Utility and Railway Rights‐of‐Way Contaminants: Dioxins and Furans

Abstract

AbstractUtility and railway right‐of‐way (ROW) ditches flowing into salmon (Oncorhynchus spp.) streams in the Lower Mainland of British Columbia were sampled in 1990 and 1991 to determine the occurrence and concentrations of selected chlorinated dibenzo‐p‐dioxins (CD) and chlorinated dibenzofurans (CF). Parkland and farmland ditches were also sampled to establish the background concentrations of these chemicals. As well, treated wood utility pole and railway tie samples were collected to confirm the source of CD and CF. Treated wood utility poles contained about 76 700 µg/kg CD and 18 700 µg/kg CF. In railway ties, 13 500 µg/kg CD and 2290 µg/kg CF were found. Although CD and CF were not found in parkland waterways, they were detected in farmland, utility, and railway ROW ditches. Varying mean concentrations of CD (2.2–13 100 ng/L) and CF (0.40–3180 ng/L) were detected in ditch water. In ditch sediments of the same sites, the average CD and CF concentrations ranged from 3.7 to 2580 µg/kg and 0.7 to 1280 µg/kg, respectively. Representative tetra‐, penta‐, hexa‐, hepta‐, and octa‐CD and CF homologs were also detected in ditch water and sediments. Tetra‐CD and tetra‐CF levels found in ditch water adjacent to treated poles did not exceed the 96‐h LC50 (lethal concentration of a chemical to 50% of test organisms) of salmonids and aquatic invertebrate. The biological/toxicological implications to these organisms of high levels of dioxins and furans other than tetra‐CD/CF in sediments and water are discussed.