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SESSION 2 - Inter-relationships of Arsenic, Soil, Food, Water and Health

SESSION 2 - Inter-relationships of Arsenic, Soil, Food, Water and Health

(1) Factors affecting arsenic accumulation and speciation in rice

Meharg AA, Williams PN, Ademoko E, Solaiman AR, Feldmann J, Raab A
A.meharg@abdn.ac.uk

Presentation

Rice generally has grain arsenic levels about 10 fold higher than other grains, and in this dietary staple of SE Asia, inorganic arsenic levels in rice make a major contribution to human arsenic intake. As the paddy fields of Bangladesh and West Bengal are widely irrigated with arsenic contaminated groundwaters, the factors affecting grain accumulation and speciation in rice were investigated. A detailed field survey of Bangladesh revealed that there is considerable spatial, temporal and plant physiological control on rice accumulation and speciation in grain. This is due to strong spatial patterns of arsenic loadings in irrigated paddy fields, strong spatial patterns in arsenic bioavailability within paddies, and a strong relationship between arsenic levels in the shoot and grain export. Comparison of arsenic uptake with that of wheat and barley proves that rice is highly susceptible to arsenic accumulation with a shoot/soil transfer factor of around 1, more than 10 fold higher than for other grain crops. This is probably due to rice being anaerobically cultivated, which greatly alters arsenic dynamics in soil solution.

(2) Arsenic Accumulation In Irrigated Paddy Soils And Possible Mitigation Methods

Hugh Brammer

Presentation and supplement

Abstract Irrigation with arsenic-contaminated groundwater is adding arsenic to soils in Bangladesh, India and some other countries in south and south-east Asia. The added arsenic gradually accumulates in the topsoil, and amounts now appear to be reaching levels toxic to rice in some soils that have been irrigated with highly-contaminated water for 10-20 years or more. Arsenic accumulations vary considerably between and within tubewell command areas. Practical mitigation and rehabilitation methods will vary from place to place according to local environmental, economic and cultural conditions, and many may be costly to apply. Possible methods include: water treatment; providing an alternative safe water supply; substituting alternative farming methods and soil treatments to reduce arsenic uptake by crops; and removing contaminated topsoils.

(3) Monte Carlo Based Quantification of Increased arsenic-related cancer risk due to rice intake in West Bengal, India.

Ms Debapriya Mondal, Postgraduate Researcher, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, U.K.
debapriya.mondal@postgrad.manchester.ac.uk

Dr Dave Polya, Senior Lecturer, School of Earth, Atmospheric and Environmental Sciences. University of Manchester, U.K.
David.polya@manchester.ac.uk

The importance or otherwise of rice as an exposure route of arsenic for people living in Bengal and other areas impacted by hazardous arsenic bearing groundwaters is currently in dispute. We use combined field, laboratory and computational methods to quantitatively estimate the overall increased cancer risk due to ingestion of arsenic-bearing rice in adults in two typical arsenic impacted districts in West Bengal. The distribution of chronic daily intakes (CDI) of arsenic in the study group has been estimated by Monte Carlo simulation following fitting of probability curves to measured distributions of arsenic concentration in rice, rice ingestion rates; and body weight. Estimated target cancer risks for an exposure duration of 10 years were then calculated using the USEPA (1989) one hit model. The mean increased life-time cancer risk, over and above that due to uptake of arsenic from drinking water, was 4.5 x 10-4, higher than the 10-4 to 10-6 range typically used by the USEPA to guide determination of regulatory values. Furthermore, about 5 % of the cancer risks calculated were greater than 10-3. On-going work is focused on determining the nature of particular sub-groups of the population that may have significantly higher cancer risks than the mean.

(4) Evaluation of human exposure to inorganic arsenic in populations of northern Argentina

Calatayud, M.,1 Devesa, V.,1 De Bovi-Mitre, G., 2 Farias, S., 3 Gimenez, M. 4 Villaamil, E. 5
1 Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC), Apdo 73, 46100 - Burjassot, Valencia, Spain. E-mail: vdevesa@iata.cis.es
2 Facultad de Ingeniería - Universidad Nacional de Jujuy - Gorriti 237, San Salvador de Jujuy, Provincia de Jujuy, Argentina.
3 Comisión Nacional de Energía Atómica (CNEA), Gerencia de Tecnología y Medio Ambiente, Av. Gral. Paz. 1499 (B1650KNA) San Martín, Provincia de Buenos Aires, Argentina.
4 Cátedra de Química Analítica. Facultad de Agroindustrias. Universidad Nacional del Nordeste, Argentina.
5 Cátedra de Toxicología y Química Legal. Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina.

Argentina is one of the Latin American countries with the highest environmental arsenic concentrations. It has been estimated that over one million inhabitants, fundamentally in rural areas, depend on groundwater with arsenic concentrations in excess of 50 µg/L. One of the most affected areas is located on the Chaco-Pampean Plain, in the northern part of the country, where for over 20 years the population has shown symptoms of chronic endemic arsenicism. The present study evaluates human exposure to inorganic arsenic in populations of two provinces in the mentioned geographic setting: El Chaco and Santiago del Estero. An assessment has been made of the ingestion of inorganic arsenic through drinking water and raw and cooked foods in several families. The duplicate rations method has been used for food sampling. The results obtained - the first of their kind in Argentina - indicate ingestion far above the toxicological reference value recommended by the FAO/WHO (ISTP = 15 µg inorganic arsenic/kg body weight /week). This implies a serious public health problem in the region. Urgent implantation of the opportune palliative measures by the national authorities is thus required.

Acknowledgments: The authors are indebted to projects CYTED 105PI0272 and AECI A/4883/06 for the help received in conducting the present study.

(5) Suffering for water, Suffering from water: Gendered and Classed dimensions of Arsenic Poisoning in Bangladesh

Dr. Farhana Sultana Lecturer, King's College London
farhana@jonosc.com

Presentation

The arsenic crisis in Bangladesh poses a significant water management challenge in the country, in that it involves not only complexities of water provision and water management institutions, but also involves interlinked health issues and social implications. Paying attention to gender and class issues in water access, use and control highlights how the arsenic poisoning of drinking water affects various groups of society differently. In this paper, I bring forth the various ways by which rural Bangladeshis are simultaneously suffering for water, as well as suffering from water. An explicit attention to gender and class issues is needed to notice and reveal such issues, which may not always be apparent or captured otherwise, thereby highlighting the importance of focusing on the multi-layered and interconnected social, economic, cultural and political dynamics involved. Such a perspective of highlighting the social implications are often drowned out by the over-emphasis on technocratic solutions and need greater attention from researchers, policy-makers, and project implementers.