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EC number: 267-956-0
CAS number: 67953-76-8
Table 1: Effect of D2010 on growth and survival of D. magna
after 28 days (average of 4 replicates).
Nominal concentrations (mg/L as active acid)
Mortality of parents
Cumulative number of offspring
No. Alive (± SE)
4.3 ± 1.0
0.75 ± 0.5
3.2 ± 0.9
4.5 ± 0.5
4.2 ± 0.1
Result expressed as nominal concentration. Properties of the
test substance and evidence from other studies where concentrations were
measured indicate that nominal and
measured concentrations are likely to be in good agreement.
Not enough information is reported on water quality, however the
frequency of water renewal suggests the parameters to be in acceptable
The standard error associated with the
number of offspring has been reported for each observation in time.
However, it is not possible to add standard errors for each observation
time. Therefore due to the table format (cumulative # of offspring) and
lack of raw data the standard error is not reported. The standard errors
are very large and vary from 0.2 to 25. Given that the standard errors
of the data at each point are large, it is unlikely that number of
offspring in the control and the 3.37 and 6.75 mg/L treatments would
have been significantly different.
The total average number of offspring does
differ between the control, 3.37 and 6.75 mg/L concentrations.
Nevertheless, when the values have been compared at a each observation
stage of the study (day of offspring count) taking into consideration
the standard error, the number of offspring produced at each stage
between the control, the 3.37 mg/L and the 6.75 mg/L overlaps. This is
true for all observations but the last one at day 28. Should the raw
data have been available it would have been possible to make a more
definitive evaluation. Therefore the NOEC is considered to be 6.75 mg/L.
28-day NOEC 6.75 mg active acid/L, Daphnia magna, read-across
96-hour (sublethal) EC50 130 mg active acid/L, Crassostrea
virginica, read-across from HEDP-H.
A reliable 28-day NOEC value of
6.75 mg active acid/L has been determined for the effects of HEDP-H on
adult mortality and offspring production of the freshwater invertebrate
Daphnia magna (Monsanto, 1976). The study reflects the lowest
value that is available for this endpoint.
A long-term toxicity study of
non-assignable reliability is available with HEDP (2-3Na) to D. magna
(Henkel, 1984). However,
the pattern of mortality and offspring production is erratic and the
dose response curve is unusual. It appears that the concentration
of the test substance or bioavailability of essential nutrients (Ca) may
have posed a problem in the test; however it
was not possible to determine the causes of this, as the study provides
an insufficient level of detail. Therefore, the study has not been
included in the assessment.
Additionally, a sub-chronic
study with the eastern oyster Crassostrea virginica with HEDP-H
is available (EG&G, 1977). This is a reliable study and also a sensitive
endpoint (shell growth), determining a 96-hour EC50 (reported
as LC50) value of 130 mg active acid/L (reported as 81 ppm
(equivalent to 81 mg/l), the value has been converted taking into
consideration the density of the test substance).
Lastly, a 28-day NOEC value of
>12 mg/L was determined for the effects of HEDP-4Na on Daphnia
magna in a reliable study (Gledhill and Feijtel, 1992).
The acid, sodium and potassium salts in the HEDP category are freely
soluble in water and, therefore, the HEDP anion is fully dissociated
from its sodium or potassium cations when in solution. Under any given
conditions, the degree of ionisation of the HEDP species is determined
by the pH of the solution. At a specific pH, the degree of ionisation is
the same regardless of whether the starting material was HEDP-H, HEDP
(1-2Na), HEDP (2-3Na), HEDP-4Na, HEDP-xK or another salt of HEDP.
Therefore, when a salt of HEDP is introduced into test media or the
environment, the following is present (separately):
In this context, for the purpose of this assessment, read-across of data
within the HEDP Category is considered to be valid.
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