Government agency won't ban arsenic-treated timber

2.00pm - By KENT ATKINSON

The Government's watchdog on hazardous substances says it cannot ban arsenic-treated wood from being used on children's play equipment and homeowners' decks, even though the United States is stopping its use.

The Environmental Risk Management Authority (Erma) announced today that before it could ban copper chromium arsenic (CCA) as a timber treatment, legally it would have to trigger a reassessment of the chemical.

"Currently there is not sufficient evidence to demonstrate that the health risks associated with the current population's exposure to CCA-treated timber warrant the substance being reassessed," Erma said today.

Instead, it proposes "prudent measures" to limit voluntary exposure to CCA and further investigation "into any environmental and occupational risks associated with the use of CCA".

The US Environmental Protection Agency (EPA) will from next January cancel the registration of arsenic treatments for wood used in most residential settings -- including play equipment, decks, picnic tables, landscaping, residential fencing and walkways.

The US consumer products safety commission is also assessing the health risk to children associated with arsenic-treated timber.

Erma said CCA had not been comprehensively assessed because it was an existing chemical grandfathered into the new regulatory regime under the Hazardous Substances and New Organisms Act 1996 (HSNO).

Different classes of chemicals have been slowly phased in to the new rules for hazardous substances, with explosives first, then dangerous goods and toxic substances.

Pesticides were scheduled to be phased in from June 2003 but Erma has just announced that the transfer of all groups of pesticides -- including CCA and other timber treatment chemicals -- to the HSNO has now been deferred to July 1 next year.

The announcement by Erma, a quasi judicial authority, that it will not be banning arsenic-treated wood was made today on the release of a report Erma commissioned from public health consultant Dr Deborah Read.

"One of the reasons for commissioning the Read report was to see whether a re-assessment would be justified on the basis of public health effects," Erma said in a statement." The conclusion is that a re-assessment would be difficult to justify."

Arsenic, both manufactured and naturally occurring, can cause cancer and nerve, stomach, intestine and skin problems. Small levels can be contracted by touching treated wood or contaminated soil but there is conflicting data on the quantities required to affect humans.

The EPA began reviewing the risks from wood preservatives in 1978 and six years later issued worker protection guidelines, and requiring consumer warning labels on timber containing arsenic.

But a report by University of North Carolina scientist Rick Maas, which concluded that regular direct contact with CCA-treated timber was "a national health priority", prompted the EPA and timber companies to phase out by December 2003 wood deck and playset uses of arsenic-based preservative.

Erma said it only became aware of the Maas report in November 2002, and decided to investigate public health issues arising from the use of CCA-treated timber.

"The principal conclusion is that the extent of any risks arising from CCA remains unclear, and that the Maas report has not in itself altered that situation," Erma said today.

"An additional factor to consider is that there are a variety of other sources, both natural and otherwise, for arsenic in the environment".

Erma apparently became aware of the Maas report after a Wellington newspaper employed scientists to test soil from local playgrounds that used CCA timber. They found arsenic levels of up to 300mg/kg -- 10 times over Environment Ministry guidelines.

Since the Maas report, the US Consumer Products Safety Commission has reported arsenic exposure can lead to lung and bladder cancers.

The commission said toddlers who routinely put their hands in their mouths were ingesting significant quantities of arsenic when they used playground equipment made of arsenic-treated wood. Similar problems arise from arsenic-treated house decks.

A child's exposure varies according to how often and for how long they played on arsenic-treated timber, the amount of arsenic on their hands, and the amount of that which they swallowed.

The US report said the lag time between exposure to arsenic and cancer arising in a person could be decades, but the increased cancer risk would range from about two extra cases per million people to 100 extra cases.

The agency said not every exposed individual would get cancer, but to minimise the risk of exposure, children's hands should be washed with soap and water immediately after outdoor play and before eating.

Erma said Dr Read's report did not indicate information which would significantly alter pre-1996 assessments of the risks posed by CCA, and that the HSNO Act "does not currently provide for the breadth of action that might be needed to deal effectively with CCA".

It said the Government was expected to develop a strategy for improving the workability of the hazardous substance elements of the Act, so reassessment of CCA "remains a longer term possibility".

In the meantime, the current Building Industry Authority (BIA) review of treated and untreated timber in buildings "will determine the future use of CCA treated timber in playgrounds, decks and domestic structures".

The BIA is expected to issue a discussion paper in June, with an eight-week public consultation period, and Erma said it would then review public submissions before taking further action.

Erma did not believe there was enough evidence to take action on existing decks, playgrounds and other facilities, but schools and councils might wish to take a precautionary approach.

The Read report had dealt only with public health risks, and investigations should also be made of possible environmental and occupational effects, particularly on timber treatment workers and builders, Erma said.

The timber industry should be monitored to see how well it was following codes and guidelines on safe wood treatment.

There should also be investigation of availability of alternatives to CCA, their technical and economic feasibility, as well as practical limitations on dealing with existing CCA timber structures.

Erma was discussing with the Government how this further work should be done, with regulatory action under the HSNO Act still an eventual possibility.

Arsenic facts:

* CCA is intended to protect wood from dry rot, fungi, moulds and other pests.

* Arsenic slowly leaches from CCA-treated wood, and some chemicals may also be dislodged from the surface of the wood upon contact with the skin, particularly on newly treated timber.

* Arsenic causes cancer in humans and is acutely toxic, but exists naturally in the environment in relatively low concentrations.

* Erma says it is inadvisable to use CCA timber where contact with food or animal feed can occur -- including cutting boards, counter tops, beehives, or containers for compost or mulch -- or where animals can chew on treated wood.

* Erma has not recommended that people replace existing decks or play equipment made with CCA-treated wood.

* People can regularly apply penetrating coatings to treated wood, such as oil-based, semi-transparent stains, to reduce the migration of chemicals. But film-forming stains such as latex semi-transparent, and opaque stains, and oil-based opaque stains may peel and flake. Coatings that make playground equipment more slippery should also be avoided.

* Timber treated with alternative preservatives is available.

* Homeowners should never burn CCA-treated wood but dispose of it at council landfills.

* From January 2003, United States regulators will not allow CCA timber to be used for most residential structures.

* From June 2004, the European Commission will partially ban use of CCA-treated timber, except where skin contact by the public is unlikely, and CCA timber will not be used in new residential construction.


- NZPA