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somewhat contradictory to the well-described high affinity of chlorpyrifos to soil 
(Wauchope et al., 1992, Dabrowski et al., 2002, Racke, 1992). 
Concentrations in sea water were found to be well below the levels of acute toxicity 
reported for aquatic organisms, which range from 3 to 806 pg/L (U.S. environmental 
Protection Agency, 1986). However, Owen et al. (2002) reported inhibition of 
hemolymph acetylcholinesterase activity in a tropical scallop with chlorpyrifos levels as 
low as 0.1 to 10 ng/L, which is closer to the observed concentrations. 
Compared to the EQS value of 30 ng/L, as proposed for evaluating inland and 
transitional waters for the WFD, the observed sea water concentrations for chlorpyrifos 
are quite low. 
Considering the short half-life and volatility of the substance and the low levels of local 
sources, it is remarkable that chlorpyrifos has been detected in the marine environment 
of the North and Baltic Seas at all. In water, concentrations of chlorpyrifos-ethyl are 
higher than those of the classical lipophilic pollutants such as HCB, DDT, PCB or 
PAHs, but below HCH concentrations. In sediments and biota, concentrations are below 
the levels of classical pollutants. 
Unfortunately, it has not been possible to obtain detailed production or consumption 
data for Germany or Europe. An evaluation of the findings regarding impacts on the 
marine environment is difficult as long as figures on chlorpyrifos consumption in the 
states bordering the North Sea and Baltic Sea are not available for comparison with 
substance levels found in the sea. According to pan-uk (2005), in Europe about 1000 t is 
used annually. Thus, chlorpyrifos does not play the same important role in Europe as it 
does in the US, where an estimated 10000 t is used annually (EPA at 
www.epa.gov/oppsrrdl/op/chlorpvrifos/summarv.htm). 
As a consequence of the positive findings, the BSH will determine chlorpyrifos on a 
voluntary basis during the next two years in order to support the results of this study. 
However, because of the low absolute concentrations it is not considered necessary to 
include chlorpyrifos as a routine parameter in the standard monitoring program.