Refinement of arsenic attributable health risks in rural Pakistan using population specific dietary intake values

Background: Previous risk assessment studies have often utilised generic consumption or intake values when evaluating ingestion exposure pathways. If these values do not accurately reflect the country or scenario in question, the resulting risk assessment will not provide a meaningful representation of cancer risks in that particular country/scenario. Objectives: This study sought to determine water and food intake parameters for one region in South Asia, rural Pakistan, and assess the role population specific intake parameters play in cancer risk assessment. Methods: A questionnaire was developed to collect data on sociodemographic features and 24-hour water and food consumption patterns from a rural community. The impact of dietary differences on cancer susceptibility linked to arsenic exposure was evaluated by calculating cancer risks using the data collected in the current study against standard water and food intake levels for the USA, Europe and Asia. A probabilistic cancer risk was performed for each set of intake values of this study. Results: Average daily total water intake based on drinking direct plain water and indirect water from food and beverages was found to be 3.5 L day-1 (95% CI: 3.38, 3.57) exceeding the US Environmental Protection Agency’s default (2.5 L day-1) and World Health Organization’s recommended intake value (2 L day-1). Average daily rice intake (469 g day-1) was found to be lower than in India and Bangladesh whereas wheat intake (402 g day−1) was higher than intake reported for USA, Europe and Asian sub-regions. Consequently, arsenic-associated cumulative cancer risks determined for daily water intake was found to be 17 in children of 3-6 years (95% CI: 0.0014, 0.0017), 14 in children of age 6-16 years (95% CI: 0.001, 0.0011) and 6 in adults of 16-67 years (95% CI: 0.0006, 0.0006) in a population size of 10000. This is higher than the risks estimated using the US Environmental Protection Agency and World Health Organization’s default recommended water intake levels. Rice intake data showed early life cumulative cancer risks of 15 in 10000 for children of 3-6 years (95% CI: 0.0012, 0.0015), 14 in children of 6-16 years (95% CI: 0.0011, 0.0014) and later life risk of 8 in adults (95% CI: 0.0008, 0.0008) in a population of 10000. This is lower than cancer risks in countries with higher rice intake and elevated arsenic levels (Bangladesh and India). Cumulative cancer risk from arsenic exposure showed the relative risk contribution from total water to be51%, from rice to be44% and wheat intake 5%. Conclusions: The study demonstrates the need to use population specific dietary information for risk assessment and risk management studies. Probabilistic risk assessment concluded the importance of dietary intake in estimating cancer risk, along with arsenic concentrations in water or food and age of exposed rural population

Effect of liberalized U.S.-Mexico rice trade: A spatial, multiproduct equilibrium analysis

A spatial, multiproduct equilibrium model featuring United States-Mexico long-grain rice trade is developed to determine the effect of removing Mexico's rice tariffs in 2003 on U.S. rough and milled rice exports to that country. Analysis considers rice milling costs and yields in the United States and Mexico, transportation costs associated with U.S. rice exports to Mexico, mill by-product prices in Mexico and the United States and the changing tariff levels. Results show Mexico's graduated decline in rice tariffs over the 1997 to 2003 period to increase U.S. rice exports to Mexico about 1% per year or a total of 7% over the 6-year period. United States' long-grain rice price and production is modestly affected by the increased exports, while the impact on Mexico's rice production and price is comparatively large. Further, results show the historic incentive to export rough rice to Mexico will be replaced by an incentive to export milled rice, thus opportunities for the U.S. rice milling industry to form alliances with Mexican packers and increase direct relationships with large retailers in Mexico. [EconLit citations:C61, Q17, and R40.] © 2003 Wiley Periodicals, Inc. Agribusiness 19: 1-17, 2003.