Arsenic and Water Safety

Here is a new study that may turn out to be one of the most important of the year.

Tens of millions on people around the world, most particularly in Bangladesh, are forced to drink water containing dangerously high amounts of arsenic. The very same stuff that has been used by countless poisoners.

The classic symptoms of arsenic poisoning are:

• Headache
• Abdominal pains
• Vomiting
• Difficulty breathing
• Light headedness
• Delirium
• Neuropathy
• Stroke
• Skin lesions: usually thickening of the skin of the palms and soles with wart-like excresences
• Reduced production of red and white blood cells
• Increased risk of cancers of the lung, skin, bladder, liver, kidney and prostate
• Death

The exact pattern of symptoms depends on the acuity of the exposure, the amount of arsenic to which a person is exposed and the individual’s own makeup.

The new research – published this week in the journal Science – is from Rice University’s Centre for Biological and Environmental Nanotechnology in Texas, and it may give us a quick and cheap way of getting most of the arsenic out of drinking water. The investigators used minute particles of iron oxide – very similar to common rust – to bind large amounts of arsenic. The iron oxide particles are really tiny: just 12 nanometres (billionths of a metre) across, about 5,000 times smaller than the width of a human hair. When mixed into contaminated water, the tiny crystals became coated with the poison and began behaving like iron filings. The iron oxide/arsenic combination can then be removed from water using a simple hand-held magnet.

One of the investigators, Professor Doug Natelson had this to say, "The idea of using magnetic particles to filter and clean water is not particularly new. The trick here is that these particles are very, very small, which means they’re essentially all surface. So the arsenic sticks to the surface of the particles, and what we’ve found is that when the nanoparticles are in the right range of sizes, you can pull them out of solution with a relatively small magnetic field gradient that you could get from, say, a permanent magnet."

As an additional refinement, the scientists needed to develop a technology that would be usable in one of the poorest parts of the world. In one experiment flakes of rust were made into nanoparticles by heating them in coconut or olive oil at 350C. They could then be used in water purification.

This is excellent news, and if confirmed, it could save hundreds of thousands if not millions of livees, and unspeakably awful chronic ill health.