Food@Manchester


The deadly secret of a staple diet

An interview with Dave Polya

Smoking kills.

For a long time, that was a pretty contentious statement.

Today, we have dire government health warnings printed in large letters on every packet of cigarettes (usually accompanied by a grisly photo of a pair of diseased lungs or blocked arteries, just in case we didn’t get the message first time).

But it wasn’t until after many years of published research linking smoking with lung cancer, that it was universally accepted that the link existed.

It may seem strange, but there’s a connection between what happened in the tobacco industry to what’s happening right now in the cultivation and consumption of one of our staple foods, rice.

Unfortunately, the way it’s grown, rice is very susceptible to absorbing arsenic, particularly in areas like Bangladesh and west Bengal, India, where there are huge numbers of paddy fields and rice is eaten every day by most of its residents.

Over many years, rain and snow has carried sediments containing naturally occurring arsenic down from the Himalayas and into the River Ganges

Over many years, rain and snow has carried sediments containing naturally occurring arsenic down from the Himalayas and into the River Ganges, where it has been deposited in large sedimentary wedges and is contaminating the groundwater - in increasingly higher concentrations.

As a result, a typical concentration of arsenic in rice in these areas could range from anything from 20 to 900 parts per billion. At the high end, this exposes people who eat it regularly to levels that would never be permitted within a drinking water supply.

Over the past ten years we have starting to see more and more research linking regular exposure to arsenic in drinking water supplies with a range of potentially fatal illnesses, including cancers of the lung, bladder and skin and heart disease.

Given the dependence of some of the areas most affected on this staple food, the implications of any mitigating actions will clearly have huge implications.

Now some of our most recent research conducted here at the University of Manchester, in collaboration with colleagues in India and Bangladesh, is revealing that there is a clear correlation between the amount of arsenic that people ingest through eating rice and the kind of cell damage we associate with cancer.

Not all global rice supplies are affected, but possibly as much as 15 per cent could be contaminated with potentially life-threatening levels of arsenic.

So far, however, the weight of that evidence has not yet been sufficient to force governments or rice producers to take action.

Given the dependence of some of the areas most affected on this staple food, the implications of any mitigating actions will clearly have huge implications.

But it’s clear that rice has the potential to be just as deadly as smoking.

I can only hope that this time, it doesn’t take decades for governments and food producers to accept it.


Dave Polya is Professor of Environmental Geochemistry in the School of Earth, Atmospheric and Environmental Sciences. A 30 year veteran of the University of Manchester, his current research is focused on the study of arsenic in groundwater in Bengal and Southeast Asia and its implications for the local and wider populations.

Q & A

What is your specific field of research?

30 years ago, I had an interest in how the world worked and particularly the role that water played in controlling the composition of sediments and the formation of ore deposits. We use the same techniques today but the focus has shifted more to the study of environmental problems, such as the concentrations of arsenic in groundwater used as a supply for drinking water in many parts of the world.

Why is the University of Manchester the right place for your research?

I came to Manchester because it had one the best geology departments in the world. If anything that reputation has even further enhanced. We’ve changed quite a lot in 30 years… we still have some “old school” geologists but our main focus is on things like planetary geology, atmospheric physics and chemistry, microbiology and petroleum engineering. It’s a much broader school than it used to be. In terms of what I’m involved with now, this university is playing a leading role in the development of the research, even though we started five years or so after other groups began their work.

How important is collaboration?

Collaboration is critical to what we do. By and large it’s a community that’s very happy to collaborate and because ultimately there’s a human focus to this work, people are very willing to share things and be supportive. Here’s an example… we recently put in a research proposal and noticed at the last minute that there was a requirement to have signed letters of support. We sent out 20 emails to people in Europe, US and China late that night and by 7am the next morning, we had eight letters of support. That says a lot about how supportive this community is.

Why is food such an important issue at this point in time?

It’s a fundamental issue - we can’t survive without it. Increases in our population and in individual wealth have given us a challenge to ensure we have enough resource to live our lives sustainably. On top of this, it seems that one of the foods that people depend on in some of the most populous and impoverished areas of the world - rice - may be creating additional health concerns.

How does your research help meet this challenge?

Unfortunately, the way it’s grown, rice is very susceptible to absorbing arsenic. Our research has shown that a significant amount of rice - possibly as much as 15 per cent globally - is not safe to eat and is a particularly large risk for people in central and southeast Asia where people can eat as much as 500g of rice a day. Our research has shown that there is a link between the amount of arsenic people ingest in these areas and the damage of cells in their bodies. When we looked at groups that had eaten rice containing more than 300 parts per billion of arsenic, the greater the likelihood of the genetic material in their cells breaking up in to micronuclei, a development with proven links to cancer and other complications. The levels of arsenic present in rice in these would never be accepted in drinking water - I believe rice should be subject to the same testing and regulatory restrictions.

Looking ahead, what are you most excited about?

There’s a big potential for research to make a major contribution and help people live healthier, longer lives - that’s pretty exciting! And I think we’ve got technology on our side too. The technical capabilities that we have today are far greater than they were when I began my career 30 years ago. The analytical equipment is far more advanced and computing power has vastly increased too which means we can do a lot more with the data.

And what are you most concerned about?

We have evidence accumulated over the last 10-15 years that a high concentration of arsenic in rice is not a good thing. My worry is that there was increasing evidence about the damage to health caused by smoking, but it took a very long time before laws were put in place to counter this. I think we will have to come up with a sustainable solution to the problem before we are able to convince governments to change.

By Bill Bows in interview with Dave Polya.