Uptake Of Pesticides Research Articles

Use of semipermeable membrane devices for studying effects of organic pollutants: Comparison of pesticide uptake by semipermeable membrane devices and mussels

Uptake of four pesticides—the organochlorines chlordane and endosulfan and the synthetic pyrethroids fenvalerate and allethrin—by triolein-containing semipermeable membrane devices (SPMD) and by the lake mussel Anodonta piscinalis was studied in a laboratory continuous-flow system. Uptake of the analytes by the SPMDs and mussels was linear during the exposure period of 20 d. These kinetic data were used to calculate the first-order uptake rate constants. On a SPMD-whole body basis, the uptake rates were 3.5 to 5.5 times higher in the membrane devices than in the organisms. The synthetic pyrethroids were sampled at lower rates than the organochlorines, and this difference may be attributed to the larger molecular dimensions of the pyrethroids rather than analyte molecular weight and lipophilicity, which were similar for all test compounds. Because of the disparate sampling rates, concentration factors of analytes differed between SPMDs and mussels. However, the percent composition (ratios) of analytes in SPMDs and in mussels was similar, which indicates that SPMDs may serve as good surrogates for aquatic organisms with respect to the discriminatory uptake of hydrophobic chemicals. Semipermeable membrane device dialysate, mussel extract, as well as two artificial mixtures of the four pesticides were tested with standard toxicity and genotoxicity tests, including Microtox® (inhibition of bacterial luminescence), Daphtoxkit™, and Rotoxkit™ (toxicity tests with freshwater invertebrates Daphnia pulex and Brachionus calyciflorus, respectively), and sister chromatid exchange in human lymphocytes in in vitro assay. Results of these tests suggest that integration of the SPMD technique and bioassays may be a valuable approach for the assessment of levels and effects of bioavailable hydrophobic pollutants.

Removal of Pesticides from Water Using Hypercrosslinked Polymer Phases: Part 3— Mini-Column Studies and the Effect of Fulvic and Humic Substances

The adsorption of pesticides onto activated carbon and Hypersol-Macronet TM polymers has been compared in small-scale mini-column tests. The adsorption of simazine, chlorotoluron, isoproturon, atrazine and diuron onto hypercrosslinked polymers is selective. Isoproturon is the most preferred pesticide, followed by the sequence: diuron, atrazine, chlorotoluron and simazine. Adsorption of the pesticides appears to be controlled by hydrophobic interactions and hydrogen bonding with the surface of the polymer matrix. The pesticide adsorption capacity of Chemviron F-400 activated carbon is significantly greater than the polymeric adsorbents in the absence of fulvic acid. However, the adsorption capacity of the polymeric adsorbents is only slightly reduced in the presence of 20 mg l –1 fulvic acid whereas there is a very pronounced decrease in pesticide uptake with Chemviron F- 400 under similar conditions. This is explained in relation to the physical and chemical properties of the materials.

Pesticide volatilization and exposure of terrestrial ecosystems

Field experiments in cereals were carried out by herbicide and fungicide post emergence application in spring and by insecticide and fungicide treatment of barley before ripeness in summer. The pesticide concentrations in plants and soil of the target area and in the air above the field and concentrations in different distances to the treated field in front of and behind the hedge situated downwind were determined. After treatment in spring fenpropimorph occurred in the air in concentrations up to 1.3 μg/m 3; parathionethyl reached concentrations up to 3.3 μg/m 3 in the air after application in summer. The pesticide discharge in the main wind direction could be estimated assuming a pesticide transport with the average downwind wind speed and an average pesticide concentration at the field edge. While the total amounts of herbicide and fungicide discharges were low during the treatment in spring, the downwind discharge of the insecticide parathion-ethyl was 16–17 % of the applied amount in summer 1995. To assess the exposure of terrestrial ecosystems the pesticide uptake by standardized grass cultures and of leaves of the natural hedge situated downwind was determined. It was demonstrated that both, fenpropimorph uptake by plants after application in spring and chlorothalonil uptake by plants after application in summer resulted in high concentrations in non target plants. Here, the climatic parameters play an important role. However a significant accumulation of fenpropimorph and chlorothalonil did not take place in the grass cultures. As fenpropimorph concentrations in the target plants were low and decreased rapidly, 6–10 h after application no significant differences between the fenpropimorph concentrations in the target plants and in the grass cultures were determined.

Root Uptake and Xylem Translocation of Pesticides from Different Chemical Classes

A pressure-chamber technique was used to study the root uptake and xylem translocation of some fungicides, herbicides and an insecticide from different chemical classes in detopped soybean roots. Physiological parameters such as K+ leakage from roots, K+ concentrations in the xylem sap, and protein and ATP levels in the root cells were measured so as to evaluate any potential damage of this technique to the root system. HPLC was used to quantify the compounds in the xylem sap. The pressure-chamber technique has proved useful to study the root uptake and translocation of pesticides, does not damage the root system, and allows one to obtain appreciable volumes of xylem sap that can be analysed directly by HPLC, thus avoiding dependence on the availability of radio-labelled compounds. The concentration of each pesticide in the xylem sap showed a steady-state kinetic profile. Non-linear regression analysis was used to calculate the steady-state concentration and the time required to achieve 50% of the steady-state concentration (TSSC50). TSSC50 was well correlated with log Kow; the more lipophilic the compound the more time was required to reach the steady-state concentration. The efficiency of translocation was assessed by the transpiration stream concentration factor (TSCF) and a non-linear relationship between TSCF and log Kow was observed. The highest TSCF values were measured for those compounds with log Kow values around 3, a lipophilicity value similar to that reported earlier in an analogous experiment with detopped soybean plants but slightly higher than that reported in earlier experiments with intact barley plants. Lower TSCF values were obtained with chemicals with log Kow values below as well as above 3. © 1997 SCI.

Uptake of Organochlorine Pesticides by Solvent-Filled Cellulose and Polyethylene Membranes

Membrane-based passive samplers were used to study the uptake of organochlorine pesticides (lindane, aldrin, dieldrin, and chlorpyriphos) in a continuous-flow system. The membranes were filled with cyclohexane and a mixture of cyclohexane and triolein. Uptake of the chemicals was 24–84 times faster in polyethylene membranes compared to that in cellulose membranes. This is a clear indication that polar cellulose membrane hinders the transport of lipophilic compounds. Though uptake rates in polyethylene membranes were much higher, they were unable to retain the receiving solvent for longer time periods. The diffusion rate of chemicals through polyethylene membranes was dependent not only on their lipophilicity but their molecular mass as well.

Benzo[a]pyrene hydroxylase and glutathione s‐transferase activities as biomarkers in Lymnaea palustris (mollusca, gastropoda) exposed to atrazine and hexachlorobenzene in freshwater mesocosms

AbstractFreshwater pond mesocosms were used to validate xenobiotic‐metabolizing enzymes as biomarkers of contamination by atrazine and hexachlorobenzene (HCB) in a basommatophoran gastropod, Lymnaea palustris (Müller). Over long‐term (21‐d) exposure to 5, 25, and 125 μg/L atrazine and to 0.5, 1.25, and 5 μg/L HCB, the uptake and internal concentration of both pesticides were followed, and the activities of benzo[a]pyrene hydroxylase (BaPH) and glutathione S‐transferases (GSTs) of pesticide‐exposed snails were compared with those of control animals maintained in untreated mesocosms. Internally recovered HCB concentrations were much higher than internal atrazine concentrations, but the uptake of atrazine was faster than that of HCB. Although it affected the integrity of microsomal membranes, HCB had no relevant effects on BaPH and GST activities at concentrations which affected growth and fecundity, thus confirming the low inducibility of mollusc xenobiotic‐metabolizing enzymes by chlorinated compounds. In contrast, atrazine markedly inhibited BaPH and both postmitochondrial and cytosolic GSTs at the same concentrations, which had no effects on growth or reproduction. Enzyme inhibition was negatively correlated with the maximal internal amount of atrazine and positively correlated with the bioconcentration factor, suggesting that effects on xenobiotic‐metabolizing enzymes may affect pharmacokinetics of atrazine within the snail body. Correlation between the bioconcentration factor and enzyme inhibition may serve as a descriptor of the physiological status of animals and can also be used to indirectly estimate the pesticide concentration in the environment. Laboratory data were considered for the interpretation of results obtained in the mesocosms. In the biomarker context, BaPH and GST activities are proposed, along with other biochemical markers already identified in atrazine‐ and HCB‐exposed L. palustris, as elements of a multiparametric approach of the ecotoxicological effects of pesticides on freshwater ecosystems.

Pesticide uptake and locomotor behaviour in the woodlouse: an experimental study employing video tracking and 14C-labelling

: The toxicity of soil pesticide residues to target and non-target organisms depends on the amount of chemical absorbed by the organism. One of the principle factors governing chemical uptake is the amount of chemical encountered by the animal and, hence, the area of soil contacted. This in turn, depends on the locomotor behaviour of the animal. In the present study, the relationship between the uptake of soil residues of an organophosphate insecticide and locomotor behaviour was examined, employing (14)C-labelled dimethoate and computer-aided video tracking. Groups of male woodlice, Porcellio scaber (Isopoda), walked freely for 22 h on a soil substrate treated with three application rates of the pesticide. A strong correlation was found between pesticide uptake and path length, mean velocity and time spent in locomotor acivity, which is consistent with previously reported modelling studies. Our data suggest a linear relationship for all locomotor parameters except for path length at the highest application rate, where uptake was best described by an inverse exponential relationship. All doses induced hyperactivity in terms of time spent in locomotor activity. However, when compared with a untreated control group, the most pronounced effects were displayed at the lowest dose where path length, mean velocity and turning rate were also significantly different. The number of shifts between locomotor active and inactive periods in the experimental period increased with increasing application rate.

Modeling of foliar uptake and degradation of pesticides using crop growth model

A crop growth based model is developed with the target to estimate the redistribution of the foliar applied pesticides on/into plants. The model assumes pesticides penetration in according with the hypothesis of passive transport and first order degradation on/into plant. It integrates the effects of the pesticides physico‐chemical properties and treated plants morphological peculiarities as well as growth conditions. Consideration of the cuticle as separating compartment permits to estimate the accumulation of the pesticides into cuticle in dependence on its structure. Within this framework the model is reduced to analytical expression permitting to estimate the influence of pesticides decompositions rates and water content in the leaf tissue on the degree of its penetration.

The importance of the exposure route when testing the toxicity of pesticides to saprotrophic isopods

AbstractWhen effects of pesticides are tested on nontarget invertebrates, substrate exposure is mostly used. Routes of uptake of pesticides by saprotrophic invertebrates may, however, also occur through the food, since the litter layer will be their main food source. These organisms live in close contact with the soil surface and litter layer. The ecotoxicity of the pesticides benomyl, carbofuran, and diazinon was investigated in a series of experiments. The toxicity was tested in lethal concentrations (leading to LC50 estimations), and sublethal concentrations leading to no‐observed‐effect concentration (NOEC) estimations on growth. Both substrate and dietary exposure were used to evaluate the most critical exposure route for each case. For food exposure, the chemicals were offered in ground leaves, while for substrate exposure the test organisms were kept on treated sand. Experiments were done with the tropical isopodPorcellionides pruinosus.For all three pesticides, substrate exposure was more critical than dietary exposure. The LC50 values (active ingredient per dry mass of food or soil) for benomyl, carbofuran, and diazinon, when mixed with food, were >31,000, 485, and 74.15 μg/g, respectively, and when mixed with sand 1,221, 21.41, and 3.03 μg/g, respectively. Sublethal effects on body growth were found for benomyl (NOEC = 1,000 μg/g) and diazinon (NOEC = <8.71 μg/g) after dietary exposure, but no effects were found in the course of the experiment for substrate exposure. Based on the results, it is concluded that the exposure route is of great importance for determining lethal effects as well as sublethal effects of pesticides on nontarget invertebrates in soil. The most critical exposure route depends both on the mode of action of the chemical and on the toxicological end point considered.

Modelling pesticide fate with GLEAMS

The pesticide component of GLEAMS (Groundwater Loading Effects of Agricultural Management Systems) model was developed to evaluate the complex interrelationships among pesticide and soil properties, management alternatives, and climate using long-term simulations. GLEAMS resulted from an enhancement of the CREAMS model to allow simulation of pesticide transport within and through the plant root zone in addition to transport in surface runoff from field-sized areas. The pesticide submodel is operated with daily inputs from the hydrology and soil erosion sub-models. Pesticide input parameters are required to specify application rates, dates and methods and the properties of the chemical. Outputs are pesticide concentrations and mass in runoff water and attached to transported sediments, pesticide mass leached below the root zone, and pesticide distribution with depth in the root zone. Multiple applications of up to 10 different pesticides can be simulated simultaneously for periods of up to 50 years. The model also considers pesticide metabolites produced by sequential first-order reactions and plant uptake of pesticides. Application methods simulated may be soil surface application, soil incorporation, soil injection, foliar application, or through irrigation water. Values for pesticide soil half-life, foliar half-life, foliar wash-off potential, solubility, and Koc (sorption coefficient for soil carbon) may be obtained from the internal data base or supplied by the user if more specific information is available.

STUDY OF APPLICATION OF FUGACITY MODEL TO BIOMONITORING OF CHROLONITROPHEN

In recent years, a large number of pesticides have been produced and discharged into the resources of water supply. The data on their bioconcentration and excretion by aquatic lives are useful for the evaluation of their safety to man and their contamination of fishes in lake, river and sea. Fugacity model is developed for calculating the concentration of pesticides in a simple generic foodchain. Pesticide uptake efficiency from water, excretion rate, and chemical assimilation efficiency are variable as a function of the octanol-water partition coefficient, Kow. The model indicates the significance of the growth rate and variable efficiency of uptake in calculation of the bioaccumulation factor BAF under field condition. Food chain effects are not significant up to log Kow of-5. For logKow of 5-7, calculated and obserbed field concentration factors in benthic organisms indicate significant elevations above calculated field BAF value.The analysis was made by using the data at 30 stations in the river of Fukui Pref., for the purpose of suporting the monitoring by aquatic lives as indicator for contamination of CNP and the application of Fugacity Model to the monitoring results.

Organochlorine pesticide exposure and uptake following soil treatment of domestic premises

Twenty‐nine dwellings treated with aldrin, an organochlorine (OC) pesticide, in a standard manner for prevention of termite infestation, were repeatedly sampled over a two‐year period for airborne aldrin concentrations. Air sampling was carried out under standardized conditions in an unventilated room. Periodic measurements were also made of blood dieldrin levels of one occupant of each dwelling. In ten of the dwellings there was no detectable airborne aldrin prior to treatment. After treatment aldrin concentration varied from 0.08 to 51 μg m‐3. One week following treatment, six dwellings had levels above 10 μg m‐3; by six months only two dwellings were above this level. After one year, only one dwelling had an aldrin concentration above this level (27 μg m‐3) and the concentration in that dwelling was still nearly the same after two years. This dwelling was also sampled three years post‐treatment, by which time the concentration had declined to 12 μg m‐3. Statistical analysis of the blood dieldrin levels...

Modelling the fate of organic chemicals in the soil plant environment: Model study of root uptake of pesticides

The fate of organic chemicals in the soil-plant-atmosphere environment and the governing processes were studied with a coupled dynamic soil transport and plant compartment model. Scenarios with applications of pesticides on sand and loam soils with chemical uptake in barley and wheat were used in the model calculations. Root uptake and concentrations in the plant compartments stem, leave and fruit were calculated for the pesticides terbuthylazine, isoproturon and carbofuran. The effectivity of uptake from soils with different soil sorption coefficients had been shown for sand and loam soils. The processes degradation in plant and volatilization from leaves to atmosphere are especially effective for carbofuran and terbuthylazine. Although the concentrations in corn at harvest are lower than the maximum allowed concentrations, the peak concentrations in the course of the vegetation period are significantly higher (factor ≤ 200).

Mineralization and Uptake of Triazine Pesticide in Soil‐Plant Systems

Deep-rooted trees planted as a buffer zone can intercept runoff and eroded sediments, thus reducing non–point-source pollution due to agricultural chemicals. In this study, \IPopulus\N sp. were grown in bioreactors with an agricultural soil (silt-loam) and in a silica-sand media; both were spiked with ¹\u4C uniformly ring-labeled atrazine. The plants took up over 11% of the ¹\u4C labeled atrazine applied to the silt-loam soil and over 91% of that applied to the silica sand media, with the majority of the ¹\u4C accumulating as non-phytotoxic metabolites in the leaves. Research suggests that, in addition to nutrient uptake, poplar tree buffer strips may be effective in removing atrazine from agricultural percolation and runoff water.

Uptake of Atrazine by Hyphae ofGlomusVesicular-Arbuscular Mycorrhizae and Root Systems of Corn (Zea maysL.)

A system, including a specialized treatment vessel for pesticide uptake studies, was developed and experiments were carried out to determine the ability ofGlomus intraradices(Schenck & Smith),G. vesiculiferium(Thaxter), and indigenous vesicular-arbuscular mycorrhizae (VAM) fungi to influence14C-atrazine uptake and transfer to corn. Uptake by root systems with and without VAM infection was compared to uptake by VAM hyphal systems by controlling access to14C-atrazine-treated soil. Hyphal systems ofGlomusspecies were able to remove14C-residue from soil and transfer these to corn. Amount of14C-residue transferred to corn through hyphal systems was highly correlated to the level of VAM root infection which varied among VAM species. In root systems, variations in14C-residue uptake resulting from mycorrhization were largely explained in terms of the negative correlation between level of infection and root mass located in14C-atrazine-treated soil. Allocation of14C-residue to shoot tissues of corn was greater when14C-residues were taken up through root systems rather than through hyphal systems. There were significant effects of VAM species on14C-residue compartmentalization between methanol extractable and nonextractable portions of corn tissues. Data from these experiments in a confined soil system were related to VAM cost-benefit relationships and indicate a significant role for VAM in determining atrazine fate in agricultural systems.

Analysis of foliar uptake of pesticides in barley leaves: Role of epicuticular waxes and compartmentation

AbstractUptake of pesticides into barley leaves was measured under controlled conditions. Leaves detached from plants were submerged in aqueous solutions of 14C‐labelled (2,4‐dichlorophenoxy)acetic acid, triadimenol, bitertanol and pentachlorophenol. Uptake was biphasic. A short (30‐min) period with high rates of uptake was followed by uptake that proceeded more slowly and was steady over hours. Compartmentation of pesticides was studied by desorbing pentachlorophenol from leaves previously loaded with [14C]pentachlorophenol. From the uptake and desorption kinetics it was concluded that penetration of pesticides proceeds as follows: the compounds are first sorbed at the surface of epicuticular wax aggregates where they are in contact with the donor solutions. Solutes then diffuse through the surface wax aggregates into the cuticle. Equilibrium between donor solutions, surface wax and cuticle is established in about 30 min. After this time the amounts of solutes in these compartments no longer increase. Uptake after this time represents penetration into the leaf cells. This fraction of the pentachlorophenol is retained irreversibly, while that sorbed in wax and cutin can be desorbed again. All compounds were sorbed in cuticular waxes and partition coefficients wax/water were determined. On a mass basis only 5 to 10% of the amounts sorbed in cutin are sorbed in wax. This comparatively low solubility in wax contributes to the barrier properties of cuticular waxes. The other determinant of permeability is the very low mobility of solutes in cuticular waxes.

Determination of mobilities of organic compounds in plant cuticles and correlation with molar volumes

AbstractMobilities of selected pesticides in plant cuticles have been measured using unilateral desorption from the outer surface (UDOS). The outer layer of the cuticle limits the rate of foliar uptake and solute mobilities in this layer have been determined. The primary parameter measured was the first‐order rate constant of desorption. From these rate constants, permeances, half‐times of penetration and diffusion coefficients could be calculated. Rate constants were lowest in bitter‐orange (Citrus aurantium L.) leaf cuticles and this cuticle turned out to be very size‐selective, as rate constants decreased by a factor of 264 when molar volumes increased by only a factor of about three. Rate constants measured using green‐pepper (Capsicum annuum L. cv. Bell Boy) fruit cuticles were larger by one to two orders of magnitude and this cuticle was considerably less size‐selective. A good correlation between rate constants and molar volumes was observed for cuticles from both plant species, which means that rate constants can be estimated from molar volumes of pesticides. Rate constants of desorption are mobility parameters which do not depend on lipophilicity of solutes. Thus, it is now possible to separate the contributions of mobilities and solubilities in cuticles to rates of foliar uptake of pesticides.

Uptake and elimination kinetics of organophosphorous pesticides in the guppy (poecilia reticulata): Correlations with the octanol/water partition coefficient

AbstractBioconcentration factors, uptake rate constants and elimination rate constants of a series of organophosphorous pesticides were determined in the guppy (Poecilia reticulata). The results of these three toxicokinetic parameters were related to measured octanol/water partition coefficients (Kow). A simple one‐compartment model fitted the uptake and elimination characteristics of the chemicals. A biphasic relationship was observed between log k1 (uptake rate constant) and log Kow, whereas elimination rate constants were inversely related to Kow. For some of the test compounds substantially higher elimination rates were found, compared to isolipophilic chlorobenzenes, which resulted in lower bioconcentration factors. This divergent behavior is discussed in view of possible biotransformation reactions for these compounds.

Bioconcentration of endosulfan in different body tissues of estuarine organisms under sublethal exposure

The organochlorine pesticide endosulfan is applied in the agricultural fields as liquid in India. Investigations have revealed the occurrence and distribution of endosulfan in both biotic and abiotic components of Vellar estuary. The results from static bioassay studies revealed that fishes were more susceptible to the organochlorine pesticides than mollusks. Though the available information on the uptake of endosulfan by the estuarine organisms are limited to whole body tissues, no attempt has been made to find out the extent of uptake of pesticides by the different body tissues of the estuarine organisms. Hence the present study was planned to determine the bioconcentration of endosulfan in different tissues of fishes Mugil cephalus, Mystus gulio, oyster Crassostrea madrasensis and clam Katelysia opima based on the measured concentration of endosulfan in the experimental medium of the continuous flow through system for a period of 10 d.

Trends in the formulation of pesticides—an overview

AbstractThe customer increasingly requires safer and more convenient pesticide formulations. Emulsifiable concentrates and wettable powders are nowadays viewed less favourably by farmers and registration authorities. Suspension concentrates are now common and water‐dispersible granules and emulsions in water are receiving increasing attention. Capsule suspensions offer both safer and more effective performance in favourable cases. For convenience the farmer requires multi‐component products, either as mixtures of active ingredients, which might be as suspoemulsions, or with built‐in enhancing surfactants and oils. Seed treatments are now required as aqueous suspensions and the seed is increasingly of interest as an eficient carrier for pesticides. Research into biological control agents sets the difficult challenge of formulating these products as viable organisms. Three examples of developments are described. These are the applications of polymeric surfactants for suspension concentrates and suspoemulsions, studies of enhancement of pesticide uptake with surfactants and developments in microencapsulation.