single-time assays of trihalomethanes in drinking water. Furthermore, there is sufficient variation in even a large system so that a simple harmonic model cannot allow prediction of trihalomethane concentrations from one day t o t h e next. If a maximum contaminant level for these compounds in drinking water is to be monitored, recognition of the 24-h variation is essential, but in addition the larger contribution of as yet undefined sources of day-to-day variability must be taken into account. T h e observed day-to-day variability may be of a systematic nature, Le., possibly reflecting certain weekly cycles in water usage or in operations of the water treatment plant. Or, it may be simply a part of the broad scale irregular fluctuations known t o be typical for the day-to-day behavior of river flow, ambient air and water temperatures, influencing the amount of humic material available for reaction with chlorine and the rate of trihalomethane formation. This question, although it cannot be answered with certainty given the available data, is, however, important, since it has a bearing on the potential predictability of trihalomethane concentrations in drinking water. An investigation is contemplated to address this matter.
( 3 ) “Standard Methods for Examination of Water and Wastewater”, 12th ed., American Public Health Association, Washington, D.C., 1976, p 93. (4) Blackman, R.B., Tukey, J. \V,,“ T h e Measurement of Power Spectra from the Point of View of Communication Engineering”, Dover Publications, New York, 1959. (5) .Jenkins, G. M., Lt’atts, D. G., “Spectral Analysis and Its Applications”, Holden-Day, San Francisco, 1969. (6) Tukey, J. W., in Symposium on Applications of Auto-Correlation Analysis to Physical Problems, Office of Naval Research, FVoods Hole, Mass., 1959. ( 7 ) Box, G. E. P., Jenkins, G. M., “Time Series Analysis Forecasting and Control”, Holden-Day, San Francisco, 1970. (8)Bliss, C. 1.: Conn. Agric. E x p . S t n . ,veu Hai’en Bull., No. 615 (1958). (9) Cech, I., Ph.D. Dissertation, T h e University of Texas Health Science Center, Houston, Tex., 1973. (10) Smith, V. L., Cech, I., Bogdan, G., Brown, J., manuscript in preparation. (11) Rook, J. J., Enuiron. Sei. Techno/., 11,478 (1977). (12) Deinzer, M., Schamburg, F., Kleing, E., Ent>iron.Health Persp., 24, 209 (1978). (13) Laxen, D. P. H., Harrison, R. M., W a t e r Res., 11, l ( l 9 7 7 ) . (14) Stevens, A. A,, Slocum, C. J., Seeger, D. R., Robeck, G. G., “The Environmental Impact of Water Chlorination”, Oak Ridge National Laboratory, Oak Ridge, Tenn., 1976.
Literature Cited (1) Fed Regzst , 43 (No. 28) (Feb 9, 1978). ( 2 ) Keith, “Identification and Analysis of Organic Pollutants in Water”, Ann Arbor Science Publishers, Ann Arbor, Mich., 1976, p 105.
Receiced f o r rerieu, May 8 , 1979. Accepted Noisember 9, 1979. T h i s incestigation was supported in part by Grant X o , 1 ROl CA24138-01, aii,arded by t h e National Cancer Institute, D H E W , t o Irina Cech, Ph.D. (principal inuestigator).
Photolysis of Pentachlorophenol-Treated Wood. Chlorinated Dibenzo-p-dioxin Formation Lester L. Lamparski” and Rudolph H. Stehl Analytical Laboratories, Dow Chemical U.S.A., Midland, Mich. 48640
Robert L. Johnson Designed Products Department, Dow Chemical U.S.A., Midland, Mich. 48640
Laboratory studies have been conducted to determine the effect of sunlight on the concentrations of pentachlorophenol ( P C P ) and chlorinated dibenzo-p-dioxins (CDDs) in wood treated with PCP. Wood samples were treated with technical P C P , Dowicide EC-7 antimicrobial, and purified PCP. Irradiation experiments were designed using either artificial sunlamps or natural sunlight. P C P determinations were made by flame ionization gas chromatography, and dioxin determinations were made by electron-capture gas chromatography and gas chromatography-mass spectrometry. Photolytic condensation of P C P to form octachlorodibenzo-p-dioxin (OCDD) was observed on a wood substrate. This effect was greatly reduced by the addition of a hydrocarbon oil (example: P - 9 oil). OCDD concentrations in photolyzed wood samples ranged from 4 pg/g of P C P for Dowicide EC-7 and purified P C P to -1500 pg/g of technical P C P when both were stabilized with hydrocarbon oil. Data on the distribution of CDDs as a function of depth are also presented. Pentachlorophenol (PCP),which is commonly used as a wood preservative, can contain chlorinated dibenzo-p-dioxins (CDDs) as impurities ( I ) .Technical P C P has been reported t o contain chlorodiphenyl ethers, chlorodibenzo-p-dioxins, 196
Environmental Science & Technology
chlorodibenzofurans, and hydroxychlorodiphenyl ethers; the octachlorodibenzo-p-dioxin (OCDD) content of technical P C P is typically 500-1500 ppm (2). Purified P C P Dowicide EC-7 (trademark of T h e Dow Chemical Co.) contains much lower levels of these impurities. Specification levels of hexachlorodibenzo-p-dioxins (HxCDD) and OCDD are 1 and 30 ppm, respectively ( 1 ) . Although a wide variety of CDDs have been reported in the environment (3-5) from a variety of both natural and synthetic sources, little information exists to allow identification of the routes for occurrence of these compounds in the environment. Thermal stresses, both combustive and pyrolytic, have been reported to produce CDDs. T h e photolytic condensation of chlorophenols has been widely studied. Irradiation of aqueous solutions of 2,4-dichlorophenol and 2,4,5-trichlorophenol gave little reaction unless a sensitizer such as riboflavin was present. Reaction products were chlorophenoxyphenols and chlorodihydroxybiphenyls (6). In these studies CDDs could not be detected in the reaction products by electron-capture gas chromatography (EC-GC). In alkaline aqueous solutions, however, the condensation of P C P to form OCDD proceeds quite readily ( 7 , R ) . Also, photolysis of OCDD has been shown to yield a variety of CDDs of decreasing chlorine content (9-1 1). Recently, because of concern over the formation of CDDs
0013-936X/80/0914-0196$01.00/0
@ 1980 American Chemical Society
Photolysis Conditions. Photolysis experiments were conducted under a General Electric Model RS sunlamp. Wood PCP, tetra, a HXCDD, OCDD, samples were placed in Pyrex petri dish bottoms (150X 10 source % % pprn HxCDD pprn m m ) and were covered with 1/8-in.thick quartz plates. A new composited technical 88.5 5.0 14 1100 lamp was used for each experiment to provide nearly constant Dowicide EC-7 92.7 7.5 0.3 3 irradiation conditions. Samples were placed a distance of 1 Aldrich (purified) (99.5) 0.5 n.d. n.d. n.d. m from the source. A single experiment using natural sunlight (outdoors) was conducted to determine if the laboratory model a Tetrachlorophenols present may include several isomers. Value reported is the sum of all isomers. n.d. indicates not detected with a limit of detection simulated natural conditions. In each experiment individual of approximately 25 ppb. pieces of exposed wood were removed for analysis after specified periods of time. Measured light intensities for a General Electric RS sunon the surface of PCP-treated wood upon exposure to sunlight, lamp have been reported (13). Intensities of Midland sunlight a series of analytical studies has been undertaken. T h e purhave also been reported by the same authors. pose of these studies was to determine t h e amount, under Sample Extraction and Purification. Wood samples (1 simulated natural conditions, of CDDs formed and the effects g) were sliced into thin (-1 m m X 5 cm) pieces, which were o f several parameters on the rate and amount of such reacthen ground into a fine sawdust with Tekmar Tissuemizer in tions. 50 mL of a solvent of benzene-methanol-acetic acid (45:45:10, by volume). Mixtures were allowed to stand overnight and Experimental then filtered. Filtrates were acidified with 2 mL of concenReagents. Wood samples were pressure-treated with trated HC1, and 100 mL of distilled water was added. T h e pentachlorophenol from various sources: (1) composite of mixture was shaken and the benzene layer removed; the technical P C P from various manufacturers; (2) typical lot of aqueous phase was reextracted twice with 10 mL of benzene. Dowicide EC-7; (3) Gold Label pentachlorophenol from AlT h e benzene extracts were combined and the aqueous phase drich Chemical Co. T h e Aldrich P C P was purified before use discarded. The benzene solution was extracted with 3 X 10 mL by recrystallization and adsorption liquid chromatography portions of 0.5 N aqueous NaOH to remove PCP. The benzene on activated carbon and silica gel. 2,3,4,6-Tetrachlorophenol phase was evaporated to dryness under a stream of nitrogen concentration was 0.5% and HxCDD, heptachlorodibenzoand reserved for further purification and analysis. The caustic p-dioxin (HpCDD), and OCDD concentrations were all 25 ppb extract was acidified with 2 mL of concentrated HCI and exor less. Table I summarizes the composition of materials used tracted with 2 X 25 mL of methylene chloride. The methylene in this work. P C P carriers for wood impregnation were either chloride extracts were combined for GC determination of P - 9 hydrocarbon oil or methylene chloride. PCP. Wood Treatment Procedure. T h e wood used for these T h e benzene residue was dissolved in 30 mL of hexane and experiments was '/*-in. rotary cut Southern Yellow Pine vewas purified by passage through a 0.9-cm (i.d.1 column conneer. T h e wood samples, 5 replicate 6 in. x 12 in. pieces, for taining 4.0 g of a packing composed of 80/100 mesh silica gel each treatment. were contained in a stainless steel container with 44m~by weight concentrated H ~ S O J T . h e eluant was and enclosed in a sealed pressure vessel. collected on a 21.0 cm X 0.6 cm (i.d.) column containing 5.0 T h e treating cycle for each preservative solvent system g of Bio-Rad AG-10 basic alumina. T h e column was washed consisted of t h e following operational sequence: (1) veneer with 50 mL of'50'% (v/v) CCL-hexane, and the CDD fraction samples exposed to a 28-in. Hg vacuum for 30 min; (2) vacuum eluted with 20 mL of 50% (v/v) CH&I?-hexane. T h e CDD reduced to 20 in. by introducing the treatment solvent; (3) fraction was evaporated under a stream of' nitrogen and the solvent vented off and treatment solution added; (4) vacuum residue dissolved in isooctane for analysis by EC-GC. released and wood veneer samples soaked in treatment soluGas Chromatographic Conditions. Gas chromatographic tion for 30 min; ( 5 ) samples removed from solution, placed in analyses were performed on a Varian Model 3700 equipped 42 "C oven for 12 h; (6) samples cut into -2 in. X 2 in. squares, with flame ionization and electron-capture detectors. For P C P individually wrapped first in aluminum foil and then in Saran determinations, the flame ionization detector was used. A 150 Wrap plastic film; ( 7 ) all wrapped 2 in. X 2 in. wood samples cm X 2 mm (i.d.1 glass column packed with diethylene glycol for each treatment placed in polyethylene bags and stored in succinate bonded onto 80/100 mesh Chromosorb V \ was used a refrigerator until needed. to elute the PCP without derivatization. This column techPrior to treatment, the 6 in. X 12 in. wood samples were nology is a recent development of T h e Dow Chemical Co. A room conditioned for 48 h and weighed. As soon as possible description of this bonded-column technique will be described after the treatment, the samples were weighed again so that separately. Chromatograph temperatures were: column, 150 the percent treating solution retention and calculated percent "C; injection port, 160 "C; detector, 300 "C. pentachlorophenol retention could be derived. CDDs were determined by EC-GC on a 180 cm X 2 m m A review of Dow service records showed retentions of pen( i d . ) glass column packed with 0.6% poly(MPE) coated over tachlorophenol as high as 1.6 Ib/ft' above ground and 1.2 lb/ft a support of' specially deactivated SO/lOO mesh Chromosorb below ground in the outer '/in. l of Southern Yellow pine wood W. T h e chromatograph temperatures were: column, pro( I); this would calculate out to 4.8% pentachlorophenol. grammed from 260 to 290 "C a t 5 "C/min: injection port, 300 Therefore, a 5% treating solution at 100% pickup should result "C; detector, 340 "C. Confirmation of peak identity was acin a veneer treatment in the same general range as maximum complished on a H P 5992 gas chromatograph-mass specSouthern Yellow Pine pole retentions a t the outer l/x-l/J in. trometer (GC-MS) operated in the selected-ion-monitoring In all treatment instances in which methylene chloride was mode. utilized, the percent treating solution retention averaged Depth Profile. Determinations of CDDs concentrations 113.9. T h e pentachlorophenol content, based on 5.0 wt c~soas a function of distance from the surface of t h e wood were lutions, calculated to average 5.7%. made by microtoming 25-pm slices from the surface of'the T h e retentions for both solution and pentachlorophenol wood sample that had been exposed to artificial sunlight for were somewhat lower when the P-9 oil was used as the im21 days. Consecutive pairs of 25-pm slices were combined to pregnation solvent; the calculated retention was 83.5% and provide sufficient samples for the subsequent cleanup, P C P , t h e resulting P C P content was 4.2%. and CDDs analyses. Table 1. Composition of PCP Used for Treatment
Volume 14, Number 2, February 1980
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Figure 1. PCP photolysis: OCDD content vs. exposure time to natural and artificial sunlight: (A) Aldrich purified PCP-CH2C12, sunlamp; (B) Dowicide EC-7-CH2C12, sunlamp: (C) Dowicide EC-7-CH2CI2, sunlight
Results and Discussion Extraction Efficiency. T h e difficulty in quantitatively removing pentachlorophenol from a wood matrix has been reported by Zicherman ( 1 4 ) . Using scanning electron microscopy-energy-dispersive X-ray analysis (SEM-EDXA), he observed benzene was not capable of extracting P C P deposited within cell walls by pressure treatment. Approximately 25% of P C P was not extracted by benzene. Williams (15)has observed that a solution of methanol-acetic acid (9:1, by volume) was effective in extracting P C P from wood. No determination of P C P residue remaining after extraction was presented. T o determine the efficiency of extraction with methanolacetic acid, successive extractions of a single sample showed that the second extract contained only 1.3% of the amount of P C P found in the first extract. Subsequent analysis of the wood matrix for total chlorine content by neutron activation analysis indicated that no more than 0.54%of the P C P remained in the wood after two extractions with methanolacetic acid. Methanol-acetic acid, however, was not as effective as a benzene-ethanol ( l : l , by volume) solvent for the extraction of the CDDs from a treated wood matrix. T h e combination of these two extractants to benzeneemethanolacetic acid in a ratio of 4 5 4 5 1 0 gave good extraction of both types of compounds. This solvent system is similar to one reported by Leutritz ( 2 6 ) (an azeotropic mixture of toluene, ethanol, and acetic acid) for the Soxhlet extraction of P C P from wood. Analyses of treated wood samples before exposure showed wide variations in both P C P and CDDs concentrations. On a single 50 X 50 m m piece of wood, variations in P C P concentrations from 3.6 to 5.3% were observed in 5-mm slices, 198
Environmental Science & Technology
0.1
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Days Exposure
Figure 2. PCP photolysis: HxCDD content vs. exposure time to natural and artificial sunlight: (A) Aldrich purified PCP-CH2CI2, sunlamp: (B) Dowicide EC-7-CH2C12, sunlamp; (C) Dowicide EC-7-CH2CI2, sunlight
apparently due to nonhomogeneity of the wood matrix to accept pressure impregnation. T h e OCDD content showed a parallel variation. When the OCDD content was normalized to the P C P content, an average concentration of seven determinations was 2.80 ng of OCDD/mg of P C P (u = 0.07 ng/mg, 2.5% relative). This agreed very well with an independent determination of 3.0 ppm of OCDD that was present in the EC-7 used to treat the wood. All subsequent results are reported normalized to the actual P C P content of the sample. Photolysis Experiments. T h e initial photolysis experiments were designed to determine if, under usual treatment and exposure conditions, CDDs would be formed by exposure to sunlight. Samples of Southern Yellow Pine were treated a t 0.028 g/cm’ (1.75 lb/ft’) with Dowicide EC-7 and Aldrich P C P (purified) using methylene chloride as the carrier. Light sources were both natural and artificial sunlight. The results of these three experiments are shown in Figure 1.An increase in OCDD concentration was clearly observed, while treated controls stored in the dark showed constant concentrations. After approximately 20 days, the OCDD concentration reached a plateau of about 70 ppm (ng of OCDD/mg of P C P ) for the two artificial sunlight exposures. T h e natural sunlight exposure shows an apparent decrease in OCDD concentration after about 20 days. Two important conclusions to be drawn from this experiment are: (1) the GE Model RS sunlamp provides a reasonable approximation to the natural sunlight found in Midland, Mich. (43’37.1”, 84’13.9’W) in the month of August; ( 2 ) EC-‘7 shows the same reaction characteristics as very pure PCP. HxCDD and HpCDD concentrations were also determined in the same set of exposures. T h e HxCDD data are shown in Figure 2. T h e HpCDD data are similar to the curves shown
10,000
Table II. Summary of Photolysis of Penta-Treated Wood penta type
1000
treating solution
bulk dioxin concn, ppm a FlxCDD OCDD
purified
CH&lp
19
Dowicide EC-7 purified Dowicide EC-7 technical
CH,CI* oil oil oil
15 b
b C
f8 f8 2.2 f 0.6 4.4 f 0.5 1620 f 130 76
64
Concentrations are reported based on PCP content and are the maximum concentrations observed. These concentrations were too low (less than 1 ppm) to be determined, although they were detected. The determination of HxCDD in technical PCP before and after irradiation is not accurate by EC-GC. The chromatographic peak at the retention time of HxCDD was shown not to be HxCDD by GC-MS. a
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Figure 3. PCP photolysis: OCDD content vs. exposure time: (A) pure PCP-P-9 oil, sunlamp; (B) EC-7-P9 oil, sunlamp; (C) tech PCP-P-9 oil, sunlamp
for HxCDD and OCDD. T h e equilibrium concentrations of HpCDD were: pure PCP-CHaCl?, 17 ppm; EC-7-CHaC12,35 ppm; EC-7-CH2C1z sunlight, 35 ppm. T h e distribution of the HpCDD isomers from the photolysis of these samples yields some interesting conclusions. Buser (7) has reported that the major HpCDD isomer derived from the UV photolysis of OCDD is 1,2,3,4,6,7,9-HpCDD.We have observed, however, t h a t in all cases this was the minor isomer. This isomer accounted for only 30% of the total HpCDD content in the photolyzed EC-7 samples and 13% in the photolyzed pure P C P sample. Wt: observed even greater predominance of the 1,2,3,4,6,7&HpCDD isomer in the photolyzed pure P C P , which contained only a small amount (0.5T0) of tetrachlorophenol. These results suggest that: Most of the HxCDD and HpCDD is formed by photolytic degradation of OCDD rather than by condensation of T C P and P C P . OCDD pres,ent on a wood surface is somehow activated so that the preferential chlorine loss occurs at the peri position rather than the lateral position that Buser observed in solution. A second series of experiments involving pure P C P , EC-7, and technical P C P was conducted using a hydrocarbon oil ( P - 9 oil) as the solvent for P C P . These samples were photolyzed under artificial sunlight as previously described. A portion of the data for OCDD is shown in Figure 3. The OCDD content of the technical PCP-P-9 oil treated showed no a p parent change in concentration upon exposure to sunlight (Figure 3 ) . Thirteen samples were analyzed over a 64-day period. T h e average OCDD concentration observed was 1540 ppm with a standard deviation of 150 ppm. As can be seen by comparing the plateau values in Figures 1 and 3 and summarized in Table 11, significantly less OCDD is formed when
P - 9 oil is present as the solvent for P C P , which contains little dioxin before impregnation. While TCDD was not detected as a result of this photolysis, recent work in our laboratories has shown that the photolytic interconversions of CCDs are extremely isomer dependent, with TCDD degradation being faster than the photolytic formation from higher CDDs. This work will be reported in a future publication (17). T h e data shown result from the sum of a t least two reactions, the condensation of P C P to form OCDD and the photolytic decomposition of OCDD. Apparently, the lower OCDD levels are due to decreased formation rather than increased degradation of OCDD because the technical P C P treated with P - 9 oil showed ’no decrease in CDDs content (Figure 3). HpCDD showed similarly lower concentrations with P-9 oil relative to the methylene chloride treatment. For both types of purified P C P , HxCDD and HpCDD concentrations remained below 1 ppm when P - 9 oil was used. T h e determination of HxCDD in technical P C P was found to be inaccurate by EC-GC, either before or after irradiation. When these solutions were examined by GC-MS, a component tentatively identified as decachlorodiphenyl ether was observed a t the HxCDD retention time. Although this component was observed to increase very quickly on irradiation, no quantitation was made. Depth Profile Studies. Because of t h e photolytic condensation of P C P to form OCDD, it would be reasonable to assume that the greatest concentration of CDDs would be expected on the very surface of the exposed wood. Since previous experiments had all involved analysis of the whole 3-mm thick piece of wood, any photolytic effects were “averaged” over this thickness. In order to better characterize the distribution of the CDDs in photolyzed wood samples, a series of depth profile experiments was conducted. T h e results of depth profile analyses on samples of P C P treated wood are shown in Figure 4 with OCDD concentration expressed as a function of depth. Samples were exposed to artificial sunlight for 21 days prior to microtoming. Samples were treated with pure P C P with methylene chloride carrier and technical P C P and EC-7 each with P - 9 oil as the carrier. Decreased OCDD concentration a t the surface of the technical PCP-treated sample indicates that the P - 9 oil may increase the rate of OCDD degradation slightly. Although the concentration of OCDD from Dowicide EC-7 is slightly higher a t the surface (for P-9 oil impregnated samples), the surface concentrations are far less than those observed with purified P C P when methylene chloride is used as t h e impregnation solvent. This also suggests that P - 9 may either reduce condensation of P C P to OCDD or accelerate degradation to other species b y providing a hydrocarbon trap for free-radical species ( 6 ) .Distributions of HxCDD and HpCDD were similar Volume 14, Number 2, February 1980
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concentrations of OCDD (and HxCDD) if the initial concentrations of CDDs in P C P are reduced (compare Figure 3, A, B, and C) to less than 1%of the amounts present with current technical PCP. Previous work has already demonstrated the efficiency of Dowicide EC-7 (18) for its intended biological activity toward bacteria. While the relative environmental burdens of CDDs due to individual identified sources will probably never be established (19),this work clearly demonstrates the CDD reduction that can be achieved by both control of the dioxin content of the P C P and the treatment method. Acknowledgment
L
The authors wish to thank W. B. Crummett, J. D. DeVrieze, and W. L. Dilling for helpful discussions during this work, H. K. Goersch for help in making spectral measurements, and T. J. Nestrick and C. W. Kocher for purification of the PCP. T h e preparation and treatment of the wood samples by R. M. Gooch and J. R. Conklin are greatly appreciated.
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Literature Cited
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to OCDD in the technical PCP-treated sample. No quantitation of HxCDD and HpCDD was attempted for the EC-7 samples because the concentrations were too low t o be accurately determined.
Conclusion T h e photolysis experiments described in this study were designed to simulate natural conditions of light intensity and wavelength distribution. T h e analytical results indicate t h a t the photolytic reactions a t the surface of Dowicide EC-7 treated wood with methylene chloride solvent can produce CDDs at concentrations that approach those in technical PCP. If a hydrocarbon oil, such as P-9, is used as a carrier, the OCDD concentration on the wood surface is only about 1%of the amount in typical technical PCP. While this work clearly demonstrates the formation of CDDs from P C P in a solid (wood) matrix, especially in the absence of hydrocarbon solvents, it also shows t h a t the photolytic mechanisms can result in dramatically reduced surface
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(1) Pfeiffer, C. D., Nestrick, T. J., Kocher, C. W., Anal. Chem., 50, 800 (1978). ( 2 ) Mieure, J . P., Hicks, O., Kaley, R. G., Michael, P. R., J . Chromatopr. Sci., 15, 275 (1977). ( 3 ) Dow Chemical Co., “The Trace Chemistries of Fire”, Midland, Mich., Nov 1978. (4) Olie, K., Vermeulen, P. L., Hutzinger, O., Chemosphere, 6,455 (1977). (5) Buser, H. R., Bosshardt, H. P., Rappe, C.. Chemosphere, 7, 165 (1978). ( 6 ) Plimmer, J . R., Klingehiel, U. I., Science, 174,407 (1971). (7) Stehl, R. H., Papenfuss, R. R., Hredeweg, R. A,, Roberts, R. W., Adu. Chem. Ser., No. 120, 119 (1973). (8) Crosby, D. G., Wong, A. S., paper presented at the 160th National Meeting of the American Chemical Society, Chicago, Sept 17, 1970. (9) Croshy, D. G., Wong, A. S., Plimmer, J . R., Woolson, E. A,, Science, 173, 748 (1971). (10) Buser, H. R., J . Chromatogr., 129, :303 (1976). (11) Crosby, D. G., Moilanen, K. W., Wong, A. S.,Enuiron. Health Perspect., 5 , 259 (1973). (12) Huber, H. A.,Olson, G. E., “Service Records and Analyses of 120 Southern Yellow Pine Poles Commercially Treated with Pentachlorophenol”, presented to the Transmission and Distribution Committee o f t h e Edison Electric Institute, New York, T h e DCJW Chemical Co., Midland, Mich., 1958. (13) Kallos, G. $J., Tou, J . C., EnL’iron. Sci. Techno/., 11, 1101 ( 197 1). (14) Zicherman, d. B., Wood piher, 7 (21, 110 (1975). (15) Williams, A. R., Analyst ( L o n d o n ) , 96, 296 (1971). (16) Leutritz, J . , /‘roc. A m . Wood-PreherL’.Assoc., 67, 198 (1971). (17) Nestrick, T. J . , Lamparski, 1,. L., manuscript in preparation. (18) Johnson, R. L., Gehring, P. J . , Kociha, R. J., Schwetz, R. A,, Enuiron. Health I’erspect., 5, 171 (1973). (19) Townsend, D. I., paper presented at the 178th National Meeting of the American Chemical Society, Washington, D.C., Sept 13, 1979.
Krceiued /or reuieu. M a y 1 1 , 1979. Accepted Nouember 14, 1979
