substantial amount of glyphosate and AMPA dissipated in the epilimnion, mainly in July and August, with half-lives of only ≈2-4 days which is ≫100 times faster than in the preceding months. Fast dissipation coincided with high water temperatures and phytoplankton densities, and low phosphate concentrations. This indicates that glyphosate might have been used as an alternative phosphorus source by bacterio- and phytoplankton. Metagenomic analysis of lake water revealed the presence of organisms known to be capable of degrading glyphosate and AMPA.

Online solid phase extraction LC-MS/MS method for the analysis of succinate dehydrogenase inhibitor fungicides and its applicability to surface water samples.

A sensitive and selective analytical method, based on online solid phase extraction coupled to LC-MS/MS, was developed and validated to determine traces of several recently introduced fungicides in surface water and wastewater. The list of target analytes included eight succinate dehydrogenase inhibitors (bixafen, boscalid, fluopyram, flutolanil, fluxapyroxad, isopyrazam, penflufen, and penthiopyrad), and two other fungicides with different modes of action, fenpyrazamine and fluopicolide. Detection and quantification limits in various matrices were in the range of 0.1 to 2 and 0.5 to 10 ng/L, respectively. Moderate signal suppression was observed in surface water (≤15%) and wastewater (≤25%) and was well compensated by the selected internal standard. The intra- and inter-day precisions were generally <10 and <20%, respectively. The applicability of the method was demonstrated in a study on the occurrence of fungicides in the river Glatt, Switzerland, that drains a catchment area of 419 km(2) with a substantial proportion of agricultural land. Of the studied compounds, only boscalid and fluopicolide were detected in flow-proportional weekly composite samples, generally at low concentrations up to 15 and 5 ng/L, respectively. While fluopicolide was detected in only 30% of the samples above the LOD of 0.5 ng/L, boscalid was detected in all samples analyzed between March and October 2012.

Safety and efficacy of a feed additive consisting of monensin sodium (Coxidin®) for chickens for fattening, chickens reared for laying, turkeys for fattening and turkeys reared for breeding (Huvepharma N.V.).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of monensin sodium (Coxidin®) as a coccidiostat for chickens for fattening, chickens reared for laying, turkeys for fattening and turkeys reared for breeding. The additive currently on the market complies with the existing conditions of authorisation. The FEEDAP Panel concluded that Coxidin® remains safe for turkeys for fattening (up to 16 weeks) and extends this conclusion to turkeys reared for breeding (up to 16 weeks). The Panel was not in the position to confirm that the current maximum authorised level of 125 mg monensin sodium/kg complete feed remains safe for chickens for fattening and chickens reared for laying. The use of monensin sodium from Coxidin® at the corresponding maximum authorised/proposed use levels in the target species is safe for the consumer. The existing maximum residue levels (MRLs) for poultry tissues ensure consumer safety. No withdrawal time is necessary. Both formulations of Coxidin® pose a risk by inhalation. The formulation with wheat bran as a carrier was neither irritant to the skin nor a skin sensitiser but it was irritant to the eyes. In the absence of data, no conclusions could be made on the potential of the formulation containing calcium carbonate to be irritant to skin and eyes and to be a skin sensitiser. The use of monensin sodium from Coxidin® in complete feed for the target species poses no risk for the terrestrial compartments and for sediment. No risk for groundwater is expected. For chickens for fattening the risk for aquatic compartment cannot be excluded, but no risks are expected for the other animal categories. There is no risk of secondary poisoning. Coxidin® is efficacious in controlling coccidiosis at a level of 100 mg/kg complete feed for chickens for fattening and at 60 mg/kg complete feed for turkeys for fattening. These conclusions are extended to chickens reared for laying and turkeys reared for breeding. The Panel noted that there are signs of development of resistance of Eimeria spp. to monensin sodium.

Safety and efficacy of a feed additive consisting of salinomycin sodium (Sacox®) for rabbits for fattening (Huvepharma N.V.).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of the coccidiostat salinomycin sodium (Sacox®) for rabbits for fattening. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the use of salinomycin sodium (SAL-Na) from Sacox® does not raise safety concerns for the target species, consumers, users and the environment with regard to the production strain. In the absence of adequate tolerance studies, the FEEDAP Panel could not conclude on the safety of SAL-Na from Sacox® for rabbits for fattening. The FEEDAP Panel concluded that the additive is safe for the consumer when it is used at the proposed maximum level of 25 mg SAL-Na/kg complete feed for rabbits and a withdrawal period of 1 day is respected. The following maximum residue limits (MRL) are proposed for the marker residue compound salinomycin (SAL): 0.2 and 0.03 mg SAL/kg for liver and kidney, respectively. The additive is not irritant to skin and eyes but should be considered a potential dermal and respiratory sensitiser. A risk for inhalation toxicity could not be excluded. The use of the SAL-Na from Sacox® in feed for rabbits for fattening up to the highest proposed level will not pose a risk for the terrestrial and aquatic compartment and ground water. The risk of secondary poisoning can be excluded for worm-eating birds and mammals, while it cannot be excluded for fish-eating birds and mammals. The FEEDAP Panel concludes that SAL-Na from Sacox® at the minimum concentration of 20 mg SAL-Na/kg complete feed has the potential to control coccidiosis in rabbits for fattening. Development of resistance to SAL-Na of field Eimeria spp. strains isolated from rabbits for fattening should be monitored.

Enantioselective dehydrochlorination of δ-Hexachlorocyclohexane and δ-Pentachlorocyclohexene by LinA1 and LinA2 from Sphingobium indicum B90A.

δ-Hexachlorocyclohexane (δ-HCH), one of the prevalent isomers of technical HCH, was enantioselectively dehydrochlorinated by the dehydrochlorinases LinA1 and LinA2 from Sphingobium indicum B90A to the very same δ-pentachlorocyclohexene enantiomer. Racemic δ-pentachlorocyclohexene, however, was transformed with opposite enantioselectivities by the two enzymes. A transformation pathway based on an anti-1,2-elimination, followed by a syn-1,4-elimination and a subsequent syn-1,2-elimination is postulated.

The chiral herbicide beflubutamid (II): Enantioselective degradation and enantiomerization in soil, and formation/degradation of chiral metabolites.

Beflubutamid is a chiral soil herbicide currently marketed as racemate against dicotyledonous weeds in cereals. Biotests have shown that (-)-beflubutamid is at least 1000× more active than (+)-beflubutamid. Potential substitution of the racemate by (-)-beflubutamid should therefore be further considered. Here, we investigated the degradation behavior in soils and formation and degradation of two chiral metabolites. Laboratory incubation experiments were performed with an alkaline and an acidic soil. The compounds were analyzed by enantioselective GC-MS. Degradation rate constants were determined by kinetic modeling. In the alkaline soil, degradation of beflubutamid was slightly enantioselective, with slower degradation of the herbicidally active (-)-enantiomer. In the acidic soil, however, both enantiomers were degraded at similar rates. In contrast, degradation of a phenoxybutanamide metabolite was highly enantioselective. Chiral stability of beflubutamid and its metabolites was studied in separate incubations with the pure enantiomers in the same soils. In these experiments, (-)-beflubutamid was not converted to the nonactive (+)-enantiomer and vice versa. Significant enantiomerization was, however, observed for the major metabolite, a phenoxybutanoic acid. With regard to biological activity and behavior in soils, enantiopure (-)-beflubutamid definitively has the potential to substitute for the racemic herbicide.

The chiral herbicide beflubutamid (I): Isolation of pure enantiomers by HPLC, herbicidal activity of enantiomers, and analysis by enantioselective GC-MS.

For many chiral pesticides, little information is available on the properties and fate of individual stereoisomers. A basic data set would, first of all, include stereoisomer-specific analytical methods and data on the biological activity of stereoisomers. The herbicide beflubutamid, which acts as an inhibitor of carotenoid biosynthesis, is currently marketed as racemate against dicotyledonous weeds in cereals. Here, we present analytical methods for enantiomer separation of beflubutamid and two metabolites based on chiral HPLC. These methods were used to assign the optical rotation and to prepare milligram quantities of the pure enantiomers for further characterization with respect to herbicidal activity. In addition, sensitive analytical methods were developed for enantiomer separation and quantification of beflubutamid and its metabolites at trace level, using chiral GC-MS. In miniaturized biotests with garden cress, (-)-beflubutamid showed at least 1000× higher herbicidal activity (EC50, 0.50 µM) than (+)-beflubutamid, as determined by analysis of chlorophyll a in 5-day-old leaves. The agricultural use of enantiopure (-)-beflubutamid rather than the racemic compound may therefore be advantageous from an environmental perspective. In further biotests, the (+)-enantiomer of the phenoxybutanoic acid metabolite showed effects on root growth, possibly via an auxin-type mode of action, but at 100× higher concentrations than the structurally related herbicide (+)-mecoprop.

Residues of pesticide co-formulants in lettuce and parsley: Identification of decline processes using field trials in different cropping systems.

BACKGROUND: Although co-formulants constitute a substantial portion of the total plant protection product (PPP) mass applied to crops, data on residue formation and the behaviour of these substances on plants are scarce. In an earlier study we demonstrated that co-formulants commonly used in PPPs can form considerable residues, i.e., in the low to medium mg/kg range, but normally decline rapidly within few days. In the field trial reported here, we aimed to identify the major decline processes of co-formulants. Residues of co-formulants were therefore monitored in parsley and lettuce grown in an open field as well as under foil tunnels equipped with either an overhead or a drip irrigation system. RESULTS: Dissipation of three anionic surfactants was markedly faster when crops (parsley and lettuce) were exposed to natural rainfall or irrigation from above compared to drip irrigation. In contrast, the decline of three volatile organic solvents was not affected by rain or irrigation, but was dependent on the crop, with much shorter half-lives in lettuce than in parsley. Furthermore, dilution through plant growth contributed significantly to the reduction of residues over time. CONCLUSION: In this work we substantiate earlier findings on the magnitude and dissipation of residues of anionic surfactants and solvents representing the most important co-formulant classes. The chosen experimental setup allowed differentiation between decline processes and we confirm that foliar wash-off is a major dissipation process for anionic surfactants. For volatile organic solvents, dissipation appears to depend on the properties not only of the substance but also of the plant (surface). © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Safety for the environment of a feed additive consisting of diclazuril (Coxiril®) for chickens reared for laying and pheasants (Huvepharma NV).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety for the environment of diclazuril (Coxiril®) as a coccidiostat feed additive for chickens reared for laying and pheasants. In its previous assessments, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) could not reach a final conclusion on the risk resulting from the use of diclazuril in acid soil from Coxiril®. On the basis of the new data provided, the FEEDAP Panel updates the previous conclusions as follows: no risk is expected for the terrestrial compartment and for sediment when diclazuril is used in chickens reared for laying and to pheasants at the proposed condition of use (in both acidic and non-acidic soils). No concern for groundwater is expected for both acidic and non-acidic soils. Due to the lack of data, no conclusions can be drawn for the aquatic compartment. Diclazuril does not have the potential for bioaccumulation; therefore, a risk of secondary poisoning is unlikely.

Safety of a feed additive consisting of sodium saccharin for suckling and weaned piglets, fattening pigs, calves for rearing and for fattening (FEFANA asbl).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety of sodium saccharin as a sensory feed additive (flavouring compound) for suckling and weaned piglets, fattening pigs, calves for rearing and for fattening. In a previous assessment, the Panel on Additives and Products or substances used in Animal Feed (FEEDAP Panel) could not conclude on the safety of the additive for the environment because concentrations of the additive or its degradation product 4-hydroxysaccharin in groundwater above 0.1 µg/L were likely to occur. In addition, regarding user safety, sodium saccharin was considered to be potentially harmful by inhalation or by contact to skin and eyes. In the current opinion, the applicant restricted the use to suckling and weaned piglets and up to a use level of 5 mg/kg complete feed. In relation to the user safety, the additive was neither a skin or eye irritant, nor a dermal sensitiser. In the absence of data, the FEEDAP Panel could not conclude on the potential of the additive to be toxic by inhalation. Regarding the safety of the additive for the environment, the new conditions of use describe a maximum use level of 5 mg sodium saccharin/kg feed. The applicant indicated that a restriction to a lower use level due to environmental safety would be accepted and submitted an environment risk assessment based on a use level of 1.13 mg sodium saccharin/kg feed. This use level cannot be considered safe. The estimated use level that would result in a concentration in groundwater below 0.1 µg/L is of 0.022 mg sodium saccharin/kg feed. The available data do not allow to conclude on the potential effect of the degradation product 4-hydroxysaccharin in ground water.

Safety and efficacy of a feed additive consisting of halofuginone hydrobromide (STENOROL®) for chickens for fattening and turkeys for fattening/reared for breeding (Huvepharma N.V.).

Following a request from the European Commission, EFSA was asked to deliver a new scientific opinion on the coccidiostat halofuginone hydrobromide (STENOROL®) when used as a feed additive for chickens for fattening and turkeys for fattening/reared for breeding. The Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concludes that the safety for turkeys for fattening established in its previous opinion can be extended to turkeys for breeding up to 12 weeks of age. Based on the new data provided on the safety for consumer, environment and efficacy, the Panel updates its previous conclusions as follows: halofuginone hydrobromide is not genotoxic. Applying an uncertainty factor of 100 to the lowest no observed adverse effect level (NOAEL) of 0.03 mg/kg body weight (bw) per day, an acceptable daily intake (ADI) of 0.3 µg halofuginone/kg bw is established. The chronic exposure of consumers to residues of halofuginone would amount to 6-19% of the ADI after 3 days of withdrawal. Therefore, the Panel considers that the additive is safe for the consumer of tissues obtained from chickens for fattening and turkeys for fattening fed the additive at a maximum level of 3 mg/kg complete feed at a 3-day withdrawal time. For control purposes, the Panel recommends the setting of the following maximum residue limits (MRLs): liver, 50 µg/kg; kidney, 40 µg/kg; muscle, 3 µg/kg; skin/fat, 10 µg/kg wet tissue. Based on an updated environmental risk assessment, no concern for groundwater is expected. Halofuginone is unlikely to bioaccumulate and the risk of secondary poisoning is not likely to occur. No safety concerns are expected for terrestrial and aquatic environments. The additive has the potential to control coccidiosis in chickens for fattening and turkeys for fattening/reared for breeding up to 12 weeks of age at a minimum level of 2 mg/kg complete feed.

Safety and efficacy of a feed additive consisting of copper(II)-betaine complex for all animal species (Biochem Zusatzstoffe Handels- und Produktionsges. mbH).

Following a request from the European Commission, the EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP Panel) was asked to deliver a scientific opinion on the safety and efficacy of a copper(II)-betaine complex as nutritional feed additive for all animal species. Based on the results of a tolerance study carried out in chicken, the FEEDAP Panel concluded that the additive is safe for chickens for fattening when used up to the current maximum authorised levels of copper in feed; this conclusion was extrapolated to all animal species and categories at the respective maximum copper levels in complete feed authorised in the European Union. The FEEDAP Panel concluded that the use of the copper(II)-betaine complex in animal nutrition at the maximum copper levels authorised for the animal species poses no concern to the safety of consumers. Regarding the safety for the environment, the use of the additive in feed for terrestrial animals and land-based aquaculture is considered safe under proposed conditions of use. The data available do not allow the conclusion to be made on the safety of the additive for marine sediment when it is used in sea cages. The additive is not a skin irritant, but it is an irritant to the eyes. Due to the traces of nickel, the additive is considered to be a respiratory and skin sensitiser. The Panel could not conclude on the efficacy of the product.

Safety and efficacy of a feed additive consisting of a zinc(II)-betaine complex for all animal species (Biochem Zusatzstoffe Handels- und Produktionsges. mbH).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of a zinc(II)-betaine complex as nutritional additive for all animal species. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the additive is safe for chickens for fattening. This conclusion could be extrapolated to all animal species and categories provided that the maximum authorised levels in the EU for total zinc in feed are not exceeded. The FEEDAP Panel concluded that the use of the zinc(II)-betaine complex in animal nutrition is of no concern for consumer safety provided that the maximum authorised total zinc levels in feed are respected. The additive is considered to be a skin and respiratory sensitiser due to the presence of nickel; it is irritant to the eyes, but not to the skin. The use of the additive in animal nutrition for terrestrial animals and land-based aquaculture at the proposed use levels is considered safe for terrestrial and aquatic ecosystems. The available data do not allow the conclusion to be made on the safety of the additive for the marine sediment when it is used in sea cages. Based on the deposition of zinc in edible tissues/organs in chickens for fattening, the FEEDAP Panel concluded that the additive is a source of bioavailable zinc, comparable to the standard inorganic zinc source, and therefore, the additive is efficacious in meeting the birds zinc requirements. This conclusion can be extrapolated to all animal species and categories.

Enzymatic conversion of ε-hexachlorocyclohexane and a heptachlorocyclohexane isomer, two neglected components of technical hexachlorocyclohexane.

α-, ß, γ-, and δ-Hexachlorocyclohexane (HCH), the four major isomers of technical HCH, are susceptible to biotic transformations, whereby only α- and γ-HCH undergo complete mineralization. Nevertheless, LinA and LinB catalyzing HCl elimination and hydrolytic dehalogenations, respectively, as initial steps in the mineralization also convert ß- and δ-HCH to a variety of mainly hydroxylated metabolites. In this study, we describe the isolation of two minor components of technical HCH, ε-HCH, and heptachlorocyclohexane (HeCH), and we present data on enzymatic transformations of both compounds by two dehydrochlorinases (LinA1 and LinA2) and a haloalkane dehalogenase (LinB) from Sphingobium indicum B90A. In contrast to reactions with α-, γ-, and δ-HCH, both LinA enzymes converted ε-HCH to a mixture of 1,2,4-, 1,2,3-, and 1,3,5-trichlorobenzenes without the accumulation of pentachlorocyclohexene as intermediate. Furthermore, both LinA enzymes were able to convert HeCH to a mixture of 1,2,3,4- and 1,2,3,5-tetrachlorobenzene. LinB hydroxylated ε-HCH to pentachlorocyclohexanol and tetrachlorocyclohexane-1,4-diol, whereas hexachlorocyclohexanol was the sole product when HeCH was incubated with LinB. The data clearly indicate that various metabolites are formed from minor components of technical HCH mixtures. Such metabolites will contribute to the overall toxic potential of HCH contaminations and may constitute serious, yet unknown environmental risks and must not be neglected in proper risk assessments.

Saccharin and other artificial sweeteners in soils: estimated inputs from agriculture and households, degradation, and leaching to groundwater.

Artificial sweeteners are consumed in substantial quantities as sugar substitutes and were previously shown to be ubiquitously present in the aquatic environment. The sweetener saccharin is also registered as additive in piglet feed. Saccharin fed to piglets was largely excreted and, consequently, found in liquid manure at concentrations up to 12 mg/L, where it was stable during 2 months of storage. Saccharin may thus end up in soils in considerable quantities with manure. Furthermore, other studies showed that saccharin is a soil metabolite of certain sulfonylurea herbicides. Sweeteners may also get into soils via irrigation with wastewater-polluted surface water, fertilization with sewage sludge (1-43 µg/L), or through leaky sewers. In soil incubation experiments, cyclamate, saccharin, acesulfame, and sucralose were degraded with half-lives of 0.4-6 d, 3-12 d, 3-49 d, and 8-124 d, respectively. The relative importance of entry pathways to soils was compared and degradation and leaching to groundwater were evaluated with computer simulations. The data suggest that detection of saccharin in groundwater (observed concentrations, up to 0.26 µg/L) is most likely due to application of manure. However, elevated concentrations of acesulfame in groundwater (up to 5 µg/L) may result primarily from infiltration of wastewater-polluted surface water through stream beds.

Magnitude and decline of pesticide co-formulant residues in vegetables and fruits: results from field trials compared to estimated values.

BACKGROUND: The application of plant protection products (PPPs) leads to the formation of residues in treated crops. Even though PPPs contain considerable amounts of co-formulants, regulation and monitoring of residues normally focus on the active substances (a.s.) only. For our study we selected four commonly used co-formulants (three anionic surfactants and one organic solvent) and investigated the formation and decline of residues in vegetables and apples under field conditions. The aims were to characterize the behavior of co-formulant residues on crops and to provide a basis for future investigations on consumer exposure. RESULTS: The development of robust and sensitive analytical methods allowed the quantification of residues in the low µg/kg-level. After treatment with PPPs, co-formulants were detected up to approximately 10 mg kg-1 in vegetables. In general, these residues declined fast with half-lives of a few days. Wash-off and volatilization were identified as important removal processes for anionic surfactants and the organic solvent, respectively. However, in specific crops (parsley and celery), organic solvent residues were still considerable (≈2 mg kg-1 ) 2 weeks after treatment. We further demonstrate that it is feasible to estimate co-formulant residues using publicly available data on pesticide a.s. CONCLUSION: To date no information on co-formulant residues in food is available. The findings from our field trials, as well as the presented approach for the prediction of residues, provide key elements for future consideration of consumer exposure to PPP co-formulants. © 2020 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Hydrophilic anthropogenic markers for quantification of wastewater contamination in ground- and surface waters.

Hydrophilic, persistent markers are useful to detect, locate, and quantify contamination of natural waters with domestic wastewater. The present study focused on occurrence and fate of seven marker candidates including carbamazepine (CBZ), 10,11-dihydro-10,11-dihydroxycarbamazepine (DiOH-CBZ), primidone (PMD), crotamiton (CTMT), N-acetyl-4-aminoantipyrine (AAA), N-formyl-4-aminoantipyrine (FAA), and benzotriazole (BTri) in wastewater treatment plants (WWTPs), lakes, and groundwater. In WWTPs, concentrations from 0.14 microg/L to several micrograms per liter were observed for all substances, except CTMT, which was detected at lower concentrations. Loads determined in untreated and treated wastewater indicated that removal of the potential markers in WWTPs is negligible; only BTri was partly eliminated (average 33%). In lakes, five compounds, CBZ, DiOH-CBZ, FAA, AAA, and BTri, were consistently detected in concentrations of 2 to 70 ng/L, 3 to 150 ng/L, less than the limit of quantification to 30 ng/L, 2 to 80 ng/L, and 11 to 920 ng/L, respectively. Mean per capita loads in the outflows of the lakes suggested possible dissipation in surface waters, especially of AAA and FAA. Nevertheless, concentrations of CBZ, DiOH-CBZ, and BTri correlated with the actual anthropogenic burden of the lakes by domestic wastewater, indicating that these compounds are suitable for quantification of wastewater contamination in lakes. Marker candidates were also detected in a number of groundwater samples. Carbamazepine concentrations up to 42 ng/L were observed in aquifers with significant infiltration of river water, receiving considerable wastewater discharges from WWTPs. Concentration ratios between compounds indicated some elimination of BTri and DiOH-CBZ during subsurface passage or in groundwater, while CBZ and PMD appeared to be more stable and thus are promising wastewater markers for groundwater. The wastewater burden in groundwater, estimated with the markers CBZ and PMD, reached up to 6%.