Polychlorinated Biphenyls (PCBs) - World-Wide Contaminated Sites

TOCOEN REPORT

Polychlorinated Biphenyls (PCBs) - World-Wide Contaminated Sites

TOCOEN REPORT No. 173

Ivan Holoubek, Ph.D.

Kamenice 126/3, 625 00 Brno, Czech Republic Phone: +420 549 494 457, fax: +420 549 492 840

May 2000

Content:

Introduction

Production and import/export

Environmental fate

Global distribution of PCBs

Trends and environmental re-cycling of PCBs and other POPs

Environmental contamination

The case of Lake Baikal

The UK case

The "third pole" case (Himalayan lakes)

The Norway mosses case

The Greenland and Faroe Islands case

The Central and Eastern European countries case

Control of the industrial use of PCBs

Management of PCBs

Conclusions

References

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Polychlorinated Biphenyls (PCBs) - World-Wide Contaminated Sites 1.0

Content | Chapter 1 | 2 | 3 | 4 | 5 | 6 | 6.1 | 6.2 | 6.3 | 6.4 | 6.5 | 6.6 | 7 | 8 | 9 | 10

Introduction

Polychlorinated biphenyls (PCBs) share with DDT, the distinction of being among the first historically recognised persistent organic pollutants (POPs). Many of the same chemical and physical properties that had made them such desirable industrials, also made them one of the most widespread contaminants in the environment.

Until recently it was believed that there were no natural sources of PCBs. However, PCBs not associated with anthropogenic activities were identified in ash from the 1980 volcanic eruption of Mt. St. Helens, and subunits of PCBs have also been identified as components of two glycopeptides identified from Amylocolatopsis sp.

With respect to the different number of chlorine atoms and different positions they can have in the molecule, theoretically 209 compounds (isomers and congeners) are possible, but only about 130 of these are likely to occur in commercial products or mixtures (Safe, 1990).

Owing to appropriate physical-chemical properties (inert, insulting and lipophilic), PCBs were widely applied in industry, either in industry, either in closed systems (coolants and lubricants in transformers, dielectric fluids in capacitors, hydraulic fluids and heat-transfer media), or in open systems (plastificators, additives into carbonless copy paper, lubricants, inks, impregnating and paint agents, glue, wax, cement and plaster additives, lubrication of cast blocks, materials for dust separators, sealing liquids, flame retardants, immersion oils and pesticides. PCBs have been used since 1929 and are still in use today. The excellent properties of PCBs for industrial use also make it hazardous to the environment. Most of the PCBs were produced during the period 1950 to 1983. World-wide production has estimated to be 1.2 million tons. In 1982 it was estimated that approximately 31 % of PCBs been released to the general environment, 4 % had been destroyed, that 65 % was still in use or in storage, or deposited in landfills (Tanabe, 1988). The past widespread use of PCBs has resulted in their loss to the environment from evaporation and leakage from industrial applications, improper disposal and incineration methods, and from deliberate or accidental releases. The information on the breakdown of usage is very limited, making it very difficult to derive estimates for the historical and contemporary source term (Jones and de Voogt, 1999).

PCBs were firs detected in environmental samples in 1966 (Jensen, 1966). Subsequent research has shown PCBs to be ubiquitously present, both in human beings and the

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environment. This is due to their persistence in the environment, their ability to be distributed over large distances (even to areas where they have never been produced or used), their potential for bioaccumulation in organisms and biomagnification in the foodchain. Their harmful effects to man and the environment are well documented in a number of reviews (IARC, 1978; OECD, 1982; Lorenz and Neumeier, 1983; Kimbrough, 1987; IARC, 1987; DFG, 1988; ATSDR, 1993; WHO, 1993; Neumeir, 1998).

Unlike pesticides, such as DDT, PCBs has not been deliberately spread in the environment (Bremle, 1997). Large volumes of PCBs have been emitted by the open burning or incomplete incineration of waste, and by leakage from landfill sites and in the vicinity of factories. Another source is diffuse emission from such PCBs-containing materials as paints, coatings and plastics. The cities are sources of PCBs on regional scale (Halsall et al., 1995), due in particular to the out-gassing of PCBs from buildings. There has also been release of it due to accidents, such as in souls of transformer oil. The ban on PCBs in many countries did not lead to any immediate decrease of it in the environment. Rather, PCB-containing materials that were replaced often ended up on municipal landfills.

Over the past three decades, PCB control actions have been developed and implemented in most industrialised countries. Through both voluntary action by industry and government regulation, PCB production and the manufacture of PCB-containing equipment has ceased, and the continuing uses of PCB equipment are being phased out in most of these countries. As a result, PCB levels have gradually declined some industrial areas. However, PCB concentrations have not declined in remote areas and are unlikely to decline in the near future (Tanabe, 1988).

● PCB mobility and dispersion throughout the global environment; ● The safe management of existing PCBs and PCB-equipment including

decommissioning of PCBs, handling and storage; and ● The destruction of PCB wastes.



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Content | Chapter 1 | 2 | 3 | 4 | 5 | 6 | 6.1 | 6.2 | 6.3 | 6.4 | 6.5 | 6.6 | 7 | 8 | 9 | 10

Production and import/export

Production began in 1929. Monsanto Chemical Company manufactured PCBs in U.S. two plants: Anniston, Alabama (closed 1970) and Sauget, Illinois (closed 1977). Processes used by other manufacturers (e.g. in Europe) were probably quite similar.

Roughly 1.2 million metric tons of PCBs were produced world-wide between 1929 and 1977 (WHO, 1993). Of this total, more than half (635 000 tons) was produced in North America (CCREM, 1986). West Germany has also produced significant quantities of PCBs, possibly in the order of 200 000 to 300 000 tons. PCBs have also been produced in several other European countries, including France, Italy and Spain. The commercial production of PCBs was banned in 1977 in North America (WHO, 1993). By 1985, only France and Spain were still producing PCBs.

While PCBs were never produced in Canada, roughly 40 000 tons have been imported into the country from the United States (Tatsukawa and Tanabe, 1984; CCREM, 1986). Slightly more than 24 000 tons of PCBs are recorded as still in use or in storage in Canada (CCREM, 1986).

Cumulative US production from 1930 through 1975 total is estimated 625 000 tons, (in addition to exports of 65 000 tons and imports of 1 400 tons). Of US consumption of 570 000 tons an estimated 340 000 tons were still in service, in 1975 (Versar, 1976). Annual domestic sales by Monsanto have been released for the eighteen years 1957 - 1974 accounting for about 300 000 tons. Monsanto voluntarily ceased US production in 1977. Most other industrial countries (except Japan, which stopped production in 1972) continued production through 1982.

The other major PCB producing firms were Bayer AG (Germany), Prodelec (France) - a sales company jointly owned by Rhone-Poulenc and Pechiney-Ugine-Kuhlmann-Caffaro (Italy), Kanagafuchi (Japan), Cros (Spain) and Chemko Strážské (former Czechoslovakia). It is worth noting that Monsanto (including its U. K. operation) accounted for 542 400 tons, of which 43 000 tons were produced in the U. K. However, 499 000 tons is actually a lower bound estimate of Monsanto´s US production. US EPA has recently used the figure 635 000 tons. All others accounted for 383 200 tons, possibly also a lower bound estimate. The world total was therefore somewhat in excess of 900 000 tons and possibly near to 1.2 million tons.

Table 1: OECD production of PCBs 1930 - 1982 [kT]


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Environmental fate

PCBs evaporate very slowly and they are not very soluble in water. Nevertheless, they have dispersed widely through both atmospheric processes and watercourses and trace amounts are found in soils, surface waters, sediments and air throughout the world. Whereas their stability was a welcome feature for industrial use, their resistance to degradation means that they have accumulated in the environment and their presence will persist long after their use has been phased out. PCBs are soluble in fat and they have been assimilated through the food chain into the body fats of animals. Elevated levels of PCBs have been reported in many aquatic and terrestrial species. Because of this tendency of PCBs to accumulate in animal tissues and concern over possible adverse effects on wild life, they have been classified as "eco-toxic".

Although the use of PCBs is banned in most countries today, its persistence and its widespread use lead to its remaining in the ecosystem and being spread further, to rural and pristine areas of the globe (Wania and Mackay, 1993; Bremle, 1997). According to the global fractionation theory, chemicals emitted in warmer climates volatilise and are transported by air currents to colder areas where they are deposited onto soil and water. The globe has been said to function as a distillation apparatus or as a GC-column separating compounds of differing volatility.

For example, PCB congeners having one chlorine can move world-wide without being deposited, whereas congeners with 8-9 chlorines tend to be deposited closer to the source. The concentration of volatile compounds is thus low in tropical areas and higher in temperate or polar regions (Wania and Mackay, 1996).

In addition to the long-range transport of PCBs globally, there is also a circulation of PCBs from soil and point sources, which influences its concentration in the air on a more regional scale. The temperate industrialised nations, where on through the 1960s - 1970s PCBs was manufactured and used extensively, are regarded as the source areas of PCBs on global scale (Harrad et al., 1994). Contaminated aquatic environments can also act as sources of persistent pollutants in the atmosphere since such compounds are readily volatilised from water, as shown in the Great Lakes in North America (Achman et al., 1994; Hornbuckle et al., 1993) and Lake Baikal in Russia (Iwata et al., 1995). If the fugacity, or escaping tendency, of one compartment exceeds that another, PCBs will diffuse from the former to the latter, volatilising from contaminated soil or water bodies to the air, for example, or being


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deposited from contaminated air to cleaner soil or to water (Bremle, 1997).

A mass balance of PCBs in UK and other countries (Harrad et al., 1994) showed that soil retained a larger amount of PCBs than other compartments did (air, freshwater, sediment, or biota) and is today the greatest source (90 %) of it for the atmosphere through re-circulation. The PCBs deposited from the atmosphere to the soil in the 1960s and 1970s are re-volatilising to the air now as a result of equilibrium partitioning (Harner et al., 1995). The out-gassing of the more chlorinated congeners from the soil has been delayed due to their lower volatility. The volatilisation of PCBs from the soil is dependent on the ambient temperature and on the vapour pressure and lipophilicity of these compounds. The successive line of properties of different PCB congeners ranging from being low to high in chlorination, follows the sequence from smaller to larger molecules, from lower to higher lipophilicity and from higher to lower vapour pressure. The less chlorinated PCB congeners are thus more readily partitioned to the air. The more highly chlorinated congeners, in turn, tend to be associated with particles or with and organic carbon.

The major input of PCBs to freshwater ecosystems is by of the atmosphere (Bremle, 1997). Aerial fluxes of PCBs to the ground occur through (1) rain and snow´s scavenging vapours and particles, i.e. by wet deposition, (2) dry particle deposition, and (3) vapour exchange across different interfaces, such as air/water, air/soil or air/plant surfaces (Bidleman, 1988). Apart from air to water, as rain on the water surface, the PCBs deposited on soil and vegetation can also reach the water body as a result of wash-out by precipitation from the basin area. The types of soils and land use in basin areas also influence the amount of leakage to freshwater.

In water, PCBs can exist either truly dissolved or adsorbed to suspended particles (Eisenreich, 1987; Bremle, 1997). Although the water solubility of PCBs is low, the amount of PCBs dissolved in water is so large. Due to the presence of suspended particles with adsorbed PCBs, the amount of PCBs in water can sometimes exceed what would be expected from the PCB´s water solubility. The water solubility of PCBs can also be enhanced by humic material or dissolved organic carbon being present in water. The transport of PCBs in rivers occurs partly as PCBs that is truly dissolved, partly through its being associated with particles, and partly through the so-called bed load of sediment movements. In rivers containing only small amounts of particles, the major transport of PCBs occurs in the dissolved phase. PCBs loss from the water mass occurs through partitioning or through sedimentation to the sediment (Eisenreich, 1987). The sediment can also act as a source of it through desorption and through resuspension. Volatilisation to air also removes PCBs from the water phase.

The uptake of PCBs in aquatic and benthic biota is mainly governed by the lipophilicity of the compound in question, which can be expressed by its octanol/water partitioning coefficient. Besides the direct partitioning of PCBs between water and the fat pool via gills of fish and other organisms, food is a source of contaminants for aquatic biota. In addition,


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physiological control of uptake, steric hinderance of large molecules, distribution of chemicals within organisms, biotransformation and biodegradation all affect the level of pollutants (Barron, 1990; Larson et al., 1996). Species-specific factors such as fat-content, age-distribution, growth-rate, and prey selection likewise affect PCB concentrations.

For terrestrial organisms, the passive process of exchange between the organism and the surroundings in the uptake and loss of organic pollutants, as is the case for aquatic biota, does not generally occur (Bremle, 1997). The partitioning between air and the lung of an organism is more limited, due to the respiration volume being low compared with that of gill-breathing aquatic organisms. The partitioning between an organism and water is also more thermodynamically favoured than between organisms in the soil, such as earthworms that can gain or lose chemicals via the soil water, the main route for the uptake of pollutants by terrestrial organisms is by ingestion. Aquatic mammalian predators seem to have higher concentrations of pollutants than terrestrial ones. Animals higher up in a food chain often have higher levels of PCBs and other PBT compounds (biomagnification). Top predators, especially in the terrestrial food chain, have a characteristic PCB pattern in which only few of congeners dominate (Bremle, 1997; Bremle et al., 1997). The elimination of PCBs from terrestrial organisms is mainly in terms of metabolisation (Walker, 1990).



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Global distribution of PCBs

During the past three decades, analytical data have revealed global contamination of aquatic and terrestrial environments (Tanabe et al., 1994). In large measure, this is the logical consequence of the physical and chemical properties of PCBs:

● PCBs are highly resistant to chemical and biological degradation. PCBs, particularly the highly chlorinated ones, have been known for some time to persist in soils, water, sediment and biota for long periods of time (IPCS, 1993).

● PCBs are non-polar molecules that can accumulate in fatty tissues. This results in their biomagnification in the higher trophic levels of the food chain (Shaw and Connell, 1986a, b).

● PCBs are found in pristine areas where there are no known sources of release to the environment, demonstrating that PCBs are subject to long-large transport from their initial source (Norstrom et al., 1988).

Researchers have concluded that the major mechanism for this mobility is a cyclical evaporation from soil and water surfaces in which winds lift PCBs into the air along with water vapour and dust, eventually depositing them with rain, snow, or adsorbed to particles. With repeated evaporation and deposition, the net result is movement of PCBs over long distances in the direction of atmospheric air movements. Models of this mobile behaviour correlate well with the measured PCB concentrations in the northern hemisphere (Delzell et al., 1994).

Tanabe et al. (1994) measured PCB concentrations in southern and eastern Asia and the surrounding seas, and pin-pointed the contribution of various PCB sources. From their work, in addition to data gathered from North America and Europe, it is possible to draw some general conclusions:

● Because of their environmental mobility, PCBs eventually enter a global pool of these contaminants and are available for recycling and redistribution (Iwata et al., 1993; Tanabe, 1988);

● Because of the mobility and persistence of PCBs, environmental concentrations of PCBs tend to be uniform throughout the globe (Tanabe et al., 1994);


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● Based on monitoring data, the polar regions appear to be an environmental sink for PCBs (Muir et al., 1992).



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Content | Chapter 1 | 2 | 3 | 4 | 5 | 6 | 6.1 | 6.2 | 6.3 | 6.4 | 6.5 | 6.6 | 7 | 8 | 9 | 10

Trends and environmental re-cycling of PCBs and other POPs

The basic trends of usage and emission to the environment consist from the following steps - they are common for many other POPs (Jones and de Voogt, 1999):

1. Synthesis and development for use earlier in this century, in this case in the 1930s; 2. Increasingly widespread use in Europe and North America and other industrialised

regions through the 1950s and 1960s; 3. Concerns over environmental persistence and foodchain accumulation in the 1960s /

early 1970s, resulting in restrictions in usage in Europe and North America; and 4. Reductions in emissions in Europe, North America and other industrialised regions

arising from the bans / controls in the 1970s through the 1980s and 1990s.

This general pattern may be unrepresentative of the global emission profile when the chemical is used extensively outside of Europe and North America (following a global shift in the place of manufacture).

These trends in emission have had fundamental implications for concentration trends in air, soil, water and sediments and for magnitude and direction of fluxes between these compartments for PCBs capable of dynamic, multimedia exchange. Likely he response to the maximum of emission phase in the 1950s and 1960s has been deposition from the atmosphere to greatly exceed volatilisation to it in the 1940-60/70s and for reverse to have applied in the more recent past. Base on these approaches we can describe the hypothetical responses of the air and the soil compartments to the emission pulse. Air concentration can be expected to respond rapidly to the increasing emission (1940-60s) and to reflect it. However, as the primary sources became controlled / reduced air concentrations initially reduced, but in more recent times may actually have been "maintained" by volatilisation ("outgassing") of recyclable PCB congeners from the terrestrial and aquatic compartments. The time over which they are maintained will be dependent on a number of factors, such as the size of the "reservoir" of compound in the soil/sediment/water compartments, persistence in the soil / sediment compartments, physical-chemical properties of the compound and whether there is free exchange of the compound which has been deposited in the past (i.e. is adsorption / desorption of the PCB completely reversible ?). For some compounds, which may have entered the soil or water body primarily associated with particulate deposition, outgassing will be limited and concentrations / burdens in these compartments will tend to remain high / increase.


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For others, which readily enter the gas phase, outgassing will result in the soil / water body concentration / burden declining. Research in the Great Lakes area provides powerful evidence for these long-term trends and reversals of the air-surface exchange flux (Jones and de Voogt, 1999). Sediments cores show deposition of PCBs and other POPs to the lakes reflecting the hypothetical emission trend, whilst mass balance calculations, analysis of paired air-water samples and monitoring of air concentrations all provide evidence that volatilisation now exceeds deposition, i.e. the water bodies now act as sources to atmosphere, rather than as sinks. Historical re-constructions of soil and air concentrations for PCBs in the U. K. also suggest a reversal in the long-term net flux (Harner et al., 1995). Several researcher have shown atmospheric concentrations of re-cyclable POPs respond to seasonal or diurnal changes in temperature (Halsall et al., 1995; Hillery et al., 1997; Lee et al., 1998). When this happens, it suggests that the air concentration is "controlled by" secondary re-cycling rather than fresh/ongoing primary emissions (e.g. as for PCBs).



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Content | Chapter 1 | 2 | 3 | 4 | 5 | 6 | 6.1 | 6.2 | 6.3 | 6.4 | 6.5 | 6.6 | 7 | 8 | 9 | 10

Environmental contamination

PCBs are now believed to be universally distributed throughout the world. Major concern for the possible health effects of PCBs arose in the early 1970s. A major human health catastrophe, the Yuosho incident, in 1968 probably had a great deal to do with forcing the problem into view (Kuratsune et al., 1972). The Yusho incident involved contamination of rice with PCB fluid that was being used as a heat transfer material.

Most trend data dealing with widespread dispersal indicate concentrations are declining. However, there still are several hot spots where, in spite of trends toward a decline, the levels are such that mitigative actions are being considered (industrial harbours, vicinity of former producers, industrial areas, etc.).

There are several ways PCBs enter the environment. Historically, the most common way was direct waste discharge from manufacturing facilities and industries, which employed large amounts of the materials in their manufacturing. Die-casting equipment once employed large quantities of PCBs, and these industries used large amounts of the PCBs mixtures. Today many of the PCB hotspots occur at locations where these types of operations were centred. Additional locations of high levels of PCBs occur where improper disposals of PCBs have been carried out, and PCBs are a common contaminant in hazardous landfill sites across the world. Most of the direct emissions from historical sites were by aquatic routes, and present-day problems associated with these discharges now reside in soil and sediments of lakes and rivers near these sites.

While the atmosphere has provided an effective transport medium for PCBs, terrestrial soils have provided the largest repository (Sweetman and Jones, 2000). During the 1950s through the 1970s, net deposition to soils from the atmosphere was occurring as a result of high primary emissions and hence air concentrations. Following restrictions on production and use, direct emissions to the atmosphere had reduced by the late 1970s / 1980s. However, by this time the soil repository had built up to a level that, as atmospheric concentrations declined, it could provide a secondary source of PCBs back to the atmosphere. As a result, there is much interest in the long-term fate of PCBs in the environment; notably the balance between primary and secondary (recycling) sources to the atmosphere, their global redistribution, and long-term dynamics governed by different physical, chemical, and biologically mediated loss processes. Among the processes that "remove" PCBs from the environment and the "pool" available for recycling are (i) reaction in the atmosphere with


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OH radicals; (ii) microbially mediated degradation in soil and the formation of irreversibly bound residues in soils and sediments; (iii) burial in soils, sediments, peat, and ice; and (iv) incorporation into the deep oceans. However, at the present time the relative importance of these processes is unclear, and there is a lack of long-term monitoring data on concentrations from which to quantify the "rates of disappearance" of PCBs and to gain clues about the relative importance of the different processes governing there rates.

The reliable estimates of the historical/contemporary emissions / sources of POPs such as PCBs are very difficult (and in some cases, almost impossible) to achieve (Jones and de Voogt, 1999). They are of fundamental importance for effective source reduction measures and for national / regional / global environmental inventories, budgets and models. Quite basic information is sometimes still lacking.



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The case of Lake Baikal

Lake Baikal is a unique freshwater ecosystem that has been declared a UNESCO World Heritage Site (Mamontov et al., 2000). Lake Baikal, located in east-central Asia, is the deepest (1 637 m) and oldest (25 million years) lake in the world. It is 636 km long and from 25 to 79.5 km wide. The more than 2 000 km of shoreline enclose an area of 31 500 km2, and its basin area is approximately 570 000 km2. 70 % of the species found there are endemic.

The first investigation of POPs in the Lake Baikal ecosystem were conducted by Russian scientists in the early 1980s (Bobovnikova, 1985; Malakhov et al., 1986). They analysed some biotic samples (plankton, omul, blubber) and attributed the presence of PCBs to long-range atmospheric transport and classified the levels as background. However, Bobovnikova and Dibtseva (1994) later reported on the analysis of blubber from more than 100 seals from Lake Baikal and found no evidence of a decrease over the period 1981-1989 as had been observed in other water bodies in the industrialised world. Studies in the early 1990s provided no evidence of decline, the levels continued to be high (Kucklick et al., 1994; Grosheva et al., 1995; Nakata et al., 1995a) and concerns were raised that the PCB contamination might be adversely affecting the seal population (Nakata et al., 1995b).

In the late 1980, PCB concentrations were determined in the air of towns in the Angara River valley to the north of southwestern tip of Lake Baikal (Surnina et al., 1991). In towns with little industry, the Sum of PCB concentration was less than 1.5 µg.m-3, but in the industrial towns Usolýe S. and Selenginsk levels of 22 and 7.3 µg.m-3 were measured. The authors concluded that this industrial region between Irkutsk and Cheremkhovo might be influencing PCB levels in Lake Baikal. McConnell et al. (1996) came to a similar conclusion on the basis of air samples collected in the summer of 1991 that showed Sum of PCB concentrations to be an order of magnitude higher in this industrial region than on shore of Lake Baikal 70 km to the southeast. Snow samples collected in 1995 and 1996 showed high concentration of PCBs in the industrial region with decreasing levels moving toward the lake. Water samples collected in 1993 revealed that PCB concentrations were an order of magnitude higher in the southern basin than in the northern basin, and the authors concluded on the basis of the PCB patterns and the bioaccumulation behaviour that the PCB contamination was recent (Kucklick et al., 1993). Furthermore, simultaneous measurements of air and water concentration in 1991 and 1992 indicated that Lake Baikal is a source of PCBs to the atmosphere (Nakata et al., 1995; McConnell et al., 1996), again suggesting that PCB


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inputs have been recent as the lake has not sufficient time to approach equilibrium with the atmosphere. Taken together, these results suggest the following scenario: PCB were emitted from a source in the Angara River valley, transported with the prevailing winds up the valley to Lake Baikal, and deposited in the southern basin from where they slowly spread throughout the lake.

A different explanation was offered by Iwata et al. (1995). They analysed water samples at different locations and found higher concentrations at the mouth of the Selenga River and its southwestern corner of the lake than at other locations. They suggested that the Selenga River and smaller rivers in the south were significant PCB sources. Another possible sources is the a large pulp mill in Baikalsk on the southern shore, the highest PCB concentrations were found in the samples collected closest to this plant.

Mamontov et al. collected samples of pelagic three predatory fish, two species of pelagic sculpin and soil from the surroundings of Lake Baikal during the summer of 1997 (Mamontov et al., 2000). One from the predatory fish was omul, an endemic whitefish, which migrates constantly throughout Lake Baikal. The other two were sedentary, living only in the delta of the Upper Angara River, which drains a remote virtually unsettled area with no known sources of PCBs. The levels in omul were compared with those in the other two species to obtain an indication of whether the PCB contamination in Lake Baikal originates from continental background (as represented by the Upper Angara River drainage basin) or from other regional or local sources. Two species of pelagic sculpin were sampled from three locations in the northern, central, and southern part of Lake Baikal. These fish are sedentary and were used as an indicator of regional differences in PCB levels in the lake. Soil samples were collected at 34 sites around Lake Baikal and in the Angara River valley between Lake Baikal and Zima. Soil has been shown to contain more than 90 % of the PCBs inventories in terrestrial ecosystems. Since the atmospheric deposition is the only plausible source of these compounds in most of the land surrounding Lake Baikal, the inventory of soil can be used as a measure of historical atmospheric deposition. The purpose of this sampling program was to measure the regional distribution of the PCB inventory in soil.

The levels in the two pelagic predators that live in pristine rivers flowing into northern Lake Baikal are an order of magnitude lower than in the omul. This indicates that PCB contamination in Lake Baikal does not originate from the continental background. It must be due to local or regional processes. The levels of PCBs in sculpin samples showed increasing concentrations from the north to south. The variability in the PCB soil inventories was ranged from 0.2 to 1 380 ng TEQ.m-2. There was a systematic regional distribution in the soil inventories, with decreasing levels moving away from Usolýe, both down the Angara River valley and up the valley toward Lake Baikal. The predominant northwesterly winds and the topography of the Angara River valley which is enclosed by hills favours the movement of air masses from the industrial region up the valley to the source of the river where they are dispersed over the lake. Since atmospheric deposition is


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the only plausible source of these compounds in the soils, this indicates that there is/was an atmospheric source of PCBs in the Usolýe area and that this source contaminated the surrounding region including the southern part of Lake Baikal. The spatial distribution of PCBs in soils in agreement with the spatial distribution measured in snow collected around the southern shore of the lake and in the Angara River valley during the winters of 1995 and 1996. Assuming the PCBs atmospheric deposition to be the major source, the corresponding estimate for the Sum of PCBs was round 8 000 kg. The Usolýe source has clearly had a large impact on Lake Baikal, although it is located some 100 km from the shore of the lake.



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The UK case

The U.K. environmental loading of PCBs in the first part of 1990s was estimated by Harrad and co-workers (Harrad et al., 1994). Of the estimated 40 000 t of PCBs sold in the U.K. since 1954, only an estimated 1 % (400 t) were present in U.K. environment in the first part of 1990s. The bulk (93.1 %) of the estimated contemporary U.K. environmental burden of PCBs was associated with soils, with the rest found in seawater (3.5 %) and marine sediments (2.1 %). Freshwater sediments, vegetation, humans and sewage sludge combined account for 1.4 % of the burden, whilst PCB loading in air and freshwater were insignificant.

The contemporary flux of PCBs to the U.K. surface was estimated at 19 t.yr-1 and compared with an estimated annual flux to the atmosphere of 44 - 46 t. This implies that the major sources of PCBs to the U.K. atmosphere have been identified and that there was currently a net loss of these compounds from U.K. The main sources were volatilisation from soils (88.1 %), leaks from large capacitors (8.5 %) and the production of refuse-derived fuel (2.2 %).

Retrospective analysis of dated sediment cores, vegetation and soils have indicated that environmental transport from North America and continental Europe introduced PCBs into the British environment well before the onset of their commercial production in U.K. in 1954. Since that time, the input of PCBs to the U.K. environment had essentially reflected temporal trends in U.K. use. After peaking in the 1960s they declined rapidly through the 1970s following restrictions on PCB use.

PCB air concentrations have been measured at a meteorological site in northwest England since 1992 (Sweetman and Jones, 2000). Examination of this data set, comprising over 200 data points, suggests that PCB levels are decreasing with average congener specific half-lives ranging from approximately 2 to 6 years. With the exception of congener 52, which shows the steepest decline, the slopes of other congeners (28, 101, 118, 153, 138) were not found to be significantly different from each other. A U.K. mass balance model has been used to examine which factors are likely to be controlling present and future air concentrations. This allowed a range of fate scenarios to be examined and the controlling fate processes to be scrutinised. Estimates of fluxes using contemporary soil and air concentrations suggest that the observed long-term decrease of PCB levels in U.K. air likely to be influenced by several factors, including existing primary emissions and recycling,


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volatilisation from soil, advective losses from the U.K. atmosphere, reaction in the atmosphere, and soil fate processes such as microbial degradation.

The model sampling site Hazelrigg used for these studies is a meteorological station located in a semi-rural location outside Lancaster on the northwest coast of England, approximately 5 km from the Irish Sea. Various frequency of sampling was used during several different studies, which were performed by this group. The observations taken at Hazelrigg have been assumed to be typical for the U.K. as a whole.

As a result of these model calculations, the authors suggest that deposition of PCBs from U.K. atmosphere is currently approximately balanced by volatilisation from soil. The importance of degradative processes such as atmospheric OH radical reaction is still unclear. Remaining primary emissions (or those resulting from recycling) appear to be still supporting the U.K. atmospheric burden, but in the long term, with the continual reduction of these sources, it will be fate processes within soil that will most likely control the long-term fate of PCBs, their supply to the atmosphere, and "drive" their global cycling.

The similar trend of decreasing of PCB air concentrations was observed in Czech regional background observatory at Košetice.



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The "third pole" case (Himalayan lakes)

Remote areas are in general more vulnerable to the pollution by various POPs because climatic conditions enhance residence times in abiotic compartments and the trophic webs in cold environment are very simple, characterised by lipid-rich top predators in which lipophilic compounds are readily accumulated (Galassi et al., 1997). According to the "cold condensation" theory, compounds with higher vapour pressure condense at colder latitudes and altitudes (Wania and Mackay, 1993). However, once trapped in snow and ice during the cold season, these compounds can evaporate from the snowpack when the temperature rises, constituting a "local" source of pollution (de Voogt and Jansson, 1993). The role of this "secondary" pollution source in remote areas is still unclear. Seasonal variations have not been investigated extensively in remote regions due to difficulties in undertaking expeditions in harsh conditions.

The availability of a permanent laboratory at 5 000 m a.s.l. (Pyramid) in the Khumbu Valley represents a unique opportunity to undertake environmental studies in an area which can be considered as the "third pole". In the framework of the Ev-K2-CNR project, scientific expeditions were organised yearly beginning in 1992 and environmental samples have been collected from several high altitude lakes for biological, chemical and limnological characterisation. Samples of sediments, waters and zooplankton were collected in two lakes and analysed for PCBs and OCPs contents with the aim of contributing to the understanding the role of "local" organic compounds cycling in the more general movement of these compounds from polluted to remote areas.

Superior Lake and Inferior Lake are clear-water high altitude water bodies located in the Khumbu Valley, Sagarmatha National Park, Nepal, at 5 050 m a.s.l. Superior Lake is located in a basin on the eastern side of a ridge and has an outflowing stream that connects it with Inferior Lake, at 150 m lower altitude. The sedimentation rate for Superior lake (150 mg.cm-2.y-1) is 10 times higher than for Inferior Lake, the rate of deposition of organic matter was 8 and 2 mg.cm-2.y-1 in Superior and Inferior Lakes, respectively.

PCBs (and OCPs similarly) were more concentrated in the first sediment layer in agreement with higher pollution load in recent years than in the past and with a higher concentration of organic carbon than in deeper sediments. Only nine of the 16 PCB congeners were detected in the zooplankton and even less in water although it was concentrated 10 000 times. The PCB profile of the four layers of sediment of Superior Lake, covering a period of about ten


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years, from 1979 to 1992 was similar to that of commercial mixtures of Aroclor 1254 and Aroclor 1260. Lower chlorinated PCBs of Aroclor 1242 and 1248 mixtures were not present in these samples. Since persistent increases with chlorination, the authors expected to find more chlorinated congeners in the oldest sediments. Probably, this contradictory result might be abscribed to changes in uses. Inferior Lake sediments showed a different pattern with an enrichment of less chlorinated congeners in both layers (1992-1972, 1972-1052). As these two layers are very similar to each other, although they represent the historical records of very different periods of PCB use and diffusion in the world, differences between the two lakes are more likely to be explained by phenomena occurring on a local scale than from long-range transport.

The PCB concentration in the superficial sediments of two Himalayan lakes was higher than those determined for example in Northern Italian lakes such as Lake Como (161 ng.g-1 dry wt) or Lake Maggiore (64 ng.g-1 dry wt) sediments for the same deposition period. Since the organic matter content of the most recent layer of Superior Lake sediment is the lowest of the above mentioned lakes its higher contamination should be due to the cold condensation phenomenon.

Interesting findings can be drawn comparing the results obtained for the two Himalayan lakes. Comparing the PCB congener distribution, it is evident that Superior Lake sediments reflect the composition of commercial PCB mixtures of Aroclor 1254 and 1260, while Inferior Lake sediments are enriched in the lower chlorinated and more volatile congeners occurring in these mixtures. As long-range contamination sources must be the same for the two aquatic environments, only local recycling could explain the observed differences.

Lower chlorinated congeners (such as 101 and 110) are released from suspended particles and superficial sediment into water but do not escape into the atmosphere (in term of net flux). Dissolved and particle-bound PCBs are transported from Superior into Inferior Lake since the first is a tributary of the latter. Compounds having very low Hc/Kow ratios tend to

be retained by particles. As the warm season is very short at this altitude, probably there is not enough time to reach equilibrium conditions for desorption of extremely lipophilic compounds. PCBs accumulated in the snowpack in the drainage basin of the Superior Lake appear to be transported by particles, as is indicated by the high sedimentation rate. Superior Lake acts as a settling pond for Inferior Lake, where the sedimentation rate is ten times lower. Therefore, this latter lake is probably much more influenced by local re-volatilisation and deposition phenomena than by pollutant transported from long distances and trapped in snow and ice.



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The Norway mosses case

There are many data for concentrations of PCBs in different environmental compartments within varying climatic areas, but there are few studies that have been carried out with the prime aim of obtaining evidence to support the global fractionation theory (Lead et al., 1996). This could be due to the difficulties associated with obtaining such data. For example, although the use of PCBs was restricted throughout much of Europe and North America in the late 1970s, there will still be source areas, and it will therefore be difficult to collect samples that are far removed from any possible localised sources. In order to infer possible global fractionation, temporal data are required for concentrations at different latitudes and samples that could provide such information are hard to obtain. There are also uncertainties over the PCB distribution between terrestrial and aquatic environments.

Many studies have confirmed that plants will play an important role in the global cycling of POPs including PCBs since (1) they cover over 80 % of the earth´s land surface, (2) the surface area of plants is generally much greater than the area of the ground they cover, and (3) vegetation has a lipid fraction which is likely to accumulate lipophilic compounds such as PCBs (Lead et al., 1996). Mosses are thought to be ideal biomonitors for air pollution for these three reasons and also because they depend entirely on the atmosphere for delivery of nutrients and lack both cuticle and internal transport mechanisms.

More than 500 samples of the epigeic moss Hylocomium splendens were collected from different sites across Norway in the summer 1977 and in 1985 and 1990. These archived samples have been analysed for a range of PCB congeners. The Sum of PCB concentration (sum of the concentration of the 37 congeners screened) declined in all samples from all locations. It is probable that this decline reflects the reduction in the global use and manufacture of these compounds. The study has provided some evidence to suggest that, since 1977, the concentrations of hexa- and hepta-PCBs have declined to a greater extent in the south than in the north of Norway and that over this time period the relative importance of the heavier chlorinated PCB congeners has increased in the colder areas of Norway. These observations are consistent with the global fractionation theory, but these suggestions are only tentative and should be viewed with caution until further more rigorous studies on the evidence for global fractionation (Lead et al., 1996).



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The Greenland and Faroe Islands case

PCBs similar as many other POPs are widely spread in the environment and due to air masses which move to the Northwest Atlantic from heavily industrialised areas and from agricultural regions where pesticides are used, the contaminants will be transported to the Arctic. Several determination of various POPs including PCBs were performed in various biotic samples from Greenland and Faroe Islands environment in order to elucidate the current environmental status of the Arctic (Fromberg et al., 1999). The literature concerning the POPs in the environment of Greenland and the Faroe Islands covering the period up to 1995 has been revisited. Thus as the former quantified the content of PCBs by comparison to a technical mixture of them (e.g. Aroclor 1254), the latter analyses typically are quantified on a single congener level. The different matrices analysed comprise human, mammals, birds, fish, mussels and sediments.

Studies based on single congener determinations reveal the highest levels reported for whale and purpoise blubber and lower levels in seal blubber and in bird plasma. In earlier data based on quantification by comparing with an Aroclor standard, the highest levels were reported for whale blubber, whereas lower levels for seal blubber were noted, the lowest levels being found for walrus blubber. The variations within the single matrices are large and it is therefore only possible to give a general description of the data. Levels of PCBs and other POPs in biota from Greenland seem to have decreased over the past 20 years, however due to the relative low number of determinations, differences in age and sex as well as differences in quantification techniques it is difficult to compare earlier and more recent data. Hence, conclusions should be drawn only with caution.



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The Central and Eastern European countries case

In the former Czechoslovakia, PCBs were manufactured from 1959 to 1984 in a chemical plant in eastern Slovakia under the commercial name Delor. From the total 21 482 t produced (+ about 1 600 t PCB wastes), 46 % was exported and the remainder was appointed for the home market of former Czechoslovakia. Within both countries (Czech Republic and Slovakia), PCB formulations may be currently used only in the closed systems and they are gradually replaced. Currently, waste landfillings is considered to be the most relevant source of environmental pollution by PCBs in these countries. Estimated contribution of applied paint to total PCB pollution within Slovakia is about 5 % and that of industrial and municipal waste incinerators is 9 %.

It was recently rather unknown that Poland had its two own technical PCB formulations - Chlorofen, which was similar in appearance and composition to Aroclor 1262, and Tarnol, which was similar to Aroclor 1248 (Falandysz, 1998).

Tarnol, which was also called Chlorowany bifenyl, was a low chlorinated technical PCB formulation manufactured between the years 1971 and 1976 by the company Zaklady Azotowe in Moscice near the city of Tarnow in southern-east Poland. The mixture is in its physical appearance and properties similar to well known foreign technical PCB mixtures such as Aroclor 1248, Clophen A-40, Phenoclor DP-4, Fenchlor 42 or Kanechlor 400. Tarnol was a product of the "anti import philosophy", which was on the agenda of the government in the 1970s. The total quantity of manufactured Tarnol in 679 tonnes. Tarnol was a colour-less clear liquid of density 1.45-1.47 g.ml-1 in 20 °C. Chlorobiphenyl isomer and congener composition of Tarnol is unknown in detail. According to the manufacturer of Tarnol this mixture was composed mainly of trichlorobiphenyls with di-, tetra- and pentachlorobiphenyls as a minor constituents. Nevertheless, the composition of Tarnol was not confirmed using the capillary gas chromatography and low/high resolution mass spectrometry (HRGC-LR/HRMS) for analysis. No official data on the kinds of use of the Tarnol were released - it seems that it was used exclusively as an dielectric fluid mainly for the transformers but use as dielectric in capacitors could be also possible.

Chlorofen was a highly chlorinated (63.6 % Cl) PCBs formulation manufactured in the town of Zabkowice Slaskie in southern Poland. The mixture was a light to dark-brown sticky and viscous resin mainly composed of PCB congeners with 5 to 9 chlorine atoms that comprised 99.55 % of total PCBs. The average number of Cl per biphenyl molecule in


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Chlorofen is 7.3 and the average molecular weight is 405.4. Chlorofen contains at least 59 PCB congeners with the major components such as PCBs Nos. 153 of hexa-, 176, 180 and 187 of hepta-, 194, 195, 198, 201/196 of octa- and 206 of nonachlorobiphenyls.

Industrialised countries such as USA and Western European countries have some legislative measures for controlling the flux of PCBs in the environment. One important aspect is control of PCBs sources such as transformers, capacitors, electric motors etc. The materials containing more then 50 µg.g-1 are subject to some regulations. These regulations are adopted in CEE countries. Since 1993, in Poland the waste oils containing PCBs were included on the list of hazardous substances, but to the present days the flux of these pollutants was not a subject of any regulation (Lulek, 1996). Recently available data (Gurgacz, 1994) have indicated that in national power plant installations about 1 400 tons of transformers and capacitors oils are used. However, unknown is even estimated amount of the waste industrial oils (transformers, capacitors, motors etc.) occurred in the trade. An assessed percentage of PCB contaminated equipment is in the case of transformers 0.38 %, capacitors 35 - 50 % and other electromagnetic equipment 25 - 50 %. An assessment amount of PCB contaminated oil / capacitors / other electromagnetic equipments is up to 10 000 tons. Determination the levels of PCBs in the random samples of waste motor and transformer oils collected from different regions of Poland showed that these concentrations in the most of samples did not exceed the limit value of 50 µg.g-1 (Lulek, 1996).

There has been no PCBs production in the other countries of the region. PCBs can still be found in many closed systems, dumps and environmental matrixes in all the countries in the region. For example, in Croatia in 1997, more than 2 000 tonnes of PCBs oils from various countries were imported (Sinovcevic, 1998).

Part of PCBs amounts from various countries of the region was exported to the France for destruction. Part of PCBs amount used in the region, was liquidated legally, and part probably illegally during the period of main economic changes in these countries in the early 1990s. Unknown part of total used amount of PCBs is still in the various environmental compartments.

The recent inventory of PCBs in Slovakia (Kocan et al., 1999) gave the following actual PCBs equation in this country:

PCBs (Wastes from production - 1 606 t) + PCBs (Products - 4 071 t) = PCBs (Still used - 960 t) + PCBs (Liquidated - 368 t) + PCBs (Disposed - 1 605 t) + PCBs (Rest - 2 744 t)

A recent pilot study aimed at five selected Slovakia´s districts has shown that PCB levels in the Slovak human population are substantially higher than those in many other countries (Kocan et al., 1994a, b, 1995, 1996). Several times higher PCB content in comparison with other districts was found in human adipose tissue, blood and milk samples collected in


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Michalovce district, i.e. in the district in which PCBs were manufactured. Chemko chemical factory in Strazske produced from 1959 to 1984 in a total amount of about 21 500 tonnes (Kocan et al., 1998). Especially in the first half the manufacture, considerable amounts of PCBs released into the environment (mainly into watercourses and soil) due to poor technological measures. In addition, former ignorance about the environmental persistency of PCBs and their harmful effects on living organisms caused that almost no attention was paid to PCB releases at that date.

Very complex study on PCB contamination was performed in this region (Kocan et al., 1999a, b). PCB levels found in ambient air, soil, surface water, sediment and wildlife (fish and game) samples collected in 1997/98 (i.e. 14 years after the manufacture had been stopped) at the broader neighbourhood of a former PCB production plant in eastern Slovakia were reported. Stropkov district, which is about 60 km (upwind and upstream) far from the contaminated Michalovce District, was selected as a comparative background area.

Environmental contamination starting through manufacturer´s effluent canal has manifested itself in increased PCB levels observed in ambient air, soil, surface water and water sediment around Michalovce district and other sites where PCBs were applied. As a consequence of that, wildlife living in local forests and fields and especially fish caught in contaminated waters and contained PCBs often at very high levels. Results from an ongoing project are also showing that the food and human population of Michalovce district is much more contaminated with PCBs than the rest of Slovakia.

In Croatia, there are 405 users of 22 532 PCBs capacitors and 293 users of PCBs transformers (Sinovcevic, 1998).

The use of PCBs in Slovenia increased after 1960, when an ISKRA condenser factory was built in Semic, Bela Krajina (about 80 km south-east from Capitol Ljubljana) (Polic and Leskovsek, 1996). PCBs were introduced into the production process in 1962 (until 1970 Clophen A-50 and A-30 supplied by Bayer, FRG and between 1970 and 1985 Pyralen 1500 supplied by Prodelec, France). The consumption of PCBs by ISKRA in period 1962-1985 totalled about 3 700 tons with a PCBs waste rate of 8 - 9 % in the form of waste impregnates, condensers, etc. By 1974, 130 tons of waste containing around 70 tons of pure PCBs, were dumped at various waste sites within five km round the factory. After 1975 waste impregnates were collected and sent to France for treatment (170 t), whereas smaller waste condensers were still disposed of at local waste site. Measurements in 1982 showed very high concentration of PCBs in the environmental compartments (air, water, sediments), as well as in food and in animal and human tissues (Polic and Kontic, 1987).



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Control of the industrial use of PCBs

The current focus on issues related to PCB use, is the management of PCBs in existing equipment (mainly electrical) prior to phase-out (OECD, 1991). The aim is to ensure safety and in order to prevent loss of PCBs to the environment. The measures adopted by OECD countries include inventories of PCBs and equipment, labelling, cleaner industrial processes, periodic inspection of PCB equipment, and accident response contingency plans.

Handling, storage and transport of PCBs once removed from service has also been of great concern. Several cases of spills and accidental leakages have been reported and the clean-up can be difficult and very costly, as the Italian case demonstrates.

Fires involving PCBs can be very dangerous (Journault et al., 1988). At low temperatures, PCBs are non-flammable. As temperatures increase (500 - 600 °C) PCBs begin to decompose and yield small amounts of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), which are dispersed in air or absorbed on soot. At even higher temperatures (> 700 °C), PCBs become flammable, generate a great deal of heat and carry a self-sustaining flame that is difficult to extinguish. There are a number of examples of fires, which have spread to PCB transformers and have resulted in this type of PCB-fire.



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Management of PCBs

The management of waste PCBs and PCB-containing wastes will be a major concern for the foreseeable future. A significant portion of all the PCBs ever produced remains in service, in storage or in landfills (Tanabe, 1988). As existing uses are phased out they become waste and add to the already large stockpile of PCB wastes.

Canada and other countries have set a limit of 50 ppm below which PCB wastes may be disposed of in approved hazardous waste disposal facilities. Wastes containing greater than 50 ppm PCBs are subject to regulations calling for the use of special destruction technology.

Various destruction technologies and facilities have been developed and tested over the past two decades (Environment Canada, 1988). Degrading or destroying the PCB molecule generally is the only acceptable procedure. In Canada and other countries, high temperature incineration and chemical treatment are approved method of destruction bulk PCBs. At less than optimum temperatures and operating conditions, two problems may emerge. First, the PCBs may be volatilised and released into the environment via the stack. As well, trace quantities of highly toxic PCDDs and PCDFs (dioxins and furans) may be formed and dispersed to the environment (Coghlan, 1993).

Any PCB waste management activity should include the following elements:

● inventory of the amounts and location of bulk PCBs and PCB equipment; ● collection and storage of PCB wastes; ● ensuring that adequate domestic destruction facilities or foreign facilities are

available; ● monitoring of these activities (Environment Canada, 1991).



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Conclusions

Contamination of the environment by PCBs was identified as a problem in the late 1960s. During the 1970s and 1980s actions, were taken by OECD countries and others to stop PCB production and the manufacture of equipment containing PCBs. However, while measures have been taken to address PCB production, it is of considerable concern that up to two-thirds of the 1.2 million tons ever produced are either still in use or in storage.

The world´s oceans have become a giant reservoir for PCBs. It has been estimated that over the United States alone, 900 tons of PCB cycle annually through the atmosphere (IPCS, 1993). Measures required to prevent adding further to this environmental burden necessitate the safe management of existing PCB-equipment and the orderly and safe phase-out and decommissioning of PCB-equipment. These measures include fire and accident prevention as well as prevention of evaporation and leakage. In the phase-out of PCB-equipment, care must be taken during removal from service, decontamination and storage, to avoid the loss of PCBs to the environment.

Phase-out of existing PCB-equipment is directly related to the management of PCB wastes. Destruction is required for that which contains PCB levels greater than 50 ppm. Although present destruction technology is adequate and appropriate, more facilities will need to be established in order to handle the enormous volume of PCBs, which are currently in use or in storage throughout the world. It is imperative that a coordinated international approach is taken among nations to address waste management issues. As a first step all nations should proclaim their commitment to the Basel Convention on the management of hazardous wastes and to the UNEP/FAO Prior Informed Consent procedure.

PCBs typify many of the unique properties inherent with POPs: persistence, tendency to bioaccumulate, semi-volatility and mobility in the environment. The experience of international community in attempting to control PCBs has clearly demonstrated the necessity of safely managing PCBs throughout their life cycles in order to prevent further releases to the environment. The PCB example will also prove to be valuable in addressing other POPs.



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