Ann. occup. Hyg., Vol. 48, No. 1, pp. 51-55, 2004
© 2004 British Occupational Hygiene Society
Published by Oxford University Press
Worker Exposure to Polychlorinated Biphenyls in Elastic Polysulphide Sealant Renovation
1 Institute of Occupational Health, Topeliuksenkatu 41 aA, FIN-00250 Helsinki, Finland; 2 Uusimaa Regional Institut of Occupational Health, Arinatie 3, FIN-00370 Helsinki, Finland; 3 Tampere Regional Institut of Occupational Health, Uimalankatu 1, FIN-33100 Tampere, Finland
Received 7 February 2003; in final form 15 July 2003
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Worker exposure to polychlorinated biphenyls (PCBs) in renovation of prefabricated houses was assessed by biological monitoring of 24 PCB congeners including the 10 most abundant PCBs in elastic polysulphide sealants. Serum samples from 22 exposed and 21 non-exposed men were analysed using gas chromatography–mass spectrometry with negative chemical ionization. Total PCB concentration of 24 PCB congeners in workers’ serum varied between 0.6 and 17.8 µg/l (mean 3.9 µg/l, median 1.9 µg/l). The Finnish upper reference limit for occupationally non-exposed persons (3 µg/l) was exceeded in the serum samples of 10 workers. Concentrations for non-exposed persons were 0.3–3.0 µg/l (mean 1.7 µg/l, median 1.5 µg/l). The concentration for the sum of the 10 most abundant PCB congeners in elastic polysulphide sealants in serum samples taken in autumn after the renovation season was 2–10 times higher than in samples from the same workers (n = 5) taken in the previous spring. The concentrations of PCB congeners PCB 28, 52, 77, 101, 138, 153 and 180 in hygienic samples taken from the breathing zone of the workers were low, ranging from not detected to 3.1 µg/m3. The concentrations of PCB 28 and 52 in sera were positively correlated with the concentrations in air samples taken from the breathing zone of six workers (r = 0.70 and 0.80).
Keywords: occupational; exposure; polychlorinated biphenyls; renovation; elastic polysulphide sealants
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Mastic sealants are used to seal up the joints between prefabricated units. In Finland, sealants containing polychlorinated biphenyls (PCBs) as softeners were used from the 1950s to the 1970s. The sealants consisted of two-components with polysulphide polymer as a binding agent. The curing agent added in the polymer contained lead oxide. The amount of PCB in sealants has been reported to be between 7 and 25% (w/w) and the amount of lead up to 5%, respectively (Pyy and Lyly, 1998). PCBs used in sealants have been mainly of Aroclor 1260 or Aroclor 1254 type (Rantio et al., 2001). Upon ageing, the sealants lose their elastic properties and have to be replaced. In Finland, the lifetime is about 20–30 yr because of the weather conditions (Rautiainen, 1989). PCBs have been found in the soil near prefabricated buildings in amounts exceeding the limit value for contaminated soil (0.5 mg/kg) (Puolanne et al., 1994; Jansson et al., 1997; Pyy and Lyly, 1998; Hellman, 2000). Due to their chemical stability and lipophilicity, PCBs accumulate readily in the body, and at high levels (60–3300 µg/l) they may cause harmful health effects, e.g. liver cancer, melanoma, hyperceratosis (IPCS, 1993; Anonymous, 2000). Renovation workers’ exposure to PCBs has been evaluated by work hygiene measurements (Sikander et al., 1999). Biological monitoring has also been used to assess worker exposure to PCBs in capacitor and waste disposal work (Luotamo, 1988, 1991; Luotamo et al., 1991, 1993; Luotamo and Aitio, 1994), where exposure assessment of the workers was done with PCB standards containing not more than five chlorine atoms. When it became evident that renovation and waste disposal workers might be exposed to higher chlorinated PCBs, the need was seen to widen the number of PCB congeners routinely analysed. In this study, we have chosen a variety of PCB congeners also containing the characteristic congeners used in sealants.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Participants
The study group consisted of 22 men who had renovated prefabricated houses for periods from 3 months to 37 yr. The age of the workers ranged from 21 to 61 yr. The 21 non-exposed male controls aged 30–57 yr worked in the Institute of Occupational Health on different tasks. The participants were interviewed about their work and other personal characteristics known to be related to PCB serum concentrations. Informed consent was obtained from the participants and the design of the study was approved by the Ethics Committee of the Finnish Institute of Occupational Health. The serum samples were collected in 1999–2000.
Sampling
The renovation season lasted from April to November and consisted of several work periods. Fasted serum specimens of 10 ml were collected at the end of the sealant renovation period from all 22 participants and the controls in the morning before a work shift. In addition, seven of the workers gave a fasted serum sample after the start of the renovation season in the spring. Venous blood was taken in pre-cleaned plastic sampling tubes. The serum was separated by centrifugation, frozen immediately and stored in a freezer (–20°C) until further treatment. Whole blood samples were taken for the lead analyses. Because the lead concentrations were low, under the limit value for occupationally non-exposed persons (0.3 µmol/l), they are not further discussed in this paper.
Gas chromatograph
A Hewlett-Packard 6890 gas chromatograph equipped with an HP-5973 mass-selective detector with negative chemical ionization (133 eV) using methane as reagent gas was used (Kontsas and Pekari, 2003).
Materials
The PCB standard solution (C-CCSEC) was purchased from Accustandard (New Haven, CT), solid PCB 30, 33, 47, 74, 116 and 169 from Dr Ehrensdorfer (Augsburg, Germany).
Analytical procedure
The PCB standard solutions and the samples were prepared as described earlier (Kontsas and Pekari, 2003). Briefly, a 2 ml volume of serum sample was mixed with 2 ml of internal standard in methanol and 6 ml of diethylether–hexane. The organic layer was concentrated to 2 ml and mixed with 2.5 ml sulphuric acid. The organic layer was dryed on sodium sulphate and 1 ml of sample was added to a silica column. The PCBs were eluted with 2 ml of hexane. The sample was concentrated to 250 µl and transferred to autosampler bottles for gas chromatography. The following 24 PCB congeners (IUPAC nomenclature) were determined: PCB 8, 18, 28, 33, 44, 47, 52, 66, 74, 77, 101, 105, 118, 126, 128, 138, 153, 169, 170, 180, 187, 195, 206 and 209. In the mastic sealants used, the 10 main components are PCB 28, 52, 77, 101, 118, 126, 138, 153, 169 and 180. The other 14 congeners of the total 24 analysed are usually found in biological samples.
Since 1993 the laboratory has participated successfully in a certification exercise ‘QualiMed Quality Assurance in Occupational and Environmental Medicine’ organized by the Institute for Quality Management in Medicine (Erlangen, Germany). The PCB congeners in the programme are PCB 28, 52, 101, 138, 153 and 180.
Air sampling
Air samples from the breathing zone of six workers, who also gave a serum sample, were taken in during renovation periods in 1999 and 2000. The air samples were collected in XAD-2 tubes (SKC 226-30), with a glassfibre filter placed in front of the tube, or in OVS tubes (SKC 226-30-16, containing both an XAD layer and a glassfibre filter). Pumps were used to obtain a flow rate of 1–2 l/min through the tubes. The sampling time was between 15 min and 6 h, depending on the duration of the work, which consisted of drilling and grinding. PCB congeners (PCB 28, 52, 77, 101, 138, 153, 180 purchased from Dr Ehrensdorfer, Augsburg, Germany) used for sealant analyses in the Regional Institutes of Occupational Health in both Tampere and Uusimaa were extracted with hexane and analyzed using a gas chromatogram equipped with an electron capture detector or mass-selective detector.
Statistics
For concentrations lower than the quantification limit, half of the limit value was used in statistical calculations.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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PCB concentrations in the breathing zone of six renovation workers participating in our study ranged from not detected to 3.1 µg/m3 (Table 1). PCB concentrations in renovation workers’ and controls’ sera are given in Figures 1 and 2. The total PCB concentration (sum of 24 PCB congeners) in workers’ sera varied between 0.6 and 17.8 µg/l (mean 3.9 µg/l, median 1.9 µg/l). The concentrations of the same 24 PCB congeners for non-exposed persons were 0.3–3.0 µg/l (mean 1.7 µg/l, median 1.5 µg/l).
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Figures 1 and 2 give the distribution of low (four or fewer chlorine atoms in the molecule) and high chlorinated (more than four chlorine atoms in the molecule) PCB congeners in the workers’ and controls’ sera. Most of the PCB burden is due to higher chlorinated congeners. The contribution of higher chlorinated congeners to the total burden varied from 45 to 100% for the exposed workers and from 40 to 100% for the controls. For the workers, the mean concentration of low chlorinated congeners was 0.4 µg/l and median 0.2 µg/l; the mean of the high chlorinated congeners was 3.5 µg/l and median 1.6 µg/l. For the controls, the mean concentration of low chlorinated congeners was 0.3 µg/l and median 0.05 µg/l; both the mean and median of the high chlorinated congeners were 1.4 µg/l.
Seven workers gave a serum sample in both the spring and the autumn. Five persons worked through the summer and had elevated total PCB concentration of the congeners PCB 28, 52, 77, 101, 118, 126, 138, 153, 169 and 180 in serum after the renovation season (Fig. 3). The workers had replaced sealants weekly or monthly during the summer. Person 3 was the only one who consumed fish more than three times a week. The higher concentrations in the autumn samples were due to PCB congeners 118, 138, 153 and 180. Of the two persons whose PCB concentration had decreased (not shown), the first had carried out daily sealant replacements before the sampling in the spring and only irregularly during the summer season. The PCB concentration in his serum fell from 13.9 to 9.8 µg/l. The other worker (from 6.8 to 1.5 µg/l) had not worked at renovation sites at all after the first sampling. A relation between the concentrations in serum and the levels found in the breathing zone was noted only for PCB 28 (r = 0.70, P = 0.1, n = 6) and PCB 52 and (r = 0.80, P = 0.06, n = 6).
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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The total PCB concentration found in the serum of renovation workers was increased compared to non-exposed persons. Ten of 22 serum samples had higher PCB concentrations than the Finnish upper reference limit for occupationally non-exposed persons (3 µg/l) (Luotamo, 1995). This value has been set for the sum of 12 PCB congeners: PCB 8, 18, 28, 33, 44, 47, 66, 74, 77, 87, 97 and 121 with two to five chlorine atoms in the molecule. If the worker exposure (Figure 1) is compared to the limit value for the sum of these 12 PCB congeners, all the concentrations in the samples are below this limit value, although the total PCB concentrations of all the 24 congeners may reach a level of 18 µg/l. In our study, congeners of higher chlorination grade were analysed as well and most of the PCB burden was due to higher chlorinated congeners for both workers and controls. For occupational exposure there is no biological action limit for PCBs in Finland. If one compares the PCB levels found in renovation workers to the levels measured after accidental exposures (Luotamo et al., 1993), the exposure in renovation work is low. In the case of fire or arcing of capacitors and transformers the concentrations of PCBs were up to 50 µg/l serum.
In a Swedish study (Noren et al., 1999), 16 congeners (PCB 28, 52, 101, 105, 114, 118, 122, 123, 138, 153, 156, 157, 167, 170, 180 and 189) were analysed from the plasma of non-exposed persons and the sum of congeners varied from 2.5 to 4.3 µg/l, which is a little bit higher than the concentrations found for the 24 PCB congeners in the sera of the controls in this study. Teacher exposure to PCBs in German schools was assessed by six PCB congeners (PCB 28, 52, 101, 138, 153 and 180) (Gabrio et al., 2000). These congeners were also found in indoor air at concentrations of 1.6–11 µg/m3. PCB 28 and 52 accounted for nearly 90% of the total concentration in air. The concentrations of PCB 28 (0.098 µg/l) and 101 (0.084 µg/l) in blood were moderately elevated in some schools, but the concentrations of PCB 138 (mean 0.010 µg/l), 153 (mean 0.016 µg/l) and 180 (0.012 µg/l) were on the same level as in controls (Gabrio et al., 2000). In our study, the concentration of PCB 28 varied from not detected to 0.4 µg/l for both the exposed workers and the controls. The concentration of PCB 101 ranged from not detected to 0.5 µg/l for exposed workers. PCB 101 was not detected in the samples of the controls. The sum of PCB 138, 153 and 180 were 0.3–12 µg/l for the workers and 0.2–2.4 µg/l for the controls. Low chlorinated PCBs, being more volatile, are the main source of exposure via indoor air. In our study, only the concentrations of PCB 28 and 52 in breathing zone air samples were positively related with the concentrations of these congeners in workers’ sera. However, there were only six workers whose breathing zone PCB concentrations were measured, and for PCB 28 several air concentrations were below the limit of quantification. During grinding PCB 101, 138, and 153 were the main components due to the dust formed in this working stage.
Due to the slow elimination of PCBs in humans the PCB concentration in serum describes a person’s long-term exposure better than the air measurements. In renovation work the workers are more likely to be exposed to PCBs in the grinding dust. The amount of high chlorinated (more than four chlorine atoms) PCBs correlated slightly with the time for which subjects had been involved in renovation work (r = 0.53, P = 0.005, n = 22).
As in a Swedish study ( Sjödin et al., 2000), in our study PCB concentrations were found to increase with the age of the renovation workers. Kappos et al. (1998) have proposed that the biological limit value should be given age-specifically as concentrations of PCB 138, 153 and 180. The concentration in plasma for the sum of these congeners varied from 3.2 to 12.2 µg/l in persons aged 18–65 yr. According to this classification, three of the workers in our study had PCB concentrations up to three times the corresponding German limit values. The concentrations of all the controls were below these limits.
The biological monitoring method proved to be a good way to assess worker PCB exposure. Samples taken before and after the renovation season showed that exposure takes place to some extent despite appropriate working equipment, methods and personal protection.
Acknowledgements—We thank Ms Eevi Nieminen and Ms Kirsti Nilsson for blood sampling and Ms Tuula Karttunen for skilful technical assistance. Financial support for this study from the Finnish Work Environment Fund is gratefully acknowledged.
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FOOTNOTES |
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* Author to whom correspondence should be addressed. Tel: +358-9-47472857; fax: +358-9-47472208; e-mail: helena.kontsas{at}ttl.fi
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