Environ. Sci. Technol. 2002, 36, 4735-4740
Coplanar Polychlorinated Biphenyls (PCB) in Indoor Air M A R T I N K O H L E R , * ,† MARKUS ZENNEGG,† AND ROGER WAEBER‡ Swiss Federal Laboratories for Materials Testing and Research (EMPA), Department of Mobility and Environment, U ¨ berlandstrasse 129, 8600 Du ¨ bendorf, Switzerland, and Swiss Federal Office of Public Health (BAG), Chemical Products Division, 3003 Bern, Switzerland
Indoor air levels of coplanar polychlorinated biphenyls (mono- and non-ortho substituted PCB) of various buildings were determined. As a consequence of the presence of joint sealings containing PCB, total PCB concentrations in indoor air up to 4200 ng/m3 were detected (data based on a survey including 29 sampling sites). In a PCB contaminated industrial building, total indoor air PCB levels up to 13000 ng/m3 were measured. Typical PCB congeners in indoor air include PCB 28, PCB 52, and PCB 101. Concentrations of coplanar (dioxin-like) PCB have been determined for six different sites. The most abundant coplanar PCB congener in indoor air is PCB 118, followed by PCB 105, PCB 123, and PCB 77 in various order. Levels of coplanar PCB, expressed as toxicity equivalents (TEQ), do correlate well with the total indoor air PCB concentration: a total PCB level of 1000 ng/m3 corresponds to a concentration of coplanar PCB of 1.2 pg TEQ/m3. Based on this correlation and on an indoor air PCB level of 6000 ng/m3 (tentative guideline value for PCB in indoor air in Switzerland based on a daily exposure of 8 h), the maximum daily intake of coplanar PCB via indoor air was estimated to be 0.6 pg TEQ/kg body weight.
Introduction Polychlorinated biphenyls (PCB) possess toxic properties, resist degradation, and accumulate in terrestrial and aquatic ecosystems. PCB were used in heat transfer fluids, dielectric fluids (e.g. for capacitors of fluorescent lamp ballasts), hydraulic fluids, paints, coatings, ceiling tiles, and sealants. Joint sealings, usually based on polysulfide polymers, may contain up to 30% PCB as a plasticizer. Although a significant number of reports on indoor air contamination caused by joint sealings has been published in Germany for more than 10 years (1-17), these materials are still not generally recognized as possible sources for PCB. Only few reports on the impact of joint sealings containing PCB are available from other countries than Germany, e.g. from Sweden (18, 19), Finland (20), Australia (21), and Switzerland (22). Literature from the United States includes reports on sealants * Corresponding author phone: +41 1 823 4334; fax: +41 1 823 4041; e-mail:
[email protected]. † Swiss Federal Laboratories for Materials Testing and Research (EMPA). ‡ Swiss Federal Office of Public Health (BAG). 10.1021/es025622u CCC: $22.00 Published on Web 10/10/2002
2002 American Chemical Society
containing PCB in a reinforced-concrete drinking water reservoir (23), acute toxic effects in Rhesus Monkeys caused by PCB present in the concrete sealant on the cage floors (24, 25), and transfer of PCB from a silo sealant containing Aroclor 1254 into milk (26). All these reports show that sealants containing PCB can be critical in terms of indoor air quality, human health, and environment. Sealants which were manufactured before PCB were banned may contain significant amounts of PCB; they act as diffuse emitters of PCB and must be disposed of, correctly. Recently, joint sealings containing up to 30% PCB have been discovered in various public buildings in Switzerland, constructed between 1955 and 1975. Preliminary data from an ongoing study of the Swiss Agency for the Environment, Forests and Landscape (BUWAL) based on 450 samples from public buildings suggests that about half of all joint sealings contain more than 0.002% PCB, while a quarter of these samples contains between 1 and 30% PCB. In the same study, total PCB levels in indoor air up to 4200 ng/m3 caused by joint sealings were found (preliminary data based on a survey including 29 sampling sites). In an industrial building contaminated with PCB (former production of transformers), total PCB levels up to 13 000 ng/m3 were determined. Based on a tolerable daily intake (TDI) of 1 µg of PCB per kg body weight per day (27-30), a tentative guideline value (maximum tolerable concentration) for PCB in indoor air of 6000 ng/m3 was communicated by the Swiss authorities (31). This limit was set for buildings such as schools or offices, where people spend an average 8 h per day. For buildings such as residences, where permanent exposure can be assumed (24 h per day), the maximum tolerable concentration is 2000 ng/m3. The TDI of 1 µg of PCB per kg body weight per day, however, does only partly reflect the situation for indoor air, since the PCB congener distribution in indoor air is significantly different than the congener distribution of a typical technical PCB mixture, on which the TDI is based. PCB congeners with low degree of chlorination and high vapor pressure (such as PCB 28, PCB 52, and PCB 101) are the prominent species in air samples. For this reason, the total PCB content based on a routine determination of six standard PCB congeners (indicator congeners: PCB 28, 52, 101, 138, 153, 180) multiplied by a standard factor (such as 5) cannot be directly related to a certain amount of any technical PCB mixture. Considering the fact that coplanar PCB have been recognized to be an important factor for the assessment of the total exposure of human to dioxins and dioxin-like compounds through food (32), an assessment of the impact of coplanar PCB congeners in indoor air is just the next step in this direction (30). For these reasons, we decided to determine levels of coplanar PCB congeners as well as total PCB content in indoor air for various sites. According to the concentrations and toxicity equivalence factors (TEF) of the individual coplanar congeners, the toxicity equivalent (TEQ) was calculated and compared to the corresponding total concentration of PCB in order to see if a correlation exists. In this paper, we report data on total PCB content and levels of coplanar PCB in indoor air of various buildings, caused by joint sealings containing PCB and industrial use of PCB. Based on these data, the intake of dioxin-like PCB at the limit of 6000 ng/m3 for the total PCB concentration of indoor air is estimated and compared to the tolerable daily intake (TDI) of 1-4 pg/kg body weight for dioxins and dioxinlike compounds, issued by the World Health Organization (WHO) (32, 33). VOL. 36, NO. 22, 2002 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
9
4735
TABLE 1. Indoor Air Levels [ng/m3] of the Six PCB Indicator Congeners and Total PCB Contenta sample
location
PCB 28 [ng/m3]
PCB 52 [ng/m3]
PCB 101 [ng/m3]
PCB 138 [ng/m3]
PCB 153 [ng/m3]
PCB 180 [ng/m3]
total PCB [ng/m3]
A1 B1 B5 D1 E4
industrial building (PCB contaminated) public building (joint sealings with PCB) public building (joint sealings with PCB) public building (joint sealings with PCB) public building (joint sealings with PCB)
1100 280 270 10 440
1200 190 200 110 340
240 21 17 22 52
32 3.2 2.3 1.1 6.2
32 4 2.6 1.9 3.9
4.4 1 0.8 0.064 1.4
13000 2500 2500 720 4200
a
Site A1 represents an industrial building contaminated with PCB. Sites B1 to E4 represent rooms in various public buildings.
TABLE 2. Indoor Air Levels [ng/m3] of Coplanar PCB Congenersa sample
PCB 77 [ng/m3]
PCB 81 [ng/m3]
PCB 105 [ng/m3]
PCB 114 [ng/m3]
PCB 118 [ng/m3]
PCB 123 [ng/m3]
PCB 126 [ng/m3]
PCB 156 [ng/m3]
PCB 157 [ng/m3]
PCB 167 [ng/m3]
A1 B1 B5 D1 E4
4.1 0.71 0.61 0.024 0.65
0.37 0.12 0.065 0.0022 0.10
21 2.2 1.7 0.73 4.4
1.7 0.21 0.17 0.050 0.31
66 3.9 2.9 3.0 10
4.8 0.46 0.31 0.23 1.1
0.043
