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Ambient and biological monitoring of exposure to polycyclic aromatic hydrocarbons at a coking plant
ELSEVIER
The Science of the Total Environment 199 (1997) 151-158
Ambient and biological monitoring of exposure to polycyclic aromatic hydrocarbons at a coking plant L. Pyya,*, M. MZkelS”, E. Hakala”, K. Kakko”, T. Lapinlampi”, A. Liskob, E. Yrjbheikki”, K. VZh%kangasd ‘Oulu
Regional Institute of Occupational Health, Aapistie 1, FIN-90220 Oulu, Finland bRautamukki Oy Raahe Steel Works, PO Box 93, FIN-92101 Raahe, Finland cMinistry of Labour, Division of Occupational Safety and Health, PO Box 536, FIN-33101 Tampere, Finland ‘Deparmtent of Pharmacology and Toxicology, University of Oulu, FIN-90220 Oulu, Finland
Abstract The exposureto polycyclic aromatic hydrocarbons(PAH) was measuredin a Finnish coking plant over a 7-year period (1988-19941,sincethe beginningof production. Hygienic measurements including dust and vapour sampling were performed and the correlations between the concentrationsof airborne pyrene with the levels of pyrene metabolite 1-pyrenol in urine were calculated. The profile of measured12 or 15 PAHs was very similar between mean concentrationsof personalsamples,which suggeststhat it is possibleto calculate the concentration of total PAH by usinge.g. pyrene asa marker compound.Measurementssuggestthat the progressof working conditionshas been very favourable becausethe meanexposurelevel of shift workers to benzo[a]pyrene has decreasedfrom 2.5 pg/m3 to 0.3 pg/m3. This points to successfulmeasuresof technical prevention. The mean concentration of 1-pyrenol in urine hasbeen 0.2-0.6 pmol/mol creatinine. The concentration increasesslightly towardsthe end of the working day, but the correlation betweenurinary pyrenol and air pyrene wasweak. Therefore the usefulnessof pyrenol level for predicting the pyrene concentration at low exposure level in the ambient air is very limited. 0 1997Elsevier ScienceB.V. Keywords:
Polycyclic aromatic hydrocarbons; Urinary 1-pyrenol; Urinary 1-naphthol; Coke oven; Occupational
exposure
1. Introduction Coke used in the sintering and blast furnace processesis produced by heating coal in a coking
* Corresponding author. Tel.: + 358 8 5376001; fax: + 358 8 5376115; e-mail: [email protected] 0048-9697/97/$17.00 PII
SOO48-9697(97)00065-X
oven with an oxygen-free environment (pyrolysis). The ovens are charged on top of the battery of parallel ovens with a larry car. The coke is transferred from the ovens by opening the oven doors mechanically and pushing the coke out to a transportation wagon on the other side of the battery, which transfers the coke to the quenching unit. When the charging lids and oven doors
0 1997 Elsevier Science B.V. All rights reserved.
157
L. &y et al. /The Science of the Total Environment I99 (1997) 151-158
are opened or are leaking, diffuse smoke and dust emissions are released into the working air. The working environment in coking plants is particularly problematic as the gas from the pyrolysis of coal contains among other compounds, ammonia, hydrogen sulphide, phenols and hydrocarbons, such as polycyclic aromatic hydrocarbons (PAH). Some estimations about PAH emissions of different processes have been made. The emissions of benzo[a]pyrene (BaP) in Germany have been assumed to be reduced to 60 mg/ton coke and the newest plant shows emissions of 40 mg BaP/ ton coke (Eisenhut et al., 1990). Estimates of annual emissions in 1985 of total PAH in the steel production of Norway are 34 t/year (Bjorseth and Ramdahl, 1985). The occupational exposure has been classified according to the measured BaP concentrations as follows (Lindstedt and Sollenberg, 1982): .
very high BaP exposure (10 pg/m3), coke work (topside work); l fairly high BaP exposure (l-10 pg/m3) coke works in general (non-topside work), blast furnaces, steel works (some jobs); a moderate BaP exposure (0.1-l pg/m3>, steel works (in general), foundries (some jobs); l low BaP exposure (0.01-0.1 pg/m3), foundries (in general).
It has been observed that the relative content of PAH (PAH profile) is relatively constant in the same industry (Jongeneelen, 1992; Ny et al., 1993). Therefore the measurement of one of the major PAH compounds can be used to predict the exposure to total PAH. Pyrene is one of the major PAH compounds in the air of coking plants and its major metabolite l-pyrenol has been successfully applied to measure the total internal PAH dose. One problem in the biological monitoring of pyrene is the question of half-lives. Considerable variation in the half-life of 1-pyrenol has been found, with values between 6 and 35 h reported (Jongeneelen et al., 1990; Buchet et al., 1992). A general recommendation is to analyse 1-pyrenol in after-shift samples at the end of the working period. There are also recommendations for biological reference values for urinary l-
pyrenol from coke oven workers. These values are in the range of 1-5 pmoljmol creatinine (Levin. 1995). Considerable attention has been paid to PAH compounds as they increase cancer risk. In addition to coke production, the International Agency for Research on Cancer W&C) has classified aluminium production as a cause of cancer in humans (IARC, 19851. The IARC has reported that there is evidence for 11 PAH compounds being carcinogenic to experimental animals (IARC, 1983). PAHs are known to be absorbed through the skin and it is important to keep in mind that the dermal absorption of PAH compounds often represents the main part of their total dosage WanRooij et al., 1993). This means that careful protection of the skin is required at the workplaces as an important preventive measure. Although PAH compounds occur in the work environment as complicated mixtures containing tens, even hundreds, of compounds, in practice only a few are routinely analysed (Hein et al., 1994). For this reason only known compounds such as BaP or the 16 most important PAH compounds classified by the EPA are analysed (USEPA, 1982; NIOSH, 1985). The purpose of this study was to find out the emission points and identify and quantify emitted compounds as well as measure the exposure of individual workers. The aim was to follow up systematically the PAH exposure and produce reliable data for technical improvements, to develop personal protection and define the needs of occupational health care. Furthermore, the objective was to prove and develop methods, both hygienic and biological, for the assessment of PAH exposure. The design and first results of biomonitoring, which was the part of the total research project have been published earlier Wahakangas et al., 1992). 2. Material
and methods
2.1. Study design
The study was carried out at the coking plant of Rautaruukki, Raahe Steel, which started to func-
L. &y et al. / The Science of the Total Environment
tion as the first and only Finnish coking plant in 1987. The annual production was doubled in 1992 to the level of one million tons and is in balance with the coke consumption of the Works’ blast furnace. The number of staff at the start of the coking plant was about 170 and the increase of production brought with it 20 new vacancies. During the study many technical improvements have been completed. The design and the parameters of the study are presented in Table 1. The total study included seven phases. The preliminary phase was carried out before the coking plant was taken into operation and it involved the collection of biological samples. 2.2. Air sampling and analyses
Each sampling phase of hygienic measurements was completed during 7 days, the first phase being in May 1988, half a year after the start of the coking plant. Measurements in May were repeated in 1989, 1990, 1992, 1993 and 1994. In 1988-1990 particulate PAH compounds were collected on filters as personal and stationary sampling and gaseous compounds in XAD tubes only as stationary sampling. All personal samples were taken outside the protective respirator if it was in
199 (1997)
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U-158
use. From dust samples taken in 1988-1992 the concentrations of 12 PAHs were determined by high performance liquid chromatography (Yrjanheikki et al., 1995). In the spring of 1992 the air sampling was expanded to include personal sampling for gaseous PAHs. Also the new analytical method for the determination of 15 PAH compounds according to the NIOSH recommendations were adopted (MakeG and Pyy, 1995). Of the PAH compounds included in the old method used in 1998-1992 two substances, benzo[ alfluorene and benzo[e]pyrene were not included in the new method. The new method completed the PAH selection with the five following PAHs: acenaphthene, fluoranthene, benz[a]anthracene, benzo[ blfluoranthene and indeno[l,2,3-cdlpyrene. Samples collected in 1992 were analyzed using both the new and old HPLC methods. The correlation coefficient between the methods was 0.89 for pyrene, the new method giving 1.67 times higher results than the older one. For BaP the correlation coefficient was 0.95 and the results by the new method were, on an average, 77% of those by the old method. The new HPLC method is based on multiple wavelength shift fluorescence detection of PAH. As a consequence interference
Table 1 The design of the study and the number of biological and air samples Phase Biological samples Blood Urine Dust (PAH) Stationary Personal
1987 (A)
1988 03
1989 (C)
1990 CD)
1992 (E)
1993 03
1994 (G)
150 155
150 155
150 147
130 132
160 197
50 105
160 323
-
152 57 95
190 56 134
168 51 111
194 60 134
131 50 51
275 88 127
30
30 -
141 66 75
116 81 35
172 86 86
-
47 39 8
49 49
95
Vapour (PAHI Stationary Personal Vapour (VOC) Stationary Personal
-
-
-
30
56 39
If;4
L. f)y
et al. /The
Science of the Total Environment
from the sample matrix decreases, which makes the interpretation of the results more reliable. The detection limits of lo-100 rig/m’ were achieved for different PAH-compounds depending on air volumes used for sampling. The within-series variation was determined by analysing the real sample 10 times. The relative standard deviation (RSD) for different PAH compounds was l.O-3.5% and for pyrene 2.0%. Accuracy was demonstrated by analysing the NIST standard reference material 1647 in different series. The results for pyrene were 95-100% of the target value. 2.3. Urine sampling and analyses
Spot urine samples were collected from workers in 1987-1990 before the working shift. In 1987 samples were collected before the cooking plant started to function. Biological sampling was planned to perform on the same days as air sampling on the second day of the morning shift. From practical reasons this was not always possible. At the most unfavourable situation in 1990 about one-fifth of samples had to be taken on the first day of the shift period. As a control, in 1989-1990 samples were collected from a reference group (40 persons) without occupational exposure working in the offices of the steel works. In 1992 the samples were collected at the end of the shift. From some workers several samples were collected during the day for assessment of kinetic factors. Some workers gave urine samples at the beginning and end of the working hours, in the evening and during the next morning. In 1993-1994 the samples were collected before and at the end of the shift. Samples were divided into 5-ml aliquots and stored at -20°C. Urine samples were analysed for 1-pyrenol by a HPLC method with fluorescence detection (Jongeneelen et al., 1987). The detection limit (twice the signal-to-noise ratio) of 1-pyrenol was 0.1 nmol/l and the precision (RSD) of the method was 3.0% obtained in 10 replicate analyses of a sample with a concentration of 10 nmol/l. The RSD 3.0% is the within-series variation. The variation of the results throughout the phases were followed by analysing a pooled urine sample at a
I99 (19971151-158
concentration level of 2.6 nmol/l of l-pyrenol. On the average, the RSD within a phase was 5.0% (N = 6, between-day variation) and between the phases 14% (N = 12, between-year variation). Specific gravity and creatinine were determined and used to standardise the results. 2.4. Statistical evaluation
Basic statistics of data were performed with the SPSS for Windows 6.1. software. Correlations of urinary 1-pyrenol with the pyrene concentrations in air were calculated using SAS procedures for personal computers. Pearson correlation coefficients (r) and linear regression equations were calculated, which are expressed in the form of y = ax + b, where x is the concentration of pyrene in air ( pg/m31 and y the urinary 1-pyrenol concentration ( ~mol/mol creatinine). 3. Results 3.1. Occupational
hygienic measurements
The mean concentration of BaP in personal samples of shift workers varied between 0.3 and 2.5 pg/m3 (Fig. 1). Pyrene concentration was at the same range, 0.5-3.5 pg/m3. In 1993-1994 the BaP exposure was on the level of 0.3 pg/m3. The new method was used for measurements in 1993 and, because it gives higher concentrations for pyrene, the decrease in exposure for pyrene is more distinct than Fig. 1 suggests. In 1992-1994 all the results were lower than the present Finnish occupational BaP exposure limit of 10 pg/m3. Most of the results were below 1 pg/m3 and e.g. in 1994 the maximum concentration (2.2 pg/m3> was found in the sample of a gas worker, who has the highest exposure among all the top side workers. However the average concentration of gas workers was below 1 pg/m3. In stationary samples the highest BaP concentration (5 ,ug/m3) was found on the bridge of the larry car. The PAH profile in all study phases was very consistent (Fig. l), e.g. in phase G there exists a good linear correlation (coefficient 0.990) between pyrene and the total PAH (the sum of 15 PAH compounds), hence it should be possible to use
L. Pp et al. /The Science of the Total Environment 199 (1997) 151-158
the pyrene as a marker compound and predict the concentrations of other PAHs by calculation. Napthalene was the main compound in the XAD samples and its concentration was at the level of 100 pg/m3. 3.2. Urinary metabolites of PAHs
The kinetics of urinary excretion of 1-pyrenol was studied in 1992 (phase E) from the samples of 10 workers, who gave urine samples before a shift, after the shift, in the evening and during the next morning. Also, the concentrations of pyrene in the breathing zone of workers were measured (range 0.09-2.6 pg/m3, mean 1.10 pg/m3). The concentration of 1-pyrenol was always higher af-
155
ter the shift than before the shift. The workers were divided according to the concentration of pyrene in air, into the moderate exposure group (< 1.0 pg/m3, mean 0.41 pg pyrene/m3, n = 6) and to the fairly high exposure group (> 1.0 pg/m3, mean 2.12 pg pyrene/m3, n = 4). The mean concentrations of 1-pyrenol in urine in the moderate exposure group were 0.09 pmol/mol creatinine before the shift, 0.30 after the shift, 0.20 in the evening and 0.14 in the next morning (Fig. 2). The concentrations in the fairly high exposure group were 0.34, 0.69, 0.46, and 0.09 ~mol/mol creatinine, respectively. Table 2 summarizes all the urinary 1-pyrenol results and in Table 3 the results of 1993-1994 are divided in pro- and post-shift results. Large
PAH Wm”>
DUST (mg/m”)
1988
(N-,0)
lPhass
C, 1989
,N=68)
lPhars
D. 1090
(N=48)
OPhrsa
E, ,992
(N-67)
l Phase
F. 7993
(N-20)
rnPh.lSO
G, ,994
(NI66)
PAH compound Fig. 1. Average concentrations of identified PAH compounds and dust in personal samples of shift workers during different study periods. Abbreviations: NPH, Naphthalene; CHR, Chrysene; FL, Fluorene; BeP, Benzo[elpyrene; PHE, Phenanthrene; BkFLU, Benzo[klfluoranthene; ANT, Anthracene; BaP, Benzo[a]pyrene; PYR, Pyrene; diBahA, Dibenzo[a,h)anthracene; BaFL, Benzo [alfluorene; BghiP, Benzo[ghilperylene.
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1L. &y et al. /The
Science of the Total Environment
199 (1997)
ISI-1%
1 = before shift
2 = after shift 3 = evening 4 = nex morning Fig. 2. Mean urinary excretion of l-pyrenol before a shift (11, after the shift (2), in the evening (3) and in the next morning (4) in the moderate exposure group 1 (< 1 pg pyrene/m3; n = 6) and fairly high exposure group 2 (> 1 Kg pyrene/m3; n = 4).
differences between arithmetic means and medians suggest 1-pyrenol concentrations distribute log-normally rather than normally. Before the start of the plant the mean concentration of urinary I-pyrenol was 0.3 pmol/mol creatinine (Table 2). The mean level of 1-pyrenol increased slightly during the first 2 years of production to 0.6 and 0.4 pmol/mol creatinine, and since 1990 Table 2 Urinary l-pyrenol ( pmol/mol Statistics Sampling Mean Median Max Min N Notes:
it was at the level of 0.2 pmol/mol creatinine. In F and G phases (1993-1994) the urinary l-pyrenol level increased slightly during working days, but the difference was not correlated with pyrene concentration in the air. It seems that significant correlation between urinary pyrenol and air pyrene appeared only in the first phase B (1998), when the exposure was at it’s highest. The corre-
creatinine) of coke workers and referents during study phases, all results
1987 (A>
1988 03
1989 (0
1989
1990
(ReD
CD)
1990 (ReD
1992 (E)
1993 (F)
1994 (G)
Pre 0.29 0.18 2.68 0.02 155
Pre 0.62 0.40 5.05 0.00 1.56
Pre 0.44 0.27 3.04 0.05 142
Pre 0.11 0.06 0.88 0.01 40
Pre 0.17 0.12 1.13 0.02 130
Pre 0.14 0.06 1.13 0.01 38
Post 0.17 0.07 1.53 0.01 172
Pre + 0.21 0.13 1.42 0.01 104
Post 0.14 0.08 2.35 0.01 323
Pre, pro-shift sampling; Post, post-shift sampling.
L. Pyy et al. /The Science of the Total Environment 199 (1997) 151-158 Table 3 Urinary 1-pyrenol ( ymol/mol creatinine) of coke workers in pre-shift and post-shift samples during study phases F and G Statistics
1993 (F)
1993 (F)
1994 (G)
1994 (G)
Sampling Mean Median Max Min N
Pre 0.16 0.08 1.29 0.01 54
Post 0.26 0.16 1.42 0.01 52
Pre 0.12 0.08 1.99 0.01 165
Post 0.16 0.10 2.35 0.01 159
lation equation was y = 0.15x + 0.67 and the correlation coefficient Y was 0.59 (P = 0.0001, N = 43). Urinary 1-naphthol concentrations determined for a small number of samples (N = 24) showed that no correlation between urinary and air concentrations can be found and 1-naphthol seems to be an uncertain marker for an assessment of air concentration of naphthalene. The mean of creatinine corrected l-naphthol values was 0.032 ~mol/mol creatinine (range 0.000-0.205, N = 20). For the before work samples the mean concentration was low (mean 0.011, range 0.000-0.038, N = 10) and the concentration increased significantly towards the after work samples (mean 0.056, range 0.000-0.205, N = 10).
157
of occupational exposure limits (OEL) in several countries - in Finland the OEL value is 10 @m”. A comprehensive measurement programme has given reliable information of exposure and so the effect of technical improvements can be easily followed. The results reported to the staff of the coking plant have promoted technical protection. Furthermore, the information of the study has motivated the employers to correct the use of personal protection and to make working habits safer. Acknowledgements The authors express their gratitude to the Finnish Work Environmental Fund for its financial support. The authors wish to thank the staff and management of Rautaruukki Steel coking plant for excellent collaboration, and especially Dr. J. Kaisko and Mr. E. Muuruvirta for organising the collection of biological samples. Warm thanks are also due to the laboratory personnel of Oulu Regional Institute of Occupational Health and Department of Pharmacology and Toxicology, University of Oulu. References
4. Discussion Although the exposure levels already during the starting year were lower than at many older coking plants several technical improvements have further decreased the exposure. The mean exposure of the shift workers in 1993 was one-tenth of that in 1988. According to the ranking of Lindstedt and Sollenberg (1982) even the topside work at this coking plant belongs to a class ‘moderate BaP exposure’. The concentrations of 1-pyrenol (Tables 1 and 2) indicate very low exposure if compared to biological exposure limits 2.3 pmol/mol creatinine (Jongeneelen, 1992) or l-5 pmol/mol creatinine (Levin, 1995), proposed for coke oven workers. These biological exposure limits have been found to correspond to a BaP concentration of 2-5 pg/m3, which is the range
Bjorseth, A. and Ramdahl, T. (19851 Handbook of Polycyclic Aromatic Hydrocarbons. Marcel Dekker, New York, pp. 1-416. Buchet, J.P., Gennart, J.P., Mercado-Calderon, F., Delavignette, J.P., Cupers, L. and Lauwerys, R. (19921 Evaluation of exposure to polycyclic aromatic hydrocarbons in a coke production and a graphite electrode manufacturing plant: assessment of urinary excretion of l-hydroxypyrene as a biological indicator of exposure. Br. J. Ind. Med. 49, 761. Eisenhut, W., Friedrich, F. and Reinke, M. (1990) Coking plant environment in West-Germany. Coke Making Int. 1, 74-77. Hein, M., Friedricdh, F. and Eisenhut, W. (1994) Polycyclic aromatic hydrocarbons in the environment of coke oven plants. Coke Making 6(l), 40-43. International Agency for Research on Cancer (IARC) (1983) Polynuclear aromatic compounds. Part 1. Chemical, environmental and experimental data. In: IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Humans, Vol. 32. Lyon.
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Science of the Total Environment
International Agency for Research on Cancer (IARC) (19851 Polynuclear aromatic compounds. Part 4. Bitumens, coal tars and derived products, shale oils and soots. In: IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Humans, Vol. 35. Lyon. Jongeneelen, F.J. (1992) Biological exposure limit for occupational exposure to coal tar pitch volatiles at cokeovens. Int. Arch. Occup. Environ. Health 63, 511-516. Jongeneelen, F.J., Anzion, R.B.M. and Henderson, P.Th (1987) Determination of hydroxyiated metabolites of polycyclic aromatic hydrocarbons in urine. J. Chromatogr. 413, 227-232. Jongeneelen, F.J., van Leeuwen, F.E., Oosterink, S., Anzion, R.B.M., van der Loop, F. and Bos, R.P. (1990) Ambient and biological monitoring of cokeoven workers: determinants of the internal dose of polycyclic aromatic hydrocarbons. Br. J. Ind. Med. 47,454-461. Levin, J.O. (1995) First international workshop on hydroxypyrene as a biomarker for PAH exposure in man summary and conclusions. Sci. Total Environ. 163, 165-168. Lindstedt, G. and Sollenberg, J. (1982) Polycyclic aromatic hydrocarbons in the occupational environment. Stand. J. Work Environ. Health 8, 1-19. Makell, M. and Pyy, L. (1995) Effect of temperature on retention time reproducibility and on the use of pro-
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grammable fluorescence detection of fifteen polycyclic aromatic hydrocarbons. J. Chromatogr. A 699, 49-57. The National Institute of Occupational Safety and Health (NIOSH) (19851 NIOSH Manual of Analytical Methods NIOSH 5506-l. Cincinnati, Ohio. Ny, E.T., Heederik, D., Kromhout, H. and Jongeneelen, F. (1993) The relation between polycyclic aromatic hydrocarbons in air and in urine of workers in a Sijderberg potroom. Am. Ind. Hyg. Assoc. J. 54,277-284. United States Environmental Protection Agency (USEPA) (1982) Determination of Polycyclic Hydrocarbons in Municipal and Industrial Discharges; Method 610. Environmental Monitoring Systems Laboratory. Office of Research and Development, Cincinnati, OH. VanRooij, J.G.M., Bodelier-Bade, M.M. and Jongeneelen, F.J. (19931 Estimation of the individual dermal and respiratory uptake of polycyclic aromatic hydrocarbons of 12 coke oven workers. Br. J. Ind. Med. 50, 623-632. Vahlkangas, K., Pyy, L. and Yrjanheikki, E. (1992) Assessment of PAH-exposure among coke oven workers. Pharmacogenetics 2, 304-308. Yrjlnheikki, E., Pyy, L., Hakala, E., Lapinlampi, T., Lisko, A. and Vahakangas, K. (1995) Exposure to polycyclic aromatic hydrocarbons in a new coking plant. Am. Ind. Hyg. Assoc. J. 56,782-787.
The Science of the Total Environment 199 (1997) 151-158
Ambient and biological monitoring of exposure to polycyclic aromatic hydrocarbons at a coking plant L. Pyya,*, M. MZkelS”, E. Hakala”, K. Kakko”, T. Lapinlampi”, A. Liskob, E. Yrjbheikki”, K. VZh%kangasd ‘Oulu
Regional Institute of Occupational Health, Aapistie 1, FIN-90220 Oulu, Finland bRautamukki Oy Raahe Steel Works, PO Box 93, FIN-92101 Raahe, Finland cMinistry of Labour, Division of Occupational Safety and Health, PO Box 536, FIN-33101 Tampere, Finland ‘Deparmtent of Pharmacology and Toxicology, University of Oulu, FIN-90220 Oulu, Finland
Abstract The exposureto polycyclic aromatic hydrocarbons(PAH) was measuredin a Finnish coking plant over a 7-year period (1988-19941,sincethe beginningof production. Hygienic measurements including dust and vapour sampling were performed and the correlations between the concentrationsof airborne pyrene with the levels of pyrene metabolite 1-pyrenol in urine were calculated. The profile of measured12 or 15 PAHs was very similar between mean concentrationsof personalsamples,which suggeststhat it is possibleto calculate the concentration of total PAH by usinge.g. pyrene asa marker compound.Measurementssuggestthat the progressof working conditionshas been very favourable becausethe meanexposurelevel of shift workers to benzo[a]pyrene has decreasedfrom 2.5 pg/m3 to 0.3 pg/m3. This points to successfulmeasuresof technical prevention. The mean concentration of 1-pyrenol in urine hasbeen 0.2-0.6 pmol/mol creatinine. The concentration increasesslightly towardsthe end of the working day, but the correlation betweenurinary pyrenol and air pyrene wasweak. Therefore the usefulnessof pyrenol level for predicting the pyrene concentration at low exposure level in the ambient air is very limited. 0 1997Elsevier ScienceB.V. Keywords:
Polycyclic aromatic hydrocarbons; Urinary 1-pyrenol; Urinary 1-naphthol; Coke oven; Occupational
exposure
1. Introduction Coke used in the sintering and blast furnace processesis produced by heating coal in a coking
* Corresponding author. Tel.: + 358 8 5376001; fax: + 358 8 5376115; e-mail: [email protected] 0048-9697/97/$17.00 PII
SOO48-9697(97)00065-X
oven with an oxygen-free environment (pyrolysis). The ovens are charged on top of the battery of parallel ovens with a larry car. The coke is transferred from the ovens by opening the oven doors mechanically and pushing the coke out to a transportation wagon on the other side of the battery, which transfers the coke to the quenching unit. When the charging lids and oven doors
0 1997 Elsevier Science B.V. All rights reserved.
157
L. &y et al. /The Science of the Total Environment I99 (1997) 151-158
are opened or are leaking, diffuse smoke and dust emissions are released into the working air. The working environment in coking plants is particularly problematic as the gas from the pyrolysis of coal contains among other compounds, ammonia, hydrogen sulphide, phenols and hydrocarbons, such as polycyclic aromatic hydrocarbons (PAH). Some estimations about PAH emissions of different processes have been made. The emissions of benzo[a]pyrene (BaP) in Germany have been assumed to be reduced to 60 mg/ton coke and the newest plant shows emissions of 40 mg BaP/ ton coke (Eisenhut et al., 1990). Estimates of annual emissions in 1985 of total PAH in the steel production of Norway are 34 t/year (Bjorseth and Ramdahl, 1985). The occupational exposure has been classified according to the measured BaP concentrations as follows (Lindstedt and Sollenberg, 1982): .
very high BaP exposure (10 pg/m3), coke work (topside work); l fairly high BaP exposure (l-10 pg/m3) coke works in general (non-topside work), blast furnaces, steel works (some jobs); a moderate BaP exposure (0.1-l pg/m3>, steel works (in general), foundries (some jobs); l low BaP exposure (0.01-0.1 pg/m3), foundries (in general).
It has been observed that the relative content of PAH (PAH profile) is relatively constant in the same industry (Jongeneelen, 1992; Ny et al., 1993). Therefore the measurement of one of the major PAH compounds can be used to predict the exposure to total PAH. Pyrene is one of the major PAH compounds in the air of coking plants and its major metabolite l-pyrenol has been successfully applied to measure the total internal PAH dose. One problem in the biological monitoring of pyrene is the question of half-lives. Considerable variation in the half-life of 1-pyrenol has been found, with values between 6 and 35 h reported (Jongeneelen et al., 1990; Buchet et al., 1992). A general recommendation is to analyse 1-pyrenol in after-shift samples at the end of the working period. There are also recommendations for biological reference values for urinary l-
pyrenol from coke oven workers. These values are in the range of 1-5 pmoljmol creatinine (Levin. 1995). Considerable attention has been paid to PAH compounds as they increase cancer risk. In addition to coke production, the International Agency for Research on Cancer W&C) has classified aluminium production as a cause of cancer in humans (IARC, 19851. The IARC has reported that there is evidence for 11 PAH compounds being carcinogenic to experimental animals (IARC, 1983). PAHs are known to be absorbed through the skin and it is important to keep in mind that the dermal absorption of PAH compounds often represents the main part of their total dosage WanRooij et al., 1993). This means that careful protection of the skin is required at the workplaces as an important preventive measure. Although PAH compounds occur in the work environment as complicated mixtures containing tens, even hundreds, of compounds, in practice only a few are routinely analysed (Hein et al., 1994). For this reason only known compounds such as BaP or the 16 most important PAH compounds classified by the EPA are analysed (USEPA, 1982; NIOSH, 1985). The purpose of this study was to find out the emission points and identify and quantify emitted compounds as well as measure the exposure of individual workers. The aim was to follow up systematically the PAH exposure and produce reliable data for technical improvements, to develop personal protection and define the needs of occupational health care. Furthermore, the objective was to prove and develop methods, both hygienic and biological, for the assessment of PAH exposure. The design and first results of biomonitoring, which was the part of the total research project have been published earlier Wahakangas et al., 1992). 2. Material
and methods
2.1. Study design
The study was carried out at the coking plant of Rautaruukki, Raahe Steel, which started to func-
L. &y et al. / The Science of the Total Environment
tion as the first and only Finnish coking plant in 1987. The annual production was doubled in 1992 to the level of one million tons and is in balance with the coke consumption of the Works’ blast furnace. The number of staff at the start of the coking plant was about 170 and the increase of production brought with it 20 new vacancies. During the study many technical improvements have been completed. The design and the parameters of the study are presented in Table 1. The total study included seven phases. The preliminary phase was carried out before the coking plant was taken into operation and it involved the collection of biological samples. 2.2. Air sampling and analyses
Each sampling phase of hygienic measurements was completed during 7 days, the first phase being in May 1988, half a year after the start of the coking plant. Measurements in May were repeated in 1989, 1990, 1992, 1993 and 1994. In 1988-1990 particulate PAH compounds were collected on filters as personal and stationary sampling and gaseous compounds in XAD tubes only as stationary sampling. All personal samples were taken outside the protective respirator if it was in
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use. From dust samples taken in 1988-1992 the concentrations of 12 PAHs were determined by high performance liquid chromatography (Yrjanheikki et al., 1995). In the spring of 1992 the air sampling was expanded to include personal sampling for gaseous PAHs. Also the new analytical method for the determination of 15 PAH compounds according to the NIOSH recommendations were adopted (MakeG and Pyy, 1995). Of the PAH compounds included in the old method used in 1998-1992 two substances, benzo[ alfluorene and benzo[e]pyrene were not included in the new method. The new method completed the PAH selection with the five following PAHs: acenaphthene, fluoranthene, benz[a]anthracene, benzo[ blfluoranthene and indeno[l,2,3-cdlpyrene. Samples collected in 1992 were analyzed using both the new and old HPLC methods. The correlation coefficient between the methods was 0.89 for pyrene, the new method giving 1.67 times higher results than the older one. For BaP the correlation coefficient was 0.95 and the results by the new method were, on an average, 77% of those by the old method. The new HPLC method is based on multiple wavelength shift fluorescence detection of PAH. As a consequence interference
Table 1 The design of the study and the number of biological and air samples Phase Biological samples Blood Urine Dust (PAH) Stationary Personal
1987 (A)
1988 03
1989 (C)
1990 CD)
1992 (E)
1993 03
1994 (G)
150 155
150 155
150 147
130 132
160 197
50 105
160 323
-
152 57 95
190 56 134
168 51 111
194 60 134
131 50 51
275 88 127
30
30 -
141 66 75
116 81 35
172 86 86
-
47 39 8
49 49
95
Vapour (PAHI Stationary Personal Vapour (VOC) Stationary Personal
-
-
-
30
56 39
If;4
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et al. /The
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from the sample matrix decreases, which makes the interpretation of the results more reliable. The detection limits of lo-100 rig/m’ were achieved for different PAH-compounds depending on air volumes used for sampling. The within-series variation was determined by analysing the real sample 10 times. The relative standard deviation (RSD) for different PAH compounds was l.O-3.5% and for pyrene 2.0%. Accuracy was demonstrated by analysing the NIST standard reference material 1647 in different series. The results for pyrene were 95-100% of the target value. 2.3. Urine sampling and analyses
Spot urine samples were collected from workers in 1987-1990 before the working shift. In 1987 samples were collected before the cooking plant started to function. Biological sampling was planned to perform on the same days as air sampling on the second day of the morning shift. From practical reasons this was not always possible. At the most unfavourable situation in 1990 about one-fifth of samples had to be taken on the first day of the shift period. As a control, in 1989-1990 samples were collected from a reference group (40 persons) without occupational exposure working in the offices of the steel works. In 1992 the samples were collected at the end of the shift. From some workers several samples were collected during the day for assessment of kinetic factors. Some workers gave urine samples at the beginning and end of the working hours, in the evening and during the next morning. In 1993-1994 the samples were collected before and at the end of the shift. Samples were divided into 5-ml aliquots and stored at -20°C. Urine samples were analysed for 1-pyrenol by a HPLC method with fluorescence detection (Jongeneelen et al., 1987). The detection limit (twice the signal-to-noise ratio) of 1-pyrenol was 0.1 nmol/l and the precision (RSD) of the method was 3.0% obtained in 10 replicate analyses of a sample with a concentration of 10 nmol/l. The RSD 3.0% is the within-series variation. The variation of the results throughout the phases were followed by analysing a pooled urine sample at a
I99 (19971151-158
concentration level of 2.6 nmol/l of l-pyrenol. On the average, the RSD within a phase was 5.0% (N = 6, between-day variation) and between the phases 14% (N = 12, between-year variation). Specific gravity and creatinine were determined and used to standardise the results. 2.4. Statistical evaluation
Basic statistics of data were performed with the SPSS for Windows 6.1. software. Correlations of urinary 1-pyrenol with the pyrene concentrations in air were calculated using SAS procedures for personal computers. Pearson correlation coefficients (r) and linear regression equations were calculated, which are expressed in the form of y = ax + b, where x is the concentration of pyrene in air ( pg/m31 and y the urinary 1-pyrenol concentration ( ~mol/mol creatinine). 3. Results 3.1. Occupational
hygienic measurements
The mean concentration of BaP in personal samples of shift workers varied between 0.3 and 2.5 pg/m3 (Fig. 1). Pyrene concentration was at the same range, 0.5-3.5 pg/m3. In 1993-1994 the BaP exposure was on the level of 0.3 pg/m3. The new method was used for measurements in 1993 and, because it gives higher concentrations for pyrene, the decrease in exposure for pyrene is more distinct than Fig. 1 suggests. In 1992-1994 all the results were lower than the present Finnish occupational BaP exposure limit of 10 pg/m3. Most of the results were below 1 pg/m3 and e.g. in 1994 the maximum concentration (2.2 pg/m3> was found in the sample of a gas worker, who has the highest exposure among all the top side workers. However the average concentration of gas workers was below 1 pg/m3. In stationary samples the highest BaP concentration (5 ,ug/m3) was found on the bridge of the larry car. The PAH profile in all study phases was very consistent (Fig. l), e.g. in phase G there exists a good linear correlation (coefficient 0.990) between pyrene and the total PAH (the sum of 15 PAH compounds), hence it should be possible to use
L. Pp et al. /The Science of the Total Environment 199 (1997) 151-158
the pyrene as a marker compound and predict the concentrations of other PAHs by calculation. Napthalene was the main compound in the XAD samples and its concentration was at the level of 100 pg/m3. 3.2. Urinary metabolites of PAHs
The kinetics of urinary excretion of 1-pyrenol was studied in 1992 (phase E) from the samples of 10 workers, who gave urine samples before a shift, after the shift, in the evening and during the next morning. Also, the concentrations of pyrene in the breathing zone of workers were measured (range 0.09-2.6 pg/m3, mean 1.10 pg/m3). The concentration of 1-pyrenol was always higher af-
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ter the shift than before the shift. The workers were divided according to the concentration of pyrene in air, into the moderate exposure group (< 1.0 pg/m3, mean 0.41 pg pyrene/m3, n = 6) and to the fairly high exposure group (> 1.0 pg/m3, mean 2.12 pg pyrene/m3, n = 4). The mean concentrations of 1-pyrenol in urine in the moderate exposure group were 0.09 pmol/mol creatinine before the shift, 0.30 after the shift, 0.20 in the evening and 0.14 in the next morning (Fig. 2). The concentrations in the fairly high exposure group were 0.34, 0.69, 0.46, and 0.09 ~mol/mol creatinine, respectively. Table 2 summarizes all the urinary 1-pyrenol results and in Table 3 the results of 1993-1994 are divided in pro- and post-shift results. Large
PAH Wm”>
DUST (mg/m”)
1988
(N-,0)
lPhass
C, 1989
,N=68)
lPhars
D. 1090
(N=48)
OPhrsa
E, ,992
(N-67)
l Phase
F. 7993
(N-20)
rnPh.lSO
G, ,994
(NI66)
PAH compound Fig. 1. Average concentrations of identified PAH compounds and dust in personal samples of shift workers during different study periods. Abbreviations: NPH, Naphthalene; CHR, Chrysene; FL, Fluorene; BeP, Benzo[elpyrene; PHE, Phenanthrene; BkFLU, Benzo[klfluoranthene; ANT, Anthracene; BaP, Benzo[a]pyrene; PYR, Pyrene; diBahA, Dibenzo[a,h)anthracene; BaFL, Benzo [alfluorene; BghiP, Benzo[ghilperylene.
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199 (1997)
ISI-1%
1 = before shift
2 = after shift 3 = evening 4 = nex morning Fig. 2. Mean urinary excretion of l-pyrenol before a shift (11, after the shift (2), in the evening (3) and in the next morning (4) in the moderate exposure group 1 (< 1 pg pyrene/m3; n = 6) and fairly high exposure group 2 (> 1 Kg pyrene/m3; n = 4).
differences between arithmetic means and medians suggest 1-pyrenol concentrations distribute log-normally rather than normally. Before the start of the plant the mean concentration of urinary I-pyrenol was 0.3 pmol/mol creatinine (Table 2). The mean level of 1-pyrenol increased slightly during the first 2 years of production to 0.6 and 0.4 pmol/mol creatinine, and since 1990 Table 2 Urinary l-pyrenol ( pmol/mol Statistics Sampling Mean Median Max Min N Notes:
it was at the level of 0.2 pmol/mol creatinine. In F and G phases (1993-1994) the urinary l-pyrenol level increased slightly during working days, but the difference was not correlated with pyrene concentration in the air. It seems that significant correlation between urinary pyrenol and air pyrene appeared only in the first phase B (1998), when the exposure was at it’s highest. The corre-
creatinine) of coke workers and referents during study phases, all results
1987 (A>
1988 03
1989 (0
1989
1990
(ReD
CD)
1990 (ReD
1992 (E)
1993 (F)
1994 (G)
Pre 0.29 0.18 2.68 0.02 155
Pre 0.62 0.40 5.05 0.00 1.56
Pre 0.44 0.27 3.04 0.05 142
Pre 0.11 0.06 0.88 0.01 40
Pre 0.17 0.12 1.13 0.02 130
Pre 0.14 0.06 1.13 0.01 38
Post 0.17 0.07 1.53 0.01 172
Pre + 0.21 0.13 1.42 0.01 104
Post 0.14 0.08 2.35 0.01 323
Pre, pro-shift sampling; Post, post-shift sampling.
L. Pyy et al. /The Science of the Total Environment 199 (1997) 151-158 Table 3 Urinary 1-pyrenol ( ymol/mol creatinine) of coke workers in pre-shift and post-shift samples during study phases F and G Statistics
1993 (F)
1993 (F)
1994 (G)
1994 (G)
Sampling Mean Median Max Min N
Pre 0.16 0.08 1.29 0.01 54
Post 0.26 0.16 1.42 0.01 52
Pre 0.12 0.08 1.99 0.01 165
Post 0.16 0.10 2.35 0.01 159
lation equation was y = 0.15x + 0.67 and the correlation coefficient Y was 0.59 (P = 0.0001, N = 43). Urinary 1-naphthol concentrations determined for a small number of samples (N = 24) showed that no correlation between urinary and air concentrations can be found and 1-naphthol seems to be an uncertain marker for an assessment of air concentration of naphthalene. The mean of creatinine corrected l-naphthol values was 0.032 ~mol/mol creatinine (range 0.000-0.205, N = 20). For the before work samples the mean concentration was low (mean 0.011, range 0.000-0.038, N = 10) and the concentration increased significantly towards the after work samples (mean 0.056, range 0.000-0.205, N = 10).
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of occupational exposure limits (OEL) in several countries - in Finland the OEL value is 10 @m”. A comprehensive measurement programme has given reliable information of exposure and so the effect of technical improvements can be easily followed. The results reported to the staff of the coking plant have promoted technical protection. Furthermore, the information of the study has motivated the employers to correct the use of personal protection and to make working habits safer. Acknowledgements The authors express their gratitude to the Finnish Work Environmental Fund for its financial support. The authors wish to thank the staff and management of Rautaruukki Steel coking plant for excellent collaboration, and especially Dr. J. Kaisko and Mr. E. Muuruvirta for organising the collection of biological samples. Warm thanks are also due to the laboratory personnel of Oulu Regional Institute of Occupational Health and Department of Pharmacology and Toxicology, University of Oulu. References
4. Discussion Although the exposure levels already during the starting year were lower than at many older coking plants several technical improvements have further decreased the exposure. The mean exposure of the shift workers in 1993 was one-tenth of that in 1988. According to the ranking of Lindstedt and Sollenberg (1982) even the topside work at this coking plant belongs to a class ‘moderate BaP exposure’. The concentrations of 1-pyrenol (Tables 1 and 2) indicate very low exposure if compared to biological exposure limits 2.3 pmol/mol creatinine (Jongeneelen, 1992) or l-5 pmol/mol creatinine (Levin, 1995), proposed for coke oven workers. These biological exposure limits have been found to correspond to a BaP concentration of 2-5 pg/m3, which is the range
Bjorseth, A. and Ramdahl, T. (19851 Handbook of Polycyclic Aromatic Hydrocarbons. Marcel Dekker, New York, pp. 1-416. Buchet, J.P., Gennart, J.P., Mercado-Calderon, F., Delavignette, J.P., Cupers, L. and Lauwerys, R. (19921 Evaluation of exposure to polycyclic aromatic hydrocarbons in a coke production and a graphite electrode manufacturing plant: assessment of urinary excretion of l-hydroxypyrene as a biological indicator of exposure. Br. J. Ind. Med. 49, 761. Eisenhut, W., Friedrich, F. and Reinke, M. (1990) Coking plant environment in West-Germany. Coke Making Int. 1, 74-77. Hein, M., Friedricdh, F. and Eisenhut, W. (1994) Polycyclic aromatic hydrocarbons in the environment of coke oven plants. Coke Making 6(l), 40-43. International Agency for Research on Cancer (IARC) (1983) Polynuclear aromatic compounds. Part 1. Chemical, environmental and experimental data. In: IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Humans, Vol. 32. Lyon.
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International Agency for Research on Cancer (IARC) (19851 Polynuclear aromatic compounds. Part 4. Bitumens, coal tars and derived products, shale oils and soots. In: IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Humans, Vol. 35. Lyon. Jongeneelen, F.J. (1992) Biological exposure limit for occupational exposure to coal tar pitch volatiles at cokeovens. Int. Arch. Occup. Environ. Health 63, 511-516. Jongeneelen, F.J., Anzion, R.B.M. and Henderson, P.Th (1987) Determination of hydroxyiated metabolites of polycyclic aromatic hydrocarbons in urine. J. Chromatogr. 413, 227-232. Jongeneelen, F.J., van Leeuwen, F.E., Oosterink, S., Anzion, R.B.M., van der Loop, F. and Bos, R.P. (1990) Ambient and biological monitoring of cokeoven workers: determinants of the internal dose of polycyclic aromatic hydrocarbons. Br. J. Ind. Med. 47,454-461. Levin, J.O. (1995) First international workshop on hydroxypyrene as a biomarker for PAH exposure in man summary and conclusions. Sci. Total Environ. 163, 165-168. Lindstedt, G. and Sollenberg, J. (1982) Polycyclic aromatic hydrocarbons in the occupational environment. Stand. J. Work Environ. Health 8, 1-19. Makell, M. and Pyy, L. (1995) Effect of temperature on retention time reproducibility and on the use of pro-
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grammable fluorescence detection of fifteen polycyclic aromatic hydrocarbons. J. Chromatogr. A 699, 49-57. The National Institute of Occupational Safety and Health (NIOSH) (19851 NIOSH Manual of Analytical Methods NIOSH 5506-l. Cincinnati, Ohio. Ny, E.T., Heederik, D., Kromhout, H. and Jongeneelen, F. (1993) The relation between polycyclic aromatic hydrocarbons in air and in urine of workers in a Sijderberg potroom. Am. Ind. Hyg. Assoc. J. 54,277-284. United States Environmental Protection Agency (USEPA) (1982) Determination of Polycyclic Hydrocarbons in Municipal and Industrial Discharges; Method 610. Environmental Monitoring Systems Laboratory. Office of Research and Development, Cincinnati, OH. VanRooij, J.G.M., Bodelier-Bade, M.M. and Jongeneelen, F.J. (19931 Estimation of the individual dermal and respiratory uptake of polycyclic aromatic hydrocarbons of 12 coke oven workers. Br. J. Ind. Med. 50, 623-632. Vahlkangas, K., Pyy, L. and Yrjanheikki, E. (1992) Assessment of PAH-exposure among coke oven workers. Pharmacogenetics 2, 304-308. Yrjlnheikki, E., Pyy, L., Hakala, E., Lapinlampi, T., Lisko, A. and Vahakangas, K. (1995) Exposure to polycyclic aromatic hydrocarbons in a new coking plant. Am. Ind. Hyg. Assoc. J. 56,782-787.