Polychlorinated biphenyls in freshwater and marine water

​Toxicant default guideline values for protecting aquatic ecosystems

October 2000

Description of chemical

Polychlorinated biphenyls (PCBs) (CAS 1336-36-3) are mixtures of various isomers and congeners. The commercial name of the product is followed by an internationally accepted 4-digit code: the first two digits indicate that the mixture contains biphenyls (12), triphenyls (54) or both (25, 44); the last two digits give the percentage by weight of chlorine in the mixture. A few of the PCBs did not appear to fit this pattern.

PCBs are generally biphenyl or triphenyl structures, attached by a C–C bond, with various degrees and positions of chlorine substitution. There are 209 possible PCB congeners (Hawker & Connell 1988) and up to 132 have been identified in commercial formulations (Safe 1990). Fewer than 100 congeners would be of environmental significance because of their low concentrations (Niimi 1996). They have molecular weights between 292 and 361 and extremely low solubility in water (HSDB 1996), which decreases with increasing chlorine substitution (CCREM 1987). PCBs with chlorines in para positions or in 3, 4 or 3,4,5 positions tend to be more toxic and persistent in tissues (Eisler 1986). Coplanar congeners are of considerable toxicological significance (Tanabe 1988). The current analytical practical quantitation limit (PQL) for aroclor 1242 and 1254 is 0.1 µg/L (NSW EPA 2000).

Uses

PCBs have been widely used as dielectric fluids for capacitors and transformers, as heat transfer fluids, plasticisers, lubricant inks, fire retardants, organic chemical solvents, paint additives, immersion oils, sealing liquids, adhesives, laminating agents, waxes and dust removers (Farrugia 1988, Safe 1990). PCBs commonly are highly lipophilic (increases with increasing chlorine substitution) and high stability under normal or extreme conditions. Hence they tend to bioaccumulate in terrestrial and aquatic organisms and, along with dichlorodiphenyltrichloroethane (DDT) residues, are globally distributed (Safe 1990, Tanabe et al. 1994).

Environmental fate

Mono-, di- and tri-chlorinated PCBs (e.g. aroclor 1221 and 1232) biodegrade more rapidly than tetra-chlorinated PCBs, such as aroclors 1016 and 1242. The more highly chlorinated biphenyls (e.g. aroclor 1248, 1254 and 1260) resist biodegradation (HSDB 1996), although the recent understanding of the coplanar structure of some PCBs has shed more light on their relative degradation (Coristine et al. 1996). PCBs absorb strongly to soils and sediments or suspended sediments (HSDB 1996). PCBs bioconcentrate in aquatic organisms as they are highly lipophilic. Log bioconcentration factors (BFs) vary from 3.26 for monochloro to 5.27 for hexachloro-substituted PCBs. Log BFs for different aroclors were around 4.6 for aroclor 1016, 4.43 to 5.02 for aroclor 1254 and 5.28 for aroclor 1260 (HSDB 1996). Log K_ow values calculated for 209 PCB congeners were between 4.09 and 8.18 (Hawker & Connell 1988). PCBs can be widespread in the aquatic environment due to long-range atmospheric transport. Concentrations can be in the low ng/L range in Northern Hemisphere freshwaters and marine coastal waters and in the pg/L range in oceanic waters (Niimi 1996). Tanabe et al. (1983) measured PCB concentrations between 42 and 72 pg/L in antarctic Ocean Waters. Most PCB contamination in Australia is associated with large urban centres (Thompson et al. 1992). PCB levels in fish near Sydney in the 1970s and 1980s were around 400 to 900 µg/kg and figures as high as 7200 µg/kg were found in muscle of red morwong Cheilodactylus fuscus caught off a major sewage outfall (Scribner et al. 1987, Thompson et al. 1992). PCB levels have declined more recently with concentrations in muscle of red morwong being around 200 to 300 µg/kg (Lincoln Smith & Mann 1989). Similar trends were found in comprehensive sampling of sediment and tissue of mussels, Mytilus edulis, in Port Phillip Bay near Melbourne (Thompson et al. 1992).

Environmental effects

Human health concerns about PCBs have arisen from a number of agricultural and occupational exposures with unfortunate consequences (Safe 1990). Environmental concerns have focussed on their global occurrence and accumulation in fat of marine mammals (Tanabe et al. 1994). Also, in recent years, particular PCBs with a coplanar structure have been identified as having particularly high toxicity because of their similarity of action to dioxin, through the cytosolic protein, aryl hydrocarbon (Ah)-receptor signal transduction pathway (Safe 1994). These include 3,3',4,4'-tetrachlorobiphenyl (tetra CB), 3,3'4,4'5-pentaCB and 3,3',4,4'5,5'-hexaCB while 3,4,4',5-tetraCB has similar activity and mono-chloro coplanar PCBs are also active. Coplanar PCBs have been analysed in aroclors 1242, 1254 and 1260. They have also been demonstrated to exhibit slower uptake (over 17 d) and depuration (over 32 d) in green mussels (Perna viridis) than other PCB congeners (Kannan et al. 1989).

Confirmatory results were obtained with the oyster (Crassostrea virginica) (Sericano et al. 1992). Rainbow trout (Oncorhynchus mykiss) also eliminated these PCBs more slowly (Coristine et al. 1996). Freshwater fish from lakes and rivers in Canada and Scandinavia that had no known source of local PCB contamination contained between 1 and 50 µg/kg of PCBs (Niimi 1996). The analogous figures for marine waters around the world were similar (Niimi 1996) but an amphipod from the Arctic Ocean had between 480 and 3000 µg/kg dry weight (Bidleman et al. 1989). Higher PCB concentrations were found in organisms at higher trophic levels, and indication of biomagnification (Niimi 1996). Toxicity data for 11 PCB congeners are presented in Table 8.3.20, along with environmental concern level (ECL) values to protect only from acute toxicity, not bioaccumulation. Toxicities to fish for additional PCBs (96-hour LC50) were 50 mg/L for aroclor 1262 and 1268 and 25 mg/L for aroclor 1260.

It is difficult to clearly establish the specific role of chemicals such as PCBs in health of aquatic organisms. Niimi (1996) lists a number of field studies that indicate adverse effects in aquatic organisms, including reproduction, histological effects, biochemical changes and population changes. Most of these effects were correlated with concentrations greater than 2 mg/kg, which is the US and Canadian guideline level for consumable products for protection of human health (Niimi 1996).

Jarvinen and Ankley (1999) report data on tissue residues and effects for over 20 PCBs for 12 freshwater species and 12 marine species. It is not possible to summarise the data here but readers are referred to that publication for more information.

Laboratory studies on aquatic organism indicate that PCBs can cause adverse effects at low µg/L concentrations in water and at tissue concentrations at the low mg/L level (Niimi 1996). However, the concentrations that caused adverse effects on growth and reproduction in laboratory studies were generally higher than those in natural systems and about 100-fold higher than those reported to cause reproductive effects for comparable field organisms (Niimi 1996).

PCB tissue concentrations that may cause adverse effects on survival, growth and reproduction in macroinvertebrates were greater than 25 mg/kg. The corresponding concentrations in fish were > 100 mg/kg (Niimi 1996).

Guidelines based on bioaccumulation

The USEPA (1997a) promulgated water quality guidance for PCBs in the Great Lakes, incorporating bioaccumulation factors (BAF) based on Oliver and Niimi (1988), with recent modifications to derive a composite baseline factor. This uses the sum of the concentrations of all PCB congeners in animal tissue and the sum of the concentrations of all congeners in the ambient water to calculate BAFs at each trophic level. For the trophic level including salmonids, the BAF was 3.6 x 10⁶ and for the level including sculpins and alewife, 1.14 x 10⁶. This resulted in wildlife guidelines for PCB of 7.4 x 10^-5 µg/L to 1.2 x 10^-4 µg/L. Sediment is a significant gink for PCBs in water bodies and may be a source for biological contamination.

Guidelines

References

ANZECC & ARMCANZ 2000. Australian and New Zealand Guidelines for Fresh and Marine Water Quality, Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand, Canberra.

Bidleman TF, Patton GW, Walla MD, Hargrave BT, Vass WP, Erickson P, Fowler B, Scott V & Gregor DJ 1989. Toxaphene and other organochlorines in Arctic Ocean fauna: Evidence for atmospheric delivery. Arctic 42, 307–313.

CCREM 1987. Canadian water quality guidelines. Canadian Council of Resource and Environment Ministers, Ontario.

Coristine S, Haffner GD, Ciborowski JJH, Lazar R, Nanni ME & Metcalfe CD 1996. Elimination rates of selected di-ortho, mono-ortho and non-ortho substituted polychlorinated biphenyls in rainbow trout (Oncorhynchus mykiss). Environmental Toxicology and Chemistry 15, 1382-1387.

Farrugia AJ 1988. Assessment of polychlorinated biphenyl (PCB) wastes. Assessment report 88/1, State Pollution Control Commission, Sydney.

Hawker DW & Connell DW 1988. Octanol-water partition coefficients of polychlorinated biphenyl congeners. Environmental Science and Technology 22, 382-387.

HSDB (Hazardous Substances Data Bank) 1996. Micromedex Inc. 31 July 1996.

Jarvinen A W & Ankley G T 1999. Linkage of effects to tissue residues: Development of a comprehensive database for aquatic organisms exposed to inorganic and organic chemicals. SETAC Technical Publication Series, SETAC Press, Pensacola FL.

Kannan N, Tanabe S & Tatsukawa R 1989. Persistency of highly toxic coplanar PCBs in aquatic ecosystems: Uptake and release kinetics of coplanar PCBs in green-lipped mussels (Perna viridis Linnaeus). Environmental Pollution 56, 65-76.

Lincoln-Smith MP & Mann RA 1989. Bioaccumulation in nearshore marine organisms. II. Organochlorine compounds in red morwong Cheilodactylus fuscus around Sydney’s three major ocean outfalls. State Pollution Control Commission, Sydney.

Niimi AJ 1996. PCBs in aquatic organisms. Chapter 5 in Environmental contaminants in wildlife: Interpreting tissue concentations, eds WN Beyer, GH Heinz & AW Redmon-Norwood. SETAC Special Publication Series. CRC Press, Lewis Publishers, Boca Rato

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NSW EPA 2000. Analytical Chemistry Section, Table of Trigger Values 20 March 2000, LD33/11, Lidcombe, NSW.

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Scribner EA, Frederickson S, Kastl A, McDougal KW, Moodie LG & Williams RJ 1987. Organochlorine pesticide and polychlorinated biphenyl (PCB) residues in fish and other aquatic organisms in New South Wales. Part II. Marine and estuarine waters. Department of Agriculture, Sydney, NSW.

Sericano JL, Wade TL, El-Husseini AM & Brooks JM 1992. Environmental significance of the uptake and depuration of planar PCB congeners by the American oyster Crassostrea virginica. Marine Pollution Bulletin 24, 537-543.

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Tanabe S, Iwata H & Tatsukawa R 1994. Global contamination by persistent organochlorines and their ecotoxicological impact on marine mammals. Science of the Total Environment 154, 163-177.

Thompson GB, Chapman JC & Richardson BJ 1992. Disposal of hazardous wastes in Australia: Implications for marine pollution. Marine Pollution Bulletin 25, 155-162.

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