Bisphenol A Accumulation in the Freshwater Clam Pisidium amnicum at Low Temperatures J. Heinonen, J. Honkanen, J. V. K. Kukkonen, I. J. Holopainen Department of Biology, Laboratory of Aquatic Ecology and Ecotoxicology, University of Joensuu, P.O. Box 111, FIN-80101, Joensuu, Finland Received: 10 July 2001 / Accepted: 4 February 2002 Abstract. Toxicokinetics of 14 C-labeled bisphenol A (BPA) was studied in the small freshwater clam Pisidium amnicum at four ecologically relevant low temperatures (2, 6, 8, and 12°C). The uptake clearance (k u ) of BPA increased from 1.49 to 6.55 ml  g -1  h -1 as temperature increased from 2 to 8°C but decreased slightly again at the highest temperature. The depu- ration of BPA was very slow and statistically insignificant at 2°C, but the depuration rate (k d ) increased linearly as temper- ature increased from 2 to 12°C. The longest half-life of BPA in clam tissues, 221 h, was found at the lowest temperature, and the highest bioconcentration factor of 144 was measured at 8°C. Data show that P. amnicum accumulates BPA so that the bioconcentration factor rises over 100 at each temperature tested. Further, the data demonstrate the importance of temper- ature on the processes that control both the uptake and elimi- nation of this compound. Bisphenol A (BPA) is an industrial chemical used in the production of polycarbonate and epoxy resins, flame retardants, and other specialty products. The acute toxicity of BPA to aquatic organisms is slight to moderate, bioconcentration fac- tors (BCFs) in fish range from 5 to 68, suggesting a low potential for bioaccumulation, and the half-lives of 2.5– 4.0 days indicate a rapid biodegradation in water (Staples et al. 1998). However, the validity of the properties given above is not known in cold boreal waters. Further, more data are needed about the toxicity and bioaccumulation of BPA in inverte- brates, especially in bivalves, as most of the current knowledge is obtained from fish. BPA is known to have estrogenic prop- erties in fish at low sublethal concentrations (e.g., Lindholst et al. 2000), which also stresses the need to study bioaccumula- tion. Estrogenic effects are reported in aquatic invertebrates as well (Andersen et al. 1999), but such studies are few, probably because the basic knowledge of the endocrinology in inverte- brates is poor in comparison with vertebrates (DeFur et al. 1999). The freshwater clam Pisidium amnicum is commonly found from shallow rivers and adjacent lake bottoms throughout Europe and northeastern America. P. amnicum in northern Europe is well adapted to low water tempera- tures; the clam population used in this study spends approx- imately 6 months in ice- and snow-covered water at tem- peratures of 0 – 4°C. Individuals are even found alive in frozen sediment (Olsson 1981; Holopainen 1987). Accumu- lation of BPA in Sphaeriid clams is not known, but, as an efficient filter feeder, P. amnicum has been shown to rapidly accumulate organic toxicants from water at different sea- sonal temperatures (Heinonen et al. 2000). Furthermore, studies in littoral enclosures receiving regularly another endocrine disrupter, 4-nonylphenol, have shown the Spha- eriid clams to be the most sensitive group in the benthic macroinvertebrate community used (Schmude et al. 1999). Water temperature is one of the natural factors that affect the accumulation and elimination of chemicals, mainly by chang- ing physiology of the organisms. However, for both amphipods (Landrum 1988) and clams (Heinonen et al. 2000), the effect of temperature seems to become weaker in chemicals with de- creasing hydrophobicity. Seasonal variation in reproductive condition may also affect the kinetic processes in many aquatic organisms (Landrum et al. 1992). Seasonal variation in meta- bolic rates of the ovoviviparous Sphaeriidae clams may be partially independent of temperature but show increasing me- tabolism during the times of growth and reproduction (Way and Wissing 1984). First-order rate coefficient models are commonly used to model toxicokinetics of waterborne chemicals. In this study the toxicokinetics of BPA was studied in P. amnicum at four environmentally realistic temperatures. Experiments were per- formed in January to avoid the possible effects of active re- production and growth on respiration and hence on kinetics. The general objective was to study the effects of temperature on toxicokinetics of a chemical with low hydrophobicity (log K ow of BPA is 3.40). A more specific goal was to determine the potential of BPA to bioaccumulate in clams at the low temper- atures typically found in their habitat. This kind of knowledge is needed in the ecological risk assessment in boreal waters. The kinetic parameters for clams are compared to those mea- sured for salmon (Salmo salar) eggs under identical exposure conditions (Honkanen et al. 2001). Correspondence to: J. Heinonen; email: Jari.Heinonen@joensuu.fi Arch. Environ. Contam. Toxicol. 43, 50 –55 (2002) DOI: 10.1007/s00244-002-1146-y ARCHIVES OF Environmental Contamination and T oxicology © 2002 Springer-Verlag New York Inc.