Biota bioaccumulation

The toxicological or cumulative effect of illicit drugs on the ecosystems has not been studied yet. Moreover, their fate and transport in the environment is to a big extent still unknown. Due to their physical-chemical properties (octanol-water partition coefficient, solubility, etc.) some of them, such as cannabinoids, are likely to bioaccumulate in organisms or concentrate in sediments whereas the rest, much more polar compounds, will tend to stay in aqueous environmental matrices. However, continuous exposure of aquatic organisms to low aquatic concentrations of these substances, some of them still biologically active (e.g., cocaine (CO), morphine (MOR) and MDMA) may cause undesirable effects on the biota. 

El-Nady, F.E. and Atta, M.M., Toxicity and bioaccumulation of heavy metals to some marine biota from the Egyptian coastal wasters, Journal of Environment Science and Health, A-31 (7), 1529-1545, 1996. 

The bioconcentration factor, although usually related to fish is actually an estimate of the bioaccumulation potential for biota in general. Different organisms may bioconcentrate a given chemical to a lesser or greater degree, however with different chemicals, the relative ranking with respect to bioconcentration will be essentially the same for all species. 

Consequently, Europe has historically been a hotspot of environmental pressures because of the contamination caused by agricultural, municipal, and industrial activities and high population densities [5, 6], Such contamination has led to poor water quality in many European river basins [7-12], In addition, this pollution can cause the accumulation in river sediments of toxic compounds such as pesticides [13], surfactants [14], and alkyl polycyclic aromatic hydrocarbons (PAHs) [15], These can in turn act as a source to biota [16] and as a potential risk for entire ecosystems [17] if the compounds bioaccumulate, and thereby enter the food chain [18],... 

Similar to other POPs, BFRs (except TBBPA) appear to be lipophilic and bioaccumulate in biota and humans [5], A considerable number of studies of PBDEs in wildlife have been undertaken since the mid-1980s, when Jansson et al. [6] first indicated that these compounds were present in samples collected remote from local sources and so may have become ubiquitous environmental contaminants [7, 8]. 

There is some discussion of how bioavailable and bioaccumulative BDE-209 is. Moreover, there is still a concern that BDE-209 may debrominate in the environment to form less-brominated BDE congeners which are more bioavailable than BDE-209 itself. A preliminary study on uptake and debromination of BDE-209 in caged rainbow trout following dietary exposure [9] showed a slow but measurable uptake of BDE-209 and the presence of lower brominated PBDEs. BDE-209 has been found generally linked to sediments, but some recent studies also reported low levels of this compound in aquatic biota samples from some locations in Europe [10-12] and from Japan [13]. 

In all cases, the concentrations of malathion and fenitrothion measured in water (up to 5.8 and 1.2 pg/L, respectively) were below the LC50 (lethal concentration 50%) values reported for these compounds in oysters and mussels, which range between 2.7 and 278 mg/L in the case of malathion, and between 10.3 pg/L and 123 mg/L in the case of fenitrothion (http //www.pesticideinfo.org). However, it has to be stressed that these LC50 values express acute toxicity, that both malathion and fenitrothion might be bioaccumulated by molluscs (as their detection in biota suggests), and that aquatic organisms are exposed to a variety of contaminants, some of which could show synergetic or additive effects [40]. Further matters of... 

Pentachlorophenol was found at high concentrations in all samples of sediments, waters, and biota collected near industrial facilities that used PCP as a wood preservative (Niimi and Cho 1983 Oikari and Kukkonen 1988) (Table 23.3). Fish can bioconcentrate PCP from water up to 10,000 times (Fox and Joshi 1984). However, similar concentrations were measured in blue mussel, Mytilus edulis (Folke and Birklund 1986), and softshell clam, Mya arenaria (Butte et al. 1985), from the vicinity of PCP-contaminated wastewater discharges as well as from more distant collection sites. Thus, PCP bioaccumulation in marine bivalve molluscs does not appear to be dose related. 

Most marine mammals are exposed to relatively high concentrations of those contaminants considered to be persistent (do not breakdown readily in the environment), bioaccumulative (are not readily metabolized and excreted by biota in aquatic food webs), and (immuno)toxic. Candidates in this category include various congeners of... 

The dominant transport process from water is volatilization. Based on mathematical models developed by the EPA, the half-life for M-hexane in bodies of water with any degree of turbulent mixing (e.g., rivers) would be less than 3 hours. For standing bodies of water (e.g., small ponds), a half-life no longer than one week (6.8 days) is estimated (ASTER 1995 EPA 1987a). Based on the log octanol/water partition coefficient (i.e., log[Kow]) and the estimated log sorption coefficient (i.e., log[Koc]) (see Table 3-2), ii-hexane is not expected to become concentrated in biota (Swann et al. 1983). A calculated bioconcentration factor (BCF) of 453 for a fathead minnow (ASTER 1995) further suggests a low potential for -hcxanc to bioconcentrate or bioaccumulate in trophic food chains. 

The chlorinated chemicals assessed do not have the same risk profile. For the more volatile chemicals the safety margins between the actual exposure and the level at which no effect on the environment would be expected is quite high. For more persistent chemicals there is a need to look to the environmental compartment where they can be accumulated (mainly in sediments and biota). For some of these chemicals the safety margin is quite low and in worst-case situations serious effects may occur. For the very persistent, bioaccumulative and toxic chemicals (like dioxins, PCBs and DDT), acceptable environmental concentrations are so low and difficult to control that the industry is committed to reducing as far as possible releases to the environment through application of Best Available Techniques (BAT), mainly with respect to dioxins. For other chemicals (PCBs, DDT), production has already been halted for some years. 

Hargrave, B.T., Phillips, G.A., Vass. W.P.. Bruecker. P.. Welch. H.E.. and Siferd. T.D. Seasonality in bioaccumulation of organochlorines in lower tropic level arctic marine biota. Environ. Sci. Technol, 34(6) 980-987. 2000. 

Evaluating Bioaccumulation Disequilibrium - Example Biota-Sediment Accumulation Factors... 

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