154
chlorpyrifos) and (Barrett et al., 2000). An overview of the lowest values of prolonged
acute toxicity of chlorpyrifos-ethyl for aquatic organisms is shown in Table 52. Up to
now, no data is available on the chronic toxicity of chlorpyrifos to organisms in the
marine environment which are exposed to low concentrations for several years.
Table 52: Survey of lowest value of prolonged toxicity of chlorpyrifos-ethyl to aquatic organisms.
Aquatic organism
Species
Value/period [d]
Cone. [pg/L]
Algae
Scene demus subspicatus
NOEC/4
27.5
Crustacean
Mysidopsis bahia
NOEC/35
0.005
Fish
Pimephales promelas
NOEC/30
0.012
Data from: (Data sheet on chlorpyrifos-ethyl)
Environmental concentrations of chlorpyrifos-ethyl in different environmental samples
are shown in Table 53. Concentrations on the order of of 0.4-0.9 ng/L have been found
in rain water (TNO rapport, 2002). A detailed estimation of chlorpyrifos-ethyl
deposition in surface and ground water is provided in a drinking water assessment by
the environmental fate and effects division (Barrett, 1998). A study by the National
Oceanic and Atmospheric Administration (Johnson et al., 1999) yields data on
chlorpyrifos-ethyl concentrations in marine sediments and marine biota (Table 53).
Table 53: Overview of chlorpyrifos-ethyl concentrations in water samples, sediments, and biota.
Sample
Sampling
location
Sampling date
Concentration
[ng/L]/[pg/kg dry
wt]
Limit of
detection [pg/kg]
Rain water
Netherlands
2000/2001
0.9/0.4 a
-
Surface water
US
1995
130 c
4
Ground water
US
1998
36 c
4
Marine sediment
US
1994-1997
0.84-5.68 d
0.25
Mussel tissue
US
1994-1997
4.18-52.92 d
0.25
Data from: a (TNO rapport 2002), c (Barrett, 1998), d (Johnson et al., 1999)
The major route of dissipation appears to be a slow aerobic and anaerobic degradation
and photolytic degradation in soil to 3,5,6-trichloro-2-pyridinol (TCPy)(Figure 24) as
