Polluted water from an urban reservoir (Madín dam, México) induces toxicity and oxidative stress in Cyprinus carpio embryos.

The Madín Dam is a reservoir located in the municipalities of Naucalpan and Atizapán, in the metropolitan area adjacent to Mexico City. The reservoir supplies drinking water to nearby communities and provides an area for various recreational activities, including kayaking, sailing and carp fishing. Over time, the number of specimens of common carp has notably diminished in the reservoir, which receives direct domestic drainage from two towns as well as numerous neighborhoods along the Tlalnepantla River. Diverse studies have demonstrated that the pollutants in the water of the reservoir produce oxidative stress, genotoxicity and cytotoxicity in juvenile Cyprinus carpio, possibly explaining the reduction in the population of this species; however, it is necessary to assess whether these effects may also be occurring directly in the embryos. Hence, surface water samples were taken at five sites and pharmaceutical drugs, personal care products (especially sunscreens), organophosphate and organochlorine pesticides, and other persistent organic pollutants (e.g., polychlorinated biphenyls and polycyclic aromatic hydrocarbons) were identified. Embryos of C. carpio were exposed to the water samples to evaluate embryolethality, modifications in embryonic development, lipoperoxidation, the quantity of hydroperoxide and oxidized proteins, and antioxidant enzyme activity (superoxide dismutase, catalase and glutathione peroxidase). It was found that the polluted water of the Madín Dam gave rise to embryolethality, embryotoxicity, congenital abnormalities, and oxidative stress on the common carp embryos.

DNA damage and cytotoxicity induced on common carp by pollutants in water from an urban reservoir. Madín reservoir, a case study.

Madín Reservoir provides a substantial amount of drinking water to two municipalities close to Mexico City metropolitan area. However, it receives untreated wastewater discharges from domestic sources in the towns of Nuevo Madín and others, as well as diverse pollutants which are hauled by the Río Tlalnepantla from its upper reaches, so that the xenobiotics in the reservoir are highly diverse in terms of type and quantity. Previous studies showed that MR is contaminated with xenobiotics such as Al, Hg and Fe, as well as NSAIDs, at concentrations exceeding the limits established for aquatic life protection. These pollutants have been shown to induce oxidative stress on Cyprinus carpio and may therefore also damage the genetic material of exposed organisms, eliciting cytotoxicity as well. The present study aimed to determine the genotoxicity and cytotoxicity induced on blood, liver and gill of C. carpio by the pollutants present in MR water. Specimens were exposed to water from five sampling sites and the following biomarkers were evaluated: DNA damage by comet assay, frequency of micronuclei, apoptosis by TUNEL assay and caspase-3 activity. Significant increases relative to the control group (P < 0.05) were found with all biomarkers in all tissues evaluated, with the level of damage differing between sampling sites. In conclusion, pollutants present in MR water are genotoxic and cytotoxic to C. carpio, and this sentinel species, coupled with the biomarkers evaluated herein, is a reliable tool for assessing the health risk to wildlife posed by exposure to pollutants in freshwater bodies.

Removal of methyl parathion in water, by Dugesia dorotocephala.

The aim of this study was to determine the efficiency of Dugesia dorotocephala on Methyl parathion removal. An initial concentration of 1.25 microg mL(-1) of MeP was used to evaluate the removal capacity of planarian. A first-order removal kinetics was obtained with a disappearance rate constant (k(r)) of 0.49 days(-1) and 69% efficiency on contaminant removal. This is significantly different (p < 0.5) from the degradation occurring in control systems, leading us to conclude that D. dorotocephala effectively removes MeP from contaminated water.

[The prescription of drugs in a dental clinic of a Mexican university hospital]. / Prescripción de medicamentos en una clínica odontológica de una universidad mexicana.

OBJECTIVE: To assess the drug prescription service in a dental clinic of a Mexican university hospital. METHOD: An observational, descriptive study was carried out which analysed 698 drugs prescribed for dental problems in 14 dental health care departments in our clinic between the period of January-June 2005. The following criteria were established: prescribed drug, indication, dosage, dosage interval, individualised treatment, treatment duration and potential drug interactions. Information taken from prescriptions and clinical records was compared with information from literature on the subject in order to determine the adequacy of prescription criteria. RESULTS: The most frequently prescribed drugs were paracetamol, naproxen, ampicillin and dicloxacillin (43.26, 15.38, 7.45 and 7.02%). The prescription criteria which showed the least adequacy were as follows: indication, dosage and dosage interval. The main potential drug interactions occurred between non-steroidal anti-inflammatory drugs and captopril/amoxicillin. CONCLUSIONS: Taking the above into consideration, it was determined that 37.25% of prescriptions were inadequate. This study has helped to establish strategies which will facilitate the appropriate use of drugs in the future.

Methyl parathion toxicity to and removal efficiency by Typha latifolia in water and artificial sediments.

Methyl parathion (MeP) is a very hazardous pesticide freely used in agriculture in Mexico. This pesticide and others, arriving through different processes, exert significant effects on water quality with serious consequences for environmental and human health. This study evaluates the removal efficiency of common cattail Typha latifolia L. on MeP in water and artificial sediments. The effects of the pesticide on this macrophyte after 10 days of exposure were determined using a concentration range of 0-200 mg l(-1), 198.1+/-1.79 g average biomass, pH 7.0, 18-22 degrees C temperature and natural daylight/darkness periods, using chlorophyll production as a biomarker. Removal kinetics were conducted under similar conditions on days 0, 3, 7, 9, 11 and 14 of exposure, using 6 mg l(-1) in each system. Pesticide concentration, chlorophyll content and glutathione S-transferase (GST) activity were quantified. Results show a high removal efficiency of cattails on MeP in water and sediments relative to controls. An increase in GST activity and a decline in chlorophyll content in the test systems were not significantly different relative to controls. Cattails may thus be a good candidate for development of a phytoremediation system for MeP-contaminated water and artificial sediments.

Hemoglobin concentration and acetylcholinesterase activity of oligochaetes in relation to lead concentration in spiked sediments from Ignacio Ramirez reservoir.

This paper presents toxicity and uptake data of Limnodrilus hoffmeisteri generated by lead in systems using natural sediments from Ignacio Ramírez reservoir. Lead uptake, hemoglobin concentration, and acetylcholinesterase activity were studied in L. hoffmeisteri exposed to spiked sediments. All assays of lead uptake were conducted using whole sediments. Sediment texture was also considered. Acetylcholinesterase activity and hemoglobin concentration decreased after treatment with lead. Acetylcholinesterase activity and hemoglobin concentration tests indicated a response to the concentration of lead. These results suggest the usefulness of a diversity of bioassays to evaluate the toxicity of sediments polluted with heavy metals.

Toxic effects of zinc from trout farm sediments on ATP, protein, and hemoglobin concentrations of Limnodrilus hoffmeisteri.

Zinc (Zn) is a nutritionally essential metal, and deficiency results in severe health consequences to aquatic organisms. In this study toxicity data for Limnodrilus hoffmeisteri produced by Zn in systems using three natural sediments (trout farms: El Oyamel, El Truchón, and El Potrero) are presented. Hemoglobin, adenosine triphosphate (ATP), and protein concentrations were measured in L. hoffmeisteri exposed to spiked sediments, as indicators of exposure. Physicochemical characteristics of water and sediments were also considered. Zn concentrations were measured in water and sediment. El Oyamel, El Truchón, and El Potrero pond sediments did not have similar physicochemical characteristics. Zn concentrations of water obtained from the rustic ponds were near 0.4575 mg/L; however, this metal was always found to be higher in the sediments (0.0271-0.9754 mg/kg). The bioassay with worms demonstrated that pond sediments from El Oyamel, El Potrero, and El Truchón produced toxicity since ATP and protein concentrations were low compared to controls (organisms without metal). All spiked sediments had a significant reduction effect on ATP, protein, and hemoglobin concentrations. This investigation clearly shows that sediments of El Truchón, El Oyamel, and El Potrero possess toxicity potential. These results suggest the usefulness of these bioassays to evaluate the toxicity of sediments polluted with heavy metals.

[Toxic effect of DDT, chlordane and water from the Ignacio Ramírez dam (Mexico), on Daphnia magna (Crustacea: Daphnidae)]. / Efecto tóxico del DDT, clordano y agua de la presa Ignacio Ramírez (México), sobre Daphnia magna (Crustacea: Daphnidae).

Chlorodiphenylnitrichloroethane (DDT) and chlordane (CLO) are currently used in Mexico to control malaria and termites. From 1990 to 1996 a total of 27 ton of DDT and 508 of CLO were imported. We establish a methodology to determine their environmental impact in a Mexican dam (Ignacio Ramírez). The toxic effect of DDT and CLO were evaluated on the o-demethylase (OD) and acethycholinesterase activities (AchA) of the cladoceran Daphnia magna exposed to different concentrations of the insecticides solved in water from three sites. Their effect on the AchA and OD activities, and so the CL50 were used as exposure bioindicators to determine the more polluted sites. The physicochemical characteristics of water and the biodiversity of the dam test sites were considered. The station near the floodgate has toxicity potential because enzymatic activities were modified. We suggest the use of AchA and OD activities measure in the cladoceran to evaluate the toxicity of a water body polluted by organochlorate insecticides.