Amjad Shraim

A global health problem caused by arsenic from natural sources

Arsenic is a carcinogen to both humans and animals. Arsenicals have been associated with cancers of the skin, lung, and bladder. Clinical manifestations of chronic arsenic poisoning include non-cancer end point of hyper- and hypo-pigmentation, keratosis, hypertension, cardiovascular diseases and diabetes. Epidemiological evidence indicates that arsenic concentration exceeding 50 microg l(-1) in the drinking water is not public health protective. The current WHO recommended guideline value for arsenic in drinking water is 10 microg l(-1), whereas many developing countries are still having a value of 50 microg l(-1). It has been estimated that tens of millions of people are at risk exposing to excessive levels of arsenic from both contaminated water and arsenic-bearing coal from natural sources. The global health implication and possible intervention strategies were also discussed in this review article.

Speciation of arsenic by hydride generation-atomic absorption spectrometry (HG-AAS) in hydrochloric acid reaction medium

The effects on the absorbance signals obtained using HG-AAS of variations in concentrations of the reaction medium (hydrochloric acid), the reducing agent [sodium tetrahydroborate(III); NaBH(4)], the pre-reducing agent (l-cysteine), and the contact time (between l-cysteine and arsenic-containing solutions) for the arsines generated from solutions of arsenite, arsenate, monomethylarsonic acid (MMA), and dimethylarsenic acid (DMA), have been investigated to find a method for analysis of the four arsenic species in environmental samples. Signals were found to be greatly enhanced in low acid concentration in both the absence (0.03-0.60 M HCl) and the presence of l-cysteine (0.001-0.03 M HCl), however with l-cysteine present, higher signals were obtained. Total arsenic content and speciation of DMA, As(III), MMA, and As(V) in mixtures containing the four arsenic species, as well as some environmental samples have been obtained using the following conditions: (i) total arsenic: 0.01 M acid, 2% NaBH(4), 5% l-cysteine, and contact time<10 min; (ii) DMA: 1.0 M acid, 0.3-0.6% NaBH(4), 4.0% l-cysteine, and contact time <5 min; (iii) As(III): 4-6 M acid and 0.05% NaBH(4) in the absence of l-cysteine; (iv) MMA: 4.0 M acid, 0.03% NaBH(4), 0.4% l-cysteine, and contact time of 30 min; (v) As(V): by difference. Detection limits (ppb) for analysis of total arsenic, DMA, As(III), and MMA were found to be 1.1 (n=7), 0.5 (n=5), 0.6 (n=7), and 1.8 (n=4), respectively. Good percentage recoveries (102-114%) of added spikes were obtained for all analyses.

Arsenic speciation in the urine and hair of individuals exposed to airborne arsenic through coal-burning in Guizhou, PR China

The extent of exposure of residents of Changqing (Guizhou, PR China) to arsenic through coal-burning was investigated. Despite the low coal-arsenic content (56.3+/-42.5 mg As kg(-1)) when compared with coals collected at different location and times from the same province, more than 30% of the study subjects have shown symptoms of arsenicosis. Coal, urine, hair, and water samples were collected in mid-September 2001 and analysed for arsenic. The average urinary and hair-arsenic concentrations in the exposed subjects were 71.4+/-37.1 microg As g(-1) creatinine (control 41.6+/-12.1) and 7.99+/-8.16 mg kg(-1), respectively. A positive correlation between the hair and urinary-arsenic concentration (R(2)=0.601) was found. There was no significant difference between females and males for both urinary and hair-arsenic concentrations. Females were found to have a higher dimethylarsinic acid but lower percentages of inorganic arsenic and monomethylarsonic acid in their urine than males.

Subchronic Exposure to Arsenic Through Drinking Water Alters Expression of Cancer-Related Genes in Rat Liver

Although arsenic exposure causes liver disease and/or hepatoma, little is known about molecular mechanisms of arsenic-induced liver toxicity or carcinogenesis. We investigated the effects of arsenic on expression of cancer-related genes in a rat liver following subchronic exposure to sodium arsenate (1, 10, 100 ppm in drinking water), by using real-time quantitative RT-PCR and immunohistochemical analyses. Arsenic accumulated in the rat liver dose-dependently and caused hepatic histopathological changes, such as disruption of hepatic cords, sinusoidal dilation, and fatty infiltration. A 1-month exposure to arsenic significantly increased hepatic mRNA levels of cyclin D1 (10 ppm), ILK (1 ppm), and p27Kip1 (10 ppm), whereas it reduced mRNA levels of PTEN (1 ppm) and β-catenin (100 ppm). In contrast, a 4-month arsenic exposure showed increased mRNA expression of cyclin D1 (100 ppm), ILK (1 ppm), and p27Kip1 (1 and 10 ppm), and decreased expression of both PTEN and β-catenin at all 3 doses. An immunohistochemical study revealed that each protein expression accords closely with each gene expression of mRNA level. In conclusion, subchronic exposure to inorganic arsenate caused pathological changes and altered expression of cyclin D1, p27Kip1, ILK, PTEN, and β-catenin in the liver. This implies that arsenic liver toxicity involves disturbances of some cancer-related molecules.

A Randomised intervention trial to assess two arsenic mitigation options in Bangladesh

Arsenic groundwater contamination in Bangladesh warrants immediate remediation. This randomised controlled intervention trial was conducted to determine the effectiveness of two possible interventions: dug wells and three-pitcher filters. A total of 640 individuals participated with 218 randomised to the dug well group, 216 to the three-pitcher group and 206 to a control group. Data were collected at baseline and at 1, 6 and 12 months after the intervention. Self reported compliance with dug wells remained below 20% during the entire 12 months of the study. The compliance with the three-pitcher filters decreased after 6 months and became similar to the compliance of the dug well group after 12 months. A substantial decrease in urinary arsenic metabolites occurred only among those who were compliant with dug wells and three-pitcher filter systems after 1 month of intervention as opposed to control participants. However, a persistent reduction in urinary arsenic concentrations was observed only among the dug well users after 12 months of intervention. Our results show that a functional dug well could be offered as a long-term alternative to tube wells, but use of this option is likely to be low, unless appropriate behavioural change measures are taken. Our study also demonstrates that arsenic removal technologies such as three-pitcher filters are an effective option as a short-term measure. The three-pitcher filters that are not adequately maintained are not an effective option for a year. These arsenic removal technologies may be even harmful in the long term if the resultant water quality is not properly monitored.

Aerobic sludge granulation at high temperatures for domestic wastewater treatment

With inoculum sludge from a conventional activated sludge wastewater treatment plant, three sequencing batch reactors (SBRs) fed with synthetic wastewater were operated at different high temperatures (30, 40 and 50±1°C) to study the formation of aerobic granular sludge (AGS) for simultaneous organics and nutrients removal with a complete cycle time of 3h. The AGS were successfully cultivated with influent loading rate of 1.6CODg(Ld)(-1). The COD/N ratio of the influent wastewater was 8. The results revealed that granules developed at 50°C have the highest average diameter, (3.36mm) with 98.17%, 94.45% and 72.46% removal efficiency observed in the system for COD, ammonia and phosphate, respectively. This study also demonstrated the capabilities of AGS formation at high temperatures which is suitable to be applied for hot climate conditions.

LIGAND-METAL INTERACTIONS AND EXCITED-STATE PROPERTIES IN RUTHENIUM(II)-DIIMINE COMPLEXES

Abstract 2,2′-Bipyridine (bpy); 2,2′-bipyrazine (bpz); 5,6-dimethyl-2,3-di-(2′-pyridyl)-quinoxaline (dbpq); 4,4′- dimethyl-2,2′-bipyridine (dmbpy), 2,3-di-(2′- pyridyl)-pyrazine (dpp); 3,3′-bipyridazine (bpd); 2,3-di-(2′- pyridyl)-quinoxaline (dpq) and 2-(2′-pyridyl)-quinoline (pyq) form mixed-ligand complexes with Ru(II). The excited state properties (emission, lifetimes and redox potentials) are reported and analyzed in the framework of solar energy conversion. Ligand σ- and π-bonding properties are also deduced.

CONTROLLED SYNTHESIS OF SOME MIXED DIIMINE RUTHENIUM(II) COMPLEXES

Complexes of a series of mixed ligands with ruthenium have been prepared and characterized through dihalide replacement in Ru(bpy)2Cl2, Ru(bpz)2Cl2 and tetrahalide replacement in HRu(bpy)Cl4(bpy = 2,2′-bipyridine; bpz = 2,2′-bipyrazine) by one or two bidentate ligands of the diimine type namely, bpd, dbpq and dpp (bpd = 3,3′bipyridazine; dbpq = 6,7-dimethyl-2,3-bis-(2′-pyridyl)-quinoxaline; dpp = 2,3-bis-(2-pyridyl)-pyrazine). The ruthenium dimer [(bpy)2Ru(dbpq)Ru(bpy)2](PF6)4·3H2O, as well as the tris-complex [Ru(dbpq)3](PF6)2·H2O, were also prepared and characterized.

A randomised intervention trial to assess two arsenic mitigation options in Bangladesh

Arsenic groundwater contamination in Bangladesh warrants immediate remediation. This randomised controlled intervention trial was conducted to determine the effectiveness of two possible interventions: dug wells and three-pitcher filters. A total of 640 individuals participated with 218 randomised to the dug well group, 216 to the three-pitcher group and 206 to a control group. Data were collected at baseline and at 1, 6 and 12 months after the intervention. Self reported compliance with dug wells remained below 20% during the entire 12 months of the study. The compliance with the three-pitcher filters decreased after 6 months and became similar to the compliance of the dug well group after 12 months. A substantial decrease in urinary arsenic metabolites occurred only among those who were compliant with dug wells and three-pitcher filter systems after 1 month of intervention as opposed to control participants. However, a persistent reduction in urinary arsenic concentrations was observed only among the dug well users after 12 months of intervention. Our results show that a functional dug well could be offered as a long-term alternative to tube wells, but use of this option is likely to be low, unless appropriate behavioural change measures are taken. Our study also demonstrates that arsenic removal technologies such as three-pitcher filters are an effective option as a short-term measure. The three-pitcher filters that are not adequately maintained are not an effective option for a year. These arsenic removal technologies may be even harmful in the long term if the resultant water quality is not properly monitored.

Urinary arsenic speciation as a tool to assess the efficacy of two drinking water interventions in Bangladesh

We have estimated of the maximum radiation dose received from consuming an oyster at Hiroshima following the A-bomb detonation in 1945