Determination of Bioavailable Aluminum in Natural Waters in the Presence of Suspended Solids.

Analyses of natural waters frequently show elevated levels of total aluminum (Al) attributable to acid extraction of Al from the total suspended solids (TSS) minerals. Hence, there is a need for an analytical method that measures only bioavailable Al. Natural waters high in TSS were collected to study the chronic effects of Al on Ceriodaphnia dubia. In the collected waters TSS ranged from 30 to 411 mg/L; total Al concentrations ranged from 2.0 to 44.8 mg/L. The TSS in natural waters inhibited reproduction of C. dubia up to 40% in comparison to the same filtered waters. This inhibition did not correlate with the concentration of TSS or total Al; it was attributed to nutritional deficiency and was prevented by increasing the food supply. To demonstrate that toxicity can be measured in natural waters, samples with elevated TSS were spiked with soluble Al, and survival and reproduction were measured in chronic studies performed at pH 6.3 and 8.0. To properly characterize the Al concentrations in the toxicity studies, a method was needed that could discriminate bioavailable Al from mineral forms of Al. An extraction method at pH 4 for bioavailable Al was developed and evaluated using C. dubia chronic toxicity studies in the presence of TSS. It is concluded that the proposed method is better able to discriminate chronic toxicity effects attributable to bioavailable Al from mineralized nontoxic forms of Al compared with existing methods using total or total recoverable Al (i.e., extraction at pH ≤ 1.5). We propose that this new method be used when assessing the potential for Al in natural surface waters to cause toxicity. Environ Toxicol Chem 2019;38:1668-1681. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Effect of Fe (III) on Pseudokirchneriella subcapitata at circumneutral pH in standard laboratory tests is explained by nutrient sequestration.

The complex chemistry of iron (Fe) at circumneutral pH in oxygenated waters and the poor correlation between ecotoxicity results in laboratory and natural waters have led to regulatory approaches for iron based on field studies (US Environmental Protection Agency Water Quality Criteria and European Union Water Framework Directive proposal for Fe). The results of the present study account for the observed differences between laboratory and field observations for Fe toxicity to algae (Pseudokirchneriella subcapitata). Results from standard 72-h assays with Fe at pH 6.3 and pH 8 resulted in similar toxicity values measured as algal biomass, with 50% effect concentrations (EC50) of 3.28 mg/L and 4.95 mg/L total Fe(III), respectively. At the end of the 72-h exposure, however, dissolved Fe concentrations were lower than 30 µg/L for all test concentrations, making a direct toxic effect of dissolved iron on algae unlikely. Analysis of nutrient concentrations in the artificial test media detected phosphorus depletion in a dose-dependent manner that correlated well with algal toxicity. Subsequent experiments adding excess phosphorus after Fe precipitation eliminated the toxicity. These results strongly suggest that observed Fe(III) toxicity on algae in laboratory conditions is a secondary effect of phosphorous depletion. Environ Toxicol Chem 2017;36:952-958. © 2016 SETAC.

Migration protocol to estimate metal exposure from mouthing copper and tin alloy objects.

BACKGROUND: Low blood lead levels previously thought to pose no health risks may have an adverse impact on the cognitive development of children. This concern has given rise to new regulatory restrictions upon lead metal containing products intended for child use. However few reliable experimental testing methods to estimate exposure levels from these materials are available. METHODS: The present work describes a migration test using a mimetic saliva fluid to estimate the chronic exposure of children to metals such as lead while mouthing metallic objects. The surrogate saliva medium was composed of: 150 mM NaCl, 0.16% porcine Mucin and 5 mM buffer MOPS, adjusted to pH 7.2. Alloys samples, in the form of polished metallic disc of known surface area, were subjected to an eight hours test. RESULTS: Two whitemetal alloys Sn/Pb/Sb/Cu and three brass alloys Cu/Zn/Pb were tested using the saliva migration protocol. In the case of the whitemetal alloys, first order release kinetics resulting in the release of 0.03 and 0.51 µg lead/cm2 after 8 hours of tests were observed, for lead contents of 0.05-0.07% and 5.5%, respectively. Brasses exhibited linear incremental release rates of 0.043, 0.175 and 0.243 µg lead/cm2h for lead contents of 0.1-0.2%, 1.7-2.2% and 3.1-3.5%, respectively. The linear regression analysis of lead release rates relative to Pb content in brasses yielded a slope of 0.08 µg lead/cm2h%Pb (r2 = 0.92). Lead release rates were used to estimate the mean daily mouthing exposure of a child to lead, according to age-specific estimates of mouthing time behavior. Calculated daily intakes were used as oral inputs for the IEUBK toxicokinetic model, predicting only marginal changes in blood lead levels (0.2 µg lead/dL or less) for children aged 0.5 to 1 years old exposed to either class of alloy. CONCLUSIONS: The results of this study as a whole support the use of migration data of metal ions, rather than total metal content, to estimate health risk from exposure to metals and metal alloys substances in children.

Application of an acute biotic ligand model to predict chronic copper toxicity to Daphnia magna in natural waters of Chile and reconstituted synthetic waters.

The objective of the present study was to assess the predictive capacity of the acute Cu biotic ligand model (BLM) as applied to chronic Cu toxicity to Daphnia magna in freshwaters from Chile and synthetic laboratory-prepared waters. Samples from 20 freshwater bodies were taken, chemically characterized, and used in the acute Cu BLM to predict the 21-d chronic Cu toxicity for D. magna. The half-maximal effective concentration (EC50) values, determined using the Organisation for Economic Co-operation and Development (OECD) 21-d reproduction test (OECD Method 211), were compared with the BLM simulated EC50 values. The same EC50 comparison was performed with the results of 19 chronic tests in synthetic media, with a wide range of hardness and alkalinity and a fixed 2 mg/L dissolved organic carbon (DOC) concentration. The acute BLM was modified only by adjustment of the accumulation associated with 50% of an effect value (EA50). The modified BLM model was able to predict, within a factor of two, 95% of the 21-d EC50 and 89% of the 21-d half-maximal lethal concentrations (LC50) in natural waters, and 100% of the 21-d EC50 and 21-d LC50 in synthetic waters. The regulatory implications of using a slightly modified version of an acute BLM to predict chronic effects are discussed.

Biotic ligand model prediction of copper toxicity to daphnids in a range of natural waters in Chile.

The objective of this study was to assess the predictive capacity of the biotic ligand model (BLM) for acute copper toxicity to daphnids as applied to a number of freshwaters from Chile and to synthetic laboratory-prepared waters. Thirty-seven freshwater bodies were sampled, chemically characterized, and used to determine the copper concentration associated with the 50% of mortality (LC50) for Daphnia magna, Daphnia pulex, and Daphnia obtusa (native to Chile). The data were then used to run three versions of the acute copper BLM, and the predicted LC50s were compared to the observed ones. The same was done with synthetic assay media at various hardness and dissolved organic carbon (DOC) levels. The BLM versions differed in the affinity constants for some biotic ligand-ion pairs, stability constants for inorganic Cu complexes, and assumptions regarding Cu binding to DOC. All three versions showed a high degree of predictive performance, mostly within a twofold range of observed toxicity values. The D. obtusa data set was used to compare water quality criteria (WQC) derived from the observed toxicity values with those derived from either the BLM or the U.S. Environmental Protection Agency (U.S. EPA) procedure. For most low DOC waters, the three procedures generated similar WQCs. For the high-DOC waters, the EPA-derived criteria were significantly lower, that is, greatly overprotective. The results are also discussed in terms of the validation of the BLM for regulatory use.

Grado de Desarrollo Organizacional de los Distritos de Salud / sss

El presente documento tiene el objetivo de identificar el desarrollo organizacional alcanzando por los distritos de salud en el marco de la política de salud y la organización del sistema regionalizado, descentralizado e integrado de salud. Conocer el avance y desarrollo de los distintos ambitos del desarrollo organizativo de los distritos de salud.

"Supervición y evaluación del distrito VI Sacaba" Cochabamba-Bolivia / \"Supervision and evaluation of the district VI took out\" Cochabamaa Bolivia

El presente trabajo contiene la evaluación y supervisión de los recursos humanos del distrito de Sacaba, del hospital de área, de los puestos médicos, de la actividad educativa

Propuesta teórica, metodológica y operativa del proceso de educación permanente de los distritos / sss

El presente documento, la Educación Permanente, concebida como un proceso para cualificar al personal de salud y coadyuvar a elevar el nivel de salud de la población, debe ser considerada como un componente fundamental del proceso de desarrollo de los servicios de salud

Sobre un caso de aspergillosis pulmonar

Paciente con antecedentes de enfermedad tuberculosa bilateral cavitariade predominio izquierdo que realiza tratamiento médico con tuberuclosis de preimera y segunda línea en los años 1974 a 1979. Se consideran imágenes residuales, dos imágenes cavitarias localizadas en los segmentos apicales de ambos lóbulos superiores. A partir de octubre de 1977 se inicia sintomatología de hemoptisis y espectoración hemoptoica en repetidas oportunidades. El 9 de noviembre de 1977 se diagnostica aspergillosis, razón por la que es intervenida quirurgicamente en fecha 10 de enero de 1980 de neumoneotomía, comprobándose histopatológicamente el diagnóstico pre-operatorio. Durante estos tres años el estado bronco-pulmonaar es satisfaactorio y se considera que se consiguió éxito con el tratamiento médico quirúrgico.