September 1 sees the first direct impact of the changes to the system of approvals for wood preservatives in the UK brought in under the European Biocidal Products Directive (BPD).

In 2000, preservatives on the UK market approved under the UK’s own legislation (Control of Pesticides Regulations) could continue to be sold and used in the UK until September 1 this year under BPD rules. However, new information on the safety of their active ingredient(s) had to be submitted if manufacturers wanted to continue to supply those preservatives beyond that date.

Preservatives containing arsenic compounds (CCA types) are already subject to restrictions introduced from July 2004 under different EU legislation. The reduced market for CCA meant that manufacturers could not justify the cost of developing the new safety information for arsenic required by the BPD and, consequently, approval for CCA in the UK will be withdrawn on September 1. This is expected to happen throughout the EU wherever CCA was approved before. It is important to remember that this does not affect CCA-treated timber already in the supply chain at that time (although the rules on where treated timber can be used must be followed) or already in use.

Copper-chrome products

Preservatives from the copper-chrome ‘family’ that includes CCA, but from which arsenic was removed or replaced by other compounds, have been used widely in the UK, especially since the CCA restrictions were introduced. Examples are copper-chrome (CC – sometimes based on oxides of copper and chromium and called CCO); CCB (with boron) and CCP (with phosphate). Their advantage is that they can be used in the same treatment plant previously used for CCA with little or no modification. It is likely they will also have to be withdrawn on the same date as CCA.

The BPD rules require information to be submitted on each active ingredient. In the case of chromium compounds, however, their function in the formulation has long been regarded by industry scientists as a fixative for other compounds. Fixation by chromium was the key to the very long durability imparted by treatment with copper compounds; the supreme example is CCA where chromium is effective in fixing both copper and arsenic. If this role of chromium could be established under the BPD rules then the copper-chrome family of preservatives could continue to be supplied in the UK (and elsewhere in the EU where they were already approved under national legislation) after the September 1 deadline.

This has been the subject of intense debate with the Health & Safety Executive (HSE). One of the difficulties is that existing UK approvals of chromium-

containing preservatives show chromium as an active ingredient on the label. This has not mattered before but differences of opinion within Europe as to whether chromium compounds can be accepted as fixatives rather than active ingredients have made a decision difficult.

However, the HSE recently published its position and, based on existing label statements and tests that show chromium compounds do have some level of activity against wood-rotting fungi, they have concluded that preservatives from the copper-chrome ‘family’ must be withdrawn from the market by the September deadline.

However, differences of opinion within Europe continue to make the situation uncertain. It is understood that the European Commission is seeking a common position to be applied in all EU markets and that this position could differ from the one adopted so far by the HSE. A common position is essential, otherwise it is conceivable that chromium-containing preservatives could continue to be used in Germany, for example, but not in the UK.

The continuing uncertainty may not be resolved quickly, so it is still expected that the HSE will withdraw approvals for copper-chrome type preservatives on September 1.

WPA’s role

Members of the Wood Protection Association (WPA) who supply copper-chrome type preservatives are advising their customers individually about their options for change. These include the new range of highly effective copper-organic and microemulsion preservatives which are already approved and established in the market.

The WPA and its members are working with the HSE to ensure an orderly transition, including procedures for managing stocks of copper-chrome preservatives after September 1. As mentioned, wood already treated with a copper-chrome type preservative is not affected and can continue to be sold and used in accordance with existing practice.

Further information, including detailed guidance on the CCA restrictions, is available from the WPA. Visit www.wood-protection.org