Entry into the marine environment
Azinphos-methyl is a broad spectrum, non-systemic,
organophosphorus insecticide and acaricide with
contact and stomach action. It is an inhibitor of
acetylcholinesterase (AChE). It is used for the
control of chewing and sucking insects in agriculture
Entry into the aquatic environment arise from accidental
spillages during transport, storage, use or bad
practice. Diffuse pollution sources include spray-drift
during application, agricultural run-off from treated
land and the waste disposal of azinphos-methyl products.
Recorded levels in the marine
Monitoring data from the National Rivers Authority
and the National Monitoring Programme Survey of
the Quality of UK Coastal Waters are presented in
Appendix D. One water column concentration was found
to exceed the EQS value in the NRA survey. However,
no details on the actual concentration or the reason
for exceedence are available. Monitoring data were
not available for sediments or biota.
The available data suggest that concentrations
of in UK coastal and estuarine waters are generally
unlikely to exceed relevant quality standards derived
for the protection of saltwater life.
Fate and behaviour in the marine
The fate and behaviour of azinphos-methyl was reviewed
by Jones et al (1996). Azinphos-methyl is
only sparingly soluble in water (14 mg l-1
at 15 °C) and the octanol/water partition coefficient
is moderate (log Kow = 2.99 to 3.77). Based on the
soil organic carbon sorption coefficient (log Koc
= 3.56), sorption on suspended solids and aquatic
sediments is likely.
Meyer (1965) applied azinphos-methyl WP directly
to a farm pond containing algal, plant and fish
life and calculated a half-life of approximately
Flint et al (1970, cited in US EPA 1986)
determined the half-life of Guthion (a formulation
containing azinphos-methyl) at 30 °C
in illuminated pond water and in phosphate buffer
protected from light in the laboratory. The half-life
in pond water was 1.2 days (pH 6.9), whereas that
in the buffer solution (pH 7) was 10 days. The more
rapid degradation in pond water was attributed to
the effect of sunlight and micro-organisms.
Effects on the marine environment
Toxicity to marine organisms
An exhaustive literature review on the toxicity
of azinphos-methyl to marine organisms has not been
carried out for the purposes of this profile. The
information provided in this section is taken from
existing review documents (Jones et al 1996).
The most sensitive groups of organisms have been
The toxicity of azinphos-methyl to aquatic organisms
was reviewed by Jones et al (1996). Few data
were available for marine organisms.
Jones et al (1996) concluded that crustaceans
were the most sensitive group of saltwater species.
For the European species pink shrimp Pandalus
montagui and brown shrimp Crangon crangon
48-hour LC50 values between 0.3 and 1 µg l-1
have been reported, whereas the cockle Cerastoderma
edule was the least sensitive species tested,
with a 48-hour LC50 greater than 10 mg l-1
(Portmann and Wilson 1971).
A number of acute LC50 values were reported for
fish species. For the threespined stickleback Gasterosteus
aculeatus, a 96-hour LC50 of 12.1 µg l-1
was obtained in slightly saline water (5 ppt)
and of 4.8 µg l-1 in water
with a salinity of 25 ppt (Katz 1961). Similar LC50s
of 8 µg l-1 (96-hour;
Lahav and Sarig 1969, cited in US EPA 1986) and
3.2 µg l-1 (48-hour; Mayer
1987) have been reported for the striped mullet
Mugil cephalus. The 24-hour LC50 for the
white mullet Mugil curema was found to be
5.5 µg l-1 (Butler 1963,
cited in US EPA 1986).
Inhibition of acetylcholinesterase (AChE) activity
and mortality caused by exposure to azinphos-methyl
was investigated by Coppage (1972) in a static test
in 4 ppt salinity using the sheepshead minnow Cyprinodon
variegatus as test species. After 48 hours exposure
greater than 80%, AChE inhibition and 40 to 60%
mortality were observed at 3.5 µg l-1.
After 120 hours exposure to 2 µg l-1
78%, AChE inhibition was observed but there were
In a partial life-cycle toxicity test on the sheepshead
minnow Cyprinodon variegatus (Cripe et
al 1984), significant reductions in egg numbers
from spawning adults were observed at 0.42 µg l-1.
No data could be located for sediment-dwelling
Jones et al (1996) found no reliable data
to quantify the bioaccumulation potential of azinphos-methyl
but, based on the octanol/water partition coefficient
(Log Kow 2.99-3.77), the authors concluded that
it is only likely to be moderate.
Potential effects on interest
features of European marine sites
Potential effects include:
- acute toxicity to invertebrates, in particular
crustacea, and fish at concentrations above the
EQS of 0.01 µg l-1 (annual
average) and 0.04 µg l-1
(maximum allowable concentration);
- accumulation in sediments and potential effects
on sediment dwelling organisms, although no data