Bulnesia sarmienti, ext., acetate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Results derived form a valid read-across, with adequate and reliable documentation / justification.

Justification for type of information:

The read across justification is presented in the Endpoint Summary. The corresponding documentation file is also attached there.

Reason / purpose for cross-reference:

read-across source

Key result

Parameter:

% degradation (inorg. C analysis)

Value:

80

Sampling time:

28 d

Remarks on result:

other: Based on read-across information

Validity criteria fulfilled:

yes

Remarks:

information is supported with read across justification

Interpretation of results:

readily biodegradable

Remarks:

> 70% biodegradation is predicted

Conclusions:

Biodegradation value derived for Guaiyl Acet is 80% at day 28, which is above the 70% cut off value at which full biodegradation in the environment is anticipated.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

29 December 2008 to 04 February 2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Information used for read-across to Guaiyl Acet, multi-constituent.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)

Version / remarks:

2006

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Secondary activated sludge was obtained from the WWTP Nieuwgraaf in Duiven, The Netherlands (29-12-2008). The WWTP Nieuwgraaf is an activated sludge plant treating predominantly domestic waste water. The activated sludge was preconditioned to reduce the endogenous respiration rates. To this end, 400 mg Dry Weight (DW)/L of activated sludge was aerated for one week with moist air. The sludge was diluted to a concentration of 4 mg DW/L in the test vessels.

Duration of test (contact time):

28 d

Initial conc.:

31.9 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

inorg. C analysis

Remarks:

(as % of Theoretical inorganic carbon)

Details on study design:

Test bottles:
The test was performed in 120 mL serum flasks with butyl septa and crimp-on aluminum seals (control and reference) or Mininert valves (test substance) seals. The volume of the liquid phase was 80 mL.

Nutrient solution and stock solutions:
The nutrient medium of the Carbon Dioxide Headspace Test contained per liter of deionized water; 85 mg KH2PO4, 217.5 mg K2HPO4, 334 mg Na2HPO4·2H2O, 5 mg NH4CL, 22.5 mg MgSO4·7H2O, 27.5 mg CaCl2, 0.25 mg FeCl3·6H2O. 1-Octanol was added to the vessels using a stock solution in dichloromethane of 1.0 g/L. The test substance is a poorly soluble substance in water. The test substance was directly added to the vessels.

Test procedure:
Use was made of 30 vessels containing only inoculum, 30 vessels containing test substance and inoculum, and 9 vessels containing 1-octanol and inoculum. One additional bottle of each series was included to allow determination of the pH at day 28. 1-octanol in dichloromethane (2.5 mL) was directly added to bottles. The solvent was subsequently allowed to evaporate in a ventilated hood for 24 hours (Nyholm and Seiero, 1989). Volumes of 3 µL of the test substance were added to the vessels. The amounts of test substance added were checked by weighing 10 times, 3 µL of test substance.
The concentrations of the test substance and 1-octanol in the vessels were 31.9 and 31.3 mg/L, respectively, representing organic carbon concentrations of 24.5 and 23.1 mg/L respectively. The inoculum was diluted to 4 mg DW/L in the test vessels. 80 mL of each of the prepared solutions was dispensed into the respective group of test vessels. The zero time vessels were analyzed for total inorganic carbon using the TOC apparatus upon adding 1 mL of a freshly prepared 7 M NaOH solution with 1 mL plastic syringes. The remaining vessels were incubated in the dark. Triplicate vessels of all series were withdrawn for analyses of the carbon dioxide formed at day 3, 7, 10, 14, 17, 21 and 28.
The biological reactions in the test vessels were stopped by injecting 1 mL of a 7 M NaOH solution through the septum or Mininert valves. Before analysis of the inorganic carbon, the test vessels were shaken for at least one hour. Next, the particles in the vessels were allowed to settle and a suitable sample was withdrawn from the vessel with a syringe for analysis. The conversion of carbon dioxide to carbonate with sodium hydroxide should result in a negligible carbon dioxide concentration in the headspace. This was checked by adding 10 and 20 mg/L of carbonate-carbon to the mineral salts medium in the test vessels (in triplicate). A control without addition of carbonate was included. These test vessels were incubated at 20 oC on a rotary shaker at 180 rpm for 24 hours. Next, sodium hydroxide (1 mL, 7 M) was added and the vessels were shaken for one hour. The inorganic carbon was measured in the alkaline medium using the TOC analyzer.

Test conditions:
The pH of the media was 7.4 at the start of the test. The pH of the medium at day 28 ranged from 7.4 to 7.5. Temperature range recorded during the test was 19 to 21°C.

Reference substance:

other: 1-octanol (99.0% purity)

Test performance:

The mean carbonate-carbon concentrations and standard deviations in vessels containing the nutrient solution, nutrient solution and 10 mg/L carbonate-carbon and nutrient solution and 20 mg/L of inorganic carbon were 2.1 +/- 0.7, 14.0 +/- 0.3 and 24.1 +/- 1.1 mg/L, respectively. The carbon added was therefore recovered for 119% and 110% at 10 and 20 mg/L carbonate-carbon, respectively. This demonstrates that carbon dioxide was removed from the headspace adequately.
The mean amount of inorganic carbon content present in the blank controls at the end of the test is 4.7 mg/L which is above the criteria (< 3 mg C/L), this is not considered to have affected the results. The increase of inorganic carbon content in the blank controls is 3.1 mg/L at day 28 which is <= 15% of the inorganic carbon added initially as test substance.
The viability of the inoculum and validity of the test were supported by the results of the reference substance, 1-octanol from which 89% of the theoretical carbon dioxide was evolved at day 14.

Key result

Parameter:

% degradation (inorg. C analysis)

Value:

80

Sampling time:

28 d

Details on results:

The test substance is biodegraded 80% at day 28 in the carbon dioxide headspace test. The pass level of 60% was not reached within 10 days upon achieving 10% biodegradation. Failing the 10-day window criterion may be caused by 1) the toxicity of the test substance to microorganisms and/or 2) the use of test vessels which were sacrificed and/or 3) the poor water solubility of the test substance. The possible toxicity of terpenes has been reviewed by Sikkema et al (1995). The “linear” biodegradation curve with biodegradation percentages which do not always increasing with time, may be explained with the poor water solubility of the test substance and the set-up of the test (sacrificing of test bottles).
The 10-day time window criterion was developed on the assumption that compounds degrade according to “standard” logarithmic growth curves as found for water soluble compounds. The time-window should therefore be ignored as a pass fail criterion for the test substance. The test substance is therefore classified as readily biodegradable solely based on the biodegradation percentage of 80% found at day 28.

Results with reference substance:

1-Octanol was degraded 89% at 14 days.

Toxicity to inoculum:

Inhibition of the degradation of a well degradable compound e.g. 1-octanol by the test compound in the carbon dioxide headspace test was not determined because possible toxicity of the test substance to microorganisms degrading 1-octanol is not relevant. All triplicate measurements of the inorganic carbon in the test vessels did vary to a big extent. An explanation of this phenomenon might be the toxicity of the test substance to the micoorganisms. Inhibition of the biodegradation due to the "high" initial concentration of the test compound can therefore not be excluded.

Validity criteria fulfilled:

yes

Remarks:

Degradation of reference substance = 89% at day 14 (criteria > 60%).

Interpretation of results:

readily biodegradable

Remarks:

> 70% degradation is seen.

Conclusions:

The substance is considered to be readily biodegradable based on the biodegradation percentage of 80% at day 28. This is > 70% and full biodegradation is anticipated in the environment.

Executive summary:

In order to assess the biodegradation of the substance, a screening test was performed according to OECD TG 310 (Carbon Dioxide Headspace Test) and under GLP conditions. In this study secondary activated sludge (4 mg dry weight/L) was exposed to 31.9 mg/L substance for 28 days. The increase of inorganic carbon content in the blank controls was 3.1 mg/L at day 28 which is <= 15% of the inorganic carbon added initially as test substance. The viability of the inoculum and validity of the test were supported by the results of the reference substance, 1-octanol from which 89% of the theoretical carbon dioxide was evolved at day 14. The test substance was biodegraded 80% at day 28 in the carbon dioxide headspace test. This value is above the 70% cut off value and full biodegradation can be anticipated in the environment, therefore the substance is considered readily biodegradable.

Description of key information

Guaiyl Acet-multi is readily biodegradable based on read across from Guaiyl Acet-mono (tested in an OECDTG 310)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

First the experimental information from the source is presented and thereafter the read across justification.

Guaiyl Acet-mono and its ready biodegradability:

In order to assess the biodegradation of the substance, a screening test was performed according to OECD TG 310 (Carbon Dioxide Headspace Test) and under GLP conditions. In this study secondary activated sludge (4 mg dry weight/L) was exposed to 31.9 mg/L substance for 28 days. The increase of inorganic carbon content in the blank controls was 3.1 mg/L at day 28 which is <= 15% of the inorganic carbon added initially as test substance. The viability of the inoculum and validity of the test were supported by the results of the reference substance, 1-octanol from which 89% of the theoretical carbon dioxide was evolved at day 14. The test substance was biodegraded 80% at day 28 in the carbon dioxide headspace test. This value is above the 70% cut off value and full biodegradation can be anticipated in the environment, therefore the substance is consideredreadily biodegradable.

Guaiyl Acet-multi (Cas no. 94333-88-7) and its ready biodegradability in water using read across information from source substance Guaiyl Acet-mono (Cas no. 134-28-1)

Introduction and hypothesis for the analogue approach

Guaiyl Acet is a multi-constituent containing two main constituents. The substance has a hydrocarbon backbone to which an ester is attached. This backbone contains two fused rings: a cyclopentane and a cycloheptane ring, with a double bond. The ester is an acetate group attached to the larger ring via an isopropyl group. For one of its constituents there are data on biodegradation in water – screenings- system is available. In accordance with Article 13 of REACH,lacking information can be generated by means of applying alternative methods such as QSARs, grouping and read-across. For assessing the biodegradation of Guaiyl Acet in water the analogue approach is selected because for one constituent reliable biodegradation data is available.

Hypothesis: The multi-constituent Guaiyl Acet has a similar biodegradability as one of its main constituents Guaiyl Acet-mono.

Available experimental information: Guaiyl Acet-monowas tested according to OECD guideline 310 in compliance with GLP principles, Reliability 1. The substance was biodegraded 80% at day 28. This value is above the 70% threshold, on which bases full environmental biodegradation can be anticipated. Therefore the substance is considered readily biodegradable.

Target chemical and source chemical(s)

Chemical structures of the two main constituents of Guaiyl Acet are shown in the data matrix, including physico-chemical properties thought relevant for biodegradation.

Purity / Impurities

Guaiyl Acet-multi is a multi-constituent containing two main constituents, which are structural isomers with the difference that the double bond is one position different. The other constituents are all < 10% and have similar structural features.

Analogue approach justification

According to Annex XI 1.5 read across can be used to replace testing when the similarity can be based on a common backbone and a common functional group. When using read across the result derived should be applicable for C&L and/or risk assessment and it should be presented with adequate and reliable documentation.

Analogue justification:In the RIFM database a search on related materials was performed using the generic Cas no. 94333-88-7, which revealed no analogues. When using CAS numbers of the main constituents (Cas no. 882881-27-8 and 134-28-1) this resulted in relevant information on Cas no. 134-28-1. As no other relevant information was found using the OECD QSAR toolbox on structural similarity with Tanimoto 60%, the constituent with Cas no 134-28-1 was used for read across.

Structural similarities and differences:The two main constituents ofGuaiyl Acet-multi have the same hydrocarbon backbone and a functional ester group being acetate. The key difference is the position of the double bond. One constituent has it on the position of the fused ring (the source) the other constituent has it in the heptane ring one position from the fused side. This one position difference is not expected to influence the biodegradability of the substance. 

Similarity in bioavailability: The two constituents of Guaiyl Acet-multi are expected to have a similar bioavailability based on the similarity in chemical structure, the same molecular weight they are both liquids. The predicted and measured physico-chemical properties of Guaiyl Acet-multi are aligned with the predicted ones showing low water solubility and log Kow of ca. 6.

Similarity in biodegradable groups: The two constituents of Guaiyl Acet-multi are expected to have a similar biodegradability potential based on the similarity in structure and functional group. This is supported by BIOWIN which presents the same Fragment profile, BIOWIN 5 (0.4749) and BIOWIN 6 (0.2025) prediction for both substances (presented in the Table below).

Uncertainty of the prediction: In view of the reasoning above there are no remaining uncertainties.

 

Table: The anticipated degradation of Guaiyl Acet-multi and source substance Guaiyl Acet-mono (Cas no. 134-28-1).

Fragment	Guaiyl Acet-multi	Guaiyl Acet-mono Cas no. 134-28-1
	Target	Source
	Number fragments	Number fragments
Ester [-C(=O)-O-C]	1	1
Carbon with 4 single bonds & no hydrogens	1	1
Methyl [-CH3]	5	5
-CH2- [Cyclic]	5	5
-CH- [Cyclic]	3	3
BIOWIN 5	0.4749	0.4749
BIOWIN6	0.2025	0.2025

 

Data matrix

The relevant information on physico-chemical properties and biodegradation characteristics are presented in the data matrix below.

Conclusions on the ready biodegradability

When using read across the result derived should be applicable for C&L and/or risk assessment and be presented with adequate and reliable documentation.

For Guaiyl Acet-mono (Cas no 134-28-1) being one of the main constituents of Guaiyl Acet-multi, a ready biodegradability test is available performed according to OECD TG 310 and GLP principles (Reliability 1). The test substance was biodegraded 80% at day 28, which is above the 70% value on which based ready biodegradability can be assigned. This information can be used for read across to the Guaiyl Acet-multi.

Final conclusion on fate: Guaiyl Acet-multi isreadily biodegradable.This result is applied for C&L and/or risk assessment.

 

Data matrix of Guaiyl Acet-multi using read across from Source substance (Cas no 134-28-1).                                                                                                                                                                                                                                         

	Target substance:	Source substance:
Common names	Guaiyl Acet-multi	Guaiyl Acetate-mono
Cas no	Generic: 94333-88-7 One main constituent: 882881-27-8	134-28-1
Chemical structures
Empirical formula	C17H28O2	C17H28O2
EC numbers	305-067-2	205-135-0
Reach registration	Registered for 2018
Molecular weight	264.4	246.4
Physico-chemical data
Physical state	Liquid	Liquid
Vapour pressure Pa (measured)	0.09
Vapour pressure Pa (EPISUITE)	0.0302	0.0302
Water solubility mg/L (measured)	2.51
Water solubility mg/L (EPISUITE)	0.1779	0.0908
Log Kow (measured)	6.6
Log Kow (EPISUITE)	5.91	6.25
Fate
Biodegradation %	Read across from Guaiyl Acet-mono	Readily biodegradable, (80% degradation at day 28)
BIOWIN 5	0.4749	0.4749
BIOWIN 6	0.2025	0.2025