Silt from Christchurch earthquake harbours unknown dangers
Silt from liquefaction must be treated as if it has been contaminated with sewage, but authorities are unsure what other bugs it may be holding.
Health officials are urging the thousands of Christchurch residents and volunteers cleaning up the city to protect themselves, while the risk of gastroenteritis outbreaks are also looming.
Canterbury medical officer of health Ramon Pink said the enormous pressure underground had inevitably caused damage that had not yet been quantified.
"There's always the possibility that the liquefaction is contaminated."
As well as being contaminated with sewage, the silt could also be holding other contaminants – although health authorities did not know what these were.
The dust caused by the liquefaction was likely to irritate people with chronic illnesses such as asthma and anyone clearing it should wear a mask to avoid respiratory problems.
The Labour Department was working with rescue teams in the city centre to assess the risk of their exposure to asbestos, Dr Pink said.
Federated Farmers spokesman John Hartnell said farmers helping clear silt had welcomed a delivery of dust masks to wear as they worked, and that the silt was emitting a terrible smell in some places.
"It's treated as a toxic waste. It's a health hazard. That silt has certainly filtered all the toxins that come off the road."
Canterbury District Health Board said 120,000 tonnes of silt had been gathered by Monday night, and the original estimate of there being 180,000 tonnes was being revised upwards.
Pegasus Health senior clinical director Simon Winn Thomas said authorities were very worried about a gastroenteritis outbreak, but the move to chlorinate the city's water would help.
There had been 22 isolated cases of gastroenteritis, but it was a "matter of time" before that escalated because 40 per cent of households were still without water.
He feared an outbreak would hit a welfare centre and said although some cases of diarrhoea and vomiting had occurred at the centres, staff had been quick to isolate the people affected.
Dr Pink said it was crucial people kept heeding health messages such as boiling their water and using hand gels.
"You get filled with adrenaline and you follow what you are told to do and you do it but after a while you get a bit weary."
Dr Winn Thomas said GP practices were busy seeing people not only needing treatment for injuries suffered in the earthquake, but injuries suffered while cleaning up.
"They're cutting themselves on glass; putting their back out trying to get their bed out."
The quake had exacerbated the conditions of people with existing medical problems – some had lost their medicines or the stress and anxiety had made their condition worse.
The Dominion Post