Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 25
25
Table 7. Chemical structures for propanal (propionaldehyde), butanal,
butene, crotonaldehyde, and their corresponding surrogate compounds.
HAP without Toxicity Criteria Surrogate Compound
O
O
O H
Propanal Butanal Acetaldehyde
(Propionaldehyde)
Butene Propene
O
Crotonaldehyde Acrolein
CR ATcancer increasing severity, for exposure periods ranging from 10 min
RBCcancer (g/m3 ) = × to 8 hr. For this analysis we selected AEGL-1 values, which
IUR EF × ED
ATnoncancer correspond with concentrations at which the general popula-
RBCnoncancer (g/m3 ) = 100 × HQ × RfC × tion, including susceptible subpopulations, might experience
EF × ED
transient and reversible discomfort or irritation, but not any
Where: disabling effects (NRC 2007). Acute MRLs are developed by
ATcancer = Averaging time - cancer (25550 days); ATSDR, and represent a concentration that would not be
ATnoncancer = Averaging time - noncancer (10950 days); associated with adverse health effects including in sensitive
CR = Acceptable cancer risk (1 × 10-6); individuals (i.e., a "no-effect" concentration), for an expo-
ED = Exposure duration (30 years); sure period of 114 days. Acute RELs are developed by
EF = Exposure frequency (350 days/year); California Environmental Protection Agency's Office of
HQ = Hazard quotient (1); Environmental Health Hazard Assessment. As with the acute
IUR = Inhalation unit risk (risk per g/m3 - chemical MRLs, the acute RELs represent a "no-effect" concentration
specific); and at which no adverse health effects are expected, including for
RfC = Reference concentration (mg/m3 - chemical the most sensitive individuals in an exposed population
specific). (CalEPA 1999). Acute RELs are applicable to a 1-hr exposure
period unless they are based on reproductive or develop-
We used standard assumptions for averaging time, expo- mental endpoint, in which case they are applicable to an
sure duration, and exposure frequency, as recommended by exposure period of several hours. Toxicity criteria for evalu-
EPA (USEPA 1989). ating acute exposures are presented in Table 8.
Table 3 listed RBCs along with relative emissions factors As noted in Section 2, toluene and xylene are emitted in
for airport-related HAPs. fairly large quantities, yet what is currently known regarding
their toxicity indicates they are much less of a health concern
than that of the prioritized HAPs identified in this analysis.
4.4 Evaluation of Acute Exposures
As indicated by the values in Table 8, this is true for both
for Aviation-Related HAPs
chronic and acute toxicity. The determination that toluene
For evaluating acute effects the report researchers identi- and xylene airport emissions likely do not present a substan-
fied acute exposure guidelines (AEGLs), acute minimal risk tial health concern is supported by an evaluation of acute
levels (MRLs), and acute inhalation reference exposure levels human health risks for Oakland International Airport (CDM
(RELs). AEGLs are developed through a federal advisory 2003). This evaluation indicates that CalEPA's acute RELs for
committee with input from stakeholders for use in chemical toluene and xylene are more than 2,000-fold greater than
emergency planning, prevention and response programs, and estimated air concentrations, which provides a very wide
include peer review by the National Research Council margin of safety to account for any uncertainties in estimates
(USEPA 2007). AEGLs are established at three levels, with of toxicity or exposure.
OCR for page 26
26
Table 8. Acute toxicity criteria for airport-related hazardous
air pollutants.
Toxicity Criterion (ppm)
RELa AEGL-1 AEGL-1 MRL
HAP 16 Hours 1 Hour 8 Hour 114 Days
Acetaldehyde 45 45
Acetone 200 200 26
Acrolein 0.00008 0.03 0.03 0.003
Benzene 0.4 52 9 0.009
1,3-butadiene 45 45
Formaldehyde 0.08 0.9 0.9 0.04
Methanol 530 270
Phenol 1.5 15 6.3 0.02
Propane 5,500 5,500
Styrene 5 20 20
Toluene 10 200 200 1
Xylenes 5 130 130 2
Data Sources: ATSDR 2007a (MRLs); CalEPA 1999 (RELs); USEPA 2007 (AEGLs ).
Notes:
ppm parts per million
HAP hazardous air pollutant
REL reference exposure level
AEGL acute exposure guideline
MRL minimum risk level
a
Benzene REL is for a 6-hr exposure period, all other RELs are for a 1-hr exposure period.
