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May

12

2019

    SCIENCE & TECHNOLOGY

    Arsenic Contamination

    News: NBRI: Arsenic bioremediation using two soil bacteria.
    Source: The Hindu

    Arsenic is naturally present at high levels in the groundwater of a number of countries.

    Arsenic is highly toxic in its inorganic form.

    Arsenic is highly toxic in its inorganic form.

    Contaminated water used for drinking, food preparation and irrigation of food crops poses the greatest threat to public health from arsenic.

    Long-term exposure to arsenic from drinking-water and food can cause cancer and skin lesions. It has also been associated with cardiovascular disease and diabetes. In utero and early childhood exposure has been linked to negative impacts on cognitive development and increased deaths in young adults.

    The most important action in affected communities is the prevention of further exposure to arsenic by provision of a safe water supply.

    Arsenic is a natural component of the earth’s crust and is widely distributed throughout the environment in the air, water and land. It is highly toxic in its inorganic form.

    People are exposed to elevated levels of inorganic arsenic through drinking contaminated water, using contaminated water in food preparation and irrigation of food crops, industrial processes, eating contaminated food and smoking tobacco.

    Long-term exposure to inorganic arsenic, mainly through drinking-water and food, can lead to chronic arsenic poisoning. Skin lesions and skin cancer are the most characteristic effects.

    Drinking-water and food

    The greatest threat to public health from arsenic originates from contaminated groundwater. Inorganic arsenic is naturally present at high levels in the groundwater of a number of countries, including Argentina, Bangladesh, Chile, China, India, Mexico, and the United States of America. Drinking-water, crops irrigated with contaminated water and food prepared with contaminated water are the sources of exposure.

    Fish, shellfish, meat, poultry, dairy products and cereals can also be dietary sources of arsenic, although exposure from these foods is generally much lower compared to exposure through contaminated groundwater. In seafood, arsenic is mainly found in its less toxic organic form.

    Industrial processes

    Arsenic is used industrially as an alloying agent, as well as in the processing of glass, pigments, textiles, paper, metal adhesives, wood preservatives and ammunition. Arsenic is also used in the hide tanning process and, to a limited extent, in pesticides, feed additives and pharmaceuticals.

    Tobacco

    People who smoke tobacco can also be exposed to the natural inorganic arsenic content of tobacco because tobacco plants can take up arsenic naturally present in the soil. Also, in the past, the potential for elevated arsenic exposure was much greater when tobacco plants used to be treated with lead arsenate insecticide.

    Health effects

    Inorganic arsenic is a confirmed carcinogen and is the most significant chemical contaminant in drinking-water globally. Arsenic can also occur in an organic form. Inorganic arsenic compounds (such as those found in water) are highly toxic while organic arsenic compounds (such as those found in seafood) are less harmful to health.

    Acute effects

    The immediate symptoms of acute arsenic poisoning include vomiting, abdominal pain and diarrhoea. These are followed by numbness and tingling of the extremities, muscle cramping and death, in extreme cases.

    Long-term effects

    The first symptoms of long-term exposure to high levels of inorganic arsenic (for example, through drinking-water and food) are usually observed in the skin, and include pigmentation changes, skin lesions and hard patches on the palms and soles of the feet (hyperkeratosis). These occur after a minimum exposure of approximately five years and may be a precursor to skin cancer.

    In addition to skin cancer, long-term exposure to arsenic may also cause cancers of the bladder and lungs. The International Agency for Research on Cancer (IARC) has classified arsenic and arsenic compounds as carcinogenic to humans, and has also stated that arsenic in drinking-water is carcinogenic to humans.

    Other adverse health effects that may be associated with long-term ingestion of inorganic arsenic include developmental effects, diabetes, pulmonary disease, and cardiovascular disease. Arsenic-induced myocardial infarction, in particular, can be a significant cause of excess mortality. In China (Province of Taiwan), arsenic exposure has been linked to “Blackfoot disease”, which is a severe disease of blood vessels leading to gangrene. This disease has not been observed in other parts of the world however, and it is possible that malnutrition contributes to its development.

    Arsenic is also associated with adverse pregnancy outcomes and infant mortality, with impacts on child health (1), and exposure in utero and in early childhood has been linked to increases in mortality in young adults due to multiple cancers, lung disease, heart attacks, and kidney failure (2). Numerous studies have demonstrated negative impacts of arsenic exposure on cognitive development, intelligence, and memory (3).

    Fast Neutrino Oscillations May Hold Key To Supernovae Formation

    News: Fast neutrino oscillations may hold key to supernovae formation.
    Source: The Hindu

    Neutrinos could be the driving force behind supernova explosions, a new theoretical study from Tata Institute of Fundamental Research finds. The study which makes a fundamental advance in modelling neutrinos inside stars puts forth the idea that “fast neutrino oscillations” could hold the key to why some stars explode forming supernovae at the end of their lives.

    Neutrinos come in three flavours: electron neutrino, muon neutrino and tau neutrino, so named because of the corresponding leptons they are associated with (electron, muon and tau). There are several puzzles they have posed, including how they are ordered according to mass and this puzzle still remains to be solved.

    Earlier when measuring the number of neutrinos coming from the sun, experimentalists found that only a third of the number of solar neutrinos that was expected was being intercepted.

    on earth. This was later explained by the understanding that they have a small mass and they can change from one flavour to another – a phenomenon named neutrino oscillations.

    Fast neutrino oscillations are another phenomenon – When the same neutrinos are in the presence of many other neutrinos and when the different flavours are emitted slightly differently in various directions (anisotropy) the oscillations from one flavour to another happen at a higher frequency. This is called fast oscillation and is proportional to the density of neutrinos in the medium, and not the masses of the neutrinos.

    ‘Rain-Loving’ Snake Discovered In Mizoram- Smithophis Atemporalis

    News: ‘Rain-loving’ snake discovered in Mizoram.
    Source: The Hindu

    It’s literally raining reptiles in the Northeast, and the latest to be discovered has a Mizo name that means rain-loving.

    A month after a Russian journal published the discovery of a reddish-brown pit viper in Arunachal Pradesh, the New Zealand-based journal Zootaxa has come out with the discovery of a non-venomous snake in Mizoram.

    The discovery of another non-venomous snake species — the Crying Keelback, in Arunachal Pradesh’s Lepa-Rada district, was published in an international journal about six months ago.

    Based on DNA and morphology, the study established that the two species are not at all closely related and what was once considered to be a single species from the Northeast, are actually two distinct species. While the species from the Western Ghats continues to remain in the genus Rhabdops, the two species from the Northeast have been assigned to a new genus — Smithophis.

    The species from Mizoram lacks specific enlarged scales in the temporal region of the head. This character is extremely rare in snakes of this family, hence its name Smithophisatemporalis or the Mizo rain snake.

    INTERNATIONAL RELATION

    180 Nations Agree On A New Un Accord To Curb Export Of Plastic Waste

    News: 180 nations agree on a new UN accord to curb export of plastic waste.
    Source: The Hindu

    Around 180 governments agreed on a new UN accord to regulate the export of plastic waste, some eight million tonnes of which ends up in the oceans each year.

    The Geneva meeting amended the 1989 Basel Convention on the control of hazardous wastes to include plastic waste in a legally-binding framework.

    The IPEN umbrella group seeking to eliminate hazardous and toxic chemicals said the new amendment would empower developing countries to refuse “dumping plastic waste” by others.

    Plastic waste pollution has reached “epidemic proportions” with an estimated 100 million tonnes of plastic now found in the oceans.

    The a meeting also undertook to eliminate two toxic chemical groups — Dicofol and Perfluorooctanoic Acid, plus related compounds. The latter has been used in a wide variety of industrial and domestic applications including non-stick cookware and food processing equipment, as well as carpets, paper and paints.