Document Ne6LGzZw2drgwaDpQQXM4YDVg
MEMORANDUM
t
To: Mr. J. A. Fisher
Ct: See Attached Distribution List
From:
J. N. Derrait
Date:
September 9, 1974
Subject: Table I Revision in the Report, "The Characterization
of the Odor Properties of 101 UCC Petrochemicals using Sensory Methods."
Attached is a revised Table I of the subject report (July 10, 1973, File No. 18541) written by Dr. T. M. Heilman.
By copy of this memorandum I am requesting that all recipients of the original report discard Table I and attach the revised Table. You will note in the revised Table that ten new compounds have been added, indicated by a single asterisk and there is one compound correction indicated by a double asterisk.
We will continue to expand the number of compounds in
this Table and issue revisions from time to time,
*
*
JND:gc Attachment
Revised Table I
t-'
f*
UCC 100034
UCC 100035
TABLE I SUMMARY OF ODOR DATA
Compound
Acetic Anhydride *- Acetone
Acetophenone Acrylic Acid Amyl Acetate, Primary
(Mixed Isomers) Amyl Alcohol Bicyclononadicne 1,3-Butadlene n-Butanol 2-Butanol -- Butyl Acetate n-Butylamine Butyl CELLOSOLVE Butyl CELLOSOLVE Acetate n-Butyl Chloride n-Butyl Ether Butylene Oxide Butyraldehyde CARBITOL Acetate CARBITOL Solvent CELLOSOLVE Acetate CELLOSOLVE Solvent Cumene -- Cyclohexanone Cyclopent adiene Diacetone Alcohol Di -N-Butylamlne Di cyclopentadiene * * Diethylamine Diethyl Ethanol amine Di isobutyl Carbinol -- Diisobutyl Ketone Di isopropylamine Dimethyl Ethanolamine 1-4,Dioxane 1-3, Dioxolane Di -N-Propyl ami ne
Absolute ppm
<0.14 20.0
0.30 0.094 0.067
0.12 0.014 0.45 0.30 0.12 0.006 0.08 0.10 0.11 8.82 0.07 0.07 <0.0046 0.026 <0.21 0.056 0.30 0.008 0.12 0.010 0.28 0.08 0.011 0.04 0.011 0.032 <0.11 0.13 0.015 0.80 16.9 0.02
New Compound Additions Corrected Data
50% Recognition
PPm
0.36 32.5
0.60 1.04 0.15
1.0 0 .085 1.1 1.0 0.41 0.037 0.24 0.35 0.20 13.3 0.24 0.71 0.0092 0.157 1.10 0.138 0.55 0.047 0.12 0.016 1.1 0.27 0.020 0.28 0.04 0.048 0.31 0.38 0.045 1.8 64.0 0.10
100%
Recognition ppm
Odor Index 100%
Recognition
0.36 140.0
0.60 1 .04 0.21
14,611 1,742
2,183 105,700
25,047
1.0
0.112 1.3 2.0
0.56 0.037 0.24 0.48 0.20 16.7
0.47 0.71 0.039
0.263 1 .10 0.250 1.33 0.047 0.24 0.016 1.7
0.48 0.020 0.49
0.04 0.160 0.31
0.85
0.045 5.7 128.0 0,10
**
13.150 -
769,230 2,630
28,179 284,300 449,166
2,729 6,550 6,377 13,978 260,563 2,984,615
498 600 10,520 3,909 83,000 10,958 " 776 5,479 440,500
33,000 8,187 4,258
92,823 116,888
6,228 804
270,600
(continued)
Quality
Sour Acid Sweet/Fruity Sweet/Almond Rancid/Sweet Sweet/Ebter/Banana
Sweet Sharp Undefined Rancid/Sweet Sweet Sweet/Bster Sour/Amrooniacal Sweet/Ester Sweet/Elster Pungent Fruity/Sweet Sweet/Alcohol Sweet/Rancid Sweet Sweet/Musty Sweet/Musty Sweet/Musty Sharp Sweet/Sharp
-
Sweet Fishy/Amine Sweet/Sharp Musty/Fishy/Amine Amine Sweet/Alcohol Sweet/Sster Fishy/Amine/Ammoniacal Amine Sweat/Alcohol Sweet/Musty Amaoni acal /Ami ne
Hedonic Tone
Neutral to Unpleasant Pleasant to Neutral Pleasant Unpleasant Pleasant
Pleasant Pleasant Unpleasant to Neutral Neutral to Unpleasant Pleasant to Neutral Pleasant Unpleasant to Pleasant Pleasant Pleasant Unpleasant Pleasant Pleasant Unpleasant Pleasant to Unpleasant Neutral PI eas a nt Unpleasant to Pleasant Unpleasant Pleasant Pleasant Unpleasant to Pleasant Unpleasant to Neutral Unpleasant Unpleasant Unpleasant PI eas ant Pleasant Unpleasant to Pleasant Unpleasant Pleasant Neutral Unpleasant to Neutral
TABLE I (continued)
Compound
Absolute ppm
Dripollne "C"
0.035
Ethanol
0.30
Ethyl Acetate
6.3
Ethyl Acrylate
0.0002
Ethylamine (70-72% In water ) 0.27
Ethylene
260.0
Ethylenediamine
1.0
Ethylene Dichloride
6.0
Ethylene Oxide
260.0
2-Ethylbutanol
0.07
2-Ethyl llexanol
0.075
Ethylhexyl Acetate
0.1
2-Ethylhexyl Acrylate
0.073
Ethylidene Norbornene
0.02
2-Et hoxy-3,4-Dihydro-1,
0.020
2-Pyran
N-Ethyl Morpholine
0.08
Glycol Diacetate
0.093
1-Hexanol
0.01
Isobut anol
0.68
Isobutyl Acetate
0.35
Isobutyl Acrylate
0.002
Isobutyl CELLOSOLVE
0.019
Isobutyraldehyde
0.047
Isodecanol
0.020
Isopentanoic Acid,
0.005
Mixed Isomers
Isophorone
0.20
Isopropanol (Anhydrous)
3.20
Isopropyl Acetate
0.49
Isopropylamine
0.21
Isopropyl Ether
0.017
Mesityl Oxide
0.017
Methanol
4.26
Methyl Amyl Acetate
<0.07
Methyl Amyl Alcohol
0.33
2-Methyl Butanol
0.04
Methyl CELLOSOLVE
<0.09
Methyl CELLOSOLVE Acetate Methyl Chloride
0.34 -
New Compound Additions
50% Recognition
ppm
0.176 1.0 13.2 0.00030 0.83 400.0 3.4 40.0 500.0 0.77 0.138 0.21 0.18 0.073 0.10
0.25 0.312 0.09 1.80 0.50 0.009 0.114 0.141 0.031 0.015
0.54 7.50 0.90 0.71 0.053 0.051 53.3
0.23 0.52 0.23 0.22 0.64 -
100% Recognition
_____ PPP...
0.421 1.0 13.2 0.00036 0.83 700.0 11.2 40.0 500.0 0.77 0.138 0.21 0.18 0.073 0.60
Odor Index 100%
Recognition
-- 7,575
113,000,000 622,891 1,428 1,178 2,037 2,000 1,701 949 6,290 7,333 75,616 10,950
0,25 0.312 0.09 2.05 0,50 0.012 0.191 0.236 0.042
0.026
26,280
4,198 14,666
5,131 34,200 525,000 34,397 766,949
309
9,615
0.54
2,444
28.2
1,539
0.97
56,907
0.95
661,052
0.053
2,924,528
0.051
210,000
53.3 0.40
2,393 13,150
0.52
12,634
0.23
17,130
0.40
19,725
0.64 >5000.
4,109 -
No Odor Detected
at 5000.
(continued)
Quality
Sweet/Fruity Sweet Sweet/Ester Sour/Pungent Sharp/Ammoniacal Oleiinic Ammoniacal/Musty Sweet Sweet/Olefinic Husty/Sweet Musty Sweet Musty/Sharp Sweet/Aroraatic Sweet/Fruity
Ammoniacal Fruity/Acid Sweet/Alcohol Sweet/Musty Sweet/ESter Sweet/Musty Sweet Sweet/ESter Musty/Alcohol Goaty
Sharp Sharp/Musty Sweet/feter Ammoniacal/Amine Sweet Sweet Sour/Sharp Sweet/ISter Sweet/Alcohol Sour/Sharp Sweet/Alcohol Sweet/feter
\
Hedonic Tone
Unpleasant to Neutral Pleasant Pleasant Unpleasant Unpleasant Unpleasant to Neutral Unpleasant Unpleasant to Neutral Neutral Neutral Unpleasant to Pleasant Pleasant to Neutral Unpleasant Unpleasant to Pleasant Pleas ant
Unpleasant to Pleasant Pleasant Pleasant Unpleasant to Pleasant Pleasant Unpleasant to Pleasant Pleasant Pleasant to Unpleasant Unpleasant to Pleasant Unpleasant
Unpleasant to Pleasant UnpleasantPleasant to Unpleasant Unpleasant to Pleasant Pleasant Pleasant Neutral Pleasant Unpleasant to Pleasant Unpleasant to Neutral Pleasant Pleasant
U C C 100036
TABLE Z (continued)
Compound
Absolute ppm
Me thy let hand amine
1.0
Methyl Ethyl Ketone
2.0
2-Methyl-5-ethyl Pyridine
0.006
Methyl Isoamyl Alcohol
0.07
Methyl Isoamyl Ketone
0.012
^'Methyl Isobutyl Ketone
0.10
Methyl Methacrylate
0.05
2-Methylpentaldehyde
0.09
2-Methyl-1-Pentanol
0.024
^-Methyl Styrene
0.052
Morpholine
0.01
2,4-Pentanedione
0.01
n-Pentanol
0.21
2-Pi coline
0.014
n-Propanol
<0.03
Propionic Acid
0 .028
n-Propy1 Acetate
0.05
Propylene
22.5
Propylenediamine
0.014
PTopylene Dichloride
0.25
Propylene Oxide
9.9
Propionaldehyde
0 .009
Styrene
0.05
Styrene Oxide
0.063
Tetraethyl Ortho Silicate
3.6
--Toluene
0.17
Triethyl amine
<0.09
UCAR Solvent LM
0.7
(1 -Methoxy-2-Propanol)
UCON-11 (Trichlororaono-
5.00
fluoromethane)
UCON-113 Solvent (Trichloro - 45.0
trifluoroethane)
Valeraldehyde
0.0005
Vinyl Acetate
0.12
Vinyl Chloride
22.0
Vinyl Cyclohexene
0.008
Vinyl Norbornene
0.007
Xylene
0.08
50% Recognition
PPm
3.4 5.5 0.008 0.20 0.049 0.28 0.34 0.136 0.024 0.156 0.07 0.020 0.31 0.023 0.08 0.034 0.15 67.6 0.048 0.50 35.0 0.040 0.15 0.40 5.0 1.74 0.28 1.4
135.0
68.0
0.002 0.40 360.0 0.019 0.011 0.27
100% Recognition
ppm
3.4 6.0 0.010 0.20 0.070 0.28 0.34 0.136 0.082 0.156 0.14 0.024 0.31 0.046 0.13 0.034 0.15 67.6 0.067 0.60 35.0 0.080 0.15 0.40 7.2 1 .74 0.28 1.7
209.0
135.0
0.002 0.55 440. - 530. 0.029 0.026 0.27
Odor Index 100%
Recognition
388 15,350 137,200
6,600 75,142 70,357 119,705 131,571 24,024 16,020 65,857 384,166
4,258 114,347 246,625
91,500 218,666
14,792 218,000
87,096 16,600 4,346,000 44,391
3,420 341
16,609 253,571
84
54
220,000
-
29,222
Quality
Musty/Anunoniacal Sweet/Sharp Sour/Pungent Sweet/Pungent Sweet/Sharp Sweet/Sharp Sweet/Sharp Sweet/Rancid Sweet/Alcohol Sweet/Aromatic Fishy/Amine Sour/Rancid Sweet/Alcohol Sweet Sweet/Alcohol Sour Sweet/Ester Aromat ic * Sharp/Amine Sweet Sweet Sweet/Ester Sharp/Sweet Sweet Sweet/A1cohol Sour/Burnt Flshy/Araine Ether/Sweet
Sweet
Sweet
Sour Sour/Sharp Sweet/Rubber Sour Musty Sweet
New Compound Additions
*'
Hedonic Tone
Unpleasant Neutral to Unpleasant Unpleasant Pleasant Pleasant Pleasant to Unpleasant Unpleasant Unpleasant Pleasant Pleasant Unpleasant Unpleasant Pleasant Unpleasant Pleasant Unpleasant Pleasant Neutral to Pleasant Unpleasant Pleasant Neutral to Pleasant Pleasant Unpleasant Pleasant Pleasant Unpleasant to Neutral Unpleasant to Pleasant Pleasant
Pleasant to Unpleasant
Pleasant to Unpleasant
Unpleasant Unpleasant Pleasant Pleasant Pleasant Neutral to Pleasant
UCC 100037
Table I. Odor thresholds in air (ppm volume).
Chemical
Odor Threshold
Odor Description*
Acetaldehyde Acetic acid Acetone Acrolein Acrylonitrile Allyl chloride Amine, dimethyl Amine, monomethyl Amine, trimethyl
Ammonia Aniline Benzene Benzyl chloride Benzyl sulfide Bromine Butyric acid Carbon disulfide Carbon tetrachloride (chlorination of CSi) Carbon tetrachloride (chlorination of CH,) Chloral Chlorine Oimethylacetamide Dimethylformamide Dimethyl sulfide Diphenyl ether (perfume grade) Diphenyl sulfide Ethanol (synthetic) Ethyl acrylate Ethyl mercaptan Formaldehyde Hydrochloric acid gas Hydrogen sulfide (from NaiS) Hydrogen sulfide gas Methanol Methyl chloride
Methylene chloride Methyl ethyl ketone Methyl isobutyl ketone Methyl mercaptan Methyl methacrylate Monochlorobenzene Nitrobenzene Paracresol Paraxylene Perchloroethylene Phenol Phosgene Phosphine Pyridine Styrene (inhibited) Styrene (uninhibited) Suttur dichloride Sulfur dioxide Toluene (from coke) Toluene (from petroleum) Tolylene diisocyanate Trichloroethylene
0.21 1.0 100.0 0.21 21.4 0.47 0,047 0.021
0.00021 46.8
1.0 4.68
0.047 0.0021 0.047 0.001 0.21 21.4 100.0 0.047 0.314 46.8 100.0 0.001 0.1 0.0047 10.0 0.000470.001 1.0 10.0 0.0047 0.00047. 100.0 rove 10 ppm)
214.0 10.0 0.47 0.0021 0.21 0.21 0.0047 0.001 0.47
4.68 0.047 1.0 0.021 0,021 0.1 0.047 0.001 0.47 4.68 2.14 2.14 21.4
Green sweet. Sour Chemical sweet, pungent Burnt sweet, pungent Onion-gailic-pungency Garlic-onion pungency,"green Fishy Fishy, pungent Fishy, pungent Pungent Pungent Solvent Solvent Sulfidy Bleach, pungent Sour Vrpet.iblc sulfide Sweet, pungent
Sweet Bleach, pungent Amine, burnt, oily Fishy, pungent Vegetable sulfide
Burnt rubbery
Sweet
,
Hot plastic, earthy '
Earthy, sulfidy
Hay/straw-like, pungent
Pungent >
Eggy sulfide
Sweet
Sweet Sweet Sulfidy, pungent Pungent, sulfidy Chlorinated, moth balls Shoe polish, pungent Tar-like, pungent Sweet Chlorinated solvent Medicinal Hay-like Oniony, mustard Burnt, pungent, diamine Solventy, rubbery Solventy, rubbery, plasticy Sulfidy
Floral, pungent, solventy Moth baits, rubbery Medicated bandage, pungent Solventy
" Other than chemical name
all ntuii'li.'l' recognize the odor. All concentrations am calculated as [tarts per million l>y volume. The minimum thrC'-hol'l oh-ervctl was with trimethyl amine at 0.00021 ppm (0.21 ]>pb). Me.thylene. chloride was not dereribed below a concent rat inn of 214 ppm. The 53 compounds studied represent a rattle of six orders of magnitude in threshold concentrations (Table I). Odor de scriptions (oilier than chemical name) used to de'eriltc the odor quality of the odorant eheiuieal are included ill Table I.
Sulfur Containing Compounds
Asa jtroup, compounds with the sulfur atom m their structure have the lowest thresholds of the compounds evaluated (Table II). All the sulfides with the exception of carbon disulfide and sulfur dioxide have threshold concentrations at the parts per billion level.
Hydrogen sulfide gas from a cylinder exhibited a lower threshold than hy drogen sulfide gas produced by acidify ing sodium sulfide. The discrepancy' in the determined odor threshold for the two hydrogen sulfide samples may be due to impurities that arc present in the samples used; further studies arc 1icing pursued to determine the factors ac counting for this discrepancy tatween samples. ]t is of interest that carbon disulfide, sulfur dichloride, and sulfur dioxide affect the other chemical senses (taste and fee!) ns well as having odorous effects.
Nitrogen~Cont*tnfng Compounds
Of the 53 odorant chemicals eval uated, trimethyl amine exhibited the lowest threshold (0.00021 ppm). Di methyl formamido is recognizable at 100 ppm. The nitrogen-containing compounds indicate the wide range of threshold concentrations that can occur
(Table fir).
Oxygenated Compound*
Table IV lists the odor thresholds of oxygenated eom|>ounds according to chemical class. Extent of oxidation of the ethanol scries (ethanol, acetalde hyde, acetic acid) does not np[>ear to have an affect on the odor threshold trend. One might expect a lower threshold as the oxidation state is in creased. Chloral (trichlorinated anatnof acetaldehyde) does have a substan tially lower threshold (0-047 ppm) than
Table II. Odor thresholds -- sulfur com pounds (ppm volume).
Table III, Odor thresholds -- nitrogenous compounds (ppm volume).
acetaldehyde. Considering other chlo rine-containing compounds studied, it is
Hydrogen sulfide (cylinder) Dimethyl sulfide Ethyl mercaptan Sulfur dichloride Benzyl sulfide Methyl mercaptan Hydrogen sulfide (Na,S) Diphenyl sulfide Caibon disulfide Sullur dioxide
0.00047 0.0010 0.0010 0.0010
0.0021 0.0021 0.0047 0.0047 0.21 0.47
Trimethyl amine Nitrobenzene Monomethyl amine Pyridine Dimethyl amine Aniline Acrylonitrile Ammonia Dimethyl acetamide Dimethyl formamide
0.00021 0.0047 0.021 0.021 0.047 1.0 21.4 46.8 16,8 100.0
not possible to make a generalization ns to tbeVffcet of chlorination on the odor threshold.
Unsaturated Compound*
The presence of unsnturation in an odorant chemical is not associated with low threshold concentrations (Table V). Ethyl acrylate and methyl methacrylate arc isomeric, however, the threshold concentrations are quite different. The
LJl--.lv.>,. m 1 a
UCC 100038M Journal of the Air Pollution Control Association
Valjts IV. Odor thresholds -- oxygenated compounds (ppm volume).
Carbonyls Chloral Acetaldehyde Acrolein Methyl isobutyl ketone Phosgene Formaldehyde Methyl ethyl ketone Acetone
Esters Ethyl acrylate Methyl methacrylate
Carboxylic Acids Butyric acid Acetic acid
Alcohols p-Cre$ol Phenol Ethanol Methanol
0.047 0.21 0.21 0.47 1.0 1.0 10.0 100.0
0.00047 0.21
0.001 1.0
0.001 0.047 10.0 100.0
Tablet/. Odor thresholds -- variously substituted ethylenic compounds (ppm volume).
Chemical
Odor Thresh R Group(s) olds
Ethyl acrylate
-C:OOC,H, 0.00047
Styrene
--C.Hj
0.047
Acrolein
--HC:0
0.21
Methyl meth acrylate
--CH..
0.21
--CiOOCH.
Allyl chloride
--CHvCI
0.47
Tetrachloroethylene --C1(4X)
4.68
Trichloroethylene --CI(3X)
21.4
Acrylonitrile
C=N
21.4
Table VI. Odor thresholds -- variously substituted benzenoid compounds (ppm volume).
Chemical
Odor ThreshR Group(s) old
Paracresol Nitrobenzene Phenol Benzyl Chloride Styrene Monochlotobenzene p-Xylene Aniline Toluene Benzene
--OH, --CH. --NO, --OH --CH;CI --CH.CH,
-Cl --pCHt --CHi --NH. --CH,
0.0010 0.0047 0.0470 0.0470 0.0470 0.21 0.47 1.0 2.14 4.68
Table V||. Odor thresholds of chemicals purified by GLC.
Tolylene diisocyanate Tolylene diisocyanate*
Toluene (coke) , Toluene (coke)* Toluene (petroleum)
Styrene (WUbited) | Styrene (inhibited)*
Styrene (uninhibited)
2.14 ppm 2.14 ppm
4.68 ppm 2.14 ppm 2.14 ppm
0.10 ppm 0.21 ppm 0.047 ppm
PufMac-d by GLC pfoc**dirrf
Fotyuary 1969 Volume 19. No. 2
mlor (lt`'cn|iininMl,i difTi-r ^Mv Table I). This disparity points up thn difficulty of making extended generalizations jn-rtainiitg to the odor threshold based on similar chemical >l pictures.
Benzenoid Compounds
The effect of substitution on ihn benzene ring also prod tires a aide. v:ti iatiou in odor thresholds Table VI.
A single nieth\lation of the benzene ring (toluene) lowers the threshold one concentration step. Further modula tion (p-xyienc) siiccecd.s in lowering the odor threshold by an order of magnitude. The --Clb.-Cl dump (benzyl chloride) produces an odor threshold that is 100 times lower than benzene. The only generalization possible with benzenoidtyi>c materials is that, substitution on the ring reduces the odor threshold by as much as a thousandfold depending on the nature of the group added.
Purity of the Chemical
Odor thresholds of samples purified by gas licptid chromatography -how slight differences, if any, from the start ing material. With Inlyienr diisocyauatc, the prime effect of the purifica tion appears to climmalc or reduce -ob sidian" odor character notes and leaves a sharper odor impression of the prime odor character note. bi this ease, purification did not affect the lerognition threshold. Table VII lists the odor thresholds of chemicals licforr and after purification.
Toluene (from coke) purified chromatographieally has a slighly lower odor threshold; styrene, however, on purifica tion showed a higher odor threshold. Samples of carbon tetrachloride and toluene representing different tmules of manufacture do show variation in the odor threshold concentration ( Table I). Carbon tetrachloride manufactured by the chlorination of earhon disulfide has a lower threshold (HI.-I ppm) than carbon tetrachloride produced by the chlorina tion of methane (100 ppm). 'Toluene produced from coke has a slightly higher threshold concentration (4.fiS ppm) than toluene prod need from petroleum (2.H ppm). 'The odor character notes (Table 1) iNcd to dcscrihe the two sam ples reflect the difference in mode of manufacture. 'The purity of the chemiral can effort the odor (piality as well as the mlor threshold. Thus it is difficult to predict with any certainty the role that impurities present in the compound may play in affecting the odor threshold.
Conclusions
Recognition odor thresholds have been determined in the laboratory by an expert panel for 53 commercially im portant chemicals. By standardizing the method of sample presentation and minimizing extraneous sensory inteifcrence, the concentrations determined as producing the minimum identifiable
UCC 100039
odor le-poii-e provide consistent and internally comparable data for one parameter of odor. The-e recognition threshold concentrations demonstrate the broad range in sensitivity of human olfaction to various chemical structures under ideal test conditions.
It should be noted that, in addition to the threshold concentration for a giwn chemical compound, there are at least three sensory attributes and two psychological parameters to be con sidered in evaluating its contribution to odor problems. The three -en.sory attrilmtesare: (I) the change in intensity (odor strength) with concentration; (2) the qualitative character of the odor; and (3) thn type and degree of interaction with other odorants. Psy chologically, people react either jositiveiy or negatively to odor types -- they like or dislike them. A problem is usually associated with those that people dislike. .Secondly, people react mine strongly to thing- that are differ ent and, therefore, what is normal or expected is frequently accepted be it good or bad.
'The work discussed in this paper is a first step in providing basic informa tion on a number of chemicals which arc industrially important. The recog nition odor thresholds reported in this study were developed under ideal !al>nratory conditions and are not rernmmeudod for air (piality criteria and standards since no effort was made to define the degree of ohjoctionuhility of the odorant chemicals. Future phases of this program will attempt to provide data on the other aspects of the problem, sucli as the method of sample presenta tion, the* use of untrained observers, the change in intensity (and (piality) with concentration, and the odor interactions with typical impurities.
Studies arc presently 1icing conducted to determine and compare the odor thresholds of selected chemicals ob tained from various methods of odor presentation. These include the syringe dilution method and a dynamic (odor hood) method of odor presentation. In addition, the effect of varying types ami levels of background odor on the recognition odor threshold arc being evaluated.
References
1. Adams, K. M., "Air Pollution Abate ment. Manual--Physiological Effects,'' (loslinc, ed., 22-26, Ch. 5, ManuTU Sheet p. 6, Manufacturing Chemists' Assoc., Washington (1951)
2. Sjiistriim, L. B., Cftirncross, S. E., and Caul, J. F,, "Methodology of the flavor profile," Food Tech. XI, 20, (1957)
3. Mainer, It, M., Emslie, A. G., and Jacobson, A., "An information theory of olfaction," Annals N.Y. Acad, of Sci. 58, 158-173 (1054) ^
4. I>rinirigrr, N., and McKinley, R. W,, ""The design, construction, and use of an odor test room," ASTM, Sp. Tech, Publ. No, 104 (1054),
95
