August 06, 2007
Is there a chemist in the house?
When Abbas offered me the keys to the liquor cabinet here, he asked that I write about science -- which was just as well, because I don't know about anything else. I barely know anything about science, either, but perhaps what distinguishes science from other pursuits is exactly that: the average practitioner's willingness to be overwhelmingly honest about what they know, and how tenuous a grasp they have on even that little knowledge. When I look around at science writing, a lot of it seems to pander to my earliest ideas about science: namely, that science is a place to go for answers. Good science writing also tells about how the answers were found, and really good science writing gives a sense of how secure (or otherwise) those answers may be, but for all that the emphasis is on answers. To me, and I think to most working scientists, that's largely backwards -- because science as practiced is mostly about questions.
So for this month's column and the next, I thought I would just do some thinking in public, about a problem that has come to my attention. Not all problems are scientific in nature, that is, amenable to a solely scientific solution; but the methods and cast of thought that we associate with science can bring information to bear on at least some aspects of most problems. Science seems to me to be necessary but not sufficient for the solution of most of the important problems facing our species.
Background: Chemists Without Borders
Thank you for an excellent article regarding carbohydrate vaccines (C&EN, Aug. 9, page 31). On page 35, John B. Robbins is quoted as saying that Salmonella typhi is "the best typhoid vaccine that's ever been made ... vaccines don't make much money. The Vi conjugate vaccine is so revolutionary, and typhoid is such a common and serious disease around the world, but no manufacturer in the U.S. or Europe is interested in it." Is this still true? If so, shame on us. What stand will the American Chemical Society take to catalyze implementation of such a vaccine?
Could this be our "Chemists Without Frontiers," à la "Médicins Sans Frontières?"
Bego and co-founders Steve Chambreau and Lacy Brent are not the first to decide that doctors should not be the only profession without borders. There are also Laywers, Teachers, Sociologists, Builders, Engineers, Clowns and I daresay a good many other Professions Without Borders. All of them seek to do, within their own fields of expertise, something roughly on par with the mission of MSF. So really, the name of the organization largely explains what CWB are about:
Chemists Without Borders is a public benefit, non-profit, international humanitarian organization designed to alleviate human suffering through the use of proven chemical technologies and related skills. Our primary goals include, but are not limited to, providing affordable medicines and vaccines to those who need them most, supplying clean water in developing countries, facilitating sustainable energy technologies, and supporting chemistry education.
I became aware of CWB through their commitment to Open Chemistry, and then by taking part in their conference call series I learned about their interest in groundwater arsenic remediation, which is the problem I want to think about here.
The Problem: Groundwater Arsenic
Element number 33 in the periodic table, arsenic (As) is a greyish metalloid solid at room temperature. It's a common constituent of the earth's crust, and is readily leached into groundwater from a variety of minerals. It's tasteless and odorless -- and it's both toxic and carcinogenic. The effects of chronic arsenic poisoning are complex and interact strongly with genetic and environmental factors, and (especially in the case of cancers) usually take at least 10-15 years to manifest. Symptoms include pigment changes, hyperkeratosis and cancerous lesions of the skin, cancer of the lungs, kidneys, liver, prostate and urinary bladder, peripheral vascular degeneration (which may lead to gangrene), peripheral neurophathy (which may include partial paralysis), anemia and leukopenia. In addition, arsenic is a teratogen, and chronic exposure of a population can lead to increased incidence of spontaneous abortion and congenital malformations.
The World Health Organization Guidelines for Drinking Water Quality include a provisional target of 0.01mg/l for safe drinking water. By this criterion, and even by the earlier WHO target of 0.05 mg/l, there are dangerously contaminated groundwater sources in, inter alia, Argentina, Bangladesh, Chile, China, India, Mexico, Thailand and the USA (recent review here). Of these risk areas, Bangladesh has attracted particular attention, not only because of very high arsenic levels in parts of the groundwater supply but because widespread reliance on this water supply, and the concomitant public health disaster, appears to be the direct result of overseas aid:
In the 1970s, international agencies headed by the United Nations Children's Fund (UNICEF) began pumping millions of dollars of aid money into Bangladesh for tubewells to provide clean drinking water. According to the World Health Organization, the direct result has been the biggest outbreak of mass poisoning in history. Up to half the country's tubewells, now estimated to number 10 million, are poisoned.
Tubewells are narrow bore, drilled, pump-operated wells designed to access relatively shallow aquifers; millions of these wells were dug as a response to the region's abnormally high infant mortality rate, much of which was attributed to microbial contamination of surface water.
In 2000, the WHO estimated that between 35 and 77 million of Bangladesh's 125 million inhabitants were at risk from arsenic-laden water. A 2003 paper estimated that current contamination levels could be expected to cause "600,000 cases of keratosis, 125,000 cases of skin cancer, and 3000 fatalities per year from internal cancers", and in 2004 further studies demonstrated that a large proportion of groundwater supplies throughout the Ganga-Meghna-Brahmaputra Plain may be contaminated, putting at risk a total population of well over 450 million. These numbers put the Asian arsenic crisis at the head of any list of public health disasters, dwarfing Bhopal or Chernobyl.
Tune in next time
In keeping with my claim that scientists tend to be overwhelmingly honest, I will now confess that not only have I run out of time, I have not finished reading for the rest of this article. Already, however, one can see a number of questions to which various sciences can perhaps provide answers:
- Geology, chemistry: where does the As come from? How much of it is there, and where is it going?
- Chemistry: how can As be removed from water supplies?
- Biology: is there a better way to remove As?
- Chemistry, biology: would it be better to return to surface water supplies and deal with waterborne disease in other ways?
- Sociology: how do we get the actual people affected to adopt and maintain various solutions?
Next month, I'll do my best to find answers to these, and whatever other questions occur to me along the way. As always, please use the comments to let me know what I've missed or got wrong.
This work is licensed under a Creative Commons Attribution 3.0 License.
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