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Benzene exposure in a Japanese petroleum refinery
135
Toxicology Letters, 52 (1990) 135139 Elsevier TOXLET 02347
Benzene exposure in a Japanese petroleum refinery*
Toshio Kawail, Kazutoshi Yamaokal, and Masayuki Ikeda2 ‘Osaka Occupational
Yoko Uchida2
Health Service Center. Osaka and 2Deparment of Public Health. Kyoto University
Faculty of Medicine, Kyoto (Japan)
(Received 22 September 1989) (Accepted 18 February 1990) Key words: Benzene; Breathing zone air analysis; Diffusive sampling; Petroleum refinery
SUMMARY Time-weighted average (TWA) intensity of exposure of workers to benzene vapor during a shift was monitored by diffusive sampling technique in a Japanese petroleum refinery. The subjects monitored (83 in total) included refinery operators, laboratory personnel and tanker-loading workers. The results showed that the time-weighted average exposures are well below 1 ppm in most cases. The highest exposure was recorded in 1 case involved in bulk loading of tanker ships, in which exposure of over 1 ppm might take place depending on operational conditions. The observation was generally in agreement with levels previously reported.
INTRODUCTION
It is known that benzene (an established human carcinogen [l]) is present, even though at low percentages, in commercial fuel gasoline [2] and also in low-boilingpoint petroleum distillates [3]. This observation has raised concerns about possible exposure of workers to benzene among other insidiously hazardous materials at petroleum refineries [4] where benzene is industrially produced. Accordingly several reports have been published from the United States [>8] and some Western European
*Part of this work was presented at the 62nd Annual Meeting of Japan Association of Industrial Health, held in Hirosaki, Japan, on 27-31 April, 1989.
Addressfor correspondence: Prof. M. Ikeda, Department of Public Health, Kyoto University Faculty of Medicine, Kyoto 606, Japan. 0378-4274/90/$3.50 @ 1990 Elsevier Science Publishers B.V. (Biomedical Division)
136
countries [9,10] on benzene exposure in refineries, but no report has so far appeared on Japanese refineries. The present study was initiated to help address this issue utilizing diffusive samplers for monitoring the average exposure of workers during different operations in a Japanese refinery. MATERIALS AND METHODS
Workers and method of exposure monitoring The workers monitored were a group of operators in a petroleum refinery in Japan, and included 1 specific worker who loaded liquid benzene onto a chemical tanker (Table I). Stationary sampling was also conducted in the vicinity of the benzene-loading operation, as a supplemental study for exposure assessment. Diffusive sampling was conducted utilizing carbon cloth KF-1500 (Toyobo Co., Osaka, Japan) as absorbent. Each worker studied had a diffusive sampler on the lapel for the time period of operation indicated. After exposure was terminated, the benzene absorbed on the carbon cloth was extracted with carbon disulfide (spiked with sec.-butylbenzene as internal standard) and analyzed with a FID gas chromatograph as previously described [ 1 l-l 31. The lowest measurable benzene concentration after 8 h of exposure was 0.01 ppm. Statistical analysis For presentation of vapor concentrations, tions were assumed.
both normal and log-normal distribu-
RESULTS AND DISCUSSION
Table I summarizes the results of measurements. Refining and pipeline workers were monitored for more than 8 h since they served on a 2-shifts-per-day basis (i.e., 12 h a day, 2 working days in 3 days), whereas exposure of other workers was examined for 8 h or less. The time-weighted average (TWA) intensity of exposure was well below 1 ppm (upper half of Table I). The geometric mean for each group was in the range of 0.074.71 ppm, and the maximum exposure recorded was also below 1 ppm, except for 3 auxiliary workers, who were exposed to 1.10, 1.97 and 2.67 ppm (as TWA), respectively. Perusal of their work records revealed that they were engaged in the loading of benzene onto and unloading of petroleum from tanker ships. Accordingly, the benzene-loading operation was studied in more detail. One delivery worker was engaged in connecting and disconnecting a loading hose with a joint on the deck of a benzene tanker. Since measurement of exposure of seamen on board the ship was not possible, stationary sampling at 10 crosses of a hypothetical grid (35 m in distance between 2 grid lines) on the deck of the tanker was conducted as a surrogate. The expo-
137
TABLE
I
BENZENE
EXPOSURE
OF REFINERY
Job category
No.~
WORKERS
Time(min)b MkSD
Benzene concentrationC M&SD
GM (GSD)
Min.-Max.
Factory workers
Refining
worker@
Pipeline workers’ Delivery
674+
79
0.07 * 0.04
0.05 (2.30)
N.D.a.15
666k
70
0.10+0.08
0.07 (2.35)
N.D.a.28
workers’
Laboratory
personnel
Auxiliary
8
489k
61
0.19*0.09
0.15 (2.35)
0.03 a.29
20
464+
33
0.08+0.11
0.05 (2.61)
N.D.q.51
13
389f
96
0.71 kO.75
0.42 (3.07)
0.04 -2.67
82
557* 134
0.19+0.38
0.09 (3.26)
N.D.-2.67
1
250
0.1
10
205i
0.05 (4.36)
N.D.a.46
workersr
Total Ship loading
Delivery
qf benzene
worker
Stationary Unless
9 32
samplingh
otherwise
specified,
the values
21
0.11*0.14
in the table were obtained
by personal
sampling
with diffusive
samplers. =Number bDuration
of workers
examined.
of diffusive sampling.
% ppm, except GSD which is dimensionless. as if it were 0.01 ppm. dEngaged
in distillation
“Engaged
in product
fin charge
of petroleum
and reforming
transfer
For calculation
N.D. ( CO.01 ppm) is taken
processes.
by pipelines.
unloading
and product
delivery by ship.
xServing as helpers
in various
processes.
They were engaged
in loading
of benzene onto and unloading
%t the vicinity of the loading
of GM (GSD),
Three cases had exposure
above
of petroleum
1 ppm (1.10, 1.97, 2.67 ppm). from a tanker
ship.
hose and on the deck of a benzene tanker.
sure of the delivery worker was less than 1 ppm, and none of the stationary sampling results exceeded 1 ppm (lower half of Table I). Thus, the high exposure could not be reproduced. It was considered probable that the reduced exposure might be due to the careful positioning of the worker on the windward side of the delivery joint, and possibly to the weather conditions (e.g., velocity and direction of wind) since this was outdoor work. Another site of product delivery was a rack for gasoline tank trucks. Product-loading was performed by truck drivers themselves, the work being monitored by operators who sit in a room at a distance and supervise a computerized controlling system. Thus, exposure of the controlling operators was considered minimal. The exposure of truck drivers is described elsewhere [14]. In brief, their exposure to benzene was well below 1 ppm on a daily basis with a very short-term peak exposure of up to 20 ppm at the time of loading.
138
The present observation that benzene exposure in a petroleum refinery is generally low and that exposure in association with delivery by ship might be somewhat higher than others is in agreement with previous publications [5,6,&10,15]. In a review of benzene exposure in the United States in 1978-1983, Runion and Scott [6] summarized that the geometric mean benzene concentration in refining was estimated at 0.05 ppm, whereas the estimate of exposure for loading of benzene onto ships/barges was 1.3 ppm. Similarly, Spear et al. [8] found in the statistical analysis of the 1978-1984 measurements that most 8-h TWA exposures in 9 refining companies were below 1 ppm, and that the jobs involving benzene loading and unloading operations of barges or tanker trucks were often associated with higher exposures. In an epidemiology study on benzene-exposed workers in a large refinery, Tsai et al. [5] stated that 84% of the 1394 measurements by personal sampling were less than 1 ppm and that the median for the refinery workers was 0.14 ppm. According to a report from Sweden [9], TWA benzene exposure of Swedish refinery workers in the early 1980s was in the range of 0.1-1.0 mg/m3 (about 0.03-0.3 ppm), but TWA exposure at levels higher than 6 mg benzene/m3 (about 2 ppm) would take place in 21% (in winter) and 42% (in summer) of tanker-loading operations [ 161. Higher exposure of coast tanker crews to benzene (6.6 ppm mean, 23 ppm maximum) was also reported [lo]. It appears reasonable, therefore, to conclude that there has been a gradual decrease in benzene exposure in petroleum refineries, and that present-day exposure levels in modern refineries will be well below 1 ppm in general with possibly higher exposure associated with loading and unloading of benzene. Efforts are currently being made in the refinery studied to reduce further the exposure to benzene.
REFERENCES 1 International
Agency
for Research
on Cancer
(1987) Benzene. IARC
Monogr.
Eval. Carcinog.
Risks
Hum., Suppl. 7, 12&122. 2 Ikeda, M., Kumai, gasoline
in Japan.
3 Kasahara, aromatic
M., Watanabe, Ind. Health
M., Suzuki, components
4 International and gasoline.
Agency
T. and Fujita, H. (1984) Aromatic
H., Takeuchi, in petroleum for Research
IARC Monogr.
Y., Hara, distillate
on Cancer
Eval. Carcinog.
I. and Ikeda,
and medical
surveillance
M. (1987) n-Hexane,
solvents in Japan.
Ind. Health
(1989) Occupational Risks Hum. 45,39-l
5 Tsai, S.P., Wen, C.P., Weiss, N.S., Wong, O., McClellan, mortality
and other contents
in automobile
22,235-241.
studies of workers
benzene and other
25,205-214.
exposures
in petroleum
refining,
17, 159-201.
W.A. and Gibson, in benzene
R.L. (1983) Retrospective
areas of refineries.
J. Occup.
Med.
25,685692. 6 Runion,
H.E. and Scott, L.M. (1985) Benzene exposure
Am. J. Ind. Med. 7,385-393. 7 Rappaport, S.M., Selvin, S. and Waters, line in the petroleum
industry,
M.A. (1987) Exposure
States 1978-1983:
to hydrocarbon
an overview.
components
of gaso-
Appl. Ind. Hyg. 2, 148-154.
8 Spear, R.C., Selvin, S., Schulman, ing industry.
in the United
J. and Francis,
M. (1987) Benzene exposure
in the petroleum
refin-
Appl. Ind. Hyg. 2, 155-163.
9 Holmberg, B. and Lundberg, Med. 7.3755383.
P. (1985) Benzene:
standards,
occurrence,
and exposure,
Am. J. Ind.
139 10 Berlin, M. (1988) Biological monitoring of populations exposed to volatile petroleum products. Ann. NY Acad. Sci. 534,472480. 11 Hirayama, T. and Ikeda, M. (1979) Applicability of carbon felt to the dosimetry of solvent vapor mixture. Am. Ind. Hyg. Assoc. J. 40, 1091-1096. 12 Ikeda, M., Kumai, M. and Aksoy, M. (1984) Application of carbon felt dosimetry to field studies distant from analytical laboratory. Ind. Health 22,5358. 13 Kasahara, M. and Ikeda, M. (1987) Spontaneous desorption of organic solvents from carbon cloth. Ind. Health 2573-81. 14 Kawai, T., Yamaoka, K., Uchida, Y. and Ikeda, M. (1990) Exposure to vapors of benzene and other aromatic solvents in tanker truck loading and delivery (submitted for publication). 15 Nordlinder, R. and Ram&, 0. (1983) Cited by Holmberg and Lundberg [9]. 16 Gjiirloff, K., Skldin, B. and Svedung, I. (1982) Cited by Holmberg and Lundberg [9].
Toxicology Letters, 52 (1990) 135139 Elsevier TOXLET 02347
Benzene exposure in a Japanese petroleum refinery*
Toshio Kawail, Kazutoshi Yamaokal, and Masayuki Ikeda2 ‘Osaka Occupational
Yoko Uchida2
Health Service Center. Osaka and 2Deparment of Public Health. Kyoto University
Faculty of Medicine, Kyoto (Japan)
(Received 22 September 1989) (Accepted 18 February 1990) Key words: Benzene; Breathing zone air analysis; Diffusive sampling; Petroleum refinery
SUMMARY Time-weighted average (TWA) intensity of exposure of workers to benzene vapor during a shift was monitored by diffusive sampling technique in a Japanese petroleum refinery. The subjects monitored (83 in total) included refinery operators, laboratory personnel and tanker-loading workers. The results showed that the time-weighted average exposures are well below 1 ppm in most cases. The highest exposure was recorded in 1 case involved in bulk loading of tanker ships, in which exposure of over 1 ppm might take place depending on operational conditions. The observation was generally in agreement with levels previously reported.
INTRODUCTION
It is known that benzene (an established human carcinogen [l]) is present, even though at low percentages, in commercial fuel gasoline [2] and also in low-boilingpoint petroleum distillates [3]. This observation has raised concerns about possible exposure of workers to benzene among other insidiously hazardous materials at petroleum refineries [4] where benzene is industrially produced. Accordingly several reports have been published from the United States [>8] and some Western European
*Part of this work was presented at the 62nd Annual Meeting of Japan Association of Industrial Health, held in Hirosaki, Japan, on 27-31 April, 1989.
Addressfor correspondence: Prof. M. Ikeda, Department of Public Health, Kyoto University Faculty of Medicine, Kyoto 606, Japan. 0378-4274/90/$3.50 @ 1990 Elsevier Science Publishers B.V. (Biomedical Division)
136
countries [9,10] on benzene exposure in refineries, but no report has so far appeared on Japanese refineries. The present study was initiated to help address this issue utilizing diffusive samplers for monitoring the average exposure of workers during different operations in a Japanese refinery. MATERIALS AND METHODS
Workers and method of exposure monitoring The workers monitored were a group of operators in a petroleum refinery in Japan, and included 1 specific worker who loaded liquid benzene onto a chemical tanker (Table I). Stationary sampling was also conducted in the vicinity of the benzene-loading operation, as a supplemental study for exposure assessment. Diffusive sampling was conducted utilizing carbon cloth KF-1500 (Toyobo Co., Osaka, Japan) as absorbent. Each worker studied had a diffusive sampler on the lapel for the time period of operation indicated. After exposure was terminated, the benzene absorbed on the carbon cloth was extracted with carbon disulfide (spiked with sec.-butylbenzene as internal standard) and analyzed with a FID gas chromatograph as previously described [ 1 l-l 31. The lowest measurable benzene concentration after 8 h of exposure was 0.01 ppm. Statistical analysis For presentation of vapor concentrations, tions were assumed.
both normal and log-normal distribu-
RESULTS AND DISCUSSION
Table I summarizes the results of measurements. Refining and pipeline workers were monitored for more than 8 h since they served on a 2-shifts-per-day basis (i.e., 12 h a day, 2 working days in 3 days), whereas exposure of other workers was examined for 8 h or less. The time-weighted average (TWA) intensity of exposure was well below 1 ppm (upper half of Table I). The geometric mean for each group was in the range of 0.074.71 ppm, and the maximum exposure recorded was also below 1 ppm, except for 3 auxiliary workers, who were exposed to 1.10, 1.97 and 2.67 ppm (as TWA), respectively. Perusal of their work records revealed that they were engaged in the loading of benzene onto and unloading of petroleum from tanker ships. Accordingly, the benzene-loading operation was studied in more detail. One delivery worker was engaged in connecting and disconnecting a loading hose with a joint on the deck of a benzene tanker. Since measurement of exposure of seamen on board the ship was not possible, stationary sampling at 10 crosses of a hypothetical grid (35 m in distance between 2 grid lines) on the deck of the tanker was conducted as a surrogate. The expo-
137
TABLE
I
BENZENE
EXPOSURE
OF REFINERY
Job category
No.~
WORKERS
Time(min)b MkSD
Benzene concentrationC M&SD
GM (GSD)
Min.-Max.
Factory workers
Refining
worker@
Pipeline workers’ Delivery
674+
79
0.07 * 0.04
0.05 (2.30)
N.D.a.15
666k
70
0.10+0.08
0.07 (2.35)
N.D.a.28
workers’
Laboratory
personnel
Auxiliary
8
489k
61
0.19*0.09
0.15 (2.35)
0.03 a.29
20
464+
33
0.08+0.11
0.05 (2.61)
N.D.q.51
13
389f
96
0.71 kO.75
0.42 (3.07)
0.04 -2.67
82
557* 134
0.19+0.38
0.09 (3.26)
N.D.-2.67
1
250
0.1
10
205i
0.05 (4.36)
N.D.a.46
workersr
Total Ship loading
Delivery
qf benzene
worker
Stationary Unless
9 32
samplingh
otherwise
specified,
the values
21
0.11*0.14
in the table were obtained
by personal
sampling
with diffusive
samplers. =Number bDuration
of workers
examined.
of diffusive sampling.
% ppm, except GSD which is dimensionless. as if it were 0.01 ppm. dEngaged
in distillation
“Engaged
in product
fin charge
of petroleum
and reforming
transfer
For calculation
N.D. ( CO.01 ppm) is taken
processes.
by pipelines.
unloading
and product
delivery by ship.
xServing as helpers
in various
processes.
They were engaged
in loading
of benzene onto and unloading
%t the vicinity of the loading
of GM (GSD),
Three cases had exposure
above
of petroleum
1 ppm (1.10, 1.97, 2.67 ppm). from a tanker
ship.
hose and on the deck of a benzene tanker.
sure of the delivery worker was less than 1 ppm, and none of the stationary sampling results exceeded 1 ppm (lower half of Table I). Thus, the high exposure could not be reproduced. It was considered probable that the reduced exposure might be due to the careful positioning of the worker on the windward side of the delivery joint, and possibly to the weather conditions (e.g., velocity and direction of wind) since this was outdoor work. Another site of product delivery was a rack for gasoline tank trucks. Product-loading was performed by truck drivers themselves, the work being monitored by operators who sit in a room at a distance and supervise a computerized controlling system. Thus, exposure of the controlling operators was considered minimal. The exposure of truck drivers is described elsewhere [14]. In brief, their exposure to benzene was well below 1 ppm on a daily basis with a very short-term peak exposure of up to 20 ppm at the time of loading.
138
The present observation that benzene exposure in a petroleum refinery is generally low and that exposure in association with delivery by ship might be somewhat higher than others is in agreement with previous publications [5,6,&10,15]. In a review of benzene exposure in the United States in 1978-1983, Runion and Scott [6] summarized that the geometric mean benzene concentration in refining was estimated at 0.05 ppm, whereas the estimate of exposure for loading of benzene onto ships/barges was 1.3 ppm. Similarly, Spear et al. [8] found in the statistical analysis of the 1978-1984 measurements that most 8-h TWA exposures in 9 refining companies were below 1 ppm, and that the jobs involving benzene loading and unloading operations of barges or tanker trucks were often associated with higher exposures. In an epidemiology study on benzene-exposed workers in a large refinery, Tsai et al. [5] stated that 84% of the 1394 measurements by personal sampling were less than 1 ppm and that the median for the refinery workers was 0.14 ppm. According to a report from Sweden [9], TWA benzene exposure of Swedish refinery workers in the early 1980s was in the range of 0.1-1.0 mg/m3 (about 0.03-0.3 ppm), but TWA exposure at levels higher than 6 mg benzene/m3 (about 2 ppm) would take place in 21% (in winter) and 42% (in summer) of tanker-loading operations [ 161. Higher exposure of coast tanker crews to benzene (6.6 ppm mean, 23 ppm maximum) was also reported [lo]. It appears reasonable, therefore, to conclude that there has been a gradual decrease in benzene exposure in petroleum refineries, and that present-day exposure levels in modern refineries will be well below 1 ppm in general with possibly higher exposure associated with loading and unloading of benzene. Efforts are currently being made in the refinery studied to reduce further the exposure to benzene.
REFERENCES 1 International
Agency
for Research
on Cancer
(1987) Benzene. IARC
Monogr.
Eval. Carcinog.
Risks
Hum., Suppl. 7, 12&122. 2 Ikeda, M., Kumai, gasoline
in Japan.
3 Kasahara, aromatic
M., Watanabe, Ind. Health
M., Suzuki, components
4 International and gasoline.
Agency
T. and Fujita, H. (1984) Aromatic
H., Takeuchi, in petroleum for Research
IARC Monogr.
Y., Hara, distillate
on Cancer
Eval. Carcinog.
I. and Ikeda,
and medical
surveillance
M. (1987) n-Hexane,
solvents in Japan.
Ind. Health
(1989) Occupational Risks Hum. 45,39-l
5 Tsai, S.P., Wen, C.P., Weiss, N.S., Wong, O., McClellan, mortality
and other contents
in automobile
22,235-241.
studies of workers
benzene and other
25,205-214.
exposures
in petroleum
refining,
17, 159-201.
W.A. and Gibson, in benzene
R.L. (1983) Retrospective
areas of refineries.
J. Occup.
Med.
25,685692. 6 Runion,
H.E. and Scott, L.M. (1985) Benzene exposure
Am. J. Ind. Med. 7,385-393. 7 Rappaport, S.M., Selvin, S. and Waters, line in the petroleum
industry,
M.A. (1987) Exposure
States 1978-1983:
to hydrocarbon
an overview.
components
of gaso-
Appl. Ind. Hyg. 2, 148-154.
8 Spear, R.C., Selvin, S., Schulman, ing industry.
in the United
J. and Francis,
M. (1987) Benzene exposure
in the petroleum
refin-
Appl. Ind. Hyg. 2, 155-163.
9 Holmberg, B. and Lundberg, Med. 7.3755383.
P. (1985) Benzene:
standards,
occurrence,
and exposure,
Am. J. Ind.
139 10 Berlin, M. (1988) Biological monitoring of populations exposed to volatile petroleum products. Ann. NY Acad. Sci. 534,472480. 11 Hirayama, T. and Ikeda, M. (1979) Applicability of carbon felt to the dosimetry of solvent vapor mixture. Am. Ind. Hyg. Assoc. J. 40, 1091-1096. 12 Ikeda, M., Kumai, M. and Aksoy, M. (1984) Application of carbon felt dosimetry to field studies distant from analytical laboratory. Ind. Health 22,5358. 13 Kasahara, M. and Ikeda, M. (1987) Spontaneous desorption of organic solvents from carbon cloth. Ind. Health 2573-81. 14 Kawai, T., Yamaoka, K., Uchida, Y. and Ikeda, M. (1990) Exposure to vapors of benzene and other aromatic solvents in tanker truck loading and delivery (submitted for publication). 15 Nordlinder, R. and Ram&, 0. (1983) Cited by Holmberg and Lundberg [9]. 16 Gjiirloff, K., Skldin, B. and Svedung, I. (1982) Cited by Holmberg and Lundberg [9].