Global prevalence of glaucoma and projections of glaucoma burden through 2040: a systematic review and meta-analysis.

Arsenic removal from water/wastewater using adsorbents—A critical review

The contamination of groundwater by arsenic in Bangladesh is the largest poisoning of a population in history, with millions of people exposed. This paper describes the history of the discovery of arsenic in drinking-water in Bangladesh and recommends intervention strategies. Tube-wells were installed to provide ‘‘pure water’’ to prevent morbidity and mortality from gastrointestinal disease. The water from the millions of tube-wells that were installed was not tested for arsenic contamination. Studies in other countries where the population has had long-term exposure to arsenic in groundwater indicate that 1 in 10 people who drink water containing 500mg of arsenic per litre may ultimately die from cancers caused by arsenic, including lung, bladder and skin cancers. The rapid allocation of funding and prompt expansion of current interventions to address this contamination should be facilitated. The fundamental intervention is the identification and provision of arsenic-free drinking water. Arsenic is rapidly excreted in urine, and for early or mild cases, no specific treatment is required. Community education and participation are essential to ensure that interventions are successful; these should be coupled with follow-up monitoring to confirm that exposure has ended. Taken together with the discovery of arsenic in groundwater in other countries, the experience in Bangladesh shows that groundwater sources throughout the world that are used for drinking-water should be tested for arsenic.

/pdf/contamination-of-drinking-water-by-arsenic-in-bangladesh-a-15o8nvbvr0.pdf

Contamination of drinking-water by arsenic in Bangladesh: a public health emergency

http://ntur.lib.ntu.edu.tw/bitstream/246246/175878/1/19.pdf

Application of factor analysis in the assessment of groundwater quality in a blackfoot disease area in Taiwan

Arsenic is a metalloid whose name conjures up images of murder. Nonetheless, certain prokaryotes use arsenic oxyanions for energy generation, either by oxidizing arsenite or by respiring arsenate. These microbes are phylogenetically diverse and occur in a wide range of habitats. Arsenic cycling may take place in the absence of oxygen and can contribute to organic matter oxidation. In aquifers, these microbial reactions may mobilize arsenic from the solid to the aqueous phase, resulting in contaminated drinking water. Here we review what is known about arsenic-metabolizing bacteria and their potential impact on speciation and mobilization of arsenic in nature.

https://science.sciencemag.org/content/sci/300/5621/939.full.pdf

The Ecology of Arsenic

The natural contamination of drinking water by arsenic needs to be urgently addressed. The pollution by naturally occurring arsenic of alluvial Ganges aquifers, which are used for the public water supply in Bangladesh and West Bengal, has been discussed by Nickson
 et al.1. We agree with their main conclusion that arsenic is released by reductive dissolution of iron oxyhydroxides, as was proposed earlier2. Our observations indicate that arsenic- rich pyrite and other arsenic minerals, which were proposed in previous models (cited by Nickson et al.1) to give rise to arsenic pollution, are rare or even absent in the sediments of the Ganges delta. We believe that arsenic is more likely to be co-precipitated with or scavenged by iron (III) and manganese (IV) in the sedimentary environment.

Arsenic poisoning in the Ganges delta

Arsenic toxicity in groundwater in the Ganges delta and some low-lying areas in the Bengal basin is confined to middle Holocene sediments. Dissected terraces and highlands of Pleistocene and early Holocene deposits are free of such problems. Arsenic-rich pyrite or other arsenic minerals are rare or absent in the affected sediments. Arsenic appears to occur adsorbed on iron hydroxide-coated sand grains and clay minerals and is transported in soluble form and co-precipitated with, or is scavenged by, Fe(III) and Mn(IV) in the sediments. It became preferentially entrapped in fine-grained and organic-rich sediments during mid-Holocene sea-level rises in deltaic and some low-lying areas of the Bengal basin. It was liberated subsequently under reducing conditions and mediated further by microbial action. Intensive extraction of groundwater for irrigation and application of phosphate fertilizer possibly triggered the recent release of arsenic to groundwater. This practice has induced groundwater flow, mobilizing phosphate derived from fertilizer, as well as from decayed organic matter, which has promoted the growth of sediment biota and aided the further release of arsenic. However, the environment is not sufficiently reducing to mobilize iron and arsenic in groundwater in the Ganges floodplains upstream of Rajmahal. Thus, arsenic toxicity in the groundwater of the Bengal basin is caused by its natural setting, but also appears to be triggered by recent anthropogenic activities.

Arsenic toxicity of groundwater in parts of the Bengal basin in India and Bangladesh: the role of Quaternary stratigraphy and Holocene sea-level fluctuation

Aim: To determine (i) the prevalence of glaucoma in people aged ⩾50 years, (ii) the proportions of different types of glaucoma, (iii) the distributions of intraocular pressure and vertical cup disc ratio. Method: Population based prevalence survey in rural West Bengal. People aged ⩾50 years in randomly selected villages in 24 Parganas South district. The main outcome measures were diagnosis of glaucoma, based on criteria described by the International Society for Geographic and Epidemiological Ophthalmology. Results: 1594 people aged ⩾50 years were enumerated in nine villages; 1324 (83.1%) were surveyed and 1269 people adequately examined. 42 definite cases of glaucoma were identified, with prevalence increasing from 2.7% (95% CI 1.7 to 3.7) in people aged 50–59 years to 6.5% (95% CI 0.0 to 14.1) in those aged ⩾80 years. The age standardised estimate for the prevalence of all glaucoma in people aged ⩾50 years was 3.4%. Only three cases of primary angle closure glaucoma (PACG) were identified, giving a crude ratio of primary open angle glaucoma (POAG) to PACG of more than 10:1. Three people with glaucoma were blind in one eye but none was blind in both eyes. Conclusion: Compared to other surveys of glaucoma in India, the age standardised prevalence observed was less than in Hyderabad, but similar to Tamil Nadu and Dhaka. The ratio of POAG to PACG was much higher than found previously, suggesting that PACG may be less prevalent in Bengalis than in Indian populations living in south India. The authors conclude that ophthalmic services in West Bengal should focus on detecting POAG. Since there is still no satisfactory method of screening for POAG, there is no alternative to case detection (opportunistic screening) in eye clinics.

https://bjo.bmj.com/content/bjophthalmol/89/12/1559.full.pdf

A population based survey of the prevalence and types of glaucoma in rural West Bengal: the West Bengal Glaucoma Study.

Paraplegia complicating a block of the coeliac plexus with 6% aqueous phenol for carcinoma of the pancreas is described. The patient had no previous neurological abnormality and it is postulated that vascular ischaemia of the spinal cord was responsible for the sequence of neurological events.

Paraplegia following coeliac plexus block with phenol

The antacid properties of 0.3 molar sodium citrate have been studied. Aniseed-flavoured sodium citrate has been used as an oral antacid in 22 patients undergoing general anaesthesia for emergency obstetric procedures. The results of this study show that it is a successful prophylactic agent in reducing the acidity of gastric contents. It is especially suitable for single-dose use in emergency situations where long-term prophylactic measures have not been practised.

Saibendu Kumar Lahiri

Papers

Arsenic poisoning in the Ganges delta

Arsenic toxicity of groundwater in parts of the Bengal basin in India and Bangladesh: the role of Quaternary stratigraphy and Holocene sea-level fluctuation

A population based survey of the prevalence and types of glaucoma in rural West Bengal: the West Bengal Glaucoma Study.

Paraplegia following coeliac plexus block with phenol

Single-dose antacid therapy for the prevention of mendelson's syndrome