Lime (Citrus aurantifolia), ext.

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

other: see remarks

Remarks:

The result for this NCS was concluded from the constituent approach.

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Lime oil is a Natural Complex Substance (NCS). With 99 % of the constituents of Lime Oil known, this NCS can be considered as a well defined NCS. Lime oil typically consists for 44% (25-80 %) of d-limonene and a range of more or less related constituents. If the constituents of the NCS are readily biodegradable, the NCS itself is readily biodegradable as well.

Principles of method if other than guideline:

Assessment of the Ready biodegradability of the known constituents; addition of the percentage of readily biodegrabable constituents in the mixture gives the fraction of ready biodegradable substances. If this fraction exceeds 75%, the NCS is classified as 'readily biodegradable'.

GLP compliance:

no

Inoculum or test system:

other: see remarks

Remarks:

Multiple methods have been used to derive the results for the constituents.

Key result

Parameter:

other: see remarks

Remarks:

For the constituents multiple methods have been used hence multiple parameters contribute to the conclusion.

Value:

> 60

Sampling time:

28 d

Remarks on result:

other: see remarks

Remarks:

based on results of the consituents

Details on results:

Details for all constituents are summarised in window "Any other information on results" and in attached document

Assessment of the biodegradability of LIME OIL:

The majority of the constituents, totalling 89% of the composition, is readily biodegradable in experimental tests, see underlying data in table below. Seven of the remaining constituents comprising 10 % of the composition are predicted to be readily biodegradable.

Constituent	Typical %	Results of biodegradation assessment
D-limonene C10H16	44 %	READILY BIODEGRADABLE: - Headspace CO2: 71.4% (Quest 1993). The biodegradability of perfume ingredients in the sealed vessel test. - MITI (I) / OECD 301C, improved for volatile substance: Limonene 14d – BOD: 41, 81, 98% Direct analysis: GC: 100%; TOC 50, 73, 81% (MITI 1980 http://www.safe.nite.go.jp/sitemap/db_map_e.html) - Readily biodegradable (Misra, G.; Pavlostathis, S. G.; Perdue, E. M.; Araujo, R. Applied Microbiology and Biotechnology (1996), 45(6), 831-838.)
gamma-Terpinene C10H16	10 %	READILY BIODEGRADABLE - MITI (I) / OECD 301C, improved for volatile substance: 28 d - BOD: 94% Direct analysis: TOC 77%, GC: 100% (MITI 1988) Remarks: - The test substance changed partially to form p-Isopropylbenzoic acid. - Based on the results of the test substance and p-Isopropylbenzoic acid (CAS 536-66-3, Ready Biodegradable) (a product), the test substance was judged to be a substance of ready-biodegradation. http://www.safe.nite.go.jp/sitemap/db_map_e.html)   Supporting evidence from: - Readily biodegradable: aerobic, soil inoculum, disappearance of parent monitored with some supporting CO2 / biomass data (Misra, G.; Pavlostathis, S. G.; Perdue, E. M.; Araujo, R. Applied Microbiology and Biotechnology (1996) 45(6): 831-838)
alpha-Terpineol C10H18O	7 %	READILY BIODEGRADABLE: - OECD 310 Carbon Dioxide Headspace test, CO2 production: 80% degradation for Isomeric terpineol mixtures [CAS 8000-41-7] e.g. mixture containing 86% alpha, 11% gamma & 1% beta (Van Ginkel 2008).   Primary degradation and complete mineralisation demonstrated using soil inoculum under aerobic conditions (Misra, G.; Pavlostathis, S. G.; Perdue, E. M.; Araujo, R. Applied Microbiology and Biotechnology (1996), 45(6), 831-838.)
Terpinolene C10H16	6 %	READILY BIODEGRADABLE - OECD 301B (sealed): 62% (Quest 1996): - OECD 301F: 51% (Givaudan, 1997) - OECD 302C: 80% (Givaudan, 1998) - Rapid primary degradation (Misra, G.; Pavlostathis, S. G.; Perdue, E. M.; Araujo, R. Applied Microbiology and Biotechnology (1996), 45(6), 831-838.)
alpha-Terpinene C10H16	1 %	Expected to be READILY BIODEGRADABLE based on results with: g-terpinene (CAS 99-85-4) Readily biodegradable (Misra, G.; Pavlostathis, S. G.; Perdue, E. M.; Araujo, R. Applied Microbiology and Biotechnology (1996), 45(6), 831-838.)   and Terpinolene (CAS 586-62-9) (see previous row)
beta-Bisabolene C15H24	1 %	Expected to be READILY BIODEGRADABLE based on results with: Bisabolol (CAS no 23089-26-1) OECD 301F: 73% (Givaudan 2010 in Jenner et al. 2011 Env.Tox.Cehm 30(5):1096-1108)   According to UM-PPS ( http://umbbd.msi.umn.edu/predict/) the initial degradation pathways for Bisabolene are the same as for Bisabolol. Applicable rules are bt0241, bt0242 and bt 0332: hydroxylation of an aliphatic tertiary, secondary C-atom or an aliphatic methyl group, respectively. In addition for Bisabolene also rule bt0049 is identified: epoxide formation from an alkene. For all pathways the likelihood was the same (neutral).    As 1. Bisabolol was shown to be readily biodegradable, and 2. the predicted pathways for Bisabolol are also predicted for Bisabolene; Bisabolene is also expected to be readily biodegradable.
Para-Cymene C10H14	1 %	READILY BIODEGRADABLE: - OECD301F: 64% (Givaudan, 1999)   - MITI (I) / OECD 301C (improved type for a volatile substance): 14d - BOD: 88% Direct analysis: TOC 89%, GC: 100% (MITI 1987: http://www.safe.nite.go.jp/data/hazkizon/ pk_e_kizon_data_result.home_data)
beta-pinene C10H16	10 %	READILY BIODEGRADABLE: Read-across from alpha-Pinene (see next row), based on structural analogy Supporting evidence from: - OECD301B, sealed vessels Gum turpentine (50.9% alpha-pinene, 36.8% beta-pinene): 52% mineralisation in 28d (Astra Zeneca, 2001, ECB PBT#84). This high level of biodegradation cannot be caused by degradation only of alpha-pinene, so also beta-pinene is degraded.
alpha-Pinene C10H16	2 %	READILY BIODEGRADABLE: - OECD301B, sealed vessels: 62% (28d), 70% (42d) (Astra Zeneca, 2001, ECB PBT#84 http://ecb.jrc.ec.europa.eu/documents/PBT_EVALUATION/PBT_sum084_CAS_91770-80-8.pdf ) - MITI (I) / OECD 301C: 28d - BOD: 91, 90, 95% Direct analysis: GC: 100, 100, 100% (MITI 2007: http://www.safe.nite.go.jp/sitemap/db_map_e.html)
Cineoles (1,8 and 1,4) C10H18O	4 %	1,8-cineole: l READILY BIODEGRADABLE: - OECD 301B, sealed CO2: 91% (Quest, 1995) - OECD 301F: 82% (Givaudan, 1997) - OECD 301D, Closed bottle: 72% (Symrise, 2000)
alpha-Bergamotene C15H24	1 %	Expected to be READILY BIODEGRADABLE. Based on read-across from beta-Bisabolene and to alpha-Pinene that are both readily biodegradable. 1. beta-Bisabolene and alpha-Bergamotene are both sesquiterpene hydrocarbons with a ring system and similar aliphatic chain. 2. alpha-Bergamotene contains a carbon with 4 single bonds which is usually regarded to hamper the rate of degradation. Yet the alicyclic structure is resembles alpha-Pinene that also has the feature of the quaternary carbon and yet is shown to be readily biodegradable.
Sabinene C10H16	1 %	READILY BIODEGRADABLE: - OECD 301F: 76% in 28d (Givaudan 2010) Sabinene (72% pure with 27% beta-pinene)
Furocoumarins	3 %	Predicted to be READILY BIODEGRADABLE: BIOWIN v4.10 (US-EPA): BIOWIN1: 0.883; BIOWIN2: 0.9884; BIOWIN3: 2.9280 (weeks); BIOWIN4: 3.8081 (days); BIOWIN5: 0.5473; BIOWIN6: 0.5337.
5-Geranoxy-7-methoxy coumarin C20H24O4	2 %	Expected to be READILY BIODEGRADABLE: This constituent is the reaction product of Geranyl acetate and methoxycoumarin. Geranyl acetate is READILY BIODEGRADABLE: - OECD 301D: 68% (Symrise 1999) - OECD 301D: 91% (Symrise 2000) - OECD 301B: 82.2% (Quest, 1994) - OECD 301F: 85% (Givaudan, 1998)   Methoxy coumarin is expected to be READILY BIODEGRADABLE, see previous row   The constituent is expected to be also readily biodegradable based on the fact that the two sub-structure moieties (geranyl skeleton and coumarin skeleton) are readily biodegradable.
Citral C10H16O	3 %	READILY BIODEGRADABLE: - Modified 301B, sealed vessels CO2: 92.1% in 28 d (Quest 1994) - MITI (I) / OECD 301C, improved for volatile substance (Citral is mixture of neral and geranial): 28d - BOD: 92% Direct analysis: TOC: 78%; GC: 100% The test substance formed 6-Methyl-5-hepten-2-one (2-2480) and Geranic acid in (Water + Test Substance) system. (MITI 1991: http://www.safe.nite.go.jp/sitemap/db_map_e.html)
beta-Myrcene C10H16O	1 %	READILY BIODEGRADABLE: - OECD 310 Carbon Dioxide Headspace test: CO2 production: 73% (Van Ginkel 2009) - MITI (I) / OECD 301C, improved for volatile substance: 14d - BOD: 86% Direct analysis: GC: 99%; TOC: 97% (MITI 1987: http://www.safe.nite.go.jp/sitemap/db_map_e.html)
Farnesene C15H24	1 %	Expected to be READILY BIODEGRADABLE analogy to beta-Myrcene (see previous row)
Neryl Acetate C12H20O2	1 %	Expected to be READILY BIODEGRADABLE after esther cleavage, analogy to beta-Myrcene (see above)   Confirmed by prediction with BIOWIN v4.10 (US-EPA): BIOWIN1: 0.8283; BIOWIN2: 0.9866; BIOWIN3: 2.9056 (weeks); BIOWIN4: 3.7935 (days); BIOWIN5: 0.6342; BIOWIN6: 0.6744
Linalool C10H18O	0 %	READILY BIODEGRADABLE: - OECD 301C: 80% (Givaudan 1991) - OECD Modified 301B, sealed CO2: 97.1% (QUEST 1994)                               - Readily biodegradable (Misra, G.; Pavlostathis, S. G.; Perdue, E. M.; Araujo, R. Applied Microbiology and Biotechnology (1996), 45(6), 831-838.)  - MITI (I) / OECD 301C: 28d - BOD: 90% Direct analysis: TOC 99% GC: 100%; (MITI 1996 http://www.safe.nite.go.jp/sitemap/db_map_e.html)
Fraction of NCS readily biodegradable	89 %
Fraction of NCS expected to be readily biodegradable	10 %
Total of known constituents in NCS	99 %

The complete asssessment is added attached to this study record. Studies mentioned by Company Name are included in the RIFM database.

Validity criteria fulfilled:

not applicable

Interpretation of results:

readily biodegradable

Conclusions:

Lime oil is considered as readily biodegradable.

Executive summary:

Lime oil is a well defined Natural Complex Substance (NCS) for which 99 % of the constituents is identified.

The constituents of Lime oil are predominantly alicyclic unsaturated monoterpene hydrocarbons. Other constituents are alicyclic terpenoid hydrocarbons and acyclic monoterpene or terpenoid hydrocarbons. In the typical Lime oil (combined), the main constituent limonene is present at 44 %. As no valid empirical results from a test for the ready biodegradation of Lime oil are available, the assessment is based on its constituents. The assumption is that if the constituents of the NCS are readily biodegradable, the NCS itself is readily biodegradable as well.

For 89 % of the constituents the available data are obtained in tests on the ready biodegradability, whereas for 7 substances or 10% of the composition, the results are based on data for closely related substances. Thus 99% of the composition of the NCS is in the category of readily biodegradable substances. 

Therefore, Lime oil is considered as readily biodegradable. 

Description of key information

99% of the composition of this NCS is in the category of readily biodegradable substances.

Therefore, Lime oil is considered to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Lime oil is a Natural Complex Substance (NCS) which is a subgroup of Complex reaction products or Biological material (UVCB substances). With 99 % of the constituents of Lime oil (combined) known, this NCS can be considered as a well defined NCS. The constituents of Lime oil are predominantly alicyclic unsaturated monoterpene hydrocarbons. Other constituents are alicyclic terpenoid hydrocarbons and acyclic monoterpene or terpenoid hydrocarbons. In the typical Lime oil (combined), the main constituent limonene is present at 44 % with a range of 25 -80%.

The assessment of the biodegradability of Lime Oil is based on its constituents. The assumption is that if the constituents of the NCS are readily biodegradable, the NCS itself is readily biodegradable as well.

For 89 % of the constituents the available data are obtained in tests on the ready biodegradability, whereas for 7 substances or 10% of the composition, the results are based on data for closely related substances. Thus 99% of the composition of the NCS is in the category of readily biodegradable substances. 

Therefore, Lime oil is considered as readily biodegradable.