27 August 2007:
If the pond life goes star-shaped, you’d be wise not to
drink the water.
Researchers from CRC CARE are pioneering a world-first
technology to warn people if their local water or air is
contaminated with dangerous levels of toxic heavy metals and
metal-like substances.
Mr. Andrew McKay, PhD student of CRC CARE and the University of
Queensland is studying the changes that take place in a unique
water microbe when it is exposed to arsenic, cadmium and lead
– industrial and natural contaminants around the world.
“Our goal is to develop a simple field test that can warn
people or environmental authorities if dangerous levels of toxic
metals or metalloids (metal-like substances such as arsenic) are
present in the environment, to which they might be exposed,”
he explains.
The test could provide vital in helping to tackle one of the
world’s greatest disasters – the poisoning of tens of
millions of people in Bangladesh and West Bengal, India, through
naturally–occurring arsenic in their household well
water.
“But countries such as Australia and New Zealand also have
an arsenic problem from the tens of thousands of old sheep and
cattle dips where arsenic was used for decades to control
pests. In many cases these old dip sites have been forgotten
and spreading urbanization has covered them.
“We also have numerous old gold mining sites where arsenic
was once used, tailings dumps from almost any kind of metal mine
and wetlands that were used to trap contaminated runoff.”
Old factories which produced paint or batteries have left
historical residues of lead in our inner city areas, while
fertilizer plants and other industrial processes have deposited
cadmium and other toxic metals.
“If toxic metals are present in the soil there is
always a risk they will leach into drinking water, get into our
food chain and reach infants and children.
“As city land value increase due to demand, we need better
ways to make sure the land is clean and safe to live and work
on,” Andrew says.
He reports good progress in developing water organisms as an
early warning tool for such contamination, especially where a mix
of toxic contaminants is involved.
“We’ve found a number of readily-observable changes
which take place in the organism when it is exposed to increased
levels of toxic metals and metalloids – their growth and
reproduction rates slow down, their shape changes – becoming
star- or v-shaped.
“And of course, at high levels of the toxins, they
die.”
These changes will enable scientists to use the pond creatures
as living sensors – or biosensors – for toxic metal
contamination.
The current research challenge, he says, is to use the organisms
to develop a sensitive enough test to discern whether or not the
level of contamination poses a risk to human health and life.
Simple pond creatures are often more tolerant of metals than
humans, who accumulate the toxins over a much longer period
of time, leading to cancers, immune system breakdown, nerve or
brain damage or other forms of poisoning.
The research task now is to equate the symptoms observed in the
microbes with levels of risk to humans and animals, and to package
this as a cheap, simple test that can provide a quick answer in the
field – rather than through long and expensive laboratory
testing, Andrew says.
