Though it is well known that ingesting high levels of arsenic from contaminated groundwater in India has been linked to a range of ailments, a recent peer-reviewed study suggests that even low levels of arsenic consumption may impact cognitive function in children, adolescents, and young adults.
The research study, which is part of a bigger investigation into how a range of environmental and biological factors affect neurological and cognitive development in young people, also found that those exposed to arsenic had reduced grey matter (brain tissue that is vital to cognitive functions) and weaker connections within key regions of the brain that enable concentration, switching between tasks, and temporary storage of information.
‘Silent pandemic’
“Chronic exposure to arsenic could be creating a ‘silent pandemic’ affecting large portions of the global population,” say the authors in the study published in the latest issue of the peer-reviewed journal, JAMA Network Open.
For their research, the scientists linked the urine samples (to estimate arsenic exposure), performance in a battery of computerised tests (that evaluate cognitive function) and brain-images (that picturise various regions of the brain) of 1,014 participants from five regions across India.
Poor affected most
Arsenic exposure, previous studies have shown, is particularly harmful to the poor. This study too, reinforced the fact that the economic and nutritionally poor face greater cognitive impairment from arsenic exposure. However, a scientist associated with the study told The Hindu that the impact of arsenic in impairing cognition at an individual level was “limited”. The effect was more pronounced when individuals were considered as part of a collective, the scientist said.
However, the authors note in their study that deficits in cognitive tasks could point to “…adverse consequences at a population level, contributing to an overall increase in school failures, diminished economic productivity, and increased risk of criminal and antisocial behaviour.”
Mapping brains
“We didn’t set out to investigate the link between arsenic exposure and brain function…it emerged from the C-Veda data. Going ahead, we’d like to more thoroughly investigate the degree to which arsenic affects the brain. We’re also looking at the role of a host of other environmental factors, in separate studies, such as air pollution,” Nilakshi Vaidya, clinical psychologist and lead author of the study, told The Hindu in a phone conversation.
C-Veda (Consortium on Vulnerability to Externalizing Disorders and Addictions) is an India-United Kingdom research initiative, spanning several universities. It aims to evaluate the effect of risk – whether biological and environmental – on cognitive development and also compare these effects across people in industrialising (India) and industrialised (United Kingdom) societies.
This also includes mapping the brains of those participating in the study and thereby evaluating and comparing neurological development.
Arsenic in rice
For participants in the study, exposure to arsenic was strongly linked to food intake, indicating that background inorganic and organic arsenic in foods is a major contributor to arsenic exposure in many parts of India beyond those regions where arsenic exposure from groundwater is naturally known to be high. West Bengal, Jharkhand, Bihar, Uttar Pradesh, Assam and Manipur have long been identified as regions with high background arsenic levels.
“Arsenic intake from food was most commonly correlated with rice intake, which is more commonly consumed in south India (Rishi Valley and Bangalore) and where the highest mean arsenic levels were observed,” the authors noted. “Importantly, arsenic exposure may be an easily modifiable risk factor: while treatment of water is possible but complicated and costly, cooking rice in a certain way removes the naturally occurring arsenic in brown rice by over 50% and in white rice by 74%, while not reducing micronutrients in the rice.”
Since the 1990s, both the Central and State governments in Bihar and West Bengal have sought to address arsenic contamination. A common strategy employed is to encourage piped water access rather than groundwater extraction, install arsenic removal plants and – if groundwater extraction is inevitable – encourage extraction from aquifers (water channels below the ground) that are deeper than 100 m, instead of shallower aquifers, which generally contain higher amounts of arsenic.
