R. K. BENTSEN,*J H. NOT0,f K. HALGARDf and S. 0VREB0*

Transcription

1 Ann. ocvup. llrg.. Vol. 42. No. 2. pp r 1998 Published by Elsevier Science Ltd on behalf of BOHS. All rights reserved Printed in Great Britain SI PII: S (97)00050-l S The Effect off Best-protective Respirator Mask amd tine Melevaimce off Work Category om Urimiary 1-Hydroxypyireiiiie Coraceimtratnoini nun JPAH Exposed Electrode Paste Flaunt Workers ~~ R. K. BENTSEN,*J H. NOT0,f K. HALGARDf and S. 0VREB0* (zbgpartment of Toxicology, National Institute of Occupational HealthJp.O. Box 8149 Dep, 0033 _Oslo, Norwqy^Jf Department of Occupational Hygiene, National Institute of Occupational Health, P.O. Box 8149 Dep, 0033 Oslo, Norway y ' Large amounts of polycyclie-aromatic hydrocarbons (PAH) are found in the work environment of electrode paste workers. Inhalation and skin uptake are both important routes for PAH exposure. We have studied the effect of dust-protective respirator masks by measuring urinary 1- hydroxypyrene as a biomarker for PAH exposure. Eighteen workers divided into work categories at the factory were monitored by personal air sampling and urinary l-hydroxypyrene every work shift for two consecutive weeks. In the second week of the study, the workers were encouraged to wear respirator masks persistently, which resulted in a significant reduction in urinary I- hydroxypyrene in end-of-shift samples (paired f-test, P = 0.009). When correcting urinary 1- hydroxypyrene for ambient air pyrene we found on average 41% reduction in urinary l-hydroxypyrene concentration in the second week of the intervention study. There was a work-category dependent variation in the correlation between end-of-shift urinary l-hydroxypyrene samples and pyrene measured in the breathing zone of the workers, most likely due to variable skin uptake of pyrene; the overall correlation coefficient was 0.26 (P = 0.015). The l-hydroxypyrene concentration in pre- and post-shift urine samples varied between 0.7 and 69.6 molmol creatinine in the normal work week, and depended on the work category. The particulate PAH exposure ranged from 0.6 to 21.4igm 3. The ratio of particulate pyrene to benzo a pyrene varied from 1.6 to 8.0 amongst the various work categories within the same plant. Multiple regression analysis showed that smoking and work day are explanatory variables for the concentration of l-hydroxypyrene in urine. Thirty-nine percent of the variation in the urinary l-hydroxypyrene level at the end of shift could be explained by the independent variables pyrene concentration in air, smoking habits, work day, use of respirator mask, work category and agevy, 1998 Published by Elsevier Science Ltd on behalf of BOHS. "^ INTRODUCTION PAH is associated with cancer primarily of the lung.,,,,.,,, r, and skin (IARC. 1983a; IARC. 1983b). Polycyclic aromatic hydrocarbons (PAHs) are formed _.. '.,.,,.,.,, , Occupational PAH exposure is usually monitored by incomplete combustion of organic matter and fossil,.,.,....,,.,,,..,,,,, by measuring the concentration of aerosols in ambient fuels, and are widely distributed throughout the., n...,,,. r.- r.,,..,,, air (Bjorseth and Becher, 1986). Biomonitonng of environment. PAHs are present in considerable n....,..,,,,.,. PAH exposure has a potential advantage over amounts in the work atmosphere r of several industries.....,..,... environmental monitoring because it estimates the where the most important sources are emission from.,, r,,,,...,, r,, internal dose from exposure through several routes, coal tar and pitch. A substantial amount of data has,..,..,,,.... e.g. skin and respiratory uptake (Lauwerys and Hoet. been reported on the carcinogenicity of a number of,nmv IT- IIAH u r ui 1 fc, 1993). Urinary PAH metabolites are easy accessible PAHs (IARC. 1987). and occupational exposure to... rnau TU, u r. v p v ' indicators of PAH exposure. The pyrene metabolite l-hydroxypyrene has been extensively studied as a biomarker for PAH exposure (Jongeneelen el ul., l987; :A~iuh7r to whom correspondence should be addressed. Tel.: Bo g aard and van SiUert < 1994 ; Buchet *' «> : Fax: ). The correlation between respiratory pyrene Received I May 1997: in final form 25 September exposure and urinary l-hydroxypyrene varies in

2 136 R. K. Bentsen et al. different plants with occupational PAH exposure (Boogaard and van Sittert. 1994: Jongeneelen el al ; Petry el al., 1996). Recent studies have shown a significant absorption of PAHs through the skin in addition to uptake of PAH through the lungs (Van- Rooij et al., b; Boogaard and van Sittert, 1994; Malkin el al., 1996). The excretion of urinary 1-hydroxypyrene in occupationally exposed workers is dependent on several factors in addition to pyrene exposure. Smoking has been shown to result in increased concentrations of l-hydroxypyrene in urine from coke oven workers (Jongeneelen et al., 1990) and aluminium workers (VanSchooten et al., 1995). Furthermore, the uses of protective clothing and respirator masks are important factors. Two recent studies have reported that protective clothing reduces the concentration of 1- hydroxypyrene in urine (Quinlan et al., 1995a; Van- Rooij et al., 1994a). But the effect of dust-protective respirator masks has not been extensively studied. Such masks are normally available at the worksite and should reduce the respiratory uptake of paniculate PAHs. We have examined the relationship between urinary 1-hydroxypyrene and pyrene exposure from workers at an electrode paste plant. When correcting for pyrene exposure we found a significant reduction in urinary 1-hydroxypyrene after use of dust-protective respirator masks in the second week in an intervention study. We also found a work-category dependent variation in the correlation coefficient between urinary I- hydroxypyrene and ambient air pyrene, likely to be caused by variable skin uptake of pyrene. MATERIALS AND METHODS Plant description and work-categories The samples were collected from workers in a plant which produces electrode paste for Soderberg electrodes. The electrode paste consists mainly of calcined anthracite with coal tar as a binder. The production is divided into several processes involving specific operators at each step. The mixers monitor the grinding of calcined anthracite in a ball-mill and the mixing of calcined ground anthracite with coal tar to produce electrode paste. The mixing process is supervised from a ventilated control room on the first floor of the production area. The mixers manually evaluate the plasticity of the heated paste every 15 minutes, and twice every shift samples are collected from the ballmill. The paste is heated to about 170 C during production. The electrode paste is then filled into various types of mould at the ground floor by the mould fillers. The work of the mould fillers includes manually adding waste paste to the moulds with shovels. Truck drivers transport the moulds to and from the filling point. Filled moulds are left to cool under water irrigation before being released from the moulds and wrapped in polystyrene for transportation. These tasks are carried out by the truck operators. Operators performing tasks like floor-sweeping, remelting of paste, or acting as production supervisors, were collectively grouped as miscellaneous. Study design Eighteen male workers representing the four work categories voluntary participated in the survey conducted in the spring of The operators were divided into three 8-hour shifts for day and night production. During two successive weeks these operators were monitored with personal air sampling devices. Each operator was equipped with a personal air sampler throughout his shift on the first four days of the two five-day work-weeks. Urine samples were collected before leaving for work and immediately after the shift, for all shifts in both weeks. Information about work-operation(s), smoking habits, age, number of years employed in the factory and use of respirator masks were gathered on personal questionnaires. In order to evaluate the PAH exposure for the various work categories, work-rotation was not practised during this study. Three females supervising the sampling acted as reference for exposure from staying in the production area. The reference persons were present at or near the production site at all shifts, both weeks, to administer personal questionnaires, assemble air sampling devices and collecting urine samples. During the work-tasks of the participating workers, protective masks were generally not worn. The exception is an occasional and brief (20-30 min.) use by some operators during mould filling of blocks (approximately 5% of the total production). During the second week of the study, described as the intervention week, each operator was encouraged to use a protective mask during all activities on the production site. A new mask was used during each shift. Respirator masks The respirator mask was classified as FFP3SL. protecting for exposure to solid and liquid particles. The mask is approved by the Norwegian Directorate of Labour Inspection (the Health and Safety Executive) according to CEN standards. Personal air sampling A 25 mm black graphite-filled polypropylene closed-face Gelman total dust sampler (Gelman Sciences, Ann Arbor. MI. USA. product no. 4376) with a 4mm orifice was used (Fig. 1). The sampler was equipped with an acrylic copolymer membrane filter with pore size 0.8im (Versapore 800. Gelman Sciences), and the empty space behind the filter was completely filled with an adsorbent. XAD-2 (SKC, Blandford Forum. UK). The mass of the adsorbent was approximately 0.4 g. The sampling was performed with Casella AFC 123 personal pumps (Casella. London. UK) operated at 21 min '. The sampling period was 7 8 h.

3 The effect of dust-protective respirator mask 137 Met Table 1. The PAH compounds used as standards and in the quantification of total PAHs. The 17 compounds are chosen according to NIOSH Manual of analytical methods (1994) Pump Fig. 1. Schematic diagram of the Gelman total dust sampler equipped with an adsorbent (XAD-2) placed behind the filter. Sample preparation and PAH analysis 3,6-Dimethylphenanthrene was added as internal standard to the samples before preparation. The filters were extracted with cyclohexane in an ultrasonic bath. PAH was extracted from the cyclohexane solutions into N,N-dimethylformamide (DMF) containing 3% water. The DMF phase was diluted with an equal volume of water and extracted with cyclohexane. The cyclohexane phase was dried with anhydrous sodium sulphate before concentrating the sample at 50 C under a stream of nitrogen. The XAD-2 was desorbed with 2.0 ml dichloromethane for 30 minutes. To avoid loss of the volatiles the desorbed solution was analysed directly without concentrating the sample. Dichloromethane, cyclohexane. N.N-dimethylformamide and sodium sulphate were obtained from Merck (Darmstadt. Germany). All samples were analysed with a HP 5890 series II gas chromatograph (Hewlett-Packard. Wilmington. USA) with (lame ionization detector (FID) and a CP-Sil 8 CB fused silica column (Chrompack, Raritan. USA, Cat.no. 7451, 25 mx 0.25 mm, df=0.25;im). Injections were made in the splitless mode with a 2min splitless time. Helium was used as carrier gas with a flow of 1 ml min '. The injector and FID temperatures were 300 C. The oven temperature was programmed as follows: 35 C for 2 min, from 35 C to 150 C with 6 Cmin ', from 150 C to 310 C with 10 C min ' and 310 C for 15min. The PAH compounds were identified comparing the GC-FID retention times with the retention times of the standards. An internal standard method was used for quantification of the PAH compounds. The PAH reference compounds used are listed in Table 1. Total ion chromatograms from GC-MS analysis of selected samples were also used for identification. A HP 5890 series II gas chromatograph connected to a HP 5971 mass selective detector (MSD) was used. The GC was equipped with a HP-5 column (Hewlett Packard. Wilmington, USA, Part No. 1909IJ m x 0.25 mm. df = 0.25 ;;m). The injector and MS Acenaphlhene" Acenaphthylene" Anthracene" Benz[«janthracene* Benzo[o]pyrene* Benzo[7]fluoranthene* Benzo[c]pyrene Benzo[i;]perylene Benzo[A]fluoranthene* Compound Chrysene Dibenz[a.;]anthracene* Fluoranthene Fluorene* Indeno[1.2.3-tr)pyrene* Naphthalene" Phenanthrene" Pyrene * = Carcinogenic (1ARC 1983),( = (gaseous) compounds mainly found in the adsorbent. interface temperatures were 300 C. The temperature program was as described above. The multiplier voltage was 70 ev. The analysis were performed in SCAN mode and mass range was amu. 1 -hydroxvpyrene determination All urine samples were collected in pre-labelled 100 ml polystyrene flasks and were stored at 20'C until analysis. 1-hydroxypyrene was determined in urine essentially after a method described by Jongeneelen el al. (1987). Spiked urine samples containing 10.20,40, 100and250nmoll 1-hydroxypyrene (Jansson Pharmaceutica, Geel, Belgium) were treated as unknown and used as standards for the quantitative determination of 1-hydroxypyrene. The urine samples were deconjugated with an enzyme mixture of glucuronidase and sulphatase (Boehringer Manneheim. Germany) overnight at 37 C and purified on C 8 Seppak cartridges (Waters, Millipore, Milford. MA) on a Waters Millilab Workstation (Milford, MA). The samples were eluted from the Sep-pack cartridges with 4 ml of methanol, evaporated to dryness and resuspended in 2 ml of methanol. Twenty <! of the extracts were injected onto a I50X 3.9 mm Nova-Pac C is column (Waters. Milford, MA) in a HPLC-system with a Perkin-Elmer LC240 fluorescence detector (Beaconsfield. UK). The extracts were eluted with a methanolwater gradient with column temperature of 40 C and flow rate 0.8 ml min '. The excitation wavelength was 242 nm and emission wavelength 388 nm. All values were corrected for creatinine content spectrophotometrically using the Jaffe reaction. Statistical analysis Exposure variables are presented with both the arithmetic mean and the median. The results had skewed distributions and were analysed using either the non-parametric Spearman rank correlation test or Pearson correlation analysis on natural log transformed data. The analysis were carried out on SPSS" 6.1 statistical software (SPSS Inc., Chicago).

4 138 R. K. Bentsen el at. Table 2. Personal characteristics of the 18 male electrode production workers who participated in the study Number of Number of Number of years smoking Age Employment Number of Number of Work category persons smokers (mean)" (mean years) years (mean) urine samples air samples Mixing Truck driving Mould filling Miscellaneous a Among the smokers only. For the multiple regression analysis the pyrene and 1-hydroxypyrene data were transformed by natural log to obtain normal distributions. The distributions of the residuals were analysed for normality. The statistical analysis of repeated measures was carried out using BM DP statistical software program 5V designed for repeated measures models (BMDP Statistical Software Inc., LA). Multiple regression analysis was also carried out on SPSS". For the statistical analysis weekday was treated as a variable from Monday (1) to Friday (5), and smoking as 0 or I. The project has been approved by a local ethical committee in accordance with the Helsinki Declaration of RESULTS Subjects The personal characteristics of the electrode paste plant workers are shown in Table 2. A total of 310 urine samples and 95 personal air samples were collected over the two working weeks of the study. In addition 12 urine samples were collected from the reference group in week 1 of the study. One outlier pyrene measurement and two outlier end of shift 1- hydroxypyrenes were considered improbable and excluded from the analysis. Personal air sampling The exposure concentrations of particulate PAH, pyrene and benzo[a]pyrene measured for the different work categories in the electrode paste plant are presented in Table 3. The ratio of pyrene to benzo[a]- pyrene varied between the work categories. The median exposure to particulate PAHs for all worksites was 2.8igm 3 (range igm 3 ). Mixers and mould fillers had similar levels of exposure to particulate PAHs. Nintyseven percent (SD 2%) of the total amount of PAHs were found in the adsorbent (mainly due to high amounts of volatile compounds like naphthalene and also acenaphthene, fluorene and phenanthrene). The median concentration of total PAH (particulate and gaseous) measured by personal samplers was 164.4igm 3 (range 20.2-l441.9(gm 3 ). The mould fillers had the highest pyrene exposure (particulate and gaseous) (Table 3). The median particulate pyrene concentration for all samples was 0.35(gm 3, which constituted 12% of the median concentration of the sum of particulate PAHs. The correlation coefficients (Spearman rank) between pyrene and PAH and benzo[a]pyrene are shown in Table 4 for all samples. The correlation coefficients varied between the work categories. Mixing had in general the best correlation; low correlation coefficients were found for mould filling. Using the Pearson correlation on log transformed data similar correlation coefficients were found, data not shown. Biological monitoring The concentration of l-hydroxypyrene in pre-shift samples ranged between 0.7 and 36.0<molmol creatinine, and for the post-shift samples between 5.6 and Table 3. PAH exposure measurement of samples collected with personal samplers. Median concentration (igm') of PAH over 10 work-days in the electrode paste plant Work category Pyrene (particulate and gaseous) Pyrene (particulate) BaP PAH (particulate) Mean ratio pyrenebap (particulate) Mixing Truck driving Mould filling Miscellaneous All work categories 3.4" ( )" (A' = I8r 2.0( ) (.-V = 44) 5.5( ) (V= 19) 2.5( ) (A'= 13) 2.8( ) (A' = 94) 1.04( ) (A'= 18) 0.2 ( ) (N = 44) 0.6( ) (A'= 19) 0.34( ) (N= 13) 0.35 ( ) (,V = 94) 0.09( ) (A' = 16) 0.15( ) (A' = 39) 0.24( ) (A'= 19) 0.30( ) (A'= 12) 0.18( ) (A' = 86) 5.2( ) (A'= 16) 2.0( ) (;V = 39) 5.0( ) (A'= 19) 3.2( ) (A'= 12) 2.8( ) (A'= 86) Median. h range and " number of samples.

5 The effect of dust-protective respirator mask 139 Table 4. Correlation coefficients (Spearman) for PAH air concentrations (igm 3 ). Pyrene (sum of paniculate and gaseous phase) Pyrene (paniculate phase) All work Truck Mould All work Truck Mould categories Mixing driving filling categories Mixing driving filling (N = 75-86) (V = 16) (;V = 32-40) (A' = 19) (N = 75-86) (;V = 16) (A' = 32-40) (N = 19) PAH (paniculate) PAH (total) BaP 0.66" 0.66" 0.44" 0.87' 0.51 b 0.75 a " " a 0.69" 0.47 a 0.91 a 0.79" 0.67 b 0.77" 0.48 b 0.68 a 0.76" a j ^ (molmol creatinine in the normal work-week. The median I-hydroxypyrene concentration of the post-shift samples in the normal work-week was 18 times higher than that of the reference group (1.03; SD 0.64; A' = 12). Table 5 shows the mean and median 1-hydroxypyrene concentrations in pre- and post-shift samples during the normal week and in the intervention week of the study. We found a reduction in urinary 1-hydroxypyrene due to use of respirator masks. A paired -test analysis on natural log transformed data (V = 128) showed a significant decrease (P = 0.009) in 1-hydroxypyrene concentration in end of shift samples in the intervention week compared to the previous week. Samples without a corresponding sample in both weeks were excluded from the analysis. The median concentration of pyrene (sum of particulate and gaseous phase) from the personal air samplers during the normal workweek was 2.58 gm 3 (mean 3.42, SD 2.54, N = 48) and in the intervention week 3.52 (gm 3 (mean 4.06, SD 2.96, A'= 45). By correcting each 1-hydroxypyrene (post-shift) by the pyrene concentration there was an apparent decrease in 1-hydroxypyrene concentrations for all work categories as shown in Fig. 2. Samples from operators not wearing masks in the intervention week are excluded in the calculations. All workers except the mixers experienced discomfort with the masks such as clamminess and difficulties with breathing during hard physical work. A multiple linear regression analysis was performed with 1-hydroxypyrene concentrations (end of shift samples) as the dependent variable. The independent variables were pyrene concentration in air, smoking habits (yesno), weekday, use of respirator mask, work category and age. Multiple regression analysis requires independence of the observations. We measured urinary I-hydroxypyrene each day for 18 workers over two work-weeks; a total of 89 post-shift urine samples with corresponding pyrene in air were collected. The independence of observations from the same worker might be questioned, at least those from the same week. A repeated measurement analysis was performed by the 5V program in BMDP and the results are shown in Table 6. We have performed the same analysis using the ordinary multiple regression analysis (SPSS statistical software) and found similar results. From this regression analysis 39 percent {adjusted R 2 = 0.39) of the variation in the urinary 1- Table 6. Multiple regression analysis for 1-hydroxypyrene concentrations (end of shift). Repeated measures (A' = 89). Variables Pyrene a Smoking habits' 1 Weekday' Respirator mask d Age Mould filler Constant Regression coefficient k (SE) 0.06 (0.02) 0.48(0.12) 0.21 (0.05) -0.22(0.11) 0.00(0.01) -0.04(0.13) 1.66(0.28) Z-score P a Pyrene (particulate and gaseous) (gm 3. b Smoking = I. non-smoking =0. ' Monday = 1 through to Friday = Normal week = 0. intervention week = 1. 1-hydroxypyrene and pyrene data are log transformed. Table 5. 1-hydroxypyrene concentration (imolmol creatinine) in urine during the normal workweek and the intervention week Work operation pre-shift Normal workweek post-shift increase(1) Intervention workweek pre-shift post-shift increase (2) Effect of mask (2-1) Mixing Truck driving Mould filling Miscellaneous All worksites 14.5(13.0) 9.1 (7.7) 12.2(10.7) 9.8 (9.6) 10.8(9.6) 20.1 (17.3) 18.5(17.1) 31.9(29.3) 17.0(14.5) 21.3(18.5) 5.6(6.8) 9.3 (9.2) 19.7(17.4) 7.2(10.5) 10.4(10.1) 10.0(10.9) 7.5(7.8) 6.4(7.1) 5.7(5.3) 7.3(7.1) 16.4(15.4) 18.7(16.2) 20.7(18.0) 12.9(9.9) 17.5(15.1) 6.4(5.7) 11.3(9.9) 14.3 (11.0) 7.3(5.9) 10.2(9.4) 0.8 (-1.1) 2.0 (0.7) -5.4 (-6.4) 0.1 (-4.6) -0.2 (-1.0) Arithmetic mean. Numbers in brackets show median.

6 140 R. K. Bentscn ct ul. Normal work week j 25 E a> c Intervention week ty;%\ CD b o 10 - CD a x o 5 - I Mixing I Truckdriving W Mould filling Miscellaneous Fig. 2. Boxplot of I-hydroxypyrene (end of shift) corrected for pyrene (sum of particulate and vapour phase) in the normal workweek and in the intervention week for each work category (yv = 64). The box encompasses the 25th through 75th percentiles and the capped bars indicate the IOth and 90th percentiles. The symbols mark all data outside the 5th and 95th percentiles. The arithmetic mean is marked with a dotted line and the solid line marks the median. hydroxypyrene level at the end of shift was explained in this model. The concentration of pyrene in ambient air and smoking habits were significant predictors for the concentration of urinary I-hydroxypyrene (Table 6). The use of respirator mask implies a reduction of the concentration of I-hydroxypyrene in post-shift urine, although of borderline significance (P = 0.04). Weekday (Monday I to Friday 5) describes an effect of over-the-week accumulation with an increased excretion of I-hydroxypyrene in urine. The working day of the week for monitoring of I -hydroxypyrene is therefore an explanatory variable for the concentration in urine. Age did not significantly contribute to the concentration level of I -hydroxypyrene. The work categories mixing, truck driving and mould filling were all tested in this model. The median daily values for the post-shift and preshift I-hydroxypyrene samples show an increase over the workweek (Fig. 3). When divided in work categories the median I-hydroxypyrene concentration for mixers and mould fillers accumulated over the work week, while the truck drivers, who had generally lower concentrations of I-hydroxypyrene. did not show any marked accumulation of I-hydroxypyrene in the pre-shift samples. The work category of the operator is of importance for the exposure to PAH. Particle size distributions of workers with different work categories were estimated using personal inhalable dust spectrometers (PIDS) over the whole work shift, data published previously (Note el al ). The results indicated that mould fillers are exposed to a relatively high percentage of fine aerosols with aerodynamic diameter (die) of less than 10.6<m (65-92%). Mixers were exposed to the largest particles, mainly coaldust (68% > lo.6m cac). Truck drivers were exposed evenly for particles of all sizes. Fig. 4 shows the correlation and regression coefficients between pyrene concentrations for the 8hour shifts and the corresponding I-hydroxypyrene as the difference between pre-shift and post-shift urines. The correlation coefficient varied considerably for the various work categories with the mould fillers having the highest correlation and mixers the lowest coefficient. The same analysis were performed with post-shift urinary I-hydroxypyrene samples and gave essentially the same results, with mould fillers having the best correlation (k = R2 = 0.16; and mixers the poorest (k = R2 = 0.038). The correlation between 1-hydroxypyrene in post-shift samples and pyrene in ambient air (all samples) was low with a regression coefficient of 0.85 (r = 0.26: R2 = 0.07: P = 0.015: N = 88). Similar results were found when testing pyrene and the difference in I-hydroxypyrene in urine samples collected before shift and at the end of shift (A- = = 0.29: R2 = 0.08: P = 0.006: N = 87). The correlation between breathing zone pyrene and the next day pre-shift I-hydroxypyrene had a regression coefficient of 0.61 ( = R2 = P = N = 86). The variables in this regression analysis were not log transformed as the residuals after analysis were near normal distributed. There were 67% smokers among the workers. The average I-hydroxypyrene concentration in pre-shift samples was 8.55mol mol creatinine (SD 6.96:,V = 50) for non-smokers and for the smokers 9.40mol mol creatinine (SD 6.50: N= 109). The!

7 The effect of dust-protective respirator mask Normal workweek Intervention week ro a> _o 20 "o Postshift 1-hydroxypyrene "o CD c a) Mon Tue Wed Thu Fri Mon Tue Wed Thu Fri Day Preshift 1-hydroxypyrene Fig. 3. Median concentration of l-hydroxypyrene in pre-shift and end of shift samples for each day in the normal workweek and in the intervention week for all work categories. average post-shift l-hydroxypyrene concentration urinary l-hydroxypyrene between pre-shift and postwas imolmol creatinine (SD 7.70; N = 47) for shift was 2.8 times higher in the smokers compared to the non-smokers and about 1.5 times as high for the the non-smokers (all work categories). Fig. 5 shows smokers (21.88; SD 11.35; N = 102). The difference in that there are differences between smokers and non Pyrene ugm 3 Fig. 4. Scatter plot of urinary l-hydroxypyrene and total pyrene (sum of particulate and vapour phase) with regression curve. The l-hydroxypyrene value is the difference in concentration between pre-shift and post-shift samples.

8 (42 R K " n t s e n el al. Fig. 5. Urinary 1-hydroxypyrene (difference between preshift and post-shift) divided in groups of smokers and nonsmokers for four work categories (N = 303). The box encompasses the 25th through 75th percentiles and the capped bars indicate the IOth and 90th percentiles. Values falling outside this range are indicated by circles. The arithmetic mean is marked with a dotted line and the solid line marks the median. smokers within each work category. The smokers had higher 1-hydroxypyrene concentrations than nonsmokers in both samples collected after shift and in next-day pre-shift samples indicating similar excretion-rates for the smoking and non-smoking workers. DISCUSSION in this study we have examined several factors that affect the concentration of 1-hydroxypyrene in urine from PAH exposed workers. We found a significant reduction in urinary 1-hydroxypyrene after use of dust-protective respirator masks. There was a work category dependent variation in the correlation coefficient between urinary 1-hydroxypyrene and pyrene measured in the breathing zone of the electrode paste plant workers. This indicates variation in PAH exposure routes. The ratio between pyrene and benzo[a]pyrene varied considerably between the work categories. The best correlation between urinary 1-hydroxypyrene and breathing zone pyrene was found in sam- The mould fillers had the highest concentrations of urinary 1-hydroxypyrene. This group were also exposed to the highest concentrations of pyrene measured in the breathing zone of the workers. The high urinary 1 -hydroxypyrene concentrations of the mould fillers may be additionally influenced by the physically demanding work leading to increased inhalation. In general, the urinary 1-hydroxypyrene concentrations were comparable to concentrations measured by Petry el al. (1996) at a carbon anode plant, but were considerably higher than measured in coke oven and graphite electrode production workers (Jongeneelen el al., 1990; Buchet et al., 1992), creosote (VanRooij el al., 1993a) and aluminium workers (VanRooij el al., 1992). We have in this study measured the concentration of 1-hydroxypyrene in urine from 18 workers each workday over two weeks. By using repeated measurement analysis we have included the following variables in a multiple regression model: pyrene air monitoring, use of respirator mask or intervention week, weekday, work category, smoking and age. In this model, the use of respirator mask did reduce the urinary 1-hydroxypyrene concentrations, but only with borderline significance. However, the protection masks reduced the concentration (median) of 1-hydroxypyrene in postshift urine by an average of 4 1 % when the data were corrected for ambient pyrene concentration. Pyrene is a moderately volatile PAH which is normally found approximately 50% in the gaseous phase in workroom air (Bjerseth er al ; Leinster and Evans. 1986). Therefore a large percentage of the ples from the mould fillers. A reasonable explanation for this finding is that the main pyrene uptake for the mould fillers is via the lungs and that absorption of pyrene through the skin is less important, whilst mixers and truck drivers had a larger fraction of skin absorption. VanRooij el al. (1993b) and Quinlan el al. (1995b) estimated skin absorption to account for between 70 and 75% of the total absorbed dose of pyrene for workers in a coke oven and a coal liquidification factory, respectively. For workers in the aluminium industry VanRooij el al. (1992) found a better correlation between urinary 1-hydroxypyrene and pyrene contamination on pseudo-skin exposure pads than between 1-hydroxypyrene and concentration of breathing zone pyrene. An additional factor that can lead to variation in pyrene uptake is the particle size of the pyrene aerosol (aerodynamic size d.df.). The size-distribution of PAH-containing particles for the mould fillers is likely to result in relatively high uptake due to deposition in the tracheobronchiai and alveolar fractions of the lung. Mixers, however, were exposed to a high fraction of particles larger than 10.6 jim dac, predominantly coaldust, which typically deposit in the nasopharalyngeal region, resulting in relatively lower uptake. These large particles may be swallowed and possibly absorbed in the gastrointestinal tract (Klaassen, 1980). Truck drivers were exposed evenly for particles of all sizes.

9 The effect of dust-protective respirator mask 143 pyrene is not hindered by the dust-protective respirator mask. To our knowledge no similar studies on the effect of dust-protective respirator masks has been reported, although Jongeneelen et al. (1990) registered on a small number of samples that the use of airstream helmets reduced the urinary 1-hydroxypyrene by an average of 43% in coke oven workers. Both the multiple regression analyses and the data for smokers and non-smokers summarised in Fig. 5 show that smoking increases the concentration of urinary 1-hydroxypyrene. Several authors have reported a synergistic effect of smoking on urinary 1-hydroxypyrene levels among occupational PAH exposed workers (Jongeneelen et al., 1990; VanSchooten et al., 1995; 0vreb0 el al., 1994). The average concentration of 1-hydroxypyrene in samples collected by the end of the shift was 1.5 times higher for smokers than nonsmokers. Smoking and dietary PAH intake increase the excretion of 1-hydroxypyrene in urine (VanRooij el al., 1994b), but this increase is small compared to occupational PAH exposure and can not explain the large increase in our results. Smoking induces specific P-450 enzymes (Sesardice«., 1996) and the increased enzyme activity can result in increased 1-hydroxypyrene concentrations in urine from PAH exposed workers. Smokers may have higher uptake of PAH than non-smokers since long-term smoking appears to reduce mucociliary clearance (Wanner, 1985) thereby reducing the efficiency of clearance of PAH-containing aerosols from the lungs. For risk evaluation it is important to know the ratio between pyrene and the more carcinogenic PAHs such as benzo[a]pyrene, since pyrene and 1-hydroxypyrene are devoid of any significant carcinogen activity. Jongeneelen (1992) have suggested a biological exposure limit of urinary 1-hydroxypyrene of 2.3imolmol creatinine for coke oven PAH exposure resulting in a relative risk of lung cancer of approximately 1.3. These calculations are based on coke oven plant exposure data from personal air samples where a ratio of pyrene to benzo[a]pyrene of 1.6 was found. In the electrode paste plant we found that the mean ratio of the paniculate form of pyrenebenzo[a]pyrene varied from 1.6 to 8.0 between the various work categories. This ratio is of relevance for risk evaluation because the urinary 1-hydroxypyrene level has a different implication for the various work categories in the same plant. The correlation coefficient between breathing zone pyrene and urinary 1-hydroxypyrene in samples collected before shift the next day were similar to the correlation for urinary 1-hydroxypyrene in samples collected at the end of shift. But because the 1-hydroxypyrene concentration is lower in pre-shift urine samples, sampling of urine at the end of shift is preferable. We have found a tendency to accumulation of pyrene (1-hydroxypyrene) during the workweek (Fig. 3), and the same conclusion can be drawn from the multiple regression analysis. The half-life of 1-hydroxypyrene is long enough to give accumulation as pointed out by Lauwerys and Hoet (1993) and Buchet et al. (1992). Therefore, sampling of urine before shift the next day (16 hours) may replace end of shift urinary 1-hydroxypyrene measures in this factory. There are growing concerns among PAH exposed workers about the potential health hazard from skin contact with PAH containing materials (Malkin et al., 1996), an exposure route that would be missed by air sampling alone. The biomarker 1-hydroxypyrene reflects the total exposure more accurately than environmental monitoring, and several authors consider urinary 1-hydroxypyrene to be a valuable biomarker for occupational PAH exposure (Levin, 1995; Malkin et al., 1996; Quinlan et al., 1995). Occupationally inhalatory PAH exposure has been related to increased lung cancer risk. Furthermore it has been shown that topical treatment with PAH on mouse skin results in PAH-DNA adducts in lungs (Randerath et al., 1988), and therefore lung cancer risk following skin uptake can not be ruled out. In summary, we have found that dust-protective respirator masks reduced the PAH uptake among workers at an electrode paste plant shown as a reduction in urinary 1-hydroxypyrene concentration. There was a work category dependent variation in the pyrenebenzo[a]pyrene ratio and variation in the correlation coefficient between urinary 1-hydroxypyrene and breathing zone pyrene. 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