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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Endpoint:
bioaccumulation in aquatic species, other
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Reason / purpose:
reference to other study
Qualifier:
no guideline followed
Principles of method if other than guideline:
Rainbow trout and zebra mussel were exposed to a single concentration of NMMO during 3 months. Sampling and analysis of concentrations in whole organisms and tissues was performed at the end of the exposure period.
GLP compliance:
no
Radiolabelling:
no
Details on sampling:
Samples of the animals and tissues (only for fish: liver, kidney, muscle) were taken once, at the end of the 3 month exposure period.
Vehicle:
no
Details on preparation of test solutions, spiked fish food or sediment:
Stock solutions were newly prepared each third day.
Test organisms (species):
other: Oncorhynchus mykiss and Dreissena polymorpha
Details on test organisms:
Oncorhynchus mykiss = rainbow trout (fish)
- Age: 1-year-old
- Weight: average 18 g (initially)
- Source: der Fischzucht Achleitner in Mattighofen
- Feeding during the test: daily, with Tagger C19/888

Dreissena polymorpha = zebra mussel (invertebrate)
- Source: Traunsee, sampled from a depth of 2-3 m
- Feeding during the test: daily, with fresh yeast or finely homogenized Tetramin
Route of exposure:
aqueous
Test type:
not specified
Water / sediment media type:
natural water: freshwater
Total exposure / uptake duration:
92 d
Hardness:
110 mg CaCO3/L
Test temperature:
12.0°C (October), 10.2°C (November), 7.5°C (December)
pH:
8.2
Dissolved oxygen:
high, continuous aeration
TOC:
no data
Salinity:
not applicable
Details on test conditions:
TEST SYSTEM
- Test vessel: 24-L aquaria
- Aeration: continuous
- Continuous flow-through system, peristaltic, 465-572 mL/min for fish, 288-369 mL/min for mussels
- No. of organisms per vessel: for fish: 30 (initially, only 11 were sampled at day 92, not clear how many were used for whole organism / tissue analysis) / for mussels: not reported
- No. of vessels per concentration (replicates): 2
- No. of vessels per control / vehicle control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: activated carbon-filtered tap water
- Frequent measurement of test substance concentrations (12x in 3 months) and ammonia concentrations (6-9x in 3 months)

OTHER TEST CONDITIONS
- Photoperiod: 12L:12D
Nominal and measured concentrations:
Single exposure concentration (nominal): 10 mg/L NMMO
Measured concentration: 7.1-12.0 mg/L
Details on estimation of bioconcentration:
Concentration in tissue / concentration in water = BCF
Type:
BCF
Value:
< 10 L/kg
Basis:
whole body w.w.
Calculation basis:
steady state
Remarks on result:
other: for both rainbow trout and zebra mussel
Remarks:
Conc.in environment / dose:10 mg/L
Details on results:
None of the chromatograms showed the presence of NMMO in whole organisms/tissues. The NMMO concentration is therefore < 100 mg/kg
Validity criteria fulfilled:
not specified
Conclusions:
The BCF is < 10 L/kg, which confirms that the substance has no specific capacity for bioaccumulation in aquatic organisms.
Executive summary:

In this study, rainbow trout (Oncorhynchus mykiss, 1-yr-old) and zebra mussel (Dreissena polymorpha) were exposed to 10 mg/L NMMO during 92 days. The exposure concentration was monitored and remained stable. After 3 months, no NMMO could be detected in whole organisms or tissues, implying that the BCF is < 10 L/kg, which confirms that the substance has no specific capacity for bioaccumulation in aquatic organisms. It must be kept in mind that the single exposure concentration of 10 mg/L is rather low compared to concentrations known to cause toxicity (e.g., acute LC50 of 31200 mg/L in rainbow trout).

Endpoint:
bioaccumulation in aquatic species: fish
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
the study does not need to be conducted because the substance has a low potential for bioaccumulation based on log Kow <=3

Description of key information

According to REACH Annex IX 9.3 column 2, testing of bioaccumulation is not required if there is no indication for bioaccumulation based on other properties of the substance (for instance log Kow <= 3). The log Kow of NMMO is -1.20, therefore, bioaccumulation testing is not required. Nevertheless, a study was conducted (Lackner, 1991), providing supporting evidence, that NMMO has no bioaccumulating properties (BCF <10 L/kg).. 

Key value for chemical safety assessment

Additional information

A single study (Lackner, 1991) investigating bioaccumulation of NMMO in fish (rainbow trout, Oncorhynchus mykiss) and zebra mussel (Dreissena polymorpha) indicated that the substance has no potential for bioaccumulation. After 92 days of exposure to a single concentration (10 mg/L) no NMMO could be traced in whole organisms or tissues. The BCF was therefore < 10 L/kg ww. It should be kept in mind that the exposure concentration was quite low compared to concentrations causing toxic effects to aquatic organisms. Nevertheless, the results of this study confirm what was expected based on the low log Kow of the substance.