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EC number: 211-334-3
CAS number: 638-38-0
Toxicity to algae: EC50 (10d) = ca. 34.5 mg/L Manganese (II) acetate for Plectomena boryanum (static, based on surviving colonies)
The relevant EC50 and EC10 values were
derived from the key study, which is the more relevant one. First, the
test duration is prolonged which gives in general a better insight in
the overall toxicity of a substance. Second, since here a "split-up"
approach was used to assess the overall toxicity of Manganese (II)
acetate, namely to assess both manganese cation and acetate anion
separately due to the available data, the acetate anion turned out to be
not harmful at all to aquatic algae (Toxicity Threshold of acetic acid =
4000 mg/L). Hence, the results for the manganese cation are the more
relevant ones for further risk assessment.
Although no standard guideline was
followed, two different strains of algae tested and the documentation
and given results indicate that the study was well-performed and
satisfies general scientific requirements. So the study is classified as
reliable with restrictions and consequently, the results can considered
to be reliable and used for classification. Since Plectonema boryanum is
the more sensitive species, these values are used for classification: An
EC50 value of approx. 0.2 mmol Mn2+, which corresponds to 34.5 mg/
Manganese (II) acetate, was determined. Taking into account that
Manganese (II) acetate as an inorganis salt has no potential for
bioaccumulation and no effects were observed at the hypothetic
concentration of 5.1 mg/L Mn(acO)2 after 10 days in this experiment,
Manganese (II) acetate does not need to be classified according to
In general, algae serve as model
organisms in order simulate actual environmental conditions and how a
testing substance could affect them. Testing only on algae can only give
a limited insight in real conditions, and every testing on additional
species, such as aquatic plants or higher tier mesocosm studies, could
enlarge the insight, how a substance would affect the environment. So
every testing on other aquatic plants and organisms would decrease the
possible uncertainties due to extrapolation from only one species and
hence, can serve to support the results from algae toxicity testing and
to lower any assessment factor.
So, three additional studies were
chosen to support the results from the testing on algae and the
conclusion that no classification of Manganese (II) acetate is required.
A study on Duckweed (Lemna minor)
(Wang S, 1986) revealed a growth inhibition of 50% after 4 days at a
concentration of 96 mg/L, corrected for Manganese (II) acetate and based
on the increase of their front number. Since even the CLP regulation
1272/2008/EC mentions the possibility to base the decision, whether to
classify or not, on the results derived from studies on aquatic plant,
these results may perfectly serve to support the low aquatic toxicity of
Manganese (II) acetate.
Two studies on aquatic protozoae, i.e.
Tetrahymena pyriformis (Bogaerts P, 1998) with an IC50 (9h) of 650.6
mg/L, corrected for Manganese (II) acetate and based on growth
inhibition, and Spirostomum ambiguum (Nalecz-Jawecki G, 1998) with an
LC50 (48h) of 452.4 mg/L, corrected for Manganese (II) acetate and based
on growth mortality, are additionally available.
Although no standard species, the test
organisms Tetrahymena pyriformis and Spirostomum ambiguum broaden
additionally the spectrum of aquatic organisms and, as additional
models, allow a deeper insight in the expectable effects of the test
substance on the aquatic environment. . Therefore, these results should
be also taken into account when assessing the possible hazard of
Manganese (II) acetate to the aquatic environment and consequently the
need for classification.
Although the test durations and
endpoints of these mentioned studies are not equal enough to allow one
to plot them as a species sensitivity distribution, it can be clearly
stated that the available endpoint for algae toxicity on Plectonema
boryanum, i.e. an EC50 value of approx. 34.5 mg/L Manganese (II) acetate
after 10 days, can considered to be the most sensitive endpoint in the
most sensitive species, and should therefore be taken into account when
assessing the possible hazard of Manganese (II) acetate to the aquatic
environment based on the broad base of aquatic food chains.
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