Pentachlorophenol in indoor environments. Does a single measurement of air and dust concentrations represent the contamination?† Ju�rgen Schnelle-Kreis,*ab Hagen Scherb,c Istvan Gebefu�gia and Antonius Kettrupab aGSF–National Research Center for Environment and Health, Institute of Ecological Chemistry, Ingolsta�dter Landstrasse 1, D-85758 Neuherberg, Germany. E-mail: jurgen.schnelle@gsf.de bDepartment of Ecological Chemistry and Environmental Analytical Chemistry, Technical University Munich, D-85358 Freising, Germany.cGSF–National Research Center for Environment and Health, Institute of Biomathematics and Biometry, Ingolsta�dter Landstrasse 1, D-85758 Neuherberg, Germany Received 30th March 1999, Accepted 12th May 1999 In order to be able to make a decision, as to whether a room or building has a health-endangering pentachlorophenol (PCP) concentration, usually the PCP concentrations in air and settled dust are measured. The variability of the PCP concentration in indoor air and dust was studied. Air and dust samples were taken from 75 rooms in 30 buildings with suspicion of application of PCP-containing wood preservatives.Sampling was repeated four times within 18 months.Thirty-six rooms were reconstructed within the study; 39 rooms had unchanged contamination status during the study. The four times repeated measurements of PCP concentrations in air and dust in these rooms showed large variations of the measured values. The variability of the results is to a large extent in the same range as the measured values.The observed relative standard deviation of the PCP concentrations in air and dust does not depend on the average PCP concentration detected in the individual rooms. population of the USA. Today, as a result of the decrease in Introduction PCP concentrations in blood and urine and the long persistence Until the 1980s, pentachlorophenol (PCP) was one of the of PCP in treated wood, indoor air can be assumed to be a most heavily used pesticides worldwide.It has been registered more important source of PCP exposure for people living in for use as an insecticide, herbicide, algicide, fungicide, wood houses with PCP-treated wood. preservative, germicide, and molluscicide.1 Since 1987, wood PCP in indoor environments is measured mainly by air or preservatives and other pesticides containing PCP have no dust analysis.Air analysis has many restrictions. It is known longer been available for home and garden use in the USA. that PCP concentrations in indoor air are variable to a high Nowadays, in the USA only certified applicators can purchase degree, depending on room ventilation, humidity, and temperaand use PCP. It is still used as a wood preservative for power ture.17,18 Moreover, air analyses can only measure the momenline poles, railroad ties, cross arms, and fence posts.In many tary concentration of PCP. Therefore, valid air analysis is time other countries the production and use of PCP are prohibited, consuming and expensive. On the other hand, the investigation e.g. in Germany since 1989.2 of settled dust is a proven and simple screening analysis for PCP is eYciently absorbed by the lungs, skin,3,4 and gastroindoor contamination with semi-volatile compounds.Krause intestinal lining.5 The main exposure to PCP is by dermal and Englert19 found a high correlation (r=0.8) between PCP contact, by inhalation of PCP from oV-gassing of treated concentrations in dust from vacuum cleaner bags and PCP wood products and ingestion of contaminated food and water.concentrations in urine. Meissner and Schweinsberg20 reported Moreover, PCP is a metabolite of the endogenous conversion a correlation of PCP concentrations in passively deposited sus- of hexachlorobenzene,6,7 pentachlorobenzene,8 pentachloroanpended particulate matter of houses with PCP-treated wood isole,9,10 and possibly hexachlorocyclohexane ( lindane) and and the concentration of PCP in the urine of exposed persons.pentachloronitrobenzene.11 In our study we found a significant correlation of PCP The health eVects of exposure to PCP were summarized by concentrations in air and freshly settled dust21 and significant the Agency for Toxic Substances and Disease Registry.1 Longcorrelations of PCP concentration in air with PCP concen- term exposure to low levels can harm the liver, kidneys, blood, trations in blood and urine.22 lungs, nervous system, immune system, and gastrointestinal In the German ‘‘PCP Guideline’’ of 1997, PCP concen- tract.The International Agency for Research on Cancer’s trations in air higher than 0.1 mg m-3 and concentrations in classification of PCP is possibly carcinogenic to humans dust higher than 1 mg kg-1 indicate the need for further (Group 2B).12 Recently, the hormonal action of PCP has been measurements (human monitoring).23 under discussion.13–15 The aim of this investigation was to determine the variability In the late 1980s, Hattemeyer-Frey and Travis16 concluded of PCP concentration in the indoor air and in (freshly) settled that food had major importance for human intake of PCP. dust samples.Our goal was to answer the question of whether Especially fruits, grains, and vegetables were assumed to there is a way to discover the ‘‘real contamination’’ of a room account for 99.9% of human exposure to PCP in the general or building and, if possible, how many measurements are necessary to reach this target.†Presented at AIRMON ’99, Geilo, Norway, February 10–14, 1999. J. Environ. Monit., 1999, 1, 353–356 353Experimental The concentrations of PCP in air and settled dust in houses with the use of wood preservatives containing PCP and the PCP blood and urine levels of the occupants of the houses were investigated. Forty-six occupants in 30 buildings were involved in this study.Houses with supposed use of wood preservatives based on earlier results were chosen. In each house samples from 1–3 rooms were investigated. The selection of the rooms depended on the time period used by the occupants (bedroom, living room, oYce, etc.). However, some of the rooms did not contain treated wood parts. A total of 75 rooms were involved in this study.Beginning in May 1996, sampling of air dust was repeated four times in each house within 18 months. Prior to each sampling the occupants were asked to stop active ventilation of the rooms at least 12 h before sampling, and not to clean the floor 2 d before sampling. The rooms were used in the usual way during sampling, except for keeping the windows closed. Two parallel air samples were taken in each room.Sampling took place in two impingers in series with 75 ml of 0.1M K2CO3 solution each. The air flow rate was 2 1 min-1. The sampling duration was 5 h, so a total volume of 600 1 was sampled. Temperature, relative humidity, and atmospheric pressure were measured and recorded in each room during sampling. Dust samples were taken instantly after air sampling by vacuuming 1–2 m2 of flooring. The filters used (70 mm round Fig. 1 PCP concentrations in air. Results of the four times repeated paper filters, Schleicher & Schu� ll ) were positioned in a special measurements. filter holder (Alk, Denmark) direct at the opening of the vacuum cleaner tube to avoid contamination. In dust sampling, special care was taken to sample only fresh dust.‘‘Old dust’’ normally exhibits higher loads of PCP, so sampling old dust could cause unusually high values in the samples. Special care was paid to avoid dust sampling from PCP-treated materials. Nevertheless, in one case a PCP-treated carpet was vacuumed, leading to extremely high PCP values in the dust. The data for this sample were excluded from further consideration.Air and dust samples were analysed with dual column GC-ECD after acetylation with acetic anhydride.18 Results and discussion Thirty-six of the 75 rooms investigated were reconstructed within the period of our study. Therefore, we had 39 rooms with an unchanged contamination status during the measurement campaign. The following discussion of the variability of the PCP concentrations isthe measurements in these unchanged rooms.The PCP concentrations in air in these rooms were in the range from <0.3 to 236.9 ng m-3 (mean 11.8 ng m-3) and those in dust from 83 mg kg-1 to 12.5 mg kg-1 (mean 1.4 mg kg-1). In order to establish whether the variance of the four repeated measurements exceeds the variance of the parallel samples in the first step, the pooled standard deviation was calculated from the results for the duplicate samples and the method repeatability was estimated.A relative standard deviation (RSD) of 25% was calculated for the air analysis method. The four times repeated measurements of PCP concentrations Fig. 2 PCP concentrations in dust. Results of the four times repeated in air and dust showed a high variation of the measured values measurements.(Fig. 1 and 2). The variation of the results is to a large extent in the same range as the average concentrations determined. In the air analysis we found RSDs of the four times repeated exhibited reproducible results only in some rooms with very low PCP concentrations in air, where no PCP source could be measurements in the range 12.7–164% (mean 65.4%).In order to check the repeatability of the air measurements a variance identified. In 30 cases the variance of the repeated measurements exceeded the variance of the parallel measurements. ratio test (F-test) was performed. In this test the RSDs of the four times repeated measurements were compared with those This result reflects the high variability of indoor air concentrations of PCP.It is known that PCP concentrations in calculated from the parallel samples. The F-test ( p = 95%) 354 J. Environ. Monit., 1999, 1, 353–356indoor air depend on room ventilation, humidity, and tempera- ments only together with information on the situation in the building. When there is any doubt about the contamination ture (source strength). Therefore, air analyses can only measure the momentary concentration.status, determination of the PCP concentration in air is indicated. In the German ‘‘PCP Guideline’’ these measure- The repeated measurements of the PCP concentration in dust showed similar results for the variability. The RSD ranged ments are the next step in the investigation of possible danger to the inhabitants or users of a building. Exceeding the limit between 8.4 and 127.5% (mean 41.7%).As only a single sample was taken from each sampling, no formal test for the repeat- of 100 ng m-3 indicates the need for further measurements (human monitoring). ability could be performed. The high variability of the dust data reflects the high heterogeneity of the matrix dust. The Regarding the variation of the PCP concentration in air, care is reasonable.An underestimation of the contamination degree of adsorption of PCP on dust depends on the composition, shape, and size of the particles. It also depends on the status is possible. The investigation of our results from four times repeated parallel sampling unequivocally shows this time for which the particles are exposed to the PCP in the air.Older dust samples normally exhibit higher PCP loads than possibility. From the examples in Fig. 5 it can be seen that in some cases a single measurement of the PCP concentration in fresh dust. At present, unfortunately, there is no suitable method to determine the age of the dust sampled. air is not valid for a decision as to whether to undertake an investigation of the blood of the inhabitants or not. For this Our suspicion that the value of the RSD of the results of the repeated measurements is correlated inversely with the decision data from dust measurements and from the possibly treated wood are also necessary.If in doubt, human monitoring average concentrations was refuted by the data. The dependences of the RSDs from the measured PCP concentrations is indicated.Air sampling is also used for monitoring the success of the are plotted in Fig. 3 and 4. The relative variance of the PCP concentrations in air and dust found in the four times repeated reconstruction of a contaminated building. The data from the 36 rooms which were reconstructed within our study again measurements in the diVerent rooms does not depend on the value of the average concentration in the individual room.exhibit a scattered picture (Fig. 6). In some cases a reduction of the PCP concentrations in air is observed and in some cases The question of whether there is a way to discover the ‘‘real contamination’’ of a room will be discussed on the basis of not. In all cases where the reduction is not very distinct, a thorough examination of the executed reconstruction is neces- the German ‘‘PCP Guideline’’.In this guideline the measurement of PCP concentrations of freshly settled dust is prescribed sary. Special attention should be paid to contaminated objects as secondary sources. as a first step in measuring the contamination of a room or building. If a PCP concentration in dust of 1 mg kg-1 is The results of our study clearly show that single data on PCP concentrations in air or dust should be handled very exceeded, the measurement of the PCP concentration in air is indicated.Our study had shown that the measurement of PCP carefully. In many cases the decision for room or building reconstruction can only be made by taking a set of data concentrations in dust can lead to a false estimation of the room contamination status.The high variability of the matrix including human monitoring into account. of the settled dust and the diYculties in taking representative samples led to results which are useful for screening analyses, but not for a decision about the extent of contamination. Therefore, we recommend the use of results from dust measure- Fig. 5 PCP concentrations in air.Examples of parallel samples in the four times repeated measurements. Rooms with unchanged contamination status during the study. Fig. 3 RSD of the PCP concentration in air versus the average PCP concentration in the four times repeated measurements. Fig. 6 PCP concentrations in air. Examples of parallel samples in the Fig. 4 RSD of the PCP concentration in dust versus the average PCP four times repeated measurements.Rooms with reconstruction during the study. concentration in the four times repeated measurements. J. Environ. 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