Risk assessment of agriculture impact on the Frío River watershed and Caño Negro Ramsar wetland, Costa Rica.

The Caño Negro Ramsar wetland is a conservation area of great natural and societal value, located in the lower part of the Frío River watershed in the north of Costa Rica. Its aquatic ecosystems may be considered vulnerable to pollution due to recent changes in land use toward agriculture. In 2011 and 2012, quarterly sampling was done at ten sites located in the middle and lower sections of the Frío River Basin that pass through crop areas and later drain into Caño Negro wetland. Pesticide residues, nitrates, sediment concentrations, and diversity of benthic macroinvertebrates and fish biomarkers were studied in the selected sites. Additionally, risk of toxicity was calculated in two different ways: (1) by using a ratio of MEC to hazard concentrations threshold for 5% of species (HC5) to calculate a risk quotient (RQ), and (2) by using a ratio of MEC to available ecotoxicity data of native fish and cladocera for diazinon and ethoprophos, to obtain a risk quotient for native species (RQns). Results indicated that three out of the ten sites (rivers Thiales, Mónico, and Sabogal) showed variable levels of pollution including six different active ingredients (a.i.) of pesticide formulations (herbicides ametryn, bromacil, and diuron; insecticides cypermethrin, diazinon, and ethoprophos). Moreover, potential adverse effects on fishes in Thiales and Mónico rivers were indicated by cholinesterase (ChE) inhibition and glutathione S-transferase (GST) enhancement. Risk evaluations indicated pesticide residues of ametryn, bromacil, and ethoprophos to be exceeding the limits set by MTR, also RQ was high (>1) in 70% of the positive samples for diuron (most frequently found pesticide in water samples), cypermethrin, diazinon, and ethoprophos, and RQns was high for diazinon. Therefore, these substances might be of major concern for the ecological health of aquatic ecosystems in the middle basin of the Frío River. The most critical site was Mónico River, which had the highest pollution (75% detection samples with 3-5 a.i.) and highest calculated risk (RQ > 1 in 75% of the samples). This is also the river that most directly drains into the protected wetland. Even though pesticide pollution in this area is not as severe as in other parts of Costa Rica, it is imperative that measures are taken, particularly in the surroundings of Mónico River, in order to diminish and mitigate possible detrimental effects to biota in Caño Negro Ramsar Site.

Pesticide exposure on sloths (Bradypus variegatus and Choloepus hoffmanni) in an agricultural landscape of Northeastern Costa Rica.

Between 2005 and 2008, wild Bradypus variegatus and Choloepus hoffmanni inhabiting an agricultural landscape and captive animals from a rescue center in Northeastern Costa Rica were studied to assess exposure to pesticides. A total of 54 animals were sampled: 42 wild sloths captured at an agricultural landscape and 12 captive animals from a rescue center. Pesticides' active ingredients were determined in three sample matrices: hair, aqueous mixture (paws' wash) and cotton gauze (mouth clean) based on multi-residue gas chromatography methods. Recoveries tests ranged from 73 to 146% and relative standard deviations were less than 20% throughout all the recovery tests. Active ingredients detected in sloths samples were ametryn, chlorothalonil, chlorpyrifos, diazinon, difenoconazole, ethoprophos and thiabendazole. These active ingredients were used in intensive agricultural production for bananas, pineapples and other crops. Blood plasma cholinesterase activity (PChE) was determined by the Ellman method modified for micro plates. Enzyme activity determination was normalized to protein content in the samples according to Bradford method. Wild sloth PChE activity was similar for both species while sloths in captivity showed differences between species. Enzyme activity was significantly lower for two-toed sloths. This study showed that sloths were exposed to pesticides that caused acute and chronic effect in mammals and can also be a threat to other wildlife species. There is a need to better understand the potential effects of exposure to pesticides in sloths and other wild mammal populations, especially those threatened or endangered. More studies in this field must be carried out on the wildlife fauna inhabiting the agricultural landscape and its surroundings.

Environmental hazards associated with pesticide import into Costa Rica, 1977-2009.

Raw pesticide import data from 1977 to 2009 obtained from the Ministry of Agriculture in Costa Rica were processed and analyzed. The quantity of specific active ingredients (a.i.), and chemical groups were calculated by year and presented in ten-year periods. Three sets of environmental hazard indicators were constructed: one for general pesticides exposure to monitor tendencies in time, including total quantities imported divided by significant denominators, such as hectares of protected and wetland areas. The second indicator calculates pesticide use on the Pacific or Caribbean slope. The third one is an assessment of environmental hazards intended to estimate fate and toxicity to aquatic biota. A review of Costa Rican aquatic ecosystems' contamination with pesticides is presented. The annual average import as well as the quantity of pesticides capable of reaching water bodies increased during the analyzed period. The same was observed for harmful a.i., 98% of the pesticides imported were classified as acutely toxic for fish and crustaceans and 73% for amphibians. Approximately 8.4 kg of a.i. were imported per hectare of protected areas and 24.3 kg of a.i. per hectare of wetlands. The contamination of aquatic systems over time by specific pesticides matches quite well the list of imported ones. We recommend using data of pesticide imports as a source of information to evaluate environmental risk exposure and promote changes to reduce impacts on aquatic systems.

Hazard prioritization and risk characterization of antibiotics in an irrigated Costa Rican region used for intensive crop, livestock and aquaculture farming.

Antibiotics alter the homeostasis of microbial communities and select for antibiotic-resistant bacteria in the wild. Thus, the accumulation of unnaturally high concentration of these substances in the environment due to their use in human activities can be regarded as a neglected form of pollution, especially in countries with agricultural-based economies. Qualitative and quantitative information on antibiotic usage in Costa Rica is scarce, hence the design and enforcement of prevention strategies and corrective measures is difficult. To address this issue, and aiming in the long run to contribute with a more rational use of pharmaceuticals in the tropics, we characterized the hazard associated with the antibiotics used during 2008 in agriculture, aquaculture, pig farming, veterinary medicine and human medicine in the major irrigation district of Costa Rica. Hazard indicators were calculated based on antibiotic use and a weighted algorithm that also considered antibiotic fate, toxicity, and resistance. Moreover, hazard quotients were computed using maximum environmental concentrations reported for Costa Rican surface waters and predicted no effect concentrations for aquatic organisms. The number of antibiotics used in the ATID during the study were n = 38 from 15 families. Antibiotic consumption was estimated at 1169-109908 g ha(-1) year(-1) and, distinctively, almost half of this figure was traced back to phenicols. Tetracyclines, with a particular contribution of oxytetracycline, were the most widely used antibiotics in agriculture and veterinary medicine. Oxytetracycline, florfenicol, chlortetracycline, sulfamethoxazole, erythromycin, ciprofloxacin, enrofloxacin, sulfamethazine, trimethoprim and tylosin, in that order showed the highest hazard indicators. Moreover, hazard quotients greater than 1 were calculated for oxacillin, doxycycline, oxytetracycline, sulfamethazine, and ciprofloxacin. Studies dealing with the ecotoxicology of tetracyclines, sulfonamides and quinolones, as well as surveys of phenicol resistance among environmental bacteria, should be prioritized in Costa Rica.

Monitoring pesticide use and associated health hazards in Central America.

We established methods for monitoring pesticide use and associated health hazards in Central America. With import data from Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama for 2000-2004, we constructed quantitative indicators (kg active ingredient) for general pesticide use, associated health hazards, and compliance with international regulations. Central America imported 33 million kg active ingredient per year. Imports increased 33% during 2000-2004. Of 403 pesticides, 13 comprised 77% of the total pesticides imported. High volumes of hazardous pesticides are used; 22% highly/extremely acutely toxic, 33% moderately/severely irritant or sensitizing, and 30% had multiple chronic toxicities. Of the 41 pesticides included in the Stockholm Convention on Persistent Organic Pollutants (POPs), the Rotterdam Convention on Prior Informed Consent (PIC), the Montreal Protocol on Substances that Deplete the Ozone Layer, the Pesticide Action Network (PAN) Dirty Dozen, and the Central American Dirty Dozen, 16 (17% total volume) were imported, four being among the 13 most imported pesticides. Costa Rica is by far the biggest consumer. Pesticide import data are good indicators of use trends and an informative source to monitor hazards and, potentially, the effectiveness of interventions.