Review
High levels of inorganic arsenic in rice in areas where arsenic-contaminated water is used for irrigation and cooking

https://doi.org/10.1016/j.scitotenv.2011.07.068Get rights and content

Abstract

Rice is the staple food for the people of arsenic endemic South (S) and South-East (SE) Asian countries. In this region, arsenic contaminated groundwater has been used not only for drinking and cooking purposes but also for rice cultivation during dry season. Irrigation of arsenic-contaminated groundwater for rice cultivation has resulted high deposition of arsenic in topsoil and uptake in rice grain posing a serious threat to the sustainable agriculture in this region. In addition, cooking rice with arsenic-contaminated water also increases arsenic burden in cooked rice. Inorganic arsenic is the main species of S and SE Asian rice (80 to 91% of the total arsenic), and the concentration of this toxic species is increased in cooked rice from inorganic arsenic-rich cooking water. The people of Bangladesh and West Bengal (India), the arsenic hot spots in the world, eat an average of 450 g rice a day. Therefore, in addition to drinking water, dietary intake of arsenic from rice is supposed to be another potential source of exposure, and to be a new disaster for the population of S and SE Asian countries. Arsenic speciation in raw and cooked rice, its bioavailability and the possible health hazard of inorganic arsenic in rice for the population of S and SE Asia have been discussed in this review.

Highlights

► Arsenic (As) deposition in paddy soil from irrigation water is a threat to the sustainable rice cultivation in South Asia. ► Cooking rice with arsenic-contaminated water increases its burden in cooked rice. ► Toxic inorganic As is the main species in Asian rice, and its content is increased in cooked rice from cooking water. ► As in rice is a potential source of exposure, and is supposed to be a new disaster for South Asia.

Introduction

Arsenic is the 20th abundant element in earth crust, and is ubiquitous in the environment (soil, water, air and in living matters) (Tamaki and Frankenberger, 1992). It has been well recognized that consumption of arsenic-contaminated foods leads to carcinogenesis (Mandal and Suzuki, 2002). Chronic effects of arsenic toxicity on humans have been reported from most of the countries in South (S) and South-East (SE) Asia through its widespread water and crop contamination (Kohnhorst, 2005, Mukherjee et al., 2006, Smedley, 2005). Arsenic contaminated groundwater is used not only for drinking purpose but also for crop irrigation, particularly for the paddy rice (Oryza sativa L.), in S and SE Asian countries (Meharg and Rahman, 2003, Ninno and Dorosh, 2001). In Bangladesh, arsenic-contaminated groundwater has been used extensively to irrigate paddy rice, particularly during the dry season, with 75% of the total cropped area given to rice cultivation (Meharg and Rahman, 2003). Background levels of arsenic in rice paddy soils range from 4 to 8 μg g−1 (Alam and Sattar, 2000, Williams et al., 2006), which can reach up to 83 μg g−1 in areas where the crop land has been irrigated with arsenic-contaminated groundwater (Williams et al., 2006). The problem of arsenic contamination in groundwater is not just restricted to Bangladesh. Other countries in S and SE Asia such as West Bengal (India), Vietnam, Thailand, Nepal and Taiwan have also been reported to have high levels of arsenic in groundwater (Dahal et al., 2008, Nordstrom, 2002) (Fig. 1). Paddy rice is the staple food for the people of these regions. Increasing levels of arsenic in agricultural soils from contaminated underground irrigation water, and its uptake in rice, vegetables, and other food crops (Meharg and Rahman, 2003, Williams et al., 2006) have become a real health emergency in this region. The presence of high levels of arsenic in rice is supposed to be a health disaster in South Asia (Meharg, 2004). Around 200 million people in S and SE Asia is supposed to be exposed to arsenic contamination from water and foods (Sun et al., 2006).

A large population in Asian arsenic endemic areas lives on subsistence diet of rice, a cereal which is grown mainly with groundwater contaminated by high level of arsenic. Therefore, rice contains relatively higher amount of arsenic, most of which is inorganic (Meharg et al., 2009, Sun et al., 2008, Torres-Escribano et al., 2008), compared to other agricultural products (Das et al., 2004, Schoof et al., 1999). The concentration of arsenic and its chemical forms in rice vary considerably depending on rice variety (Booth, 2008) and geographical variation (Booth, 2007, Meharg et al., 2009). The inorganic arsenic species dominates over organoarsenic species in both raw and cooked rice (Williams et al., 2005), which is accumulated/absorbed from paddy soil, irrigation water, and cooking water. Therefore, arsenic speciation in rice grain is influenced by its speciation in soil and water. In addition, the amount of arsenic absorbed by the cooked rice from cooking water and, the dietary intake of arsenic in human body are depended on the type of rice and the way the rice is cooked (Musaiger and D'Souza, 2008, Ohno et al., 2009, Rahman et al., 2006, Signes et al., 2008a, Signes et al., 2008b). Considering the high concentration of arsenic (mainly inorganic arsenic) in rice grain, cooking method, and high consumption rate, rice is revealed to be a major threat to health of the people of arsenic endemic S and SE Asian countries. In this review, arsenic speciation in rice, dietary intake, and health risk of inorganic arsenic species to the arsenic endemic and rice subsistent population of S and SE Asian countries have been discussed.

Section snippets

Arsenic in irrigation water: A threat to sustainable rice cultivation in S and SE Asia

The problem of arsenic contamination in groundwater is now well recognized in most of the S and SE Asian countries as discussed in the previous sections. Rice is the main cereal crop produced in this region, especially in Bangladesh and West Bengal (India), which is irrigated with groundwater during dry season. Recently, it has become apparent that arsenic-contaminated irrigation water is adding significant amount of arsenic in the topsoil and in rice, which pose serious threat to sustainable

Arsenic concentrations in raw rice

Up to date, significant number of articles on arsenic concentrations in rice and in its fractions have been published (Bae et al., 2002, Meharg, 2004, Mondal et al., 2010, Mondal and Polya, 2008, Rahman et al., 2006, Rahman et al., 2007a, Rahman et al., 2008a, Williams et al., 2006, Williams et al., 2005, Williams et al., 2007b). This implies that the dietary intake of arsenic form rice has been received much attention to understand the fat of arsenic exposure. Rice is by far the largest

Arsenic concentrations and speciation in cooked rice

The residents of arsenic contaminated areas of Bangladesh and West Bengal (India) depend mostly on rice for their daily caloric intake, and high arsenic concentration in rice indicates that rice is the major dietary source of arsenic for the population of this area (Mondal and Polya, 2008, Rahman et al., 2011). In South Asian countries, rice is usually cooked with a substantial amount of water. A number of studies reveal the influence of cooking methods on the retention of total and organic

Contribution of rice to dietary intake of arsenic

It has been proved that arsenic pollution poses a serious threat to human health. To minimize the health risks of arsenic toxicity, the main concern is to identify the sources of exposure to avoid the intake of this toxic element. Although there are many possible routes of arsenic exposure (Rahman et al., 2008a), the majors are inhalation (Pal et al., 2007), ingestion, and dermal contact (Mondal and Polya, 2008), of which ingestion is the largest contributor. Among the many possible pathways of

Bioavailability of arsenic from rice

The toxic inorganic arsenic species is readily assimilated into blood stream (Meharg and Rahman, 2003). Therefore, bioavailability and bioaccumulation of arsenic species from cooked rice are important for its intake in humans from this food source. Laparra et al. (2005) investigated the bioaccessibility and bioavailability of inorganic arsenic in cooked rice to assess the potential toxicological risk of this species. Results showed that the total arsenic concentrations in bioaccessible

Conclusion

Rice comprises the major part of daily diet of the population of S and SE Asian countries. Irrigation of arsenic-contaminated groundwater for rice cultivation has resulted high deposition of this toxic element in the top soil posing a serious threat to the sustainable rice farming in this region. Compared to other cereal crops, rice contains higher amount of arsenic most of which is toxic inorganic species. A number of studies reveal that, in addition to the drinking water, rice is another

Acknowledgment

The authors wish to thank the Japan Society for the Promotion of Science (JSPS) for financial support by Grants-in-Aid for Scientific Research (20·08343) in preparing this review paper. The reviewers are also acknowledged for their contribution in improving the quality and merit of the paper.

References (105)

  • A.A. Meharg

    Arsenic in rice — understanding a new disaster for South-East Asia

    Trends Plant Sci

    (2004)
  • A.A. Meharg et al.

    Inorganic arsenic levels in baby rice are of concern

    Environ Pollut

    (2008)
  • M. Misbahuddin

    Consumption of arsenic through cooked rice

    Lancet

    (2003)
  • D. Mondal et al.

    Rice is a major exposure route for arsenic in Chakdaha block, Nadia district, West Bengal, India: a probabilistic risk assessment

    Appl Geochem

    (2008)
  • K. Ohno et al.

    Arsenic intake via water and food by a population living in an arsenic-affected area of Bangladesh

    Sci Total Environ

    (2007)
  • J.S. Petrick et al.

    Monomethylarsonous acid (MMAIII) is more toxic than arsenite in Chang human hepatocytes

    Toxicol Appl Pharmacol

    (2000)
  • D. Postma et al.

    Arsenic in groundwater of the Red River floodplain, Vietnam: controlling geochemical processes and reactive transport modeling

    Geochim Cosmochim Acta

    (2007)
  • M.A. Rahman et al.

    Influence of cooking method on arsenic retention in cooked rice related to dietary exposure

    Sci Total Environ

    (2006)
  • M.A. Rahman et al.

    Accumulation of arsenic in tissues of rice plant (Oryza sativa L.) and its distribution in fractions of rice grain

    Chemosphere

    (2007)
  • M.A. Rahman et al.

    Accumulation of arsenic in tissues of rice plant (Oryza sativa L.) and its distribution in fractions of rice grain

    Chemosphere

    (2007)
  • M.A. Rahman et al.

    Cooking: effects on dietary exposure to arsenic from rice and vegetables

  • T. Roychowdhury et al.

    Survey of arsenic and other heavy metals in food composites and drinking water and estimation of dietary intake by the villagers from an arsenic-affected area of West Bengal, India

    Sci Total Environ

    (2003)
  • T. Roychowdhury et al.

    Survey of arsenic in food composites from an arsenic-affected area of West Bengal, India

    Food Chem Toxicol

    (2002)
  • R.A. Schoof et al.

    A market basket survey of inorganic arsenic in food

    Food Chem Toxicol

    (1999)
  • M.K. Sengupta et al.

    Arsenic burden of cooked rice: traditional and modern methods

    Food Chem Toxicol

    (2006)
  • G.X. Sun et al.

    Survey of arsenic and its speciation in rice products such as breakfast cereals, rice crackers and Japanese rice condiments

    Environ Int

    (2009)
  • J.S. Tsuji et al.

    Use of background inorganic arsenic exposures to provide perspective on risk assessment results

    Regul Toxicol Pharmacol

    (2007)
  • M.B. Alam et al.

    Assessment of arsenic contamination in soils and waters in some areas of Bangladesh

    Water Sci Technol

    (2000)
  • E. Bar-Ness et al.

    Short-term effects of rhizosphere microorganisms on Fe uptake from microbial siderophores by maize and oat

    Plant Physiol

    (1992)
  • P. Bhattacharya et al.

    Arsenic contamination in rice, wheat, pulses, and vegetables: a study in an arsenic affected area of West Bengal, India

    Water Air Soil Pollut

    (2010)
  • B. Booth

    Arsenic in U.S. rice varies by region

    Environ Sci Technol

    (2007)
  • B. Booth

    Arsenic speciation varies with type of rice

    Environ Sci Technol

    (2008)
  • B. Booth

    Cancer rates attributable to arsenic in rice vary globally

    Environ Sci Technol

    (2009)
  • A.M. Carey et al.

    Grain unloading of arsenic species in rice

    Plant Physiol

    (2010)
  • D. Crowley et al.

    Root-microbial effects on plant iron uptake from siderophores and phytosiderophores

    Plant Soil

    (1992)
  • D.E. Crowley et al.

    Mechanisms of iron acquisition from siderophores by microorganisms and plants

    Plant Soil

    (1991)
  • J. Dittmar et al.

    Arsenic in soil and irrigation water affects arsenic uptake by rice: complementary insights from field and pot studies

    Environ Sci Technol

    (2010)
  • J. Dittmar et al.

    Spatial distribution and temporal variability of arsenic in irrigated rice fields in Bangladesh. 2. Paddy soil

    Environ Sci Technol

    (2007)
  • J.M. Duxbury et al.

    Food chain aspects of arsenic contamination in Bangladesh: effects on quality and productivity of rice

    J Environ Sci Health A Toxic/Hazar Subs Environ Eng

    (2003)
  • J. Farmer et al.

    Assessment of occupational exposure to inorganic arsenic based on urinary concentrations and speciation of arsenic

    Br J Ind Med

    (1990)
  • J.K. Gurung et al.

    Geological and geochemical examination of arsenic contamination in groundwater in the Holocene Terai Basin, Nepal

    Environ Geol

    (2005)
  • H. Hasegawa et al.

    Effect of biodegradable chelating ligand on iron bioavailability and radish growth

    J Plant Nutr

    (2010)
  • D.T. Heitkemper et al.

    Determination of total and speciated arsenic in rice by ion chromatography and inductively coupled plasma mass spectrometry

    J Anal At Spectrom

    (2001)
  • Y. Hu et al.

    Sequestration of As by iron plaque on the roots of three rice (Oryza sativa L.) cultivars in a low-P soil with or without P fertilizer

    Environ Geochem Health

    (2005)
  • Y. Ishimaru et al.

    Rice plants take up iron as an Fe3+-phytosiderophore and as Fe2+

    Plant J

    (2006)
  • M. Islam et al.

    Assessment of arsenic in the water-soil-plant systems in Gangetic floodplains of Bangladesh

    Asian J Plant Sci

    (2004)
  • M.A. Khan et al.

    Fate of irrigation-water arsenic in rice soils of Bangladesh

    Plant Soil

    (2009)
  • M.A. Khan et al.

    Accumulation of arsenic in soil and rice under wetland condition in Bangladesh

    Plant Soil

    (2010)
  • M.A. Khan et al.

    Arsenic bioavailability to rice is elevated in Bangladeshi paddy soils

    Environ Sci Technol

    (2010)
  • A. Kohnhorst

    Arsenic in groundwater in selected countries in south and Southeast Asia: a review

    J Trop Med Paracitol

    (2005)
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