Significance of the prime factors regulating arsenic toxicity and associated health risk: a hypothesis-based investigation in a critically exposed population of West Bengal, India.

The suffering from arsenic toxicity is a long-standing concern in Asian countries. The role of the key factors (arsenic intake, age and sex) regulating arsenic toxicity is aimed to evaluate for a severely exposed population from Murshidabad district, West Bengal. Mean arsenic concentrations in drinking water supplied through tube well, Sajaldhara treatment plant and pipeline were observed as 208, 27 and 54 µg/l, respectively. Urinary arsenic concentration had been observed as < 3-42.1, < 3-56.2 and < 3-80 µg/l in children, teenagers and adults, respectively. Mean concentrations of hair and nail arsenic were found to be 0.84 and 2.38 mg/kg; 3.07 and 6.18 mg/kg; and 4.41 and 9.07 mg/kg, respectively, for the studied age-groups. Water arsenic was found to be associated with hair and nail (r = 0.57 and 0.60), higher than urine (r = 0.37). Arsenic deposition in biomarkers appeared to be dependent on age; however, it is independent of sex. Principal component analysis showed a direct relationship between dietary intake of arsenic and chronic biomarkers. Nail was proved as the most fitted biomarker of arsenic toxicity by Dunn's post hoc test. Monte Carlo sensitivity analysis and cluster analysis showed that the most significant factor regulating health risk is 'concentration of arsenic' than 'exposure duration', 'body weight' and 'intake rate'. The contribution of arsenic concentration towards calculated health risk was highest in teenagers (45.5-61.2%), followed by adults (47.8-49%) and children (21-27.6%). Regular and sufficient access to arsenic-safe drinking water is an immediate need for the affected population.

Rice seed (IR64) priming with potassium humate for improvement of seed germination, seedling growth and antioxidant defense system under arsenic stress.

The intolerable levels of arsenic (As) in groundwater and its application in rice cultivation are continuously affecting the rice production in Ganga-Meghna-Brahmaputra (GMB) plain. The reduced germination and plant growth rates under excessive As stress ultimately lead to lower yield. To mitigate this concerning issue, the present study was carried out to evaluate the potential of K-humate priming on seed germination and plant growth under As stress. Seeds were primed with 100 mg/l K-humate for 12 h prior to germination. The germination percentages in unprimed seeds were 65 ±â€¯5.0% and 58.3 ±â€¯7.6% under stress level of 50 µM AsV and 50 µM AsIII, respectively. However, germination percentage in K-humate primed seeds were 75 ±â€¯5.0% and 68.3 ±â€¯2.9% under AsV and AsIII stress, respectively. The vigour index I (VG I) and vigour index II (VG II) recorded on 12 DAS (days after seeding) were also increased by 1.47 and 1.51 fold, respectively with K-humate supplementation under As stress. Detrimental effects of AsIII on seed germination, seedling growth and other physiological parameters were more suppressive than AsV. Application of K-humate not only improved seed germination, seedling growth and nutrient uptake but also decreased the oxidative stress markers and antioxidant activities by minimizing As uptake and translocation in the seedlings.

Health effect and risk assessment of the populations exposed to different arsenic levels in drinking water and foodstuffs from four villages in arsenic endemic Gaighata block, West Bengal, India.

Health exposure and perception of risk assessment have been evaluated on the populations exposed to different arsenic levels in drinking water (615, 301, 48, 20 µg/l), rice grain (792, 487, 588, 569 µg/kg) and vegetables (283, 187, 238, 300 µg/kg) from four villages in arsenic endemic Gaighata block, West Bengal. Dietary arsenic intake rates for the studied populations from extremely highly, highly, moderately, and mild arsenic-exposed areas were 56.03, 28.73, 11.30, and 9.13 µg/kg bw/day, respectively. Acute and chronic effects of arsenic toxicity were observed in ascending order from mild to extremely highly exposed populations. Statistical interpretation using 'ANOVA' proves a significant relationship between drinking water and biomarkers, whereas "two-tailed paired t test" justifies that the consumption of arsenic-contaminated dietary intakes is the considerable pathway of health risk exposure. According to the risk thermometer (SAMOE), drinking water belongs to risk class 5 (extremely highly and highly exposed area) and 4 (moderately and mild exposed area) category, whereas rice grain and vegetables belong to risk class 5 and 4, respectively, for all the differently exposed populations. The carcinogenic (ILCR) and non-carcinogenic risks (HQ) through dietary intakes for adults were much higher than the recommended threshold level, compared to the children. Supplementation of arsenic-safe drinking water and nutritional food is strictly recommended to overcome the severe arsenic crisis.

Arsenic toxicity in livestock growing in arsenic endemic and control sites of West Bengal: risk for human and environment.

The present study aims to estimate geochemical arsenic toxicity in the domestic livestock and possible risk for human and environment caused by them. Daily dietary arsenic intake of an exposed adult cow or bull is nearly 4.56 times higher than control populace and about 3.65 times higher than exposed goats. Arsenic toxicity is well exhibited in all the biomarkers through different statistical interpretations. Arsenic bioconcentration is faster through water compared to paddy straw and mostly manifested in faeces and tail hair in cattle. Cow dung and tail hair are the most pronounced pathways of arsenic biotransformation into environment. A considerable amount of arsenic has been observed in animal proteins such as cow milk, boiled egg yolk, albumen, liver and meat from the exposed livestock. Cow milk arsenic is mostly accumulated in casein (83%) due to the presence of phosphoserine units. SAMOE-risk thermometer, calculated for the most regularly consumed foodstuffs in the area, shows the human health risk in a distinct order: drinking water > rice grain > cow milk > chicken > egg > mutton ranging from class 5 to 1. USEPA health risk assessment model reveals more risk in adults than in children, subsisting severe cancer risk from the foodstuffs where the edible animal proteins cannot be ignored. Therefore, the domestic livestock should be urgently treated with surface water, while provision of both arsenic-free drinking water and nutritional supplements is mandatory for the affected human population to overcome the severe arsenic crisis situation.

Different levels of arsenic exposure through cooked rice and its associated benefit-risk assessment from rural and urban populations of West Bengal, India: a probabilistic approach with sensitivity analysis.

Rice arsenic (As) contamination and its consumption poses a significant health threat to humans. The present study focuses on the contribution of arsenic, micronutrients, and associated benefit-risk assessment through cooked rice from rural (exposed and control) and urban (apparently control) populations. The mean decreased percentages of As from uncooked to cooked rice for exposed (Gaighata), apparently control (Kolkata), and control (Pingla) areas are 73.8, 78.5, and 61.3%, respectively. The margin of exposure through cooked rice (MoEcooked rice) < 1 signifies the existence of health risk for all the studied exposed and control age groups. The respective contributions of iAs (inorganic arsenic) in uncooked and cooked rice are nearly 96.6, 94.7, and 100% and 92.2, 90.2, and 94.2% from exposed, apparently control, and control areas. LCR analysis for the exposed, apparently control, and control populations (adult male: 2.1 × 10-3, 2.8 × 10-4, 4.7 × 10-4; adult female: 1.9 × 10-3, 2.1 × 10-4, 4.4 × 10-4; and children: 5.8 × 10-4, 4.9 × 10-5, 1.1 × 10-4) through cooked rice is higher than the recommended value, i.e., 1 × 10-6, respectively, whereas HQ > 1 has been observed for all age groups from the exposed area and adult male group from the control area. Adults and children from rural area showed that ingestion rate (IR) and concentration are the respective influencing factors towards cooked rice As, whereas IR is solely responsible for all age groups from urban area. A vital suggestion is to reduce the IR of cooked rice for control population to avoid the As-induced health risks. The average intake (µg/day) of micronutrients is in the order of Zn > Se for all the studied populations and Se intake is lower for the exposed population (53.9) compared to the apparently control (140) and control (208) populations. Benefit-risk assessment supported that the Se-rich values in cooked rice are effective in avoiding the toxic effect and potential risk from the associated metal (As).

Rice grain arsenic and nutritional content during post harvesting to cooking: A review on arsenic bioavailability and bioaccessibility in humans.

Rice (Oryza sativa L.) is considered as the staple food for 50% of the world's population. Humans are exposed to arsenic (As) through rice consumption, which is a global health issue that requires attention. The present review reflects the scenario of rice grown in As endemic regions of Asia that has a significant portion of inorganic As (iAs) compared to other rice grown areas around the world. Post-harvesting, pre-cooking, and cooking procedures in South and South-East Asian countries employ As-contaminated groundwater. Polishing of brown rice and parboiling, washing and cooking with As-safe water can reduce As concentration and nutrient level in cooked rice. However, in rural parts of South-east Asia, rice is usually cooked using As-contaminated groundwater and consumption of this As enriched rice and water may cause a significant health exposure in humans. Bioaccessibility and bioavailability of As can be determined using in-vitro and in-vivo techniques that can be utilized as a tool to assess As exposure in humans. Arsenic in cooked rice may be reduced by using newly developed cooking procedures such as Kateh cooking, steam percolating, and the parboiled and absorbed (PBA) method. For individuals living in rural regions, using rainwater or treated surface water for drinking and cooking is also an alternative. Although this study examined the processes involved in the post-harvesting, pre-cooking, and cooking stages, there are still significant research gaps in this area that must be addressed in near future.

Effect of sulfate application on inhibition of arsenic bioaccumulation in rice (Oryza sativa L.) with consequent health risk assessment of cooked rice arsenic on human: A pot to plate study.

Arsenic (As) in rice is posing a serious threat worldwide and consumption of As contaminated rice by human is causing health risks. A pot experiment with different levels of sulfate dosage (0, 20, 40, 60 and 80 mg/kg) was set up in this study to explore the influence of sulfate fertilizer on rice plant growth, yield, and As accumulation in rice grain. Apart from As bioaccumulation in rice grains, the As fraction of cooked rice was quantified, and the health risks associated with cooked rice consumption were also investigated. The sulfate application significantly (p ≤ 0.05) enhanced the chlorophyll, tiller number, grains per panicle, grain and biomass yield under As stressed condition. The sulfate application also reduced the oxidative stress and antioxidant activity in rice plants. Sulfate fertigation improved the accumulation of total sulfur (S) and reduced the uptake and translocation of As in rice plants. Arsenic concentration in rice grain was reduced by 50.1% in S80 treatment (80 mg of sulfate/kg of soil) as compared to S0 set. The reduction percentage of As in cooked parboiled and sunned rice with correspond to raw rice ranged from 55.9 to 74% and 40.3-60.7%, respectively. However, the sulfate application and cooking of parboiled rice reduced the potential non-cancer and cancer risk as compared to sunned rice. The S80 treatment and cooking of parboiled rice reduce the As exposure for both children and adults by 51% as compared to cooked sunned rice under S80 treatment and this trend was similar for all treatments. Therefore, sulfate application in soil can be recommended to produce safer rice grains and subsequent cooking of parboiled rice grain with low-As contaminated water need to be done to avoid any potential health risk in As endemic areas.

Application of potassium humate to reduce arsenic bioavailability and toxicity in rice plants (Oryza sativa L.) during its course of germination and seedling growth.

Arsenic (As), a metalloid is a class I carcinogen and is a major problem in various parts of the world. Food crops are severely affected due to As poisoning and suffer from low germination, yield and disfiguration of morphological and anatomical traits. To attenuate such adverse effects and tone down As uptake by plants, the present study attempts to explore the role of K-humate (KH) in alleviation of As toxicity in rice. KH was administered in the growth media containing 800 ppb As (III) at varying doses to observe the stress alleviating capacity of the amendment. Five treatments were investigated, viz: (a) 800 ppb As (control), (b) 800 ppb As + 25 ppm KH, (c) 800 ppb As + 50 ppm KH, (d) 800 ppb As + 75 ppm KH and (e) 800 ppb As + 100 ppm KH. The results of the amendment administration were noted at 14 days after seeding (DAS). Application of KH significantly improved germination percentage, vigour indices and chlorophyll content by reducing the oxidative stress, antioxidant and antioxidant enzyme activities under As stress. In vivo detection of reactive oxygen species (ROS) using DCF-2DA fluorescent dye and scanning electron microscope (SEM) study of root further depicted that KH application effectively reduced ROS formation and improved root anatomical structure under As stress, respectively. Gradually increasing concentrations of KH was capable of decreasing the bioavailability of As to the rice plants, thus minimizing toxic effect of the metalloid.

Flow of arsenic between rice grain and water: Its interaction, accumulation and distribution in different fractions of cooked rice.

Arsenic (As) contaminated water is a major threat to human health when used for drinking, cooking and irrigational purposes. Rice being consumed by 50% of the world's population, supplies considerable amount of As to the human body. Our study provides a detailed understanding of As distribution in each fraction of rice while cooking (viz. uncooked rice, cooking water, cooked rice and gruel/total discarded water), ultimately leading to a better explanation of As movement between rice grain and water. A significant decrease of As was observed in cooked rice (34-89% and 23-84% for sunned and parboiled rice respectively) when cooked with low-As containing water, <3 µg/l and moderate As-contaminated water, 36-58 µg/l (3-50% and 12-61% for sunned and parboiled rice respectively) with increasing selenium (Se) concentration. Movement of As from water to rice grain has been inferred with increasing water As (84-105 µg/l), which results in a significant increase of As in cooked rice (24-337% and 114% for sunned and parboiled rice, respectively) with decreasing Se concentration. Arsenic speciation study emphasizes the fact of similar reduction percentage of As (III), As (V) and total As in wet cooked rice when cooked with low-As containing water. The SAMOE value in 'risk thermometer' supports the higher risk of suffering from wet cooked rice (class 4) with increasing cooking water As concentration (class 3 to class 5).

Monsoonal paddy cultivation with phase-wise arsenic distribution in exposed and control sites of West Bengal, alongside its assimilation in rice grain.

The present study mainly deals with monsoonal paddy farming with respect to its phase-wise arsenic (As) accumulation and distribution throughout cultivation in As exposed sites and control areas of West Bengal for two consecutive years, 2017 and 2018. Arsenic uptake in paddy depends on the watering pattern with the help of groundwater (Madhusudhankati: 171 µg/l, Teghoria: 493 µg/l in Gaighata and Pingla: 10 µg/l in Medinipur), soil As phase-wise movement with its enrichment pattern and the variation of rainfall. Arsenic mobility is the highest in root and decreases with height of a plant. However, the synergistic effect of groundwater and rainwater makes a diffused approach to the nature of As flow in plants, because rainwater has a pivotal role in diluting the As content available for translocation. Reproductive phase accumulates maximum As compared to vegetative and ripening phases. Sequential extraction and SEM studies re-confirm no possibility of iron (Fe) plaque formation in root soils which sequestered As. Finally, we conclude that monsoonal cultivation provides least As enriched grain (exposed area: 350 µg/kg, control area: 224 µg/kg) irrespective of the variety of cultivar and area of cultivation, which amounts to one-third of pre-monsoonal grain (1120 µg/kg) and so, it is much safer for consumption with respect to As and micro-nutrient status.

Arsenic contamination in Kolkata metropolitan city: perspective of transportation of agricultural products from arsenic-endemic areas.

Arsenic exposure route for humans is through the drinking of contaminated water and intake of arsenic-contaminated foods, particularly in arsenic-exposed areas of Bengal delta. Transport of the arsenic-contaminated crops and vegetables grown using arsenic-contaminated groundwater and soil in arsenic-exposed areas to the uncontaminated sites and consequent dietary intakes leads to great threats for the population residing in non-endemic areas with respect to consumption of arsenic through drinking water. We have studied the food materials collected from 30 families and their dietary habits, apparently who consume arsenic-free drinking water as well as 9 well-known markets of Kolkata city. The total and inorganic arsenic intake has been estimated from the collected foodstuffs from the market basket survey (n = 93) and household survey (n = 139), respectively for human risk analysis. About 100% of the collected samples contained detectable amount of arsenic (range 24-324 µg/kg), since the origin of the food materials was somewhere from arsenic-endemic areas. The daily consumption of inorganic arsenic (iAs) from rice grain and vegetables for adult and children is 76 µg and 41.4 µg, respectively. Inorganic arsenic (mainly arsenite and arsenate) contributes approximately 88% of the total content of arsenic in vegetable. In most of the cases, insufficient nutrient intake by the studied population may lead to arsenic toxicity in the long run. An independent cancer risk assessment study on the same population indicates that the main risk of cancer might appear through the intake of arsenic-contaminated rice grain and cereals.

Arsenic accumulation in paddy plants at different phases of pre-monsoon cultivation.

Geogenic arsenic (As) contamination in Bengal Delta Plain is a growing environmental and research concern. Cultivation of staple crops like paddy on these contaminated fields is one of the major routes for human dietary exposure. The present study investigates changes of arsenic concentrations in paddy plant parts, root soil and surface soil throughout the various phases of pre-monsoon (boro) cultivation. Arsenic uptake property of paddy plants collected from 10 fields was found to be dependent on the variety of paddy plant (like Minikit, Jaya) rather than arsenic levels in groundwater (0.074-0.301 mg/l) or soil (25.3-60 mg/kg). Arsenic is translocated from root to aerial parts in descending order. Leaf, stem, root, root soil and surface soil showed a similar trend in their change of arsenic concentration throughout the cultivation period. Arsenic concentration was highest in vegetative phase; sharply declined in reproductive phase; followed by moderate increase in ripening phase. The young root tissues in vegetative (primary) phase could uptake arsenic at a much faster rate than the older tissues in later phases. With the growth of the plant, higher concentrations of iron in root soil in the reproductive phase confirmed the formation of iron plaques on the surface of the root, which sequester arsenic and prevented its uptake by plants. Finally, co-precipitation of arsenic with iron released from crystallized iron plaques results in loosening of the iron plaques from root surface. Thus, soil arsenic concentration increases in the final phase of cultivation which in turn contributes to increased concentration in plant parts.