ASTM E981-04(2012)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E981 − 04 (Reapproved 2012)
Standard Test Method for
Estimating Sensory Irritancy of Airborne Chemicals
This standard is issued under the fixed designation E981; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope the concentration-response curve constructed from the various
data points obtained with a series of concentrations.
1.1 This laboratory test method provides a rapid means of
determining sensory irritant potential of airborne chemicals or
3. Significance and Use
mixtures.Itmayalsobeusedtoestimatethresholdlimitvalues
(TLV) for man. However, it cannot be used to evaluate the 3.1 This test method was developed to meet the following
relative obnoxiousness of odors.
criteria:
3.1.1 It provides positive recognition of sensory irritants of
1.2 This test method is intended as a supplement to, not a
widely varying potencies.
replacement for, chronic inhalation studies used to establish
3.1.2 It is sufficiently simple to permit the testing of large
allowable human tolerance levels.
numbers of materials.
1.3 This standard does not purport to address all of the
3.1.3 This test method is capable of generating
safety concerns, if any, associated with its use. It is the
concentration-responsecurvesforpurposesofcompoundcom-
responsibility of the user of this standard to establish appro-
parison.
priate safety and health practices and determine the applica-
3.1.4 This test method has good reproducibility.
bility of regulatory limitations prior to use. Specific hazard
3.2 This test method can be used for a variety of divergent
information is given in Section 6.
purposes, including the assessment of comparative irritancy of
compoundsorformulationsandsettinginterimexposurelevels
2. Summary of Test Method
for the workplace (1, 2).
2.1 This test method quantitatively measures irritancy as
3.3 It has been shown that for a wide variety of chemicals
indicatedbythereflexinhibitionofrespirationinmiceexposed
and mixtures, a perfect rank order correlation exists between
to sensory irritants.
the decreases in respiratory rate in mice and subjective reports
2.2 Four mice are simultaneously exposed to the airborne
of sensory irritation in man (1, 3, 4, 5).
chemical. Usually a sufficient number of groups of animals are
3.4 Aquantitativeestimateofthesensoryirritancyofawide
exposed to a geometric series of concentrations so that a
variety of materials can be obtained from concentration-
concentration-response curve can be constructed. For simple
response curves developed using this method (1, 3, 4, 6, 7, 8,
preliminary comparisons, however, a single group of four
9).
animals at one concentration will suffice.
3.5 Although this test method is intended to measure sen-
2.3 The mice are placed in a body plethysmograph attached
sory irritation of the nasal mucosa, the cornea is innervated by
to an exposure chamber so that only the head is exposed to the
the same nerve. This animal model will, therefore, allow an
test material. The plethysmographs are connected to pressure
estimate of the irritant potential of cosmetic ingredients or
transducers, which sense changes created by inspiration and
other household products to the eye, assuming that they can be
expiration.Theamplifiedsignalsaretransmittedtoapolygraph
aerosolized (10).
recorder.
3.6 This test method is recommended for setting interim
2.4 The concentration of airborne irritant that produces a
guidelines for exposure of humans to chemicals in the
50% decrease in respiratory rate (RD50) is determined from
workplace, to assess acute sensory irritation resulting from
inadvertent spills of household products, and to assess the
comparativeirritancyofformulationsormaterialsintendedfor
This test method is under the jurisdiction of ASTM Committee E50 on
a variety of uses (see Appendix X2).
Environmental Assessment, Risk Management and Corrective Action and is the
direct responsibility of Subcommittee E50.47 on Biological Effects and Environ-
mental Fate.
Current edition approved Dec. 1, 2012. Published December 2012. Originally
approved 1984. Last previous edition approved in 2004 as E981–04. DOI: Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
10.1520/E0981-04R12. this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E981 − 04 (2012)
NOTE 1—Taken from Ref. (3).
FIG. 1 Typical Tracing of Normal Mouse Respiration (Top), and of a“ Moderate” Sensory Irritant Response (Bottom)
4.3 Exposure Chamber, constructed entirely of glass, with a
volume of 2.3 L.
4.4 S.T.103/60GroundGlassJoint,thatallowsaccesstothe
inside of the exposure chamber.
4.5 Perforated Rubber Dental Dam, reinforced with electri-
cal tape.
4.6 Rubber Stoppers.
4.7 “T”Tube,withatube6cmlongandthe“T”12cmlong.
4.8 Vacuum Pump.
4.9 Flowmeter.
4.10 Absolute Filter.
4.11 Sodium Carbonate-Activated Charcoal Filter.
4.12 Pressure Transducer.
4.13 Polygraph Recorders.
NOTE 1—Taken from Ref. (8).
4.14 Frequency-to-Voltage Converter, operating in the aver-
FIG. 2 Typical Tracing of Normal Mouse Respiration (Top), a Mod-
aging mode instead of the pulse mode. See Appendix X1.7.
erate Pulmonary Irritant Response (Center), and an Extreme Pul-
4.15 VoltageAdditionandDivisionEquipment,toobtainthe
monary Irritant Response (Bottom)
signal average for four mice.
4.16 Signal Averages.
3.7 This test method will detect irritating effects at concen-
4.17 Oscillograph.
trations far below those at which pathological changes are
observed (9).
4.18 Aerosol Generator.
NOTE 1—A good overview of the toxicological evaluation of irritant
4.19 Timer.
compounds is given in Ref (8).
4.20 Control Valve.
4. Apparatus
5. Reagents
4.1 The apparatus required to perform this test is listed
5.1 Technical reagents may be used in all tests where
below. The basic components for testing any type of material
arethesame.Alistofsuitableapparatusandsuppliersisfound solvents other than water are required.
in Appendix X1.
5.2 Solutions containing 1 to 3% of the test material are
4.2 Plethysmograph Tubes. used for comparative studies.
E981 − 04 (2012)
6. Hazards
6.1 Not all compounds that cause a decrease in respiratory
rate are sensory irritants. To be characterized as a sensory
irritant,acompoundmustproduceanetdecreaseinrespiratory
rate as a result of the characteristic pause during expiration as
showninFig.1.Thispausedifferentiatessensoryirritantsfrom
pulmonary irritants, general anesthetics, and asphyxiants,
which also reduce respiratory rate, but as a result of a pause
between breaths as shown in Fig. 2.
6.2 It is possible for one component to alter the effect of
another in a mixture, depending on their respective concentra-
tions (12). Additive and antagonistic responses are possible.
For this reason the effects of each compound in a formulation
should be assessed before any test is made for interactions.
6.3 Although the test procedure has been found to show a
high correlation for sensory irritants with established TLV
values for man, it may well predict values that are too high for
compounds of low reactivity that are metabolically activated,
and also for pulmonary irritants (10).
7. Test Animals
7.1 Mice are the subjects to be used for this test. It is
imperative that they meet the specifications outlined here.
Although any mouse of the proper size could be used, marked
differences have been observed between different strains and
sexes (2).
7.1.1 Male Swiss-Webster mice shall be used as the test
subjects.
7.1.2 Only animals weighing between 22 and 28 g may be
used. Smaller mice might be able to crawl into the exposure NOTE 1—Taken from Ref. (11).
FIG. 4 Diagram of Test Apparatus
chamber,whilelargeronesmaynotbeabletobreathenormally
in the apparatus.
NOTE 1—Dimensions are in centimetres.
NOTE 2—Taken from Ref. (11).
FIG. 3 Glass Exposure Chamber with Attached Body Plethysmographs
E981 − 04 (2012)
7.1.3 The same system can be used with guinea pigs or rats
with an airflow of 2 L/min when using head dome (9).
8. Preparation of Apparatus
8.1 Exposure Chamber:
8.1.1 The heads of each of four mice extend into the
exposure chamber, and the bodies are contained in plethysmo-
graph tubes. Perforated rubber dental dam reinforced with
electrical tape provides tight but comfortable seals around the
animals’ necks, and rubber stoppers prevent them from back-
ing out of the tubes, and provides an airtight body plethysmo-
graph (see Fig. 3).
8.1.1.1 The “T” tube is of the same diameter as the inlet to
the chamber. The gas or aerosol from the generator enters one
sideofthe“T”andthemakeupairentersontheother.Thusthe
tube acts as a miniature mixing chamber, eliminating the need
for a baffle plate. The “T” tube is not shown in Fig. 3.
8.1.2 Chamber Equilibration:
8.1.2.1 It is desirable to reach equilibrium of the test
materialintheexposurechamberinasshortatimeaspossible.
In no case should this time exceed one-tenth of the total
exposuretime.Thevalidityofthedataforextrapolationtoman
requires rapid attainment of maximum concentration.
8.1.2.2 Equilibration time in minutes is 5.0 times the cham-
ber volume in litres divided by airflow through the chamber in
litres per minute (13).
8.2 A vacuum pump with a control valve monitored by a
flowmeter provides a constant airflow through the exposure
chamber. Chamber effluent is passed through an absolute filter
and then a sodium carbonate-activated charcoal filter before
exhausting, preferably into a fume hood. (See Fig. 4.)
8.3 Eachofthefourplethysmographtubesisconnectedtoa NOTE 1—Taken from Ref. (13).
FIG. 5 Schematic Representation of the Pitt No. 1 Aerosol Gen-
pressure transducer. As the mouse inhales, a positive pressure
erator
is created and exhalation results in a negative pressure. The
amplified signals are recorded on a polygraph, which has the
polarity set so that an upward deflection is obtained during made from the total airflow used in the chamber. At the
standard flow rate of 20 L/min through the chamber, delivery
inspiration and a downward deflection is obtained during
expiration. The signal from each transducer is also fed into a tothegeneratorof0.22mLofacetoneperminutewillresultin
a concentration of 2800 to 3000 ppm. With acetone there will
frequency-to-voltage converter, and then fed into a signal
averager. The output of the averager is displayed on a second be no liquid overflow, but with aqueous solutions, 1.0 mL/min
is high enough so that liquid will fall to the bottom of the
recorder, thus permitting continuous monitoring of the average
generator.Thisiscollectedinareservoirviatheoverflowtube.
respiratory rate of the four mice. (See Fig. 4.)
8.4.2 Arrows in Fig. 5 indicate the path that the aerosol will
8.4 Asuitable generator for this test is a glass Dautrebande-
follow. Polyethylene Glycol 200 (PEG 200) can be used as a
type generator modified to allow continuous feed of test
3 solventinsteadofwater.Theairpressureshouldbeabout20to
material. Thisgeneratorcanbeusedforvolatileornonvolatile
25 psig with this solvent. Dry air must be used with PEG 200,
liquids, solutions, or suspensions of solids. It is depicted
whichishygroscopic.Usingthisgeneratorwitha1%solution
schematically in Fig. 5.
of test material in water and 20 L/min flow rate through the
8.4.1 For aqueous solutions, liquid is delivered via a pump
exposure chamber, the concentration in the chamber will be
regulated at 1.0 mL/min to the right-hand tube. This delivery
between 10 to 20 mg/m and most particles will be submi-
rate can be varied by a factor of 3 to 4. Air is delivered at 10
cronic.
to12psigwhenawatersolutionisused,and8to10psigwhen
8.4.3 The Dautrebande-type generator can also be used to
acetone solution is used. With acetone the amount of solution
vaporize liquids for exposure of animals to vapors. For this
delivered is restricted so that no more than 3000 ppm acetone
purpose, the liquid is delivered at a known rate by a regulated
vapor is produced in the exposure chamber. The calculation is
pump and airflow is set at 10 to 20 psig. For liquids of lower
vapor pressure, heating tape can be used around the generator
to increase vaporization efficiency. For aerosols or vapors
PittNo.1aerosolgeneratoravailablefromScientificGlassblowingLaboratory,
McKees Rocks, PA 15136, has been found suitable. likely to oxidize rapidly in air, dry nitrogen should be used
E981 − 04 (2012)
NOTE 1—Taken from Ref. (11).
FIG. 6 Typical Tracing Obtained from a Single Animal Prior to and During Exposure to a Sensory Irritant (Top). Average
Respiratory Rate of Four Mice During Course of Exposure (Bottom)
instead of air. When this is done, pure oxygen is added to the used to replace the frequency-to-voltage converter and signal-
chamber airflow to maintain 18 to 20% O in the exposure averaging device. The magnetic tape is not required, and a
chamber. When suspensions are to be tested, the suspended four-trace oscilloscope with storage capability can replace
material must be very fine to prevent clogging of the tip on the oscillograph No. 1.
generator. Although larger tips can be used if required, a
degradation of aerosolizing performance will result from their
9. Sample Preparation
use.
9.1 Because of the large variety of chemicals and formula-
8.5 Tostartandstoptestmaterialgeneration,atimerandan
tions that can be tested by this procedure, and the tremendous
associated control valve are needed in conjunction with the
differences in irritant potential between them, no specific
aerosol generator.
stipulation for sample preparation can be made. The only
requirement for concentration is that the levels to be tested are
8.6 When using water or acetone a “dry” particle will be
spaced at even logarithmic intervals to allow good
produced, since both solvents will evaporate. However, PEG
concentration-response curves to be generated from the data
200 will not evaporate and a liquid droplet is obtained. Mass
obtained. The information provided in the succeeding para-
concentration in the chamber should be obtained by sampling
graphsofthissectionisthereforeintendedforgeneralguidance
on filters and weighing on an appropriate balance. A better
only.
method, but one not required in a screening experiment, is
appropriate chemical analysis. When acetone is used, its
9.2 For solids and nonvolatile liquids, solutions are pre-
concentrationinthechambershouldbeverified.Indicator
...