Toxicología ambiental y analítica

Phorate an organophosphate insecticide is commonly applied on crops to kill the stem borers but major part of it reaches on the soil which is a pivotal component of the environment. The soil possesses diverse and numerous life forms amongst which earthworms are considered as major representative organisms. The level of toxicity of various pesticides is found different and is considered as one of the valuable parameters in killing the agricultural pests. In the present paper the acute toxicity (LC50) of phorate was evaluated for the epigeic earthworm, Eisenia fetida and assessed by artificial soil test method as per proposed in OECD testing guideline No. 207 (1984). Results showed that acute toxicity (LC50) of phorate was found to be 22.5 mg/kgat the end of 14 day artificial soil test, and is considered as ‘extremely toxic’ to the experimental worm. The purpose of the study was to ascertain its minimal dose to be applied to kill the pests but not the earthworms. These findings showed that a dose of less than its acute toxicity level may be applied on the crops that will not affect the earthworms.

Aquatic plant species and physico-chemicalparameters of Chemususu Dam, Baringo County, Kenya were studied from differernt sampling stationsD1, D2 and D3 situated in north west, south and north east directions of the dam respectively. There are only19 phytoplankton species (Nitzchiasp, Diatomavulgare, Synedrasp, Naviculasp, Oedogoniumsp, Spirogyra sp, Closteriumsp, Chodatellasp, Chlorella sp, Crucigeniasp, Pleurotaeniumsp, Gonatozygonsp, Closteriumaciculare, Pediastrumsp, Scenedesmussp, Cosmariumsp, Geminellasp, Ceratiumsp, Peridiniumsp). The common species present in all the sites were:Nitzchiasp, Scenedesmussp, Spirogyra sp, Chlorella sp, Ceratiumsp, Peridiniumsp, Gonatozygonsp, Synedrasp, and Navicula sp. In D1,Diatomavulgareand Cosmariumspin D2 were specific in these sites.Three emergent aquatic angiosperm species were present; Typhalatifoli aand Portulacaoleraceaare present at D1 site,while Aponogetona froviolaceus together with T.latifolia and P. oleraceaare at D2 site along the periphery of thiswater body. It is noticed that D3 sitetheseangiosperms are completely absent due to rocky habitat. Cynophytes arenot visible due to flow nutrient level and dam is also less than one year old. Theaveragevalues of chemical parameters (mg/l) are; nitrates 4.42±0.07, phosphates 4.23±1.17, sulphates 3.48±0.22, chloride 2.73±0.57, carbonates 8.6±0.7 and physical parameters such as conductivity 81.16μS/cm, dissolved oxygen is 4.2 mg/l,pH 6.77, turbidity 3.12 NTU and temperature is less than 21.5°C within the dam at an altitude of 2480 meters above the sea level. Based on currentphysico-chemical parameters and species composition, it is concluded that the water quality parameters of the dam meet the requirements for human consumption.

Toxicity and genotoxicity of one of the most widely spread species of aqueous plants of the Yenisei River – Elodea canadensis and bottom sediments of the Yenisei River containing 241Am have been evaluated for the first time. It is shown that the suspensions and extracts of plants or bottom sediments which do not contain 241Am, inherently decrease the survival of bacterial cells of specific strains as compared to the control samples. Cell death of E. coli in the aqueous plants accumulating 241Am was observed to be even higher, which is consistent with the toxicity of the control samples of aqueous solutions of 241Am salts. Non-radioactive suspensions of the control samples of the plants and bottom sediments also slightly influenced the survival of the S. typhimurium TA98 cells, whereas their survival abruptly decreased in the presence of 241Am. The samples of the bottom sediments without 241Am hardly influenced the «frequency of His reversions» of the indicator S. typhimurium. In the suspensions of the 241Am-containing bottom sediments a dose-dependent effect was observed both in the «frequency of reversions» and in the quantity of the detected His revertants in the S. typhimurium TA98 strain.

4-nonylphenol (4NP), a breakdown product of nonylphenol polyethoxylate, is a potent endocrine disruptor and persistent organic pollutant (POP). Due to physical and chemical properties, 4NP is capable of long range transport as both an aerosol and attached to dust particulates. Since nonylphenol polyethoxylates make up a substantial portion of many pesticides, agricultural regions are often sources of 4NP. Physical barriers such as mountain ranges may alter the distribution of this POP but does not stop the long range transport. The Central Valley of California, USA is an intensely farmed region adjacent to the Sierra Nevada Mountains subjected to onshore prevailing winds from the Pacific Ocean. Previous work revealed that the winter snow pack in the Sierra Nevada showed at least an order of magnitude more 4NP than surface water during summer months. As a result, spring melt water may send high concentrations of 4NP to organisms during critical developmental periods. Physical and geographical characteristics of snow and terrain were assessed to determine which factors affect 4NP accumulation in snow and regions at higher risk of 4NP exposure. Samples were taken from snow, surface water and atmospheric deposition for four consecutive years and analyzed by gas chromatography-mass spectroscopy for 4NP. Snow water and dust particulates in snow were analyzed separately. Additionally, snow chamber simulations were run to assess snow characteristics that would lead to increased 4NP deposition in snow. Wind speed was found to correlate inversely with 4NP deposition. Snowflake size showed a positive correlation with 4NP deposition due to increasing surface area. The amount of dust in snow was poorly correlated with 4NP concentration. A geospatial model was developed for the Eastern Sierra Nevada using ArcGIS software that included wind speed, snowflake size, and topographic shielding. Regions that were predicted to be at high risk for 4NP deposition correlated strongly with empirical data from the field.

Rare earth element (REE) geochemistry of the basaltic rocks (gabbro) in Ameta were studied inorder to determine the fractionation pattern of the magma that form the rocks and as well to determine the economic potential of the REE in the rocks. The field occurrence of the basaltic rock shows evidence of decrease in the thermal effects of the magma. Presence of phenocrysts of mafic minerals (biotite and olivine) in the rocks indicate slow rate of cooling of the magma that gave rise to the rocks. Field occurrence depicts that crystallization of the magma closed the vent through which the magma erupted thereby making the rocks to appear as plutons. The rare earth element geochemistry of the rocks shows the fractionating pattern of the magma. The REE is characterized by a sloping pattern which indicates the trend of the fractionation. There are enrichment of most of the light rare earth elements (LREE) and depletion of the heavy rare earth element (HREE). There are slight negative Eu anomalies in the rocks which defines the level of plagioclase fractionation. The concentration of REE in the rocks have shown the economic potentials of the rocks. REE is useful natural resource for 21st century technology.

A number of environmental risk factors have been reported to be associated with elevated blood glucose and diabetes. However, these associations have primarily been explored in Western populations and few studies have examined diabetic risk factors in novel populations such as the Caribbean. We examined whether exercise and food consumption is associated with blood glucose levels in the Caribbean population of Sint Maarten. Using cross-sectional data from Project HELP (Health, Education, Literacy, and Prevention), a collaboration between the American University of the Caribbean School of Medicine and Sint Maarten Ministry of Health, we estimated two logistic regression models predicting elevated blood glucose. The adjusted model included demographic, biological, and social/ behavioral covariates. Unhealthy food consumption was associated with decreased odds of elevated blood glucose in the first model (OR=0.19, p=0.04) but not significant in the adjusted model. All other factors were not significantly associated with blood glucose. It seems that the traditional environmental risk factors – such as exercise and diet – associated with blood glucose in most Western populations are not significant in Sint Maarten. Further research must be conducted to determine appropriate risk factors for this population and possibly other Caribbean populations.

The study area experiences the sea water influx during high tide and fresh water during rainfall, flooding season etc. The Creek area is beset mostly with dwarf mangroves on either side, aquaculture ponds, agriculture fields, saltpans etc. The Creek life is influenced by these activities either directly or indirectly throughout the year. It is an almost unexplored area and is represented with diverse fauna and flora. In observation of that, the current investigation was undertaken to study the status of bioaccumulation of heavy metals, specifically Cu, Cd, Zn, Pb, Ni and Fe in soft tissues namely, in foot, digestive caecum, total body and operculum and shells of three different species of molluscs namely Telescopium telescopium, Cerithidea obtusa and Cerithidea cingulata using the Flame Atomic Absorption Spectrophotometer. All the outcomes were expressed in μg/gram of dry weight and the end result reveals reflective amounts of heavy metals, except Cd, Pb and Ni. The statistical analysis of all in vitro studies of heavy metal concentration within and in between the matching organs of all tested species with oneway ANOVA showed significant difference except one. It can be concluded that, although molluscs provide information on the bioavailability of contaminants in ecosystems, it is hardly possible to derive any predictions of biological effects of these pollutants at the given level of exposure; such predictions are the main perspectives of biological effect monitoring.

Nanoparticles are widely used in the biotechnology and biomedical field. Their large surface area, remarkable physical properties, enhanced permeability, and retention effect make them as promising candidates in biomedical applications such as diagnosis and therapy. The gold and silver nanoparticles proved to be the safest for drug applications. The gold and silver nanoparticles are considered very important and interesting for several applications. This review provides a summary of Au and Ag nanoparticles synthesis, characterization, and applications. The review will focus on the use of nanoparticles in drug delivery and in determining and sensing of drugs in pharmaceuticals.

There is a plethora of articles and studies regarding the emerging and rapidly spreading mosquito borne Zika virus vectored by the Aedes egyptii mosquito. This article focuses on the methods used for mosquito control to reduce the the spread of mosquito borne viruses such as dengue, malaria and Zika virus with speculation regarding the origin and spread of the Zika virus. Other sources of what may have caused the same results as the Zika virus are explored, i.e., what chemicals in the water or crops may have polluted the water or infected the mosquitos through cross-transmission from crops to mosquitoes to simian species to humans that may result in deformities and neurological damage?

Trace amount of elements are common in water, some of these elements may be hazardous to human health and others may be vital to human body. Using inductively coupled plasma-optical emission spectrometry (ICP-OES) technique after 10-fold pre-concentration and acid digestion, the concentrations of 10 trace elements samples (TEs) Ba, Cu, Cr, Ni, V, Mn, Mo, Ag, P and Si were determined in drinking water in Turabah Province (Saudi Arabia). The concentrations of Cu, Cr, Ni, V, Mn, Mo, Ag and P in the samples of local and national factories were found to be below the maximum level that that recommended by World Health Organization (WHO) and Saudi Arabia Standards Organization (SASO). While, the concentrations of Ba was above and below the maximum level that recommended by WHO and SASO according to the sample source. The concentrations of Ba, Cu, Cr, Ni, V, Mo, Ag, and P in the wells samples were below the maximum level, while the concentrations of Mn was above the maximum level. The analysis method was validated in terms of accuracy, precision, limit of detection (LOQ) and limit of quantification (LOD) and confirmation reliability. The recovery percent was found to be 97.5 -99.7%.

Recently, there is increasing evidences supported by animal studies emphasizing that exposure to environmental factors, nutritional conditions, xenobiotic chemicals, reproductive factors and low dose exposure to radiations can alter epigenetic programming and concomitantly enhance the risk of developing diseases. Endocrine disrupting chemicals (EDCs) can influence organization of developing brain, which may appear in expression of species typical social behaviors. Environmental exposures to EDCs are shown to increase the susceptibility against many kind of diseases. Currently, there are already several articles, books and journals about the epigenetic effects of EDCs available in media and internet. The aim of this thesis is to review these articles and to evaluate the possible consequences of being exposed to these agents in our daily life for the process of risk assessment of these chemicals. Epigenetic effects do not change the gene sequence. They affect the gene expression and therefore identification of expression profile in sensitive genes to epigenetic effects may be used as a biomarker for disease and environmental exposure. In the future, theses epigenetic biomarkers may help for early diagnosis of sensitivity of an individual for adult onset disease or maybe used to prevent the disease before the disease’s symptoms develop. When an organism grows and develops, precisely organized chemical reactions activate or deactivate parts of the genome at specific time and locations. The study of these chemical reactions and factors influencing them is called epigenetics. It has been observed that, transgenerationally modified progenies in their life are more prone to different kinds of diseases, such as mammary tumors, prostate disease, kidney disease, testis abnormalities and immune abnormalities. Our health depends on our normal development and reproductive ability. Healthy endocrine system is needed to have normal development and normal reproduction. Few years ago we thought that our life starts with the DNA we receive from our parents, but currents studies have shown that we receive more than just DNA from our parents. Famine, stress, fear and even drug use could all leave chemical marks on parent’s genetic material. Environmental exposure to EDCs during early development and pregnancy can modify epigenomes and induce trans-generationally asthma, autism, cancer, cardiovascular dysfunctions, diabetes, obesity, schizophrenia, infertility, reproductive diseases and dysfunction later in life. There is evidence showing that EDCs can induce epigenetic gene alterations by which these altered genes can be transferred into subsequent generations.

The fouling process is an ecologically complex web of interactions between basibionts e.g., corals, surface-colonizing microbes e.g., bacteria, and fouling biota e.g., Balanus species which are all mediated by chemical signalling. Sessile invertebrates, such as soft corals, sponges and sea cucumbers, evolved in an intense competitive milieu for space, light and nutrients, therefore they have developed chemical defence mechanism by producing secondary metabolites e.g., Terpenes to ward off bio-foulers and maintain clean body surfaces. The settlement of surface-colonizing organisms, commonly referred to as bio-fouling organisms, occurs naturally in a turbulent environment, yet the effects of waterborne versus surface-adsorbed chemical defences have not been compared in flow, therefore limiting our understanding of how they respond to toxic surfaces of the basibionts. Here, we reviewed the evidence that basibionts chemically inhibit the propagules of fouling organisms under natural conditions, and that chemosensory mechanisms may allow the larvae of bio-fouling animals to detect and avoid settling on chemically protected basibionts.

Elemental mercury in the atmospheric environment has been identified as a significant environmental issue. The primary reason is the increased anthropogenic emissions of this metal into the global atmospheric environment in recent years. This paper provides a review for elemental mercury uptake in a flue gas stream. The objectives are to provide a summary of the carbon materials and effective parameters involved in an elemental mercury emission flue gas stream control system for industry. Activated carbon injection systems into emission stacks of coal fired power plant have been credited with providing a significant elemental mercury emission control technology. Various chemicals including sulfur, halogens and others species have been identified as key capture agents for elemental mercury emission control on an activated carbon. With the successes of the past several years, there is in place an excellent frame work in the literature to build an activated carbon injection control system to further increase the efficiency of uptake for elemental mercury from mixed gas streams.