RESUMEN
Assessment and management of issues related to pesticide residues, such as environmental fate, monitoring and toxicity, are complex and, in many cases, require costly studies. The early establishment of a priority list of pesticides that should be monitored and assigned to a restricted-use policy is an important issue of post-registration Risk Assessment (RA). Various pesticide registration approaches have been adopted by different countries with those from Europe and the USA being the most popular, constituting the major prototypes for registration approaches in other countries. Adoption of pesticide registration and monitoring systems developed in Europe or USA by Latin American and Caribbean countries may underestimate factors affecting the environmental fate and toxicity of pesticides in their own countries. Incentive for this short review was the activities undertaken during the three KNOWPEC workshops held in Costa Rica, Argentina and Bolivia where European pesticide experts met Latin American experience in the form of Costa Rica's exceptional environmental conditions and ecology, Argentina's and Uruguay's soyisation and Bolivia's contrasting climate and agricultural zones. During the parallel activities of the workshop - including scientific presentations, field trips, interviews and meetings among European partners and pesticide stakeholders in Latin America, - the whole pesticide chain (import-export, trade, application, plant protection-efficacy, residues, monitoring, remediation and risk) was studied and clarified. Recently-published chemical prioritization studies were reviewed to consider their use as a tool to support risk assessments. Differences in regional practices are highlighted as regards to the establishment of RA or prioritization strategy in European and Latin American regimes. General guidance of establishing a cost-effective pesticide monitoring scheme in water bodies of Latin America and the Caribbean (LAC) is also proposed. Moreover, we summarize the most important factors that should be taken into consideration for prioritization approaches and categorization used in pesticide environmental monitoring studies. Consideration of current RA approaches and limitations, and pesticide prioritization exercises highlighted in this Commentary could assist in the management of pesticides in Latin America and Caribbean.
Asunto(s)
Plaguicidas , Argentina , Región del Caribe , Monitoreo del Ambiente , Europa (Continente) , América Latina , Plaguicidas/análisisRESUMEN
Dichlorvos (DDVP) is an organophosphorus pesticide that has been classified as highly hazardous chemical by the World Health organization. In this study, the fate of the pesticide DDVP in natural water compartments was examined under simulated sunlight. Moreover, the effect of UV-254 irradiation on DDVP depletion was also studied. In deionized water, DDVP was photodegraded only in the presence of dissolved molecular oxygen. The photodegradation during the first 6â¯h of sunlight irradiation occurred with pseudo first-order kinetics, and the rate constants were 0.040â¯h-1 at pHâ¯7 and 0.064â¯h-1 at pHâ¯3. A reaction mechanism for the generation of reactive oxygen species (ROS) via DDVP photoabsorption was proposed. Humic acids (HA) played a double role as photosensitizer and inhibitor, observing an enhancement on DDVP photodegradation at low HA concentration (TOCâ¯=â¯2â¯mgâ¯L-1). The depletion of DDVP under 254â¯nm UV irradiation was ascribed to direct photodegradation and oxygen mediated photoinduced reactions. Direct photodegradation of DDVP decreased with 254â¯nm irradiation reduction, highlighting the importance of radical mediated mechanisms at low irradiation doses. Based on LC/MS data, the main photoproducts under simulated solar light and UV-C irradiation were identified and potential reaction pathways were postulated. The three main identified products were o-methyl 2,2-dichlorovinyl phosphate, dichloroacetaldehyde and dimethylphosphate. Moreover, the toxicity of samples was evaluated along the irradiation exposure time using Microtox® assays. This study brings new insights into the role of oxygen in the photodegradation of DDVP and the induced and inhibition mechanisms involved in the presence of the humic acids in natural waters.
RESUMEN
Diclofenac (DCF), a common analgesic, anti-arthritic and anti-rheumatic drug, is one of the most frequently detected compounds in water. This study deals with the degradation of diclofenac in aqueous solution by ozonation. Biodegradability (BOD(5)/COD ratio and Zahn-Wellens test), acute ecotoxicity and inhibition of activated sludge activity were determined in ozonated and non-ozonated samples. Liquid chromatography coupled with time-of-flight mass spectrometry (LC/TOF-MS) was used to identify the intermediates formed in 1 h of ozonation. Eighteen intermediates were identified by these techniques and a tentative degradation pathway for DCF ozonation is proposed. Experimental results show that ozone is efficient at removing DCF: >99% removal (starting from an initial concentration of 0.68 mmol L(-1)) was achieved after 30 min of ozonation (corresponding to an absorbed ozone dose of 0.22 g L(-1), which is 4.58 mmol L(-1)). However, only 24% of the substrate was mineralized after 1 h of ozonation. The biodegradability, respiration inhibition in activated sludge and acute toxicity tests demonstrate that ozonation promotes a more biocompatible effluent of waters containing DCF.