Waste/used crankcase oils priority substance list follow-up report: chapter 3

3. Exposure characterization

3.1 Environmental fate

The fate of used crankcase oils (UCOs) in the environment depends on how they are managed and re-used. For example, when UCOs are re-refined, the potential environmental exposure pathways are via air, receiving waters and solid waste from the re-refining facility. Similarly for fuel, exposure is via air and ash. For dust suppression and land disposal, key exposure routes are via land and runoff to water. When used for dust suppression, only 1% of the estimated amount of used mineral-based crankcase oil applied to two rural roads in New Jersey remained on the top 2.5 cm of the road surface material (Freestone, 1979). The majority of oil runoff from road surfaces was during the first few rainfalls following the oil application. During dry periods, the primary forms of transport were volatilization and dust transport. Dust particles may be carried by wind and may contaminate crops located near the oiled roads (Agency for Toxic Substances and Disease Registry (ATSDR), 1997). In general, biodegradation on road surfaces is minimal compared with losses from volatilization and runoff (ATSDR, 1997). In rural areas, the most common way to dispose of oil was pouring onto gravel roads and driveways (ATSDR, 1997).

The types of polycyclic aromatic hydrocarbons (PAH) present in UCOs can provide a fingerprint to distinguish the source of combustion (i.e., on-road vehicles vs. other combustion sources, such as home heating oil, coal and wood) (O'Malley et al., 1996; Barrie et al., 1997). Advances in analytical chemistry allow the identification of specific PAHs to provide a better understanding of the sources of petroleum hydrocarbons in urban runoff, specifically whether PAHs in environmental samples are attributable to UCOs. Latimer et al. (1990) analysed samples of petroleum products and probable source materials (e.g., roadside soil, street dust, roadside vegetation, atmospheric deposition) for hydrocarbons and trace metals and compared them with urban runoff samples from four different land use sites - commercial, residential, interstate highway and industrial - in various cities in Rhode Island in the United States. The chromatographic distributions of saturated and aromatic hydrocarbons revealed that PAHs in urban runoff at all four land use sites primarily originated from UCOs. The PAHs in the UCOs were two- to six-ring aromatics composed of approximately 36% fluoranthene and 38% pyrene, with smaller amounts (about 12-14%) of the benzopyrenes.

PAHs in stormwater runoff, where about 95% of the total aromatics were associated with the particulate phase, may be attributed primarily to UCOs (MacKenzie and Hunter, 1979; Carr et al., 2000). In a study performed by O'Malley et al. (1996), the primary sources of PAHs to marine surface sediments of St. John's Harbour, Newfoundland, were quantitatively assessed using a combination of molecular abundance and carbon isotope measurements of individual (four- and five-ring) PAHs. Mass balance calculation using a two-component mixing model showed that approximately 20-50% of four- and five-ring PAHs detected in the sediments originated from UCOs that originated from the crankcases of vehicles and entered the harbour in surface runoff (O'Malley et al.1996).

3.2 Environmental concentrations

Various components of UCOs are listed on Schedule 1 under the Canadian Environmental Protection Act, 1999 (CEPA) and were found in the following concentrations (µg/g wet weight): arsenic (<6.67); benzene (28); cadmium (0.479-0.93); chromium (1-21); PAHs, including pyrene (<0.128-326), phenanthrene (<0.224) and fluoranthene (<0.19-109); nickel (≤2); and lead (8.5)^{Footnote 3}. Schedule 1 substances that may be found in UCOs as contaminants include trichloroethylene (84); tetrachloroethylene (453); 1,1,1-trichloroethane (445); and polychlorinated biphenyls (PCBs) (0-38 000) (Canadian Council of Ministers of the Environment (CCME), 1989b; Environment Canada, 1993).

3.2.1 Dust suppressant and land disposal

No new monitoring data were found for the dust suppressant or disposal on land scenarios. However, data from Maltby et al. (1995a), O'Malley et al. (1996), Marsalek et al. (1997), and Abrajano (2000) on concentrations of UCOs in roadway runoff from vehicles leaking UCOs can be used as a surrogate for dust suppressant and land disposal concentrations released to the environment. This is possible since the route of entry from vehicular leakage of UCOs is the same as that for dust suppressant application and dumping on land, except the quantities involved for the two latter scenarios are expected to be considerably greater than that from roadway runoff.

Abrajano (2000) reported sediment concentrations for pyrene, fluoranthene and phenanthrene in ongoing work on source inputs of PAHs to the St. Lawrence River. By combining the molecular approach of identifying source inputs of PAHs with the compound-specific carbon isotope (¹³C/¹²C) signatures, it is possible to obtain a more quantitative assessment of the sources for PAHs in natural sedimentary environments (O'Malley, 1994; O'Malley et al., 1994). Table 1 lists sampling sites in the St. Lawrence River where petroleum-source PAHs were obtained. Using the carbon isotope apportionment model, the percentage of PAHs in these samples attributed as originating from UCOs is listed. Multiplication of total petroleum PAHs by the fraction of PAHs originating from UCOs provides the corresponding absolute contribution of UCOs to the sediment inventory of PAHs. The fraction of PAHs originating from UCOs was derived by mass balancing the carbon isotopes. For example, the total petroleum polycyclic aromatic hydrocarbon (PAH) concentration for pyrene in a sample taken near Cornwall is 1.558 µg/g dry weight and the percent UCOs-derived PAHs is 56; therefore, the concentration of PAHs that originated from UCOs at this site is 1.558 × 0.56 = 0.872 µg/g dry weight. The likely source of UCOs in sediment is runoff from roadways. Leaching of PAHs from asphalt was not considered a significant contributing factor. While contribution from land disposal, dust suppression and sewer release is possible, an actual amount is not known (Abrajano, 2000).

Table 1: Concentrations of three petroleum-derived PAHs found in sediment in the St. Lawrence River and percentage attributable to UCOs

In a study on highway runoff from the James N. Allen Skyway Bridge in Burlington, Ontario, Marsalek et al. (1997) reported maximum sediment event mean concentrations for pyrene, fluoranthene and phenanthrene of 3.00, 4.03 and 3.88 µg/g dry weight, respectively. The sediment event mean concentration is a constituent of the concentration and is calculated as the concentration mass in the storm runoff event divided by the event runoff volume. In this study, composite flow proportional samples were collected whereupon analysis of these samples yields the sediment event mean concentration directly. These sediment event mean concentrations represent averages of "instantaneous" concentrations (Marsalek, 2000).

In a British study by Maltby et al. (1995a), concentrations of PAHs in sediments collected at the Pigeon Bridge Brook location downstream from a major motorway were 10.16 µg/g wet weight for pyrene, 3.2 µg/g wet weight for fluoranthene and 5.62 µg/g wet weight for phenanthrene. Downstream sediments at this same location also contained significantly elevated median concentrations (µg/g dry weight) of metals compared with samples taken upstream of the motorways, as follows: zinc -- 137 (upstream), 338 (downstream); cadmium -- 0.93 (upstream), 2.28 (downstream); lead -- 86 (upstream), 133 (downstream); and chromium - 21 (upstream), 76 (downstream). Carbonyl compounds were also present in contaminated sediments but were absent from uncontaminated sediments.

Latimer et al. (1990) reported that the mean concentrations (µg/g dry weight) of total weighted hydrocarbons (includes PAHs) in particulates from urban runoff from four types of land use sites in Rhode Island were as follows: industrial, 211 000; commercial, 248 000; interstate highway, 248 000; and residential, 42 000. Latimer et al. (1990) also measured hydrocarbon and metal concentrations originating from UCOs in four source materials: street dust, roadside soil, vegetation and atmospheric deposition. Taken together, the street dust, roadside soil, vegetation and atmospheric deposition accounted for 20% of the particulate in urban runoff. Yet the urban runoff from the various land uses had higher concentrations of UCOs and PAHs than did the source materials. Direct dumping of oil down storm drains by do-it-yourself oil changers was expected to account for the difference in hydrocarbon concentration (including PAHs) between urban runoff and source materials (Latimer et al., 1990). The same explanation for the difference in hydrocarbon concentrations was also suggested in a survey in the same geographic location by Hoffman et al. (1980). The PAH distributions in the source materials were similar for all four land uses. Phenanthrene, fluoranthene and pyrene were the dominant compounds, with approximately 20% of the total being the benzopyrenes (Latimer et al., 1990).

Metal concentrations in urban runoff were also measured, and their concentrations and chemical distributions in the runoff and the source materials were similar. In roadside source materials, concentration ranges, in dry weight, were 0.02-3.40 µg/g particulate matter for cadmium, 10.4-228 µg/g for copper, 123-1410 µg/g for lead and 47.8-655 µg/g for zinc (Latimer et al., 1990).

3.2.2 Re-refining

No new monitoring data were found for this scenario.

3.2.3 Fuel

No new monitoring data were found for this scenario.