Radiata pine (Pinus radiata) is the mostly widely grown plantation pine in the world - prized for its timber and pulp. Ironically it's under extreme threat in the few remaining wild stands of California through loss of habitat and a virulent fungal disease. In New Zealand, it's the mainstay of our expansive forestry industry with around 1.6m hectares, 40% of total global coverage, to be found growing here - it's even sometimes referred to as 'New Zealand pine'. Today it's widely used for building housing, for posts and poles in agricultural, marine and horticultural industries as well as for outdoor furniture, decks and handrails.
The problem with this fast-growing 'wonder timber' is a vulnerability to attack from fungi and insects. So we impregnate it with a cocktail of chemicals - copper, chromium and arsenic or 'CCA'. CCA-treated timber comes in six grades from H1 for internal use through to H6 for marine use in pilings of structures built in water. New Zealand has been a pioneer of CCA timber treatment since the 1930s and today we are reputedly the highest per capita users of it in the world. However it's not so popular in the EU, Japan and Indonesia where use is now banned or in the USA where it has been voluntarily withdrawn by industry.
As of 2012, the Australian Pesticides and Veterinary Medicines Authority tightened restrictions on CCA, stating that: 'It cannot be used on high-contact timber structures: this includes garden furniture, picnic tables, exterior seating, children's play equipment, patio and domestic decking, and handrails.' One of several concerns is exposure to arsenic and a potential link with cancer.
Dr. Bruce Graham who provides technical advice to NZ government and United Nations agencies and has written several reports on CCA treated timber, points out that "Traces of arsenic are present on the surface of treated timber, concentrations are worse in the early stages after treatment and timber will go on losing arsenic over years."
Referring to overseas countries turning away from CCA-treated timber he explains: "Many decisions are based on a precautionary approach taking into account assessments of the carcinogenic effects of arsenic, risks to children from treated timber used in play equipment, and possible environmental impacts."
According to Graham, young children are the most at risk "simply because of their 'hand-mouth' behavior... Adults know to wash their hands before eating but a child playing on a deck with a lolly is likely to drop it and then put it straight back into its mouth."
Members of the building industry are also at risk. "People should be wearing masks and gloves when cutting or working the timber and you don't want sawdust blowing across the garden."
Environmental concerns also include air pollution. According to Graham, burning CCA wood releases 90% of the arsenic in the smoke and about 10% remains concentrated in the ash. "There are regular prosecutions of small-scale waste management contractors found burning treated timber and councils are pro-active in pursuing infringers. Yet during the winter months in some parts of the country, according to the Clean Air Society of Australia and NZ, we exceed by more than double national air quality guidelines for arsenic in our atmosphere."
Instead of the enforced restrictions implemented overseas, we have confusing or absent guidance from our government agencies. The Environmental Protection Authority states: "CCA treated wood has been in use for many years without discernible health effects."
Search the Department of Health or any of our 20 District Health Boards for public health guidance on CCA and you'll find none. The Ministry of Education does consider CCA "a potential health risk" and recommends building new playgrounds with alternative materials and sealing any CCA-treated wood playground equipment less than six months old.
CCA-treated timber is commonly used in New Zealand playgrounds.
However many regional councils still use CCA-treated timber on children's public play facilities with no current policy to do otherwise. ?Moves away from CCA have been considered. In 2003 a committee representing quasi government and industry groups (including Building Industry Authority, MacDonald's and NZ Plunkett Organisation) considered adopting a new standard that would ban all uses of CCA-treated timber. The proposal was rejected.
As Graham points out: "In New Zealand the building industry is based around CCA and alternatives are more expensive. To suddenly say you can't use CCA any more would be another political whipping post."
ALTERNATIVES
The cost of substituting the CCA-treated component in a timber-framed and clad house costing $500K would be about $500 according to Dan Gudsell of Abodo Wood. Gudsell specialises in supplying low-toxicity exterior timbers. In spite of this, he says getting hold of alternatives is not so easy. "You'll be hard-pushed to walk into any timber merchant and find decking and exterior, structural timber that's not CCA treated."
There are alternative treatments like Copper MicroPro where more copper is used in place of arsenic but it's early days. As for whether the days of CCA in NZ are numbered, Graham is measured: "We may give up on the use of CCA treated timber in the future but I don't see it happening for the moment."
He speculates that exposure overseas of our tolerance of CCA could provide the leverage needed for change. "Certainly as long as we push the 'clean green' image internationally we have got several vulnerabilities and this would be one of them."
