Tangled Multi-Walled Carbon Nanotubes

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to OECD Guideline, GLP compliant

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

Each concentration of GRAPHISTRENGTH C100 was prepared as WAF for concentrations varying from 5 mg/L to 100 mg/L (geometric factor close to 2.1) in 2 litres of dilution water.
GRAPHISTRENGTH C100 was maintained in suspension by stirring during distribution in the test flasks. However, after filling and between each renewal, there was a sedimentation of the test item to the bottom of flasks.
Results of the acute toxicity test were used to define the concentration range used in the reproduction test (an EC50 value > 100 mg/L was found on Daphnia magna acute toxicity test)
These preparation was performed for each medium renewal every 2 or 3 days.

Test organisms (species):

Daphnia magna

Details on test organisms:

Biological reagent: organisms Daphnia magna Straus (Cladocera, Crustacea), clone 5 or clone A. Animals come from a stock breading in the laboratory reared in VOLVIC® water added with vitamin B12, Na2SeO3, 5H2O, spiruline, Calcium, Magnesium unicellular green fresh-water algae Pseudokirchneriella subcapitata and Chlorella vulgaris. Selection of test organisms less than 24 hours old is made by filtration.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Test temperature:

19.4 ± 2.6 °C Variation in temperature was higher than expected, due to a temperature control issue in the laboratory

pH:

Fresh solutions: 7.8 - 8.1

Dissolved oxygen:

Fresh solutions: 8.9 - 9.3

Nominal and measured concentrations:

Nominal concentrations: 0 - 5 - 10 - 22 - 47 - 100 mg/L

Details on test conditions:

Dilution water was prepared with Volvic® water complemented as follow:

0.1 ml/L of B12 vitamin solution (1 µg/L)
0.1 ml/L of Na2SeO3.5H2O solution (6.7 µg/L)
1ml/L of calcium / magnesium solution: Ca(NO3)2.4H2O : 208 g/L and MgCl2.6H2O : 28 g/L.
These solutions were prepared with ultra-pure water (resistivity > 18Mohm), reagents « analytical grade ».

Reference substance (positive control):

yes

Remarks:

K2Cr2O7

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

47 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

GRAPHISTRENGTH C100 Nominal Concentrations (mg/L)	0.00	5.00	10.00	22.00	47.00	100.00
Vessel 1	222	192	213	171	169	26
Vessel 2	193	222	192	190	109	170
Vessel 3	208	180	190	192	169	191
Vessel 4	202	207	201	183	181	158
Vessel 5	218	0	183	189	157	166
Vessel 6	158	174	198	194	170	173
Vessel 7	165	197	185	214	211	156
Vessel 8	183	203	192	156	158	161
Vessel 9	208	186	0	179	176	185
Vessel 10	180	218	184	196	197	143
Ne Total	1937	1779	1738	1864	1697	1529
Replicates number	10	9	9	10	10	10
Mean	193.70	197.67	193.11	186.40	169.70	152.90
Standard deviation	21.78	64.40	61.74	15.60	27.08	46.73
Coefficient of variation (%)	11.25	36.20	35.52	8.37	15.96	30.56
% Inhibition	-	-2.05	0.30	3.77	12.39	21.06

Validity criteria fulfilled:

yes

Conclusions:

Exposure of daphnias to Graphistrength C100 multiwall carbon nanotubes (without added vehicle) resulted in an inhibition of reproductionat 100 mg/L (LOEC). NOEC = 47 mg/L in the conditions of the test.

Executive summary:

The chronic toxicity (inhibition of reproduction) of the test itemGRAPHISTRENGTH C100toDaphnia magnawas assessed according to the guideline 211 of the OECD.

Daphniawere exposed to a range of concentrations ofGRAPHISTRENGTH C100dispersed in dilution water. The chronic effect measured during the assay was the inhibition of reproduction after time periods of 21 days.

EC₅₀, LOEC and NOEC values are summarised in the following table:

 

 

Measured concentrations	EC50Value	LOEC	NOEC
mg/L	317.75	100	47

Description of key information

Inhibition of reproduction of Daphnia magna has been investigated through an OECD 211 study. A NOEC of 47 mg/L (nominal) has been observed.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

47 mg/L

Additional information

An OECD 211 study (inhibition of reproduction of Daphnia magna) gives a NOEC of 47 mg/L (nominal).