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EC number: 205-633-8
CAS number: 144-55-8
Both sodium and bicarbonate are naturally present in aquatic ecosystems.
The bicarbonate concentration are reported for a total number of 77
rivers and the sodium concentration for a total number of 75 rivers in
North-America, South-America, Asia, Africa, and Oceania. For sodium the
10th- and 90th-percentile were 1.5 and 68 mg/l, respectively, for
bicarbonate the 10th- and 90th-percentile were 20 and 195 mg/l,
respectively (OECD SIDS on sodium bicarbonate (2002), pg. 19 -23).
Because the natural pH, bicarbonate and sodium concentration (and also
their fluctuations in time) varies significantly between aquatic
ecosystems, it is not considered useful to derive a generic PNEC or
PNECadded. To assess the potential environmental effect of a sodium
bicarbonate discharge, the increase in sodium, bicarbonate and pH should
be compared with the natural values and their fluctuations and based on
this comparison it should be assessed if the anthropogenic addition is
acceptable. The use of sodium bicarbonate could potentially result in an
aquatic emission of sodium bicarbonate and it could locally increase the
sodium and bicarbonate concentration in the aquatic environment. In
contrast to sodium carbonate, sodium bicarbonate does not increase the
pH of water to high and/or lethal levels (OECD SIDS on sodium
bicarbonate (2002), pg. 19 -23). An addition of bicarbonate to water
will converge the pH to a value of 8.34. The value of 8.34 is equal to
(pKa1+ pKa2)/2. In other words, if the initial pH of the receiving water
is for example 7.0 then an addition of bicarbonate will increase the pH
but it will never be higher than 8.34. However, if the initial pH of the
receiving water is for example 9.0 then an addition of bicarbonate will
decrease the pH but it will never be lower than 8.34 (OECD SIDS on
sodium bicarbonate (2002), pg. 19 -23).
Key aquatic toxicity studies are available and here summarised:
· In a 96-hr acute flow-through test with bluegill sunfish (Lepomis
macrochirus) a NOEC of 5,200 mg/l and a LC50 of 7,100 mg/l were
determined (Machado, 1993).
· A reliable publication (K2) is present exposing newly fertilised
eggs of fathead minnow (Pimephales promelas) for 60 days to
NaHCO3 at concentration range of 300-1,400mg/L. Results showed overall
an LC50 at 37 days of 675 mg/L NaHCO3 and a NOEC of 400 mg/L NaHCO3
based on mortality (Farag et al, 2013).
· In a 48-hr acute flow-through test with Daphnia
magna a NOEC of 3,100 mg/L and a LC50of 4,100 mg/l were determined
· A weight of evidence approach was used for the long-term toxicity
to invertebrates. A reproduction test with D. magna demonstrated
that the 21-day Daphnia magna NOEC is higher than 576 mg/L (Leblanc and
Surprenant, 1984). In addition, Farag et al. (2013) conducted a study
exposing neonates of the water flea, C. dubia, for 7 days to a
concentration range of 500-1500 mg/L of NaHCO3. Results showed a LC50 of
1192 mg NaHCO3/L and IC20 for reproduction of 359 mg NaHCO3/L.
Furthermore, newly transformed freshwater mussels, L. siliquoidea,
were also exposed in a separated experiment for 10 days to a
concentration range of 500-2000 mg/L of NaHCO3. Results showed a EC50
and an IC20 for immobilization of 1061 mg NaHCO3/L and 952 mg NaHCO3/L,
· In accordance with section 1 of Annex XI of the REACH Regulation,
Algae toxicity tests don’t need to be conducted as in the aquatic
environment sodium bicarbonate is dissociated into sodium and
bicarbonate ions. Furthermore, bicarbonate ions are provided in high
concentrations in algae growth medium, in order to ensure a sufficient
carbon source for the organisms. Sodium ions are also present in high
concentrations in the growth medium as essential ions. Indeed, two
reliable studies (K 2) testing the increase of growth of algae with the
addition of NaHCO3 are available. Nunez et al. (2016) exposed two marine
diatoms, Phaeodactylum tricornutum and Nannochloropsis salina,
to a concentration range of 0.5 to 5 g/L of NaHCO3 for 1-12 days during
their growth phase, to assess their optimal growth condition. Indeed,
with increasing test item concentration algae’s growth rate increased.
Thus, a NOEC of 5000 mg/ L for inhibition effect was determined.
Differently, Zhou et al. (2016) exposed three marine red macroalgae, Gracilaria
lemaneiformis, Gracilaria vermiculophylla and Gracilaria chouae,
to a concentration range of 84 to 420 mg/L of NaHCO3 for 14 days to
assess their optimal growth condition. Indeed, with increasing test item
concentration algae’s growth rate increased up to the concentration of
420 mg/L (LOEC), when all the algae exhibited a significant grow rate
inhibition compared with the control (NOEC 336 mg/l). Chl a, at the end
of the experiment was also determined. A LOEC of 420 mg/L was determined
for chlorophyll inhibition for G. lemaneiformis, G. vermiculophylla. G.
chouae at the highest concentration tested showed a decrease but not
significant decrease of Chl a compared with the control, thus a NOEC >
420 mg/L was determined.
Therefore, sodium bicarbonate has not to be classified for aquatic
toxicity in accordance with CLP Regulation (EC) No 1272/2008.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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