Carlos E. Rodríguez-Rodríguez

An environmental risk assessment of pharmaceuticals was conducted in surface waters from a tropical agricultural region in Costa Rica to describe their potential effects in rural ecosystems. The study collected 58 surface water samples from 22 sampling points in an intensive pineapple cultivation area in the Northern Region of the country and analyzed pharmaceuticals using a multiresidue method by Ultra-High Performance Liquid Chromatography (UHPLC) coupled to a triple quadrupole mass spectrometer. Environmental risks were assessed using chronic (Hazard Quotient, HQ), acute (Toxic Units, TU), and antibiotic resistance selection (HQ_Res) risk assessments. Monitoring revealed contamination with 15 different pharmaceuticals, including a predominance of antibiotics and caffeine, which showed the highest concentrations (max 17.5 µg/L). The risk assessment identified that 10 of the 15 detected pharmaceuticals posed a moderate to high chronic risk to aquatic life; specifically, sulfathiazole, clarithromycin, caffeine, and ofloxacin were categorized as high-risk compounds (HQ > 1). Furthermore, ciprofloxacin and clarithromycin posed a high risk for the selection of antimicrobial resistance. Although acute risk was seldom described, it was mainly driven by pharmaceutical mixtures, with clindamycin identified as a high-risk compound for fish in one sample. The findings emphasize the critical need for surveillance and targeted mitigation strategies to address emerging threats, particularly antibiotics, in tropical agricultural landscapes.

Pesticide use in intensive agricultural systems poses a growing concern for human and environmental health. In Costa Rica, large-scale pineapple cultivation involves frequent agrochemical applications, increasing the potential for contamination of groundwater and agricultural products. This study evaluated human health risks associated with pesticide residues detected in groundwater and pineapples from the Northern Region of Costa Rica, where intensive pineapple production takes place. Concentration data from ten groundwater sources and 30 pineapple samples collected between 2015 and 2018 were analyzed. Non-carcinogenic risk (estimated as a hazard quotient, HQ) and carcinogenic risk were determined for adults and children using U.S. EPA reference doses and cancer slope factors. Nine pesticides were detected in groundwater and nine in pineapples, with bromacil (up to 3.8 μg/L) being the most frequent compound in water and carbendazim (up to 0.027 mg/kg) in the fruit. All hazard quotients (HQ < 1) indicated no non-carcinogenic risk for either exposure route. Carcinogenic risks were only assessed for imazalil and diuron, with values for imazalil in groundwater ranging from 2.4 × 10⁻⁷ to 3.3 × 10⁻⁶, slightly exceeding the reference threshold (1 × 10⁻⁶) in children. Risk values from pineapple consumption were lower (≤ 10⁻⁷) compared to those from groundwater intake, suggesting minimal concern. Although overall risks remain low, the detection of residues in both water and fruit reveals multiple exposure pathways and highlights the need for cumulative risk assessments. Strengthening environmental monitoring and promoting integrated pesticide management are essential to safeguard public health in regions under intensive agricultural production.

Biopurification systems are designed for the treatment of pesticide-containing agricultural wastewater; their biologically active matrix, the biomixture, can be modified to enhance the pesticide removal capacity. Two approaches, fungal bioaugmentation with Trametes versicolor and amendment with biochar, were applied for the potential improvement of biomixtures’ capacity to remediate myclobutanil-contaminated wastewater. The conventional biomixture (B) and its modifications, either bioaugmented with Trametes versicolor (biomixture BT) or supplemented with pineapple biochar (5% v/v) (biomixture BB), were spiked with myclobutanil at a very high concentration (10,000 mg/kg) to simulate extreme on-farm events such as the disposal or leakage of commercial formulations. The dissipation followed a bi-phasic behavior in every case. Both modifications of the conventional biomixture increased the dissipation rates, resulting in estimated DT₅₀ values of 61.9 (BB) and >90 days (BT) compared to biomixture B (DT₅₀ = 474 days). The assessment of biomixtures’ detoxification was carried out with two different bioindicators: a seed germination test in Lactuca sativa and an algal growth inhibition test. Some degree of detoxification was achieved for all biomixtures in both indicators, with the exception of the biochar-containing biomixture, which, despite showing the fastest myclobutanil dissipation, was unable to maintain a steady detoxification trend towards the algae over the course of the treatment, probably due to biochar adverse effects. This approach seems promising for removing persistent myclobutanil from agricultural wastewater and demonstrates the dissipation capacity of biomixtures at extremely high pesticide concentrations likely to take place at an on-farm level.

This study evaluated the adsorption and desorption of imidacloprid (IMI), thiamethoxam (THM) and clothianidin (CLO) in an andisol (Freire soil) and an inceptisol (Chufquén soil) from southern Chile with different organic matter and clay contents. The soils had a slightly acidic pH and clay and clay-loam textures. The tests were carried out at 20 °C with CaCl₂ 0.01 M as the electrolyte. Kinetic experiments were performed and isotherms were fitted to the pseudo-second-order, Elovich, Weber–Morris, Freundlich and Langmuir models. The kinetics were best described by the pseudo-second-order model (R² > 0.99), indicating chemisorption; the rate was the highest for THM, although IMI and CLO achieved the highest retention capacities. The Chufquén samples, with lower organic matter but 52% clay, exhibited the highest K_f and q_m of up to 12.4 and 270 mg kg⁻¹, respectively, while the K_d (2.3–6.9 L kg⁻¹) and K_oc (24–167 L kg⁻¹) coefficients revealed a moderate leaching risk. THM was the most mobile compound due to its high solubility. Desorption was partially irreversible (H = 0.48–1.48), indicating persistence in soil. FTIR analysis confirmed the interaction with O-Al-O/O-O-Si-O groups without alterations in the mineral structure. In the soils examined in this study, the clay fraction and variable-charge minerals, rather than organic matter, were more closely associated with the adsorption behaviour of these NNIs.

The extensive use of pharmaceuticals has led to their occurrence in surface waters due to insufficient treatment processes for their removal. Their environmental impact remains largely unexplored for certain trophic levels, particularly plants and algae. Pharmaceuticals often occur in mixtures with other pollutants, highlighting the need for comprehensive toxicological assessments that evaluate their combined interactions. This study evaluated the acute toxicity of four high-hazard pharmaceuticals —diphenhydramine, fluoxetine, ketoprofen, and trimethoprim— and their binary mixtures, on the green microalgae Raphidocelis subcapitata and the aquatic macrophyte Lemna gibba. For individual compounds, R. subcapitata growth rate was inhibited in all cases, with fluoxetine, ketoprofen and diphenhydramine exhibiting moderate toxicity (EC₅₀ = 0.34, 0.14, and 4.88 mg/L, respectively), while trimethoprim showed low toxicity (EC₅₀ = 332.35 mg/L). Similar trends were observed in L. gibba, except for diphenhydramine, which also showed low toxicity (EC₅₀ = 26.57 mg/L). Binary mixtures demonstrated a synergistic interaction towards the microalgae in the presence of ketoprofen, except ketoprofen-trimethoprim combination (antagonism, p < 0.0001). In contrast, most interactions in L. gibba exhibited antagonism, except ketoprofen-fluoxetine (synergism, p = 0.0042). Differences were observed between the two model organisms for individual compounds and mixtures. No correlation was found between L. gibba experimental data and QSAR predictions derived from R. subcapitata. Our results highlight the need for: i. further studies including mixtures of relevant pharmaceuticals; ii. caution in the use of predictive models or extrapolation between taxa; and iii. the inclusion of fluoxetine and ketoprofen as priority compounds in future risk assessments.