API PUBL 4733:2004 pdf download

API PUBL 4733:2004 pdf download.Risk-Based Screening Levels for the Protection of Livestock Exposed to Petroleum Hydrocarbons.
3.2.3 Direct Ingestion
Cattle may directly ingest crude oil and other petroleum compounds from pools of oil formed by leaking pipelines or storage tanks tEdwards and Zinn 1979: Coppock et aL 1995: CCME 20601 due to curiosity (particularly in young calves: F.dwards l985b), or to add salt to their diet (F4wanLs l9g5b. Coppock ci al. 1995). Reported cases include sicers consuming petroleum distillate, drinking from a slush pit. and drinking petroleum from puddles near a tank battcry (Edwards and Zinn 1979). Oil and natural gas industry guidance (API 1997) and many regulatory agencies (e.g., the Railroad Commission of Texas 1993) stress the importance of removing free-oil accumulations on the ground that animals could potentially ingest.
3.2.4 Dermal Absorption
Dermal absorption of petroleum hydrocarbons in livestock is considered a minor exposure pathway because of their thick coats (CCME 2000). While methods are available to assess dermal exposure to humans, data necessary to estimate dernial exposure are generally not available for livestock or wildlife tEPA 1993). Additionally. dermal exposure has been shown to be negligible for most terrestrial nianinials (EPA 2000).
3.2.5 Inhalation
According to CCMF. (2000). inhalation of petroleum hydrocarbons is also a minor exposure pathway for livestock. Inhalation of petroleum hydrocarbons was assumed to be negligible for two reasons: (I ) due to the assumed presence of vegetation on grazing lands, exposure of contaminated surface soils to winds and resulting aerial suspension of contaminated dust particulatcs would be minimized, and (2) most volatile organic compounds (VOCs)—the contaminants most likely to present a risk through inhalation—get rapidly diluted and dispcrscd in ambient air, making significant exposure to VOCs through inhalation unlikely. In situations where inhalation exposure is believed to be more significant, evaluation of this pathway should be considered.
3.2.6 Plant Ingestion
Exposure to petroleum hydrocarbons through ingestion of plants is considered a minor pathway (CCME 200(b. The authors explain that although the ingestion rates of plants are high for livestock, plants ate considered a minor contributor to this proportion, due to the limited phytoaccumulation (i.e.. a process by which plants accumulate contaminants into roots and above ground shoots or leaves) potential of petroleum hydrocarbons (CCME 2000; Alberta Environment 2001a).
3.3 Summary of the CSM for Livestock
If the CSM can identify any complete and significant exposure pathway(s) for livestock receptors at a site, then the next step would he to conduct a screening-level risk assessment. However, another factor to consider in determining whether there is need to assess livestock risks is the size of the contaminated area or release relative to the size of the grazing area. This is referred to as a site use factor explaincd further in the following section). A small affected area (e.g. less than one acre) is unlikely to result in significant risks to herds of livestock arid may not warrant a screening-level risk assessment (l’e,as Natural Resource Conservation Commission (TNRCCI 2(XX) and Pennsylvania Department of Environmental Protection IPADEPI l99). Cumulative risks can be estimated for livestock receptors exposed to petroleum hydrocarbons via multiple exposure pathways (for example. via soil ingestion and water ingestion at a site).
A screening-level risk assessment uses a conservative approach to determine any potential risk to receptors exposed to contaminants at a site which includes comparing exposure levels of contaminants from a site to appropriate threshold values (ie., toxicity values and guidelines). To characterize potential risks to livestock, petroleum hydrocarbon exposure levels from a site can be compared to petroleum hydrocarbon threshold levels protective of livestock.
As explained earlier, the approach described in this report is general, not site- specific. Therefore, threshold values were developed for the primary exposure pathways: 1) drinking water ingestion, and 2) incidental soil ingestion. Although, direct ingestion was also considered a significant exposure pathway (Figure 1), site-specific parameters are required to develop threshold values for this pathway and therefore, were not addressed in this report.