No IUPAC name is currently defined for Cashew (Anacardium occidentale) Nutshell Extract, Decarboxylated, Distilled (“Distilled Grade”).

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Remarks:

The study was conducted to an internationally recognised method (OECD 301D). There were deviations from this guideline, but these were implemented to address the poor water solubility of the test substance.

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

yes

Remarks:

Modifications to the concentrations of suspended solids and test material have been made to account for the poor water solubility of the test substance

Principles of method if other than guideline:

The OECD guideline specifies a suspended solids concentration of 20 mg/l, whereas the study used a concentration of 30 mg/l. The guideline specifies a test material concentration of 5-10 mg ThOD/l, whereas the study used a concentration of approximately 20 mg ThOD/l. The guideline specifies that at least 10 replicates should be used for each of the test substance, positive control and control blank as well as 6 replicates for a toxicity control, whereas this study used three replicates for the test substance and positive control and an unknown number of control blanks. No details of toxicity controls were reported.

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

Mixed bacterial inoculum (30 mg suspended solids/l), stabilised under laboratory conditions for one week prior to the study.

Duration of test (contact time):

28 d

Initial conc.:

18.6 - 19.8 other: mg ThOD/flask

Based on:

other: ThOD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Defined mineral medium (according to OECD tests) inoculated with mixed bacterial inoculum, stabilised under laboratory conditions for one week
- Test temperature: Not reported
- pH: Not reported
- CEC (meq/100 g): Not reported
- Aeration of dilution water: Not reported
- Suspended solids concentration: 30 mg/l


TEST SYSTEM
- Number of culture flasks/concentration: Three
- Method used to create aerobic conditions: Test vessels were shaken continuously to assure steady state oxygen partitioning between liquid and gass phase
- Test performed in open system: No, test vessels were closed glass bottles
- Volume of test vessels: Approximately 300 ml, two thirds test mixture, one third air


SAMPLING
- Sampling frequency: Sampling conducted on days 7, 14, 21 and 28
- Sampling method: Total oxygen uptake was calculated from the measured dissolved oxygen
- Sterility check if applicable: Not reported
- Sample storage before analysis: Not reported

Reference substance:

acetic acid, sodium salt

Remarks:

>99.5% a.i.; Batch number 0137A

Parameter:

% degradation (O2 consumption)

Value:

46

Sampling time:

7 d

Parameter:

% degradation (O2 consumption)

Value:

72

Sampling time:

14 d

Parameter:

% degradation (O2 consumption)

Value:

86

Sampling time:

21 d

Parameter:

% degradation (O2 consumption)

Value:

96

Sampling time:

28 d

Details on results:

Refer to Table 3.

Results with reference substance:

Sodium acetate was 97% degraded after 28 days. Refer to Table 4.

Table 3: Biodegradation of Cardolite NC-511 (a distilled grade CNSL sample)

Measurement	Replicate	Incubation time (days)
		7	14	21	28
Oxygen concentration (mg O2/l)	1	6.35	7.58	8.14	8.29
	2	5.31	7.83	8.20	8.29
	3	7.03	7.01	8.28	8.15
Oxygen saturation value (mg O2/l)	-	9.20	9.20	9.20	9.20
Relative oxygen uptake	1	0.29	0.15	0.10	0.06
	2	0.40	0.13	0.09	0.06
	3	0.22	0.22	0.08	0.08
Total oxygen uptake	1	0.29	0.44	0.54	0.60
	2	0.40	0.53	0.62	0.68
	3	0.22	0.43	0.51	0.59
Total oxygen uptake x oxygen capacity of flasks	1	8.49	12.98	15.87	17.62
	2	11.80	15.50	18.19	19.95
	3	6.32	12.63	15.07	17.27
% oxidation	1	46	70	85	95
	2	60	78	92	101
	3	34	67	80	92
	Average	46	72	86	96

Table 4: Biodegradation of sodium acetate

Measurement	Replicate	Incubation time (days)
		7	14	21	28
Oxygen concentration (mg O2/l)	1	4.27	8.34	8.79	8.57
	2	4.26	8.35	8.65	8.52
	3	4.47	8.34	8.67	8.39
Oxygen saturation value (mg O2/l)	-	9.20	9.20	9.20	9.20
Relative oxygen uptake	1	0.52	0.07	0.03	0.03
	2	0.52	0.07	0.04	0.03
	3	0.49	0.07	0.04	0.05
Total oxygen uptake	1	0.52	0.59	0.61	0.64
	2	0.52	0.59	0.63	0.66
	3	0.49	0.56	0.60	0.65
Total oxygen uptake x oxygen capacity of flasks	1	15.04	17.10	17.90	18.78
	2	15.07	17.10	18.35	19.36
	3	14.40	16.48	17.65	19.08
% oxidation	1	76	87	91	95
	2	76	87	93	96
	3	73	83	89	97
	Average	75	86	91	97

Interpretation of results:

readily biodegradable

Conclusions:

Based on these results, Cardolite NC-511 (a distilled grade CNSL sample) can be regarded as very highly biodegradable.

Executive summary:

A 28 day aerobic ready biodegradability study (to OECD Guideline No. 301D – Closed Bottle Test) was carried out using Cardolite NC-511(a distilled grade CNSL sample). The effects of the test substance on ready biodegradability were assessed based on the measurement of chemical oxygen demand (COD) using an activated sludge inoculum (from a domestic wastewater plant). Test performance was evaluated using the reference substances sodium acetate.

 

This toxicity study is classified as not reliable (Klimisch Code 2) on the basis that there were some deviations from the test guideline.

 

Results Synopsis

 

There was 96% degradation of the test substance (Cashew Nutshell Extract, Decarboxylated, Distilled (Distilled Grade))after 28 days.

There was 97% degradation of the reference substance after 28 days meaning the test was considered valid.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

A 28 day aerobic ready biodegradability study (to OECD Guideline No. 301D – Closed Bottle Test) was carried out using Cardolite NC-511 (a Distilled Grade sample). The effects of the test substance on ready biodegradability were assessed based on the measurement of chemical oxygen demand (COD) using an activated sludge inoculum (from a domestic wastewater plant). Test performance was evaluated using the reference substances sodium acetate.

This toxicity study is classified as not reliable (Klimisch Code 2) on the basis that there were some deviations from the test guideline.

Cardolite NC-511 (a Distilled Grade sample) was classified as readily biodegradable as there was 96% degradation of the test substance after 28 days.