Odor Thresholds and Irritation Levels of Several Chemical Substances: A Review

JON H. RUTH

Wausau Insurance Companies, 550 California Street, San Francisco, CA 94120.

A collation of odor threshold data ,for approximately 450 chemical substances is presented. The range of odor thresholds reported in the literature is showlfalong with any reported threshold of irritation to humans. Th~se data can assist the industrial hygienist in determining . when an "odor"may be in excess of the Threshold Limit Value®, when an organic vapor respirator is not acceptable due to the lack of an odor warning at the end of a cartridge life, and where odors may not indicate a hazard due to extremely low odor thresholds which may be well below the respective TLVs.

Introduction

Although the sense of smell cannot be relied upon to evalu­ should allow the industrial hygienist to interpret the odor ate the hazards of chemicals used in the workplace, the with a proper sense of caution. A description of the odor and industrial hygienist can use the odor threshold of a chemical the threshold of irritation are also presented. The TLVs, in the recognition phase as a rough estimation of airborne available in the computer data base, have not been included concentration. The purpose of this effort is to gather in Table I since they are not directly used in this format for together, in one listing, the odor threshold and irritation the data. level data published in several less accessible formats. The range from the lowest reported odor threshold to the highest reported odor threshold is reported. A brief review of the History information available on our sense of smell and odors is In early times, Plato categorized odors as either pleasant or presented along with a short review of several methods of unpleasant. Several centuries later, Linnaeus, a Swedish defining a threshold of odor. Through an understanding of scientist, proposed seven odoriferous qualities: I) aromatic, , how the odor data have been developed ,and knowing the 2) fragrant, 3) musky, 4) garlicky, 5) goaty, 6) repulsive, and 7) range of odor thresholds, the industrial hygienist can use nauseous. A 20th Century Dutch physiologist added ethe­these odor thresholds intelligently as a tool in the recogni­ real (fruity) and empyreumatic (b1.!rnt organic matter) plus tion of potential hazards. several subdivisions to the previous classifications.(26) In "

those early times, the research consisted of categorizing Methodology various chemicals based on the description of their odor The odor thresholds and irritation levels.of several hundred quality. More recent research has concentrated on determin­chemicals were taken from the industrial hygiene literature(l-lO) ation of the odor threshold, or the quantitative amount of and other compilations of odor threshold data.(1l-24) The chemical in air which can be detected by the human sense of odor thresholds were recorded as a range from the lowest to smell. the highest concentration reported. Whenever information was discovered with a reported odor threshold lower or higher than the current data base range, the appropriate Physiology of Smell

value was changed. The concentration level where irritation For a person to smell something, air containing odoriferous begins was recorded where available. Subjective descrip- molecules must reach a tiny cluster of specialized nerve cells tions of the odors were also included where they have been well inside the nasal cavity. These nerve cells, the olfactory determined. Finally, the American Conference of Govern- neurons, are at the top of the nose, just above the bridge, mental Indust,/~ial Hygienists - Threshold Limit Value(25) was

;-<,~and are positioned out of the major airstream. Each nasal added to th~' comput¢r data base where a TLV has been cavity has about five million ofthese receptors which are the assigned; These data w,kreentered into a personal computer only nerve cells in the body which have the ability to regen­database program (Apple II+ using DB Master software) erate. Inhaled air first passes across a series of small bones, for manipulation (conversion of ppm data into mg/ m3

), the turbinates, which create turbulence and cause a sm.all alphabetization and custom report generation (e.g., poten- amount of air to reach the odor receptors. Sniffing creates tial for separation ~f chemicals into groiJps with odors below strong eddy currents that force more air into the upper the TLV vs. those with odors above the TLV)., portion of the nose and greatly increases the sense of

In Table I, the data are presented in alphabetical order smell.(17,26) Together with the actual flow rate of the air in the with both the lowest and highest thresholds given in mg/ m3

• nose, it has been shown that air temperature and relative The range of odor thresholds reported for a given chemical humidity also affect the perception of odors.(21)

Copyright 1986, American Industrial Hygiene Association

Am,Am, Ind, Hyg, Assoc, J. (47) March, 1986 A-142

'1 The ten million olfactory neurons can perceive some 4000 ifdifferent odors.(17) A Yale University study has shown that 4the average person can correctly name only a handful of ~~'common odors. This limitation, however, seems to be a ~result of an inability to think of the name of the substance .\1~ rather than a failure t~~ detect the differences between the 10dors.(26) Although women are not better able to detect ~i odors than men, they are more a ware of the odor environ­illlent and can identify more odors than men.(26) Constant

. ;;f ~xposure to odors can ind uce non-perception as the olfac­f tory neurons become fatigued. People tend to become accus­,;' tomed to odors, even those which they initially find unpleas­c' ant. Two different odors presented simultaneously can be

distinguished from one another if their characteristic odors are sufficiently different from each other. Chemicals used to mask odors can eventually be detected separately from the odor these chemicals were supposed to be masking.

i' t'f €~ Determination of Threshold

The method of defining and determining the threshold of odor varies widely, giving rise to a significant range from low to high in the odor thresholds reported. A wide variation in threshold definition, sample presentation, panel selection, purity of chemicals used and data interpretation have resulted in data that seem to lack consistency. (21)

A classical definition of odor threshold is the minimum concentration of an odorant which produces a noticeable change in the odor of the system.(21) The threshold is often designated as the lowest concentration perceived after no anomalies OCCUr.(27) Common anomalies are the perception of an odor when a blank or zero concentration sample is presented and not perceiving an odor at a concentration

higher than that at which an odor was previously noticed. Another definition sometimes used is the recognition odor threshold: the minimum concentration at which the odor quality (description of smell) of the compound can be de­scribed. Minor differences in concentration are beyond olfac­tory discrimination. It takes approximately a 30% to 60% increase in the concentration to allow the subject panel to consistently identify the higher concentration as higher.(17,21)

Samples may be presented in several fashions. Most simply, the odor concentrations may be presented in simple order of increasing concentration from zero to the concen­tration level first perceived. Another protocol randomly mixes blanks, or zero concentration samples, in with the odor samples which are presented otherwise in simple order of increasing concentration. These presentations in order of increasing concentration are called serial tests.(28) Finally, the odor concentrations may be presented in a random fashion to minimize any sample order bias. Where odor recognition is the definition of the threshold, a triangle test is used most often, in which two odors are presented and compared.(2o.28) Panel selection ranges from trained "sniffers" to the general population. A quick sniff of the sample yields a better perception of the odor than a slow, even inhalation. Trained "sniffers" would understand how to sniff for the odor and be more experienced in describing the quality of the odor.

Data may be interpreted in several different ways. The odor threshold may be set at the lowest concentration per­ceived by a single subject (absolute threshold), which, of course, would yield the lowest concentration of an odor threshold. Other researchers determine the threshold as that concentration where 50% of the test subjects notice the odor

TABLE I Odor Thresholds and Irritation Concentrations of Chemicals

Chemical Compound

Acenaphthene Acetaldehyd.e Acetic acid Acetic anhydride Acetone Acetonitrile Acetophenone Acetyl acetone Acetylene Acrolein Acrylic acid Acrylonitrile Aldrin Allyl alcohol Allyl Alcohol (N-) Allyl amine Allyl chloride Allyl disulfide Allyl glycidyl ether Allyl isocyanide Allyl isothiocyanate Allyl mercaptan Allyl sulfide Ammonia

Am. Ind. Hyg. Assoc. I (47) March, 1986

Odor.Low Odor High Description Irritating mg/m" mg/m" of Odor Cone. mg/m"

0.5048 0.5048 0.0002 4.1400 Green, sweet, fruity 90.00 2.5000 250.0000 Sour, vinegar-like 25.00 0.5600 1.4400 Sharp odor, sour acid 20.00

47.4666 1613.8600 Minty chemical, sweet 474.67 70.0000 70.0000 Ether-like 875.00

0.8347 2.9460 Sweet, almond 0.0409 0.0409

657.2000 657.2000 0.0525 37.5000 Burnt, sweet 1.25 0.2820 3.1200 Rancid, sweet 8.1000 78.7500 Onion-Garlic pungency 0.2536 0.4027 1.9500 5.0000 Pungent, mustard 12.50

150.0000 150.0000 14.5080 14.5080 187.20

1.4100 75.0000 Green, garlic, oniony 75.00 0.0005 0.0005 38.06

44.0000 44.0000 Sweet 1144.00 0.0610 5.4240 Sweet, repulsive 17.02 0.0325 1.7052 Mustard oil 17.05 0.0002 0.0515 Garlic-like 454.50 0.0007 0.0007 6500.64 0.0266 39.6000 Pungent, irritating 72.00

A-143

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ODOR THRESHOLDS AND IRRITATION LEVELS: A REVIEW

TABLE I Odor Thresholds and Irritation Concentrations of Chemicals

-I ::r CD

3 III CD ~ 0 =' 50. iii' "0 III to CD

::E III IJl

8,"2. , ~ _I a 3 50 CD ()

Q. CD ()

0"'"

-=' 0

50 CD z ~ 0 =' Q!.

r ­5' iii -< 0-s: CD 0..

5: =' CD cr '< III

50 a "0 III ;:+'< III =' 0..

3 III '< cr CD "0

a CD ()

CD 0.. cr '< c 0 0 0 "0 '< ~.

;:r iii ::E

Chemical Compound

Carbon tetrachloride from CH,

Caryophyllene Cellosolve Cellosolve 'acetate Cellosolve solvent Chloral Chlordane Chlorinated Camphene

Toxaphene Chlorine Chlorine Dioxide Ch loroacetaldehyde Chloroacetophe none (alpha-) Chlorobenzene

Odor Low mg/m3

300.0000

0.5350 2.0350 0.3024 1.1040 0.2825 0.0084 23689

0.0300 0.3000 3.0000 0.1020 0.9800

Odor High Description mg/m" of Odor

1500.0000 Sweet, pungent

0.5350 185.0000 270.0000 Sweet, musty

2.0240 0.2825 Sweet 0.0419 2.3689

15.0000 Bleachy, pungent 0.3000 Sharp, pungent 3.0000 Sharp, irritating 0.1500 Sharp, irritating

280.0000 Sweet, almond-like

Irritating Cone. mg/m3

9.00 15.00 3.00 0.05

933.33 Chlorobenzylidene malonitrile (ortho-) Peppery 1.52 Chlorobromomethane Chloroform Chlorophenol Chloropicrin Chlorotoluene Citral Coumarin Cresol Crotonaldehyde Cumene Cyanogen Cyanogen chloride Cyclobutylamine Cycloheptylamine Cyclohexane Cyclohexanol Cyclohexanone Cyclohexylamine Cyclopentadiene Cyclopentyl acetate Cyclopentylamine Cyclopropylamine OOT Decaborane Decalin Decanoic acid Decanol Diacetone alcohol Diacetyl Diallyl sulphide Dibenzofuran Diborane Dibromo-3-chloropropane (1,2-) Dibutylamine Dibutylamine (N-) Dichloroacetic acid Dichloroanisole (2,6-) Dichlorobenzene (ortho-) Dichlorobenzene (para-) Dichloroethane Dichloroethyl ether Dichloroethylene (1,2-) Dichlorophenol (2,4-) Dicyclo pentadiene Diethyl disulfide Diethyl ethanolamine Diethyl ketone Diethyl pyrazine (2,5-) Diethyl selenide

2100.0000 250.0000

0.0189 5.4600 0.2350 0.3738 0.0020

0.0012 0.1050 0.0392

500.0000 2.0000

97.1750 309.2600

1.4350

2100.0000 Sweet 1000.0000 20480.00

6.5224 Medicinal, empyrumatic 6801.18 7.7000 Sharp, penetrating 2.10 0.2350 Pungent, irritating 0.3738 0.0120 Pleasant, vanilla

22.0000 Sweet, creosote, tar 3.0000 Pungent, suffocating 23.01 6.3700 Sharp, aromatic

500.0000 Pungent 32.00 2.0000

340.8600 573.4000

1.4350 Sweet, aromatic 1050.00 400.0000

0.4800 106.0000

5.0667 0.1031

676.4000 153.5170

5.0725 0.3600

565.0000 11.9510 0.0006 1.3440 0.0035 0.0005 0.7752 2.0000 0.0965 0.4224 0.4232 1.2144 0.0003

12.0000 90.0000

445.5000 90.0000

0.3358 1.4007 0.0297 0.0195 0.0536 3.1725 0.0336 0.0617

400.0000 400.0000 448.0000

5.0667 0.1031

2278.4000 153.5170

5.0725 0.3600

565.0000 112.4800

43.2820 480.0000

0.0880 0.1491 1.6150 4.0000 0.2895 1.4256 2.5392 1.2144 0.0003

300.0000 180.0000 810.0000

2160.0000 1975.0000

1.4007 0.0540 0.0195 0.1948

49.3500 0.1120 0.0617

Camphor-like 200.00 Sweet, pepperminty 100.00

565.00

Sweet 240.00

Garlicky

Repulsively sweet 1.93

Fishy, amine

150.00 Mothballs 240.00 . Chloroform-like

600.00 Acrid, eth.ereal

Sharp. sweet 2.70

Amine

Putrid

Am. Ind. Hyg. Assoc. 1. (47)

TABLE I (cont.)

Odor Low Odor High Description Irritating Chemical Compound mg/m" mg/m" of Odor Cone. mg/m.l

Amyl acetate (N-) 00265 371000 Fruity, banana, pear 530.00 Amyl acetate (sec-) 0.0107 00107 Amyl alcohol (iso-) 25.2000 25.2000 Amyl alcohol (N-) 04332 72.2000 Sweet Amyl alcohol (tert-) 0.8303 0.8303 Amyl amine (N-) 566G40 132.0760 Amyl mercaptan 0.0001 0.0018 Amyl mercaptan Oso-) 0.0018 0.0018 Aniline 0.0002 350.000d Pungent, amine-like Anisole 0.2210 0.2210 Apiole 0.0570 0.0570 Arsine 0.8400 2.0000 Garlic-like Azelidine 51.9200 169.9200

= -l Azine 31.6480 66.2400(1)

Azole 134.2600 295.9200 t\) Benzaldehyde 0.0008 0.1823 Pleasant, bitter 20.01 3 'iii'

Benzene 4.5000 270.0000 Sweet, solventy 9000.00~ Benzene hexachloride 0.0015 142.8000

::l Benzenethiol 0.0012 279.0000 Benzothiazole 04424 2.2120 Benzyl chloride 0.2350 1.5500 Solventy 41.00 Benzyl mercaptan 0.0132 0.2028 Unpleasant 22.81 Benzyl sulfide 0.0184 0.0184 Sulfidy Biphenyl 0.0062 0.3000 750 Boron trifluoride 4.5000 4.5000 Pungent, irritating Bromine 0.3290 24.5000 Bleachy, penetrating 2.10 Bromoacetophenone 0.1221 1.3838 Unpleasant 0.33 Bromochloromethane 16800000 1680.0000 Bromoform 5300.0000 5300.0000 Similar to chloroform Butadiene (1,3-) 0.3520 2.8600 Butadiene dioxide 176000 17.6000 35.20 Butane 2.8500 14.6300 Butenethiol (2-) 0.0001 0.0001 Butyl acetate (iso-) 0.0090 90.0000 Pleasant, fruity 1350.00 Butyl acetate (N-) 33.1333 94.6666 Fruity 473.33 Butyl acrylate Oso-) 0.0110 0.0660 Sweet, musty Butyl alcohol (iso-) 0.3600 225.0000 Mild, non-residual 300.00 Butyl alcohol (N-) 0.3600 150.0000 Sweet 75.00 Butyl alcohol (secondary-) 131.1500 131.1500 Strong, pleasant Butyl alcohol (tertiary-) 219.0000 219.0000 Camphor-like Butyl amine (N-) 0.2400 6.0000 Ammonical 30.00 Butyl celloso/ve 0.4800 288.0000 Sweet, ester Butyl cellosolve acetate 0.7194 1.3080 Sweet, ester Butyl chloride (N-) 3.3352 6.3293 Pungent Butyl ether (N-) 0.3731 2.5051 Fruity, sweet Butyl formate 70.8900 834000 Butyl furan (2-) 50.8000 50.8000 Butyl lactate (N-) 35.0000 35.0000 Butyl mercaptan 0.0016 00033 Stinks!

a Butyl sulfide 0.0897 0.0897

0

"'0 t\) Butyl toluene (P-, tertiary-) 300000 30.0000 Gasoline-like 48.00

Butylamine 3.0000 378.0000 Ammonia, fishy 30.00 t\) Butylene 54.9600 54.9600 Gassy ~ ::l a. Butylene oxide 0.2058 2.0874 Sweet, alcohol 3 t\) Butylthiazole (2, iso-) 0.0202 0.0202 '<0- Butyraldehyde 0.0136 26.5500 Sweet, rancid ct> Butyric acid 0.0010 9.0000 Sour, perspi ration

"'0 Butyric acid Oso-) 29.1600 29.1600a

m: Camphor (synthetic) 7.8000 1200.0000 10.62n, 'iii' Caprolactam 28.0000 28.0000 0.,

Capryl alcohol Sweet, pungentrr '< Carbitol 1.1508 6.0280 Sweet, mustyC

Carbitol acetate 0.1872 1.8936 Sweeten• I

Carbon disulfide 0.0243 23.1000 Disagreeable, sweetO. 0

"'0 Carbon tetrachloride 60.0000 128.4000 Sweet, pungent ~ from CS2cO' ;r

. Hyg Assoc. J (47) March, 1986 '~ A-145

g.

ODOR THRESHOLDS AND IRRITATION LEVELS: A REVIEW

TABLE I (cont.)

Chemical Compound

Diethyl sulphide Diethyltrisulfide Diethylamine Diglycidyl ether Diisobutyl carbinol Diisobutyl ketone Diisopropyl amine Dimethoxy dimethyl pyrazine Dimethyl acetamide Dimethyl amine Dimethyl disulfide Dimethyl ethanolamine

-t Dimethyl formamide (N,N-)::T CD Dimethyl napthalene3 Q) Dimethyl sulfide

~ Di methyl trisulfide ![ Dimethyltrithiocarbonate 0 Dimethylacetamide (N,N-)::J

5' Dimethylamine00' Dimethylformamide (N,N-)"0 Q) Dimethylhydrazine (1,1-)co CD Dioxane (1,4-) ::E Q) Dioxane (para-) en ("): Dioxolane (1,3-)0, "0 DipenteneCD' Co Diphenyl ether (perfume) =r i Diphenyl sulfide 0 3 Dipropylamine 5' Dipropylamine (N-)CD (") Dipropylene glycol methyl ether Q. Dodecanol (1-)CD (") Dodecyl Mercaptan (N-)g ::J Dowtherm A 0 Endrin-5' EpichlorohydrinCD

Ethanez Q) Ethanolamine= 0 ::J Ethoxy 3,4 dihydro 1,2 pyran (2-) Q!. Ethoxy 3,4-dihyro 1,2 pyran r cr Ethyl acetate ill Ethyl acrylate ~

-0 Ethyl alcohol (synthetic) Ethyl amine

~ CD Ethyl amyl ketoneCon' Ethyl benzene S' CD Ethyl benzoate

'<cr Ethyl bromide Q) Ethyl butanol (2-) 5' Ethyl ether a "0

Ethyl formate Q) Ethyl hexanol (2-) Q­Q)

Ethyl hexyl acetate ::J Co Ethyl hexyl acrylate (2-)

Ethyl isothiocyanate3 Q) Ethyl lactate '< cr Ethyl mercaptan CD "0 Ethyl methyl disulfide <3 Ethyl methylamineCD (") Ethyl morpholine (N-)CD Co Ethyl phenylacetate cr Ethyl propyl amine'< c Ethyl selenide 0 Ethyl selenomercaptan 0 0 Ethyl silicate "0 Ethyl su Ifide ~ ciS' ~ Q) ::;:

Odor Low mg/m'

0.0177 0.0044 0.0600

25.0000 0.1885 0.6600 0.5200 1.2366

161.0000 0.0846 0.0001 0.0546

300.0000 0.0428 0.0025 0.0062 0.0331

163.8000 0.0378

300.0000 12.0000 0.0108

20.1600 44.5400

0.6950 0.0026 0.0826 0.4140

210.0000 0.0152

4222.8000 0.7000 0.2808

50.0000 184.5000

5.3333 3.1440 0.1048 0.0196 0.0008 0.3420 0.4860

31.2000 8.7000 3.8068

890.0000 0.2919 0.9900

0.3990 0.5132 0.5497 6.0520

67.6200 3.2 x 10-5

0.0487 21.6900

0.3680 4.3615

60.5200 0.0003

8.0 x 10-6

722.5000 0.0009

Odor High Description Irritating mg/m"

0.0117 0.0044

114.0000 25.0000

0.9424 1.8600 3.4000 1.2366

163.8000 0.0846 0.3465 0.1638

300.0000 0.0428 0.0508 0.0062 0.0331

of Odor Cone. mg/m"

Foul, garlickly

Fishy, ammonical 150.00 50.00

Sweet, alcohol Sweet, ester 150.00 Fishy, amine 100.00

174.60

Amine

Decayed cabbage

163.8000 Amine, burnt, oily 55.8000

300.0000 20.0000

612.0000 972.0000 335.3600

0.6950 0.0358

227.1500 0.8280

6000.0000 0.0533

4222.8000 7.0000 6.3963

80.0000 1105.7700

10.6666

Fishy, ammonical Fishy, pungent Ammonical, amine-like Ether-like

Sweet, musty Lemon-like Pleasant, geraniums Burnt, rubbery Ammonical, amine Ammonical, amine Ether-like

792.00 720.00

450.00

Aromatic, disagreeable 21.00

Chloroform-like 325.00

Ammonia 13.33 3.1440 Sweet, fruity 3.1440

665.0000 32.0000

9690.000 396.0000

31.2000 870.0000

3.8068 890.0000

3.2109 3.0000

0.7342

Sweet, fru ity Fruity, pleasant 350.00 Earthy, acrid, plastic 16.00 Sweet, alcoholic 9500.00 Sharp, ammonical 180.00 Mild, fruity 260.00 Aromatic 870.00

Ether-like 28925.00 Musty, sweet Sweet, ether-like 300.00 Fruity 990.00 Musty

1.4763 Sweet 1.3554 6.0520

67.6200 0.0920 0.0487

79.5300 1.1500 4.3615

181.5600 0.003

0.0054 722.5000

0.0103

Sharp, musty Mustard, unpleasant 65.15

Garlic

Ammonia 184.00

Foul Alcohol-like, sharp 5950.00

Am. 1M Hyg. Assoc. J (47)

TABLE I (cont.)

Odor Low Odor High Description Irritating Chemical Compound mg/m3 mg/m3 of Odor Cone. mg/m3

Ethyl valerate 0.0266 0.0266 Ethyl vinyl ketone 0.0004 0.0069 Ethylene 299.0000 4600.0000 Olefinic Ethylene diamine 2.5000 28.0000 Ammonical, musty 250.00 Ethylene dibromide 76.8000 76.8000 Mild, sweet Ethylene dichloride 24.0000 440.0000 Sweet Ethylene glycol 62.5000 62.5000 Sweet Ethylene glycol dinitrate 0.18 Ethylene oxide 520.0000 1400.0000 Sweet, olefinic Ethylenediamine 25.0000 28.0000 Musty, ammonical 500.00 Ethyleneimine 4.0000 4.0000 Ammonical 200.00 Ethylidene norborene 0.0700 0.3650 Sweet, ~romatic 30.00 Fluorine 6.0000 6.0000 50.00 Formaldehyde 1.4700 73.5000 Pungent, hay 1.50 Formamide 150.0000 150.0000 Formic acid 0.0450 37.8000 Pungent, penetrating 27.00 Furfural 0.0240 20.0000 Almonds 48.00 Furfuryl alcohol 32.0000 32.0000 Glycol diacetate 0.5552 1.8626 Fruity, acid Heptachlor 0.3060 0.3060 Heptanal 0.0140 0.0932 Heptane 200.0000 1280.0000 Gasoline-like Heptyl alcohol (N-) 98.3250 98.3250 Heptyl isobutyrate 0.0989 0.0989 Heptyl propionate 0.0281 0.0281 Hexachlorobutadiene 12.0000 12.0000 Hexachlorocyclopentadiene 1.5000 3.3000 Hexadiene 1.6750 127.3000 Hexane (N-) 1800.00 Hexanol (1-) 0.0417 21.6840 Sweet, alcohol Hexyl acetate (secondary-) 0.0120 600.0000 Unpleasant 600.00 Hexyl isobutyrate 0.0422 0.0422 Hexyl propionate 0.0514 0.0514 Hexylene glycol 250.0000 250.0000 250.00 Hydrazine 3.0000 4.0000 Ammonical, fishy Hydrochloric acid 7.0000 49.0000 Irritating, pungent 49.00 Hydrofluoric acid 0.0333 0.1333 Strong, irritating 4.17 Hydrogen bromide 6.6667 6.6667 Sharp, irritating 10.00 Hydrogen cyanide 0.9000 5.0000 Bitter almond Hydrogen peroxide Slightly sharp 150.00 Hydrogen selenide 0.0016 12.0000 Decayed horseradish 6.00 Hydrogen sulfide 0.0007 0.0140 Rotten eggs 14.00 Iodine 9.0000 9.0000 2.00 Iodoform 0.0062 0.0833 Ionone 4.63 x 10-7 573.0500 Isoamyl alcohol 36.0000 126.0000 360.00 Isobutyl2-methoxypyrazine 13.5800 13.5800 Isobutyl 3-methoxypyrazine 1.3 x 10-5

9' a -c Q) ;::\. '< Q) ::J c.. 3

Isobutyl 3-methyl pyrazine Isobutyl butyrate Isobutyl mercaptan Isobutyl pyrazine (2-) Isodecanol Isopentanoic acid

0.2146 12.3690 0.0020 2.2080 0.1292 0.0209

0.2146 17.6700 0.0020 2.2080 0.2713 Musty, alc()hol 0.1084 Goaty

Q) '<

Isophorone 1.0000 50.0000 Sharp, objectionable 50.00 g, Isopropyl acetate 0.1900 1520,0000 Fruity 380.00

-c Isopropyl alcohol 7.8400 490.0000 Pleasant 490.00 a CD ~

Isopropyl amine Isopropyl ether

0.5040 0.0714

480.0000 Pungent, ammonia 1260.0000 Sweet, sharp, ether

24.00 1260.00

c.. Isopropyl glycidylether 1440.0000 1440.0000 0" '< Kerosene 0.5517 0.5517 122.60

c Ketene Sharp 41.40

0 Lauraldehyde 0.0151 0.0151 0 0 -c

Linalyl acetate Malathion

50.5260 13.5000

50.5260 13.5000

~ cO' Maleic anhydride 1.8400 1.9600 Acrid 5.48 ~

March. 1986 A-147

i 'II , il!1 ODOR THRESHOLDS AND IRRITATION LEVELS: A REVIEW

Chemical CompoundII Mercaptobenzothiazole

I" Mercaptoethanol Mesityl Oxide Methyl 2, cyanoacrylate Methyl acetate Methyl acetylene-propadiene

MAPP gas Methyl acrylate Methyl acrylonitrile (alpha-) Methyl alcohol Methyl amine Methyl amyl acetate Methyl amyl alcohol

=r -l CD Methyl anthranilate 3 Methyl benzyl alcohol

Methyl bromide :::!. Methyl butanol (2-) ~ *0 Methyl butenoic acid (2-) ::>

Methyl butyl acetate 9' 00' Methyl cellosolve "0 Methyl cellosolve acetatetil to CD Methyl chloride ::;;; Methyl chloroformtil en, Methyl cyclohexanen'0, Methyl cyclohexanol~" Methyl disulfide 0­

Methyl ethanolamine~ 0 Methyl ethyl ketone3

Methyl ethyl pyridine9" CD Methyl formate n Q. Methyl furan (2-) CD Methyl glycolg 0 Methyl heptanoate::> 0 Methyl hexyl ketone --.,

Methyl hydrazine9' CD Methyl iodide Z

Methyl isoamyl alcohol!a 0' Methyl isoamyl ketone ::> ~ . Methyl isobutyl'carbinol r Methyl isobutyl ketone6' 03 Methyl isocyanate-< Methyl isopropenyl ketone 0--., Methyl mercaptan:5::: CD Methyl methacrylate0-

Methyl n-amyl carbinol5: ::> CD Methyl n-amyl ketone cr Methyl n-propyl ketone'< til Methyl naphthalene (2-) 9' Methyl paratRion ~ Methyl pentaldehyde (2-) "0 til Methyl pentane (2-) ~ Methyl propanol (2-) til ::> Methyl propene (2-)0-

Methyl pyrazine (2-)3 til Methyl salicylate'< cr Methyl styrene (alpha-)CD "0 Methyl thiocyanate a Methyl vinyl ketone CD n MethylamineCD 0- Methylene chloride cr Methylene chlorobromide'< c Methylene glycol

0 Mineral spirits () Monochlorobenzene 0 "0 Morpholine'<:::!. to;or

A-148

TABLE I (cont.)

Odor Low mg/m3

12.0208 0.3828 0.0680 4.0000

610.0000 180.0000

70.0000 6.0000

13.1150 0.0252 0.4123 1.3761 0.0581

7235.5000 80.0000

0.0450 0.0528 0.0266 0.2880 1.6320

21.0000 542.8570

2000.0000 2350.0000

0.0012 3.0700 0.7375 0.0297

500.0000 90.4500

186.6000 0.0236

1299.5200 1.7500

0.2919 0.0576 2.0800 0.4100

1.0222 4.0 x 10'5

0.2050 0.0989 0.0940

28.0000 0.0581 0.1328 0.3681 0.2886 0.0027

45.8000 231.0000

0.6220 0.2496 0.7475 0.5720 0.0252

540.0000 2120.0000

76.2000 157.5000

0.9800 0.0350

Odor High Description Irritating mg/m3 of Odor Cone. mg/m3

12.0208 2.0416

100.0000 Sweet 100.00 12.0000 12.00

915.0000 Fragrant, fruity 30496.90 180.0000 Foul, objectionable

70.0000 Sharp, sweet, fruity 262.50 42.0000 6.00

26840.0000 Sweet 22875.00 12.0000 24.00

2.3560 Sweet, ester 2.1684 Sweet, alcohol 0.0581

5235.5000 4000.0000 Sweetish

0.8280 Sour, sharp 0.0528 Body odor 0.0266

288.0000 Mild, non-residual 368.00 240.0000 Sweet, ester 21.0000 Sweet, ethereal 1050.00

3800.0000 Chloroform-like 5428.57 2000.0000 Faint, benzene-like 2350.0000 Weak, coconut oil 2350.00

0.0039 10.4380 Musty, ammonical

147.5000 Sweet, acetone-like 590.00 94.0500 Sour, pungent

6875.0000 Pleasant 8750.00 90.4500

279.9000 0.0236

1299.5200 5.2500

21500.00 0.8340 Pungent 0.3360

200.0000 Sweat, mild odor 100.00 192.7000 Sweet, sharp 410.00

1.0222 0.0820 1.3940 0.3378 0.0940

45.5000 0.2905 0.1328 0.5562 0.2886 0.1303

45.8000 231.0000

0.8708 960.0000

0.7475 0.5720

12.0000

5.00

Sulfidy Arid, fruity, sulfidy 697.00 Sweet, alcohol

Sweet, rancid

Gassy

Sweet, aromatic 960.00 Sweet, unpleasant 480.19

Fishy, pungent 30.00 2160.0000 Sweet 8280.00 2120.0000

76.2000 787.5000

0.9800 Chlorinated, mothball 0.4900 Fishy, amine

Am. Ind. Hyg. Assoc. J. (47)

0

3i ~

TABLE I (cont.) .E

Odor High Description Chemical Compound

Musk oil Mustard gas Myrcene Naphthalene Nickel carbonyl Nitric acid Nitric oxide Nitrobenzene Nitroethane Nitrogen dioxide Nitromethane Nitropropane (1-) Nitropropane (2-) Nonane Nonanol (2-) Octadiene (1,3-) Octane Octyl alcohol Oxygen difluoride Ozone Parathion Pentaborane Pentachlorophenol Pentane Pentanedione (2,4-) Pentanol (n-) Perchloroethylene Perchloromethyl mercaptan Perchloryl fluoride Phenol Phenyl ether Phenyl ethyl alcohol (beta-) Phenyl sulfide Phenylacetaldehyde Phosgene Phosphine Phthalic Anhydride Picoline (2-) Picric aciel Propane Propionaldehyde Propionic acid Propyl acetate (n-) Propyl alcohol Propyl alcohol (n-) Propyl mercaptan Propyl nitrate (n-) Propyl sulfide Propylene Propylene diamine Propylene dichloride Propylene glycol dinitrate Propylene glycol isobutyl ether Propylene glycol methylether Propylene oxide Pyridine Pyrrolidine Quinone Rotenone Safrole Silicon tetrafluoride Skatole Stoddard solvent Styrene (inhibited) Styrene (uninhibited) Styrene oxide

. Ind. Hyg. Assoc. I (47) March, 1986

Odor Low mg/m3

3.8 x 10'6 0.0150 0.0723 1.5000 0.2100 0.7500 0.3600 0.0235

620.0000 2.0000

250.0000 ro80.0000

17.5000 3412.5000

0.0005 54.0000

725.0000 0.6916 0.2000 0.0010 0.4760 2.5000

6.6000 0.0409 0.7560

31.3560 0.0075

46.6666 0.1786 0.0070

35.0000 0.0026 0.0010 2.0000 0.0280

0.0532 0.0005

1800.0000 0.0225 0.0840 0.2100

75.0000 0.0750 0.0002

210.0000 0.0531

39.5600 0.0424 1.1667 1.2000

60.5000 360.0000

24.7500 0.0090

58.0000 0.4000 5.7960 1.4586 4.2500

4.0 x 10'7 5.2500 0.4300 0.2021 0.3093

Irritating Cone. mg/m3

75.00

155:00

230.00 310.00

20.00 500.00 360.00

1450.00

2.00

10.90

1340.00

182.40 21.00

8.00 10.67 30.00

13750.00

2801.40

121.00 3600.00 1125.00

90.00

2.00

42.50

2100.00 4300.00 430.00

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mg/m'J

0.0487 0.0150 0.0723

125.0000 21.0000

2.5000 1.2000 9.5000

620.0000 10.0000

250.0000 1080.0000 1029.0000 3412.5000

20.6150 90.0000

1208.3300 0.6916 1.0000 1.0200 0.4760 2.5000

3000.0000 0.0982 1.1160

469.0000 0.0075

46.6666 22.4200

0.7000 35.0000

0.0358 0.0196 4.0000 3.6000

0.1748 0.0005

36000.0000 0.4029

60.0000 105.0000 500.0000 150.0000

0.0746 210.0000

0.0531 116.2720

0.2030 606.6660

1.5600 60.5000

360.0000 500.0000

15.0000 187.3400

0.4000 5.7960 1.4586 4.2500

0.2680 157.5000 860.0000 860.0000

1.9640

of Odor

Mothball, tar-like Musty

Shoe polish, pungent Mild, fruity Sweetish, acrid Mild, fruity Mild, fruity

Gasoline-like

Foul Pleasant, clover-like Garlic-like Strong, pungent Pungent when hot Gasoline-like Sour, rancid Sweet, alcohol Chlorinated solvent

Sweet Medicinal, sweet Disag reeable

Musty hay, green corn Oniony, mustard, fish

Sweet

Sweet, ester Sour Sweet, ester

Sweet, alcohol

Ether-like

Aromatic Sharp, amine Sweet

Sweet, alcoholic Burnt, sickening

Acrid

Perfume Kerosene-like Solventy, rubbery Solventy, rubbery Sweet

ODOR THRESHOLDS AND IRRITATION LEVELS: A REJIIEW

TABLE I (cont.)

Chemical Compound

Sulfur dichloride Sulfur dioxide Sulfur monochloride Sulfuric acid Tetrachloroethane (1,1,2,2-) Tetrachloroe.thyelene TetraethylorthoSilicate Tetrahydrofuran Tetra/in Tetramethylenediamine Thiophene Thiophenol mercaptan Toluene

petroleum Toluene

from coke Toluene 2,4 diisocyanate

TO! Toxaphene Trichloro fluoromethane

Freon 11 Trichloro trifluoroethane

Freon 113 Trichlorobenzene (1,2,4-) Trichloroethylene

TCE Trichloropropane (1,2,3-) Tricycloketone Triethyl amine Trimethyl amine Trimethyl phosphite Trimethylenediamine Trinitro tert-butylxylene

musk oil Turpentine Valerie acid Vanillin Vinyl acetate Vinyl amyl ketone Vinyl butyl ketone Vinyl propyl ketone Vinyl pyridine Vinyl toluene Vinylidene chloride VM&P naphtha Xylene Xylidene

Odor low mg/m3

0.0042 1.1750

1.0000 21.0000 31.3560 30.6360

7.3750 97.2000 79.2000

0.0026 0.0012 8.0250

17.5500

3.2000

2.3660 28.0000

342.0000

24.0000 1.1340

1.8660 0.3600 0.0008 0.0005

3757.2000 3.8 x 10'6

560.0000 0.0026

2.0 x 10'7 0.3600 0.5150 0.0321 0.0201 1.1670

240.0000 2000.0000

3.8700 0.3480 0.0240

3 .!!1 .....od .c e>by- .~

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or recognize an9 describe the odor. Finally, some researchers look for a 100% panel resportse. This latter method would generate higher concentration levels as the defined thresh­old. One stutlY, which reported both the absolute thresh­old and the 100% recognition threshold, showed the 100% recognitionthresho~d to be approximately two to ten times higher than the absolute threshold.(24)

The influence of chemical contaminants may explain some of the variation in thresholds observed.(21) Note the differences in odor thresholds in Table I o(toluene manufac­tured from two different ra w materials, or carbon tetrachlo­ride from different sources, or inhibited vs. uninhibited sty­rene. There has been a tendency for lower thresholds to be identified in the more recent research, which has been attrib­

A·150

Odor High Description mg/m3 of Odor

0.0042 Sulfidy 12.5000 Yech!

Nauseating 1.0000

35.0000 Sickly sweet 469.0000 Chlorinated solvent

61.2720 Sweet, alcohol 177.0000 Ether-like 97.2000 79.2000

0.0026 Aromatic 382.5000 150.0000 Rubbery, mothballs

262.5000 Floral, pungent

17.1200 Sweet, fruity, acrid

2.3660 1170.4000 Sweet

1026.0000 Sweet

24.0000 2160.0000 Solventy

Strong, acrid 870.8000

1.1200 Fishy, amine 0.0008 Fishy, pungent 0.0005 Pyridine-like

11968.5000 0.0487

1120.0000 0.0026

Perfume 1.6500 Sour, sharp 0.5150 0.0321 0.0201 1.9450 Nauseating

240.0000 Disagreeable 4000.0000 Sweet, chloroformish

3.8700 174.0000 Sweet

0.0240 Weak, amine-like

Irritating Conc. mg/m~

5.00 12.00 1.10

1302.00 710.20

750.00

750.00

4.00

40.00 864.00

300.00

200.00

560.00

240.00

435.00

uted to greater purity of samples and better techniques 0

sample presentation,

Discussion

It must be remembered that the data listed in Table I an~'

essentially for the single chemical constituent with no othe~

chemicals present in the air. Mixtures of different chemical~'

have received very little study.(28) The question is whetheQ two chemicals at concentrations below their odor thresholds (RA and RB) can add up to constitute one combined "odor" (RAB) which is perceived, or whether the olfactory receptor~

react very specifically to each chemical so that no odor i{ perceived(17) (Figure I - Independence). There have been several studies where two mixed chemicals, each at 50% of its

Am. Ind. Hyg Assoc. J. (47)'

odor threshold, have produced an odor which was perceived Hygiene and Toxicology, Vol. IIC - Toxicology, 3rd rev. ed. 'by test subjects(17) (Figure I - Addition). While mixed chemi­ New York: John Wiley & Sons, 1982.

cals may betotally independent of one another or produce 11. Hille, V.E.: Bestehen BeZiehungen Zwishen den Geruchs­schwellenwerten undden Immissionsgrenzwerten Chemis­simple additive effects, it is also possible that the mixture cherSubstanzen? Staub Reinhalt. Luft 37(5):199-201. (1977).

produces an enhanced or a suppressed reaction from what 12. Braker, W., A.L. Mossman and D. Siegel: Effects of Expo­

might be predicted. An enhanced reaction would result from sure to Toxic Gases.- First Aid and Medical Treatment, 2nd

two mixed chemicals, each at less than 50% of its odor ed. Lyndhurst, N.J.: Matheson, 1977. pp. 7-151. threshold, which produce a perceived odor (Figure I - Syn­ 13. Manufacturing Chemists Association: Chemiclli Safety Data ergism). A suppressed reaction, or counteraction, would Sheets. Washington" DC. result when two mixed chemicals, each at 100% of its odor 14. Summer, W.: Odour Pollution of Air - Causes and Control. threshold, fail to produce a perceptible oeor among test London: Leonard Hill, 1971. pp. 22-24, 28, 43, 159.

subjects (Figure I - Counteraction). 15. National Research Council, Committee on Odors from Sta­tionary and Mobile Sources: Odors from Stationary andIndependence, Mobile Sources. Washington, D.C.: National Academy ofRAB = RA or RB Sciences, 1979. pp. 24-27, .182-183.

Addition 16. American Society for Testing and Materials, Committee RAE = RA + RB E-18 on Sensory Evaluation of Materials and Products:

Compilation of Odor and Taste Threshold Values Data. Synergism Edited by FA Fazzalari. Philadelphia: ASTM.

RAB >RA + RB 17. May, J.: Odor Thresholds of Solvents for Assessment of

Counteraction SOlvent Odors in the Air (UDC 614.718:66.062-911. RAE < RA or RB 3:613.155.3:612.867). Staub Reinhalt. Luft 26(9):34-38 (1966).

18. Cheremisinoff, P.N. and R.A. Young, eds.: Industrial Odor Technology Assessment. Table 8-11. Ann Arbor, Mich.:

where RAB = odor threshold of mixture of chemical A and chemical B,

Ann Arbor Science Publishers, 1975. RA = odor threshold of pure chemical A, and 19. Katz, S.H. and E.J. Talbert: Intensities of Odors and Irritat­RB = odor threshold of pure chemical B.

ing Effects of Warning Agents for Inflammable and Poison­Figure 1 - Mixed Chemicals Odor RelationshipsYSJ ous Gases. Bureau of Mines Technical Paper 480.

Washington, D.C.: U.S. Government Printing Office, 1930. References

20. Matsushitia, H., J. Arito, Y. Suzuki and R. Sod~: Determina­1. American Conference of Governmental Industrial Hygien­ tion of Threshold Values for Olfactory Percep'~ion of Prim­

ists,Committee on Industrial Hygiene: Industrial Ventila­ary Odour Substances. Ind. Health 5:221-237 (1967). tion - A Manual of Recommended Practice, 17th ed. Lans­ (National Institute of Industrial Health, Kawasaki, Japan). ing, Mich.: ACGIH, 1982. pp. 13-20. 21. Arthur D. Little, Inc.: Research on Chemical Odors, Part I ­

2. Billings, C.E. and L.C. Jonas: Odor Thresholds in Air as Odor Thresholds for 53 Commercial Chemicals. Washing­Compared to Threshold Limit Values. Am. Ind. Hyg. Assoc. ton, D.C.: Manufacturing Chemists Association, 1965. pp. EJ. 42:479-480 (1981). 1-26. .g

3. American Industrial Hygiene Association: Hygienic Guide 22. Trayer, D.M.: Odor Thresholds for Air Contaminants. Safety ',r~ Series, Vol. I. Akron, Ohio: AIHA. Newsletter - Public Utilities Section June 1976. Chicago, "0.

84. American Industrial Hygiene Association: Hygienic Guide III.: National Safety Council, 1976. p.2. Series, Vol. II. Akron, Ohio: AIHA. 23. Occupational Health Resource Center, Oregon Lung Asso­ ~

Q)5. National Institute for Occupational Safety and Health: ciation: Warning Properties of Industrial Chemicals. c roNIOSH/OSHA Occupational Health Guidelines for Chemi­Portland, Oreg. a

cal Hazards (DHHS/NIO$H Pub, No. 81-123). Washington, £rn

D.C.: Government Printing Office, 1981. Properties of 101 Petrochemicals Using Sensory Methods. 24. Hellman, T.M. and F.H. Small: Characterization of the Odor

c: o6. Alliance of American Insurers: Technical Guide No.6 ­J. Air Poll. Control Assoc. 24:979-982 (1974). roHandbook of Organic Industrial Solvents, 5th ed. Chicago, .;::25. American Conference of Governmental Industrial Hygie­

III.: AAI, 1980. pp. 55-107. nists: Threshold Limit Values® for Chemical Substances 7. Alliance of American Insurers: Technical Guide No. 7 ­ and Physical Agents in the Work Environment with Intended E

G.lHandbook of Hazardous Materials, 2nd ed. Schaumburg, Changes for 1984-85. Cincinnati, Ohio: ACGIH. 19'84. pp. .c: *III.: AAI, 1983. pp. 70-210. 9-33. r­

8. Clayton, G.D. and F.E. Clayton, eds.: Patty's Industrial 26. Brody, J.E.: What the Nose Knows. This World July 24, Hygiene and Toxicology•. Vo. IIA - Toxicology, 3rd rev. ed. 1983. pp. 13-14. New York: John Wiley and Sons, 1981. 27. Wilby, F.V.: Variation in Recognition Odor Threshold of a

9. Clayton, G.D. and F.E. Clayton, eds.: Patty's Industrial Panel. J. Air Poll. Control Assoc. 19:96-100 (1969). Hygiene and Toxicology, Vol. liB - Toxicology. 3rd rev. ed. 28. Rosen, A.A., J.B. Peter and F.M. Middleton: Odor Thre­New York: John Wiley & Sons, 1981. sholds of Mixed Organic Chemicals. Journal WPCF.

10. Clayton, G.D. and F.E. Clayton, eds.: Patty's Industrial 34(1 ):7-14 (1962).

Am. Ind. Hyg Assoc. J. (47) March, 1986 A·l5l