Manganese di(acetate)

Short-term toxicity to aquatic invertebrates

Description of key information

The effects of Manganese (II) acetate on aquatic invertebrates was assessed in a weight-of-evidence approach in various species on several read-across substances:
Espiritu EQ 1995: Acetic acid, Artemia nauplii, EC50 (24h) = 134 µl/L, EC50 (48h) = 132 µl/L
Janssen CR 1993: Acetic acid, Daphnia magna, EC50 (24h) = 71 ± 3 µl/L, EC50 (48h) = 65 ± 9 µl/L
Schweiger G 1956: Mn2+, corrected values for Manganese (II) acetate, 7 days
Carinogammarus Roeselii, LC0 = 45 mg/L, LC100 = 210 mg/L
Tubifex tubifex, LC0 = 600 mg/L, LC100 = 2100 mg/L
Chironomus thummy larvae, LC0 = 750 mg/L, LC100 = 3000 mg/L
Anabolia nervosa larvae, LC0 = 3000 mg/L, LC 100 = 6000 mg/L
Bringmann G 1959: MnCl2, Daphnia magna, LC50 (48h) ≤ 50 mg/L
Khangarot BS 1991: MnSO4 (values referring to element Mn), Tubifex tubifex, EC50 (24h) = 301.3 mg/L, EC50 (48h) = 208.6 mg/L, EC50 (96h) = 170.61 mg/L
Rathore RS 2002: MnSO4 (values referring to element Mn), Tubifex tubifex, EC50 (24h) = 422.36 mg/L, EC50 (48h) = 350.16 mg/L, EC50 (72h) = 275.7 mg/L, EC50 (96h) = 275.7 mg/L
Bengtsson B-E 1978: MnCl2, corrected value for Manganese (II) acetate, Nitocra spinipes, LC50 (96h) = 220.5 mg/L
The most relevant value for further risk assessment was determined to be LC0 (7 d) of 45 mg/L in Carinogammarus Roeselii.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

45 mg/L

Marine water invertebrates

Marine water invertebrates

Effect concentration:

132 mg/L

Additional information

Manganese (II) acetate consists of two ions, namely the Manganese (II) cation and acetate anion. The existing data suggest to follow the approach of assessing the two ions individually and perform the subsequent risk assessment, i.e. deriving PNECs, based on the more distressing ion.

Regarding the acetate anion, an EC50 value of 132 µl/L (approx. 132 mg/L) after 48 h was found in Artemia nauplii (Espiritu EQ, Environmental Toxicology and Water Quality: An International Journal, Vol. 10 (1995) 25-34 0 1995 by John Wiley & Sons, Inc.), and an EC50 (48 h) of 65 ± 9 µl/L, corresponding to approx. 65 mg/L, was found in Daphnids. Taking into account the sensitivity of daphnids towards acidic conditions and the fact, that the pH was not adjusted in both experiments, the EC50 value would be much higher if pH was adjusted, preferably above 100 mg/L as already shown in Artemia nauplii. Additionally, it can be concluded from the magnitude of the observed EC50s, the NOEC in a chronic study will be above 1 mg/L. Acetic acid is part of many metabolic pathways, has an ionic structure and low molecular weight, so it can be concluded, that it has a low BCF and no toxic metabolites will be formed. In Summary, the observed EC50 values obtained from acetic acid and subsequent conclusions do not trigger classification. Consequently, Acetic acid can considered to be non-harmful for aquatic life, especially as it can be assumed that the toxic effects result mainly from the changes in the test water pH which was not adjusted in these experiments. So it can be furthermore concluded that the acetate anion contained in manganese (II) acetate poses no harm to aquatic life and it will be sufficient that all further risk assessment is based on the manganese cation only.

When assessing the toxicity of the manganese (II) cation, most studies on the read across substances exhibited EC50, LC50, LC0 and LC100 values above 100 mg/L on several timepoints up to 7 d:

- Mn2+, corrected values for Manganese (II) acetate, 7 days: Carinogammarus Roeselii, LC0 = 45 mg/L, LC100 = 210 mg/L; Tubifex tubifex, LC0 = 600 mg/L, LC100 = 2100 mg/L; Chironomus thummy larvae, LC0 = 750 mg/L, LC100 = 3000 mg/L; Anabolia nervosa larvae, LC0 = 3000 mg/L, LC 100 = 6000 mg/L (Schweiger G, “Die toxikologische Einwirkung von Schwermetallsalzen auf Fische und Fischnährtiere”,Inaugural-Dissertation zur Erlangung der Doktorwürde der Hohen Naturwissenschaftlichen Fakultät der Ludwig-Maximilians-Universität zu München, Februar 1956)

- MnCl2, Daphnia magna, LC50 (48h)≤50 mg/L (Bringmann G, Gesundheits-Ingenieur, Heft 4 (80. Jahrgang 1959), pg.115ff)

- MnSO4 (values referring to element Mn), Tubifex tubifex, EC50 (24h) = 301.3 mg/L, EC50 (48h) = 208.6 mg/L, EC50 (96h) = 170.61 mg/L (Khangarot BS, Bull. Environ. Contam. Toxicol. (1991) 46:906-912, Springer-Vedag New York Inc.)

- MnSO4 (values referring to element Mn), Tubifex tubifex, EC50 (24h) = 422.36 mg/L, EC50 (48h) = 350.16 mg/L, EC50 (72h) = 275.7 mg/L, EC50 (96h) = 275.7 mg/L (Rathore RS, Ecotoxicologyand Environmental Safety 53, 27}36 (2002) Environmental Research, Section B doi:10.1006/eesa.2001.2100)

- MnCl2, corrected value for Manganese (II) acetate, Nitocra spinipes, LC50 (96h) = 220.5 mg/L (Bengtsson BE, Marine Pollution Bulletin, Vol. 9. pp. 238-241, Pergamon Press Ltd. 1978.)

These high EC50, LC50, LC0 and LC100 values determined in aquatic invertebrate studies covering this endpoint do not reasonable indicate the necessity to perform long-term toxicity test because the NOEC which would be determined in these test is expected to be very high, too, i.e. much higher than the boundary value of 1 mg/L, which is especially supported by the LC0 values determined by Schweiger, 1956, after 7 days. Additionally, the manganese (II) cation as an inorganic ion is neither expected to have a BCF≥500 nor a logKow≥4. Taking into account the classification criteria as set out in regulation 1272/2008/EC, Mn2+ does not trigger classification, and consequently, Manganese (II) acetate does not need to be classified as well as no further long-term testing is indicated.

As the key value (freshwater invertabrates) for further risk assessment the LC0 (7d) of 45 mg/L in Carinogammarus Roeselii was chosen. Since the determined EC50, LC50, LC0 and LC100 values do not indicate further long-term testing, the possibly best surrogate for a chronic NOAEL should be chosen. 7 days is the longest test duration available and the value LC0 indicates that no animal was affected, which corresponds very well to a No Observed Adverse Effects Level. Furthermore, Carinogammarus Roeselii was determined to be the most sensitive species. Consequently, when performing the further assessment of Manganese (II) acetate toxicity and deriving PNECS, it must be taken into account that 45 mg/L is not the usually used EC50 (48 h) value but the LC0 (7 d) value and subsequently lower assessment factors should be applied.

The EC50 for marine water invertebrates of 132 mg/L was chosen on the basis of the effects of Acetic acid on Artemia nauplii, although it is most likely to be caused by changes in the pH, because it is the only value available for marine water invertebrates.