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

Risk Assessment of Ingestion of Arsenic-Contaminated Water among Adults in Bandlaguda, India

Background. The Indian Government describes the Patancheru Industrial Development Area (IDA) near Hyderabad as a heavily polluted site. Previous studies show levels of arsenic in ground and surface water that exceed the national drinking water standard. Objectives. We conducted a pilot study to characterize potential non-cancer and cancer risks associated with ingesting arsenic-contaminated water by adult residents of Bandlaguda, a village in the Patancheru IDA. Methods. We used United States Environmental Protection Agency (USEPA) equations to calculate hazard quotients (for non-cancer outcomes) and excess cancer risks. Inputs included information on water sources and consumption that we collected from a representative sample of residents using a standardized questionnaire, and arsenic concentration data from a previous study. We calculated point estimates of risk and used @RISK software to conduct probabilistic simulations and perform sensitivity analyses. Results. In both the point and probabilistic analyses, the mean hazard quotients exceeded 1 for both men and women, indicating potentially elevated risk of non-cancer outcomes. Mean lifetime excess cancer risks using the USEPA default 70-year life expectancy were 0.01 (i.e., 1 in 100) for men and 0.006 (i.e., 6 in 1,000) for women. Mean excess risks using Indian life expectancies were 0.01 for men and 0.007 for women. Sensitivity analyses identified the reference dose and cancer slope factor as the most influential input variables. Conclusions. Our results show that arsenic in water consumed by Bandlaguda adults may be associated with both non-cancer and cancer risks. There is an urgent need to identify unsafe sources of drinking water in this community and educate residents on the hazards of using them