Lower tier toxicity risk assessment of agriculture pesticides detected on the Río Madre de Dios watershed, Costa Rica.

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.

Use of cholinesterase activity as a biomarker of pesticide exposure used on Costa Rican banana plantations in the native tropical fish Astyanax aeneus (Günther, 1860).

In Costa Rica, thousands of tones of agricultural pesticides have been used for decades and their use is continuously increasing due to intensive and expanding production of coffee, pineapple, rice, ornamental plants and bananas. The objective of this study was to evaluate whether choline esterase (ChE) activity could be used as a biomarker of exposure to pesticides in the Costa Rican native fish Astyanax aeneus (characidae). Three methods used in order to evaluate the ChE biomarker were as follows: Laboratory studies where A. aeneus was exposed to organophosphate pesticide (ethoprophos); In situ 48 hr exposure assessment using caging experiments with fish exposed upstream and downstream of banana plantations and ChE activity estimation of in fish captured directly at sites with different degrees of pesticide exposure. Results from the laboratory studies showed that ChE activity in both brain and muscle tissue was significantly lower in fish exposed to ethoprophos than in controls. Fish from the caging experiments showed no difference in ChE activity neither in brain nor in muscle tissue between the four tested sites and was attributed to the short duration of the exposure. Asignificant difference in ChE activity was determined in muscle of fish captured from Laguna Madre de Dios compared to fish from Canal Batán. Although our laboratory results revealed that ChE activity in A. aeneus was highly responsive to ethoprophos, results from field experiments were less conclusive and showed that the captured fish showed large variability in ChE activity and that more research is needed before ChE activity can be used as reliable biomarker of pesticide exposure.

Rhabdoid tumor: an unusual pediatric brain tumor

Rhabdoid tumors of the brain are rare with an invariable dismal prognosis despite treatment. This is the case of a 3 year old boy who presented lethargy, somnolence, nausea, vomiting, and headaches one week prior to hospitalization. A posterior fossa tumor with hydrocephalus was noted on a head computed tomography (CT) scan. A ventriculoperitoneal shunt was placed with subsequent gross total tumor resection. Pathology findings were those of a rhabdoid tumor. The histopathology, immunohistochemistry and ultrastructure of this unusual pediatric cerebral neoplasia is discussed.

Cerebral hemiatrophy: an associated finding in an epileptic child

Cerebral hemiatrophy is a rarely occurring condition of different etiologies that can be regarded as the final stage of a number of different disease processes. It is characterized by a marked asymmetry of the cerebral hemispheres. A 12 year old girl with history of epilepsy since infancy and psychomotor delay presented in status epilepticus, developed marked cerebral edema, bilateral uncal herniation and bilateral infarcts of the posterior cerebral artery territories. Autopsy findings revealed left cerebral hemiatrophy as an incidental findings. The clinicopathologic features and classification of this entity are discussed.

Overview of results from the WaterTox intercalibration and environmental testing phase II program: Part 1, statistical analysis of blind sample testing.

There is an urgent need to evaluate the presence of toxicants in waters used for human consumption and to develop strategies to reduce and prevent their contamination. The International Development Research Centre undertook an intercalibration project to develop and validate a battery of bioassays for toxicity testing of water samples. The project was carried out in two phases by research institutions from eight countries that formed the WaterTox network. Results for the first phase were reported in the special September 2000 issue of Environmental Toxicology. Phase II involved toxicity screening tests of environmental and blind samples (chemical solutions of unknown composition to participating laboratories) using the following battery: Daphnia magna, Hydra attenuata, seed root inhibition with Lactuca sativa, and Selenastrum capricornutum. This battery was also used to assess potential toxicity in concentrated (10x) water samples. Results are presented for a set of six blind samples sent to the participating laboratories over a 1-year period. Analyses were performed for each bioassay to evaluate variations among laboratories of responses to negative controls, violations of test quality control criteria, false positive responses induced by sample concentration, and variability within and between labs of responses to toxic samples. Analyses of the data from all bioassays and labs provided comparisons of false positive rates (based on blind negative samples), test sensitivities to a metal or organic toxicant, and interlaboratory test variability. Results indicate that the battery was reliable in detecting toxicity when present. However, some false positives were identified with a concentrated soft-water sample and with the Lactuca and Hydra (sublethal end-point) tests. Probabilities of detecting false positives for individual and combined toxic responses of the four bioassays are presented. Overall, interlaboratory comparisons indicate a good reliability of the battery.

Overview of results from the WaterTox intercalibration and environmental testing phase II program: part 2, ecotoxicological evaluation of drinking water supplies.

Because of rapid population growth, industrial development, and intensified agricultural production increasing amounts of chemicals are being released into the environment, polluting receiving water bodies around the world. Given the potential health risk associated with the presence of toxicants in water sources used for drinking yet the scarcity of available data, there is a need to evaluate these waters and develop strategies to reduce and prevent their contamination. The present study examined the applicability of a battery of simple, inexpensive bioassays in environmental management and the relevance of the test results in establishing the toxicological quality of water sources and drinking water within the framework of the eight-country WaterTox Network, sponsored by the International Development Research Centre, Ottawa, Canada. Seventy-six samples were collected from surface and groundwater sources and seven samples from drinking water treatment plants. Each sample was tested with a core battery of bioassays (Daphnia magna, Hydra attenuata, and Lactuca sativa root inhibition tests) and a limited set of physical and chemical parameters. In addition, three labs included the Selenastrum capricornutum test. When no toxic effects were found with the battery, samples were concentrated 10x using a solid-phase extraction (SPE) procedure. Nonconcentrated natural water samples produced a toxic response in 24% of cases with all three core bioassays. When all bioassays are considered, the percentage of raw samples showing toxicity with at least one bioassay increased to 60%. Of seven treated drinkingwater samples, four showed toxicity with at least one bioassay, raising the possibility that treatment processes in these instances were unable to remove toxic contaminants. The Daphnia magna and Hydra attenuata tests indicated a high level of sensitivity overall. Although only three of the eight countries used S. capricornutum, it proved to be an efficient and reliable bioassay for toxicity assessment.