This is a final version submitted for publication. Minor editorial changes may have subsequently been made.
THEY'RE panicking in Indiana, US. When TV news show 13 Investigates tested the surface of picnic tables there recently, it found high levels of arsenic.
Now, thousands of picnic tables are being removed from parks or painted with an oil-based stain.
The picnic tables are made of timber treated with copper chrome arsenate (CCA), used in most of Australia's park picnic tables.
Should we also be panicking?
Scientists have demonstrated that arsenic leaks out of CCA-treated timber, even 20 years after it has been treated. It is also known that exposure to arsenic can cause cancer.
According to the World Health Organisation, arsenic is a known carcinogen and is acutely toxic. It can cause lung, bladder and skin cancer, as well as reproductive and neurological problems. But is there enough arsenic in Australian picnic tables to cause such dire consequences?
We don't really know because no one has done wipe tests. Without such data, and given the high levels of arsenic found by such studies overseas, can we be complacent about the risks involved?
Some nations have taken a precautionary approach. CCA-treated timber has been banned altogether in Switzerland, Vietnam and Indonesia and severely restricted in Japan and Europe.
In 2005 the Australian Pesticides and Veterinary Medicines Authority cancelled the use of CCA for treating timber destined for garden furniture, picnic tables, exterior seating, children's play equipment, patio and domestic decking and handrails.
But should we be worried about the picnic tables (and play equipment) already out there in our parks and on our beaches?
Should our councils be allowing parents and children to eat food off treated timber picnic tables that could be coated in arsenic?
People can be exposed to arsenic through touching CCA-treated timber because surface arsenic sticks to human skin. It then can be transferred to the mouth, for example by subsequent handling of food.
It also can be transferred to the mouth by eating food placed directly on CCA-treated surfaces.
Yet how many people think twice about eating off council picnic tables? Surely that is what they are there for?
The APVMA claims it has no power to control how people use the structures made from CCA-treated timber. It is local councils that control the ongoing use of existing picnic tables. Local councils may be comforted by the fact that picnic tables have been around for many years and no one has yet set out to prove that they got cancer from them.
But who would dream that their lung or bladder or skin cancer might have been caused by eating off picnic tables in their youth? Especially given that Australian authorities didn't admit to the potential problem until recently.
The lack of past lawsuits will not provide comfort to the wider community. Perhaps only tests showing picnic tables are arsenic-free will do that.
Otherwise there might be good reason to follow Indiana park authorities and do something about all those picnic tables.