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Factory workers and builders handling treated timber are suffering health effects from solvents and other substances used to protect the wood.
Skin reactions, rashes, headaches, bleeding noses and other symptoms are dogging builders and workers in pre-framing factories who are forced to handle wood treated with light organic solvent preservatives (LOSP).
The workers have complained to industry bodies and the timber could be banned if the issue is not resolved.
Kevin Hing, executive officer of the Timber Preservation Council, said complaints about handling the wood were coming more from frame and truss plants, where workers were indoors, than from workers at outdoor building sites.
But the wood was not the problem, he said. Rather, extreme pressure was being put on wood treatment plants to keep pace with demand from the frenetic building sector and plants were being asked to turn around orders faster.
Instead of allowing the chemicals to evaporate from the wood over some days, some plants were dispatching the wood before the airing process was completed, he said.
Pieter Burghout, chief executive of the Registered Master Builders Federation, said hundreds of builders and workers in wall and frame factories had suffered since the wood became common in 2004. LOSP wood is used in most of the 25,000 or so houses built annually, he said.
Ashley Hartley, the federation's president, said he had been concerned about LOSP wood since 2004.
"I'm aware of people who have had nose bleeds, headaches, but they didn't know what caused it. They were found to have been using LOSP timber with a huge amount of solvents in it. I know people wondering why they were coming out in rashes on their hands and forearms."
Master Builders is calling for the wood to be banned because of the health hazards.
"Let's get rid of it and instead put out timber that's not going to cause issues," Mr Hartley said.
The federation and the council have both issued warning guidelines on working with LOSP wood, treated with a white spirits-based preservative. Both organisations said workers should avoid working with the timber in confined spaces. They should wear goggles when cutting the wood and a face mask to avoid dust inhalation. Work clothes should be washed separately and hands washed after touching the wood. People should avoid eating, drinking, smoking or putting their hands near their mouth after working with the timber and the wood must never be used on BBQs.
They also warn against using the wood for beehives or when it comes into contact with drinking water. Nor should the wood be used for toys or in kitchens as counter tops or cutting boards.
The council is telling timber treatment plants and the sector that the wood must be stacked and exposed to the air in a well-ventilated area for at least four days before being handled and wrapped ready for the building site. If these guidelines are adhered to, the council says there should be no problems.
Mr Hing said some people had complained of headaches after handling the LOSP timber which had not been correctly aired but the treatment process itself was not to blame.
"It's the market conditions," he said.
He heard of one case where a delivery driver was told to pick up wood being treated with LOSP on the same day it was delivered to the treatment plant, instead of allowing the minimum four days for the chemicals to evaporate.
Plants were being forced to get the wood out to pre-nail frame and truss plants or sites so fast that some were not allowing the chemicals to evaporate, he said.
Occupational Safety and Health said solvents from LOSP timber can "give off gas for some time after the treatment".
It issued a publication warning of dermatitis and delayed onset burns from handling the timber and advised people to wear gloves when handling the wood.
Solvent to blame for headaches
Martin Goulden, a Wellington builder, said he had worked with the chemically treated timber and developed problems, including headaches.
"I've noticed it particularly working in confined spaces like a roof," he said, saying the timber smelled of solvents.
He is now cautious around the wood and said he had no problems as long as he was working in well-ventilated areas.
He also believes chemicals should be dried off the timber well before the materials reached his sites.
The 48-year-old said: "You have to be mindful of a few things with it. If it's been recently treated and packaged up and hasn't had an opportunity to dry it has a very strong odour."
He said he wasn't overly worried about possible long-term health effects, but said he would like to see more information and research about the effects of the treated timber on health. "That really has to come from manufacturers."
Mr Goulden, who has been a builder for 30 years, said he wasn't worried about the health of his wife and four children.
"They are not in contact with it."
He said he hoped there were no long-term health effects.
"But you don't really know what's around the corner do you?
"I haven't got a crystal ball. I don't know what the long-term issues are but you would hope that the manufacturers in conjunction with Occupational Safety and Health would have a responsible attitude."
He said there would be no harm in increasing people's awareness about the effects of the treated timber and how to handle it.
