Environmental Engineering Reference
In-Depth Information
remained below the acceptable daily intake (ADI) value of 3.2, or 1.6 ng g
-1
(Japan).
In summary, the contamination of marine waters is still widespread, al-
though decreasing slowly in countries that implemented regulations. How-
ever, no significant decreases were noted in sediments and biota collected
over a long period of time. Organotins are also widespread in marine sys-
tems in developing countries. Of particular importance is the contamination
of biota, of which molluscs have the highest burdens, and sediments which
may act as reservoirs.
4.4
Bioaccumulation
TBT is rapidly taken up from low ambient levels and accumulated to rela-
tively high concentrations in organisms. BCFs range from 200 in some fish
up to 50 000 in marine invertebrates, but in general, BCFs range from 1000-
20 000 [4]. Molluscs show highest accumulation; the BCFs of TBT and TPT
were in the range of 1.2-6.6
10
4
. Bioaccumulation is dependent on ambient
pH and DOM (Fig. 2). In
Chironomus
larvae, BCFs varied at pH 5 and pH 8 be-
tween 140 and 900 for TBT, and 2200 and 2680 for TPT [25, 123], confirming
our previous results with
Daphnia
[22, 23].
TBT distributes differently into tissues, generally lipid-rich tissue are char-
acterized by highest burdens. In fish highest TBT residues occur in the liver
and peritoneal fat [4]. BCFs are in the range of 200-9400 in whole fish or mus-
cle tissue, but higher in viscera (1000-10 000) [4, 124]. The bioaccumulation
of TPT is in a similar range with BCF of 2000-3000 in liver, and 100-250 in
muscle. The very high levels of butyltins in the range from 44-7700 ng g
-1
(Sn) found in marine mammals in the Baltic Sea [57], Asia and the Pa-
cific [74], USA [68], and the Mediterranean [109] indicate a high bioaccumu-
lation.
Several studies focused on the question, whether or not biomagnification
of TBT or TPT takes place in food webs. All data indicate that TBT shows
no relevant biomagnification in aquatic ecosystems [4, 63, 75]. This holds true
for TPT to a lesser extent, as some minor biomagnification was indicated in
a freshwater lake foodweb [80]. If biomagnification takes place at all, it is only
minor. However, it must be stated that organotin bioaccumulation in food
webs is not well understood [74].
×
5
Ecotoxicological Effects
Organic derivatives of tin are by far more toxic than inorganic tin, and
the toxicity of organotins increases with progressive introduction of organic
