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REGULATORY

TOXICOLOGY

AND

PHARMACOLOGY

6, 1 l-23 (1986)

Evaluation of Acute Bioassays for Assessing Toxicity of Polychlorinated Biphenyl-Contaminated Soils Jo ELLEN HOSE,’ VANTUNA

Research

LINDAA.BARLOW,ANDSTANBENT

Group, Moore Laboratory Los Angeles, California

A. A.ELSEEWI,MARKCLIATH, Program

of Excellence

in Energy

Research.

of Zoology, 90041

Occidental

ANDMARGARET University

of California.

College.

RESKETO Riverside,

California

92521

AND COLLEEN Research

and Development,

Southern

Received

DOYLE

California

Edison,

Rosemead,

California

91770

July 30, 1985

Proposed State of California regulations use fish toxicity information as one criterion in municipal or industrial waste hazard evaluation. Static 96-hr bioassayswere performed using fathead minnows (Pimephales promelas), blacksmith (Chromis punctipinnis), and glass shrimp (Palaemonetes kadiakensis) exposed to soil experimentally contaminated with up to 500 ppm polychlorinated biphenyl (PCB) capacitor fluid added at a concentration of 500 mg liter-‘. Other bioassays were conducted with a 6-day mixing period prior to the bioassay or with acetone added to solubilize the PCBs. No mortality attributable to PCB toxicity was observed in definitive bioassays using the two fish and one invertebrate species. PCB levels leached from soil containing 500 ppm Aroclor 1242 ranged from ~0.6 to 3.4 ppb in freshwater tests to 3.5 ppb in seawater bioassays. Using these data as the basis for waste classification, soils contaminated with up to 500 ppb PCBs during capacitor spills would be designated nonhazardous. PCBs are known to be environmentally persistent and to bioaccumulate. Acute toxicity tests, therefore, do not adequately evaluate the general toxicity of PCB-contaminated soils. Hazardous waste regulations for hydrophobic compounds such as PCBs should instead be based upon chronic toxicity data and should also consider bioaccumulation potential. 0 1986 Academic press, Inc.

INTRODUCTION

Polychlorinated biphenyls (PCBs) are extensively used by electric power utilities as insulation in transformers and capacitors becauseof their excellent fireproof and di’ To whom correspondence should be sent. 11 0273-2300186 $3.00 Copyright 0 1986 by Academic Press, Inc. All rights of reproduction in any form reserved.

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HOSE

ET

AL.

electric properties. Despite their use in closed systems, PCBs continue to enter the environment through accidental fires and spills, transportation spills, and leakage from obsolete equipment in landfills. Because PCBs are bioaccumulative, environmentally persistent, and potentially toxic, state and federal guidelines have been promulgated for the handling and disposal of PCB-contaminated wastes. Of these, the California Assessment Manual (CAM) for hazardous wastes proposed by the California Department of Health Services (1983) details a number of criteria by which a PCB-contaminated waste would be designated as hazardous. Some of these criteria are based on fish toxicity information; in particular, the soluble threshold limit concentration (STLC) of 5 ppm PCB and the total threshold limit concentration (TTLC) of 50 ppm. PCBcontaminated soils or leachates exceeding the TTLC or STLC values, respectively, would be considered hazardous on the basis of PCB concentration alone. Using the proposed 96hr aquatic bioassay method, soil with 96-hr L& values of ~500 mg liter-’ would be classified as hazardous. Waste classifications are then to be used to determine the method and location of waste disposal. In view of the estimated 17 million pounds of PCB-contaminated wastes entering landfills which were generated by phasing out of PCB equipment (Mackay et al., 1982) such regulations are of great importance to electric utilities’ waste management operations and to persons living near landfill sites. On first examination, the fish bioassay test would appear to be a useful indicator of environmental toxicity since a PCB waste or PCB residues leached from the waste could enter adjacent streams. There are, however, problems in using results of a shortterm bioassay to predict the environmental toxicity of hydrophobic, persistent compounds such as PCBs. The STLC of 5 ppm PCBs, which is based upon a 30-day LCsO of 0.05 ppm for rainbow trout (Mayer et al.. 1977) and an attenuation factor of 100, cannot be attained in an aqueous system without the use of solvents to increase PCB solubility from the solubility limit of approximately 56 ppb (Haque et al., 1974). Most published bioassays use solvents such as acetone to achieve PCB concentrations high enough to produce toxicity. In the CAM aquatic bioassay protocol (Department of Health Services, 1983) fish would be exposed to wastes in solution or suspension for 96 hr without the use of solvents. Few investigators have tested PCB-contaminated soils for toxicity using this direct method. In one such experiment, Nimmo et al. (197 1) found that soil containing 6 1 ppm Aroclor 1254 was not toxic to the shrimp, Penaeus duorurum, or crab, Ucu minux. Thus, the proposed CAM protocol may not adequately assay the toxicity of soils contaminated with PCBs. The objective of the research described here is to critically evaluate the aquatic bioassay proposed in the CAM (Department of Health Services, 1983) as a method of assessing the toxicity of soils contaminated with PCB capacitor fluid. Definitive bioassays were conducted with a freshwater and a marine fish species, fathead minnow (Pimephales promelas) and blacksmith (Chromis punctipinnis), respectively, using a California soil experimentally contaminated with Line Material Industries capacitor fluid (Aroclor 1242). Nominal PCB concentrations in soils were compared to actual levels of soluble PCBs. Results of other bioassays performed using modifications of the CAM procedure are presented. Also, bioassays were conducted with an invertebrate, glass shrimp (Palaemonetes kadiukensis), reported to be more sensitive to PCB toxicity than are fishes (Johnson and Finley, 1980).

PCB TOXICITY

MATERIALS Experimental

AND

TESTING

13

METHODS

System

Tests were conducted in wooden-frame enclosures which supported two fiberglass troughs and which were covered with 12-mm-thick polyvinyl chloride (PVC) sheeting. Each enclosure had its own lighting system which consisted of two Vitalite bulbs per fiberglass trough. The photoperiod was 12 hr light and 12 hr dark. Enclosures were connected to a continuous exhaust system. The enclosures received air from a central area air compressor which was delivered to individual aquaria via PVC piping and flexible PVC air tubing. Each enclosure was fitted with a YSI Model 47 telethermometer with 12 probes for remote temperature sensing during bioassays. Fresh water for bioassays was obtained by softening Redondo Beach, California, city water in a Culligan Mark 59 automatic water conditioner followed by ultraviolet sterilization in an Aquafine Model SL- 1 sterilizer. This softened water had < 16 ppb residual chlorine, 232 and Finley

(1980).

TROUT

HOSE ET AL.

20

TABLE

5

RELATIVE SENSITIVITY OF FISH AND INVERTEBRATESTO AROCLORS 1242 AND 1254 Aroclor formulation

Go (ppb)

Test organism

1242

Rainbow trout Bluegill Amphipod (Gammarus pseudolimnaeus) Crayfish (Oronectes nais)

1254

Rainbow trout Bluegill Glass shrimp Amphipod (G. pseudolimnaeus) Crayfish (0. nais)

Conditions

61 125 10 30

5-day, flow-through 5-day. flow-through 4-day, flow-through T-day

142 2740 3 2400 100

5-day, flow-through 4-day 7-day, flow-through 4day 4-day

Note. Data are from Johnson and Finley (1980).

Using sediment with 500 ppm Aroclor 1254, Halter and Johnson (1977) measured PCB water levels of 0.6 ppb at time 0 and 7.6 ppb at equilibrium (Day 8). Water used in their tests was hard (329 ppm CaC03) and temperatures were slightly lower. According to CAM specifications, a maximum soil concentration of 500 mg dry weight liter-’ was used while in Halter and Johnson’s experiment 66.7 g liter-’ was tested. The much higher soil concentration in their study was probably responsible for the higher dissolved PCB levels but it is important to note that this produced only a relatively slight increase in dissolved PCB levels. Our results shown that soluble PCB concentrations generated during the seawater bioasssay were similar to those measured during freshwater tests. Some of the PCB soil burdens used in this study (50 to 100 ppm dry weight) are representative of those found in polluted aquatic environments (Table 6). Point estimates of PCB concentrations in Hudson River sediments, the most contaminated water system in the Atlantic area, reach 140 ppm (NAS, 1979). The higher concentrations of 250 and 500 ppm PCBs which were tested are levels which may be present following spillage of PCB transformer or capicitor fluid on land. Mackay et al. ( 1982) estimated that PCB levels following a spill would reach a concentration of a few percent TABLE

6

REPRESENTATIVEENVIRONMENTAL LEVELS OF PCBs IN WATER AND AQUATIC SEDIMENTS Source

PCB concentration

Reference

Marine sediment, Florida Marine sediment, Santa Monica Bay Marine sediment, Meditemurean Sea Freshwater sediment, estimated mean Seawater, deep Mediterranean Sea Seawater, surface California Fresh water, Great Lakes Fresh water, estimated mean

61 ppm drywt 1.6 ppm wet wt O.lppmdrywt 0.06 ppm 0.8 x lo-’ ppb 1.1-5.9 ppb 0.8-37 ppb 1.I ppb

Nimmo et al., 197 1 Schafer et al., 1982 Fowler et al., 1978 Mackay et al., 1982 Elder et al., 1976 NAS, 1979 NAS, 1979 Mackay et al., 1982

PCB TOXICITY

TESTING

21

(1% equals 10,000 ppm). Dissolved PCB levels generated in this study of ~3.5 ppb represent levels commonly measured in California coastal waters during the early 1970s and in major U. S. rivers (Table 6). A 96-hr exposure of fathead minnows to soil PCB levels between 50 and 500 ppm, which would be designated nonhazardous using the CAM (Department of Health Services, 1983) aquatic bioassay criterion, resulted in tissue levels exceeding the recent U. S. Food and Drug Administration action limit of 2 ppm. These tissue concentrations are 2 to 10 times higher than those reported for minnows similarly exposed to Aroclor 1254 adsorbed onto soil (Halter and Johnson, 1977). Laboratory experiments using young striped bass (Morone saxatilis) have demonstrated that accumulation resulted in part from desorption of sediment-bound PCBs and that a dietary component is also involved (Califano et al., 1982; Pizza and O’Connor, 1983). Our observations that PCB tissue burdens in fathead minnows reach a threshold at soil concentrations of 2100 ppm and that dissolved PCBs are undetectable using sediment-bound PCB levels of 100 ppm suggest that direct exposure to contaminated particles is the more important. Halter and Johnson (1977) showed that direct contact to sediment-sorbed PCBs greatly enchances bioaccumulation and suggest that the typical fathead minnow behavior of substrate grazing was responsible for the unexplained increase. Our results underscore the need for caution in the routine application of mathematical models of toxicant bioconcentration without supporting observations on species-specific feeding and behavior patterns. While acute exposure to sediments containing 50 to 500 ppm Aroclor 1242 PCBs and to dissolved PCB concentrations of up to 3.5 ppb was not toxic to the animals tested, chronic toxic effects have been reported following exposure of aquatic biota to similar PCB levels (NAS, 1979). Exposure to sediment containing 30 ppm Aroclor 1254 for 90 days was lethal to marine worms (Fowler ef al., 1978). Reproduction and growth of fathead minnows was affected at concentrations of 2.2 ppb Aroclor 1248 and >1.8 ppb Aroclor 1254 (Nebeker et al., 1974). The low PCB residues leached from highly contaminated sediments may deleteriously affect long-term processes of aquatic organisms such as growth and reproduction. Jenkins et al. ( 1982) and Perkins et al. (1982) have reported that white croaker (GenyonevMus heatus), which live off Palos Verdes, California, an area characterized by high chlorinated organic hydrocarbon levels (sediment PCB concentrations up to 10.1 ppm), have liver changes which correlate with sediment chlorinated hydrocarbon concentrations. Using several of the CAM (Department of Health Services, 1983) criteria (bioaccumulation, environmental persistence, and a PCB concentration greater than the limit of 50 ppm TTLC), most of the soils tested would be classified as toxic. None, however, demonstrated acute toxicity using the CAM aquatic bioassay procedure with the suggested fish species. Moreover, several modifications which could be included in the procedure with a minimum of labor or expense (such as testing a reportedly more sensitive species or life history stage or increasing solubility by chemical or physical methods) did not alter the observed lack of toxicity. Many other environmentally significant pollutants such as high-molecular-weight petroleum hydrocarbons, organochlorine pesticides, and wood-preserving chemicals are by virtue of their chemical structure bioaccumulative and environmentally persistent like PCBs. More specific examples include aromatic hydrocarbons like anthracene and benzo[a]pyrene which are generated during the production of fossil and

22

HOSE ET AL.

synthetic fuels and pesticides or herbicides such as Kelthane, DDT, dieldrin, Mirex, and chlorophenols. These compounds possesshigh octanol:water partition coefficients, a measurement of hydrophobicity, as well as high soil adsorption coefficients (McCall et al., 1980). Thus, binding of these hydrophobic compounds to soils, particularly those of low organic carbon content, tends to mitigate toxicity since very low (usually ppb) levels of toxicant are leached from soils under environmental conditions and adsorbed compounds may also have reduced bioavailability (McCarthy, 1983). Many of these chemicals, for example, DDT and benzo[a]pyrene, have very low acute toxicity, and short-term tests such as the 96-hr fish bioassay described in the CAM (Department of Health Services, 1983) will not adequately evaluate their general toxicity. As in the case of PCB-contaminated soils, chronic toxicity testing appears to be a more realistic assessment of general toxicity of hydrophobic chemicals adsorbed onto soils. STLC and TTLC determinations proposed in the CAM could be more accurate predictors of general toxicity if limit values are based upon valid toxicity studies. CONCLUSIONS Toxicity information derived from static 96-hr aquatic bioassays do not provide an accurate assessment of the toxicity of hydrophobic compounds such as PCBs. Chronic toxicity studies and estimations of bioaccumulation potential appear to be more appropriate indictors of the toxicity of these compounds and hazardous waste regulations should be based upon these data. ACKNOWLEDGMENTS This work was supported by the Southern California Edison Company under Contract C-305-2903. Tissue PCB analysis was performed by Richard Gossett of the Southern California Coastal Water Research Project. We thank Waheedah Muhammad for typing the manuscript.

REFERENCES American Public Health Association (APHA) (1975). Standard Methods for the Examination of Water and Wastewater. 14th ed. APHA. CALIFANO, R. J., O’CONNOR, J. M., AND HERNANDEZ, J. A. (1982). Aquat. Toxicol. 2, 187-204. Department of Fish and Game (1976). Guidelines for Performing Static Acute Toxicity Fish Bioassays in Municipal and Industrial Wastewaters. State of California State Water Resources Control Board, Dept. of Fish and Game, Sacramento. Department of Health Services (1983). Criteria for ZdentiJcation of Hazardous and Extremely Hazardous Wastes: Proposed Revisions to Title 22. State of California Department of Health Services, Sacramento. Drill, Friess, Hayes, Loomis and Schaffer, Inc. (1982). Comments and Studies on the Use of Polychlorinated Biphenyls in Response to an Order of the U. S. Court ofAppeals for the District of Columbia Circuit, Vol. II, Potential Health purities. Arlington,

Eflects

in the Human

from

Exposure

to Polychlorinated

Biphenyls

and Related

Zm-

Va. ELDER, D. L., PARSI, P., AND HARVEY, G. R. (1976). Polychlorinated biphenyls in seawater, sediment and over ocean air of the Mediterranean. In Activities of the International Laboratory ofMarine Radioactivity, I976 Report, pp. 136- 151. International Atomic Energy Agency, Vienna. FOWLER, S. W., POLIKARPOV, G. G., ELDER, D. L., PARSI, P., AND VILLENEUVE, J.-P. (1978). Mar. Biol. 48, 303-309. HALTER, M. T., AND JOHNSON, H. E. (1977). A model system to study the desorption and biological

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TESTING

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availability of PCB in hydrosoils. In Aquatic Toxicology and Hazard Evaluation (F. L. Mayer and J. L. Hamelink, eds.), ASTM STP634, pp. 178-195. Amer. Sot. for Testing and Materials, Philadelphia. HAQUE, R., SCHMEDDING, D. W., AND FREED, V. H. (1974). Environ. Sci. Technol. 8, 139-142. HARVEY, G. R., AND STEINHAUER, G. W. (1976). Biogeochemistry of PCB and DDT in the North Atlantic. In Environmental Biogeochemistry Vol. 1, Carbon, Nitrogen, Phosphorus, S&r and Selenium Cycles (J. 0. Nriagu, ed.), pp. 203-22 1. Ann Arbor Science, Ann Arbor, Mich. JENKINS, K. D., BROWN, D. A., HERSHELMAN, G. P., AND MEYER, W. C. (1982). Contaminants in white croakers Genyonemus lineatus (Ayres, 1855) from the Southern California Bight. I. Trace metal detoxiIication/toxiIication. In Physiological Mechanisms of Marine Pollutant Toxicity (W. B. Vemberg et al., eds.), pp. 177- 195. Academic Press, New York. JOHNSON,W. W., AND FINLEY, M. T. (1980). Handbook ofAcute Toxicity of Chemicals to Fish and Aquatic Invertebrates: 196.5-1978,

Summaries

of Toxicity

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at Columbia

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Fish and Wildlife Service Resource Publ. 137. U. S. Dept. of the Interior, Washington, D. C. MACKAY, D., AND Institute for Environmental Studies (1982). Comments and Studies on the Use of Polychlorinated Biphenyls in Response to an Order of the U. S. Court of Appeals for the District of Columbia Circuit, Vol. IV, Environmental Pathways of Polychlorinated Biphenyls. University of Toronto, Toronto. MAYER, F. L., MEHRLE, P. M., AND SANDERS,H. 0. (1977). Arch. Environ. Contam. Toxicol. 5, 501-5 11.

MCCALL, P. J., SWANN, R. L., LASKOWSKI, D. A., UNGER, M., VRONA, S. A., AND DISBURGER, H. J. (1980). Bull. Environ. Contam. Toxicol. 24, 190-195. MCCARTHY, J. F. (1983). Arch. Environ. Contam. Toxicol. 12, 559-568. National Academy of Sciences (NAS) (1979). Polychlorinated Biphenyls. NEBEKER, A. V., PUGLISI, F. A., AND DEFOE, D. L. (1974). Trans. Amer. Fish. Sot., 562-568. NIMMO, D. R., WILSON, P. D., BLACKMAN, R. R., AND WILSON, A. J. (1971). Nature (London) 231, 5052.

PERKINS, E. M., BROWN, D. A., AND JENKINS, K. D. (I 982). Contaminants in white croakers Genyonemus linatus (Ayres, 1855) from the Southern California Bight. III. Histopathology. In Physiological Mechanisms of Marine Pollutant Toxicity (W. B. Vemberg et al., eds.), pp. 2 15-23 1. Academic Press, New York. PIZZA. J. C., AND O’CONNOR, J. M. (1983). Aquat. Toxicol. 3, 3 13-327. SCHAFER,H. A., HERSHELMAN, G. P., YOUNG, D. R., AND MEARNS, A. J. (1982). Contaminants in ocean food webs. In Coastal Water Research Project Biennial Report 1981-82 (W. Bascom, ed.), pp. 17-28. Southern California Coastal Water Research Project, Long Beach.