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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Administrative data

Hazard for aquatic organisms


Hazard assessment conclusion:
PNEC aqua (freshwater)
PNEC value:
0.2 µg/L
Assessment factor:
Extrapolation method:
assessment factor
PNEC freshwater (intermittent releases):
2 µg/L

Marine water

Hazard assessment conclusion:
PNEC aqua (marine water)
PNEC value:
0.02 µg/L
Assessment factor:
1 000
Extrapolation method:
assessment factor


Hazard assessment conclusion:
PNEC value:
0.1 mg/L
Assessment factor:
Extrapolation method:
assessment factor

Sediment (freshwater)

Hazard assessment conclusion:
no exposure of sediment expected

Sediment (marine water)

Hazard assessment conclusion:
no exposure of sediment expected

Hazard for air


Hazard assessment conclusion:
no hazard identified

Hazard for terrestrial organisms


Hazard assessment conclusion:
PNEC soil
PNEC value:
0.08 µg/kg soil dw
Extrapolation method:
equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:
no potential for bioaccumulation

Additional information

PNEC aqua- freshwater

As indicated in REACH Guidance R10, "In establishing the size of these assessment factors, a number of uncertainties have been addressed to extrapolate from single-species laboratory data to a multi-species ecosystem. These areas comprise: intra- and inter-laboratory variation of toxicity data; intra- and inter-species variations (biological variance); short-term to long-term toxicity extrapolation; laboratory data to field impact extrapolation.

Application to MMH:

Summary of ecotoxicity results with MMH

Trophic level Species Size/Length in the test Test lab Klimisch rating RSS/study N° EC50 or LC50 result
Type Nominal (mg/L) Measured (mg/L)
Algae Pseudokirchneriella subcapitata  Single cell CIT 1 (specific analytical method) 36966 EAA 72h-ErC50 0.73 <0.019*
Invertebrate Daphnia magna ~5 mm 36967 EAD 48h-EC50 0.26 0.04*
Hyalella azteca (amphipod) ~5 mm Wright-Patterson Air Force Base 4 (unspecific analytical method) AMRL-TR-79-93 48h-LC50 1.2 NR
Asillidae (isopod) NR AMRL-TR-79-93 48h-LC50 0.82 NR
Fish Ictalurus punctatus (catfish) ~8 cm AMRL-TR-79-93 96h-LC50 2.27 1.1 to 2.1
Notemigonus crysoleucas (shiner) ~6 cm AMRL-TR-79-93 96h-LC50 3.54 NR
Lebistes reticulatus = Poecilia reticulata (guppy) ~3 cm 4 (no analytical follow-up) None (Slonim publication) 96h-LC50 2.58 NP

*: extrapolated by taking into account the same "measured/nominal" ratio as at the top-dose of the test (algae: below LOD at the top-dose, daphnia: taken as geometrical mean of LOD and LOQ at the top-dose).

NR: not reported; NP: not performed

Additionally (Klimisch 4, non-standard result): the nominal EC50 for teratogenoicity in amphibian embryos (Xenopus laevis) was between 5 and 7.5 mg/L, with an extremely steep dose-effect curve.

- intra-lab variability was low in the fish studies by Fisher (WP AFB test), in which two independent assays led to very coherent results (in both tested fish species);

- inter-lab variability can not be assessed because tests in different labs were on different species;

- inter-species variability at the trophic level "fish", is very low since very consistent 96h-LC50 results were obtained for three fish species (nominal of 2.58 mg/L in guppy, of 3.54 mg/L for channel catfish, and measured value between 1.1 and 2.1 mg/L for golden shiner corresponding to nominal of 2.27 mg/L);

- inter-trophic variability was low between algae and daphnids, both highly sensitive to MMH, and again low between larger animals like chitine-protected invertebrates, fish or amphibians; this suggests that the most primitive/smallest species, are the most sensitive to MMH;

- intra-species variability can not be assessed since each test is done on a homogeneous group of individuals from the same source; however it is necessarily lower than the inter-species variability (above);

- short-term to long-term extrapolation is not applicable: for the most sensitive trophic level, algae, the test lasting 72h has the status of a long-term assay;

- lab-to-field extrapolations stays the only significant source of uncertainty, and data on degradation suggest possibility of oxidation of MMH in aerated water in presence of catalysts like Cu2+.

Based on these considerations, the data showing high sensitivity of algae to MMH are considered to be already at the extreme end of the sensitivity band for long-term effects of MMH, and a safety factor of 100 is considered sufficient for derivation of PNEC freshwater.

PNECfreshwater = <0.019 mg/L / 100: < 0.2 µg/L

PNEC aqua- marine water

For the reasons indicated above, the standard AF of 10000 is reduced to 1000 for the derivation from acute EC50/LC50 values from three trophic levels.

PNECmarine water = <0.019 mg/L / 1000: < 0.02 µg/L

PNEC intermittent

For the reasons indicated above, the standard AF of 100 is reduced to 10 for the derivation from acute EC50/LC50 values from three trophic levels.

PNECmarine water = <0.019 mg/L / 10: < 2 µg/L

PNEC soil

According to ECHA Guidance R7c, as only aquatic toxicity data, degradation and adsorption data or estimates are available, the substance should be assigned to a “soil hazard category” for a screening assessment:

- adsorption is negligible due to high water solubility and negative log Kow

- the substance is not expected to have a soil half-life> 180 days (EPIsuite estimate: 30 days)

- but the substance is very toxic to aquatic organisms (see water toxicity data)

Therefore the substance falls in Hazard category 2 according to ECHA Guidance Table R.7.11-2.

In this case, equilibrium partitioning is applied as follows for PNECsoil derivation (Equations R.16-5, R.16-6, R.16-7, R.16-74 and R.10-5); a confirmatory short-term soil toxicity testing with the most sensitive organism group should be proposed, but only at 100 t/year according to REACH Annexes VII-VIII, i.e. this proposal is not required for the intended registration band:

Kair-water = "dimensionless Henry's law constant" = Henry's law constant / (R x Temp) = 3.071E-1 (highest estimate from EPIsuite) / (8.314 x 285) = 1.30E-4

Kpsoil (L/kg) = Focsoil x Koc = 0.02 kg o.c./kg solid x 13.31 L/kg (highest estimate from EPIsuite) = 0.2662

Ksoil-water = Fair(soil) x Kair-water + Fwater(soil) + (Fsolid(soil) x Kpsoil x RHOsolid / 1000)

= 0.2 m3 air/m3 soil x 1.30E-4 + 0.2 m3 water/m3 soil + (0.6 m3 solid/m3 soil x 0.2662 L/kg x 2500 kg/m3 / 1000) = 0.60

PNECsoil (w.w.)= 1000 x PNECwater x Ksoil-water /RHOsoil = < 0.2 mg/m3 x 0.60 / 1150 kg/m3 = <0.1 µg/kg soil w.w.

Unit conversion per soil dry weight:

PNECsoil (d.w.)= PNECsoil(w.w.) x CONVsoil = 1000 x PNECwater x Ksoil-water/RHOsoil x [RHOsoil / (Fsolid x RHOsolid)] = < 0.2 mg/m3 x 0.60 / (0.6 m3 solid/m3 soil x 2500 kg/m3) = <0.08 µg/kg soil d.w.

Conclusion on classification

Based on:

- high acute aquatic toxicity (lowest EC50 or LC50: algae: < 0.019 mg/L),

- absence of readily degradability (a degradation was shown, which depends on dissolved oxygen/Cu2+ and pH but it can not be taken into account for classification),

The substance should be classified as:

-Aquatic Acute Category 1 according to GHS/CLP.

- Aquatic Chronic Category 1 according to GHS/CLP.

And the Multiplying factor "M" according to GHS/CLP Table 4.1.3, is "at least 10" as the exact value of the critical EC50/LC50 (algae) is unknown. Due to this incertitude, it is not recommended to use this M factor to assess environmental risks related to MMH-containing formulations.