ANNEX 7: CONCENTRATIONS OF TRIS (4-CHLOROPHENYL) METHANOL AND TRIS (4-CHLOROPHENYL) METHANE IN FISH

Tris(4-chlorophenyl)methanol (TCPM) and tris(4-chlorophenyl)methane (TCPMe) were determined in fish samples from Europe and Eastern Canada. TCPM and TCPMe were found in most of the samples analysed. Levels of TCPM were generally higher than those of TCPMe, resulting in average TCPM/Me ratios > 1. Differences in TCPM/Me ratios could be due to differences in the proximity of the various sources, in the trophic levels of the fish and to the presence of interferences in analytical methods. We suggest that an interlaboratory validation study be conducted to improve our ability to compare results from different laboratories and geographic regions. Introduction Tris(4-chlorophenyl)methanol(TCPM) and tris(4-chlorophenyl)methane (TCPMe) are among the newest persistent organic pollutants (POPs) reported in environmental samples. TCPM was first found in marine mammals in the late 1980s (Walker et al., 1989). Soon after, the presence of TCPM was reported, along with the qualitative presence of its presumed precursor, TCPMe, in both marine mammals and birds (Zook et al., 1992; Jarman et al., 1992). These two compounds were then quantified in sediments, fish, marine mammals and human milk (Rahman et al., 1993, de Boer et al., 1996; de Boer, 1997). Recent studies have confirmed that these compounds are ubiquitous in the marine environment and that they are bioaccumulated, since organisms at the top of the aquatic food chain, such as birds and mammals, have the highest reported levels (de Boer et al., 1996; Muir et al., 1996a, 1996b; Lebeuf et al., 1998; Falandysz et al., 1999; Minh et al., 1999; Watanabe et al., 1999; Lebeuf et al., 2000). Few data are available on the toxicity of these compounds. In rats, Poon et al. (1997) reported that short-term exposure to TCPM led to the induction of liver enzymes and resulted in higher spleen weights and elevated white blood cell and lymphocyte counts. Recently, Foster et al. (1999) demonstrated that TCPM modifies reproductive physiology in the male rat. There is clearly a need for more information on the toxicity of these compounds. The principal source of TCPM and TCPMe to the marine environment is unknown. These compounds may originate from a variety of sources including the production of synthetic high polymers and of light-fast dyes for acrylic fibres, and the manufacture of anthelminthic drugs (Jarman et al. 1992). Other potential sources include agrochemicals such as formulations of Dicofol and technical DDT, both of which contain structurally related compounds (Jarman et al., 1992). Walker et al. (1989) did not detect TCPM in technical formulations of DDT at a level above 0.1 %. More recently, Buser (1995) showed that, under conditions used in the synthesis of technical DDT, 10 TCPMe isomers were formed in small amounts. However, the link between Σ-TCP (TCPM and TCPMe) and technical DDT in environmental samples has not been clearly established. During the last few years, several members of the MCWG expressed an interest in studying these compounds. Following the initiative of the DLO-Netherlands Institute for Fisheries to distribute TCPM and TCPMe standards, several laboratories volunteered to set up an analytical method for these compounds and to collect data in various environmental samples. The present paper summarises the results obtained in fish samples specifically, and provides an overview of data reported in the scientific literature. The main objective of this paper is to compare the levels and ratios of TCPM/Me in various fish species from different areas in Europe and Canada. In addition, the relationship between Σ-TCP and Σ-DDT levels is assessed to verify the hypothesis that technical DDT is the main source of TCPMe in the marine environment.