Mushrooms could clear up poisons in soil

By SIMON COLLINS

Modern-day alchemists have found a group of "magic mushrooms" that transform poisonous chemicals into fertile soil that can be laid safely on farms.

Waikato University biologist Professor Roberta Farrell says some native New Zealand white rot fungi can reduce dioxins and pentachlorophenol (PCP) in contaminated soils by more than 90 per cent.

The fungi, now being trialled on 50 tonnes of contaminated soil at Kinleith, offer an apparent solution for more than 100 sites nationwide that have been sealed off because of chemical contamination from past timber treatment.

A medical study of 62 former sawmill workers in 2001 found that PCP was a probable cause of health problems in about a third of them. Many had breathing difficulties, their clothes rotted and their bodies stank.

The co-ordinator of Whakatane group Sawmill Workers Against Poisons (Swap), Joe Harawira, said the affected workers had been waiting "a long, long time" for a way to clean up the poisoned sites.

"I'm so pleased that, if it is successful, nature is doing the job for us," he said.

Putaruru farmer Gordon Stephenson, who represents the Royal Forest and Bird Protection Society on a consultative group for the Kinleith trial, said finding a fungus to clean up PCP was "an extraordinary development".

The new fungus technology will be exploited commercially by a joint-venture company, bioRemedi, owned a third each by Waikato University, timber company Carter Holt Harvey and US consulting firm EarthFax.

Professor Farrell, who came to New Zealand in 1995, previously worked for an American biotechnology company on using fungi to treat wood. She has tested New Zealand fungi for the past two years looking for ones that break down poisons.

EarthFax helped with the engineering techniques required to grow the fungus on wood chips for a month and then insert it into piles of contaminated soil.

"It's a bit like making bread," Dr Farrell said. "First you get your starter for four weeks, then you mix with soil - roughly one part wood chips to nine parts soil.

"You make that into a mound, like earth composting, and let the fungus and the fungal enzymes work on the PCPs and dioxins."

Dr Farrell said the PCP-eating varieties of white rot fungi could completely rehabilitate poisoned soil.

A co-author of the medical study of ex-sawmill workers in 2001, Auckland professor of medicine Des Gorman, said further research was still needed to prove the suspected link between PCP exposure and health problems.

The 2001 study of 62 workers identified by the Wood Industries Union found that many suffered from breathing difficulties, fever, headaches, eye irritations, skin diseases and dirty and foul-smelling sweat.

More than a third developed mental problems such as anxiety, depression, confusion, tiredness and sleeplessness. Fifteen had symptoms of chronic fatigue syndrome.

PCPs were banned in New Zealand in 1991. The Health Research Council is about to let a $520,000 research contract for a comprehensive two-year study into the effects of PCPs on workers who were exposed to them in the 50 years up to 1991.

The council has told researchers that timber companies cannot keep the workers' records indefinitely. "An immediate start to the research project is therefore desirable."