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J C Sanchez-Hernandez

Publications and source records attributed to J C Sanchez-Hernandez.

5 recordsLinked to original sources
PubMed2006

Earthworm biomarkers in ecological risk assessment.

Earthworms have had a notable contribution in terrestrial ecotoxicology. They have been broadly used to assess environmental impact from metal pollution, and they are typical test organisms (e.g., Eisenia) in standardized toxicity tests. Several reviews and international workshops have stressed the need for increasing the understanding and applicability of earthworm biomarkers in the ecological risk assessment (ERA) process. This review summarizes recent available information concerning the most investigated earthworm biomarkers. In earthworms, the use of biomarkers has been focused on assessing metal pollution, and available data on biomarker responses to organic contaminants are rather limited. The potential for applying earthworm biomarkers in the standardized toxicity tests is suggested in view of their significant contribution to the risk assessment of contaminated soils (e.g., estimation of bioavailable and bioactive fraction or sublethal effects). Field studies involving earthworm biomarkers are still scarce and are summarized according to their main practical approaches in retrospective ERA: biological surveys, laboratory tests of the soil, simulated field studies, and in situ exposure bioassays. Despite the great volume of laboratory studies on earthworm biomarkers, future lines of research are suggested besides the recommendations made by others: (1) the potential and limitations of the inclusion of biomarkers in the standardized toxicity tests should be examined under a well-defined weight-of-evidence framework; (2) it is necessary to develop operating guidelines to standardize earthworm biomarker assays, an important step to apply biomarkers in a regulatory context; (3) molecular and physiological biomarkers should be directly linked to behavioral changes with significant ecological implications, an important step in considering them as ecotoxicological biomarkers; and (4) biomarkers to organic pollutants of current concern (e.g., polycyclic aromatic hydrocarbons, anti-ChE and pyrethroid insecticides, polybrominated flame retardants, etc.) need to be developed and validated in the field. Also, an increase in the knowledge of earthworm biomarkers is undoubtedly useful in assessing the effectiveness of procedures for recovering/protecting the environment (e.g., phytoremediation or agrienvironment schemes) besides its potential use in the ERA framework.

Animals↗
PubMed2001

Bioavailability of PAHs in the Biobio river (Chile): MFO activity and biliary fluorescence in juvenile Oncorhynchus mykiss.

Cytochrome P450-dependent monooxygenase (MFO) activity and levels of bile PAH metabolites were measured in fish (Oncorhynchus mykiss) exposed to Biobio river (Chile) water. Experiments were performed simultaneously in both the field and laboratory to investigate whether the river water contained notable bioavailable PAH fractions. The field experiment was conducted using fish caged for 41 days at La Mochita (Biobio river mouth) whereas the laboratory experiment involved a 21-day exposure treatment with water collected in the same area. Induction of hepatic MFO, assayed by benzo(a)pyrene monooxygenase activity (BaPMO), and levels of PAH metabolites in the bile were measured in groups of eight (field experiment) and four specimens (laboratory experiment) sampled after 5, 10, 21 and 41 days of exposure. BaPMO was induced by a factor of 23 and 25 in fish caged for 21 and 41 days, respectively. Likewise, a significant BaPMO induction was found in the fish group experimentally exposed to river water for 21 days. Biliary fluorescence measurements, recorded by fixed wavelength fluorescence (FF) and synchronous fluorescence spectroscopy (SFS), revealed significantly high levels of PAH metabolites in bile samples of fish caged for 21 and 41 days. A positive relationship was found between BaPMO activity and biliary PAH metabolites. This study provides evidences that (i) Biobio river water contains a significant bioavailable PAH fraction in terms of marked effects on fish and (ii) the biological indicators MFO activity and bile PAH metabolites represent an excellent screening methodology to assess PAH exposure.

Animals↗
PubMed2000

Biomarker responses at different levels of biological organisation in crabs (Carcinus aestuarii) experimentally exposed to benzo(alpha)pyrene.

The aim of this study was to validate a multi-trial biomarker approach for the evaluation of toxicological risk due to benzo(alpha)pyrene. Carcinus aestuarii, exposed to increasing concentrations of B(alpha)P in the water, was used as the bioindicator organism. A set of biomarkers were tested in order to: identify biological materials for biomarker and residue analysis; determine a group of sensitive techniques for the assessment of PAH contamination; investigate correlation between responses at different levels of biological organisation. The results underlined that BPMO activities in hepatopancreas and gills were a good biomarker of exposure to PAH-type compounds. B esterases activities in hemolymph and porphyrin patterns in excreta could be proposed as a non-destructive approach for evaluating chemical exposure in this species.

Animals↗
PubMed2000

Trace element contamination in Antarctic ecosystems.

Data concerning trace element concentrations in both abiotic and biotic components of the Antarctic ecosystems are summarized here to be used as a first background database for pollution detection. Antarctic ancient ice and snow cores have been used to assess past and present-day changes in global atmospheric levels of certain trace elements. Concentrations of Pb, Cd, and Hg in the Antarctic tropospheric cell have varied according to glacial and interglacial periods before humans began to contaminate the atmosphere with these metals. Based on data of Pb concentrations in the Antarctic ancient ice cores and samples of recent snow, most of the Pb in Antarctica is anthropogenic. Moreover, this metal has decreased in recent years as a consequence of the reduced use of leaded gasoline in countries of the Southern Hemisphere. Reliable experimental and field data have indicated, however, that human activity in Antarctica contributes significantly to increasing atmospheric Pb levels in this continent, whereas the environmental impact of other metals such as Cd, Zn, or Hg is restricted to the area a few hundreds of meters about the anthropogenic source. Trace element concentrations in Antarctic abiotic matrixes are generally at ultratrace levels, challenging analytical detection limits and increasing the risk of unwanted contamination. Pb and Hg concentrations in Antarctic snow, surficial soil, air, and marine sediment have been considered as the lowest concentrations ever reported. Conversely, concentrations in Antarctic biota, are comparable to those from polar and temperate areas of the Northern Hemisphere, in particular Cd and Hg. Environmental and biological factors favoring a greater metal accumulation by Antarctic biota are discussed. Growth rate of the organisms and detoxification mechanisms (e.g., metallothioneins, molting cycles) are largely affected by the extreme environmental conditions in Antarctica (water supply, temperature regimen, light availability) that probably interfere with uptake, storage, and excretion of trace elements by organisms. On the other hand, environmental factors such as the upwelling of Cd-rich waters and local volcanism undoubtedly increase the bioavailability of metals in the Antarctic environment. In this context, several Antarctic organisms such as fish, mollusks, lichens, and mosses have been proposed as suitable biomonitors, and their trace element concentrations have been suggested as baselines. Structure and dynamics of Antarctic ecosystems as well as quantifying metal point sources and long-range atmospheric transport require in-depth studies to improve the assessment of human impact in Antarctica.

Animals↗