198 
Sorption to sediments does not lead to a significant enrichment in the sediments 
investigated. The estimated “enrichment” of endosulfan in sediment as compared to the 
water phase is about 820 (Figure 44). This means that sediment is not a major sink for 
this compound and will not be a good monitoring matrix. The low values are 
remarkable but can be explained by the intermediate polarity (log Kow 3.8 - 4.7) and a 
relatively rapid degradation (e.g. Helm et al., 2002 : half-life of endosulfan I : 0.046 - 
0.14 y). 
Compared to the classical pollutants, concentrations in sediment are low. At KS 11, for 
example, HCH isomer concentrations range from 10 to 200 ng/kg. Levels of the more 
lipophilic DDD and CB153 range from 1000 to 5000 ng/kg. PAH like, e.g., BaP shows 
sediment concentrations of 40 to 240 pg/kg (BSH, 2005). 
The bioaccumulation potential of endosulfan becomes apparent when comparing 
concentrations in the three compartments investigated (Figure 44). The estimated 
“enrichment” of endosulfan in biota as compared to the water phase is about 17600 
based on wet weight, and 76000 based on lipid weight. 
The observed endosulfan levels are comparable to those of classical pollutants like HCH 
and HCB, but are below the concentrations of the more lipophilic DDT and PCB group. 
Typical HCH concentrations in the German Bight ranged from 0.2 to 0.6 pg/kg ww in 
2000; HCB had a median of 0.84 pg/kg ww, and the sum of DDTs had a median of 3.7 
pg/kg ww (BSH, 2005). 
The results from the North and Baltic Seas are well explained by known endosulfan use 
in Europe. According to the background paper on endosulfan issued by the OSPAR 
Commission (OSPAR, 2002), endosulfan is used mainly in the south of Europe (1999: 
469.3 t/a), while in 1999 only 38.1 t/a was used in the countries bordering the North Sea 
and Baltic Sea. In most north European countries, endosulfan has not been used any 
more since the mid-1990s. Only Belgium, France, and Switzerland reported applications 
in 1999.