Environ. Sci. Techno/. 1995, 29, 677-684
Polychlorinated Dibenzo-p-dioxin and Dibenzohran Contamination at Metal Recovery Facilities, Open Burn Sites,-and a Railroad Car Incineration Facility MARTHA H A R N L Y , * ROBERT S T E P H E N S , + CHARLES M C L A U G H L I N , * J E R R Y MARCOTTE,’ MYRTO P E T R E A S , + A N D L Y N N GOLDMANS Environmental Health Investigations Branch, California Department of Health Services (DHS), Berkeley, California 94704
Soil and ash surface samples ( n = 44) were collected from three historical metal recovery facilities where copper scrap was a dominant feed stream, three sites of open burning where evidence of copper recovery was visible, and from a railroad car incineration facility. Concentrations of polychlorinated dibenzo-pdioxins (PCDD) and dibenzofurans (PCDF) are in the l o w parts per billion range with PCDF concentrations significantly lower in samples from the railroad car facility. In fly ash from a copper wire and aluminum scrap recovery facility, PCDD and PCDF concentrations are high, 50 and 460 ppm. Consistent with that cited for other combustion sources, ratios of PCDF to PCDD are mostly greater than 1. However, a lower ratio (0.4), is observed in samples from the railroad car incineration facility. OCDF and OCDD are significantly correlated with 2,3,7,8-TCDD toxicity equivalents (TEQ). These congeners may be inexpensively analyzed and may be useful as indicator chemicals at similar sites and facilities. Further investigations of metal recovery facilities and open burn sites worldwide are necessary.
Introduction Polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) emissions from the incineration of industrial, municipal, and chemical wastes have been the focus of considerable study (1). Recent evidence of human carcinogenicity of the most potent of these compounds, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (2)will likely quicken the investigative pace. One focus of research has been PCDDlPCDF emissions fromthe buming of chemicals and materials contaminated with PCDDsl PCDFs, e.g., pentachlorophenol (PCP) and wood treated with PCP including utility poles (3,4). Very high levels of PCDFs have also been detected in soot from the incineration of particular chemicals, most notably transformer oil contaminated with polychlorinated biphenyls (PCBs) (5). Other factors, however, may increase PCDDlPCDF emissions. These factors include the incineration of polyvinyl chloride (PVC) (6, 7), a low temperature (300-450 “C) dependent catalytic effect of copper and perhaps other metals (81, and an oxygen “surplus” environment (9). These findings led to investigations of PCDDlPCDF emissions from metal recovery furnaces and sites of open burning where metal scrap-including copper wire, which is frequently covered with PVC-is burned or smelted to recover copper (10-15). PCDDlPCDF emissions from accidental fires of electrical wiring have also been investigated (7). Stack emissions from metal recovery furnaces are of particular concern: copper smelting generates much particulate matter in the exit gas stream;the recommended air pollution control equipment (baghouses and afterbumers) operate at 90-99% effectiveness; and the exit gas streams are cooled prior to entry into baghouses, allowing for an appreciable residence time at low temperature (16). PCDDlPCDF stack emissions at metal recovery facilities, however, have rarely been tested. Atmospheric emissions from metal recovery facilities may also be generated by resuspension from ash piles on the premises. These piles may contain both “fly ash” (ash removed from stack air pollution control equipment) and “bottom ash” (ash remaining after incineration has been completed or after an open burn.) Fly ash generally contains higher levels of PCDDlPCDF than bottom ash (9). PCDDl PCDF concentrations in fly ash and bottom ash samples from facilities in the United States have occasionally been reported (11, 12). These studies have not included measurements of the 2,3,7,8-substituted PCDD and PCDF, which are necessary to calculate 2,3,7,8-TCDDequivalents (TEQs),the commonly reported toxicologically weighted (relativeto 2,3,7,8-TCDD)sum of 2,3,7,8-substitutedPCDDl PCDF congeners (I 7 ) . The California Department of Health Services (CDHS) investigated historical open burning locations and several copper wirelscrap metal recovery facilities in and near a * Corresponding author; e-mail address:
[email protected]. gov. + Hazardous Materials Laboratory, currently part of the California Environmental Protection Agency. Toxic Substances Control Program, currently part of the Califomia Environmental Protection Agency. 5 Currently with the U.S. Environmental Protection Agency.
*
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VOL. 29, NO. 3,1995 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
677
TABLE 1
Description of Open Burn Sites and Metal Recovery Facilities code
distance from town
dates of operation
A
2 m i south
ceased 1970's
B C
2 m i west 0.25 m i east
unknown unknown
Open Burn Sites incinerated materials in on-site ash piles at initial inspection (1988) copper wire electronic parts automobile parts paint containers copper scrap copper wire electronic parts
community reported historically burned materials copper wire car seats tires household trash copper wire copper wire
Metal Recovery Facilities distance from town
dates of operation
D
9.0 m i north
1969- 1990
E
9.8 m i north
1970- 1991
F
10.5 m i north
1973- 1989
G
11.0 m i north
1960- 1989
code
incinerated material copper scrap transformer coils aluminum parts copper wire electronic parts lead cable copper wire rubber covered oil well flanges wood railroad cars
small desert town. The multitude of ash and soil samples collected during the course of preliminary investigations allowed us to examine the levels and interrelationships of 2,3,7,8-substituted PCDD/PCDF congeners, PCDD/PCDF tetra to octa homologues, and TEQ concentrations. Most studies of PCDD/PCDFcontamination are limited by a small number of samples due to the expense of the laboratory analysis. To explore the feasibility of sample screening techniques, we studied correlations between TEQ concentrations and compounds that can be inexpensively measured, Le., octachlorodibenzo-p-dioxin (OCDD), octachlorodibenzofuran (OCDF) (181, and copper.
Site and Facility Description Facilities and sites in and near a California desert town where metal recovery and open burning operations had occurred were investigated (Table 1). To gather information, inspections were conducted, and local air pollution control agency records were reviewed. Three sites where open burning had occurred were investigated. Open burning ceased at these locations in the early 1970s when county air pollution regulations changed. These sites are geographically separated by several miles and contain piles of ash and debris, including strands of burned wire and electronic parts. Long-time community residents report burning of miscellaneous trash, including copper scrap, at these sites. One site, 2 mi from the town (site A, Table l ) ,was a particularly frequent site of open burning. Residents report indiscriminate burning of their own trash for a nominal fee and the daily arrival of trucks loaded with car seats, tires, and electrical wiring. These trucks would arrive from a nearby major city in an adjacent county whose air pollution regulations did not allow indiscriminate open burning. Local agency records also indicate that planes from the nearby air base had difficultylanding due to the smoke generated by the burning at this site. Approximately 9 mi north of the town, four adjacent incineratiodsmelting facilities operated through 1991 678 1 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 29. NO. 3, 1995
recovered material copper aluminum copper silver lead copper flanges metal frames
baghouse Yes Yes Yes no
(Table 1). One facilitysmelted copper and aluminum scrap in two separate furnaces connected to a long cooling chamber and then a baghouse. The copper originated from electrical wire, transformers, and capacitors, and the aluminum was from airplane frames, automobile engines, and airplane parts. At the second and third metal recovery facilities, copper wire was incinerated, and the furnaces were equipped with baghouses. At the time of the initial CDHS inspection, however, the second facilityhad shifted to silver recovery and the third to incinerating a particular type of metal oil-wellflange to remove rubber on the outside of the flange. Adjacent to the three metal recovery facilities is a fourth facility where the wood portion of railroad cars was burned off the cars in a furnace equipped with an afterburner. On all four facilities, ash piles and ash contamination of soil was evident. Location of ash piles often shifted on these facilities, and ash was occasionally sold to distant buyers for further refining of the metals in the ash. In addition to the frequently used furnaces, open burning was also documented in local agency records and was particularly evident at the railroad car incineration facility.
Methods Sample Collection. Between 1987 and 1990, hazardous waste specialists collected surface samples from ash and soil at the base of bumed debris. Forty-four sampling locations that appeared visually to be most contaminated with ash were selected. Sampleswere collectedwith a handheld trowel. The number of sample locations at each site and facility was dictated by regulatory activities: three, three, and nine locations were sampled at open burn sites A, B, and C (Table 11, respectively; seven, five, and four locations were sampled at metal recovery facilities D, E, and F (Table 1); and 13 locations were sampled at the railroad car incineration facility. In addition, at the copper wire and aluminum smelting facility, employees collected the fly ash, or baghouse ash, into large bags. Samples were subsequently collected from the bags on two separate
TABLE 2
Average Recoveries of 13&Labeled Standards in Samples and Blanks (n = 56) congener 1,2,3,7,8-PeCDD 1,2,3,6,7,8-HxCDD 1,2,3,4,6,7,8-HpCDD OCDD
recovery 79 71 82 76
congener 2,3,7,8-TCDF 2,3,4,7,8-PeCDF 1,2,3,4,7,8-H~CDF 1,2,3,4,6,7,8-HpCDF OCDF
recovery 78 76 73 81 79
occasions, and each sample was analyzed twice. Other than these fly ash samples, it was not possible to distinguish between ash and ash mixed with soil as ash contamination was widely distributed over the sites and facilities. We have therefore characterized all samples, except for the fly ash, as ashlsoil. Laboratory Methods. To determine the tetra (TCDF), penta (PeCDD, PeCDFl, hexa (HxCDD, HxCDF), hepta (HpCDD, HpCDF), and octa (OCDD, OCDF) homologues and the 2,3,7,8-substituted PCDDlPCDF congeners, all samples were prepared according to Hazardous Materials Method 880 (191, which is based on U.S.Environmental Protection Agency SW-846Method 8280 (20). In brief, each sample was spiked with the 2,3,7,8-substituted I3C-labeled internal standards shown on Table 2. Samples were then Soxhlet-extracted with toluene: cleaned up by potassium silicatelsilica gel, basic alumina, and AX21 carbon. All but two samples were analyzed by high-resolution gas chromatographyllow-resolution mass spectrometry (HRGCl LRMS) (Finnigan 4500) in a negative chemical ionization (NCI)mode. The low sensitivity in the tetra-channelunder NCI does not allow measurement of TCDD, and therefore no TCDD measurements are reported. Field duplicates of one location were analyzed by high-resolution gas chromatography/ high-resolution mass spectrometry (HRGC/ HRMS) (Varian 3400, Finnigan MAT 90) operating in the electron impact (EI) mode (50eV)with a 0.8mA emission and a minimum resolution of 7000 amu. Both instruments used a 60-m, 0.25-pm, DB-5 column and a temperature program (220 "C for 2 min, then 5 "C per minute to 260 "C, followed by 1 "C per minute to 300 "C.) Quantitation was based on isotope dilution. Copper was analyzed according to a modification of EPA SW-846 Method 3050. Samples were treated with 1:1HN03 and 30% H202 over a hot plate; digest were cooled, filtered, and made to final volume with deionized water. Analysis was carried out by ICP-AES (Termo JarreLlAsh, CAP-6)accordingto EPA SW-846Method 6010 (21). QNQC. One method blank was analyzed with each batch of samples (two to seven samples per batch). For the first 32 samples, "background" PCDDlPCDF levels in the method blanks were low, ranging from 0.003 to 6.0 pg. These background levels were more than 10 times below any measurement in the samples. For the remaining 12 samples analyzed with and subsequent to the fly ash, background in the blanks increased dramatically, ranging from 3 pg for 1,2,3,7,8-PeCDDto 1500 pg for OCDF. The high background levels followed the pattem of contamination in the fly ash. For three of the 12 samples, PCDDl PCDF concentrations were low and less than 10 times the levels in the method blank. These three samples, however, were retained in the data set to avoid bias from exclusion of low PCDDlPCDF measurements. No background correction was applied to any of the measurements.
One soillash sample and the two fly ash samples were each analyzed twice. For these three samples, the relative percent difference on all congeners was generally acceptable, being less than 50% for 67% of the measurements. However, for one fly ash analysis, PCDDlPCDF concentrations were consistently greater than 100% of the other analyses with the maximum difference 500% for TCDF. The average percent recovery for each 13C-labeled internal standards across all samples and corresponding blanks was consistently between 70 and 82% (Table 2). In general, recoveries ranged between 40 and 120%, the window specified by the methods (19,201. Nevertheless, 1% of the recoveries for all congeners was greater than 120%, and 10% of the recoveries was less than 40%. The vast majority of the lower recoveries occurred on seven samples, where the recoveries for all congeners ranged between 11% and 61%. In all of these seven samples, however, concentrations were high and above the average for the data set, perhaps reflectingloss of internal standards during dilution. These seven samples were not deleted from the data set because eliminating these samples would bias means toward lower averages. No values were corrected for recoveries. TEQ Calculations. To sum PCDDs and PCDFs relative to the toxicity of 2,3,7,8-TCDD,different governments and agencies have assigned different toxicological weights or factors to PCDDslPCDFs congeners (17). CDHS has established factors based on carcinogenicity (221, and this method assigns higher factors to the lower chlorinated PCDFs than any other method (17). These factors were used to calculate California TEQ (CTEQ) concentrations. To compare values to other studies, "ITEQ" concentrations were calculated using factors which are based on a variety of toxicological end points and were established by an international group (17). These factors are only minimally different from those suggested on the basis of a single end point, receptor binding, the event that mediates toxicological response (23). When congener values were not determined or less than the detection limit, these congeners were not entered into TEQ calculations. Statistical Analysis. All samples were divided into four groups based on expected PCDDlPCDF concentration: (1) the fly ash from the copper wire and aluminum smelting facility; (2) samples from the three adjacent metal recovery facilities; (3) samples from the open-burning sites which had not been active for at least 15 years, and (4) samples from the railroad car incineration facility which did not have a copper feed stream but where PCP-treated wood may have been burned. Analytical values were logarithmicallytransformed and tested for normality with the Wstatistic. Geometric mean concentrations for the samples in each of the four groups were calculated. The logarithmically transformed values were compared between the groups of samples using the student's t-test. Pearson correlation coefficients for copper, OCDD, and OCDF with ITEQ and CTEQ were calculated and tested for an association. To determine whether multiple parameters could more accuratelypredict ITEQ or CTEQ, multiple linear regression analysis was used (24).
Results Table 3 displays the geometric means for PCDD/PCDF values and TEQ values in samples from the fly ash, metal recoveryfurnace facilities, open bum sites, and the railroad VOL. 29, NO. 3, 1995 / ENVIRONMENTAL SCIENCE &TECHNOLOGY 1679
TABLE 3
PCDD/F Geometric Means: fly Ash and AsWSoil Samplesa metal recovery facilities ITEQ CTEQ fly ash (pg/g) factor factor ( n = 2) 2,3,7,8-congeners 1,2,3,7,8-PeCDD 1,2,3,4,7,8-HxCDD 1,2,3,6,7,8-HxCDD 1,2,3,7,8,9-HxCDD 1,2,3,4,6,7,8-HpCDD OCDD 2,3,7,8 -TCDF 1,2,3,7,8-PeCDF 2,3,4,7,8-PeCDF 1,2,3,4,7,8-HxCDF 1,2,3,6,7,8-HxCDF 2,3,4,6,7,8-HxCDF 1,2,3,7,8,9-HxCDF 1,2,3,4,6,7,8-HpCDF 1,2,3,4,7,8,9-HpCDF OCDF CTEQ ITEQ homologues PeCDD HxCDD HpCDD OCDD total PCDD TCDF PeCDF HxCDF HpCDF OCDF total PCDF
0.5 0.1 0.1 0.1 0.01 0.001
1 0.03 0.03 0.03 0.03 0
0.1 0.5 0.05 0.1 0.1 0.1 0.1 0.01 0.01 0.001
1 1 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0
0.4 1.2 2.3 1.7 12 18
open burn sites ash/soil (ng/g) mean range
railroad car incineration ash/soil (ng/g) n mean range
n
ash mean
(nfdg) range
n
10 11 12 10 15 16
0.24 0.25 0.49 1.3 2.6 7.2
(0.01-1.7) (0.01-3.2) (0.01-3.9) (0.07-7.1 (0.05-220) (0.1-232)
9 14 13 12 15 15
0.24 0.13 0.33 0.39 1.2 3.4
(0.04-0.6) (0.01-0.9) (0.02-2.3) (0.03-3.9) (0.08-12) (0.25-51)
11 0.034 12 0.045 12 0.097 12 0.20 13 1.8 13 11
(0.01-0.29) (0.01-0.39) (0.01- 0.42) (0.02-0.75) (0.12-12) (0.97-77) (0.01-0.86) (0.004-0.36) (0.004-0.42) (0.013-1.1) (0.005-4.6) (0.005-0.66) (0.01-0.54) (0.04-2.6) (0.01-0.35) (0.07-5.8) (0.02-2.2) (0.009-0.90)
15 35 10 46 12 5 5 71 25 100 76 19
15 6.4 16 2.9 16 1.4 16 5.9 16 1.8 12 1.6 16 0.92 16 12 14 3 16 14 16 10 16 2.9
(0-49- 590) (0.01-792) (0.01-140) (0.06-430) (0.02-180) (0.02-32) (0.03-44) (0.16-520) (0.01-160) (0.12- 1200) (0.03-1600) (0.02-250)
15 15 15 15 15 15 15 12 15 15 15 15
1.7 0.58 0.66 2.7 0.76 0.49 0.66 4.3 0.71 6.6 3.9 1.3
(0.04-17) (0.01-22) (0.01-14) (0.08-44) (0.02-13) (0.02-5.2) (0.06-8.7) (0.08-70) (0.01-27) (0.25-150) (0.08-51) (0.07-14)
13 13 13 13 13 13 13 13 13 13 13 13
2 4 24 18 50
11 1.4 12 2.7 15 4.1 16 7.2 16 15
(0.01-39) (0.02-120) (0.05-220) (0.1 -230) (0.17-450)
10 15 15 15 15
2.8 0.98 2.0 3.4 8.5
(0.05-13) (0.01-1 1) (0.14- 18) (0.25-51) (0.39-88)
13 0.27 13 0.72 13 3.6 13 11 13 16
(0.01-1.5) (0.07-1.9) (0.23-22) (0.97-77) (1.2-100)
15 16 16 16 16 16
(0.49-590) (0.1-940) (0.02-680) (0.1 6-680) (0.12-1200) (0.39-4000)
15 5.6 15 7.0 15 7.6 15 7.4 15 6.6 15 40
(0.1 -84) (0.1-180) (0.2-97) (0.27-94) (0.25-190) (0.97-440)
13 13 13 13 13 13
(0.01-3.1) (0.04-3.3) (0.05-4.0) (0.09-4.6) (0.07-5.8) (0.31 - 16)
23 110 88 110 100 460
14 12 12 17 14 71
0.21* 0.06* 0.089" 0.23* 0.089* 0.089* 0.067* 0.72* 0.083* 0.86' 0.49" 0.20*
0.62* 0.77* 0.92* 1.24* 0.86" 5.0*
a A n asterisk ( + I indicates significantly different ( p < 0.011 from mean levels in ashlsoil at metal recoveryfacilities and open burn sites. Congener levels not determined are not included in n, mean, range, or TEQ calculation.
car incineration facility. The fly ash samples contain notably higher levels than all other groups for all parameters. The geometric mean ITEQ concentration in the flyash (two samples each analyzed twice) is 19 pg of ITEQlg or parts per million (ppm). Excluding the one fly ash analysis with the 100-500% higher concentrations than the other three analyses minimally impacted mean concentrations with the mean ITEQ decreasing to 14 ppm. The fly ash samples were excluded from further statistical analysis due to the small number of samples. The log-transformed values for d congeners, homologues, and TEQ concentrations within the remaining three groups follow a Gausian distribution (W-test for normality not rejected). For the two field replicate soil/ash samples from the copper wire and aluminum smelting facility that were analyzed for TCDD, the concentrations are '0.48 and
