A hazardous substance
Produced through the distillation of tar from coal, creosote is used to protect wood against termites, fungi, mites and other pests. Allowed only for industrial applications, creosote is commonly used to treat railway sleepers and other outdoor installations such as utility poles. Creosote contains polyaromatic hydrocarbons, including benzo(a)pyrene, which is classified by the International Agency for Research on Cancer as a Group 1 carcinogen.
Heavy duty industrial wood constructions such as utility poles and railway sleepers are predominantly impregnated with creosote, a residue from coke production. However, due to the high polyaromatic content in creosote, it is classified as a carcinogenic substance. Several of the polycyclic aromatic hydrocarbons (PAHs) found in creosote are considered persistent, bioaccumulative, and toxic, potentially having long-lasting effects on the environment.
“Due to its hazardous properties, creosote has been identified as a biocidal substance that should be substituted,” notes Ana Cura, Nynas Regional Director for Western Europe. “Considering the importance of long-lasting wood constructions for infrastructure, the European Commission has continued to authorise the use of creosote in some applications.”
Since 30 April 2023, creosote may only be used in wood treatment of railway sleepers and utility poles for electricity and telecommunication in those countries where the need of these articles has been assessed to be greater than the risks of using them.
As a result of the new EU restriction and a widespread expectation that creosote will eventually be entirely banned, wood treatment producers are working on alternatives. One such solution is based on naphthenic oil acting as carrier of active components that meet the European Union’s Biocidal Product Regulation (BPR) requirements.
“Thanks to their great solvent power, our NYTEX grades are an attractive choice for formulators,” says Anna Eriksson, Nynas Technical Manager Chemical Industry. “Providing superior hydrophobic properties and serving as carriers of the active components in industrial wood protection, products from our NYTEX portfolio can be specifically designed to meet the demands of any market.”
The naphthenic character of the oil facilitates both absorption during the wood impregnation process, and provides a water repellent effect, protecting the wood from degradation. The option to use bituminous molecules can further enhance the water repellent function and provide the dark pigmentation that is sometimes desirable in industrial wood treatment.
“The NYTEX grades used for wood-treatment are cost-effective and classified as non-hazardous to health and the environment. They also offer easy handling, allowing for transportation at ambient temperatures,” says Ana Cura.
The new, heavy duty wood impregnation using naphthenic oil has been proven to protect the wood from deterioration as long as or even longer than creosote-impregnated wood.
“This enables the railway, fencing and electrical utility industries to continue using the amazing, renewable material that is wood in a safe way,” concludes Ana Cura.