Toolkit for Identification and Quantification of Releases of Dioxins, Furans and Other Unintentional POPs
PART III Example Inventories
Example Inventory 11 Source Group 10 Contaminated Sites and Hot Spots
This example inventory contains a series of practical examples and best practice cases of PCDD/PCDF inventories for the most relevant source categories, including, where available, quantitative PCDD/PCDF data.
Experience from China, Germany, Sweden and the USA proves that chlor-alkali processes can generate large quantities of PCDD/PCDF (Weber et al. 2008a,b). Limited data are available on the total PCDD/PCDF production and release in chlor-alkali plants, but a detailed inventory has been prepared and published for Rheinfelden in Germany (Otto et al 2006). Griesheim Elektron operated a chlor-alkali plant at this site starting with 1898 for 87 years. Toxic residues of the chlor-alkali process together with other industrial waste were disposed of in small gravel pits in the vicinity of the plant without safety measures. In 1989, widespread PCDD/PCDF contamination was discovered in soils (Otto et al. 2006). The analysis demonstrated that PCDF contamination was dominant, and samples revealed peak concentrations of 26,000 ng TEQ/kg in topsoil and up to 3,800,000 ng TEQ/kg in deep soil, comprising mainly of historic sludge deposits.
The approach for the inventory at Rheinfelden included:
A PCDD/PCDF inventory was established based on monitoring data and related assessments, followed by remediation and containment of deposits and contaminated soils. The total amount of PCDD/PCDF residues deposited from the chlor-alkali plant was estimated at 8.5 kg I-TEQ (Otto et al. 2006). Furthermore, between 1970 and 1986 the factory also produced PCP and PCP-Na, and the residues associated with this production were estimated to contain an additional 7.7 kg I-TEQ (with a total 7 tons of PCDD/PCDF), thus a total PCDD/PCDF contamination of 16.2 kg I-TEQ (Otto et al. 2006).
The only PCDD/PCDF inventory yet established for a Leblanc factory is at Lampertheim, Germany, for a plant which operated between 1840 and 1893. In the late 1980s, high levels of arsenic and lead were detected in soil in the vicinity of the site. Subsequent investigations in the 1990s also revealed high levels of PCDF (and PCDD to a lesser extent) (Balzer et al. 2007, 2008).
The assessment included historical investigation and archive research to retrieve information on the production site, as well as technical and scientific literature review on the Leblanc process and associated processes. Based on these investigations, a detailed soil analysis was undertaken, with more than 600 soil cores analysed for a range of organic and inorganic contaminants. Approximately 500 samples were also analysed for PCDD/PCDF, confirming that the entire surface and subsurface soil was highly contaminated with PCDD/PCDF and heavy metals. A PCDD/PCDF inventory was thus established based on the levels measured in samples and the volumes of deposited residues and contaminated soils. The total amount of PCDD/PCDF in soils and deposits was of 1-10 kg TEQ, while the total arsenic and lead contamination was of 12- 80 tons and 50-300 tons respectively (Balzer et al. 2007).
Since a range of chemical processes were employed in Leblanc plants, the individual steps and processes were evaluated with respect to their PCDD/PCDF formation potential. Four distinct operational steps with a high PCDD/PCDF formation potential have been identified for the Lampertheim factory (Balzer et al. 2008):
A European survey of Leblanc factories revealed that at least 70 to 100 factories were operated during the 19th century mainly in Great Britain, France and Germany (Balzer et al. 2008). According to historical records, 413,000 tons of sal soda were produced in 1865 via the Leblanc process, with the main producers located in the United Kingdom (234,000 tons), France (108,000 tons) and Germany (66,000 tons). An inventory of former Leblanc sites has only been made in Germany, where 15 locations have been identified (Balzer et al. 2008). At least 30 Leblanc factories have also been operated in France, while in the United Kingdom approximately 30 to 40 Leblanc factories were operational during the mid-19th century.
The Finnish Environment Institute has compiled an inventory and risk assessment of PCDD/PCDF contaminated sediments from releases of a polychlorophenol (PxCP) wood preservative Ky-5. Ky-5 was manufactured in the upper reaches of the Kymijoki river in South-Eastern Finland between 1940 and 1984 (Verta et al. 2009).
The product consisted mainly of 2,3,4,6-tetrachlorophenol (83%), pentachlorophenol (8%) and 2,4,6,-trichlorophenol (6%). PCDD/PCDF, especially the higher chlorinated dibenzofurans, were major impurities in the product and in residues. The company discharged residues into the river system resulting in highly contaminated sediments with a maximum PCDD/PCDF concentration above 400,000 µg/kg (Verta et al. 2009 ).
Sediment cores from 220 sites were collected between 1997 and 2003. PCDD/PCDF were analysed from sub-samples of ten sediment cores, 35 surface sediment samples, 15 locations in the river and ten coastal sites from the Gulf of Finland (Isosaari et al. 2002, Verta et al. 2009).
Figure III.11.1 shows the concentration of PCDD/PCDFs in sediments. The total volume of contaminated sediments was estimated to be 5×106 m³ and the hot spot volume amounted to approximately 90,000 m³ of sediments with extremely high concentrations (max. 292,000 µg/kg or 1,060 µg I-TEQ/ kg d.w.). These were located immediately downstream from the factory.
The total amount of Ky-5 chlorphenol-derived PCDD/PCDF was estimated to be approximately 5,960 kg (17.3 kg I-TEQ) in the river sediments and 1,770 kg (12.4 kg I-TEQ) in the Gulf of Finland (Fig. III.11.1; Verta et al. 2009). In addition to the PCDD/PCDF inventory, the Finnish Environment Institute calculated the yearly PCDD/PCDF fluxes within the river and into the Gulf of Finland and projections for the next decades (Verta et al. 2009).
In some cases, lindane production has recycled (part of) HCH waste isomers due to economic reasons and to reduce dumping of HCH waste. In Germany, HCH waste isomers were recycled between 1953 and 1984 by thermal decomposition (250ºC-260ºC) to produce technical tri/tetrachlorbenzene (Jürgens and Roth 1989). In this reaction step, a so-called ‘decomposer residue’ was produced, containing 1.4 to 2.7% PCDD/PCDF with I-TEQ in the high ppm range (90 to 230 ppm) (Jürgens and Roth 1989, Vijgen et al. 2011). The final residues from the HCH recycling process were highly contaminated with PCDD/PCDF and resulted in the closure of the factory in 1984 (Jürgens and Roth 1989, Vijgen et al. 2011, Götz et al. 2012).
The total amount of PCDD/PCDF landfilled from registered waste residues generated by thermal HCH decomposition was estimated between 53 and 102 tons for sum PCDD/PCDF, and between 333 and 854 kg I-TEQ contained in approximately 3,700 tons of wastes from HCH recycling (Götz et al. 2012). In addition, approximately 2,500 tons of un-recycled HCH waste isomers and 10,000 tons of other organochlorine wastes with lower PCDD/PCDF content were deposited in at least eight landfills (Bürgerschaft Hamburg 1985, University Bayreuth 1995). A detailed inventory of contaminated sites and deposits has been developed for the city of Hamburg and other landfills. PCDD/PCDF fingerprinting has been used for assigning contamination and proving that a site was contaminated with PCDD/PCDF (Sievers and Friesel 1989).
Recycling of HCH waste has been undertaken by several other lindane producers (Vijgen et al. 2011) and may still be in practice today in two former lindane factories in India (Jit et al. 2010). A similar approach to establishing an inventory might be useful for other sites.
Table III.11.1 PCDD/PCDF and other chlorinated organohalogen compounds in soil from storage, spills and leaks at the production site*
|Contaminant||Amount of organohalogens|
|Total PCDD/PCDF (TEQ)||6 kg|
|HCH isomers||262 tons|
|EOX (calculated to Cl)||663 tons|
* contained in a total volume of 559,000 m³ soil
While the levels of PCDD/PCDF in some products (e.g. pesticides) have been monitored, the levels in production residues are often unknown. To assess occupational safety during the excavation of the Bonfol chemical landfill in Switzerland, a PCDD/PCDF inventory of the deposited waste was compiled. The Basel Chemical Industry (BCI) has produced and used a range of chlorinated aromatic compounds not known to be highly contaminated with PCDD/PCDF or precursors (e.g. 2,4-D, 2,4,5-T or PCP). Between 1961 and 1976, the industry disposed of 114,000 tons of chemical wastes in the Bonfol landfill, an old clay quarry. Because the landfill contaminated groundwater, BCI was forced to fully remediate the site by excavating and incinerating chemical wastes.
For the inventory, the chemicals listed by the German Environmental Agency (UBA) as containing or potentially containing PCDD/PCDF were used as one information source (UBA 1985). This list was supplemented by additional literature on substances containing PCDD/PCDF and PCB (Forter 2005, 2006) including:
It was established that at least 38 substances produced and used from the 1950s to 1970s by BCI contained, or potentially contained PCDD/PCDF. These substances were used in the production of several hundred final products. PCDD/PCDF wastes were estimated for four of these products: the production of trichlorophenol by Roche and the production of dioxazin pigments and paints, Mitin LA and triclosan by Geigy or Ciba-Geigy (Forter 2005, 2006) (Table III.11.2).
The majority of PCDD/PCDF and PCB impurities from educts and those formed during the production of trichlorophenol, triclosan, Mitin LA and Oxazin/Dioxazin pigments and paints ultimately ended up, by a process of filtration and distillation of the chlorinated solvents, in the residues and were ultimately disposed of at the Bonfol chemical landfill between 1965 and 1975. Considering the PCDD/PCDF quantities resulting from these four production processes, and taking into account that BCI was a heavy user of chlorinated solvents, it was shown that total TEQ levels of several tens of kilogram were present in the Bonfol landfill (Forter 2005, 2006). The total quantity of PCDD/PCDF and PCB was estimated to be as much as one ton (Forter 2005, 2006).
Table III.11.2 Order of magnitude estimates of the PCDD/PCDF wastes from BCI production during 1964-1975
|Period of time||Estimated total PCDD/PCDFamount (kg)||Estimated PCDD/PCDF I-TEQ (kg)|
|Trichlorophenol||End 1960s||Unknown||> 0.1|
|Oxazin & Dioxazin
pigments and dyes
|1965–1975||Several 100||1 to several kg|
|Triclosan||1966–1975||Several 10 to several 100||0.1 to 1|
|Mitin LA||1974–1975||Unknown||0.01 to several 0.01|
|Total||Several 100||1 to several kg|
Wastes from the production of chlorinated solvents at the former Kalush Chemical and Metallurgical Industrial Complex were buried near Kalush City, Ukraine. The solvents produced included carbon tetrachloride, tetrachloroethene and dichloroethene (ethylene dichloride EDC) for PVC manufacturing. Solvent production started in 1973 with an estimated production capacity of approximately 30,000 tons per year. Approximately 540 tons of hazardous “HCB waste” with unintentionally produced HCB as a primary contaminant was produced annually, suggesting an emission factor of 18 kg “HCB waste”/t solvent produced for this factory (Weber et al. 2011a,b). The total amount of “HCB waste” deposited was estimated to be approximately 11,000 tons (UNEP, OCHA and EU Commission 2010). Since the HCB content of the waste is around 20%, the total amount of HCB deposited at this site can be estimated to be around 2,200 tons (Jacoff et al. 1986). Sampling of “HCB waste” also found PeCB at levels approximately an order of magnitude lower than HCB. The total quantity of PeCB waste contained in the total 11,000 tons of “HCB waste” can be estimated to be approximately 200 tons.
Other cases of stored or deposited HCB waste show that the inventories for solvent production facilities which did not have adequate destruction capacity in the 1950s to 1990s are of the same order of magnitude:
In the production of lindane (gamma-HCH), approximately 85% of the waste isomers are formed in the chlorination step of benzene as unintentionally formed POPs (Vijgen et al. 2011). The active gamma-isomer was commonly separated, and the remaining 85 to 90% waste isomers, consisting mainly of alpha-HCH and some beta, delta and epsilon-HCH, were dumped. A global inventory of these wastes was compiled based on information collected for over 20 years of production, including HCH production capacities and estimated amounts of wastes generated (Vijgen et al. 2011). 1.6 – 1.9 million tons of disposed HCH waste were thus estimated in the former producing countries (Albania, Austria, Argentina, Brazil, China, Croatia, Czech Republic, France, Germany (including former German Democratic Republic), Hungary, India, Italy, Japan, Macedonia (former Yugoslavia), Nigeria, Poland, Romania, Slovakia, South Africa, Spain, Switzerland, Turkey, The Netherlands, UK, USA, and the former USSR). This inventory is considered to underestimate the scale of the problem because of the incomplete reporting and the likely existence of unidentified productions sites and waste deposits.
In a second inventory approach, the total quantity of HCH waste was estimated by using the proportion of waste isomers produced per tonne of lindane used (Vijgen et al. 2011). Global historical lindane use for agricultural purposes was estimated to have been between 1950 and 2000 of 450,000 t, with the largest share (63%) in Europe (Vijgen et al. 2011). Additional use of lindane on livestock, in forestry, in human pharmaceuticals and for other purposes has also been considered and is estimated to add another 150,000 t (Vijgen 2006a,b), bringing the total global figure to 600,000 t. According to Bodenstein (1972), the total HCH isomer waste was about 8 tons per ton of Lindane produced. Other experts have estimated about 10 tons per ton of Lindane produced (Krum 1982) and 10-12 tons per ton of Lindane produced (Treger 2004). Using the range of these approximations (8 to 12 tons), the total global amount of HCH waste is estimated between 4.8 and 7.2 million tons, constituting the largest international POPs stockpile.
The total amount of PCDD/PCDF releases from former pesticide use and related contaminated areas has been investigated and assessed in Japan (Masunaga et al. 2001, Seike et al. 2007, Weber and Masunaga 2005). Two herbicides, PCP and CNP, applied from 1950s to 1980s, contained elevated concentrations of PCDD/PCDF. In the case of CNP, the average PCDD/PCDF content in formulations produced pre-1982 was estimated to be 6 g/kg and 3.60 mg TEQ/kg active ingredient (N= 39 samples). After 1982 the PCDD/PCDF content of CNP decreased to 0.71 g/kg and 0.022 mg WHO-TEQ/kg active ingredient (N= 23 samples) (Masunaga et al. 2001, Seike et al. 2003). High PCDD/PCDF levels were found in PCP produced in the early 1960s, but also for some PCP produced at the end of the 1970s. The average dioxin content in PCP (N= 14 samples) was 3.3 g PCDD/PCDF per kilogram and 1.5 mg TEQ/kg active ingredient (Masunaga et al. 2001, Seike et al. 2003). Other pesticide formulations contained comparatively low concentrations of PCDD/PCDF (Masunaga et al. 2001).
The total dioxin releases from the application of pesticides on rice fields and agricultural areas in Japan during 1955-1995 was estimated based on the arithmetic average concentration of PCDD/PCDF in historical pesticides and the amount of pesticides used. The total emission from PCP use was estimated to be 540 tons of PCDD/PCDF or 250 kg TEQ. The total emission from CNP use was estimated to be 380 tons of PCDD/PCDF or 210 kg TEQ (Figure III.11.2; Weber et al. 2008a,b). These loads contribute a large proportion of today’s PCDD/PCDF contamination in Japanese soil and sediments (Masunaga 2004, Sakai et al. 2008). The PCDD/PCDF pattern in human milk samples from Japan has even nowadays a significant input from former PCP use (Tawara et al. 2006, Weber et al. 2008a,b).
A historical PCDD/PCDF inventory application and PCDD/PCDF transport to rivers and ocean sediments has been established for the Tokyo Bay basin (Masunaga 2004, Weber and Masunaga 2005). For this task, the dioxin load of the Tokyo Bay basin was estimated from the annual quantities of agrochemical shipments to Tokyo, Saitama, Chiba and Kanagawa prefectures, the % area belonging to the basin, and the dioxin contamination of the agrochemicals. The PCDD/PCDF load of the Tokyo Bay basin due to PCP use was estimated to be approximately 31,000 kg PCDD/PCDFs and 14 kg TEQ. The contribution from CNP was estimated to be 9,300 kg PCDD/PCDF and 5 kg TEQ. The total amount of PCDD/PCDFs deposited in sediments was estimated from sediment core data (Masunaga 2004). A comparison between the total PCDD/PCDF emissions and the sediment load in Tokyo Bay shows that only a few % of PCDD/PCDF applied to paddy fields as agrochemical impurities have been deposited in the Tokyo Bay. Due to the persistency of these compounds, the remaining PCDD/PCDF still exist in terrestrial soil and river sediments, representing an input source into the future. According to the concentration of PCDD/PCDF in Tokyo Bay sediments, the flux from PCP use remained constant over the past 20 years. This indicates that PCDD/PCDF transport processes in the environment may last for decades and most likely centuries.
The inventory of PCB contaminated sites in Belarus included:
1) PCB-containing equipment
The first inventory of PCB-containing equipment in Belarus was developed in 2004. More than 2,000 enterprises were covered in the inventory process. The methodology is described in Kukharchyk and Kakareka (2008). About 40 companies were identified as owners of PCB-containing transformers and 750 companies as owners of PCB-containing capacitors (Government of Belarus 2006). All of these sites were treated as potential hot spots. A database was created, containing detailed information on the facilities and the PCB-containing equipment, including facility name and address, types and number of equipment, trademarks, volumes of PCB, dates of manufacture, condition of the equipment, levels of operation, descriptions of installations or storage locations. The total volume of PCB in PCB-containing equipment in Belarus was estimated at 1,500 tons. 55% of the total amount of PCB is contained in power transformers and 44% in power capacitors. A substantial part of PCB-containing equipment has been removed from service long time ago: around 25% of capacitors and 9% of transformers with a total volume of 230 tons PCB have been taken out of operation. In the past, no measures have been taken to ensure storing of PCB-containing equipment in an environmentally sound manner. The condition of power capacitors and transformers was evaluated in many cases as unsatisfactory, due to the destruction of their frames.
The sites where PCB leakages occur were also revealed. Special attention was given to open sites where the probability of PCB leakage was very high. Documented accidents were also taken into account. Special field investigations of selected sites were organized with the aim to indicate damage characteristics, features of PCB leakages, etc.
Based on the results of the investigation, PCB release factors were developed: for PCB-containing transformers – 0.3 kg/t dielectric fluid, for capacitors – 2 kg/t (EMEP/EEA 2009). It was found that approximately 1.5 tons of PCB are annually discharged into the environment from leaking power transformers and capacitors.
The potential discharges of PCDD/PCDF were calculated taking into account the total PCB leakage from PCB-containing equipment and the content of PCDD/PCDF in low chlorinated dielectrics fluids (in capacitors) and high chlorinated fluids (in transformers).
The PCB database is updated every year, including information on the total number of PCB-containing equipment and equipment taken out of service (Government of Belarus 2006).
Several projects investigating PCB-contaminated sites and soil pollution were implemented during 2005-2011 in Belarus, including on-site inspection, identification of damaged equipment, detection of leakages, soil sampling and analysis. More than 80 open sites and several dozens of closed sites where PCB-containing equipment is still in operation or in storage were investigated. As a result, the list of PCB contaminated sites was developed including facility name, address, location, type of sources, and PCB content in soil. About 60 sites were found to have polluted soil. PCB content in soil is found at levels up to milligrams or sometime grams per kilogram (Kukharchyk et al. 2008, 2011). The highest concentrations of PCB (up to 105 g/kg) were found in the soil near destroyed capacitors and transformers. In most cases, PCB content in soils was heterogeneous; usually there are several small hot spots within one site. The size of hot spots is different; most of them are less than 1 m2, but sometimes reach up to 50 m2. The largest polluted site has an area of more than 1000 m2 and included several individual hot spots. Generally, the number of hot spots and their size depends on the area where PCB-containing equipment is installed or stored, as well as on the quantity of PCB-containing equipment, the time of its operation or storage, the share of damaged equipment, incidents such as explosion of capacitors and PCB spraying. The highest level of pollution was found in the upper soils (top 10 cm). However, in some cases, high levels of PCB pollution were also found at depths of 1 m and more.
2) PCB-containing paint/varnish production
A significant source of PCB release into the environment was the use for paint and varnish production (Kukharchyk et al. 2008). Historical data on the annual volume of PCB in use at the Lakokraska factory in the city of Lida, Belarus were collected. It was established that during 1968-1998, about 5,000 tons of Sovol was used. The paint/varnish production process was analysed and possible ways of Sovol discharges into environment were assessed. Taking into account technological discharges of raw material, it was established that approximately 130 tons of Sovol were released into the environment (mainly in soil) on the site of the plant.
PCB content in soil was found at levels up to 96.6 mg/kg. The spatial distribution of PCB is homogenous in comparison with the places where PCB-containing equipment is installed or stored. Penta- and hexachlorobiphenyls are dominating among PCB compounds, with 53% and 28% respectively, clearly indicating that the source of PCB discharge is Sovol.
The Swiss Federal Office for Environment in cooperation with the Swiss EMPA developed a methodology for inventorying PCB-impacted water bodies and classification according to the dioxin-like PCB content in fish. The inventory approach includes tracking of PCB point sources resulting in levels of dioxin-like PCB in fish above the regulation limits for fish consumption.
Monitoring data of 1,300 fish samples analysed over two decades were evaluated. For three rivers, dioxin-like toxicity levels above legislation limits were found (BAFU 2010). An inventory of impacted river sections was then established (Zennegg et al. 2010). Fish were contaminated within sections of 20 to 40 km of river. In a second step, river sections with elevated PCB levels in fish were screened for point sources by passive sampling.
A former disposal site (La Pila) was identified as the point source responsible for PCB contamination in the Saane river. The landfill was used for domestic and industrial waste (from 1952 to 1975). The amount of PCB was estimated to be more than 20 tons within approximately 195,000 m³ waste (Zennegg et al. 2010). Flooding events and rain washed out these PCB and enabled their migration into the river.
On the basis of PCB levels measured in fish, water bodies were classified into three categories (Zennegg et al. 2010): the first category was defined as water bodies with PCB background contamination corresponding to levels below 4 pg WHO-TEQ/g fw (50% of the maximum level of 8 pg WHO-TEQ/g fw); the second category contains water bodies with diffuse to higher PCB load and levels of 4 to 8 pg WHO-TEQ/g fw in fish; the third category was defined as water bodies with high PCB contamination, where most fish species exceed the permitted maximum level.
The pulp and paper sludge from bleaching with elemental chlorine has been highly contaminated with PCDD/PCDF and other chlorinated compounds. The application of such sludges on land or through their dumping have resulted in hot spots or contaminated land. Paper sludge residues from a German paper mill were deposited on an area of 7,000 m2 during the 1970's (Rotard et al. 1990). The area was developed into a residential area in the 1980s. For the assessment, the area was divided into 12 sectors of about 500 to 1,000 square meters each. From each sector, 20 to 35 soil samples were taken from a depth of 0.3 m, then mixed thoroughly to give a representative sector sample. Some samples were taken at a depth of 4 meters by ram core sampling. The area was found interspersed with paper sludge lumps on the surface and at depths of 1.8 meters. Soil samples showed contamination of up to 149 ng/kg I-TEQ. The sludge lumps contained PCDD/PCDF levels between 573 to 5,165 ng/kg I-TEQ (Rotard et al. 1990).
If incinerators are operated according to BAT and the wastes managed according to BEP, PCDD/PCDF contaminated sites or hot spots should not be generated except for the deposit of fly ash and air pollution control residues which can still have relatively high levels of contamination. Experience has shown that incinerators which are not well-operated and controlled can produce high levels of PCDD/PCDF emissions to all media and result in contaminated sites or hot spots.
Emissions from a chemical waste incinerator at the Coalite Chemicals plant in Bolsover (UK), which was used for the incineration of chlorinated phenol wastes, resulted in elevated PCDD/PCDF levels in cow’s milk from the surrounding area (Holmes et al. 1994, 1998) and other foodstuff including game birds (Malisch et al. 1999). This case demonstrates that hazardous waste incinerators that process high proportions of products from the organochlorine industry, especially PCDD/PCDF precursors (PCB, chlorophenols, chlorobenzenes and other chlorinated aromatics), can result in high emissions of PCDD/PCDFs with considerable impacts on the local environment (Holmes et al. 1994, 1998). The Coalite plant also generated high levels of contamination in river sediments. Investigations by the UK National Rivers Authority found that the river sediments contained 20,269,000 ng/kg PCDD/PCDF (45,300 ng/kg TEQ) immediately downstream of the company's outfall, while the upstream levels were of only 2,030 ng/kg (9 ng/kg TEQ). The impact of the site was discernable 11 kilometres downstream on the Rother river, where sediments contained 110,000 ng/kg PCDD/PCDF (ENDS 1994).
Further, the largest release vector for PCDD/PCDF from BAT/BEP incinerators are residues and ashes from flue gas treatment, which can contaminate the environment if they are not appropriately managed. One example is the Byker municipal waste incinerator in Newcastle (UK) where ashes (generally a mixture of fly and bottom ash) were used to construct footpaths and added to the garden soils, resulting in elevated PCDD/PCDF levels in food (eggs and vegetables) (Pless-Mulloli et al. 2001, Watson 2001).
The low-tech recycling of e-waste in China, India, and many other Asian and African countries has resulted in contaminated sites from these activities. Such low-tech e-waste recycling sites exist predominantly in developing and transition countries and PCDD/PCDF emissions from the open burning of PVC and partly PCB-containing e-waste can be very high. A wide range of PCDD/PCDF and other dioxin-like compounds including brominated and mixed halogenated dioxins, furans, biphenyls and other mixed brominated-chlorinated aromatics have been detected at open burning sites in Guiju, China (Yu et al. 2008, Zennegg et al. 2009, Leung et al. 2007, Li et al. 2007, Wong et al. 2007). Preliminary inventory investigations of PCDD/PCDF and dioxin-like compounds revealed contamination levels of soils above international limit values (Yu et al. 2008). A combination of instrumental- and bioassay-based assessments was used for adequately estimating dioxin-like toxicity. Levels up to 100 µg TEQ/kg soil have been measured at open burning sites (Yu et al. 2008), with brominated-chlorinated PXDD/PXDF as a main contributor (Zennegg et al. 2009). In the Guiyu area, where e-waste burning has been practiced for more then a decade, the contamination levels in the soils are in the kg TEQ range. These sites are also highly contaminated with heavy metals resulting in ground water pollution (Chan et al. 2007). All these aspects need to be considered when developing pollutant inventories for these sites.
On December 22, 1992, a fire destroyed a warehouse containing cable drums at JSC "Irkutskcable" (Shelekhov, Irkutsk region). The fire destroyed an area of 20,000 m2 around the ignition point, including adjacent warehouses containing plastic resin and paper, as well as a drying and impregnation shop. The fire lasted for 10 days, with the height of the smoke column reaching 100 m in the early stage. According to draft assessments, 600 tons of PVC plastics and 100 tons of PVC film were destroyed in the fire (Kiselev and Khudolej 1997). For technical reasons, fire masks were not used. Acute poisoning has been confirmed for 69 firefighters; 43 of them were recognized as disabled. As a result of incomplete combustion, PCDD/PCDF were released. The soot formed during the decomposition of PVC cables contained up to 200 ng/g PCDD/PCDF. It should be noted, however, that the uncertainty of the results is high due to the limited volume of samples analyzed.
The Elbe river has been impacted during almost a century by POPs (PCDD/PCDF, HCHs, DDT etc.) and other pollutants such as Organo-tin from industrial discharges, including organochlorine production and other industries using chlorine in the Bitterfeld region of Germany. The sediments and floodplains were shown to be contaminated with PCDD/PCDF approximately 350 km downstream - as far as Hamburg and even the North Sea (Götz et al. 2007). The sources of pollution have been assessed and an inventory developed, showing that approximately 60 km2 of lowland area downstream of the Spittelwasser creek are heavily contaminated by PCDD/PCDF, HCH and DDT. The pollutant reservoir includes 20,000 m³ of highly contaminated PCDD/PCDF sediments (Förstner and Salomonis 2010). PCDD/PCDF levels in the floodplains soils reached up to 2,100 ng I-TEQ/kg. In addition to inventory activities, the options for the different zones along the river (river shore, inner dyke, outer dyke) have been assessed taking into account the EU food limits for managing cattle and feedstuff in the floodplains (Schulz et al. 2005, Kamphues et al. 2011). While milk from grazing cows and meat from permanent grazing animals is above the EU food limits and can not be produced, certain techniques have been developed for harvesting the grass/hay so that it can be used for feeding. Recommendations for farmers using contaminated grassland for feed and food production were developed (Kamphues et al. 2011)) and can be regarded as a pilot case for inventory and managing other floodplanes contaminated with PCDD/PCDF or PCB and the related pollutant reservoirs upstream (Förstner and Salomon 2010).
More than 500,000 tons of mixed industrial wastes were illegally dumped into a 30 ha gravel pit site on Teshima Island in Japan from 1970 until 1988 (Takeda 2007). Major components included shredder residues from end-of-life vehicles and electric appliances, paper mill sludges, slags, dewatered industrial sludge, incineration residues. A detailed assessment and inventory of the wastes, surrounding soil, groundwater and surface water was conducted. It revealed that wastes and soil were contaminated with notable quantities of heavy metals and chlorinated organic compounds, including an estimated 1.5 kg TEQ PCDD/PCDF (Takeda 2007). Water soluble pollutants contaminated groundwater with a risk of releases to the sea and shore. A remediation plan was established to excavate the waste and the contaminated soil and transport this material to a neighbouring island where an incinerator and a melting plant was built (Takeda 2007). The cost of the remediation work was estimated at 428 million US$, while the operation of the dumpsite had generated approximately 3 million US$ revenue (Takeda 2007).
The example at the Love Canal site in the Niagara County also shows successful site remediation and cleanup procedure. The site encompasses a hazardous waste landfill where chemical waste products were disposed of from 1942 to 1952 by the Hooker Electrochemical Company. It first came into national prominence in the late 1970s, when it was discovered that contaminated leachate had migrated to the surface of the canal and to nearby residential basements. Contaminants also migrated to nearby creeks via the sewage system. Scientific studies did not conclusively prove that these chemicals were responsible for residents' illnesses, and scientists were divided on the issue, even though eleven known or suspected carcinogens had been identified, one of the most prevalent being benzene. Polychlorinated dibenzodioxins were also found, with levels measured in water samples of 53 ppb.
In October 1978, containment measures were undertaken, including the construction of a tile drain and leachate collection system, placement of a clay cap over 16 acres of the canal, creation of an on-site leachate treatment facility and installation of a fence around the area. Approximately 1,000 families have been relocated from the area.
In 1984, 40 acres were covered by a synthetic liner and clay cap and surrounded by a barrier drainage system. A long-term monitoring study was implemented to evaluate the effectiveness of the leachate collection system and assess the contaminant migration in soil and groundwater. In September 2004, the EPA removed the Love Canal site from the National Priorities List (NPL). All cleanup work had been completed, and follow-up monitoring conducted over the past 15 years confirms that the cleanup goals have been reached. The site will continue to be monitored and remains eligible for cleanup work in the event that a change in site conditions should warrant such an action.
The discovery of toxic waste dumps such as the Love Canal led to the adoption of the Comprehensive Environmental Response Compensation and Liability Act (CERCLA) in the United States. CERCLA is commonly referred to as the "Superfund" because of the fund established to help the cleanup in residential locations. The Superfund cleanup process involves steps to assess sites, placing them on the National Priorities List (NPL), and establish and implement appropriate cleanup plans. Over the past years, tens of thousands of hazardous waste sites and other polluted sites were located and analyzed. Currently, 13,742 sites are listed, among which 1,723 sites belong to the NPL. The inventory contains 225 sites polluted by PCDD/PCDF, among which 210 NPL sites, and 488 sites polluted by PCB, including 431 NPL sites.
Several kaolin and ball clay deposits have been found to be contaminated with PCDD/PCDF in different regions in the word (Horii et al. 2011). The Dutch governmental institute RIKILT analysed 28 samples of “pregnancy clays” (20 from Africa and 8 bought in The Netherlands) for the presence of PCDD/PCDF as part of a first inventory of contaminated clays in some African countries (Uganda, Kenya, Tanzania, Nigeria, Mali, Ivory Coast and Zimbabwe). In some regions, such as Africa and South America, clay minerals and soils are consumed by pregnant women as a cure for morning sickness and possibly a source of minerals such as iron. Clay for this use is available for sale in many parts of the world. Consumption can be as high as 300 gram per day, but average daily intake seems to be around 30-80 gram (Hoogenboom et al. 2011). The study assessed whether the clays were contaminated and carried a potential risk for the newborns. Four of these samples showed relatively high levels of PCDD/PCDF: 66 ng TEQ/kg product (Mabele, Cameroon), 66 ng TEQ/kg product (Mabele, Democratic Republic of Congo), 75 ng TEQ/kg product (Kaolin, Côte d’Ivoire) and 103 ng TEQ/kg product (Mabele, country of origin unknown). In addition, a sample from Nigeria (Nzu) had a level of 24 ng TEQ/kg product and a sample from Cameroon (Mabele) had a level of 4.5 ng TEQ/kg product. Levels in other samples were much lower (Hoogenboom et al. 2011). Only PCDDs contributed to these TEQ levels, but the congener patterns were not the same for all clay samples.
The WHO/UNEP coordinated study on human milk included a number of African countries. The clay data have been compared with human milk data to evaluate whether the consumption of clay may add to the dioxin exposure. The highest PCDD/PCDF levels in African samples where observed in Côte d’Ivoire (11.1 pg TEQ/g fat) and the Democratic Republic of Congo (11.1 pg TEQ/g fat) whilst the other samples were in the range of 1.5 to 3.9 pg TEQ/g fat (Malisch et al. 2011). The PCDD/PCDF pattern of the clay and human milk samples, along with the relatively high levels measured in Congo and the Ivory Coast suggest that the use of clay during pregnancy contributes to these high PCDD/PCDF levels in human milk. Due to vulnerability to PCDD/PCDF in the fetal development phase and for the newborn, the use of contaminated clays should be prevented. Inventories of clays used for human consumption or as animal feed additive should be carried out as a matter of urgency.