Scientists have found that discarded cigarette ash can cheaply and easily remove more than 96 percent of poisonous arsenic from water.
As a result of mining and other industries, the toxin arsenic has contaminated groundwater at high levels in countries such as China, Chile, Hungary and Mexico. The poison is odourless and tasteless so it's hard to detect, but it can cause skin discolouration, stomach pain, partial paralysis and a range of other serious health problems.
Technology already exists to help eliminate arsenic from water, but it's expensive and requires a high level of expertise, which makes it impractical for use in rural and developing regions.
Scientists have already started trying to use natural waste materials, such as banana peels, to clean up arsenic, but so far most projects have proved ineffective.
A team of researchers, led by Jiaxing Li from the North China Electrical Power University in Beijing, decided to investigate whether porous cigarette ash might do a better job.
The scientists coated cigarette ash in aluminium oxide, a simple, one-step method, and then tested it on contaminated ground water. They found the material removed more than 96 percent of the arsenic, reducing it to a safe level according to the World Health Organisation standards.
Because cigarette ash is already being thrown away around the world each day, this is an extremely cost-effective solution to the public health issue, the scientists report in the American Chemical Society's Industrial & Engineering Chemistry Research journal, where they published their results.
So now scientists could clean up cigarette butts and arsenic in developing countries at the same time, which is pretty awesome.