Characterization of Persistent Organic Pollutants Emitted from a Municipal Solid Waste Incinerator in Taiwan

Abstract

No information is currently available on the emission of brominated flame retardant (BFR) compounds from stack flue gases of municipal solid waste incinerators (MSWIs) because of the limitations of standard methods of BFR sampling and analysis. This study presents sample cleanup procedures that are combined with a multiple column approach to determine the quantities of five persistent organic pollutants (polychlorinated dibenzo-p-dioxins/dibenzofurans [PCDD/Fs], polybrominated dibenzo-p-dioxins/dibenzofurans [PBDD/Fs], polybrominated diphenyl ethers [PBDEs], polychlorinated biphenyls [PCBs], and polybrominated biphenyls [PBBs]) simultaneously from single stack gas samples collected from a large-scale MSWI in Taiwan. Mean concentrations of PCDD/Fs, PBDD/Fs, PCBs, PBDEs, and PBBs in the flue gases of MSWI were 0.0719 ng WHO-TEQ/(N·m³), 0.00169 ng WHO-TEQ/(N·m³), 0.00546 ng WHO-TEQ/(N·m³), 20.7 ng/(N·m³), and 0.958 ng/(N·m³), respectively. Emission factors of PCDD/Fs, PBDD/Fs, PCBs, PBDEs, and PBBs were 0.300 μg WHO-TEQ/ton-waste, 0.00667 μg WHO-TEQ/ton-waste, 0.0207 μg WHO-TEQ/ton-waste, 84.5 μg/ton-waste, and 1.05 μg/ton-waste, respectively. Therefore, the emissions of not only PCDD/Fs but also BFRs from MSWIs should be of concern and further investigation is needed.

Introduction

Persistent organic pollutants (POPs), such as chlorinated and brominated aromatics, have been of great concern because of their persistence in the global environment. POPs are lipophilic and may bioaccumulate in the food chain, posing a potential threat to human health (Jones and de Voogt, 1999). Many such compounds are considered to act as environmental hormones, which disrupt the reproductive cycles of humans and wildlife. Polychlorinated compounds (such as polychlorinated dibenzo-p-dioxins/dibenzofurans [PCDD/Fs] or biphenyls [PCBs]) are known to be stable in the environment. These compounds have been detected in emissions from various sources, including waste incinerators, chemical plants, other thermal sources, and workplace environments (Alcock et al., 1998; Chang et al., 1999; Lohmann et al., 2001; Kim et al., 2004; Mari et al., 2008). However, interest in the closely related brominated compounds is lacking, partially because of the lack of standard methods for sampling and analyzing these compounds.

Polybrominated diphenyl ethers (PBDEs) and biphenyls (PBBs) are examples of common additive brominated flame retardants (BFRs) that are used in a wide range of commercial and industrial applications to prevent fire (WHO, 1994). The structural similarity between both polybrominated dibenzo-p-dioxins/dibenzofurans (PBDD/Fs) and PCDD/Fs results in the similarity of mechanisms of formation of these compounds during thermal treatments in de novo synthesis and/or the thermolysis of precursor compounds (such as brominated aromatic compounds) (Weber and Kuch, 2003). The toxicity of PBDD/Fs is comparable to that of their chlorinated analogs (Wilken et al., 1990; Weber and Greim, 1997; Behnisch et al., 2003; Samara et al., 2009), so PBDD/Fs and other BFRs have become serious environmental concerns in the past decade.

BFRs have been identified in electronic recycling plants and other similar working environments (Sjödin et al., 2001), aluminum recycling plants (Sinkkonen et al., 2003), and municipal waste incinerators (Söderström and Marklund, 2000). With respect to PBDD/Fs, several studies have focused on their thermal treatments in laboratory-scale reactors (Sakai et al., 2001; Söderström and Marklund, 2002), but the data of PBDD/F emissions from combustion are rarely available. Wang and Chang-Chien (2007) observed that the mean concentrations of PBDD/Fs (sum of seven tetra- to hexa-PBDD/F congeners) were 2.28 and 18.2 pg/(N·m³) from municipal and industrial incinerators in Taiwan, respectively. The concentrations of total PBDD/Fs (sum of 17 tri- to octa-BDD/Fs) in flue gases of a U.S. waste combustor ranged from 1.41 to 16.5 pg/(N·m³) (Wyrzykowska et al., 2008). Recently, Wang et al. (2010a, 2010b) have reported that the total PBDD/Fs (sum of 12 tri- to octa-BDD/Fs) and PBDEs (sum of 30 BDEs) in the stack flue gases of the municipal solid waste incinerators (MSWIs) were 65.3–88.1 pg/(N·m³) and 26.1–109 ng/(N·m³), respectively. To the best of our knowledge, data on levels of BFRs (such as PBDD/F, PBDE, and PBB) along with PCB and PCDD/F in the stack flue gases of large-scale continuous MSWIs have not yet been studied.

In this study, the characteristics of five target compounds (2,3,7,8-substituted PCDD/Fs and PBDD/Fs, PBDEs, PCBs, and PBBs) in the stack flue gases of a large-scale continuous MSWI were investigated. The emission concentrations and factors of the five target compounds were determined. The congener profiles of these target compounds were analyzed to identify possible emission sources.

Experimental

Sampling

A large-scale continuous MSWI in southern Taiwan was investigated. The MSWI had a capacity of 1,350 tons day⁻¹ and was equipped with air pollution control devices (APCDs), which were a dry scrubber, an activated carbon injector, and a bag filter. Table 1 presents basic information on the incinerator.

Table 1.

Basic Information for the Municipal Solid Waste Incinerator

Design type	Modular incinerator with excess air
Operating type	Continuous
Feeding material	Municipal solid waste
Capacity	1,350 tons day⁻¹
Emission temperature of stack flue gas	150°C
Stack height	60 m
Air pollution control devices in sequence (operation temperature)	Selective noncatalytic reduction + semidry scrubber + activated carbon injection + fabric filter

All the stack flue gases were sampled during normal operating periods and at least 1 month after the start-up procedure to eliminate any possible memory effect from the MSWI. The stack flue gas sampling procedures were collected isokinetically following USEPA Modified Method 23 (USEPA, 1996) using USEPA Modified Method 5 samplings train (USEPA, 2001). Ten stack flue gas samples were taken from the MSWI, and each stack gas sampling lasted for 2–3 h. Before sampling, XAD-2 resin was spiked with PCDD/Fs surrogate standards that had been prelabeled with isotopes (³⁷C_l4-2,3,7,8-TeCDD, ¹³C₁₂-2,3,4,7,8-PeCDF, ¹³C₁₂-1,2,3,4,7,8-HxCDD, ¹³C₁₂-1,2,3,4,7,8-HxCDF, and ¹³C₁₂-1,2,3,4,7,8,9-HpCDF). The recoveries of PCDD/Fs surrogate standards were 82%–115%, which were within the acceptance criteria (70%–130%) for PCDD/Fs specified in the USEPA Modified Method 23 (USEPA, 1996), indicating good collection efficiency of the sampling train. The PCB surrogate standards are not specified in USEPA Modified Method 23, and those of PBDD/F, PBDE, and PBB could not be purchased. The recoveries of corresponding PCDD/F surrogate standards were used to check sampler collection efficiencies for PBDD/Fs, although the PBDE concentrations were not corrected for the sampler collection efficiencies (Wang and Chang-Chien, 2007; Wang et al., 2008), and PBBs and PCBs were also not corrected. Note that modification of presampling solutions is under consideration to provide necessary information on sampling efficiency and potential losses (or contamination) during transportation and sampling.

Extraction, cleanup, and gas chromatograph/mass spectrometer analysis

The internal standards used for identification and quantification of the known substances in this study were purchased from Cambridge Isotope Laboratories, Inc. and Wellington Laboratories. The analyses of the stack flue gases were performed according to the USEPA Modified Method 23 (USEPA, 1996). Figure 1 depicts the clean-up procedure for analyzing the PCDD/Fs, PBDD/Fs, PBDEs, PCBs, and PBBs samples. ¹³C-labeled ISs (PCDD/Fs, PBDD/Fs, PBDEs, and PCBs) were added to samples that were then extracted for 24 h in Soxhlet extractors with toluene. The extract was concentrated by rotary evaporation in an N₂ gas stream, and then transferred to a vial. The concentrated extract was then treated by a series of simultaneous sample cleanup and fraction procedures, including the use of silica gel, alumina, and active carbon columns.

FIG. 1.

Scheme of sample clean-up and fractionation for the analysis of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), polybrominated dibenzo-p-dioxins/dibenzofurans (PBDD/Fs), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and polychlorinated biphenyls (PBBs).

After extraction, the extracted solution was divided equally into flasks A and B. Flask A was used to determine the amounts of POPs with the addition of alternate standards, whereas flask B was stored for future use. Ten gas samples from each sampling of MSWI were analyzed for PCDD/Fs, PBDEs, PCBs, and PBBs. The detection limit required that two or three gas samples were concentrated into a combined sample in the extraction stage for PBDD/Fs analysis. Therefore, only four PBDD/F datasets were obtained from the MSWI.

The instrumental analyses of five target compounds were conducted separately using a high-resolution gas chromatograph/high-resolution mass spectrometer. The high-resolution gas chromatograph (Hewlett-Packard 6970 Series gas) was equipped with a silica capillary column (J&W Scientific) and a splitless injector, and the high-resolution mass spectrometer (Micromass Autospec Ultima) had a positive electron impact source. The authors' earlier work detailed the conditions for the analysis of the target compounds (Wang et al., 2010c).

Quality assurance and quality control

Target compounds in the gas samples were identified using the following criteria. The relative retention time of the target compounds matched the corresponding authentic standards (tolerance relative retention time = ± 0.5%); the limit of detection was defined as the amount at which the signal-to-noise ratio was 3 or above; the isotopic ratio of at least two characteristic ions had practical values that deviated by up to 15%. The target compounds were quantified by analyzing calibration mixtures that contained isotopically labeled internal standards. The ¹³C₁₂-labeled internal standards, as noted above, were spiked into the stack flue samples prior to their preparation for GC/MS analysis. Method detection limits (MDLs) of target compound analyses were determined using the standard deviations obtained from the analyses of seven matrix-spiked samples. The limit of quantification was determined at the signal-to-noise ratio of 10 or above. One field blank was taken during the individual sampling events to evaluate contamination during sampling. Field blanks were air-proofed and loaded into the sampling system. Such field blanks experienced the same handling, storage, and analysis procedures as the real samples. Laboratory blanks were analyzed for each batch of analyses.

Results and Discussion

Quality assurance and quality control results

The recoveries of target compounds in the flue gases were quantitatively checked before extraction and cleanup using ¹³C₁₂-labeled internal standards. Table 2 presents the average recoveries and RSDs of the ¹³C₁₂-labeled internal standards (PBDD/Fs, PCDD/Fs, PBDEs, and PCBs). The average recoveries of ¹³C₁₂-labeled PBDEs ranged from 47% to 133% (RSD = 5.6%–27%), meeting the USEPA Method 1614 (USEPA, 2007) criteria of 25%–150% for the di- to nona-PBDE congeners and 20%–200% for deca-BDE. Mean recoveries of PCBs and PBDD/Fs were 93%–106% (RSD = 3.1%–7.2%) and 58%–133% (RSD = 6.9%–23%), respectively, fulfilling the criteria of USEPA Method 1668A (USEPA, 1999a) (25%–150%) and those of USEPA Method TO-9A (USEPA, 1999b) (40%–130%). The recoveries of ¹³C₁₂-labeled internal standards added to the samples before extraction for the tetra- to hexa-PCDD/F congeners and the hepta- to octa-PCDD/Fs were within the USEPA Modified Methods 23 control limits of 40%–130% and 25%–130%, respectively. Because of limited availability of individual PBB standards, their recoveries could not be determined. The method detection limits (MDLs) for the developed sample preparation were determined from the standard deviations obtained from the analyses of matrix-spiked samples. The MDLs of air samples for PBDD/Fs, PBDEs, PCDD/Fs, PCBs, and PBBs were 0.070–25.7, 0.262–333, 0.202–6.27, 0.189–6.29, and 0.0731–8.3 pg, respectively.

Table 2.

Quality Assurance and Quality Control Results on Polybrominated Dibenzo-p-Dioxins/Dibenzofurans, Polychlorinated Dibenzo-p-Dioxins/Dibenzofurans, Polychlorinated Biphenyls, and Polybrominated Diphenyl Ethers in Stack Flue Gases of the Municipal Solid Waste Incinerator (N = 10)

Labeled standards	Average (%)	RSD (%)	Labeled standards	Average (%)	RSD (%)
¹³C₁₂-2,3,7,8-TeBDF	116	6.9	¹³C₁₂-PCB 77	106	7.2
¹³C₁₂-1,2,3,7,8-PeBDF	104	15	¹³C₁₂-PCB 81	100	7.2
¹³C₁₂-2,3,4,7,8-PeBDF	90	12	¹³C₁₂-PCB 105	102	5.0
¹³C₁₂-1,2,3,4,7,8-HxBDF	87	21	¹³C₁₂-PCB 114	101	4.5
¹³C₁₂-1,2,3,4,6,7,8-HpBDF	69	17	¹³C₁₂-PCB 118	101	5.4
¹³C₁₂-OctBDF	58	21	¹³C₁₂-PCB 123	101	5.0
¹³C₁₂-2,3,7,8-TeBDD	133	13	¹³C₁₂-PCB 126	103	3.1
¹³C₁₂-1,2,3,7,8-PeBDD	107	9.8	¹³C₁₂-PCB 156	97	5.5
¹³C₁₂-1,2,3,4/6,7,8-HxBDD	102	23	¹³C₁₂-PCB 157	97	6.8
¹³C₁₂-1,2,3,7,8,9-HxBDD	96	9.7	¹³C₁₂-PCB 167	106	5.1
¹³C₁₂-1,2,3,4,6,7,8-HpBDD	116	6.9	¹³C₁₂-PCB 169	96	4.5
¹³C₁₂-OctBDD	104	15	¹³C₁₂-PCB 189	93	5.2
¹³C₁₂-2,3,7,8-TeCDD	95	3.0	¹³C₁₂-BDE 15	110	5.6
¹³C₁₂-1,2,3,7,8-PeCDD	103	11	¹³C₁₂-BDE 28	110	22
¹³C₁₂-1,2,3,6,7,8-HxCDD	91	4.1	¹³C₁₂-BDE 47	133	19
¹³C₁₂-1,2,3,4,6,7,8-HpCDD	89	6.3	¹³C₁₂-BDE 99	106	26
¹³C₁₂-OctCDD	76	12	¹³C₁₂-BDE 154	93	21
¹³C₁₂-2,3,7,8-TeCDF	88	3.1	¹³C₁₂-BDE 153	93	22
¹³C₁₂-1,2,3,7,8-PeCDF	93	8.7	¹³C₁₂-BDE 183	62	27
¹³C₁₂-1,2,3,6,7,8-HxCDF	95	4.2	¹³C₁₂-BDE 197	78	19
¹³C₁₂-1,2,3,4,6,7,8-HpCDF	91	4.5	¹³C₁₂-BDE 207	56	13
			¹³C₁₂-BDE 209	47	16

The average recoveries of PBDEs Precision and Recovery (PAR) standards for sample batchs were 62%–137%, whereas those of PBDD/Fs PAR standards were 95%–127%, both meeting the criteria of being within the range 60%–140% set by the Taiwan EPA (2004). The recoveries of PCDD/Fs PAR standards for the tetra- through octa-chlorinated homologs were between 100% and 122%, satisfying the requirement for PCDD/F analysis (within 70%–130%). The recoveries of PCBs and PBBs ranged from 104% to 116% and from 96% to 104%, respectively, falling within the range 60%–140%, as required. Accordingly, the simultaneous preparation of five-group compounds using multiple columns yielded high recovery and efficiency of determination of their concentrations from one single sample extraction procedure.

PCDD/F and PBDD/F concentrations

The mean PCDD/F International Toxic Equivalent (I-TEQ) was 0.059 ng I-TEQ/(N·m³) (0.072 ng WHO₂₀₀₅-TEQ/[N·m³]) (Table 3), lower than the PCDD/F emission standard (0.1 ng I-TEQ/[N·m³]) of large-scale MSWIs set by the Taiwan EPA (1997). The ratio of PCDD International Toxic Equivalent (I-TEQ) to PCDF equivalent was 0.595, indicating that most of the toxic equivalent in the stack flue gas of MSWI was associated with PCDFs. The PCDD/F levels obtained from this study are comparable to our previous findings (Wang et al., 2005; Wang and Chang-Chien, 2007; Chen et al., 2008). Figure 2a shows congener profiles of the 17 PCDD/Fs (mean ± SD) that were detected in the stack of MSWI. Each selected congener was normalized to the total weight of all 2,3,7,8-congeners. The concentrations of 2,3,7,8-PCDD/Fs homologs increased with the degree of chlorine substitution and so higher chlorinated congeners dominated in all flue gas samples. The five dominant PCDD/Fs were OCDD (35.9%), 1,2,3,4,6,7,8-HpCDD (22.8%), 1,2,3,4,6,7,8-HpCDF (10.9%), OCDF (8.96%), and 2,3,4,6,7,8-HxCDF (4.12%). The congener profile of the MSWI is similar to those presented in literature (Lee et al., 2004; Wang et al., 2005; Wang and Chang-Chien, 2007).

FIG. 2.

(a–e) PCDD/F, PBDD/F, PBDE, PCB, and PBB congener profiles in stack flue gases of the municipal solid waste incinerator.

Table 3.

Mean Concentrations of Polychlorinated Dibenzo-p-Dioxins/Dibenzofurans (ng/[N·m³]) and Polybrominated Dibenzo-P-Dioxins/Dibenzofurans (pg/[N·m³]) in Stack Flue Gases of the Municipal Solid Waste Incinerator

	Compounds	Range	Mean	RSD (%)
PCDD/Fs (n = 10)	PCDDs	0.700–3.16	1.45	59
	PCDFs	0.306–1.51	0.734	62
	PCDDs/PCDFs ratio	1.82–2.40	2.04	28
	Total (ng/[N·m³)	1.04–4.68	2.18	60
	Total I-TEQ (ng I-TEQ/[N·m³])	0.0272–0.113	0.059	55
	Total WHO-TEQ (ng WHO₂₀₀₅-TEQ/[N·m³])	0.0301–0.140	0.072	62
PBDD/Fs (n = 4)^a	2,3,7,8,-TeBDD	0.00820^b	0.00820^b	—
	1,2,3,7,8-PeBDD	0.0937–0.336	0.204	63
	1,2,3,4/6,7,8-HxBDD	0.443–1.84	0.889	74
	1,2,3,7,8,9-HxBDD	0.0562^b	0.0562^b	—
	1,2,3,4,6,7,8-HpBDD	0.335^b	0.335^b	—
	OBDD	0.380^b	0.380^b	—
	2,3,7,8-TeBDF	0.0122–0.458	0.295	66
	1,2,3,7,8-PeBDF	0.0304–0.297	0.221	58
	2,3,4,7,8-PeBDF	0.671–0.992	0.841	18
	1,2,3,4,7,8-HxBDF	3.14–5.25	4.04	22
	1,2,3,4,6,7,8-HpBDF	50.7–82.4	64.1	21
	OBDF	38.8–362	152	98
	Total (pg/[N·m³])	97.1–433	223	69
	Total I-TEQ (pg I-TEQ/[N·m³])	1.71–3.68	2.66	34
	Total WHO-TEQ (pg WHO₂₀₀₅-TEQ/[N·m³])	1.59–1.90	1.69	8.9
Ratio of PBDD/Fs to PCDD/Fs	Mass ratio (%)	2.1–42	14	43
	TEQ ratio (%)	1.2–6.3	3.4	45

Because of the detection limit, only four PBDD/Fs data were obtained.

BD, below detection limit.

PCDD/Fs, polychlorinated dibenzo-p-dioxins/dibenzofurans; PBDD/Fs, polybrominated dibenzo-p-dioxins/dibenzofurans.

Compared with the PCDD/Fs with commonly reported 17 congeners, only 12 of possible 17 2,3,7,8-substituted PBDD/F congeners were reported in this study because standards of the left five congeners have not been commercially available yet. Presently, the existing information on toxic effects of PBDD/Fs is not sufficient to obtain complete toxicity equivalency factor (TEF) values of PBDD/Fs. According to some present surveys of several biological and toxicological parameters for animals, 2,3,7,8-TeBDD and 2,3,7,8-TeBDF are equipotent to 2,3,7,8-TeCDD and 2,3,7,8-TeCDF. To assess the toxicologically relevant information on PBDD/Fs, WHO (1998) recommends the use of the same TEF values for PBDD/Fs as described for the chlorinated analogs. Accordingly, we calculated the I-TEQ values for PBDD/Fs using the concentrations of seven 2,3,7,8-brominated substitutes and the TEFs of their chlorinated analogs. The mean PBDD/F content (sum of 12 2,3,7,8-substituted congeners) in the stack flue gases of MSWI was 223 pg/(N·m³) (range = 97.1–433, RSD = 69%), with a corresponding mean TEQ of 2.66 pg I-TEQ/(N·m³) (range = 1.71–3.68, RSD = 34%). The sum of the concentrations of seven tetra-hexa congeners (2.51 pg/[N·m³], TEQ content = 0.666 pg I-TEQ/m³) in this study slightly exceeds that (sum of concentrations of same seven congeners) (2.28 pg/[N·m³], TEQ = 0.557 pg I-TEQ/m³) in nine MSWIs in Taiwan, presented elsewhere (Wang and Chang-Chien, 2007). This result is attributed to the use of different furnaces and/or APCDs and the difference between the bromine contents in the feeding wastes in this and the cited studies. The mean PBDD/F concentrations of flue gases in this study are comparable to those in air. The mean PBDD/F content (223 pg/[N·m³]) obtained in this study is around 2 orders of magnitude greater than the PBDD/F levels (sum of levels of 11 mono- to octacongeners) (0.38–11 pg/[N·m³]) in the atmosphere of Osaka district in Japan (Hayakawa et al., 2004) and those (seven congeners) (15–30 pg/[N·m³]) in the air in urban Taiwan (Wang et al., 2008). The observed mean PBDD/F content (223 pg/[N·m³]) is ∼533 times higher than our previous finding for ambient air around the selected MSWI in southern Taiwan (Wang et al., 2010c). Accordingly, the MSWI might be a major source of PBDD/F emission in the local area. With respect to PBDD/Fs, PBDF was dominant in all samples and the most abundant congeners were 1,2,3,4,6,7,8-HpBDF and OBDF, accounting for 28.7% and 68.0% of the total PBDD/F mass, respectively (Fig. 2b). The PBDD/F congener profiles of stack are similar to those observed in the atmosphere (Hayakawa et al., 2004; Wang et al., 2008).

The total TEQ level of PBDD/Fs in the flue gas of MSWI was lower than that of PCDD/Fs, with a mean mass ratio of PBDD/F to PCDD/F of 14% (range = 2.1%–42%, RSD = 43%) and a corresponding mean TEQ ratio of 2.2% (range = 0.55%–5.1%, RSD = 48%) (Table 3), revealing that more PCDD/Fs were formed than PBDD/Fs during the combustion of waste. The Pearson correlation analyses were conducted to study the relationships between the PCDD/F and PBDD/F TEQ levels of the samples. A significant correlation (p = 0.040) exists between the PCDD/F and PBDD/F TEQ levels in the flue gas of MSWI, revealing that they are formed by similar mechanisms in the incineration system and have similar removal rates by APCDs. This finding is consistent with that in an earlier work (Wang and Chang-Chien, 2007).

PBDE concentrations

The concentration of total PBDE (sum of 30 BDEs) was in the range of 9.52–37.7 ng/(N·m³) with a mean of 20.7 ng/Nm³ (RSD = 47%) (Table 4). The emission of PBDEs from MSWIs with electronic recycling to the atmosphere has been identified (Agrell et al., 2004), but no information on PBDE emission from MSWIs is currently available.

Table 4.

Mean Concentrations of Polybrominated Diphenyl Ethers (ng/[N·m³]) in Stack Flue Gases of the Municipal Solid Waste Incinerator

Compounds		Range	Mean	RSD (%)
PBDEs (n = 10)	BDE-7	0.0123–0.0331	0.0197	37
	BDE-15	0.146–0.405	0.269	41
	BDE-17	0.0147–0.0954	0.0308	82
	BDE-28	0.0350–0.110	0.0685	39
	BDE-49	0.0138–0.0507	0.0267	48
	BDE-71	0.00276–0.0315	0.00886	96
	BDE-47	0.330–0.676	0.472	29
	BDE-66	0.0127–0.0551	0.0238	61
	BDE-77	0.000194–0.00478	0.00289	108
	BDE-100	0.0556–0.170	0.0789	43
	BDE-119	0.00452–0.0287	0.00710	107
	BDE-99	0.314–0.848	0.414	39
	BDE-85	0.0152–0.0540	0.0229	51
	BDE-126	0.0000887–0.00150	0.000487	131
	BDE-154	0.0330–0.0901	0.0478	37
	BDE-153	0.0483–0.113	0.0690	31
	BDE-139	0.00312–0.0131	0.00749	47
	BDE-140	0.00249–0.0153	0.00781	51
	BDE-138	0.00807–0.0203	0.0127	37
	BDE-156	0.000260–0.00331	0.000925	120
	BDE-184	0.000826–0.0156	0.00391	136
	BDE-183	0.0664–0.197	0.121	35
	BDE-191	0.00221–0.0536	0.0189	95
	BDE-197	0.0546–0.339	0.124	72
	BDE-203	0.0389–0.174	0.0955	42
	BDE-196	0.0717–0.350	0.150	56
	BDE-208	0.296–1.87	0.706	64
	BDE-207	0.369–3.80	1.21	84
	BDE-206	0.408–2.76	1.05	64
	BDE-209	5.78–28.5	15.6	52
	Σ_{2–8 Br} BDEs	1.51–3.18	2.11	30
	Σ_{9–10 Br} BDEs	7.88–34.6	18.6	50
	Total (ng/[N·m³])	9.52–37.7	20.7	47
Ratio of PBDEs to PCDD/Fs	Mass ratio (%)	271–3,491	1,285	53

PBDEs, polybrominated diphenyl ethers.

One previous work reported total atmospheric levels of 4.5–65 pg/(N·m³) for the mono- to nona-BDEs in Japan (Hayakawa et al., 2004), whereas Agrell et al. (2004) observed atmospheric PBDE concentrations in the range 2.24–21.3 pg/(N·m³) near an MSWI in Europe. The average concentrations of tri- to deca-BDE congeners ranged from 39.1 to 4,105 pg/m³ (mean = 1,068 pg/m³) in the daytime and from 33.7 to 1,649 pg/m³ (mean = 439 pg/m³) in the nighttime at an E-waste dismantling site (Guiyu) in China; BDE-47, −99, and −209 concentrations were extraordinarily high at the site (Chen et al., 2009). These observations are 2–3 orders of magnitude lower than that in this study (20,700 pg/m³). The 20,700 pg/m³ value is also much higher than the atmospheric concentrations (25.7–100 pg/[N·m³]) of total PBDE (sum of 30 BDEs) for the MSWI in our previous investigation (Wang et al., 2010c), leading to a high ratio (397) of the mean concentration of stack flue gas PBDE (20,700 pg/m³) to that in atmosphere (52.1 pg/[N·m³]). Therefore, the MSWI is an important local PBDE emission source.

Followed by BDE 206 and BDE 207, BDE 209 was the dominant congener among PBDEs in the stack flue gas, accounting for more than 76% of total PBDEs (Fig. 2c). Similarly, Hayakawa et al. (2004) and Agrell et al. (2004) found that BDE 209 dominated in PBDEs in the atmosphere in an urban area in Japan and at an MSWI in Europe, respectively. With 23,000 metric tons of market demand in 2001, deca-BDE formulation was historically main technical BDE-based flame retardant used in Asia, whereas penta-BDE had only 150 metric tons of market demand in the same year (Birnbaum and Staskal, 2004). As the used PBDE formulation has been changed from penta- to deca-BDE (Agrell et al., 2004), BDE-209 is the main congener of commercial deca-BDE mixtures and has a larger production volume than other commercial PBDE mixtures. Therefore, BDE-209 was dominant in concentration in the flue gases of the MSWIs and the atmosphere near MSWIs.

According to Pearson correlation analyses, a positive correlation (r = 0.310, p = 0.0165) exists between the PBDD/F concentrations and the logarithms of PBDE concentrations of flue gases. This finding suggests that PBDD/F emission via the flue gases of MSWI was associated with the use of PBDEs as BFRs in electrical products or thermal desorption of PBDEs from PBDE-based BFRs in the feeding wastes of incinerator (Hanari et al., 2006). Nevertheless, further study should be performed to identify emission sources of PBDEs and their effects on the atmospheric environment.

PCB and PBB concentrations

Table 5 presents the concentrations of PCB congeners (represented by their International Union of Pure and Applied Chemistry numbers) in flue gases. The TEQ concentrations of PCB congeners were calculated using WHO 2005 TEF values (Van den Berg et al., 2006). The concentrations of total TEQ ranged between 0.00319 and 0.00750 ng TEQ/(N·m³) (mean = 0.00489 ng TEQ/[N·m³], RSD = 34%), similar to those (mean = 0.006 ng TEQ/[N·m³]) in stack gases of an MSWI in Taiwan (Chi et al., 2006). However, the PCB levels in this study are lower than the mean PCB level (1.72 ng TEQ/[N·m³]) of nine MSWIs in Korea (Chang et al., 1999) and about 1–4 orders of magnitude lower than the total PCBs level (sum of 160 congeners) from eight incinerators in Japan (0.02–44 ng TEQ/[N·m³]) (Kim et al., 2004). In addition to variances of feeding materials and operating conditions, the APCDs may be responsible for the different MSWI PCB levels observed in different studies.

Table 5.

Mean Concentrations of Polychlorinated Biphenyls (ng/[N·m³]) and Polybrominated Biphenyls (ng/[N·m³]) in Stack Flue Gases of the Municipal Solid Waste Incinerator

Compounds		Range	Mean	RSD (%)
PCBs (n = 10)	PCB 77	0.0948–0.123	0.111	14
	PCB 81	0.0144–0.0209	0.0187	10
	PCB 105	0.0293–0.0504	0.0406	16
	PCB 114	0.00721–0.00972	0.00851	11
	PCB 118	0.0491–0.0838	0.0633	18
	PCB 123	0.00384–0.00627	0.00501	14
	PCB 126	0.0297–0.0693	0.0454	33
	PCB 156	0.0183–0.0372	0.0278	25
	PCB 157	0.0121–0.0316	0.0203	40
	PCB 167	0.00758–0.0131	0.0104	19
	PCB 169	0.0127–0.0520	0.0298	52
	PCB 189	0.0186–0.0480	0.0304	41
	Total (ng/[N·m³])	0.327–0.479	0.411	13
	Total WHO-TEQ (ng WHO₂₀₀₅-TEQ/[N·m³])	0.00353–0.00851	0.00546	36
PBBs (n = 10)	PBB-15	0.182–0.382	0.248	27
	PBB-52	0.000442–0.459	0.0670	106
	PBB-153	0.00302^a–0.0162	0.00528	92
	PBB-180	0.476^a	0.476^a	—
	PBB-194	0.162^a	0.162^a	—
	Total (ng/[N·m³])	0.849–1.36	0.958	16
Ratio of PCBs to PCDD/Fs	Mass ratio (%)	14–41	25	22
	TEQ ratio (%)	6.0–13	9.1	27
Ratio of PBBs to PCDD/Fs	Mass ratio (%)	22–84	58	46

PCBs, polychlorinated biphenyls; PBBs, polybrominated biphenyls.

BD, below detection limit.

Figure 2d shows dioxin-like PCB congener compositions in the flue gas samples. PCB 77 (followed by PCB 118 [∼15.4%]) was predominant in the flue gases, accounting for 26.9% of total PCBs, consistent with the observation at an MSWI but different from that from an industrial waste incinerator in Taiwan (Chi et al., 2006). This result was attributed to unstable operating and waste feeding conditions of the industrial waste incinerator. The total TEQ level of PCBs was lower than that of PCDD/Fs, with a mean ratio of PCB TEQ to PCDDF TEQ of 3.4% (range = 2.0%–4.8%, RSD = 27%). Although PCBs and PCDD/Fs have similar properties and mechanisms of formation, higher distributions of PCBs in the vapor phase (Chi et al., 2006) may result in higher removal efficiencies for PCBs than for PCDD/Fs by APCDs.

Again, Pearson correlation analyses demonstrate a positive correlation (r = 0.794, p = 0.00205) between the PCDD/F and PCB concentrations in flue gases; the PCB TEQ concentrations were also significantly correlated with the PCDD/F TEQ concentrations (r = 0.975, p = 0.00107). The strong correlation between PCBs and PCDD/Fs in mass and TEQ concentrations may be explained by their similar mechanisms of formation and the potential precursors from PCBs to PCDD/Fs (Chang et al., 1999).

Table 5 presents the concentrations of total PBB, ranging from 0.849 to 1.36 ng/(N·m³) (mean = 0.958 ng/[N·m³], RSD = 16%). Among the investigated PBBs, PBB 180 was the dominant species in stack gases (Fig. 2e). Because of limitations in both the standard analytical methods and the reference materials, PBBs in the stack gases have not yet been reported. The mean concentration of PBBs in the MSWI stack gases (958 pg/[N·m³]) is much higher than that in the atmosphere (0.341 pg/[N·m³]) (Wang et al., 2010c), and the ratio of mean PBB mass (MWSI to the atmosphere) was 2,809, revealing that the MSWI is an important PBB emission source to the surrounding environment. For the MSWI, the PBB concentration was correlated positively with the PBDE concentration (r = 0.430, p = 0.0181) but negatively with the log(PBDD/F) concentration (r = −0.780, p = <0.00), indicating that more PBDD/Fs were generated than PBBs under poor combustion conditions. The positive correlation between PBBs and PBDEs in mass concentration is associated with the fact that technical PBDE formulations contain PBB impurities (Hanari et al., 2006).

TEQ contributions of dioxin-like compounds

The contributions of PCBs and PBDD/Fs to total WHO-TEQ (sum of WHO-TEQ concentrations of 17 PCDD/Fs, 12 PBDD/Fs, and 12 dioxin-like PCBs) were calculated based on the sample volume and their corresponding WHO-TEFs. As shown in Tables 3 and 5, the WHO-TEQ values of PCDD/Fs, PBDD/Fs, and dioxin-like PCBs were 0.0719, 0.00169, and 0.00546 ng WHO₂₀₀₅-TEQ/(N·m³), respectively; moreover, 6.9% of total WHO-TEQ was from the dioxin-like PCBs, whereas 2.1% was from the PBDD/Fs. Accordingly, PCDD/Fs contributed more than 91% of the total WHO₂₀₀₅-TEQ in stack gases. Although PBDD/Fs and dioxin-like PCBs contribute limitedly to total WHO-TEQ in the flue gases, the MSWI is a potential source of emission of dioxin-like compounds. Given the persistence and toxicity of PBDD/Fs and dioxin-like PCBs, a combined regulation is recommended to control their concentrations in stack flue gases of MSWIs.

Emission factors

Emission factors of POPs are useful parameters for evaluating their emission potentials. The emission factor (μg/ton-waste) of each target compound was calculated by multiplying the concentration of the compound in the stack gas with the gas flow rate on a dry basis and then dividing this product by the feeding rate of material (waste).

Table 6 lists the emission factors of PCDD/Fs, PBDD/Fs, PCBs, PBDEs, and PBBs in flue gases of the MSWI. The emission factor of PCDD/F (0.310 μg I-TEQ/ton-waste) herein is slightly higher than the value (mean = 0.223 μg/ton-waste) reported by Lin et al. (2007). Different feeding wastes and APCDs probably explain the discrepancy between studies. The total PCB emission factors (0.0207 μg WHO₂₀₀₅-TEQ/ton-waste [0.0204 μg WHO₁₉₉₈-TEQ/ton-waste]) observed from the MSWI in this study were comparable to that (0.014 ng WHO₁₉₉₈-TEQ/kg) from woodstove combustion in the United States (Gullett et al., 2003), but significantly lower than those (6.9–98.3 [mean = 26.4] μg WHO₂₀₀₅-TEQ/ton) from 43 small MSWIs (Choi et al., 2008).

Table 6.

Mean Emission Factors of Polychlorinated Dibenzo-p-Dioxins/Dibenzofurans, Polybrominated Dibenzo-P-Dioxins/Dibenzofurans, Polychlorinated Biphenyls, Polybrominated Diphenyl Ethers, and Polybrominated Biphenyls in Stack Flue Gases of the Municipal Solid Waste Incinerator

	Total (μg/ton-waste)		Total I-TEQ (μg I-TEQ/ton-waste)		Total WHO₂₀₀₅-TEQ (μg WHO₂₀₀₅-TEQ/ton-waste)
Compounds	Mean	RSD (%)	Mean	RSD (%)	Mean	RSD (%)
PCDD/Fs (n = 10)	9.10	60	0.310	60	0.300	62
PBDD/Fs (n = 4)	0.925	69	0.00750	12	0.00667	9.0
PCBs (n = 10)	1.71	13	—	—	0.0207	36
PBDEs (n = 10)	84.5	47	—	—	—	—
PBBs (n = 10)	1.05	27	—	—	—	—

The PBDEs had the highest mean emission factor of all compounds of interest (Table 6). The mean emission factors of PBDEs (84.5 μg/ton-waste) estimated in this study were 2–21 times lower than those (1,200–1,800 μg/ton) from e-waste (such as home TVs) incineration processes in Japan and were lower than those of some industrial processes (such as manufacturing of PBDEs, dismantling and crushing, textile processing, plastic processing, and others) (Sakai et al., 2006). Incinerators are important sources of PBDE emission to the atmosphere (Sakai et al., 2006). However, other potential sources, such as PBDE material manufacturing and recycling, should also be considered.

Conclusions

This study developed sample cleanup procedures combined with a multiple column approach to determine simultaneously the levels of five POPs (PCDD/Fs, PBDD/Fs, PBDEs, PCBs, and PBBs) from single stack gas sample. The mean PCDD/F, PBDD/F, PCB, PBDE, and PBB concentrations in stack gases of an MSWI were 0.0719 ng WHO-TEQ/(N·m³), 0.00169 ng WHO-TEQ/(N·m³), 0.00546 ng WHO-TEQ/(N·m³), 20.7 ng/(N·m³), and 0.958 ng/(N·m³), respectively. Although the dioxin-like PCBs and PBDD/Fs represented only 6.9% and 2.1%, respectively, of the total WHO-TEQ (the sum of PCDD/Fs, PBDD/Fs, and dioxin-like PCBs), the MSWI is a potential source for dioxin-like compound emission. The emission factors of PCDD/Fs, PBDD/Fs, PCBs, PBDEs, and PBBs were 0.300 μg WHO-TEQ/ton-waste, 0.00667 μg WHO-TEQ/ton-waste, 0.0207 μg WHO-TEQ/ton-waste, 84.5 μg/ton-waste, and 1.05 μg/ton-waste, respectively, in flue gases of the MSWI. Therefore, in addition to PCDD/Fs, the emissions from MSWIs of other dioxin-like compounds (such as BFRs) should also be considered.

Author Disclosure Statement

No competing financial interests exist.

References

Agrell

, ter Schure

A.F.H.

, Sveder

, Bokenstrand

, Larsson

, Zegers

B.N.

2004. Polybrominated diphenyl ethers (PBDES) at a solid waste incineration plant I: Atmospheric concentrations. Atmos. Environ., 38:5139.

Alcock

R.E.

, Behnisch

P.A.

, Jones

K.C.

, Hagenmaier

1998. Dioxin-like PCBs in the environment—human exposure and the significance of sources. Chemosphere, 31:1457.

Behnisch

P.A.

, Hosoe

, Sakai

2003. Brominated dioxin-like compounds: In vitro assessment in comparison to classical dioxin-like compounds and other polyaromatic compounds. Environ. Int., 29:861.

Birnbaum

L.S.

, Staskal

D.F.

2004. Brominated Flame Retardants: cause for Concern? Environ. Health Perspect., 112:9.

Chang

Y.S.

, Kong

S.B.

, Ikonomou

M.G.

1999. PCBs contributions to the total TEQ released from Korean municipal and industrial waste incinerators. Chemosphere, 39:2629.

Chen

C.K.

, Lin

Y.C.

, Wang

L.C.

, Chang-Chien

G.-P.

2008. Polychlorinated dibenzo-p-dioxins/dibenzofuran mass distribution in both start-up and normal condition in the whole municipal solid waste incinerator. J. Hazard. Mater., 160:37.

Chen

, Bi

, Zhao

, Chen

, Tan

, Mai

, Sheng

, Fu

, Wong

2009. Pollution characterization and diurnal variation of PBDEs in the atmosphere of an E-waste dismantling region. Environ. Pollut., 157:1051.

Chi

K.H.

, Chang

S.H.

, Huang

C.H.

, Huang

H.C.

, Chang

M.B.

2006. Partitioning and removal of dioxin-like congeners in flue gases treated with activated carbon adsorption. Chemosphere, 64:1489.

Choi

K.I.

, Lee

S.H.

, Lee

D.H.

2008. Emissions of PCDDs/DFs and dioxin-like PCBs from small waste incinerators in Korea. Atmos. Environ., 42:940.

10.

Gullett

B.K.

, Touati

, Hays

M.D.

2003. PCDD/F, PCB, HxCBz, PAH, and PM emission factors for fireplace and woodstove combustion in the San Francisco bay region. Environ. Sci. Technol., 37:1758.

11.

Hanari

, Kannan

, Miyake

, Okazawa

, Kodavanti

P.R.

, Aldous

K.M.

, Yamashita

2006. Occurrence of polybrominated biphenyls, polybrominated dibenzo-p-dioxins, and polybrominated dibenzofurans as impurities in commercial polybrominated diphenyl ether mixtures. Environ. Sci. Technol., 40:4400.

12.

Hayakawa

, Takatsuki

, Watanabe

, Sakai

2004. Polybrominated diphenyl ethers (PBDEs), polybrominated dibenzo-p-dioxins/dibenzofurans (PBDD/Fs) and monobromo-polychlorinated dibenzo-p-dioxins/dibenzofurans (MoBPXDD/Fs) in the atmosphere and bulk deposition in Kyoto, Japan. Chemosphere, 57:343.

13.

Jones

K.C.

, de Voogt

1999. Persistent organic pollutants (POPs): state of the science. Environ. Pollut., 100:209.

14.

Kim

K.S.

, Hirai

, Kato

, Urano

, Masunaga

2004. Detailed PCB congener patterns in incinerator flue gas and commercial PCB formulations (Kanechlor) Chemosphere, 55:539.

15.

Lee

W.S.

, Chang-Chien

G.P.

, Wang

L.C.

, Lee

W.J.

, Tsai

P.J.

, Wu

K.Y.

, Lin

2004. Source identification of PCDD/Fs for various atmospheric environments in a highly industrialized city. Environ. Sci. Technol., 38:4937.

16.

Lin

L.F.

, Lee

W.J.

, Li

H.W.

, Wang

M.S.

, Chang-Chien

G.P.

2007. Characterization and inventory of PCDD/F emissions from coal-fired power plants and other sources in Taiwan. Chemosphere, 68:1642.

17.

Lohmann

, Ockenden

W.A.

, Shears

, Jones

K.C.

2001. Atmospheric distribution of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs), and non-ortho biphenyls (PCBs) along a north-south Atlantic transect. Environ. Sci. Technol., 35:4046.

18.

Mari

, Nadal

, Schuhmacher

, Domingo

J.L.

2008. Monitoring PCDD/Fs, PCBs and metals in the ambient air of an industrial area of Catalonia, Spain. Chemosphere, 73:990.

19.

Sakai

S.I.

, Hirai

, Aizawa

, Ota

, Muroishi

2006. Emission inventory of deca-brominated diphenyl ether (DBDE) in Japan. J. Mater. Cycles Waste Manag., 8:56.

20.

Sakai

S.I.

, Watanabe

, Honda

, Takatsuki

, Aoki

, Futamatsu

, Shiozaki

2001. Combustion of brominated flame retardants and behaviour of its byproducts. Chemosphere, 42:519.

21.

Samara

, Gullett

B.K.

, Harrison

R.O.

, Chu

, Clark

G.C.

2009. Determination of relative assay response factors for toxic chlorinated and brominated dioxins/furans using an enzyme immunoassay (EIA) and a chemically-activated luciferase gene expression cell bioassay (CALUX) Environ. Int., 35:588.

22.

Sinkkonen

, Lahtiperä

, Vattulainen

, Takhistov

V.V.

, Viktorovskii

I.V.

, Utsal

V.A.

, Paasivirta

2003. Analyses of known and new types of polyhalogenated aromatic substances in oven ash from recycled aluminium production. Chemosphere, 52:761.

23.

Sjödin

, Carlsson

, Thuresson

, Sjölin

, Bergman

, Ostman

2001. Flame retardants in indoor air at an electronics recycling plant and at other work environments. Environ. Sci. Technol., 35:448.

24.

Söderström

, Marklund

2000. PXDD and PXDF from combustion of bromoflameretardent containing MSW. Organohalogen Compd., 47:225.

25.

Söderström

, Marklund

2002. PBCDD and PBCDF from incineration of waste containing brominated flame retardants. Environ. Sci. Technol., 36:1959.

26.

Taiwan

EPA

. 1997. Waste incinerator dioxin control and emission standards. Taipei, Taiwan.

27.

Taiwan

EPA

. 2004. Laboratory quality assurance and quality control protocols of the Taiwan. NIEA PA101. Taipei, Taiwan.

28.

USEPA. 1996. Sampling method for polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans emissions from stationary sources. Method 23A. Washington, DC.

29.

USEPA. 1999a. Chlorinated biphenyl congeners in water soil, sediment, and tissue by HRGC/HRMS. Method 1668A. Washington, DC.

30.

USEPA. 1999b. Determination of polychlorinated, polybrominated and brominated/chlorinated dibenzo-p-dioxins and dibenzofurans in ambient air. Method TO-9A. Washington, DC.

31.

USEPA. 2001. Determination of particulate emission from stationary sources. Method 5. Washington, DC.

32.

USEPA. 2007. Brominated diphenyl ethers in water soil, sediment and tissue by HRGC/HRMS. Method 1614. Washington, DC.

33.

Van den Berg

, Birnbaum

L.S.

, Denison

, De Vito

, Farland

, Feeley

, Fiedler

, Hakansson

, Hanberg

, Haws

, Rose

, Safe

, Schrenk

, Tohyama

, Tritscher

, Tuomisto

, Tysklind

, Walker

, Peterson

R.E.

2006. The 2005 World Health Organization reevaluation of human and mammalian toxic equivalency factors for dioxins and dioxin-like compounds. Toxicol. Sci., 93:223.

34.

Wang

L.C.

, Chang-Chien

G.P.

2007. Characterizing the emissions of polybrominated dibenzo-p-dioxins and dibenzofurans from municipal and industrial waste incinerators. Environ. Sci. Technol., 41:1156.

35.

Wang

L.C.

, His

H.C.

, Wang

Y.F.

, Lin

S.L.

, Chang-Chien

G.P.

2010a. Distribution of polybrominated diphenyl ethers (PBDEs) and polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) in municipal solid waste incinerators. Environ. Pollut., 158:1595.

36.

Wang

L.C.

, Tsai

C.H.

, Chang-Chien

G. P.

, Hung

C.H.

2008. Characterization of polybrominated dibenzo-p-dioxins and dibenzofurans in different atmospheric environments. Environ. Sci. Technol., 42:75.

37.

Wang

L.C.

, Wang

Y.F.

, His

H.C.

, Chang-Chien

G.P.

2010b. Characterizing the emissions of polybrominated diphenyl ethers (PBDEs) and polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) from metallurgical processes. Environ. Sci. Technol., 44:1240.

38.

Wang

M.S.

, Chen

S.J.

, Huang

K.L.

, Lai

Y.C.

, Chang-Chien

G.P.

, Lin

W.Y.

2010c. Determination of levels of persistent organic pollutants (PCDD/Fs, PBDD/Fs, PBDEs, PCBs, and PBBs) in atmosphere near a municipal solid waste incinerator. Chemosphere, 80:1220.

39.

Wang

M.S.

, Wang

L.C.

, Chang-Chien

G.P.

, Lin

L.F.

2005. Characterization of polychlorinated dibenzo-p-dioxins and dibenzofurans in the stack flue gas of a municipal solid waste incinerator, in the ambient air, and in the Banyan leaf. Aerosol Air Qual. Res., 5:171.

40.

Weber

L.W.

, Greim

1997. The toxicity of brominated and mixed-halogenated dibenzo-p-dioxins and dibenzofurans: an overview. J. Toxicol. Environ. Health, 50:195.

41.

Weber

, Kuch

2003. Relevance of BFRs and thermal conditions on the formation pathways of brominated and brominated-chlorinated dibenzodioxins and dibenzofurans. Environ. Int., 29:699.

42.

Wilken

, Beyer

, Jager

1990. Generation of brominated dioxins and furans in a municipal waste incinerator (MWI): results of a case study. Organohalogen Compd., 2:377.

43.

World Health Organization (WHO). 1994. Polybrominated diphenylethers. Enrion. Health Criter., 162. Geneva, Switzerland-WHO www.inchem.org/documents/ehc/ehc/ehc162.htm.

44.

World Health Organization (WHO). 1998. Polybrominated dibenzo-p-dioxins and dibenzofurans. Enrion. Health Criter., 205. Geneva, Switzerland-WHO www.inchem.org/documents/ehc/ehc/ehc205.htm.

45.

Wyrzykowska

, Gullett

B.K.

, Tabor

, Touati

2008. Levels of brominated diphenylether, dibenzo-p-dioxin, and dibenzofuran in flue gases of a municipal waste combustor. Organohalogen Compd., 70:62.