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7/140 Leak Impact Factor
I. Aquatic toxicity. Originally developed under the Clean sis allows certain substances to have their RQ ratings lowered
Water Act, the scale for aquatic toxicity is based on LC,,, one category (e.g., from RQlO to RQ 100). To be considered for
the concentration of chemical that is lethal to one-half ofthe the adjustment, the substance has to pass initial criteria dealing
test population of aquatic animals on continuous exposure with the tendency to bioaccumulate, environmental persist-
for 96 hours (see Table 7.1; also see the Notes on toxicity ence, presence of unusual hazards (such as high reactivity), and
section later in this chapter). the existence of hazardous degradation or transformation prod-
2. Mammalian toxic@. This is a five-level scale for oral, der- ucts. If the substance is not excluded because of these items, it
mal, and inhalation toxicity for mammals. It is based on may be adjusted downward one RQ category if it shows a very
LC,, data as well as LD,, (the dose required to cause the low persistence.
death of 50% of the test population) data and is shown in Unfortunately, petroleum, petroleum feedstocks, natural
Table 7.2. gas, crude oil, and refined petroleum products are specifically
3. Ignitability and reactivity. Ignitability is based on flash excluded from the EPA’s reportable quantity requirements
point and boiling point in the same fashion as the acute char- under CERCLA. Because these products comprise a high per-
acteristic, N, Reactivity is based on a substance’s reactivity centage of substances transported by pipeline, an alternative
with water and with itself. For ourpurposes, it also includes scoring system must be used. This requires a deviation from the
pressure effects in the assessment of acute hazards. direct application of the EPA rating system when petroleum
4. Chronic toxicity. To evaluate the toxicity, a scoring method- products are evaluated. For our purposes here, however, we can
ology assigns values based on the minimum effective extend the spirit of the EPA system to encompass all common
dose for repeated exposures and the severity of the effects pipeline products. This is done by assigning RQ equivalent
caused by exposure. This scoring is a fimction of pro- classifications to substances that are not assigned an RQ classi-
longed exposure, as opposed to the acute factor, N,, which fication by the EPA.
deals with short-term exposure only. The score determina- For the products not specifically listed as hazardous by EPA
tion methodology is found in U.S. regulations (48 CFR regulatory agencies, a general definition is offered. If any one
23564). of the following four properties are present, the substance is
5. Potential canzinogenicity This scoring is based on a high considered to be hazardous [14]:
weight ofevidence designation (either a “known,” “probable,”
or “possible” human carcinogen) coupled with a potency rat- 1. Ignitubility. Defined as a liquid with a flash point of less
ing. The potency rating reflects the relative strength of a sub- than 60°C or a nonliquid that can spontaneously cause a fire
stance to elicit a carcinogenic response. The net result is a through friction, absorption of moisture, or spontaneous
high, medium, or low hazard ranking that corresponds to RQs chemical changes and will burn vigorously and persistently.
of 1,10, and 100 pounds, respectively [30]. 2. Corrosivity. Defined as liquids with pH I2 or t 12.5, or
with the ability to corrode steel at a rate of 6.35 millimeters
per year at 55°C.
Secondary criteria 3. Reuctivity. Defined as a substance that is normally unstable,
reacts violently with water, forms potentially violent mix-
As previously stated, the final RQ rating may be adjusted by tures with water, generates toxic fumes when mixed with
evaluating the persistence of the substance in the environment. water, is capable of detonation or explosion, or is classified
The susceptibility to biodegradation, hydrolysis, and photoly- as an explosive under DOT regulations.
4. Extraction procedure toxicity. This is defined by a special
test procedure that looks for concentrations of materials
Table 7.1 Aquatic toxicity listed as contaminants in the Safe Drinking Water Act’s list
of National Interim Primary Drinking Water Regulation
RQ (lb) Aquatic toxic@ (LC,, range) (mg/L) contaminants [14].
1 <o. 1 Although petroleum products are specifically excluded from
10 0.1-1 .o
100 1-10 regulatory control, these definitions would obviously include
1000 10-100 most pipeline hydrocarbon products. This then becomes the
5000 10&500 second criterion to be made in the evaluation of pipeline
products,
~ ~~~ ~
Table 7.2 Mammalian toxicity
Mammalian toxicity
~~
RQ (lbl Oral LD,, range (mg/kg) Dermal LD,, range (mg/kg) Inhalation LC,, mnge @pm)
1 <o. I <0.04 m&g <0.4 ppm
10 0.1-1 0.04-0.4 0.44
100 1-10 0.44 4-40
1000 I &IO0 4-30 40400
5000 100-500 40-200 400-2000