Effects of diclofenac and salicylic acid exposure on Lemna minor: Is time a factor?

The global occurrence of pharmaceuticals in the aquatic environment has been considered a particularly concerning problem with unknown consequences. Non-steroidal anti-inflammatory drugs (NSAIDs) including diclofenac (DCF) and salicylic acid (SA), are among the most frequently prescribed drugs in the world, being consequently commonly found in the aquatic environment. Prolonged experiments (with duration of exposure that surpass those recommended by already established testing guidelines) are important to obtain ecologically relevant data to address the issue of NSAIDs ecotoxicity, because by being more realistically (namely in terms of levels and durations of exposure), such tests may indicate realistic challenges posed to aquatic organisms. Among the most common test species that are used for assessing environmental quality, plants play a leading role. Lemna species are among the most important plants used for ecotoxicity testing. Therefore, the aim of this study was to evaluate the temporal effect of a prolonged exposure of DCF and SA on Lemna minor. To attain this purpose, L. minor plants were chronically exposed to 0, 4, 20, and 100 µg/L of both pharmaceuticals, and samplings were performed at 6, 10 and 14 days of exposure. The analyzed endpoints were: levels of chlorophyll a, b and total, carotenoids; and enzymatic biomarkers, such as catalase, ascorbate peroxidase and glutathione-S-transferases. Diclofenac was responsible for alterations in all analyzed parameters in different intervals of exposure. Salicylic acid exposure was not capable of causing alterations on pigment contents of L. minor, however, enzymatic biomarkers were altered at all sampling intervals. Thus, it is possible to conclude that both pharmaceuticals can cause damage on the tested macrophyte species, biochemical parameters being more sensitive than physiological ones. Additional prolonged experiments are required to understand the chronic effects of different pharmaceuticals in the aquatic environment, especially in plants.

Nosocomial bloodstream infections in a nationwide study: comparison between solid organ transplant patients and the general population.

BACKGROUND: The incidence of bloodstream infection (BSI) varies according to the transplanted organ. Mortality can be as high as 24%, with a significant impact on graft survival. Transplantation is a risk factor for multidrug-resistant (MDR) organisms, but comparison with a non-transplanted population in a single large cohort has not been described. METHODS: This is a prospective nationwide study (16 centers) reporting data on 2364 monomicrobial nosocomial BSIs, comparing 83 episodes in solid organ transplant patients with 2447 BSIs occurring in the general hospital population. RESULTS: The prevalence of groups of infecting organisms (gram-positive, gram-negative, and fungi) was similar between transplant patients and the general population and a similar crude mortality rate was observed (34.9% in transplant vs. 43.3% in non-transplant patients). Staphylococcus aureus was the single most frequently isolated organism in both groups, and Acinetobacter species was more frequently isolated in the general population. Regarding MDR organisms, Klebsiella species, and Enterobacter species resistant to cefepime, as well as Acinetobacter species resistant to meropenem, were significantly more frequent in transplant patients. CONCLUSION: Antimicrobial resistance is higher, particularly among gram-negative bacteria in the transplant population, although the overall mortality rate between transplant and non-transplant patients with nosocomial BSI is similar.

Development of quantitative RNA biomarkers for detecting dioxin-like and estrogenic pollutants in Costa Rican native fish species.

Monitoring the environmental impact on native species is crucial for the correct management of tropical ecosystems. The Costa Rican fish Parachromis dovii (Cichlidae) and Poecilia gillii (Poecillidae) were used as sentinel species for freshwater bodies under considerable pressure by intensive agriculture Cichlidae development. Suitable qRT-PCR probes for the quantification of hepatic mRNA levels of two stress-related genes--vitellogen in (estrogenic effects) and cytochrome P4501A(CYP1A, dioxin-like compounds)--for both species were designed and validated in experimental treatments with model effectors (17beta-estradiol and beta-naphtoflavone, respectively), demonstrating their usefulness as markers of exposure to these two kinds of pollutants. Analysis of fish transplanted across pesticide contaminated sites near Palo Verde National Park, Pacific Coast of Costa Rica did show significant changes on hepatic Cyp1A in both species. In P. dovii, Cyp1A levels were enhanced in Barbubal and in the impacted Cabuyo sites in the rainy season whereas in P. gillii fish Cyp1A transcripts were down-regulated differently across rainy and dry seasons. Vitellogen in mRNA levels in P. gillii varied between males and females with males showing always low values which indicated no estrogenic effects. Within females, vitellogenin levels varied over 100,000 fold depending on their maturation stage, further demonstrating the ability of the method to monitor changes (natural or induced) in the reproductive system of the fish.

Pesticide residue analyses and biomarker responses of native Costa Rican fish of the Poeciliidae and Cichlidae families to assess environmental impacts of pesticides in Palo Verde National Park.

Pesticide chemical residues in water samples and biomarker responses in transplanted fish were used to monitor environmental hazards of pesticides in Palo Verde National Park (Costa Rica). The Costarican fish, Parachromis dovii (Ciclhidae) and Poecilia gillii (Poecillidae), were selected as sentinel species. Contaminant analyses detected up to 15 different pesticide residues in water with hexachlobenzene (2261 ng l(-1)), phorate (473 ng l(-1)), epoxiconazole (314) and bromacil (117 ng l(-1)) being the compounds found in higher concentrations. Biomarker responses evidenced impacts on cholinesterase activities in transplanted fish at Barbudal site probably due to the presence of organophosphate insecticides such as phorate. High enzyme activities of glutathione S-transferase and catalase and elevated levels of lipid peroxides were also observed at a site impacted by rice fields (Cabuyo); those effects could be associated with the presence of hexachloro benzene and triazole fungicides. In general, P. dovii biomarkers were affected to a greater extent than those of P. gillii in fish transplanted to sites associated with agriculture, which suggests the former species is a good candidate for future surveys.

Mechanisms of action of selective serotonin reuptake inhibitors in Daphnia magna.

Selective serotonin reuptake inhibitors (SSRI) are known to increase offspring production in Daphnia magna. This study tested the hypothesis that the increase of serotonin postsynaptic activity by SSRI changes the perception of the food environment and switches life-history responses toward higher food level: females reproduced earlier, producing more but smaller offspring. D. magna reproduction tests, respiration, feeding, and survival-starvation assays and studies of lipids, proteins, and carbohydrate levels of unexposed and exposed females to the SSRI fluoxetine and fluvoxamine and the 5-HT serotonin receptor antagonist cyproheptadine were conducted. Factorial life-history experiments and reproductive assays showed that exposure to SSRI increased juvenile development rate, clutch size, and decrease offspring size at low and intermediate levels of food rations. These effects were reversed by the presence of cyproheptadine, indicating that 5-HT function was essential to the SSRI effects on Daphnia and linking them to the pharmacological effects of SSRI in humans. Respirometry and survival assays and biochemical analyses of lipids, proteins and carbohydrate levels showed that exposure to SSRI increased oxygen consumption rates and decreased carbohydrate levels in adult females. These changes did not affect survival under starving conditions, but they significantly affected the capacity of the exposed animals to survive under anoxic conditions. These results suggest that SSRI increased aerobic catabolism in D. magna making exposed individuals apparently more able to exploit food resources under normoxic conditions, but at the cost of being more sensitive to low oxygen levels, a common situation in natural environments.

Evaluation of ketoprofen toxicity in two freshwater species: Effects on biochemical, physiological and population endpoints.

Among the most used non-steroidal anti-inflammatory drugs (NSAIDs), ketoprofen (KTF) assumes an important position. Nevertheless, its ecotoxicological effects in non-target organisms are poorly characterized, despite its use and frequency of occurrence in aquatic matrices. Thus, the aim of this study was to evaluate the possible toxicological effects of KTF contamination, in two freshwater species, Lemna minor and Daphnia magna, by measuring biochemical, physiological and population parameters. To attain this objective, both species were exposed to KTF at the same concentrations (0, 0.24, 1.2, 6 and 30 µg/L). L. minor plants were exposed during 4 d to these levels of KTF, and the enzymatic activity (catalase (CAT), glutathione S-transferases (GSTs) and carbonic anhydrase (CA)), and pigments content (chlorophylls a, b and total and carotenoids) were analyzed to evaluate the toxicity of this drug. D. magna was acutely and chronically exposed to KTF, and enzymatic activities (CAT, GSTs and cyclooxygenase (COX)), the feeding rates, and reproduction traits were assessed. In L.minor, KTF provoked alterations in all enzyme activities, however, it was not capable of causing any alteration in any pigment levels. On the other hand, KTF also provoked alterations in all enzymatic activities in D. magna, but did not affect feeding rates and life-history parameters. In conclusion, exposure to KTF, provoked biochemical alterations in both species. However, these alterations were not reflected into deleterious effects on physiological and populational traits of L. minor and D. magna.

Can salicylic acid modulate biochemical, physiological and population alterations in a macrophyte species under chemical stress by diclofenac?

Salicylic acid (SA) is a pharmaceutical drug that may exert toxic effects by its own; however, simultaneous exposure of plants to SA and to other substances, often results in the significant changes in the patterns of toxic response/resistance to these other sources of chemical stress. Thus, the aim of this work was to investigate the capacity of SA of modulating Lemna minor responses co-exposed to the pharmaceutical drug, diclofenac - DCF. To attain this objective, L. minor was exposed for 7 days, to DCF alone, and to combinations of DCF with SA. After exposure, biochemical, physiological and population endpoints were analyzed as follows: catalase (CAT) and glutathione S-transferases (GSTs) activities, pigments content (chlorophyll a (Chl a), b (Chl b) and total (TChl), carotenoids (Car) and [Chl a]/[Chl b] and [TChl]/[Car] ratios), and growth specific rate, fresh weight and root length. Single exposures to DCF were capable of causing effects in all analyzed endpoints. However, co-exposure of DCF with SA partially reverted these effects. Finally, we may suggest that SA is capable to prevent the toxicity of DCF in macrophytes, by modulating the toxic response of exposed plants.

Evaluation of pharmaceutical toxic effects of non-standard endpoints on the macrophyte species Lemna minor and Lemna gibba.

In the last years the environmental presence of pharmaceuticals has gained increasing attention. Research data show that these compounds can cause toxicological effects in different species of fish, mollusks and macroinvertebrates. However, the literature is scarce in terms of ecotoxicity data especially focusing on plants as test organisms. Ecotoxicological plant-based tests following the standard OEDC guideline 221 (OECD, 2006) are strongly restricted due to the recommended end-points: growth and yield of plants. It is necessary to develop and validate alternative macrophyte-based tests (non-standard endpoints), more sensible and providing additional information about the chemical contamination effects in plants. To attain this purpose, species from the Lemna genus were selected. Thus, the aim of this study was to analyze the toxic effects of pharmaceuticals in non-standard endpoints on two macrophyte species, Lemna minor and Lemna gibba. To this purpose an acute assay (96 h) was performed with L. minor and L. gibba exposed to chlorpromazine (CPZ), paracetamol (APAP), and diclofenac (DCF), in the following concentration ranges: 0 to 20 µg/L, 0 to 125 µg/L, and 0 to 100 µg/L, respectively. The analyzed endpoints were: levels of chlorophyll a and b, total chlorophyll, carotenoids, anthocyanins; chlorophyll fluorescence; and catalase activity. In general, higher concentrations of the tested pharmaceuticals caused significant effects on both Lemna species in terms of the different endpoints analyzed. In conclusion, acute exposures to CPZ, APAP, and DCF differently affected the defensive system of the tested species; among chlorophylls, chlorophyll b content was more affected, but pharmaceutical exposure was not able to cause alterations on chlorophyll fluorescence.

A Daphnia magna feeding bioassay as a cost effective and ecological relevant sublethal toxicity test for Environmental Risk Assessment of toxic effluents.

Environmental Risk Assessment of chemical products and effluents within EC countries require the use of cost effective standardized toxicity tests that in most cases are restricted to acute responses to high doses. Thus, subtle ecological effects are underestimated. Here we propose a short-term one day Daphnia magna feeding inhibition test as a cost effective and ecological relevant sublethal bioassay. The sensitivity and reliability of the proposed bioassay was tested in the laboratory against standardized bacteria, algae growth, D. magna and fish acute toxicity test by using 16 chemical mixture x water type combinations that included four different water types fortified with four complex chemical mixtures. Water types included ASTM hard water and three selected effluents diluted 1/10 in water to mimic worse field situations that many overexploited arid river ecosystems suffer during summer months when effluents are discharged into them with little dilution. The results obtained denoted a greater sensitivity of the proposed feeding bioassay in 51 out of 65 tests performed with an average sensitivity 50 fold greater than that of the standardized tests. The greater differences were obtained for mixtures that included narcotic chemicals and the lowest differences for those containing pesticides. Furthermore, feeding responses to the studied contaminant mixtures behaved differently to increasing TOC content than those based on bioluminescent bacteria and algae. Increasing TOC coming from sewage treated effluents decrease toxicity to the latter bioassays but increased those of D. magna feeding bioassays. These results empathize the need to include additional bioassays to monitor more accurately and realistically the toxicity of effluents or surface waters dominated by effluent discharges, a quite common situation in America and Mediterranean arid regions.

Trace metal concentration, antioxidant enzyme activities and susceptibility to oxidative stress in the tricoptera larvae Hydropsyche exocellata from the Llobregat river basin (NE Spain).

Caddisfly larvae of Hydropsyche exocellata were sampled from seven locations receiving increasing levels of urban and industrial waste water discharges along the Llobregat river system (NE Spain) during spring and summer 2003. Locations were selected to include aquatic communities in poor and good ecological state according to measured physicochemical water parameters and the analysis of benthic macroinvertebtrate communities. Whole body residues of selected metals (Fe, Al, Zn, Cu, Co, Ni, Pb, Cd) were determined in conjunction with antioxidant enzyme activities (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase activity of GST, GSTPX), a phase II enzyme (glutathione-S-transferase, GST) and lipid peroxide levels measured as thiobarbituric reactive species (TBARs) with the aim of investigating whether resident macroinvertebrate benthic species were responsive to changes in water quality. Caddisfly larvae inhabiting those rivers were exposed to increasing levels of metal pollution. Enhanced activities of two (CAT and GST) out of the four tested enzymes, coupled with increased levels of TBARs, indicated increasing levels of stress in the studied species towards downstream reaches or locations near industrial and urban areas. These results indicate that combination of chemical and biochemical responses can be used to assess and diagnose pollution in high stressed river ecosystems.

Phenotypic plasticity in Daphnia magna Straus: variable maturation instar as an adaptive response to predation pressure.

Life history responses of four Daphnia magna clones at two food levels were studied to assess the importance of maturation instar on the plasticity of fitness responses under simulated mortality regimes. Females of the clones studied could vary offspring size with consequent effects on their maturation time. Significant genetic variability in life history and fitness responses, measured as the intrinsic rate of population increase, within and across food levels was observed, but most of this variation could be attributed to maturation instar differences among clones within and across environments. In the laboratory, without extrinsic mortality, females maturing earlier always had higher fitness than those maturing later, indicating a clear fitness cost of delaying maturity. Nevertheless using a model, we showed that the observed maturation instar effects on life history responses can lead to differences in fitness under different size-selective predation regimes, such that females with delayed maturity have higher fitness under invertebrate predation while females maturing earlier have higher fitness under fish predation regimes. These results suggest that intraclonal variation in offspring size and hence in the number of maturation instars can be an adaptation to living in habitats subject to temporal fluctuations in fish and invertebrate predation pressure.

Abdominal ultrasound in acute schistosomiasis mansoni.

Reports on abdominal ultrasound studies in patients with acute schistosomiasis are still scarce and limited data are available on structural changes of the liver parenchyma in this stage of the disease. 26 patients with acute schistosomiasis mansoni were submitted to clinical and ultrasound examination. For ultrasound comparison, each acute patient was paired by age, gender, weight and height to a non-infected individual. Ultrasound showed a non-specific homogeneous size increase of the liver, and spleen in all acute patients, and easily identified intraabdominal lymph nodes in the periportal region in most cases. Three out of the five patients with periportal thickening underwent percutaneous liver biopsy. Periportal thickening disappeared 6 months after treatment for schistosomiasis. 24 months after successful treatment there was involution of the liver and spleen; lymph nodes, although reduced in size, were still easily recognized. Liver biopsy showed dense inflammatory infiltration of neutrophils, macrophages and eosinophils in the portal tracts associated with discrete fibrous tissue formation.

Influence of Schistosoma mansoni infection on the reproductive capacity of albino mice.

This paper reports reduction on the reproductive capacity of female mice infected with Schistosoma mansoni, either in the acute phase or in the chronic one of the disease. This decrease in the reproductive capacity was highly significant (93.3% and 86.7%, for the acute and chronic phases, respectively).

[Brain abscess caused by Nocardia sp in immunosuppressed patient]. / Abscesso cerebral por Nocardia sp em paciente imunossuprimido.

Patient with autoimmune haemolytic anaemia and thrombocytopenic purpura (Evans Syndrome), treated with immunosuppressive therapy (prednisone and azathioprine) developed brain abscess unresponsive to antimicrobial therapy, in spite of its 23 days duration. Diagnosis could be possible after recover secretion of peribulbar abscess and maintenance of this material over seven days in incubation.

Organic carbon content effects on bioavailability of pyrethroid insecticides and validation of solid phase extraction with Poly (2,6-diphenyl-p-phenylene oxide) Polymer by Daphnia magna toxicity tests.

Solid phase extraction with Poly (2,6-diphenyl-p-phenylene oxide) Polymer (Tenax) was used for determining the bioavailability of eleven pyrethroids in field collected sediments with different organic carbon content (OC). The bioavailable fraction of pyrethroids decreased with increasing OC in sediments; the percentages of desorption ranged from 10 to 20% for sediment with higher OC content (5.8%) and 15-40% for that with lower OC (2%). Generally pyrethroids showed low bioavailability and cyfluthrin resulted to be the most bioavailable among the studied pyrethroids. Acute toxicity tests with Daphnia magna were carried out on sediment spiked with three selected pyrethroids (λ-cyhalothrin, cypermethrin and deltamethrin) and served to validate the efficiency of Tenax as a method for assessing the bioavailability of pyrethroids. Toxicity test demonstrated that Tenax was able to remove the toxic bio-available fraction of pyrethroids in sediment. Extracts from Tenax beads after the desorption experiments and spiked sediment before desorption had an equivalent toxicity (LC50) to D. magna neonates at 48 and 72 h of exposure. These results indicate that Tenax beds can be used to predict bio-available and toxic fractions of pyrethroids sorbed to sediments to aquatic organisms like D. magna.

Enhanced offspring production in Daphnia magna clones exposed to serotonin reuptake inhibitors and 4-nonylphenol. Stage- and food-dependent effects.

Risk assessment of emerging pollutants requires the development of bioassays able to detect and understand novel mechanisms of action. This study tested the hypothesis that the increase of offspring production in Daphnia magna induced by certain pollutants may be mediated through different mechanisms, depending on development stages, clones and food rations The study included two selective serotonin reuptake inhibitors (SSRIs), fluoxetine and fluvoxamine, and the detergent metabolite 4-nonylphenol. Organisms were exposed from birth to adulthood or only during adulthood at low and high food ration levels. Results indicated that low exposure levels of the three studied substances increased offspring production and/or juvenile developmental rates similarly for all studied clones, but the responses differed among life-stages and food rations. When individuals were exposed to the studied chemicals from birth, enhanced offspring production per female was observed only at low and intermediate food rations. On the contrary, when exposures started in gravid females most treatments increased offspring production. Results obtained with SSRIs support previous findings, where it was stated that these compounds may amplify serotoninergic signaling in D. magna. Nonylphenol effects may be related to the reported alteration of this compound in Daphnia ecdysteroid metabolism. Further investigations are necessary to resolve the biochemical mechanism of SSRI and nonylphenol enhancing offspring production.

Environmental hazards of pesticides from pineapple crop production in the Río Jiménez watershed (Caribbean Coast, Costa Rica).

This study aimed to characterize environmental hazards of pesticides from pineapple production in riparian communities along the Jiménez River watershed. To achieve our objectives riparian ecological quality indices on riparian habitat and macroinvertebrate assemblages were combined with toxicity assays, fish biomarkers, physico-chemical water analysis and pesticide environmental hazards. During two consecutive years and two periods (July and October), three reference and four impacted sites were monitored. The ecological quality of benthic macroinvertebrates and of riparian habitats deteriorated from the reference sites downstream to the polluted reaches along the Jiménez River area affected by pineapple plantations. The toxicity of water to Daphnia magna also increased towards downstream reaches. Biomarkers of fish of the species Poecilia gillii and Bryconamericus scleroparius transplanted across the studied sites evidenced a clear anticholinergic effect towards downstream sites as well as increased levels of lipid peroxidation. Different pesticide residues were frequently detected in water samples collected across the Jiménez River watershed with herbicides (ametryn, bromacil, diuron), organophosphorus insecticides (diazinon and ethoprophos) and triazole fungicides being the greatest reaching levels above 1 µg L(-1) in downstream sites. Principal component and environmental hazard analysis of physico-chemical and biological responses established clear relationships among habitat deterioration and the ecological quality of macroinvertebrate communities, high levels of herbicides and poor plant growth, high levels of organophosphorus insecticides in water and anticholinesterase effects on fish, D. magna mortality and deterioration of macroinvertebrate communities. Fungicide and herbicide residue levels were also related with high levels of lipid peroxidation and high activities of glutathione S transferase in fish liver, respectively. These results indicated, thus, that riparian habitat deterioration due to deforestation and land use for agriculture and pesticide contamination are affecting river ecosystems.

Use of ractopamine during compensatory gain of finishing pigs on carcass and meat performance and quality / Uso de ractopamina durante ganho compensatório de suínos em terminação sobre o desempenho e a qualidade da carcaça e de carne

The objective of this study was to evaluate the effects of compensatory gain associated with the use of 10ppm ractopamine after a period of feed restriction in finishing pigs on performance, carcass and meat quality. Twenty castrated males and 20 females, at 110 days of age and 66.137±6.13kg live weight, were submitted to four treatments using a 2 x 2 factorial design (fed ad libitum or with 20% restriction between 0(21 days of age and fed with or without 10ppm ractopamine for 22(42 days of experimentation), with 10 replicates (animals). There was no interaction between the factors for any of the evaluated parameters. Animals treated with ractopamine presented better weight gain (1.083 versus 1.259kg), feed conversion (2.910 versus 2.577), warm and cold carcass weight (86.08 versus 89.00 and 83.46 versus 87.20kg, respectively), loin depth (63.02 versus 68.40mm), loin eye area (41.43 versus 46.59mm2) and muscle fiber diameter (27.48 versus 35.85µm). Animals submitted to feed restriction followed by ad libitum feed presented compensatory gain without losses to carcass and meat characteristics, but with a reduction in the ethereal extract (2.19 versus 1.64%) and lower water loss due to thawing in the meat (11.35 versus 9.42%). The effects of compensatory gain after food restriction and ractopamine are independent of the parameters evaluated.(AU)

Objetivou-se avaliar os efeitos do ganho compensatório associado ao uso de 10ppm de ractopamina após um período de restrição alimentar, em suínos em terminação, sobre características de desempenho, carcaça e qualidade de carne. Foram utilizados 20 machos castrados e 20 fêmeas, com 110 dias de idade e 66,137±6,13kg de peso vivo, submetidos a quatro tratamentos, fatorial 2 x 2 (alimentação à vontade ou com 20% de restrição entre zero e 21 dias de experimentação; e alimentação à vontade, sem ou com 10ppm de ractopamina, durante 22 a 42 dias de experimentação), com 10 repetições, sendo o animal a repetição. Não houve interação entre os fatores para nenhum dos parâmetros avaliados. Animais tratados com ractopamina apresentaram melhor ganho de peso (1,083 versus 1,259kg), conversão alimentar (2,910 versus 2,577), peso da carcaça quente e fria (86,08 versus 89,00 e 83,46 versus 87,20kg, respectivamente), profundidade do lombo (63,02 versus 68,40mm), área de olho de lombo (41,43 versus 46,59mm2) e diâmetro de fibras musculares (27,48 versus 35,85µm). Animais submetidos à restrição alimentar seguida de arraçoamento ad libitum apresentaram ganho compensatório sem prejuízos às características de carcaça e à carne, mas com redução do extrato etéreo (2,19 versus 1,64%) e menor perda de água por descongelamento na carne (11,35 versus 9,42%) Os efeitos do ganho compensatório após a restrição alimentar e da ractopamina mostram-se independentes sobre os parâmetros avaliados.(AU)

Blood biomarkers and contaminant levels in feathers and eggs to assess environmental hazards in heron nestlings from impacted sites in Ebro basin (NE Spain).

Blood biomarkers and levels of major pollutants in eggs and feathers were used to determine pollution effects in nestlings of the Purple Heron Ardea purpurea and the Little Egret Egretta garzetta, sampled on three Ebro River (NE Spain) areas: a reference site, a site affected by the effluents of a chlor-alkali industry and the river Delta. The two impacted heron populations showed mutually different pollutant and response patterns, suggesting different sources of contamination. In the population nesting near the chlor-alkali plant, elevated levels of hexachlorobenzene (HCB) and polychlorobiphenyls (PCBs) in eggs, and mercury in feathers in A. purpurea chicks were related with reduced blood antioxidant defenses and increased levels of micronuclei. In Ebro Delta, high levels of plasmatic lactate dehydrogenase in A. purpurea chicks and high frequency of micronuclei in blood of both species were tentatively associated with intensive agricultural activities taking place in the area. These results provide the first evidence of a biological response in heron chicks to the release of pollutants at a chlor-alkali plant.