Grey-green wood treated with chromium copper arsenic (CCA) is common in New Zealand. But how many people know that pollution, associated health risks and toxic waste make the transition to a circular bioeconomy difficult?
Other countries, including Australia, the US, and the EU, have phased out or restricted the use of CCAs, switched to safer alternatives, and established appropriate end-of-life disposal options.
Heavy metals in OCA include copper, chromium, and arsenic. They do not decompose or break down when burned, like organic compounds.
Heavy metals leach from wood, polluting soil and water. When CCA-treated wood is burned, most of the arsenic evaporates and pollutes the air, while chromium and copper contaminate the ash.
The World Health Organization (WHO) lists arsenic as one of the ten chemicals that pose the greatest risk to public health. It is a confirmed carcinogen. Chrome and copper are also unsafe for health.
Prohibited or restricted elsewhere
In the early 2000s, the U.S. Environmental Protection Agency and the timber industry agreed to limit the use of CCA-treated wood to industrial use. This was driven by concerns about human exposure to arsenic from playground equipment, decks, picnic tables, and other uses.
Most other developed countries continued to operate with similar restrictions. CCA is no longer registered in the EU as a wood preservative.
However, CCA still dominates the New Zealand processed wood market. It is widely used in playgrounds and residential buildings with a high risk of human exposure. And this despite the fact that Standards New Zealand agreed to a more favorable alternative.
The New Zealand Environment Authority has also recommended building playgrounds with alternative materials, placing consumer information in stores, and more widely disseminating preventive health advice. But this recommendation was ignored in New Zealand for two decades.
The standards jointly developed by Standards Australia and Standards New Zealand have not yet been approved by stakeholders. The standard includes a consumer safety data sheet stating that CCA treated wood cannot be used for products that come into direct contact with food, garden furniture, outdoor seating, children's play equipment, decking and floors, and hand towels.
It also describes the correct method of disposal and indicates the correct handling measures:
avoid sawing
wear a dust mask, gloves and goggles
washing hands and face after working with wood treated with CCA.
New Zealand has excluded environmental risks from ACC safety assessments. But the environmental risk is the main reason for the seizure of HCP abroad.
There are several national examples of CCA environmental pollution.
Arsenic concentrations in winter air exceed New Zealand ambient air quality standards. This is caused by improper burning of CCA treated wood in fireplaces and burning in the agricultural sector.
Arsenic concentrations are believed to exceed drinking water standards in the slow-draining Marlborough aquifer.
Although soil contamination is localized around CCA-treated wood, these hot spots can occur frequently. Vineyards, for example, have 500-600 poles per hectare. Land use changes for urban development will require significant land reclamation.
Improper disposal of ashes from wood burners into green bins results in arsenic contamination of the compost. Intentional composting of treated wood has also been found.
In a 35-country study, New Zealand was the only country where indoor dust arsenic contamination exceeded the non-carcinogenic risk index for children.
no safe delete
CCA is also an obstacle to a circular bioeconomy. The reuse of wood is an established procedure. Prioritize reuse over use of heat (use it as a fuel to use its energy).
However, there is no suitable reuse of wood waste treated with CCA. The problem is even bigger. CCA treated wood cannot be separated from untreated wood during waste crushing.
In New Zealand, CCA treated wood must be disposed of in a safe landfill, leaving future generations to deal with toxic CCA leachate. Burning at a suitable facility is the only viable method of disposing of CCA treated wood; In Germany, this is a mandatory deletion option. However, there are no major incinerators in New Zealand.
A quick visit to any school, playground, picnic area, garden or home improvement store reveals New Zealand's relatively relaxed attitude towards CCA. The government and industry state that they have never burned CCA-treated wood, but this is not made known to the public.
Recent suggestions at my local home improvement store include "yes, this is the standard for playground equipment" and "it can be incinerated or recycled." Reclaimed wood is often sold as lumber. At my last check, three of the 50 lumber listings on the TradeMe auction site were CCA treated lumber.
New Zealand's industrial approach failed. The first step in resolving the CCA liability issue is simple as alternative preservatives are allowed. Restricting the use of CCA treated wood or introducing product protection schemes will add nothing to New Zealand's CCA heritage.
Making sure our children don't inherit the legacy of the existing CCA is harder. We need to run a real incinerator.
CCA-treated wood is cheaper than safer alternatives, but only if the costs of disposal are passed on to future generations.
This article is reprinted from The Conversation under a Creative Commons license. Read the original article. 
Quote : Despite bans elsewhere, New Zealand still uses wood preservatives linked to arsenic pollution (March 1, 2023). arsenic.html
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