United States
                                   Environmental Protection
                                   Agency
                                  Health Effects Research
                                  Laboratory
                                  Research Triangle Park NC 2771 1
v°/EPA
                                   Research and Development
                                  EPA-600/S1-81-044  July 1981
Project  Summary
                                   Effects  of  Sulfuric  Acid
                                   Mist  Exposure  on
                                   Pulmonary  Function

                                   Steven M. Horvath, Lawrence J  Folmsbee, and John F. Bedi
                                    The effects of sulfuric acid particle
                                   concentration (mass/volume), particle
                                   size, and ambient temperatures on
                                   pulmonary  function of young male
                                   nonsmokers were examined. Subjects
                                   repeated three times a sequence of 20-
                                   minute exercise (ventilation of approxi-
                                   mately 30 l/min) and 20-minute sitting
                                   rest. Pre- and post-exposure pulmonary
                                   functions (forced vital capacity ma-
                                   neuvers, lung  volumes, maximum
                                   voluntary ventilation,  Raw TQV and
                                   helium-oxygen  FVC) were measured.
                                   During the  exposure and at the 5th
                                   minute after cessation of each exercise
                                   period, forced vital capacity tests (air
                                   and helium-oxygen) were performed.
                                   Each subject was exposed in random
                                   order to filtered  air or 233, 418 or 939
                                   jug/m3 particulate sulfuric acid. Particle
                                   sizes were MMD, 0.91 -0.93 fjm. geo-
                                   metric SD,  1.66-1.73. Two subject
                                   groups were studied in two different
                                   ambient conditions, i.e. approximately
                                   22°C dry bulb, 55% relative humidity,
                                   and 35°C dry bulb, 85% relative hu-
                                   midity. Sulfuric acid concentrations
                                   were slightly higher during the hot
                                   environmental exposures. No signifi-
                                   cant changes in pulmonary functions
                                   related to sulfate were observed in
                                   subjects intermittently exercising in
                                   the cool environment. Metabolic mea-
                                   surements during exercise indicated a
                                   trend towards increased ventilation
                                   and oxygen  uptake with duration of
                                   exposure. The only significant  differ-
                                   ence which was related to sulfate
                                  exposure was a higher respiratory rate
                                  compared to filtered air. Heart rates
                                  were similar under all conditions. In
                                  the hot humid environment, forced
                                  vital capacity decreased with time of
                                  exposure but was not related to pol-
                                  lutant exposure. The only significant
                                  interaction for pollutants across time
                                  was seen for FEF75%, where the post-
                                  exposure values were greater than the
                                  pre-exposure values under filtered air
                                  conditions  but not during sulfate
                                  exposure. This observation was not
                                  corroborated by changes in FEF75-
                                  85%, which increased post-exposure
                                  under all conditions. Three subjects
                                  were studied during exposure to 14OO
                                  fjg/m3. No changes were observed.
                                  Predictable increases in heart rate,
                                  rectal temperature, ventilation and
                                  oxygen uptake were found but were
                                  not related to sulfate exposure, being
                                  simply the  influence of the altered
                                  ambient conditions. Exposure to sul-
                                  furic acid mist in the 1 fjm particle size
                                  range and in concentrations up to
                                  1200 yug/m3 had  relatively minor
                                  effects on the cardiopulmonary system.
                                   This report was submitted in ful-
                                  fillment of Grant No. R804853 by the
                                  Institute of  Environmental  Stress,
                                  University of California, Santa Barbara,
                                  under the sponsorship of the U.S.
                                  Environmental Protection Agency.
                                  This report covers a period from April
                                  1, 1977 to August 31, 1980, and
                                  work was completed as of August 31,
                                  1980.

-------
   This Project Summary was developed
 by EPA's Health Effects Research
 Laboratory. Research Triangle Park.
 NC, to announce key findings of the
 research project that is  fully docu-
 mented in a separate report of the
 same title fsee Project Report ordering
 information at back).


 Introduction
  The increasing use of coal and petro-
 leum products with high sulfur content
 has raised concern about the potential
 health effects of  sulfur-containing air
 pollutants. Early studies  found that
 humans exposed briefly (10-16 min) to
 sulfuric acid concentrations of 0.35 to 5
 mg/m3 and 4 to 40 mg/m3 (particle size
 1 fjm) respectively, exhibited increased
 coughing, altered respiratory patterns
 and bronchoconstriction. However,
 more recent studies again exposed
 subjects  briefly to 10, 100, and 1000
 /jg/m3 to either  sodium  chloride or
 sulf uric acid aerosols (0.1  to 0.2 fjm).
 These 10-minute exposures of either
 normal or asthmatic individuals did not
 induce any alterations in  pulmonary
 functions. The  effects on  pulmonary
 functions of intermittently exercising
 subjects breathing sulfuric acid (75
jug/m3, particle size 0.48-0.81 /urn) were
 investigated. No convincing adverse
 short-term health effects were observed.
 Ten subjects inhaled via nasal mask 0.5
/urn H2SO4 at 0,  100, 300 and 1000
fjg/m3 for one hour. Although  no sig-
 nificant changes in respiratory dynamics
 were observed, bronchial mucociliary
 clearance was altered. Respiratory
 effects of sulfuric acid aerosol in normal
 subjects exposed for four hours to 100
A/g/m3 H2SO4 of particle size 0.1 to 0.3
(jrr\ were evaluated. The subjects per-
 formed two 15-minute bouts of exercise
 during the exposure period. No signifi-
 cant differences in pulmonary function
 were observed during or after the expo-
 sure. The conflicting results reported
 could have been related to the size of the
 aerosol particles utilized in the different
 experimental situations.
  We  examined the effects of sulfuric
 acid particle concentration (mass/vol-
 ume)  at  an ambient temperature of
 22°C  and 55% relative humidity on
 pulmonary function  of young male
 nonsmokers. All exposures were con-
 ducted in an environmental chamber.
 Eleven subjects thrice repeated a se-
 quence of 20-minute exercise (ventila-
tion approximately 30 liters/min) and
 20-minute sitting rest during the 2-hour
exposure. Pre- and post-exposure
pulmonary function tests (forced vital
capacity maneuvers, lung volumes,
maximum voluntary ventilation, Raw,
TGV, and helium-oxygen FVC) were
measured. During the exposure and at 2
minutes after cessation of each exercise
period, forced vital capacity tests (air
and  helium-oxygen) were performed.
Each subject was exposed in random
order to filtered air or 233, 418, or 939
jug/m3 particulate sulfuric acid. Mass
median diameter (MMD) was 0.90-0.93
/jm, and geometric SD was 1.66-1.73.

Results
  No major changes in pulmonaryfunc-
tion related to sulfate were observed in
these subjects (Tables 1 and 2). The only
measurement to show a significant
interaction across time (pre - post) and
sulfate concentration was FEVt o, which
was  significantly decreased with expo-
sure to 939 fjg/m3 sulfate. The  magni-
tude of the decrease was not considered
to be of physiological significance.
These results indicate that, even with
the added stress of the increased depth
and  volume of ventilation associated
with exercise, exposure to as much as 1
mg/m3 of 1 /ym sulfuric acid aerosol for
2 hours has little if any effect on standard
tests of lung function. Many subjects
noticed a dry or metallic taste in the air.
At the highest concentration, throat
irritation or dryne'ss and  cough were
frequently noted. Eye irritation was
reported by two subjects at 939 //g/m3
of sulfate. Several individuals reported
dizziness, fatigue, or headache, which
were usually associated with exercise
and  had no relationship with sulfate
levels in the ambient air.

Discussion
  These data indicate that there was no
significant effect of sulfuric acid aerosol
in the 1 -micron (0.9 fjm) size range and
in concentrations between 200 and
1000//g/m3 on the pulmonary function
of young male nonsmokers. The results
of the present study support previous
studies of human exposure to sulfuric
acid  aerosols in the 0.3 to 0.5 fjm size
range at similar concentrations (100-
1000 fjg/m3). However, they do not con-
firm  studies in which subjects were
exposed to larger aerosols. Subjects in
the study described herein were not
only exposed for longer periods; the
quantity of inhaled aerosol was inten-
tionally increased by having the subjects
exercise so that their ventilatory volumes
were intermittently increased up to 30
liters/ min. The increased prevalence of
symptoms such as cough, dry throat, or
throat irritation suggests that the sulfu-
ric acid may have caused some irritation
to the tracheal mucosa although not to a
sufficient degree to induce functional
changes. These symptoms were usually
noted only when the subject took a deep
or rapid inspiration and generally only at
the beginning of the exposure period.

Conclusions
  It is apparent that additional investi-
gations involving long-term exposures
(rest and exercise combinations), small
and large particles, and various ambient
humidities need to be conducted. Some
attention must also be given to the mode
of administration. Chamber studies
which  more closely simulate natural
environments are  preferred,  but the
interrelationship between such expo-
sures  and those utilizing oral or a
combination of oral-nasal inhalation
require clarification.

-------
able 1 . Pulmonary Function
Exposures; Mean ±

Forced vital Pre
capacity (L) Post"
f£Vi o (U Pre
Post"
FEV3o(L) Pre
Posta
Inspiratory Pre
capacity (L) Post"
Expiratory Pre
res. vol. (L) Post
Funct. res. Pre
capacity (L) Post
FEF25-75% Pre
'L/s) Post
Max. volunt. Pre
vent. (L/min) Post
Airway res. Pre
'Us/cm HZ0) Post
FEF50% Pre
'L/s) Post
FEF75% Pre
'L/s) Post
FEF75-85% Pre
'L/s) Post
Measurements in Subjects Exposed to Various Concentrations of H2SOt (Pre & Post 2-Hour
SDJ
0 ug/m3
5.64 (±0.58)
5.58 (±0.56)
4.47 (±0.46)
4.7 9 (±0.48)
5. 58 (±0.59 )
5.55 (±0.57)
3.62 (±0.48)
3.48 (±0.45)
2.02 (±0.45)
2. JO (±0.45)
3.66 (±0.74)
3.73 (±0.72)
4.97 (±0.69)
5.06 (±0.81)
202 (±34)
205 (±33)
1.67 (±0.39)
J. 76 (±0.58)
5.57 (±0.77)
5. 63 (±1.03)
2.80 (±0.65)
2.93 (±0.80)
2. 12 (±0.59)
2. 22 (±1.02)
223 ug/m3
5. 65 (±0.55)
5. 54 (±0.63)
4. 83 (±0.54)
4.80 (±0.57)
5.61 (±0.57)
5.51 (±0.64)
3. 58 (±0.49)
3.49 (±0.58)
2. 02 (±0.36 )
2.05 (±0.38)
3. 68 (±0.73)
3.76 (±0.70)
5. 14 (±0.89)
5.36 (±1.11)
206 (±35)
202 (±41)
1.7 3 (±0.35)
1.77 (±0.57)
5.85 (±1.01)
6. 12 (±0.98)
2. 83 (±0.57)
3.05 (±0.90)
2. 20 (±0.54)
2. 32 (±0.7 2)
418 ug/m3
5.66 (±0.61)
5. 59 (±0.63)
4. 72 (±0.55)
4.76 (±0.55)
5.61 (±0.62)
5. 54 (±0.63)
3.61 (±0.55)
3. 49 (±0.46)
2.05 (±0.47)
2. 12 (±0.45)
3.72 (±0.69)
3. 80 (±0.7 6)
4.97 (±0.74)
5. 05 (±0.80)
199 (±35)
204 (±39)
1.75 (±0.52)
1.64 (±0.46)
5.97 (±0.85)
5. 84 (±0.96)
2. 83 (±0.68)
2. 88 (±0.77)
2.29 (±0.61)
2. 32 (±0.70)
939 ug/m3
5. 65 (±0.61)
5.47 (±0.60)
4. 82 (±0.57)
4.72 (±0.57)
5. 62 (±0.63)
5.44 (±0.57)
3. 54 (±0.50)
3.40 (±0.46)
2. 12 (±0.39)
2. 06 (±0.40)
3. 74 (±0. 74)
3.76 (±0.73)
5. 1 1 (±0.88)
5. 29 (±1.08 )
211 (±35)
209 (±32)
1.87 (±0.48)
1.69 (±0.41)
5.82 (±0.97)
5.81 (±1.15)
2.76 (±0.61)
2.89 (±0.7 3)
2. 13 (±0.68)
2.28 (±0.71)
"Post < Pre overall - no difference across sulfate concentrations.
Vre (FA, 418)< Pre (223, 939); Pre (939) > Post (939).
able 2. Pulmonary Function

Forced vital Pre
capacity (L) 25
65
105
FEVi o (L) Pre
25
65
JOS
FEV3.0 (L) Pre
25
65
105
Inspiratory Pre
capacity (L) 25
65
105
FEF25-75% Pre
(L/s) 25
65
JOS
Measurements During 2-Hour
0 ug/m3
5. 35 (±0.54)
5.21 (±0.6 1)
5. 24 (±0.62)
5. 16 (±0.62)
4. 65 (±0.49)
4. 48 (±0.54)
4.53(±O.58)
4.52 (±0.52)
5. 33 (±0.56)
5. 18 (±0.6 1)
5. 23 (±0.63)
5. 13 (±0.61)
3. 48 (±0.48)
3. 25 (±0.59)
3. 29 (±0.43)
3. 19 (±0.42)
4. 9 2 (±0.79)
4.7 3 (±0.83)
4.90 (±1.01)
5.05 (±0.83)
Exposure to HiSO*
223 ug/m3
5. 25 (±0.55)
5. 25 (±0.56)
5.21 (±0.56)
5.23 (±0.57)
4.53 (±0.51 )
4. 43 (±0.64)
4. 45 (±0.53)
4. 56 (±0.64)
5. 22 (±0.56)
5. 19 (±0.60)
5. 17 (±0.59)
5.20 (±0.54)
3.39 (±0.57)
3.23 (±0.58)
3. 32 (±0.55)
3. 36 f ±0.60)
4.91 (±0.83)
4.82 (±1.21)
5.1 3 (±1.05)
5.10 (±1.30)
(Mean ± SO)
418 ug/m3
5. 30 (±0.54)
5. 20 (±0.58)
5. 24 (±0.56)
5. 17 (±0.53)
4.51 (±0.57)
4.43 (±0.59)
4. 52 (±0.49)
4.53 (±0.53)
5. 28 (±0.55)
5. 12 (±0.59)
5. 19 (±0.56)
5. 14 (±0.54)
3.43 (±0.43)
3. 34 (±0.49)
3.31 (±0.49)
3.26 (±0.45)
4.75 (±0.97)
4.64 (±0.97)
4.81 (±0.89)
4.90 (±0.89)

939 ug/m3
5.28 (±0.59)
5. 20 (±0.59)
5. 17 (±0.61)
5. 13 (±0.62)
4.55 (±0.57)
4. 49 (±0.55)
4. 44 (±0.55)
4. 48 (±0.57)
5. 26 (±0.59)
5. 16 (±0.59)
5. 15 (±0.62)
5.10 (±0.20)
3. 43 (±0.54)
3. 29 (±0.46)
3.21 (±0.49)
3. 22 (±0.48)
4. 90 (±0.83)
4. 90 (±0.84)
4.84 (±0.95)
5.02 (±0.80)
* US GOVERNMENT PRINTING OFFICE 1901 -757-012/7226

-------
    Table 2.    (continued)
                                          0 fjg/m3
                           223
418 tig/m3
939
FEF50%
(L/s)
FEF75%
(L/s)
Pre
25
65
105
Pre
25
65
105
4. 80 (±0.83)
4.73 (±0.81)
4.88 (±0.98)
5. 05 (±0.80)
2.53 (±0.61)
2.51 (±0.71)
2. 53 (±0.84)
2. 65 (±0.73)
4. 99 (±0.78)
4.76 (±1.1 4)
4. 98 (±0.84)
5. 03 (±1.08)
2. 66 (±0.70)
2. 50 (±0.65)
2. 64 (±0.77)
2.66 (±0.87)
4. 69 (±0.99 )
4. 54 (±0.94)
4. 76 (±0.91)
4. 8 3 (±0.93)
2. 40 (±0.74)
2. 49 (±0.84)
2. 47 (±0.72)
2.63 (±0.78)
4. 92 (±0.85)
5. 00 (±O.86)
4. 92 (±0.89)
5. 00 (±0.9 2)
2. 54 (±0.58)
2. 56 (±0.57)
2. 52 (±0.68)
2. 59 (±0.66)
                                             Steven  M. Horvath, Lawrence J.  Folinsbee,  and John F. Bedi are with the
                                               Institute of Environmental Stress. University of California, Santa Barbara, CA
                                               93106.
                                             Donald H. Horstman is the EPA Project Officer (see below).
                                             The complete report, entitled "Effects of Suit uric A cid Mist Exposure on Pulmon-
                                               ary Function."(Order No. PB 81 -208 977; Cost: $9.50, subject to change) will
                                               be available only from:
                                                     National Technical Information Service
                                                     5285 Port Royal Road
                                                     Springfield, VA 22161
                                                     Telephone: 703-487-4650
                                             The EPA Project Officer can be contacted at:
                                                     Health Effects Research Laboratory
                                                     U.S. Environmental Protection Agency
                                                     Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
                Postage and
                Fees Paid
                Environmental
                Protection
                Agency
                EPA 335
Official Business
Penalty for Private Use $300
        PS    0000 4? 9
        u  s  tiW
-------