Environmental fate of dibutylphthalate in agricultural plastics: Photodegradation, migration and ecotoxicological impact on soil.

Phthalic acid esters (PAEs) were determined in polyethylene covers used in horticultural production units located at Moreno and La Plata districts (Buenos Aires, Argentina), detecting 0.69-8.75 mg PAEs kg-1 plastic in greenhouse and tunnel films. The PAEs found were diisobutylphthalate (DIBP), dibutylphthalate (DBP) and diethylhexylphthalate (DEHP). DBP was chosen as a model molecule to carry out the photochemical degradation studies that led to the formation of monobutylphthalate (MBP) and phthalic acid (PA). DBP, MBP and PA migration from plastic covers was studied, finding that while DBP and MBP moved to soil and atmosphere in short times (<48 h), PA remained in the agricultural covers. Further experiments with DBP were made to explore the effect on migration of temperature (20 °C, 50 °C), film thickness (25 µm, 100 µm) and plastic ageing by solarization, observing that temperature increase, film thickness reduction and ageing by solarization favored DBP migration to the environment. DBP and MBP impact on soil were evaluated by avoidance and reproduction tests using Eisenia andrei as bioindicator. Both compounds reduced cocoon viability decreasing the number of juveniles at the lowest concentration assayed (0.1 mg kg-1 of soil). At higher DBP and MBP concentrations the reproductive parameters (number of total cocoons, hatchability and number of juveniles) also showed alterations compared with the controls. Carboxylesterases (CaE), cholinesterases (ChE) and glutathion-S-transferases (GST) activities were analyzed in E. andrei exposed to DBP; cholinesterases activities were reduced at 1 and 10 mg DBP kg-1 soil, and glutathione S-transferases activities were increased at 10 mg DBP kg-1 soil while no effect was observed on carboxylesterases activities. These results emphasize the need to continue studying the impact of PAEs and their photodegradation products on the environment.

Human exposure and mass balance distribution during procymidone application in horticultural greenhouses.

The purpose of this study was to analyze the impact of procymidone application in periurban horticultural greenhouses, especially on workers (applicators and assistants) and soil and plastic mulching, when mechanically pressurized application systems were employed. The mean Potential Dermal Exposure (PDE) was measured using the Whole Body Dosimetry technique. The PDE for the applicators was 188 mL h-1 ± 103 mL h-1, and 14.7 mL h-1 ± 6.3 mL h-1 for the assistants. In the first case, the most exposed body sections were the upper right and left (46.8 mL h-1 ± 23.4 mL h-1; 47.0 mL h-1 ± 23.5 mL h-1) and lower (20.8 mL h-1 ± 10.4 mL h-1; 17.3 mL h-1 ± 8.7 mL h-1) legs, while in the case of assistants, hands and legs were the most impacted limbs. Regarding the Margin of Safety (MOS) during the mix and load stage, two of three pesticide preparations resulted unsafe, while for the applicators, six of six spraying operations were unsafe. For the assistants, five of five operations were safe, but three of them were close to the safety limit. Procymidone distribution between drift (0.03% ± 0.07 %), applicator (0.20% ± 0.15 %), polyethylene mulching (8.5% ± 4.5 %) and soil (3.0% ± 1.1 %) was determined with respect to the total pesticide applied. Procymidone soil impact was also evaluated using Eisenia andrei behavioral tests, finding positive correlations between procymidone application and avoidance and reproduction tests.

Human and soil exposure during mechanical chlorpyrifos, myclobutanil and copper oxychloride application in a peach orchard in Argentina.

The objective of this study was to measure the impact of the mechanized chlorpyrifos, copper oxychloride and myclobutanil application in a small peach orchard, on humans (operators, bystanders and residents) and on the productive soil. The mean Potential Dermal Exposure (PDE) of the workers (tractor drivers) was 30.8mL·h-1±16.4mL·h-1, with no specific pesticide distribution on the laborers body. Although the Margin of Safety (MOS) factor for the application stage were above 1 (safe condition) for myclobutanil and cooper oxycloride it was below 1 for chlorpyrifos. The mix and load stage remained as the riskier operation. Pesticide found on the orchard soil ranged from 5.5% to 14.8% of the total chlorpyrifos, copper oxychloride and myclobutanil applied. Pesticide drift was experimentally measured, finding values in the range of 2.4% to 11.2% of the total pesticide applied. Using experimental drift values, bystander (for one application), resident (for 20 applications) and earthworm (for one application) risk indicators (RIs) were calculated for the chlorpyrifos plus copper oxychloride and for myclobutanil treatments for different distances to the orchard border. Earthworm RI was correlated with experimental Eisenia andrei ecotoxicological assays (enzymatic activities: cholinesterases, carboxylesterases and glutathione S-transferases; behavioral: avoidance and bait-lamina tests) with good correlation.

Polyethylene film incorporation into the horticultural soil of small periurban production units in Argentina.

Horticulture makes intensive use of soil and extensive use of polyethylene (PE) sheeting and pesticides, producing an environment where the dynamics between soil and plastics can affect pesticide fate. We have determined that the presence of plastic residues in the horticultural soil of small production units equals 10% of the soil area, being meso and macro-sections the predominant fragment sizes. All soil samples were taken from different plots located in Cuartel V, Moreno district, in the suburbs of Buenos Aires city, Argentina. Laboratory experiments were conducted to see the relations among pesticide, soil and PE film. Endosulfan recovery from LDPE films (25µm and 100µm) was studied, observing evidence that indicated migration to the inside of the plastic matrix. To further analyze the dynamics of pesticide migration to soil and atmosphere, experiments using chlorpyrifos, procymidone and trifluralin were performed in soil-plastic-atmosphere microenvironments, showing that up to 24h significant amounts of pesticides moved away from the PE film. To determine whether PE residues could act as potential pesticide collector in soil, column elution experiments were done using chlorpyrifos, procymidone and trifluralin. Results showed an important pesticide accumulation in the mulch film (584µg-2284µg pesticide/g plastic) compared to soil (13µg-32µg pesticide/g soil). Finally, chemical and photochemical degradation of deltamethrin adsorbed in PE film was studied, finding a protective effect on hydrolysis but no protective effect on photodegradation. We believe that a deeper understanding of the dynamics among soil, plastic and pesticides in horticultural productive systems may contribute to alert for the implications of PE use for plastic sheeting.

Pesticide potential dermal exposure during the manipulation of concentrated mixtures at small horticultural and floricultural production units in Argentina: the formulation effect.

Potential dermal exposure measurements of horticultural and floricultural field operators that handled concentrated pesticides showed a correlation with the types of formulations used (liquid or solid) during the mix and load stage. For liquid formulations, hand exposure was 22-62 times greater than that for solid ones. The dermal exposure mechanism was studied for this formulation under laboratory conditions, finding that the rupture of the aluminum seal of the pesticide container and the color of the liquid formulation are important factors. Additionally, significant external surface contamination of pesticide containers collected at horticultural farms was found. This could partially account for the differences between the exposure levels of field and laboratory experiments for liquid formulations.

Environmental pesticide distribution in horticultural and floricultural periurban production units.

The environmental pesticide distribution on non-target systems (soil, drift and agricultural plastics) during the application step at small periurban production units, was studied in open field and greenhouses, for different crops (tomato, lettuce, broccoli, strawberry and flowers) using different pesticides (endosulfan, procymidone, chlorothalonil, chlorpyrifos and deltamethrin). In all cases, soil was the most exposed non-target system. For greenhouses, a general pesticide distribution was found of approximately 2/3 for crop, 1/4 for soil and 1/20 for plastic, of the total amount applied. In horticultural open fields, although the distribution was very dependent on the crop size and type, soil was also the most exposed non-target subsystem. Pesticide drift seems not to be significant in these production units, whilst pesticide accumulation on agricultural plastics reached up to 45% of the total applied, for polyethylene mulching in strawberry fields.

Pesticide risk assessment in flower greenhouses in Argentina: the importance of manipulating concentrated products.

An evaluation of the Potential Dermal Exposure of workers to endosulfan and procymidone at the mix/load and application stages was done in small floricultural production units in Argentina. Seven experiments were performed with different operators under typical greenhouse conditions, based on the whole body dosimetry methodology. These results indicate that the mean Potential Dermal Exposure of the application step was 45.0 ± 55.0 mL h(-1) with the highest proportion on torso, head, arms and hands. When the mix/load and application stages were compared, the first was found to contribute the most to the total exposure. Also, the Margin of Safety for the different operations was calculated, and a pesticide surrogate was developed and used to make comparative evaluations of hand exposure for different groups of operators. These results emphasize the importance of the mix/load stage in the exposure process.

Potential dermal exposure in greenhouses for manual sprayers: analysis of the mix/load, application and re-entry stages.

An evaluation of the Potential Dermal Exposure for the mix/load, application and re-entry stages, associated with procymidone and deltamethrin usage, was carried out for tomatoes grown in greenhouses of small production units in Argentina. Eight experiments were done with four different operators, under typical field conditions with a lever operated backpack sprayer. The methodology applied was based on the Whole Body Dosimetry technique, evaluating a set of different data for the mix and load, application and re-entry operations. These results indicated that the Potential Dermal Exposure of the application step was (38+/-17)mLh(-1) with the highest proportion on torso, head and arms. When the three stages were compared, re-entry was found to contribute least towards the total Potential Dermal Exposure; meanwhile in all cases, except one, the mix/load operation was the stage with highest exposure. The Margin of Safety for each different operation was also calculated and the proportion of pesticide drift from the greenhouse to the environment is presented. These results emphasize the importance of improving the personal protection measures in the mix and load stage, an operation that is not usually associated with high-risk in small production units.

Potential dermal exposure to deltamethrin and risk assessment for manual sprayers: influence of crop type.

A comparison of the Potential Dermal Exposure (PDE) of workers to the insecticide deltamethrin was made as a function of crop type, in small agricultural production units in Argentina. Seven experiments were done with two different crops (maize and broccoli, treated area between 600 and 1000 m(2)) with three different operators under typical field conditions using a lever operated knapsack. The methodology is based on the whole body dosimetry technique, presenting separately the data for mixing/loading and application activities. These results indicate a higher concentration of pesticide in lower body sections for broccoli and a wider distribution for maize. The risk inherent in these agricultural procedures is estimated through Margin of Safety (MOS) values and was found to be generally safe. Preliminary results of a mass balance distribution of the pesticide between crop, soil and operator are also presented.

Analytical method for assessing potential dermal exposure to captan, using whole body dosimetry, in small vegetable production units in Argentina.

An analytical method has been developed that can be used to determine the potential dermal exposure (PDE) of workers to the pesticide captan in small-scale horticultural production units. The methodology is based on the whole body dosimetry technique, using a cotton coverall and cotton gloves as sampling media, with protective clothing worn beneath the cotton media to protect the operator. The quantitative determination of captan was done by gas chromatography-electron capture detector (GC-ECD), with the analytical method validated by measuring limits of detection and quantification, linear ranges, sample recovery and precision. Special emphasis is placed on factors that affected the stability of captan during chromatographic determination. The data generated for potential dermal exposure are presented separately for mixing/loading and application activities. These data are compared with values obtained with visible tracers using a similar field technique. Margin of safety (MOS) values are also calculated for the agricultural procedures studied.

Indigenous heavy metal multiresistant microbiota of Las Catonas stream.

Las Catonas stream (Buenos Aires Metropolitan Area) receives a complex mixture of pollutants from point and diffuse sources because of the agricultural, industrial and urban land uses of its basin. Widespread detection of heavy metals exceeding aquatic life protection levels has occurred in monitoring reconnaissance studies in surface and pore water. As a result of the screening of Cu, Cd, Zn and Pb resistant/tolerant and culturable microbiota, B101N and 200H strains (Pseudomonas fluorescens or putida) were isolated and selected for further studies. They showed 65% Cd and 35% Zn extraction efficiency from aqueous phase. The potential use of these strains in wastewater treatment is currently investigated in order to contribute to decrease heavy metal pollution, a problem affecting every stream of Buenos Aires Metropolitan Area.

Descripción del estado de las aguas de los arroyos Claro y Las Tunas en el triángulo industrial de Malvinas Argentina

Se presenta un estudio fisico-quimico del estado basal de los arroyos Claro y Las Tunas, ubicados en la Region Metropolitana Buenos Aires (RMBA). Ambos arroyos son de bajo caudal y poseen lenta velocidad, determinada por una topografia de pendiente suave. Los tramos superiores atraviesan zonas de media a alta densidad de poblacion, internandose luego en regiones donde se concentra una intensa actividad industrial

Descripción del estado de las aguas de los arroyos Claro y Las Tunas en el triángulo industrial de Malvinas Argentina

Se presenta un estudio fisico-quimico del estado basal de los arroyos Claro y Las Tunas, ubicados en la Region Metropolitana Buenos Aires (RMBA). Ambos arroyos son de bajo caudal y poseen lenta velocidad, determinada por una topografia de pendiente suave. Los tramos superiores atraviesan zonas de media a alta densidad de poblacion, internandose luego en regiones donde se concentra una intensa actividad industrial