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Survey of Dioxin Emission from PCP-treated Wood

3 Market analysis

• 3.1 Use of PCP as wood preservative in Denmark
• 3.2 Import and consumption of PCP in Europe
• 3.3 Import of PCP-treated wood to Denmark

The concern regarding use of PCP as wood preservative has focused on:

• The former use of PCP as a wood preservative in Denmark
• Current import of wood preserved with PCP

The essential experience regarding these to subjects has been examined through studies of existing Danish and international literature.

3.1 Use of PCP as wood preservative in Denmark

Up to 1977 PCP was widely used in Denmark for industrial wood preservation of windows and doors as well as for surface preservation and priming of wood before painting. The consumption in Denmark has been estimated as follows [COWIconsult, 1985]:

• Start in 1950 with around 25 tons PCP/year.
• Around 1960 consumption reached 100 tons PCP/year
• Maximum in 1972 with 250 - 300 tons PCP/year
• Decreased to 0 ton per year in 1978.

Of this consumption more than 90% was used for surface preservation of wood, whereas the rest was used for industrial wood preservation [COWIconsult, 1985]. Assuming that the consumption has developed linearly, the total accumulated consumption can be calculated to approx. 3,900 tons PCP. According to [Borsholt, 2003] PCP-based wood protection was dominating the market in the late 1960'es and the early 1970'es because of its very effective preservation of the wood. Almost all types of wood preservation used in this period contained PCP, irrespective of brand, coloured or non-coloured, industrial or private use. PCP was not used in indoor paints, as the PCP resulted in an obnoxious smell. Due to the health and environmental effects of the substance, the use of PCP decreased dramatically from the middle of the 1970'es [Borsholt, 2003].

There is no precise knowledge as to what extent PCP-preserved wood is still in use in Denmark. Assuming an average life of PCP-preserved wood of around 20 years, a minimum of 10 years, a maximum of 40 years and a linearly development, the amount of wood still in use in Denmark by year 2003 should equal an initial PCP quantity of approx. 430 tons.

An initial PCP quantity of 430 tons will assuming an average concentration for PCP of 3 % in wood preservatives and a density of the preservation liquids of 0,85 kg/l correspond to 16860000 liter of preservation liquids. Assuming, furthermore, a consumption of wood preservatives of 7m2/l, and an average thickness and density of the wood treated of approximately 2 cm and 520 kg/m³ respectively, the PCP quantity of 430 tons will correspond to around 1.230.000 tons of wood treated.

Based on data available in /WHO 1987/ and /Christmann et al. 1989 quoted in Jensen 1995/, the dioxin content in technical PCP commercially available in the seventies and the beginning of the eighties may be roughly estimated at 0.16 – 7 mg I-TEQ/kg PCP. Assuming that the dioxin content in the PCP used for wood preservation was in the range of 0.16 – 7 mg I-TEQ/kg PCP, 430 tons of PCP, furthermore, correspond to an amount of dioxin of 70 – 3000 g I-TEQ [Hansen and Hansen, 2003].

3.2 Import and consumption of PCP in Europe

Production of PCP and Na-PCP ceased in EU in 1992, and since then PCP and Na-PCP have been imported to the European market, primarily from USA and perhaps also from South East Asia. The European consumption of Na-PCP was in 1996 378 tonnes and of PCP 30 tonnes. The distribution of the 378 tons of Na-PCP was as follows:

Table 2.1: Consumption of Na-PCP in 1996, EU. [Borysiewicz and Kolsut, 2002]

Na-PCP is used for treatment of wood as a sap-stain control agent for freshly cut timber (preservation to avoid discolouring fungi). For industrial anti-sap-stain control a concentration of 2-5 % Na-PCP dissolved in water is used [Bywater, 2000 or Lassen, 2000]. Na-PCP is applied to the freshly sawn timber during the drying process. The preservation lasts 6 - 11 months [Kirk Othmer, 1993]. The consumption for this purpose covers almost 90 % of the total consumption of PCP, Na-PCP and PCP laurate. In Portugal three products are treated with Na-PCP: Pallet boards, construction timber and fencing panels [Borysiewicz and Kolsut, 2002].

Out of the 30 tonnes PCP imported in 1996 28 tonnes were synthesized to 46 tonnes PCP laurate in the UK. PCP laurate is used for preservation of textiles exposed to fungi and bacteria (tent textiles and military equipment). 15 tonnes of PCP laurate were used in the UK and France and the rest was exported to countries outside the EU. This means that no more than 2 tonnes of PCP can have been used for wood preservation in 1996 [Borysiewicz and Kolsut, 2002]. The import of PCP and Na-PCP to the EU has also been stated for 1999, and the development in import for 1996 and 1999 can be seen in table 2.2:

Table 2.2: Imports of PCP and Na-PCP to the European Union in 1996 and 1999. [Borysiewicz and Kolsut, 2002]

Production of PCP laurate in the EU ceased in 1999 according to the Commission Directive 1999/51/EC which prohibits the use of PCP and its compounds as a synthesizing agent in industrial processes from the 1 September 2000 [European Commission, 1999]. This means that the import of PCP probably is close to zero. It is however possible that a small amount is still imported for other uses, such as wood treatment [Borysiewicz and Kolsut, 2002]. Na-PCP is therefore the most used substance.

3.3 Import of PCP-treated wood to Denmark

The amount of PCP-treated wood that is imported to Denmark is unknown, but it must be assumed that a part of the PCP-treated wood from Southern Europe will be imported to Denmark, e.g. via disposable pallet boards arriving with different types of goods. The consumers cannot see if the disposable pallet boards are treated with PCP, and this means that the pallet boards easily can be disposed of in a wrong way, e.g. by using the wood as fuel in for example private wood-burning stoves.

Pallet board is regarded to be the most likely source of import of PCP-treated wood, but import of other PCP-treated wood products from countries outside the EU is also possible. The following studies report of PCP contents in other types of wood from countries outside the EU, but it is not known if wood with such conditions have been imported to Denmark.

In a Swiss investigation from 1996 PCP and TeCP was measured in 47 samples of different kinds of wood. 9.3 % of the total amount of samples contained more than 5 mg/kg of PCP + TeCP together. PCP and TeCP were found in different kinds of wood from Finland, Canada and Africa. 30 % of the samples with tropical wood from Africa contained more than 5 mg/kg of PCP+TeCP [OFEFP, 1998].

Until a few years ago PCP was also used in Malaysia for anti-sap-stain control/preservation of the exotic wood species called hevea or rubber wood. The PCP is typically applied when the timber is freshly sawn and still wet. This means that the absorbency of the wood is rather low and that some of the PCP will be removed again during the processing. The use of PCP is now illegal in Malaysia, but it is questionable if the ban has been fully implemented at present [Witterseh, 2003] and [Henriksen, 2003]. Countries like Indonesia, Phillippines and Cambodia which also produce large amounts of hevea might also be using PCP preservation of wood and are perhaps still using it [Henriksen, 2003].

The Danish Technological Institute (Teknologisk Institut) has in a project for The Danish Environmental Protection Agency in the autumn of 2003 analysed for chemical substances in different types of tropical wood. The PCP content in hevea has been examined, but the tests showed no signs of PCP-content in the samples [Witterseh, 2003].

The implementation of the FSC marking and the focus on the environmental effects of tropical wood must also influence the amount of PCP-preserved tropical wood imported to Denmark, and it is generally believed that the amount of PCP-treated tropical wood imported to Denmark is very low. It may however be possible that small amounts of PCP-treated tropical wood is imported to Denmark due to the large quantities that is imported in the present years from Asia and Africa.

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Version 1.0 Juli 2004, © Danish Environmental Protection Agency