Arsenic risk highest in water and rice
by Kelly Stone
Researching the severity of arsenic contamination in Bangladesh and how it impacts on human lives is a personal passion for PhD graduate and Bangladeshi academic Nasreen Islam Khan.
Khan, who graduated with her PhD at UniSA’s graduations in August, returned to her home-country of Bangladesh during her thesis to assess the extent of arsenic exposure to humans through water and food intake.
"In Bangladesh, much of the rural population relies on groundwater as the principle source of both drinking and irrigation water," she said.
"Unfortunately, this water is also contaminated to a large extent with arsenic which leaches into the groundwater from natural mineral sources. The arsenic contamination is a natural phenomenon which poses a considerable risk to the rural population."
Health effects from arsenic ingestion range from skin pigmentation to cancer. Arsenic is ingested mainly through drinking water, but also by consuming rice as the rice plants uptake arsenic through the roots to the grain. Rice is a staple food in Bangladesh and large amounts can be consumed up to three times a day by villagers.
Khan found that the health risk varied significantly between individuals, even from within the same household, with children and the elderly being most susceptible.
"Overall, the estimated risk was significantly higher than acceptable guideline levels," she said.
"In fact, 43 per cent of the surveyed population were exposed to arsenic levels higher than acceptable guideline levels in their drinking water on a daily basis.
"Arsenic contaminated drinking water was the major contributor (58 per cent) towards the total lifetime arsenic carcinogenic risk, with cooked rice being the second highest contributor (41 per cent) and contribution from vegetables and other foods being almost negligible (less than 1 per cent)."
Khan’s research across 18 rural villages developed mapping and predictive tools to identify potential areas within the landscape that had higher human health risks related to dietary intake of arsenic. The basic methodology could be applied to any contaminant and was not specific to arsenic, she said.
She said her study was one of the first conducted where dietary exposure of arsenic and risk assessment was conducted on an individual basis and where geo-spatial models were developed for quantifying and identifying the variability of human health risk in the rural landscape.
"This research has great public benefit in providing government agencies and planners with a tool capable of mapping and predicting risk associated with dietary intake of contaminants," she said.
"On a social level, as a Bangladeshi native, I was attracted to this area of research because it gave me the opportunity to apply my skills to an issue that would be of benefit to my country.
"I hope this information can be used to assist in the management of arsenic issues in Bangladesh."
Khan’s research was completed under the supervision of Associate Professor David Bruce and Dr Gary Owens in the Centre for Environmental Risk Assessment and Remediation (CERAR) in collaboration with Dhaka Community Hospital (DCH), Bangladesh; Massachusetts Institute of Technology (MIT) and Environmental System Research Institute (ESRI), USA; and the School of Population Health, Queensland University.
Prior to completing her PhD at UniSA, Khan had a first class Honours and Masters degree in Geography from the Jahangirnagar University in Bangladesh, and also undertook postgraduate study in Applied Geomorphology and Engineering Geology at ITC in the Netherlands to complete a second Masters degree. She is also an Assistant Professor at the University of Dhaka, Bangladesh.
Khan has already secured a postdoctoral position in a prestigious research institute in Europe, where she will continue her arsenic research.