Creosote-Impregnated Waste Materials

Creosote is used in Canada as a heavy-duty wood preservative for railway ties, bridge timbers, pilings, and large-sized lumber. It is composed of hundreds of compounds, the largest group being the polycyclic aromatic hydrocarbons (PAHs). In this assessment, the substance "creosote-impregnated waste materials" (CIWM) includes creosote waste products and creosote-contaminated sites. Creosote waste products are wood materials treated with creosote that have since been removed from service and are awaiting disposal (used railway ties, utility poles, etc.), and creosote-contaminated sites are areas of contaminated soil, water, or materials resulting from the application, manufacture, storage, transportation, or spillage of creosote.

Railway ties constitute the largest volume of creosote waste products generated in Canada. The major railways decommission 4.5 million ties per year (450 000 m3 of wood) containing an estimated 20.2 x 106 kilograms of creosote. It is estimated that 90% of all railway ties removed each year are reused. This leaves roughly 2.02 x 106 kg/yr of creosote in discarded railway ties. Other creosote waste products are generated when docks, breakwaters, railway trestles, and bridges are decommissioned. Studies were not identified that could be used to determine whether creosote waste products could cause harmful effects on the environment.

Estimates of the amounts of waste creosote entering the Canadian environment from creosote-contaminated sites are not available for many sites. However, for most of the sites where hydrogeological surveys have been done, large amounts of waste creosote have been discovered in soil, groundwater, and some surface waters. There is an stimated 256 000 m 3 of moderately and highly contaminated soil from 11 abandoned or operating creosote-treating facilities in Canada. Waste creosote is known to be entering the soils, groundwaters, and surface waters at 24 creosote-contaminated sites spread across all of the provinces, except Prince Edward Island. Groundwater has been severely contaminated at several creosote-contaminated sites. Benthic organisms and the general health of the aquatic ecosystem near a major wood-treatment facility in Thunder Bay, Ontario have been adversely affected by the presence of waste creosote pooling on the sediments.

Environmentally sensitive benthic invertebrates [Trichoptera (caddisflies) and Plecoptera (stoneflies)] were significantly reduced in numbers from a kilometre length (approximately) of the south half of the Bow River downstream from another major wood-treatment facility in Calgary. These species had been replaced by less sensitive Gastropods (snails) and Diptera (crane flies). Waste creosote and the PAHs found in it have been detected in Canadian freshwater sediments near creosote wood preservation plants at levels higher than those known to cause severe effects to freshwater and marine organisms. There are strong correlations between the presence of PAHs from CIWM sources in the sediments of Eagle Harbor, Washington and the Elizabeth River, Virginia, the levels of PAHs found in the tissues of fish in these two aquatic systems, and liver tumors discovered in these fish.

There is insufficient information to estimate exposure of humans to the components of waste creosote from creosote-impregnated waste materials. In addition, information was not identified on the effects of CIWM to the environment upon which human life depends. Therefore, detailed consideration of whether this substance is "toxic" as defined under Paragraphs 11 (b) and 11(c) of the Act is not included in this assessment.

Creosote Waste Products
Therefore, on the basis of available data, it is not possible to determine whether materials leaching from creosote waste products (i.e., used railway ties and utility poles) are entering or may be entering the environment in a quantity or concentration or under conditions that are having or may have a harmful effect on the environment.

Creosote-contaminated Sites
Therefore, on the basis of available data, materials from creosote-contaminated sites are entering or may be entering the environment in a quantity or concentration or under conditions that are having or may have a harmful effect on the environment.

View or download the full Priority Substances List Assessment Report on Creosote-Impregnated Waste Materials (PDF).