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Biodegradation in water and sediment: simulation tests

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Endpoint:
biodegradation in water and sediment: simulation testing, other
Remarks:
simulation testing in water and sediment
Type of information:
other: related information taken from the ECHA SVHC support document of anthracene oil
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Remarks:
data taken from the ECHA SVHC support document of anthracene oil
Principles of method if other than guideline:
The SVHC support document reviews and reports data relevant for the assessment of biodegradation of anthacene oil.
Specific details on test material used for the study:
In the SVHC support document, 9 PAHs are listed as relevant constituents of anthracene oil. A selection of these are included in the assessment of biodegradation. These are acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene.
CAS no.
1. Phenanthrene 85-01-8
2. Anthracene 120-12-7
3. Fluorene 86-73-7
4. Fluoranthene 206-44-0
5. Acenaphthene 83-32-9
6. Pyrene 129-00-0
7. Carbazole 86-74-8
8. Dibenzofuran 132-64-9
9. Benzo[a]pyrene 50-32-8
Oxygen conditions:
other: various
Inoculum or test system:
other: various
Key result
Compartment:
water
DT50:
ca. 5 - ca. 13 d
Temp.:
20 °C
Remarks on result:
other: substance acenaphthene; estimate based on model calculations
Key result
Compartment:
water
DT50:
ca. 13 - ca. 42 d
Temp.:
20 °C
Remarks on result:
other: substance fluorene; estimate based on model calculations
Key result
Compartment:
water
DT50:
ca. 13 - ca. 42 d
Temp.:
20 °C
Remarks on result:
other: substance phenanthrene; estimate based on model calculations
Key result
Compartment:
water
DT50:
ca. 13 - ca. 42 d
Temp.:
20 °C
Remarks on result:
other: substance anthracene; estimate based on model calculations
Key result
Compartment:
water
DT50:
ca. 13 - ca. 42 d
Temp.:
20 °C
Remarks on result:
other: substance fluoranthene; estimate based on model calculations
Key result
Compartment:
water
DT50:
ca. 42 - ca. 125 d
Temp.:
20 °C
Remarks on result:
other: substance pyrene; estimate based on model calculations
Key result
Compartment:
sediment
DT50:
ca. 125 - ca. 420 d
Temp.:
20 °C
Remarks on result:
other: substance acenaphthene; estimate based on model calculations
Key result
Compartment:
sediment
DT50:
ca. 420 - ca. 1 250 d
Temp.:
20 °C
Remarks on result:
other: substance fluorene; estimate based on model calculations
Key result
Compartment:
sediment
DT50:
ca. 420 - ca. 1 250 d
Temp.:
20 °C
Remarks on result:
other: substance phenanthrene; estimate based on model calculations
Key result
Compartment:
sediment
DT50:
ca. 420 - ca. 1 250 d
Temp.:
20 °C
Remarks on result:
other: substance anthracene; estimate based on model calculations
Key result
Compartment:
sediment
DT50:
> 1 250 d
Temp.:
20 °C
Remarks on result:
other: substance fluoranthene; estimate based on model calculations
Key result
Compartment:
sediment
DT50:
> 1 250 d
Temp.:
20 °C
Remarks on result:
other: substance pyrene; estimate based on model calculations
Transformation products:
not specified

Excerpt from SVHC support document

 

Biodegradation

 

Biodegradation estimation

 

The PAH listed in Table 5 were allocated to persistence classes on the basis of model calculations (Mackay et al., 1992). These half-lives were used in the Annex XV transitional report of coal tar pitch, high temperature (The Netherlands - Bureau REACH, 2009).

 

Table 5: Ranking of PAH in different half-life classes (The Netherlands - Bureau REACH, 2009)

 

Compound

Water

Soil

Sediment

 

Class

Half-life [d]

Class

Half-life [d]

Class

Half-life [d]

Acenaphthene

3

5 - 13

5

42 - 125

6

125 - 420

Fluorene

4

13 - 42

6

125 - 420

7

420 - 1250

Phenanthrene

4

13 - 42

6

125 - 420

7

420 - 1250

Anthracene*

4

13 - 42

6

125 - 420

7

420 - 1250

Fluoranthene

4

13 - 42

7

420 - 1250

8

> 1250

Pyrene

5

42 - 125

7

420 - 1250

8

> 1250

*adopted from Ref. European Commission (2008), Table 3.25 and 3.24, p. 67

 

[…]

 

Summary and discussion of persistence

Anthracene, which is one relevant constituent of anthracene oil, has been placed on the Candidate List due to the identification as a PBT-substance (European Chemicals Agency, 2008d).

Moreover, anthracene oil consists of further not readily biodegradable PAH constituents. Model calculations by Mackay et al. (1992) indicate that acenaphthene, fluorene, phenanthrene, fluoranthene, and pyrene show a half-life in sediment of more than 180 days.

Screening studies (OECD TG 301C) revealed, that phenanthrene, acenaphthene, fluorene, carbazole, and dibenzofuran as representative constituents of anthracene oil are not readily biodegradable (MITI-List, 2002).

[…]

Hence, several constituents of anthracene oil fulfil the P and/or the vP criteria according to Annex XIII of the REACH regulation.

End of excerpt

 

References

European Commission (2008) European Union Risk Assessment Report, Coal Tar Pitch High Temperature, CAS No: 65996-93-2, EINECS No: 266-028-2

The Netherlands - Bureau REACH. 2009. Annex XV transitional report: coal tar pitch, high temperature (CTPHT). URL: https://echa.europa.eu/documents/10162/ef47ccc5-0786-4bf5-b16c-2f13c6c49385

European Chemicals Agency. 2008d. Support document for identification of anthracene as a substance of very high concern. ECHA, 1-27. URL: https://echa.europa.eu/documents/10162/f7c1321a-6709-40d6-b683-1fb870fb0ac4

Mackay D, Shiu WY, Ma K. 1992. Illustrated handbook of physical-chemical properties and environmental fate for organic chemicals. Vol. II: Polynuclear aromatic hydrocarbons, polychlorinated dioxins and dibenzofurans. Lewis Publishers, Chelsea.

MITI-List. 2002. Biodegradation and Bioaccumulation of Existing Chemical Substances under the MITI-List. 2002. Biodegradation and Bioaccumulation of Existing Chemical Substances under the Chemical Substance Control Law. National Institute of Technology and Evaluation, Japan. Chemical Substance Control Law. National Institute of Technology and Evaluation, Japan.

 

More extensive data on the biodegradation properties of individual constituents of anthracene oil are available in the SVHC documents of these compounds (see study records under this endpoint). According to the current composition of anthracene oil (composite sample 7), most relevant constituents with regard to biodegradation are phenanthrene, anthracene, fluoranthene, and pyrene based on their intrinsic properties to be expected and on their abundance in anthracene oil.

Validity criteria fulfilled:
not applicable
Conclusions:
Based on biodegradation data of its PAH constituents, biodegration in water and sediments of anthracene oil is determined to be slow. At least for sediment, half-lives of constituents exceed the vP criterion of REACH regulation, Annex XIII, which identifies anthracene oil itself not to meet the vP criterion.
Endpoint:
biodegradation in water and sediment: simulation testing, other
Remarks:
simulaton testing in water and sediment
Type of information:
other: related information taken from the ECHA SVHC support document for phenanthrene, the most abundent constituent of anthracene oil
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Remarks:
information taken from the ECHA SVHC support document for phenanthrene, the most abundant constituent of anthracene oil
Principles of method if other than guideline:
The SVHC support document reviews and reports data relevant for the assessment of biodegradation of phenanthrene, the most abundant constituent of anthracene oil.
Specific details on test material used for the study:
Substance is specified by EC and CAS number. Data reported relate to this substance.
Oxygen conditions:
other: various
Inoculum or test system:
other: various
Key result
Compartment:
water
DT50:
ca. 12.5 - ca. 42 d
Temp.:
20 °C
Remarks on result:
other: estimate based on model calculations by Mackay (1992) (see below under "Any other information on results incl. tables)
Key result
Compartment:
sediment
DT50:
216 - 319 d
Temp.:
12 °C
Remarks on result:
other: recalculated (SVHC document) from experimental values obtained in experiments at 20 °C
Transformation products:
not specified

Excerpt from SVHC support document

 

Biodegradation

 

Biodegradation in water and Sediment

Regarding the biodegradation in water, as assessed in the Support Document for identification of CTPHT as SVHC (ECHA, 2009):

Experimental information for biodegradation in water has demonstrated that PAH substances with up to four aromatic rings are biodegradable under aerobic conditions, but that biodegradation rates of PAHs with more than four aromatic rings, are very low (The Netherlands, 2008).

In general, the biodegradation rates decrease with increasing number of aromatic rings. This correlation has been attributed to factors like the bacterial uptake rate and the bioavailability. The bacterial uptake rate has been shown to be lower for the higher molecular weight PAHs as compared to the PAHs of lower molecular weight. This may be due to the size of high molecular weight members, which limits their ability to cross cellular membranes. In addition, bioavailability is lower for higher molecular PAHs due to adsorption to organic matter in water and sediment. It has further been shown that half-lives of PAHs in estuarine sediment are proportionally related to the octanol-water partition coefficient (Kow) (Durant et al, (1995) cited in The Netherlands, 2008). […]

The results from standard tests for biodegradation in water show that PAHs with up to four aromatic rings are biodegradable under aerobic conditions but that the biodegradation rate of PAH with more aromatic rings is very low (ECHA, 2009). Regarding biodegradation on sediments, although there is evidence for anaerobic transformation, PAHs are usually considered to be persistent under anaerobic conditions (Neff, 1979; Volkering & Breure, 2003, cited in The Netherlands, 2008), thus a low biodegradation of phenanthrene is expected in sediments.

Although the biodegradation pathway of the different PAHs is very similar, their biodegradation rates differ considerably. In general, the biodegradation rates decreases with increasing number of aromatic rings. Biodegradation rates also are extremely dependent on the (a)biotic conditions, both in the lab and in the field. Important influencing factors are (1) the substrate concentration; with low PAH concentrations leading to longer half-lives; (2) temperature, which reversely relates to the half-live and (3) the presence or absence of a lag phase (De Maagd, 1996). In addition, the desorption rate of PAHs appears to decrease with increase of the residence time of PAHs due to slow sorption onto micropores and organic matter, and polymerisation or covalent binding to the organic fraction. The consequence of this aging process is a decreased biodegradability and a decreased toxicity (Volkering and Breure, 2003).

As assessed in the Support Document for identification of CTPHT as SVHC (ECHA, 2009) Mackay et al. (1992) estimated half-lives in the different environmental compartments based on model calculations and literature research. The calculated half-lives of phenanthrene in water and sediments are in the range of 12 to 42 days and longer than 420 to 1250 days respectively.

In a 28 day ready biodegradability test (MITI I, OECD 301C) using 100 mg/L PAHs and 30 mg/L sludge, phenanthrene did not fulfil the criteria to be considered as readily biodegradable (54% degradation after 4 weeks based on BOD measurement), similarly to fluorene, carbazole, acenaphthene and dibenzofuran. According to the MITI test, which is suitable for substances with low water solubility, these PAHs are not considered as readily biodegradable (CITI, 1992, INERIS, 2010).

Contrarily to this result, in a ready biodegradability test performed according to the OECD 301C (MITI) guideline methodology, using 100 mg/L PAHs and 30 mg/L sludge, phenanthrene achieved 67.2% mineralisation (BOD/ThOD) over 28 days (Junker et al., 2016).

As stated in the R.11 ECHA guidance, “Available data consisting solely of screening information can be employed to derive a conclusion mainly for “not P and not vP” or “may fulfil the P or vP criteria”. After the latter conclusion on screening, higher tier information generally needs to be made available. Appropriate data need to be available to conclude the P/vP-assessment with a conclusion “not P/vP” on all three compartments (or five, with marine compartments): water (marine water), sediment (marine sediment) and soil. Either the available data, including in normal case simulation test data from one or two compartments, can be interpreted so that a conclusion can be derived on the remaining compartment(s) for which no higher tier data are available, or data need to be available directly on all compartments, or there is another justification for why a conclusion does not need to be drawn for all three (five) compartments. Moreover, “the conclusion should be based on a Weight-of-Evidence consideration by expert judgement where all relevant and available data for all endpoints are considered in conjunction”. As data were available for other compartments than water, these data need to be taken into account in a Weight-of-Evidence consideration for the persistency assessment of phenanthrene.

[…]

In a microcosm study (Bahr et al., 2015), the biodegradation of four PAHs (naphthalene, fluorene, phenanthrene, and acenaphthene added as 13C-labelled substrates) was investigated as single substances in groundwater (pH around 7) from an aquifer located at the site of a former gas plant with oxic conditions. 13CO2-values of controls amended with non-labelled phenanthrene shifted from -20‰ to -27‰, while the sterile controls remained stable. There is no information on the effect of pre-adaptation on biodegradation in this study. 13C-enrichment of the produced CO2 revealed mineralisation of phenanthrene comprised between 14.2% and 33.1% over a period of 62 days of incubation in the dark at 14°C, in order to approximate field conditions. This study used a BACTRAP® system (composed of activated carbon pellets) that allowed trapping a bacterial community already present in the aquifer by the system for 100 days. In this experiment, the percentage of dissolved oxygen was always recorded to ensure a minimum of 1% content in order to maintain an oxic condition representative of thein-situconditions. The use of an adapted bacterial community may lead to an overestimation of the mineralisation rate in comparison to the situation arising in other aquifer. This study highlighted that phenanthrene degradation was slow in oxic aquifer, indicating possible persistence. Biodegradation was observed in the presence of an adapted bacterial community (100 days of incubation plus 62 days of exposure to reach 33% of mineralisation).

An extended summary of a water-sediment simulation OECD 308 study was provided during the public consultation focusing on phenanthrene (Meisterjahn et al. 2018a). The tests were conducted in closed biometer systems due to significant observed loss of test material in flow-through setups during pre-tests. All other parameters were followed as expressed in the guideline. The reported half-lives for the total system estimated by CAKE calculation ranged between 114 to 150 days depending on the considered sediment and statistical assessment (one sediment had fine texture and high organic carbon content; the other had a coarse texture and low organic carbon content). The DegT50 for the first sediment range from 114 to 130 days and from 116 to 150 days for the second sediment. These data are below the cut-off value for P criteria. Nevertheless, the ModelMaker calculation for compartment specific (Water and sediment phase) provide half-lives (DT50) for the first sediment of 56 days for water and 305 days for sediment. For the second sediment, the ModelMaker calculation provides DT50 of 172 days for water and 116 days for sediment. These model calculations indicate, at the opposite of the other DegT50 determine by the CAKE calculation, that the phenanthrene is vP for sediment. Moreover, the experiments were performed at 20°C. However, for a regulatory purpose, the recommended temperature is 12°C, as recommended in the R7-Guidance on information requirements and chemical safety assessment. When recalculations were done with the simplified Arrhenius equation recommended by ECHA, the DegT50 were all above the cut-off value of 180 days, comprised between 216 to 247 days for the first sediment and comprised between 220 to 285 days for the second sediment. If the methodology used the non-simplified Arrhenius equation, the DegT50 were between 242 to 276 days for the first sediment and between 246 to 319 days for the second sediment. Thus, data indicate that a low biodegradation of phenanthrene is observed in sediments, based on which phenanthrene meets the vP criteria for sediment.

 

[…]

 

Summary and discussion on biodegradation

Regarding water and sediment, Mackay etal.(1992) indicated that predicted phenanthrene elimination half-lives ranged between 13 and 42 days and that the substance persisted in sediment with half-lives between 420 to 1250 days. Regarding the available information from the ready biodegradation tests showing not ready biodegradation for one result (Junker et al., 2016), and ready biodegradation from the other (INERIS, 2010), biodegradation of phenanthrene may occur in water. An extended summary of a water-sediment simulation OECD 308 study was provided during the public consultation (Meisterjahn et al., 2018a). The DegT50 for the first sediment ranged from 114 to 130 days and from 116 to 150 days for the second sediment. These data are below the cut-off value for P criteria. When recalculations were done at 12°C DegT50 were all above the cut-off value of 180 days, comprised between 216 to 319 days. Thus, data indicate that a low biodegradation of phenanthrene is observed in sediments, based on which phenanthrene meets the vP criteria for sediment.

[…].

 

Summary and discussion on degradation

[…]

The predicted half-lives range between 13 to 42 days for degradation in water and between 420 to 1250 days for sediment. In the sediment compartment, a low biodegradation of phenanthrene is observed. The low degradation rate is confirmed in a sediment simulation study according to OECD TG 308, provided during the public consultation (Meisterjahn et al. 2018a), based on which phenanthrene meets the vP criteria for sediment. […]

End of excerpt

 

References

ECHA. 2009. “Support Document for identification of Coal Tar Pitch, High Temperature as a SVHC because of its PBT and CMR properties.” http://echa.europa.eu/documents/10162/73d246d4-8c2a-4150-b656-c15948bf0e77

The Netherlands. 2008. Annex XV Transitional Dossier for substance Coal Tar Pitch, High Temperature, CAS Number: 65996-93-2.URL: https://echa.europa.eu/documents/10162/ef47ccc5-0786-4bf5-b16c-2f13c6c49385

Bahr, A., A. Fischer, C. Vogt, and P. Bombach.2015. "Evidence of polycyclic aromatic hydrocarbon biodegradation in a contaminated aquifer by combined application of in situ and laboratory microcosms using 13C-labelled target compounds." Water Research 69:100-109. doi: 10.1016/j.watres.2014.10.045.

CITI-Japan, 1992, Biodegradation and bioaccumulation data of existing chemicals based on CSCL Japan. Chemicals Inspection and Testing Institute

De Maagd PG-J. 1996. “Polycyclic aromatic hydrocarbons: fate and effects in aquatic environment.”Utrecht, Utrecht University.

Durant, N. D., L. P. Wilson, and E. J. Bouwer.1995. "Microcosm studies of subsurface PAH-degrading bacteria from a former manufactured gas plant." Journal of Contaminant Hydrology 17 (3):213-237. doi: https://doi.org/10.1016/0169-7722(94)00034-F.

INERIS .2010.“Fiche de données toxicologiques et environnementales des substances chimiques – PHENANTHRENE.”

Junker T., A. Coors, G.Schüürmann, 2016. "Development and application of screening tools for biodegradation in water–sediment systems and soil." Science of The Total Environment 544, 1020-1030.

Mackay, D., W. Y. Shiu, and K. C. Ma. 1992. "Illustrated handbook of physical-chemical properties and environmental fate for organic chemicals. Volume II: polynuclear aromatic hydrocarbons, polychlorinated dioxins, and dibenzofurans." Lewis Publishers, Boca Raton, FL. 1992. 597.

Meisterjahn et al., 2018b (Report in preparation). Degradation of 14C labelled hydrocarbons in Water-Sediment using standard and optimized OECD test guidelines - 308. Germany: Fraunhofer IME-AE.

Neff, J.M. 1979. “Polycyclic aromatic hydrocarbons in the aquatic environment. Sources, fate and biological effects.” Applied Science Publishers, London, 262 pp.

Volkering F., and Breure A.M. 2003. “Biodegradation and general aspects of bioavailability.“ In Douben (ed.) PAHs: An Ecotoxicological Perspective., Wiley, 81- 98.

 

Data indicate that phenanthrene can be biodegraded in water even though it may not be readily biodegradable. Thus it is not clear whether P or vP criteria of REACH, Annex XIII are met or not. In a water-sediment simulation study according to OECD TG 308 carried out at 20 °C, half-lives in sediment were determined to range from 114 to 150 days thus spreading around the P criterion (120 d) of REACH, Annex XIII. When recalculated to a temperature of 12 °C, which is the recommended temperature for regulatory purposes according to guidance documents, the diss. half-lives were determined to fall in the range from 216 to 319 days now clearly exceeding the vP criterion of REACH, Annex XIII.

Validity criteria fulfilled:
not applicable
Conclusions:
Information on the biodegradation of phenanthrene in water is inconsistent. In tests according to OECD TG 301C (MITI I test), biodegradation was observed, but the criterion for ready biodegradation was not met in one test but was met in a second one. The biodegradation potential of phenanthrene in water was estimated by model calculations resulting in half-lives in the range of 12.5 to 42 days.
In a study according to OECD TG 308 (Transformation in aquatic sediment systems), half-lives between 216 and 319 days were determined after recalculation of the experimental results (20 °C) to a temperature of 12 °C. The vP criterion of REACH, Annex XIII is thus exceeded.
Endpoint:
biodegradation in water and sediment: simulation testing, other
Remarks:
simulation testing in water and sediment
Type of information:
other: related information taken from the ECHA SVHC support document for anthracene, a major constituent of anthracene oil
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Remarks:
information taken from the ECHA SVHC support document for anthracene, a major constituent of anthracene oil
Principles of method if other than guideline:
The SVHC support document reviews and reports data relevant for the assessment of biodegradation of anthracene, a major constituent of anthracene oil.
Specific details on test material used for the study:
Substance is specified by EC and CAS number. Data reported relate to this substance.
Oxygen conditions:
other: various
Inoculum or test system:
other: various
Key result
Compartment:
water
DT50:
ca. 12.5 - ca. 42 d
Temp.:
20 °C
Remarks on result:
other: estimate based on model calculations by Mackay (1992)
Key result
Compartment:
sediment
DT50:
ca. 125 - ca. 420 d
Temp.:
20 °C
Remarks on result:
other: estimate based on model calculations by Mackay (1992)
Transformation products:
not specified

Excerpt from SVHC support document

 

Biodegradation

 

Screening tests

Mackay et al. (1992) allocated anthracene to persistency class 4 for water and class 7 for sediment corresponding to half-lives of 13-42 days (water) and 420-1250 days (sediment). These half-lives are used in the risk assessments of anthracene and coal tar pitch, high temperature (European Commission, 2007a, 2007b). Lower half-lives have been reported in the literature with respect to the disappearance of anthracene from the culture medium (either by volatilisation, adsorption, biotransformation or uptake by organisms). However, it needs to be stressed that these studies only consider dissipation and not mere degradation of anthracene (e.g. mineralisation).

Degradation of 1.9 % of the initial anthracene concentration measured as BOD was observed in a 14 day ready biodegradability test (MITI I, OECD 301C) using 100 mg/l anthracene and 30 mg/l sludge (CITI, 1992). Sludge employed in the test was likely to be predominantly domestic. According to the MITI test, which is suitable for substances with low water solubility, anthracene is not readily biodegradable.

Significant degradation due to gradual adaptation was reported for anthracene in a biodegradation test by Tabak et al. (1981). A static screening procedure based on BOD monitoring was used. The inoculum used was settled domestic sewage sludge. The cultures were incubated for seven days in the dark at 25 ºC. A subculture of the inoculum was taken after 7 days and incubated for a further 7 days. A total of three subcultures were taken, i.e. at the end of the incubation period of the third subculture the inoculum had been adapted for 28 days. Test concentrations of 5 and 10 mg/l were introduced into the flasks using dispersant. Degradation in the range of 26 % (at day 7) up to 92 % (at day 28) resulted. This study demonstrates that waste water treatment plant microorganisms can adapt to biodegrade anthracene but the rate of biodegradation cannot be judged on the basis of the study.

 

 

Simulation tests

The degradation of PAHs in sediment was studied byGardner et al. (1979). Sediment has been spiked with crude oil enriched with selected PAHs. Three different sediment types were used: fine sand (0.125 to 0.25 mm particle size), medium sand (0.25 to 0.5 mm) and marsh sediment (61 % sand (0.062 to 2 mm) 12 % silt (0.002 to 0.062 mm), and 26 % clay (< 0.002 mm particle size). Each tray (0.1 m²) contained 2 l dry volume of sediment. The incubation temperature was 20 ± 2°C. Estuarine water (salinity 25 ‰) and 5 ml of the crude oil enriched with 0.1 g of e.g. anthracene was added to each tray. The experiment lasted for 31 weeks.

The initial concentrations of anthracene were highest in the marsh sediment (40 μg/g dry sediment) and lowest in the medium sand (10.3 μg/g dry sediment). The authors reported that between 2.0 % (fine sand) and 3.2 % (medium sediment) of anthracene was removed every week. In general, PAH degradation was higher in surface than in subsurface layers of sediment. The authors concluded that slow removal of PAHs from marsh sediments may have been caused by factors making the oils unavailable to microorganisms (e.g. adsorption to clay minerals or sediment organic material).

The study provided by Gardner et al (1979) simulates an oil spill to a water body and is valid with restrictions since no mass balance is available and possible effects of adsorption or volatilisation of the PAHs have not been considered. Although no half-lives have been calculated, the results indicate that anthracene is persistent in lower sediment layers.

Lee & Ryan (1983)studied biodegradation of 14C-labelled anthracene in water and sediment measuring the evolution of 14CO2 and degradation products. Water and sediment were collected for the study from one heavily with oil contaminated estuary in Charleston, SC, and from a “cleaner” estuary in Savannah, GA, in the United States. The sediment samples were taken from the upper 1 cm where microbial degradation of hydrocarbon is highest.

For the biodegradation test in water, 14C-labelled anthracene was added to 100 ml samples in 250 ml flasks in a concentration of 25 μg/l. For the test in sediment, 14C-labelled anthracene was added to a sediment-seawater slurry consisting of 1 g of sediment and 50 ml of seawater in 125 ml bottles. Test concentration was 2.5 mg/kg (no information whether dwt or wwt). Triplicate samples were tested. Incubation temperature was 27 ºC for the samples from Charleston and 28 °C for the samples from Savannah. With regard to the biodegradation test in water, the authors observed little, if any, degradation of anthracene, whereas for the sediment test mineralisation half-lives of 210 days (the “cleaner” Savannah sediment) and 57 days (the contaminated Charleston sediment) were extrapolated (Lee & Ryan 1983).

A similar test was performed with sediment samples from Narragansett Bay, RI, which were incubated in mesocosms(Lee & Ryan 1983). The study resulted in dissipation half-lives of 95, 99, and 141 days for test concentrations of 1, 2.5 and 5.0 mg anthracene/kg, respectively at temperatures of 18 °C. Those mesocosm sediments which were pre-adapted by fuel oil addition, showed degradation half-lives of 5, 6, and 7 days, respectively, at concentrations of 1, 2.5 and 5.0 mg/kg. According to the authors, biodegradation was at negligible or low level in mesocosm water samples.

It must be noted that the test conditions of Lee & Ryan (1983) did not resemble conditions required at the present for simulation tests. The batch size was small and the water-sediment batches were agitated. Moreover the sediment samples were taken from the upper sediment layer, where degradation is higher than in lower layers. Hence, the test system produced enhanced biodegradation rates compared to environmentally relevant conditions. In addition, the degree of pre-adaptation of the samples cannot be judged, because the characteristics of the sites were not reported in detail.

Bauer et al. (1985)conducted a trial sequence for testing the impact of temperature, oxygen, NO3, glucose and pre-adaptation on the biodegradation of anthracene. The tests were conducted using sediment-water slurries (1:2 wwt/vol) with aerobic and anaerobic sediment and seawater (28 ‰) sampled from the intertidal Flax Bond Saltmarsh (NY). A slurry volume of 2.5 to 10 ml was employed in the tests and all slurry incubations were conducted in 20 ml vials in the dark under continuous shaking. Test and pre-adaptation concentrations of 1 to 1000 ppm (1 to 1000 μg per g dwt sediment) were used and incubation times were between 7 and 28 days, depending on the test. The biodegradation of the parent compound was measured with non-adapted microorganisms under aerobic and anaerobic conditions at 25 °C and a concentration of 100 μg/g sediment. Ultimate biodegradation was observed in the aerobic vials. The amount of evolved 14CO2 was 11 % (28 days) calculated on the basis of the initial concentration. Primary degradation of anthracene reached 99 % of the initial amount. 14CO2-evolution lagged 18 to 20 days, but anthracene disappearance did not show any lag. It must be noted, that the pool of anthracene in the extraction residues was not measured and thus it is not possible to estimate the quantity of total primary degradation. The authors observed a complete lack of degradation in anaerobic conditions but degradation started immediately after oxygen addition, indicating that facultative microbial degraders were present.

Among the environmental factors studied by Bauer et al. (1985), mineralisation was concluded to be mainly influenced by oxygen concentration and temperature. The test on temperature dependency showed a doubling at 20 ºC and tripling at 30 ºC of the mineralisation rate compared to the lowest test temperature of 10 ºC. In all trial variations, slurries pre-adapted to 100 μg anthracene/g sediment were also tested and resulted in faster rates of mineralisation and anthracene disappearance. A maximum of 47 % mineralisation was observed in a trial with 14 days preadaptation of the inoculum to 100 μg anthracene/g sediment. It must be noted, that in the study of Bauer et al. (1985) the very small size of the batches, the large relation of sediment:water volumes and shaking are assumed to have enhanced the biodegradation in comparison to environmental conditions. In addition, the quality of seawater and sediment samples was not described.

In line with the results of Bauer et al. (1985), PAHs in general are considered to be persistent under anaerobic conditions (e.g., Neff, 1979; Leduce et al., 1992) with the consequence that they persist in anaerobic sediment, which normally means in the bulk of sediment, except of the top few aerobic millimetres.

[…]

Marine cyanobacteriaOscillatoria salinaBiswas,Plectonnema terebransBornet et Flahault, andAphanocapsaspecies degraded Bombay High crude oil in flasks containing seawater with a salinity of 25‰ and pH of 5.7-8.2. The cultures were incubated under 12h:12h light and dark cycle at 28 °C. Light was provided by two fluorescent lamps of 40 W placed at distance of approximately 40 cm. After 10 days 90.6 % of anthracene contained in the crude oil added was degraded byOscillatoria salina, 62.7 % byPlectonnema terebransand 41.9 % byAphanocapsa species(Raghukumar et al., 2001). In addition, methanogenic bacteria retrieved from marine sediment by Rockne et al. (1998) andRhodococcusspecies, sampled from polluted river sediment by Dean-Ross et al. (2001), have been observed to degrade anthracene. These studies are considered as evidence that anthracene can be biodegraded by certain organisms but the rate of biodegradation at environmentally relevant conditions cannot be determined on the basis of this information.

 

[…]

 

Summary and discussion of persistence

Based on the reviewed information it can be concluded that in general degradation of anthracene is limited by its low water solubility and its strong tendency to adsorb to particles and organic matter.

Once released to aqueous systems, anthracene is expected to partition to sediment due to its tendency to adsorb to particles and organic matter. To some extent anthracene might also volatilise and be degraded in air by photo-oxidative processes. Some studies indicate that anthracene might be degraded in water by highly adapted micro-organisms under aerobic conditions. However, most of the available studies on biodegradation resulted in negligible or slow mineralisation rates.

In sediment mineralisation half-lives of up to 210 days were determined by Lee & Ryan (1983) showing that anthracene fulfils both the P-criterion and the vP-criterion in sediment. […]

End of excerpt

 

References

European Commission, 2007a. European Risk Assessment Report, Draft of November 2007, Anthracene, CAS No: 120-12-7, EINECS No: 204-371-1. UWRL:

https://echa.europa.eu/documents/10162/08a49c89-9171-4cb2-8366-108601ac565c(final approved version of April 2008

European Commission, 2007b. European Union Risk Assessment Report, Draft of November 2007, Coal tar pitch, high temperature, CAS No: 65996-93-2, EINECS No: 266-028-2. URL:https://echa.europa.eu/documents/10162/433ccfe1-f9a5-4420-9dae-bb316f898fe1(final draft version of April 2008)

Bauer, J. and Capone, D., 1985. Degradation and mineralization of the polycyclic aromatic hydrocarbons anthracene and naphthalene in intertidal marine sediments. Appl. Environ. Microbiol., 50, 81-90.

CITI 1992. Japan chemical industry. Biodegradation and bioaccumulation data of existing chemicals based on the CSCL Japan, compiled under the supervision of chemical Products Safety division, Basic Industries Bureau MITI, ed. by CITI, October 1992. Published by Japan Chemical Industry Ecology and Information Center.

Dean-Ross, D., Moody, J. D., Freeman, J. P., Doerge, D. R., Cerniglia, C. E.A., 2001. Metabolism of anthracene by a Rhodococcus species. FEMS Microbiol. Lett., 204, 205-211.

Gardner, W. S., Lee, R. F., Tenore, R. K., Smith, L. W., 1979. Degradation of selected polycyclic hydrocarbons in coastal sediments: importance of microbes and polychaete worms. Water Air Soil Pollut., 11, 339-347.

Leduce, R., Samson, R., Al-Bashir, B., Al-Hawari, J., Cseh, T., 1992. Biotic and abiotic disappearance of four compounds from flooded soil under various redox conditions. Wat. Sci. Tech., 26, 5-60.

Lee, R. F., Ryan, C., 1983. Microbial and photochemical degradation of polycyclic aromatic hydrocarbons in estuarine waters and sediments. Can. J. Fish. Aquat. Sci., 40, 86-94.

Mackay D, Shiu WY, Ma K. 1992. Illustrated handbook of physical-chemical properties and environmental fate for organic chemicals. Vol. II: Polynuclear aromatic hydrocarbons, polychlorinated dioxins and dibenzofurans. Lewis Publishers, Chelsea.

Neff, J. M., 1979. Polycyclic aromatic hydrocarbons in the aquatic environment. Sources, fates and biological effects (Neff, J.M., ed.), Applied Science Publishers Ltd., London.

Raghukumar, C., Vipparty, V., David, J. J., Chandramohan, D., 2001. Degradation of crude oil by marine cyanobacteria. Appl. Microbiol. Biotechnol., 57, 433-436.

Rockne, K. J., Stensel, H. D., Herwig, R. P., Strand, S. E., 1998.PAH degradation and bioaugmentation by a marine methanotrophic enrichment. Bioremediat. J., 1, 209-222.

Tabak, H. H., Quave, S. A., Mashni, C. I.; Barth, E. F., 1981. Biodegradability studies with organic priority pollutant compounds. J. Water Pollut. Control Fed., 53, 1503-18.

 

Data indicate that anthracene can be biodegraded in water at least to some extent (compare Tabak et al 1981, first 7 days). This is the case especially after adaptation of the microbial inoculum. From existing data it is not clear whether P or vP criteria of REACH, Annex XIII are met or not. But generally, biodegradation of anthracene in water is estimated to be low.

In sediment biodegradation tests not following guidelines, varying degradation rates of anthracene were observed. Half-lives ranged from over 200 to only a few days with short half-lives especially in upper layer sediments and in contaminated sediments (pre-adapted to PAH). Due to variable not standardised conditions, a reliable half-life for regulatory purposes cannot be concluded from these studies.

In a water-sediment simulation study with phenanthrene according to OECD TG 308, half-lives between 216 and 319 days were determined after recalculation of experimental results (20 °C) to a temperature of 12 °C, which is the recommended temperature for regulatory purposes. Due to the similar structure of anthracene and phenanthrene it can be assumed that biodegradation properties in sediment will be similar. Based on the lower water solubility and higher log Kow of anthracene it can be concluded that biodegradation of anthracene in sediment is very likely to be slower than biodegradation of phenanthrene. Consequently, the vP criterion of REACH regulation, Annex XIII for sediment will be exceeded.

Anthracene was allocated to persistence classes on the basis of model calculations (Mackay et al., 1992). Corresponding half-lives are 12.5 - 42 days for water and 420 - 1250 days for sediment. As no experimental data are available, these values are used in characterising the biodegradation of anthracene in water and sediment, respectively.

Validity criteria fulfilled:
not applicable
Conclusions:
Taking into account information on biodegradation of other PAH in water, soil, and sediment, it can be concluded that fluoranthene biodegrades slowly in the environment with half-lives very likely in the range of the P criterion of REACH, Annex XIII for water and definitly above the vP criterion for sediment.
Endpoint:
biodegradation in water and sediment: simulation testing, other
Remarks:
simulation testing in water and sediment
Type of information:
other: related information taken from the ECHA SVHC support document for fluoranthene, a major constituent of anthracene oil
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Remarks:
information taken from the ECHA SVHC support document for fluoranthene, a major constituent of anthracene oil
Principles of method if other than guideline:
The SVHC support document reviews and reports data relevant for the assessment of biodegradation of fluoranthene, a major constituent of anthacene oil.
Specific details on test material used for the study:
Substance is specified by EC and CAS number. Data reported relate to this substance.
Oxygen conditions:
other: various
Inoculum or test system:
other: various
Key result
Compartment:
water
DT50:
ca. 13 - ca. 42 d
Temp.:
20 °C
Remarks on result:
other: estimate based on model calculations by Mackay (1992)
Key result
Compartment:
sediment
DT50:
> 1 250 d
Temp.:
20 °C
Remarks on result:
other: estimate based on model calculations by Mackay (1992)
Transformation products:
not specified

Excerpt from SVHC support document

 

Biodegradation

 

Estimated data

As indicated in the Annex XV transitional dossier for CTPHT (The Netherlands, 2008), Mackay et al. (1992) ranked 16 PAH according to their persistence in water, soil and sediment in different classes which correspond to a specific half-live in these compartments. The calculated half-lives of fluoranthene in water are in the range of 300-1000 h and for sediment longer than 1250 days.

 

Biodegradation in water and sediment

The biodegradation in water was already assessed in the Support Document for identification of CTPHT as SVHC (ECHA, 2009):

Standard tests for biodegradation in water have demonstrated that PAHs with up to four aromatic rings are biodegradable under aerobic conditions, but that biodegradation rates of PAHs with more aromatic rings are very low (The Netherlands, 2008). In general, the biodegradation rates decrease with increasing number of aromatic rings. This correlation has been attributed to factors like the bacterial uptake rate and the bioavailability. The bacterial uptake rate has been shown to be lower for the higher molecular weight PAHs as compared to the PAHs of lower molecular weight. This may be due to the size of high molecular weight members, which limits their ability to cross cellular membranes. In addition, bioavailability is lower for higher molecular PAHs due to adsorption to organic matter in water and sediment. It has further been shown that half-lives of PAHs in estuarine sediment are proportionally related to the octanol-water partition coefficient (Kow) (Durant et al., (1995) cited in The Netherlands, 2008).

In general, PAHs are considered to be persistent under anaerobic conditions (Neff (1979); Volkering and Breure (2003) cited in The Netherlands, 2008). Aquatic sediments are often anaerobic with the exception of a few millimetre thick surface layer at the sediment-water interface, which may be dominated by aerobic conditions. The degradation of PAHs in aquatic sediments is therefore expected to be very slow.

Mackayet al. (1992) predicted that fluoranthene persists in sediment with half-lives higher than 1250 days. For water degradation, Mackayet al. (1992) predicted elimination half-lives between 300 and 1000 hours. Fluoranthene consists of 4 aromatic rings, so standard tests for biodegradation in water may reveal that fluoranthene is biodegradable under aerobic conditions (European Commission, 2008).

Smith et al. (2012) studied biodegradation kinetics of phenanthrene and fluoranthene by the bacterium Sphingomonas paucimobilis EPA505 using a dynamic passive dosing technique. Similar mineralization fluxes were observed for both substances, which increased by two orders of magnitude with increasing dissolved concentrations.

[…]

At present fluoranthene has not been tested in a sediment simulation study (OECD 308). However, during the public consultation a summary of such a study was provided in which the degradation of phenanthrene was studied (Meisterjahn et al. 2018). When converted to 12°C, the half-lives observed were higher than the vP criterion. Considering that the biodegradation rates decrease with increasing number of aromatic rings and the half-lives of PAHs in estuarine sediment are proportionally related to the octanol-water partition coefficient (Kow) (Durant et al. (1995) cited in the Annex XV transitional dossier for CTPHT (The Netherlands, 2008)), it can be assumed that fluoranthene also meets the P and vP criterion in sediment.

 

[…]

 

Summary and discussion on biodegradation

For water degradation, Mackay et al. (1992) predicted half-lives between 300-1000h.

It is assumed that fluoranthene meets the P and vP criterion in sediment, as in the available simulation study with phenanthrene the half-life meets the P and vP criterion. Considering that the biodegradation rates decrease with increasing number of aromatic rings and the half-lives of PAHs in sediment are proportionally related to the octanol-water partition coefficient (Kow), the half life of fluoranthene should meet the P and vP criteria in sediment as well.

The half-live predicted by Mackayet al.(1992) supports the persistency of fluoranthene in sediments (half-life > 1250 days).

[…]

[…] Data indicate that a low biodegradation of fluoranthene is observed in sediments, based on which fluoranthene meets the vP criteria for sediment.

Therefore, it is concluded that based on the available data, fluoranthene biodegrades very slowly in soil and sediment.

 

Summary and discussion on degradation

[…]

Estimated half-lives range between 300 and 1000 hours for water degradation and half-lives higher than 1250 days for sediment.

In view of the fact that phenanthrene meets the P and vP criterion in a sediment simulation study (Meisterjahn et al., 2018), it is assumed that fluoranthene will meet the P and vP criterion as well, considering that the biodegradation rates decrease with increasing number of aromatic rings and the half-lives of PAHs in sediment are proportionally related to the octanol-water partition coefficient (Kow) (Durant et al. (1995), cited in the Annex XV transitional dossier for CTPHT (The Netherlands, 2008)).

[…]

Based on the sediment study of phenanthrene and field and microcosm studies in soil of fluoranthene, it is concluded that fluoranthene meets the P and vP criteria for soil and sediment.

The available information allows to conclude that fluoranthene meets the P and vP criteria for sediments and soil.

End of excerpt

 

References

ECHA (2009): Support Document for identification of Coal Tar Pitch, High Temperature as a SVHC because of its PBT and CMR properties. URL: http://echa.europa.eu/documents/10162/73d246d4-8c2a-4150-b656-c15948bf0e77

European Commission (2008): European Union Risk Assessment Report, Coal Tar Pitch High Temperature, CAS No: 65996-93-2, EINECS No: 266-028-2. URL:https://echa.europa.eu/documents/10162/433ccfe1-f9a5-4420-9dae-bb316f898fe1

The Netherlands (2008): Annex XV Transitional Dossier for substance Coal Tar Pitch, High Temperature, CAS Number: 65996-93-2. URL: http://echa.europa.eu/documents/10162/73d246d4-8c2a-4150-b656-c15948bf0e77

Durant, ND, Wilson, LP, and Bouwer, EJ (1995) Microcosm studies of sunsurface PAH-degrading bacteria from a former manufactured gas plant. J Contam. Hydrol., 17, 213-223

Mackay D., Shiu W.Y. and Ma K.C. (1992): Illustrated handbook of physical-chemical properties and environmental fate of organic chemicals. Lewis Publishers, Boca Raton, FL, USA.

Meisterjahn et al. (2018) (Report in preparation). Degradation of 14C labelled hydrocarbons in Water-Sediment using standard and optimized OECD test guidelines - 308. Germany: Fraunhofer IME-AE

Neff, JM (1979) Polycyclic aromatic hydrocarbons in the aquatic environment. Sources, fate and biological effects. Applied Science Publishers, London

Smith K.E.C., Rein A., Trapp S., Mayer P., Karlson U.G. (2012) Dynamic passive dosing for studying the biotransformation of hydrophobic organic chemicals: Microbial degradation as an example. Environmental Science and Technology, 46, 4852-4860

Volkering F, Breure AM (2003) Biodegrdation and general aspects of bioavailability. In Douben (ed.) PAHs: An Ecotoxicological Perspective., Wiley, 81- 98

Overall, it can be concluded that microorganisms are present in the environment that can degrade fluoranthene under aerobic conditions. But based on the structure of fluoranthene (four-ring PAH) and its log Kow value, degradation rates will already be slow in water and even slower in sediment. In soil, maximum dissipation half-lives of 184 and 377 days at a temperature of 20 °C or slightly higher have been determined (Wild and Jones 1993 and Park et al. 1990, respectively). It can be assumed that biodegradation in sediment will be slower than biodegradation in soil. In addition, biodegradation of fluoranthene in sediment is assessed to be slower than biodegradation of phenanthrene based on the structure and log Kow of both substances. Consequently, the half-life of fluoranthene is estimated to be longer than the half-life of phenanthrene obtained in a simulation study (216 to 319 days at 12 °C). The vP criterion of REACH, Annex XIII will be exceeded for fluoranthene.

Fluoranthene was allocated to persistence classes on the basis of model calculations (Mackay et al., 1992). Corresponding half-lives are 12.5 - 42 days for water and > 1250 days for sediment. As no experimental data are available, these values are used in characterising the biodegradation of fluoranthene in water and sediment, respectively.

Validity criteria fulfilled:
not applicable
Conclusions:
Taking into account information on biodegradation of other PAH in water, soil, and sediment, it can be concluded that fluoranthene biodegrades slowly in the environment with half-lives very likely in the range of the P criterion of REACH, Annex XIII for water and definitly above the vP criterion for sediment.
Endpoint:
biodegradation in water and sediment: simulation testing, other
Remarks:
simulation testing in water and sediment
Type of information:
other: related information taken from the ECHA SVHC support document for pyrene, a relevant constituent of anthracene oil
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Remarks:
information taken from the ECHA SVHC support document for pyrene, a relevant constituent of anthracene oil
Principles of method if other than guideline:
The SVHC support document reviews and reports data relevant for the assessment of biodegradation of pyene, a relevant constituent of anthacene oil especially with regard to biodegradation.
Specific details on test material used for the study:
Substance is specified by EC and CAS number. Data reported relate to this substance.
Oxygen conditions:
other: various
Inoculum or test system:
other: various
Key result
Compartment:
water
DT50:
ca. 42 - ca. 125 d
Temp.:
20 °C
Remarks on result:
other: estimate based on model calculations by Mackay (1992)
Key result
Compartment:
sediment
DT50:
> 1 250 d
Temp.:
20 °C
Remarks on result:
other: estimate based on model calculations by Mackay (1992)
Transformation products:
not specified

Excerpt from SVHC support document

 

Biodegradation

 

Biodegradation in water and sediments

The biodegradation in water was already assessed in the Annex XV Transitional Dossier for CTPHT (The Netherlands, 2008) and summarised in the Support Document for identification of CTPHT as SVHC (ECHA, 2009), thus this section will not be assessed again within this dossier.

Experimental information for biodegradation in water has demonstrated that PAH substances with up to four aromatic rings are biodegradable under aerobic conditions, but that biodegradation rates of PAHs with more than four aromatic rings, are very low (The Netherlands, 2008).

In general, the biodegradation rates decrease with increasing number of aromatic rings. This correlation has been attributed to factors like the bacterial uptake rate and the bioavailability. The bacterial uptake rate has been shown to be lower for the higher molecular weight PAHs as compared to the PAHs of lower molecular weight. This may be due to the size of high molecular weight members, which limits their ability to cross cellular membranes. In addition, bioavailability is lower for higher molecular PAHs due to adsorption to organic matter in water and sediment. It has further been shown that half-lives of PAHs in estuarine sediment are proportionally related to the octanol-water partition coefficient (Kow) (Durant et al. (1995) cited in the Annex XV Transitional Dossier for CTPHT (The Netherlands, 2008)).

Mackay et al. (1992) estimated half-lives in the different environmental compartments based on model calculations and literature research. The calculated half-lives of pyrene in water were in the range of 42 to 125 days, and were estimated to be longer than 1250 days for the sediment compartment (ECHA, 2009).

[…]

At present pyrene has not been tested in a sediment simulation study (OECD 308). However, during the public consultation a summary of such a study was provided in which the degradation of phenanthrene was studied (Meisterjahn et al. 2018). When converted to 12°C, the half-lives observed were higher than the vP criterion. Considering that the biodegradation rates decrease with increasing number of aromatic rings and the half-lives of PAHs in estuarine sediment are proportionally related to the octanol-water partition coefficient (Kow) (Durant et al. (1995) cited in the Annex XV Transitional Dossier for CTPHT (The Netherlands, 2008)), it can be assumed that pyrene also meets the P and vP criterion in sediment.

 

[…]

 

Summary and discussion on biodegradation

For water, Mackay et al. (1992) predicted long half- lives in the range of 42 to 125 days. It is assumed that pyrene meets the P and vP criterion in sediment, as in the available simulation study with phenanthrene the half life meets the P and vP criterion. Considering that the biodegradation rates decrease with increasing number of aromatic rings and the half-lives of PAHs in sediment are proportionally related to the octanol-water partition coefficient (Kow), the half life of pyrene should meet de P and vP in sediment as well. The half-life predicted by Mackay et al. (1992) support the persistency of pyrene in the sediments (half-life> 1250 days).

[…]

It is concluded that, based on the available data, pyrene degrades very slowly in sediments and soils.

 

Summary and discussion of degradation

[…]

Estimated half-lives for pyrene in water ranged between 42 - 125 days and for sediments longer than 1250 days. In view of the fact that phenanthrene meets the P and vP criterion in a sediment simulation study (Meisterjahn et al. 2018), it is assumed that pyrene will meet P and vP criterion as well considering that the biodegradation rates decrease with increasing number of aromatic rings and the half-lives of PAHs in sediment are proportionally related to the octanol-water partition coefficient (Kow) (Durant et al. (1995) cited in The Netherlands, 2008).

[…]

The available information allow to conclude that pyrene meets the P and vP criteria for sediments and soil.

End of excerpt

 

References

 

ECHA (2009): Support Document for identification of Coal Tar Pitch, High Temperature as a SVHC because of its PBT and CMR properties.http://echa.europa.eu/documents/10162/73d246d4-8c2a-4150-b656-c15948bf0e77

The Netherlands (2008): Annex XV Transitional Dossier for substance Coal Tar Pitch, High Temperature, CAS Number: 65996-93-2.https://echa.europa.eu/documents/10162/13630/trd_netherlands_pitch_en.pdf/a8891f7e-59c8-4d67-97f7-93bb9a9e2676

Durant ND, Wilson LP, Bouwer EJ (1995): Microcosm studies of subsurface PAH-degrading bacteria from a former manufactured gas plant. J Contam Hydrol 17, 213-223

Mackay D., Shiu W.Y. and Ma K.C. (1992): Illustrated handbook of physical-chemical properties and environmental fate of organic chemicals. Lewis Publishers, Boca Raton, FL, USA

Meisterjahn et al. (2018) (Report in preparation). Degradation of 14C labelled hydrocarbons in Water-Sediment using standard and optimized OECD test guidelines - 308. Germany: Fraunhofer IME-AE

Overall, it can be concluded that microorganisms present in the environment can degrade pyrene under aerobic conditions especially after adaptation to PAH. But based on the structure of pyrene (four-ring PAH) and its log Kow value, degradation rates will already be slow in water and even slower in sediment. In soil, maximum dissipation half-lives of 320 and 260 days at a temperature of 20 °C or slightly higher have been determined (Wild and Jones 1993 and Park et al. 1990, respectively). It can be assumed that biodegradation in sediment will be slower than biodegradation in soil. In addition, biodegradation of pyrene in sediment is assessed to be slower than biodegradation of phenanthrene based on the structure and log Kow of both substances. Consequently, the half-life of pyrene is estimated to be longer than the half-life of phenanthrene obtained in a simulation study (216 to 319 days at 12 °C). The vP criterion of REACH, Annex XIII will be exceeded for pyrene.

Pyrene was allocated to persistence classes on the basis of model calculations (Mackay et al., 1992). Corresponding half-lives are 42 - 125 days for water and > 1250 days for sediment. As no experimental data are available, these values are used in characterising the biodegradation of pyrene in water and sediment, respectively.

Validity criteria fulfilled:
not applicable
Conclusions:
Taking into account information on the biodegradation of other PAH in water, soil, and sediment, it can be concluded that pyrene biodegrades slowly in the environment with half-lives above the vP criterion of REACH, Annex XIII very likely in water and definitely in sediment.

Description of key information

Anthracene oil (< 50 ppm BaP) [CAS no. 90640 -80 -5] is a UVCB substance consisting of a complex combination of polycyclic aromatic hydrocarbons. Simulation tests on the biodegradation of the substance in surface water and in sediment have not been located. Instead information obtained for selected constituents of anthracene oil is used in order to characterise the biodegradation of the substance in water and sediment.

For several constituents of anthracene oil, information on their biodegradation properties is available. This data is summarised in SVHC support documents of these substances prepared by ECHA (Member State Committee). This information in combination will be used to specify the biodegradation of anthracene oil in water and sediment.

Key value for chemical safety assessment

Half-life in freshwater:
125 d
at the temperature of:
20 °C
Half-life in freshwater sediment:
1 250 d

Additional information

Anthracene oil is a UVCB substance and comprises mainly 3-ring aromatic compounds and to a lesser extent PAHs with ≥ 4 rings. Phenanthrene is the main component with a percentage of ca. 30 % (see CSR Chapter 1.).


Data on the biodegradation of anthracene oil in surface water and in sediment is not available. Due to its complex composition, it is technically not practical in many cases to determine its biodegradation properties applying standard test procedures. But the biodegradation properties of anthracene oil can be described using data arising from important constituents of anthracene oil. In combination, these data are assessed to characterise the biodegradation properties of anthracene oil satisfactorily.


Besides the main constituent phenanthrene, three other constituents of the substance are considered to be relevant in the characterisation of biodegradation in water and sediment of anthracene oil. These are selected regarding their abundance in anthracene oil (see CSR Chapter 1.2. Composition of the substance - boundary composition) and regarding their biodegradation characteristics. The constituents are of increasing size and log Kow and have a low water solubility (below 1 mg/L, see EU RAR of COAL-TAR PITCH; HIGH TEMPERATURE; Table 1.6, p 18), properties that greatly affect biodegradation performance of PAH. Benzo[a]pyrene is present in anthracene oil only in concentrations below 0.005 % and is thus not taken into account.


Information available on the biodegradation of anthracene oil itself and of its four PAH constituents was already assessed in the context of REACH Regulation (1907/2006) by different authorities or regulatory bodies. Data are collected in the SVHC support documents prepared by ECHA (Member State Committee). This information is summarised in the five study records of this endpoint.


  -  ECHA 2009; SVHC support document - anthracene oil; excerpt on simulation testing in surface water and sediments


  -  ECHA 2018; SVHC support document - phenanthrene; excerpt on simulation testing in surface water and sediment


  -  ECHA 2008; SVHC support document - anthracene; excerpt on simulation testing in surface water and sediment


  -  ECHA 2018; SVHC support document - fluoranthene; excerpt on simulation testing in surface water and sediment


  -  ECHA 2018; SVHC support document - pyrene; excerpt on simulation testing in surface water and sediment


The information in these study records is frequently of general nature. Data are not systematically separated covering the two different compartments water and sediment. Therefore, the information is extracted and presented in the study records as present in the respective SVHC support documents.


 


Concurrent information on biodegradation in surface water


An aerobic simulation biodegradation test according to OECD TG 309 could not be located either for anthracene oil or for constituents of anthracene oil. Thus, specific information on mineralisation half-lives of anthracene oil and its relevant constituents is not available.


But in general, it is known (see study records on excerpts of SVHC support documents), that smaller size PAH with up to four rings are biodegradable under aerobic conditions. Biodegradation rates decrease with increasing size of PAH and are very slow for PAH with four and more aromatic rings. This is caused by factors like bacterial uptake rate and bioavailability and may be due to higher absorption to organic matter of larger size, higher molecular weight PAH.


Information on aerobic biodegradation in water of anthracene oil constituents is scarce. Most information results from experiments with water obtained from pre-contaminated sites like former gas plants or oil/PAH-contaminated estuaries. Biodegradation is increased under these conditions. If microorganisms in water or sediment are given the opportunity to adapt to PAH, biodegradation will increase. Unfortunately, preadaptation conditions are not clearly defined or described. Consequently, differing amounts of mineralisation or half-lives have been determined.


Based on the information identified, a valid half-life for the biodegradation in water of anthracene oil or relevant anthracene oil constituents is not available. But, Mackay et al. (1992) estimated half-lives in the different environmental compartments based on model calculations and literature research.


 


Ranking of PAH in different half-life classes and corresponding half-lives at 20 °C (Mackay et al. 1992)


 














































Compound



Water



Sediment



 



Class



Half-life [d]



Class



Half-life [d]



Phenanthrene



4



13 - 42



7



420 - 1250



Anthracene



4



13 - 42



7



420 - 1250



Fluoranthene



4



13 - 42



8



> 1250



Pyrene



5



42 - 125



8



> 1250



 


For water, half-lives at 20 °C between 13 and 42 days and between 42 and 125 days (class 4 and class 5, respectively)) were estimated. Phenanthrene, anthracene, and fluoranthene belong to class 4, pyrene to class 5. When compared to the P and vP criteria of REACH regulation, Annex XIII (40 and 60 days, respectively), only the upper border of the half-life range of class 4 and class 5 exceeds the respective criterion.


The half-life estimates are valid for a temperature of 20 °C. For regulatory purposes, simulation biodegradation studies should be performed at a temperature of 12 °C (compare ECHA guidance document (IR&CSA) Chapter R.7b: Endpoint specific guidance, p 221 - version 4.0, June 2017, average temperature of European surface waters). At this temperature, half-lives will be much lower.


Taking into account, that half-lives are not distinct values and will be different for individual substances and that the highest half-life estimate (125 days) is far above the vP criterion of REACH regulation, anthracene oil is identified as vP. This categorisation is supported when considering that after correction to 12 °C half-lives will even be lower.


More detailed information on biodegradation data of anthracene oil, phenanthrene, anthracene, fluoranthene, and pyrene in water is presented in the respective study records.


 


Concurrent information on biodegradation in sediment


Basic information provides only one guideline study according to OECD TG 308 (test substance phenanthrene). Other biodegradation studies in sediment have been performed with the focus on sediments contaminated at different levels and oils spills. Overall, basically no biodegradation in sediment was found under anoxic conditions. Under aerobic conditions, biodegradation was slow especially in pristine sediments and in sediments obtained from deeper sediment layers. Biodegradation rates increased when sediments were collected close to the sediment surface and when microorganisms were pre-adapted by oil/PAH contamination.


The half-life of anthracene oil in sediment presented here is based on a sediment simulation study according to OECD TG 308 using phenanthrene as test substance. After recalculation of experimental data obtained at 20 °C to a temperature of 12 °C (the recommended temperature for regulatory purposes), half-lives between 216 and 319 days were determined. Based on their structure and physical-chemical properties (water solubility, log Kow) it can be expected that half-lives of anthracene, fluoranthene, and pyrene in sediment will certainly not be lower but very likely higher than the half-life determined for phenanthrene. As the half-life of phenanthrene in sediment exceeds the vP criterion of REACH regulation, Annex XIII, the half-live of anthracene oil will exceed the vP criterion for sediment as well.


Based on the information identified, a valid half-life for the biodegradation in sediment of anthracene oil or relevant anthracene oil constituents except phenanthrene is not available. Mackay et al. (1992) estimated half-lives in the different environmental compartments based on model calculations and literature research (see table above). For sediment, half-lives at 20 °C between 420 and > 1250 days (class 4 and 5) were estimated. This supports identification of anthracene oil as vP, especially when considering that after correction to 12 °C half-lives will be even lower.


More detailed information on biodegradation data of anthracene oil, phenanthrene, anthracene, fluoranthene, and pyrene in water is presented in the respective study records.