Alcohols, C9-11-branched and linear

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

01-04-1993 to 01-06-1993

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Remarks:

Guideline study conducted to GLP but some experimental details not reported.

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

not specified

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

other: no details provided on the inoculum

Duration of test (contact time):

37 d

Initial conc.:

38 mg/L

Based on:

test mat.

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

83

Sampling time:

26 d

Remarks on result:

other: average of two replicates at day 26 time point

Details on results:

The substance degraded >60% within the 10 day window, therefore it is considered readily biodegradable.

Results with reference substance:

Control substance: Sodium benzoate Kinetic of control substance: 1 days = 44%, 8 days = 83%, 26 days = 90%, 30 days = 93%, 37 days = 91%.

The following validity criteria were met (1) The oxygen uptake of the  inoculum blank was less than 60 mg/l over 28 days, (2) Parallel assays  did not differ by more than 20%, (3) reference compound reached the pass level within 14 days. No information was provided on the pH of test  system.
Kinetic of test substance:        
1 days = 17%
8 days = 66%
26 days = 83%
30 days = 84%
37 days = 85%

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

A ready biodegradation value of 83% after 26 days was obtained for the test under using a test procedure according to OECD 301F. The result is considered reliable.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1984

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Not key study: Other studies (same reliability score) but with higher degradation rate are available.

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic (adaptation not specified)

Duration of test (contact time):

28 d

Initial conc.:

2 mg/L

Based on:

test mat.

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

>= 53 - <= 54

Sampling time:

28 d

Details on results:

Kinetic of test substance (in %):
= 38 after 5 day(s)
= 54 after 15 day(s)
= 54 after 28 day(s)

The test substance degraded < 60% over the test period, therefore cannot be considered readily biodegradable.

Results with reference substance:

Kinetic of control substance:
5 days = 60%
15 days = 62%
28 days = 71%

The following validity criteria were fulfilled: 
(1) oxygen uptake in the inoculum blank did not exceed 1.5 mg/l after 28  days; 
(2) dissolved oxygen concentrations did not fall below 0.5 mg/l; 
(3) the reference substance reached the pass level by Day 14; 
(4) parallel assays did not differ by greater than 20%; 
(5) the toxicity control attained > 25% degradation in 14 days.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test substance degraded < 60% over the test period, therefore cannot be considered readily biodegradable.

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2009-03-17 to 2009-04-15

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to an appropriate OECD test guideline. It was not compliant with GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

GLP compliance:

no

Remarks:

At the time of the study, this lab was in the process of attaining formal GLP status and did not hold certification. The work was conducted in accordance with GLP-principles (personal communication, 2010) and to high quality standards.

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Fairfield Wastewater Treatment Plant, Fairfield, Ohio

- Preparation of media: The media was prepared one day prior to test initiation. The media consisted of the following reagents (1ml/l) in high quality deionised water: magnesium sulfate (2.25%), calcium chloride (2.75%), ferric chloride (0.025%) and phosphate buffer (10 ml/l). The phosphate buffer solution consisted of potassium dihydrogen phosphate (8.5 g/l), dipotassium hydrogen phosphate (21.75 g/l), disodium hydrogen phosphate dihydrate (33.4 g/l) and ammonium chloride (0.5 g/l).

- Preparation of inoculum for exposure: Activated sludge solids centrifuged for 20 minutes at 3000rpm and the supernatant decanted. Solids resuspended in media and homogenised in a blender for 1 minute. The solids were washed a second time as descripbed above and the TSS (total suspended solids) measured. Sufficient inoculum was added to the media to obtain a solids concentration of 15 mg/l. This mixture was adjusted to pH7 and aerated overnight with CO2-free air.

- Concentration of sludge: 15 mg solids/l.

Duration of test (contact time):

28 d

Initial conc.:

15.1 mg/L

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: test material, sludge inoculum and phosphate buffered media

- Solubilising agent (type and concentration if used): Trichloromethane was used as a solubilising agent. The solvent was then evaporated under a gentle stream of N2 gas to deposit the test material as a film on the walls of the vessel.

- Test temperature: 22 C




TEST SYSTEM
- Culturing apparatus: 1 litre bottles

- Number of culture flasks/concentration: 15.1 mg/l. Two replicates.


SAMPLING
- Sampling frequency: 12h

- Sampling method: Conductivity probe immersed in 1% NaOH to measure production of CO2.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes. Six replicates

- Reference substance: Sodium Benzoate. Three replicates

Parameter:

% degradation (CO2 evolution)

Value:

74.6

St. dev.:

0.4

Sampling time:

28 d

Details on results:

The final SOC levels ranged from 0.5 to 0.6 mg/l, and were <0.1 mg/L for reference substance.

Table 1: Degradation kinetics

Type of suspension	% degradation at sampling time (days)
	0	1	2	3	6	8	10	14	16	20	22	24	27	28
Test sample (mean of 2 replicates)	0	0	5.64	17.07	49.22	60.61	64.81	70.02	71.79	73.92	73.54	74.45	74.60	74.59
Reference substance (mean of 3 replicates)	0	0	26.03	41.45	68.48	76.51	79.90	81.88	82.14	82.10	82.19	81.76	81.42	81.69

 

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

A reliable study conducted according to an appropriate test protocol (OECD 301B), but not conducted according to GLP, determined the substance to be readily biodegradable (74.6% CO2 evolution in 28 days), meeting the ten day window.

Executive summary:

P&G (2009) conducted ready biodegradation screening tests on even saturated single chain length alcohols (C6-C22) using an appropriate test method (OECD 301B). Although, the test was not conducted in compliance with GLP, the study was found to be consistent with other available data, reliable and acceptable for environmental assessment. All tests substances were found to behave in a similar way. The substances were found to be readily biodegradable meeting the ten day window after a brief lag period.

Reference 4

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2002

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to an appropriate OECD test guideline. It was not compliant with GLP.

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

other: effluent of treatment plant predominantly treating domestic sewage

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Hochdahl

- Concentration of sludge: 1ml/l

- Initial cell/biomass concentration: 1000 - 100000 cells/ml

- Type and size of filter used, if any: Coarse paper filter. The first 200 ml was discarded.

Duration of test (contact time):

30 d

Initial conc.:

5 mg/L

Based on:

test mat.

Initial conc.:

2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS

- Solubilising agent (type and concentration if used): Due to the low water solubility of the test substance, a homogenous distribution was achieved by ultrasound dispersion and stabilization by an inert emulsifier. The dispersing agent was nonylphenol ethoxylate additionally propoxylated with 5 propyleneoxide units (NP 9,5 EO 5PO). The ratio of test substance to emulsifier was 1:1.

- Test temperature: 20 C

- Aeration of dilution water: Aerated by means of a sintered glass tube until 02 saturation (8-9 mg O2/l) was reached.


TEST SYSTEM

- Test volume: 292.8 - 294.5 ml

- Number of culture flasks/concentration: Six flasks for each concentration


SAMPLING

- Sampling frequency: 5, 15 and 30 d


CONTROL AND BLANK SYSTEM

- Inoculum blank: 4 for each sampling time

Reference substance:

other: Dodecylsulfate

Parameter:

% degradation (DOC removal)

Value:

88

Sampling time:

30 d

Details on results:

Kinetic of control substance:
5 days = 73%
15 days = 80%
30 days = 96%

RS-Freetext:
The test substance (2 mg/l) attained >60% degradation within the 10 day window and can therefore be considered readily biodegradable. The values reported in the results
section are for the 2 mg/l concentration. The 5 mg/ltest concentration had insufficient residual dissolved oxygen content. The following results were given, 5 day >53%; 15 day >60%; 30 day >60%.

Kinetic of test substance (in %):
= after 5 day(s)
= 74 after 15 day(s)
= 88 after 30 day(s)

Table 1: Degradation kinetics

Type of suspension	Vessel no.	mg oxygen/l after X-days
		0	5	15	30
Blank (inoculated test medium)	b1	-	8.56	8.28	7.54
	b2	-	8.46	8.40	8.13
	b3	-	8.47	8.33	8.59
	b4	-	8.47	8.41	5.84
	mean	9.23	8.49	8.36	7.52
Reference substance	r1	-	5.54	5.21	3.53
	r2	-	5.58	5.10	3.83
	mean	9.23	5.56	5.16	3.68
Blank emulsifier (inoculated test medium plus emulsifier at 2mg/l)	LV1	-	8.51	8.43	8.46
	LV2	-	8.49	8.43	8.80
	mean	-	8.50	8.43	8.63
Blank emulsifier (inoculated test medium plus emulsifier at 5mg/l)	LV3	-	8.55	8.41	8.35
	LV4	-	8.54	8.52	8.59
	mean	-	8.55	8.46	8.47
Test sample 2 mg/l	P1	-	4.42	3.69	3.46
	P2	-	4.42	3.73	2.67
	mean	9.23	4.42	3.71	3.06
Test sample 5 mg/l	P3	-	0.10	0.07	0.04
	P4	-	0.11	0.11	0.00
	mean	9.23	0.11	0.09	0.02

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

A reliable study conducted according to an appropriate test protocol (OECD 301D), but not conducted according to GLP, determined the substance to be readily biodegradable (88% DOC removal in 30 days), meeting the ten day window.

Executive summary:

A reliable study conducted according to an appropriate test protocol (OECD 301D), but not conducted according to GLP, determined the substance to be readily biodegradable (88% DOC removal in 30 days), meeting the ten day window.

Description of key information

Readily biodegradable based on 83% (Manometric Respirometry Test) in 26 days (OECD 301F) for undecanol, branched and linear;

Read-across values from C10 and C12 linear alcohols: 88% (DOC removal) in 30 d (OECD 301D; not GLP); 74.6% (CO2) in 28 days and 69.0% (CO2) in 28 days (OECD 301B; not GLP); and 79% (DOC removal) in 28 d (OECD 301D, GLP) based on weight of evidence. Read-across values from a C11 branched and linear alcohol: 83% in 26d and >60% within the 10-day window (OECD 301F).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The most recent standard reliable study which was read across from a branched and linear undecanol test material contains significant and useful results. This study gave results of 83% in 26 days (OECD 301F) (readily biodegradable) (Istituto Guido Donegani 1993). In a supporting study, a ready biodegradation of 64 - 79% (OECD 301B) was obtained for a mixed alcohol test substance comprised of chain lengths C7-9 (Shell, 1984).  Similarly, ready biodegradation was determined based on degradation of 88% in 30 days (Richterich, 2002) and 74.6% in 28 days (Federle, 2009) using OECD 301D and OECD 301B respectively for tests with decan-1-ol as a representative constituent. The read across is justified on the basis of structural feature and similar environmental property which is common to the alcohols in this category.

However, in a non reliable study, a ready biodegradation of 79% (OECD 301B) was obtained for the test substance, the study was disregarded because the inoculum was acclimated before use (Shell, 1979).

The test substance is found to be readily biodegradable on the basis of available data.

The Category hypothesis is that the long chain linear aliphatic alcohol family has at its centre an homologous series of increasing carbon chain length, which is associated with a consistency and predictability in the property data across the group, for the physicochemical, environmental, and toxicological property data sets.

Many biodegradation assays have been carried out on this family of alcohols. The best quality data (Klimisch reliability score of 1 or 2) were generated on single carbon chain length alcohols for tests that conform most closely to ready test biodegradability methods (OECD 301 series). In all cases the inoculum was not acclimated. While some of these results are not performed with GLP, they are reliable data. These data show that alcohols with chain lengths up to C22 are readily biodegradable. Older reliable data suggest that chain lengths above C18 are not readily biodegradable, however those studies used loading techniques which while in general is still reliable, did not make allowance for the reduced bioavailability caused by the low water solubility of these highest chains. Where the substances are introduced into the test vessels by coating onto the flask, very rapid biodegradation was confirmed at all chain lengths tested.

A reliable study (Federle, 2009), conducted according to an appropriate test protocol (OECD 301B), but not conducted according to GLP, determined decanol (C10) and dodecanol (C12) to be readily biodegradable, meeting the ten day window. Trichloromethane was used as a solubilising agent in this study. The solvent was then evaporated under a gentle stream of N₂ gas to deposit the test material as a film on the walls of the vessel.

This study (Federle, 2009), using a methodology with appropriate loading method for the low solubility of the substances, was carried out with a range of linear saturated alcohols from four carbon chain length (C4) to twenty-two carbon chain length (C22).

These results are significant and fit for purpose even though the study was not conducted to GLP. The study gave results of 76.1% (C4), 77.7% (C6), 77.9% (C8), 74.6% (C10), 69.0% (C12), 82.2% (C14), 82.4% (C16), 95.6% (C18), 88.4% (C20) and 87.9% (C22) in 28 days. All were readily biodegradable, meeting the ten-day window.

A second reliable study (Richterich, 2002), conducted according to an appropriate test protocol (OECD 301D), but not conducted according to GLP, determined decanol to be readily biodegradable (88% DOC removal in 30 days), meeting the ten day window. Due to the low water solubility of the test substance, a homogenous distribution was achieved by ultrasound dispersion and stabilisation by an inert emulsifier. The dispersing agent was nonylphenol ethoxylate.

A third reliable study (Werner, 1993), conducted according to an appropriate test protocol (OECD 301D), and in accordance with GLP, determined dodecanol to be readily biodegradable (79% DOC removal in 28 days), during the 14-day window. Due to the low water solubility of the test substance, a homogenous distribution was achieved by stabilisation with an inert emulsifier. The dispersing agent was nonylphenol ethoxylated propoxylated and is not thought to have significantly affected the test result.

A fourth reliable study (Istituto Guido Donegani, 1993) conducted according to an appropriate test protocol (OECD 301F) and in accordance with GLP, determined undecanol, branched and linear to be readily biodegradable (83% in 26 days and >60% within the 10-day window).

These four reliable studies are used as Weight of Evidence.

Other supporting studies are also available:

- A summary report from a BODIS test reports dodecanol to be readily biodegradable in 10 d window (100% in 28 days O2 consumption) (Henkel, 1992)

- A summary report for a BODIS test reports decanol to be readily biodegradable (77% in 30 days O2consumption) (Henkel, 1999).

- A summary report from a BODIS test equivalent to the OECD 301B determined dodecanol to be readily biodegradable in a 10-day window (71% in 28 days CO2 evolution) (Vista Chemical Company, 1991)

- A study conducted according to an appropriate test protocol (OECD 301B, not GLP) reports dodecanol to be readily biodegradable in a 10-day window (66% in 28 days CO2 evolution) (Vista Chemical Company, 1991)

The conclusion of ready biodegradability is consistent with evidence of rapid metabolism of long-chain fatty alcohols in fish, mammals and microorganisms (see IUCLID Sections 5.3.1, 7.1 and 6.1.4).

Other reliable studies (Jenkins 1996a for C10; Mead 1997 and Vista Chemical Company 1994 for C10 and C12), conducted according to appropriate test protocols (OECD 301B and TSCA test guideline CFR 40 part 796.3100), determined decanol and dodecanol to be not readily biodegradable (For C10; 29% CO2 evolution in 29 days and 50% in 28 days CO2 evolution, respectively, and for C12; 41,01% in 31 days CO2 evolution). The results from these studies are considered as unexplained outliers.

It is quite normal to observe some inter-laboratory variation in screening studies, particularly for substances where solubility limits may be a factor in degradation rates under the conditions of the testing. Due to the very diluted nature of the inoculum and its limited size, it may sometime happen that no degradation-competent microorganisms are present in a particular inoculum. This is evidenced by the variable mineralisation levels seen for standard reference substances under the conditions of OECD 301 (e.g. glucose, 55-90%; benzoates 61-95%) in studies collated by AISE/CESIO [AISE/CESIO company data, and the 'Study on the possible problems for the aquatic environment related to surfactants in detergents' (WRc Ref EC4294, May 1997)].

In the case where multiple reliable studies exist showing a range of extent of biodegradation in the course of standard tests, the normal approach is to base the interpretation on the higher degradation results, this is in line with ECHA guidance on information requirements and chemical safety assessment. An important piece of additional evidence to consider is the availability of ready biodegradation data from a series of tests conducted at the same laboratory at the same time, to examine degradability throughout the series of linear alcohols from C4-C22. Whilst at the time of the study by Federle (2009), the laboratory was not GLP-certified, the data are reliable and consistent throughout the homologous series. In this study (Federle, 2009) all chain lengths studied were found to be readily biodegradable. For these reasons, these study results are disregarded.

In addition to the three reliable standard protocol ready biodegradation studies mentioned earlier, two 5-day biochemical oxygen demand studies are available for C10 and C12 (Vaishnav 1987 and Jenkins 1996).

REACH Guidance (Chapter R7b) states the following regarding this type of test:

"Information on the 5-day biochemical oxygen demand (BOD5) can be used for classification purposes only when no other measured degradability data are available. Thus, priority is given to data from ready biodegradability tests and from simulation studies regarding degradability in the aquatic environment. The BOD5 test is a traditional biodegradation test that is now replaced by the ready biodegradability tests. Therefore, this test should not be performed today for assessment of the ready biodegradability of substances. Older test data may, however, be used when no other degradability data are available".

These BOD5 studies are therefore selected as supporting studies. Both studies indicate not readily biodegradable based on a BOD5/COD ratio of <0.5.

Discussion of trends in the Category of C6-24 linear and essentially-linear aliphatic alcohols:

Many biodegradation assays have been carried out on this family of alcohols. Studies generated on single carbon chain length alcohols for tests that conform most closely to ready test biodegradability methods (OECD 301 series) show that alcohols with chain lengths up to C22 are readily biodegradable. In all cases the inoculum was not acclimated. Older reliable data suggest that chain lengths above C18 are not readily biodegradable, however those studies used loading techniques which, while in general still reliable, did not make allowance for the reduced bioavailability caused by the low water solubility of these longest chain substances. Where the substances are introduced into the test vessels by coating onto the flask, very rapid biodegradation was confirmed at all chain lengths tested.

In the older supporting tests, alcohols with chain lengths up to C18 are readily biodegradable. At carbon chain lengths = 14, most tests showed that pass levels for ready biodegradation were reached within the 10 day window. Chain lengths of C16-18 achieved ready test pass levels, but not within the 10 day window. The one test on a single carbon chain length greater than C18 (using docosanol) showed degradation of 37%.

Tests which allowed adaptation are considered to have significant methodological deficiencies in terms of REACH requirements for the present purpose, and are accordingly considered to be Klimisch reliability 3: Invalid. However these also consistently demonstrate extensive biodegradability. Aliphatic alcohols occur naturally in the environment and environmental organisms will be acclimated.

Reliable studies for decanol and tetradecanol that show low levels of degradation are considered to be unexplained outliers. It is usual in the interpretation of such data to take the highest levels of degradation as the key study.

Federle, (2009) conducted ready biodegradation screening tests on even-numbered saturated single chain length alcohols (C6-C22) using an appropriate test method (OECD 301B). Although, the test was not conducted in compliance with GLP, the study was found to be consistent with other available data, reliable and acceptable for environmental assessment. All tests substances were found to behave in a similar way. The substances were found to be readily biodegradable meeting the ten day window after a brief lag period. A separate test using the same methodology has confirmed the ready biodegradability result, meeting the ten-day window, at the upper end of the carbon number range (docosan-1-ol) in a GLP-compliant study (Flach, 2012).

Some variability is seen in the ultimate percentage degradation over the course of the study (see Table 1 below). It is quite normal to observe some inter-laboratory variation in screening studies, particularly for substances where solubility limits may be a factor in degradation rates under the conditions of the testing. As discussed above, due to the very diluted nature of the inoculum and its limited size, it may sometime happen that no degradation-competent microorganisms are present in a particular inoculum. This is evidenced by the variable mineralisation levels seen for standard reference substances under the conditions of OECD 301. In the case where multiple reliable studies exist showing a range of extent of biodegradation in the course of standard tests, the normal approach is to base the interpretation on the higher degradation results, this is in line with ECHA guidance on information requirements and chemical safety assessment, and consistent with the availability of ready biodegradation data from a series of tests conducted at the same laboratory at the same time, to examine degradability throughout the series of linear alcohols from C6-C22. Whilst at the time of the study (Federle, 2009), the laboratory was not GLP-certified, the data are reliable and consistent throughout the homologous series. In this study (Federle, 2009) and all other chain lengths studied were found to be readily biodegradable.

Biodegradation under anaerobic conditions

The anaerobic biodegradability of a range of chain lengths within the category has been investigated (C8, C16 alcohols (two studies), and C16-18 and C18 unsaturated alcohols). All test substances were anaerobically degradable. Results from available studies are presented in Table 2 below.

Biodegradation by algae

Rapid degradation in water is indicated by the difficulties encountered in aquatic toxicity tests (chronic Daphnia reproduction) for long chain aliphatic alcohols (Section 6.1.4). Alcohols in the range C10-C15 were found to be rapidly removed from the test medium. This was attributed to metabolism by algae present as a food source in tests, and in later stages of the 21-day tests to bacterial degradation by microbes adsorbed onto the carapace of the test daphnids, despite daily cleaning of the animals.

Natural occurrence

It is important for context to note the findings from studies in the EU and US which consistently show that anthropogenic alcohols in the environment are minimal compared to the level of natural occurrence. Using stable isotope signatures of fatty alcohols in a wide variety of household products and in environmental matrices sampled from river catchments in the United States and United Kingdom, Mudge et al. (2012) estimated that 1% or less of fatty alcohols in rivers are from waste water treatment plant (WWTP) effluents, 15% is from in situ production (by algae and bacteria), and 84% is of terrestrial origin. Further, the fatty alcohols discharged from the WWTP are not the original fatty alcohols found in the influent. While the compounds might have the same chain lengths, they have different stable isotopic signatures (Mudge et al., 2012).

In conclusion, the environmental impact of these studies is that it has confirmed that the fatty alcohols entering a sewage treatment plant (as influent) are partly derived from detergents, but these are not the same alcohols as those in the effluent which arise from in-situ bacterial synthesis. In turn, the fatty alcohols found in the sediments near the outfall of the WWTP are derived from natural synthesis and are not the same alcohols as those in the effluent.

Ready biodegradation data on single constituent alcohols

CAS	Chemical Name	Comment	Method	Result % degradation	Result 10 day window	Reliability	Reference
111-27-3	1-Hexanol		301B	77.7% in 28 days at 17 mg/L	69.8%	2	Federle 2009
111-27-3	1-Hexanol		OECD 301-D	77% in 30 days at 2 mg/L 61% in 30 days at 5 mg/L	>60% in 14 days	2	Richterich, 2002a
111-27-3	1-Hexanol		Non-standard	- half life of 8.7 hours	-	2	Yonezawa and Urushigawa 1979
111-87-5	1-Octanol		301B	77.9% in 28 days at 18.8 mg/L	79.2%	2	Federle 2009
111-87-5	1-Octanol		ISO ring test (CO2 headspace biodegr. test)	92% in 28 days at 20 mg/L	>60%	2	Procter & Gamble, 1996
111-87-5	1-Octanol		OECD 301-B	59 % in 29 days at 10 mgC/L	-	2	Huntingdon Life Sciences Ltd. 1996a
111-87-5	1-Octanol		Non-standard	- half life of 1.9 hours	-	2	Yonezawa and Urushigawa 1979
112-30-1	1-Decanol			74.6% in 28 days at 15.1 mg/L	68.6%	2	Federle 2009
112-30-1	1-Decanol		301-D	88% in 30 days at 2 mg/L	>60%	2	Richterich, 2002c
112-30-1	1-Decanol		301-B	29 % after 29 day(s) at 10 mg/L COD	-	2	Huntingdon Life Sciences Ltd. 1996b
112-53-8	1-Dodecanol		301B	69% in 28 days at 15.4 mg/L	63%	2	Federle 2009
112-53-8	1-Dodecanol	Supporting	301-D	79% in 28 days at 2 mg/L	>60% in 14 days	1	Werner, 1993
112-72-1	1-Tetradecanol		301B	82.2% in 28 days at 15.9 mg/L	77.2%	2	Federle 2009
112-72-1	1-Tetradecanol		BODIS ~ISO 10708	92% in 28 days at 100 mg/L COD	>60%	1	Henkel, 1992d
112-72-1	1-Tetradecanol		301-B	28 % after 28 day(s) at 25.4 mg/L	-	1	Mead 1997b
36653-82-4	1-Hexadecanol		301B	82.4% in 28 days at 15.3 mg/L	75.2%	2	Federle 2009
36653-82-4	1-Hexadecanol		301B	62% after 28 days at 17.1 mg/L	<60%	1	Mead, 1997c
36653-82-4	1-Hexadecanol		BODIS	76 % after 28 day(s) at 100 mg/L COD	<60% after 14 d	2	Henkel KGaA 1992a
112-92-5	1-Octadecanol		301B	95.6% in 28 days at 14.5 mg/L	90.2%	2	Federle 2009
112-92-5	1-Octadecanol	Supporting	301D	38% in 29 days at 5 mg/L 69% in 29 days at 2 mg/L	<60%	1	Henkel, 1992f
629-96-9	1-Eicosanol		301B	88.4% in 28 days at 15.6 mg/L	83.4%	2	Federle 2009
661-19-8	1-Docosanol		301B	87.5% in 28 days at 20 mg/L	75.6%	1	Flach, 2012
661-19-8	1-Docosanol		301B	87.9% in 28 days at 15.3 mg/L	83%	2	Federle 2009
661-19-8	1-Docosanol		301B	37% after 28 days at 12.4 mg/L	<60%	1	Mead, 2000

Anaerobic degradation of alcohols

CAS	Chemical name	Comment	Method	Source of sludge	Concentration of test substance	Duration	% degradation at end of test	Reliability	Reference
111-87-5	1-Octanol		Serum bottle, gas production + GC analysis	1oor 2odigesters	50µg/ml	8 weeks	>75%	2	Shelton and Tiedje, 1984
36653-82-4	1-Hexadecanol		Batch test using14C labelled test material	Municipal digester sludge fortified with activated sludge	1 mg/L	28 days	90%	2	Nuck and Federle, 1996
36653-82-4	1-Hexadecanol		Batch test using14C labelled test material	Municipal sewage digester	10 mg/L	28 days	97%	2	Steber and Wierich, 1987
68002-94-8	Alcohols, C16-18 and C18 unsaturated	Supporting	ECETOC screening test	Municipal sewage digester	50 mg/L	8 weeks	89%	2	Steberet al. 1995

A study by Rorije et al. (1998) on structural requirements for anaerobic biodegradation of organic chemicals is relevant. The study used a computer-automated structure evaluation program (MCASE) to analyse rates of aquatic anaerobic biodegradation of a set of diverse organic compounds, and developed a predictive model. Primary alcohols were one of the most important fragments linked to biodegradability (biophore). The authors discuss how the presence of a biophore indicates a possible site of attack for microbes to follow a metabolic pathway for anaerobic biodegradation.

Biodegradation in STP-simulation tests

Other recent data on ethoxylated alcohols also suggest that the rate of degradation could be higher than usually assigned to readily-biodegradable substances. In an OECD 303A study of the fate of alcohol ethoxylate homologues in a laboratory continuous activated sludge unit (Wind,et al., 2006) useful data about the properties and environmental exposures of alcohols are presented, although the paper describes mainly the properties of alcohol ethoxylates (AE). The waste water organisms were exposed principally to ethoxylates, but the alcohols would be generated by the degradation of the ethoxylates. The test substance comprised a 2:1 mixture of two commercial alcohol ethoxylate surfactants with chain lengths of C12-C15 (odd and even numbered) and C16-C18 (even numbered), respectively. The test substance was dosed at a concentration of 4 mg/L in the influent.

 

Results are shown in the Table below:

Removal of alcohols during an activated sludge test on alcohol ethoxylates.

Alcohol	Conc in effluent ng/L	Conc in sludge µg/g	%removal
C12	18	0.6	98.6
C13	21	0.7	99.5
C14	5.5	0	99.6
C15	2.9	1.1	99.8
C16	1.6	0.01	99.5
C18	58	0.7	99.1
Total	130	2	99.4

 

This shows that most of the alcohol which does not degrade (itself a small amount) was found in the solids in recovery at the end of the study. This study is important in that it indicates that the extent of removal of alcohols is high, from an exposure route that can realistically be anticipated based on the known life cycle.

References:

EU Commission, DGIII, Study on the possible problems for the aquatic environment related to surfactants in detergents, WRc, EC 4294, February, 1997

Flach, F., 2012. Biodegradability in the CO2-evolution test according to OECD 301b (July 1992). Hydrotox laboratory, report number 737, company study number 8571, Sasol, 2 May 2012.

Mudge, S.M, Deleo, P.C., Dyer, S.D. (2012). Quantifying the anthropogenic fraction of fatty alcohols in a terrestrial environment. Environmental Toxicology and Chemistry, Vol. 31, No. 6, pp. 1209–1222.

Nuck, B.A. and Federle, T.W. 1996. Batch test for assessing the mineralization of 14C-radiolabeled compounds under realistic anaerobic conditions. Environ. Sci.. 30:12, 3597-3603.

Rorije E, Peunenburg WJGM, Klopman G (1998) Structural requirements for anaerobic biodegradation of organic chemicals: A fragment model analysis. Environmental Toxicology and Chemistry, Vol. 17, No. 10, pp. 1943 -1950.

Shelton, D.R. and Tiedje, J.M. 1984. General method for determining anaerobic biodegradation potential. Applied and Environmental Microbiology 850-857.

Steber, J., Herold, C.P. and limia, J.M. 1995. Comparative evaluation of anaerobic biodegradability of hydrocarbons and fatty derivatives currently used as drilling fluids. Chemosphere 31:4, 3105-3118.

Steber, J. and Wierich, P. 1987. The anaerobic degradation of detergent range fatty alcohol ethoxylates. Studies with 14C-labelled model surfactants. Water Research. 21:6, 661-667.

Wind, T., R.J. Stephenson, C.V. Eadsforth, A. Sherren, R. Toy. (2006) Determination of the fate of alcohol ethoxylate homologues in a laboratory continuous activated sludge unit. Ecotox and Environ Safety, 64: 42-60.

Federle (2009). Ready Biodegradability Test, The Procter and Gamble Co., Study number65522, 27thApril 2009

Richterich, K. 2002a. 1-Hexanol: Ultimate biodegradability in the closed bottle test.Final report R 0200259.

Yonezawa, Y. and Urushigawa, Y. 1979. Chemico-biological interactions in biological purification systems. V. Relation between biodegradation rate constants of aliphatic alcohols by activated sludge and their partition coefficients in a 1-octanol-water system. Chemosphere 3:139-142.

Procter & Gamble. 1996. Final report: ISO ring test CO2 headspace biodegradation test. Study ECM ETS 554/02.

Huntingdon Life Sciences Ltd. (HLS). 1996a. Report No. 96/KAS217/0325.

Richterich, K. 2002c.Final report R 0200257.

Huntingdon Life Sciences Ltd.(HLS).1996b. Report No. 96/KAS223/0327.

Richterich. 1993. 1-Dodecanol: Aerobic biodegradation: Closed bottle test. Biological Research and Product Safety/Ecology: Unpublished results; test substance registration no. SAT 910724, Henkel KGaA; Report No. RE 920247 (With English summary report no. R9901416)

Henkel KGaA.1992d.  Report No. 920026 (test substance registration no. SAT 910723, test run no. 118).5 Marz 1992.

Mead, C. 1997b. Safepharm Laboratories, SPL Project Number 140/598.

Mead, C. 1997c. Safepharm Laboratories, SPL Project Number 140/543.

Henkel KGaA. 1992a.Biological Research and Product Safety/Ecology: Report No. RE 920102; test substance registration No. SAT 910721, test run No. 120.26 Juni 1992.

Henkel KGaA.1992f. Report No.RE920246, 18 December 1992.

Mead, C. 2000. Safepharm Laboratories, SPL Project Number 140/1002.