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Environmental fate & pathways

Biodegradation in soil

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Reference
Endpoint:
biodegradation in soil: simulation testing
Type of information:
other: Assessment report QSAR and Experimental data
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Justification for type of information:
Rosin and rosin salts are UVCB substances and the main constituents for all category members are resin acids and/or their salts. Oligomers of resin acids (mainly dimers) can also be present in rosin and rosin salt substances. Standard biodegradation studies are not really appropriate for whole substance UVCBs and therefore as much is reasonably practicable, biodegradation of the individual consituents as a whole needs to be considered. In order to prioritise the consituents that may require further testing a PBT screening assessment of Rosin Adducts and Rosin Adducts Salts substances was undertaken. The logic being that if a consituent is both Persistent and Bioaccumulative then further testing on these constituents would be required.

Guidance for mono-constituents is available from ECHA; however, for complex substances such as Unknown or Variable Composition, Complex reaction products or Biological materials (UVCBs) there is currently little guidance on how the PBT/vPvB assessment should be conducted. A pragmatic approach for UVCBs is to evaluate all the individual constituents present in the substance at a concentration of ≥0.1% for their PBT properties.

As this is a UVCB substance it is not possible to identify every single constituent at a concentration of 0.1% (which numbers thousands)and detailed analysis of each individual constituent within the substance is not available. As such, a list of representative constituents has been developed from information in the Substance Identity Profiles. All identified representative constituents were assessed individually for their P and B properties.

Any constituents that are both P and B will be taken forward for further simulation studies.
Principles of method if other than guideline:
A Tiered approach to screening for the substance's PBT properties was employed. The Tiered approach adopted aims to screen the constituents based on their P and B properties using available data. Those constituents that are identified as being potentially P/vP and B/vB are then taken for further assessment of their PBT/vPvB properties.

Persistence
To assess the probability that each constituent is Persistent or not, QSAR models and any readily available experimental data has been used. Experimental data has been given the highest priority over QSARs and where available conclusions have been drawn on available experimental data. QSAR data on the probability for persistence was modelled using BIOWIN 4.10 models (BIOWIN 2, BIOWIN 3, BIOWIN 6) (USEPA, 2012).

Bioaccumulation
First the log Kow and Koa of each constituent was estimated using KOWWIN and KOAWIN models (USEPA, 2012). This database also provided some experimental Log Kow/Log Koa values. The log Kow and the log Koa were used as a first screen to conclude if a constituent was not B/vB.

The guidelines suggest that substances with a log Kow of >10 and/or an average maximum diameter (Dmaxav) of >1.7 nm are less likely to be bioavailable due to their very large molecular size and inability to cross biological membranes. This data has been included in the assessment to increase confidence that a constituent is unlikely to be bioaccumulative. Constituents with these characteristics are also considered to be not B for air-breathing organisms.

In addition to any readily available experimental data predicted BCFs using the BCFBAF regression model based on log Kow and the Arnot-Gobas (upper trophic) model were derived for each constituent. The BCFBAF regression model is considered a lower tier model compared to the Arnot-Gobas (upper trophic) model. The BCFBAF model uses the log Kow and a regression equation to predict the BCF of the substance and can be used for ionic and non-ionic substances.
GLP compliance:
no
Soil classification:
not specified
Parent/product:
parent
Remarks on result:
not measured/tested
Transformation products:
not specified

Screening Tier 1 Persistence

There is an OECD 301B ready biodegradation study available for Abietal which is one of the Neutral Fraction Aldehydes which showed that Abietal is not persistent. This data can be read-across to the other Neutral Aldehydes and therefore these are not considered persistent. The persistence assessment of the other constituents relies on the BIOWIN QSARs. Seven constituents, however, were too large to calculate the QSARs these have therefore been assumed to be persistent as a worst case. This data indicates that 12 of the 62 constituents are either not P or Predicted not P of the remaining 50 constituents 43 are Predicted P and for 7 persistence was not possible to be calculated.

Results for Screening of P

P conclusion

Number of constituents that met the criterion

Not P

5 of 62

Predicted Not P

7 of 62

Predicted P

43 of 62

P

0 of 62

vP

0 of 62

Unable to calculate

7 of 62

 

 

 

Screening Tier 1 Bioaccumulation

Of the 62 constituents, none could be omitted from further assessment as they were identified as Potentially B and require further assessment. It is noted that the 62 constituents were screened as potentially B since they presented a log Kow >2 and a log Koa >5, which indicates bioaccumulation in air-breathing organisms. All constituents were screened as Potentially B for aquatic organisms due to having a log Kow >4.5. See Appendix 2 for exact values. As suggested above, further assessment of the risk of bioaccumulation in air‑breathing organisms cannot be

assessed competently at present with the heavy information burden that would be required for each of these 62 constituents. Further assessment will therefore be based on aquatic organisms only

Results for Screening of B

B conclusion

Number of constituents that met the criteria

Not B

0 of 62

Potentially B/vB - needs further assessment

62 of 62

 

Tier 2 Assessment

Persistence

Without further experimental data on the constituents assessment of Persistence is not viable. As such the bioaccumulation assessment using QSARs was undertaken first to identify any specific constituents that may need further data on their persistence to be sought.

Bioaccumulation

Resin acids are the main constituents of rosin and rosin salts. Measured BCF values obtained from a bioaccumulation study with Oncorhynchus mykiss are available for nine resin acids (abietic, dehydroabietic, chlorodehydroabietic, dichlorodehydroabietic, neoabietic, pimaric, isopimaric, sandaracopimaric and palustric acids) and these show a range of BCFs between 23 and 129 (Niimi and Lee 1992). In this study, fish that were exposed to mean waterborne concentrations of 0.7 to 3.6 µg/L for 20 days, followed by a 10-day depuration period. No detectable levels of free or conjugated acids were found in fish sampled 4 to 10 days into the depuration period, therefore no half-lives could be calculated. However, based on initial chemical concentrations, it was suggested that the half-lives of these acids were <4 days.

Burggraaf et al. (1996) determined BCF values for mussels (Hyridella menziesi) exposed to effluent from a pulp and paper mill. Concentrations of resin acids (pimaric acid, isopimaric acid, dehydroabietic acid, abietic acid and 14 -chlorodehydroabietic acid) were analysed in mussels and in the effluent for a 28d exposure phase, followed by a 21d depuration phase. BCF values for the individual resin acids ranged from 110 to 330 L/kg. The BCF values determined in these studies are far below the bioaccumulation threshold, therefore resin acids are not considered to be bioaccumulative.

The PACT assessments conducted for rosin, hydrogenated rosin and resin acids and rosin acids, sodium salts concluded that “In conclusion it can be stated that, based on measured BCF-values in fish and mussels, the substance does not fulfil the B/vB-criteria.” (Tukes 2015a, 2015b, 2015c, ECB, 2008)

QSAR models were therefore used to fill the remaining data gaps for the constituents in this assessment. Of the 62 constituents that required further assessment, eight had experimental data that showed that they were not bioaccumulative. Five of the constituents (Neutral Aldehydes) were predicted to potentially be B/vB. The remaining 50 constituents they all reported BCFs <2000 L/kg. In addition, 32 of the constituents were reported to have a Log Kow of >10 and/or a Dmaxav of >1.7, which offers greater confidence that these substances are not expected to be bioaccumulative. As a result, the 62 constituents were concluded to be Predicted Not B.

Results from Tier 2 assessment

B conclusion

Number of constituents that met the criterion

Not B

8 of 62

Predicted Not B

49 of 62

Predicted B

5 of 62

Predicted vB

0 of 62

B

0 of 62

vB

0 of 62

 

Conclusion on Persistence and Bioaccumulation

Following the Screening assessment detailed above the data gathered suggests that based on QSARs only the Neutral Fraction Aldehydes have a potential to be PBT. Experiment data on Abietal shows it to be not persistent and therefore not PBT/vPvB. All Neutral Fraction Aldehydes are therefore not persistent and therefore not PBT/vPvB. For the remaining constituents, none of the constituents are expected to be Bioaccumulative. It is noted that, even if the data on bioaccumulation is exclusively from QSARs for this substance, the models used are reliable, well documented and well known and fit these types of constituents, even those substances that have a higher Kow than the training data set. The Predicted BCF values in both models were much lower than the 2000 L/kg criterion for B in the Regulation and therefore there is high confidence that there are no constituents of concern in this substance.

Final conclusion

PBT conclusion

Number of constituents that met the criterion

Not PBT/vPvB

62 of 62

Potentially PBT

0 of 62

Potentially vPvB

0 of 62

Conclusions:
Following the Screening assessment detailed above the data gathered suggests that based on QSARs only the Neutral Fraction Aldehydes have a potential to be PBT. Experiment data on Abietal shows it to be not persistent and therefore not PBT/vPvB. All Neutral Fraction Aldehydes are therefore not persistent and therefore not PBT/vPvB. For the remaining constituents, none of the constituents are expected to be Bioaccumulative (Table 10). It is noted that, even if the data on bioaccumulation is exclusively from QSARs for this substance, the models used are reliable, well documented and well known and fit these types of constituents, even those substances that have a higher Kow than the training data set. The Predicted BCF values in both models were much lower than the 2000 L/kg criterion for B in the Regulation and therefore there is high confidence that there are no constituents of concern in this substance. Following the Screening assessment detailed above the data gathered suggests that based on QSARs only the Neutral Fraction Aldehydes have a potential to be PBT. Experiment data on Abietal shows it to be not persistent and therefore not PBT/vPvB. All Neutral Fraction Aldehydes are therefore not persistent and therefore not PBT/vPvB. For the remaining constituents, none of the constituents are expected to be Bioaccumulative (Table 10). It is noted that, even if the data on bioaccumulation is exclusively from QSARs for this substance, the models used are reliable, well documented and well known and fit these types of constituents, even those substances that have a higher Kow than the training data set. The Predicted BCF values in both models were much lower than the 2000 L/kg criterion for B in the Regulation and therefore there is high confidence that there are no constituents of concern in this substance. Therefore, further simulation testing is not required on any of the constiuents.
Executive summary:

Rosin and rosin salts are UVCB substances and the main constituents for all category members are resin acids and/or their salts. Oligomers of resin acids (mainly dimers) can also be present in rosin and rosin salt substances. Standard biodegradation studies are not really appropriate for whole substance UVCBs and therefore as much is reasonably practicable, biodegradation of the individual consituents as a whole needs to be considered. In order to prioritise the consituents that may require further testing a PBT screening assessment of Rosin Adducts and Rosin Adducts Salts substances was undertaken. The logic being that if a consituent is both Persistent and Bioaccumulative then further testing on these constituents would be required.

Guidance for mono-constituents is available from ECHA; however, for complex substances such as Unknown or Variable Composition, Complex reaction products or Biological materials (UVCBs) there is currently little guidance on how the PBT/vPvB assessment should be conducted. A pragmatic approach for UVCBs is to evaluate all the individual constituents present in the substance at a concentration of ≥0.1% for their PBT properties.

As this is a UVCB substance it is not possible to identify every single constituent at a concentration of 0.1% (which numbers thousands)and detailed analysis of each individual constituent within the substance is not available. As such, a list of representative constituents has been developed from information in the Substance Identity Profiles. All identified representative constituents were assessed individually for their P and B properties.

Any constituents that are both P and B will be taken forward for further simulation studies.

Following the Screening assessment detailed above the data gathered suggests that based on QSARs only the Neutral Fraction Aldehydes have a potential to be PBT. Experiment data on Abietal shows it to be not persistent and therefore not PBT/vPvB. All Neutral Fraction Aldehydes are therefore not persistent and therefore not PBT/vPvB. For the remaining constituents, none of the constituents are expected to be Bioaccumulative (Table 10). It is noted that, even if the data on bioaccumulation is exclusively from QSARs for this substance, the models used are reliable, well documented and well known and fit these types of constituents, even those substances that have a higher Kow than the training data set. The Predicted BCF values in both models were much lower than the 2000 L/kg criterion for B in the Regulation and therefore there is high confidence that there are no constituents of concern in this substance.

Following the Screening assessment detailed above the data gathered suggests that based on QSARs only the Neutral Fraction Aldehydes have a potential to be PBT. Experiment data on Abietal shows it to be not persistent and therefore not PBT/vPvB. All Neutral Fraction Aldehydes are therefore not persistent and therefore not PBT/vPvB. For the remaining constituents, none of the constituents are expected to be Bioaccumulative (Table 10). It is noted that, even if the data on bioaccumulation is exclusively from QSARs for this substance, the models used are reliable, well documented and well known and fit these types of constituents, even those substances that have a higher Kow than the training data set. The Predicted BCF values in both models were much lower than the 2000 L/kg criterion for B in the Regulation and therefore there is high confidence that there are no constituents of concern in this substance. Therefore, further simulation testing is not required on any of the constiuents.

Description of key information

Rosin and rosin salts are UVCB substances and the main constituents for all category members are resin acids and/or their salts. Oligomers of resin acids (mainly dimers) can also be present in rosin and rosin salt substances. Standard biodegradation studies are not really appropriate for whole substance UVCBs and therefore as much is reasonably practicable, biodegradation of the individual consituents as a whole needs to be considered. In order to prioritise the consituents that may require further testing a PBT screening assessment of Rosin Adducts and Rosin Adducts Salts substances was undertaken. The logic being that if a consituent is both Persistent and Bioaccumulative then further testing on these constituents would be required.

Guidance for mono-constituents is available from ECHA; however, for complex substances such as Unknown or Variable Composition, Complex reaction products or Biological materials (UVCBs) there is currently little guidance on how the PBT/vPvB assessment should be conducted. A pragmatic approach for UVCBs is to evaluate all the individual constituents present in the substance at a concentration of ≥0.1% for their PBT properties.

As this is a UVCB substance it is not possible to identify every single constituent at a concentration of 0.1% (which numbers thousands)and detailed analysis of each individual constituent within the substance is not available. As such, a list of representative constituents has been developed from information in the Substance Identity Profiles. All identified representative constituents were assessed individually for their P and B properties.

Any constituents that are both P and B will be taken forward for further simulation studies.

Following the Screening assessment detailed above the data gathered suggests that based on QSARs only the Neutral Fraction Aldehydes have a potential to be PBT. Experiment data on Abietal shows it to be not persistent and therefore not PBT/vPvB. All Neutral Fraction Aldehydes are therefore not persistent and therefore not PBT/vPvB. For the remaining constituents, none of the constituents are expected to be Bioaccumulative (Table 10). It is noted that, even if the data on bioaccumulation is exclusively from QSARs for this substance, the models used are reliable, well documented and well known and fit these types of constituents, even those substances that have a higher Kow than the training data set. The Predicted BCF values in both models were much lower than the 2000 L/kg criterion for B in the Regulation and therefore there is high confidence that there are no constituents of concern in this substance.

Following the Screening assessment detailed above the data gathered suggests that based on QSARs only the Neutral Fraction Aldehydes have a potential to be PBT. Experiment data on Abietal shows it to be not persistent and therefore not PBT/vPvB. All Neutral Fraction Aldehydes are therefore not persistent and therefore not PBT/vPvB. For the remaining constituents, none of the constituents are expected to be Bioaccumulative (Table 10). It is noted that, even if the data on bioaccumulation is exclusively from QSARs for this substance, the models used are reliable, well documented and well known and fit these types of constituents, even those substances that have a higher Kow than the training data set. The Predicted BCF values in both models were much lower than the 2000 L/kg criterion for B in the Regulation and therefore there is high confidence that there are no constituents of concern in this substance. Therefore, further simulation testing is not required on any of the constiuents.

Key value for chemical safety assessment

Additional information