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Endpoint:
adsorption / desorption
Remarks:
adsorption/desorption
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Special protocol developed for sampling by Royal haskoning: "Sampling Instructions for Analysis of Polycyclic Musks in Activated Sludge and Sewage Treatment Plant Effluent". Included in study as Annex G.
Principles of method if other than guideline:
The activated sludge- water partitioning coefficient was determined by measuring AHTN in samples obtained throughout Southern Europe and Berlin. Effluent and sludge were sampled simultaneously.
GLP compliance:
yes
Media:
sewage sludge
Radiolabelling:
yes
Analytical monitoring:
not specified
Details on sampling:
Sampling was conducted under normal dry weather conditions in the period between May and September 2004. The sampling in Berlin took place in May and October 2004. In order to assess the temporal and spatial variability, stack samples of activated sludge and effluent were taken at four times with intervals of at least 14 days for Italy, Spain and Greece and two times for Berlin.
Computational methods:
The analysis of the concentrations was based on the 10log transform of the observed concentrations.
Type:
Kd
Value:
9 120
% Org. carbon:
> 240 - < 290
Remarks on result:
other: g/kg dw
Recovery of test material:
Analytical recovery in sludge ranged from 76 to 125% with an average of 105% and coefficient of variation (CV) of 12.2%. In effluent, the analytical recovery ranged from 68 to 167% with an average of 91% and CV of 14.4%.
Local recovery in sludge ranged from 72 to 101% with an average of 86% and coefficient of variation (CV) of 14%. In effluent, the analytical recovery ranged from 44 to 127% with an average of 82% and CV of 20%.
Transformation products:
not measured
Statistics:
For AHTN in sludge and effluent it can be concluded that the observed variance is mainly caused by the local differences. The variation between sludge samples is only 2.5 % due to analytical error, whereas for effluent samples the analytical error contributes for 21 % in the AHTN variability.

If the log Kd-value is constant and independent of the AHTN concentration, the relation between log Csludge and log Ceffluent is a straight line with a slope of 45º. Based on the data and this assumption, the values for the 18 STPs in this study (including 3 plants from Berlin) for AHTN is log Kd = 3.96.

In fact a better curve fitting was achieved by AHTN: (Csludge)0.67= 5.35·Ceffluent.

This means that Kd is not really constant, but according to this data set, the value of Kd increases at higher concentrations in sludge, or in other words, the adsorptive power increases at higher concentrations.

Validity criteria fulfilled:
not applicable
Remarks:
AHTN sampled at locations in Europe
Conclusions:
Assuming that Kd is constant with a varying AHTN concentration, the log Kd is 3.96.
Executive summary:

Concentrations of the polycyclic musks HHCB and AHTN have been measured in 15 sewage treatment plants in Southern Europe (Italy, Spain and Greece) and 3 plants in Berlin, Germany. No correlation could be found between the type of plant design or performance and the concentration level. Differences between treatment plants appear to be related to local differences in the per capita use volume of the local population. The ratios between concentrations in sludge and effluents are generally in good agreement with equilibrium partitioning; however, local differences between plants may occur. These differences may be explained by a non-linear adsorption isotherm to the suspended solids on the one hand and partitioning to dissolved organic macromolecules on the other hand. Based on comparison of recent available data for more than 110 plants in other countries of Europe, the 90th- percentile values of Southern Europe represent the realistic worst-case for Europe.

The median of the AHTN concentration in sludge is 5.5 mg/kg dw and the 90th percentile 11 mg/kg dw. In the effluent, the median AHTN concentration is 0.6µg/kg and the 90th percentile 1.3µg/l.

Endpoint:
adsorption / desorption
Remarks:
adsorption
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
22 November 2000 - 16 October 2002
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: A thesis describing the research conducted by a Ph.D. student at the Institute for Risk Assessment Sciences (IRAS), University of Utrecht (NL).
Reason / purpose:
reference to same study
Guideline:
other: described in thesis
Principles of method if other than guideline:
Biodegradation rate constants of AHTN in the aeration tank of a sewage treatment plant (STP) are studied in vitro. A general model is described to determine the rate-limiting factor in the biodegradation process, from which the Koc can be calculated.
GLP compliance:
not specified
Type of method:
other:
Media:
sewage sludge
Radiolabelling:
no
Test temperature:
Room temperature
Analytical monitoring:
not required
Details on sampling:
Experiments were conducted in duplicate with activated sludge obtained from the oxidation tank of the STP in De Bilt (The Netherlands) on November 22, 2000. Sludge was collected and aerated to maintain bacterial activity during transportation.
Computational methods:
The rate constant of microbial degradation and the rate constant of evaporation are used to calculated the Koc.
The microbial degradation is calculated by taking the quotient of the rate constants k1 and k2 representing the mass transfer of the chemical from the organic to the aqueous phase, and from the aqueous to the organic phase, respectively.
Type:
log Koc
Remarks:
"Apparent" value that is based on the biodegradation rate constants of chemicals in activated sludge.
Value:
3.1
Remarks on result:
other: Organic carbon is determined but not reported. Temperature is probably room temperature.
Type:
log Koc
Remarks:
True partition coefficient
Value:
3.8
Remarks on result:
other: Organic carbon is determined but not reported. Temperature is room temperature.
Recovery of test material:
Recoveries of the procedure were between 85-110%.
Transformation products:
not measured
Details on results (Batch equilibrium method):
The organic carbon content was stable during the entire experiment.
Model curves, shown in Figure 1 (attached), are in agreement with the measured values, and it can be concluded that the model describes the data rather well.
Koc obtained from the model is lower than the independently measured data.

Optimized values (± SEM) obtained from the regression analysis on the model.

Kbio, true(h-1)

0.023 ± 0.010

kev (h-1)

0.0085 ± 0.0002

log Koc

3.1±0.2

 

Kbio, true: Rate constant microbial degradation

kev (h-1): Evaporation rate constant

Validity criteria fulfilled:
yes
Remarks:
based on recovery
Conclusions:
Microbial degradation is the rate-limiting step in the biodegradation in an aeriation tank with a half life of 92h. The calculated Koc is 3.1 based on the biodegradation rate constants of chemicals in activated sludge.
Executive summary:

A mathematical model to determine free concentration based biodegradation rate constants of chemicals in activated sludge was developed. The model is based on the assumption that only the free concentration is available for microbial degradation and therefore two processes can limit the biodegradation rate. Either desorption of the chemical from the matrix to the aqueous phase, or the microbial degradation capacity is rate-limiting. Calculations show that a comparison of the decrease of free and total concentrations of the chemicals in time, together with an independent measurement of the organic carbon/water partition coefficient (Koc gives information about the rate-limiting step of the biodegradation process). This information can be used as a tool to optimize the removal of chemicals in STPs. Experimental results show that for AHTN the biodegradation half-life of AHTN in the aeration tank is 92h, and that microbial degradation itself is the rate-limiting process.

Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: According to OECD guideline, but no GLP compliance data included.
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study
Qualifier:
according to
Guideline:
OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))
GLP compliance:
not specified
Type of method:
HPLC estimation method
Media:
other: no media
Radiolabelling:
no
Details on study design: HPLC method:
AHTN was separeted by chromatography under standard HPLC conditions on a cyano column. The retention times were determined. The corresponding capacity factors (k’ and log k’) were calculated from the dead volume of the HPLC system.
The log k’ values of the reference substances and their coefficients of adsorption (log KOC) were used to calculate a calibration function (log k’ against log KOC). The coefficients of adsorption (log KOC) of AHTN was calculated from the log k’ values using calibration lines.
Reference substances were Formamid, Acetanilid, Atrazin, Monuron, Triapenthenol, Linuron, Fenthion, Trifluralin.

HPLC Parameter
Pump: Gynkotek M480 Gradientenpump
Autosampler/Injector: Gynkotek GINA 160
Column: Zorbax CN, 5 μm, 250 x 4.6 mm
Precolumn: Zorbax CN, 5 μm, 10 x 4.6 mm
Mobile Phase: Methanol / Water (60% / 40% (v/v)
Rate: 1,0 mL/min
Injection volume: 20 μL
Substance injected: 1.0 - 1,6 μg
Temperature: 40 °C
Detector: Gynkotek UVD 160S/320S
Data system: Gynkosoft Vers.5.50
Analytical monitoring:
not required
Type:
log Koc
Value:
3.41
Temp.:
40 °C
Type:
Koc
Value:
2 563
Temp.:
40 °C
Transformation products:
not measured
Conclusions:
Log Koc is 3.41, indicating a strong adsorption to soils.
Executive summary:

The log Koc and Koc were estimated using the HPLC screening method according to draft OECD Guideline 121. Suitable test and reference substances were subjected to chromatography under standard HPLC conditions on a cyano column and the retention times were determined. The corresponding capacity factors (k’ and log k’) were calculated from the dead volume of the HPLC system and the retention times determined. The log k’ values of the reference substances and their coefficients of adsorption (log Koc) were used to calculate a calibration function (log k’ against log Koc). The coefficients of adsorption (log Koc) of AHTN was calculated from the log k’ values using calibration lines. The estimation of the adsorption coefficients (log Koc) produced a relatively high value of 3.41. Other polycyclic musks were also examined and in this range. This indicates strong sorption of the substances to soils.

Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: According to OECD guideline, but no GLP compliance data included.
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study
Qualifier:
according to
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
GLP compliance:
not specified
Type of method:
HPLC estimation method
Media:
soil
Radiolabelling:
no
Details on study design: HPLC method:
AHTN was separeted by chromatography under standard HPLC conditions on a cyano column. The retention times were determined. The corresponding capacity factors (k’ and log k’) were calculated from the dead volume of the HPLC system.
Analytical monitoring:
not required
Details on test conditions:
Soil used: Borstel soil (sandy); Latrop soil (clayey); Friesland soil (humic).
Type:
Kd
Value:
162.6
Temp.:
20 °C
% Org. carbon:
1.2
Remarks on result:
other: Borstel soil; pH=5.4
Type:
Kd
Value:
150
Temp.:
20 °C
% Org. carbon:
3.1
Remarks on result:
other: Latrop soil; pH=6.1
Type:
Kd
Value:
660
Temp.:
25 °C
% Org. carbon:
5.8
Remarks on result:
other: Friesland (D); pH=5.1
Type:
Koc
Value:
13 550
Temp.:
20 °C
% Org. carbon:
1.2
Remarks on result:
other: Borstel soil; pH=5.4
Type:
Koc
Value:
4 839
Temp.:
20 °C
% Org. carbon:
3.1
Remarks on result:
other: Latrop soil; pH=6.1
Type:
Koc
Value:
11 383
Temp.:
20 °C
% Org. carbon:
5.1
Remarks on result:
other: Friesland (D); pH=5.1
Recovery of test material:
Soil samples were extracted to calculate a total mass balance. The recoveries for the Borstel soil (sandy); Latrop soil (clayey); Friesland soil (humic) and seage sludge (Klärschlamm) were 113%, 117, 180% and 280%. The balances were above 100% due to the presence of AHTN in the samples prior to addition. The latter recovery was so extemely high that no absorption coefficient was calculated.
Sample no.:
#1
Duration:
24 h
% Adsorption:
76.4
Sample no.:
#2
Duration:
24 h
% Adsorption:
82.7
Sample no.:
#3
Duration:
24 h
% Adsorption:
94.1
Sample no.:
#4
Duration:
24 h
% Adsorption:
96.8
Sample no.:
#1
Duration:
24 h
% Desorption:
21.5
Sample no.:
#2
Duration:
24 h
% Desorption:
18.1
Sample no.:
#3
Duration:
24 h
% Desorption:
4.9
Sample no.:
#4
Duration:
24 h
% Desorption:
1.5
Transformation products:
not measured
Details on results (Batch equilibrium method):
Adsorption equilibria reached after about 2 hours.
For isotherm and desorption test, an additional 24 hours was selected.
Validity criteria fulfilled:
yes
Remarks:
Control samples and blanks were included.
Conclusions:
AHTN strongly absorbs to the soil samples. The log Koc ranged from 4800-13600 cm3/g for sandy, clay and humic soil.
Executive summary:

The sorption characteristics of AHTN was determined on three representative soils in accordance with OECD Guideline 106. The soils differed in their characteristics: Borstel soil (sandy); Latrop soil (clayey); Friesland soil (humic). The factors determined were adsorption kinetics, adsorption isotherms (according to Freundlich) and the desorption behaviour. The experiments regarding adsorption kinetics showed that the sorption equilibria were reached after a short period (approx. 2 hours). The Freundlich adsorption isotherms showed good correlations for all substances and soils. The adsorption coefficients (Kd) were in the range of 150 to 660 cm3/g. The normalization to the organic carbon content in the soils yielded Koc values of between 4800 and 13600 cm3/g for Tonalid. These values show that the substances are bound very strongly to the soils. The desorption tests showed that the adsorption is not reversible and a maximum of only 1-21.5% of the sorbed quantities of the substances was desorbed.

Endpoint:
adsorption / desorption
Remarks:
adsorption
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: KOCWIN v2.00 - Model to estimate the soil adsorption coeffiecient (Koc) of organic compounds, v2.00, February 2009, US Environmental Protection Agency (2000-2008).
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6
Reason / purpose:
reference to same study
Qualifier:
no guideline required
Principles of method if other than guideline:
Estimation methods for predicting Koc values for hydrophobic organic compounds based upon the octanol/water partition coefficient.
GLP compliance:
no
Computational methods:
log Kow can be used to estimate Koc for non-polar compounds. The equation derived by the non-polar (no correction factor) regression is:
log Koc = 0.55313 Log Kow + 0.9251 + ΣPfN
(n = 68, r2 = 0.877, std dev = 0.478, avg dev = 0.371)
where ΣPfN is the summation of the products of all applicable correction factor coefficients multiplied by the number of times (N) that factor is counted for the structure.
Reference: Doucette, W.J. 2000. Soil and sediment sorption coefficients. In: Handbook of Property Estimation Methods, Environmental and Health Sciences. R.S. Boethling & D. Mackay (Eds.), Boca Raton, FL: Lewis Publishers (ISBN 1-56670-456-1).
Type:
log Koc
Value:
> 4.1 - < 4.3
Remarks on result:
other: Method based on Log Kow with a correction factor for the ketone
Type:
log Koc
Value:
> 4.68 - < 4.95
Remarks on result:
other: Method based on Log Kow for non-polar molecules
Transformation products:
not measured
Statistics:
Linear regression, for details see Koc WIN model

Although AHTN is very hydrophobic, it is not completely non-polar due to the presence of a ketone. Hence, the following equations are used to calculate Koc on the basis of Log Kow.

 

Koc Estimate from Log Kow:

Log Kow varies from 5.4 to 5.7.

Log Koc = 0.55313·Log Kow + 0.9251.

The uncorrected Log Koc ranges from 3.91 to 4.08.

Correction factor for the ketone group is 0.1956

Corrected log Koc ranges from 4.11 - 4.27.

Estimated Koc:12810 - 18770L/kg.

 

Koc Estimate from Log Kow for non-polar molecules:

Log Kow varies from 5.4 to 5.7.

Log Koc = 0.8679·Log Kow - 0.0004.

Corrected log Koc ranges from 4.68 - 4.95.

Validity criteria fulfilled:
not applicable
Conclusions:
log Koc estimated from log Kow is 4.2.
Executive summary:

The Koc can be calculated by using the log Kow. The calculation is based on linear regression and also includes correction factor coefficients.

Log Koc estimated ranges from 4.1 to 4.9.

Endpoint:
adsorption / desorption
Remarks:
adsorption
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: KOCWIN v2.00 - Model to estimate the soil adsorption coeffiecient (Koc) of organic compounds, v2.00, February 2009, US Environmental Protection Agency (2000-2008).
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6
Reason / purpose:
reference to same study
Qualifier:
no guideline required
Principles of method if other than guideline:
Estimation methods for predicting Koc values for hydrophobic organic compounds based upon the first-order molecular connectivity index (MCI).
GLP compliance:
no
Computational methods:
Molecular Connectivity Index:
The equation derived by the non-polar (no correction factor) regression is:
log Koc = 0.5213 MCI + 0.60
(n = 69, r2 = 0.967, std dev = 0.247, avg dev = 0.199)
Where MCI is the Molecular Connectivity Index.
Adding in the correction factor regression yields the final MCI equation:
log Koc = 0.5213 MCI + 0.60 + ΣPfN
where ΣPfN is the summation of the products of all applicable correction factor coefficients multiplied by the number of times (N) that factor is counted for the structure.
Reference: Meylan, W., P.H. Howard and R.S. Boethling. 1992. Molecular topology/fragment contribution method for predicting soil sorption coefficients. Environ. Sci. Technol. 26: 1560-1567.
Type:
log Koc
Value:
3.94
Remarks on result:
other: Calculation based on Molecular Connectivity Index with a correction factor for the ketone
Transformation products:
not measured
Statistics:
Linear regression, for details see Koc WIN model

Although AHTN is very hydrophobic, it is not completely non-polar due to the presence of a ketone. Hence, the following equations are used to calculate Koc on the basis of molecular connectivity and Log Kow.

 

Koc Estimate from Molecular Connectivity Index (MCI):

First Order Molecular Connectivity Index:  MCI = 8.570

log Koc = 0.5213·MCI + 0.60 = 5.06 (uncorrected)

Correction factor for the ketone group is -1.1290

Corrected log Koc = 5.06 - 1.1290 = 3.94.

Estimated Koc:8678L/kg.

Validity criteria fulfilled:
not applicable
Conclusions:
log Koc estimated from the Molecular Connectivity Index is 3.9.
Executive summary:

The Koc can be calculated by utilizing a Molecular Connectivity Index. Log Koc estimated from the Molecular Connectivity Index is 5.07.

Description of key information

The Koc for the test item is found to be highly variable, depending on the environmental matrix and no single representative value was established. The estimated partition coefficient based on the EUSES QSAR for predominantly hydrophobics falls well within the range and has been selected.

Key value for chemical safety assessment

Koc at 20 °C:
29 512

Additional information

The observed variability of log Kd-values in the study of Blok between 3.6 and 4.3 (extremes) is a factor of 5. Müller reported a log Kd ranging from 4.1 to 5.0. Doi reported a log Kd of 4.06. Koc is also observed to vary. The HPLC screening method used by Müller gives a log Koc of 3.41, while measurements in soil varied from 3.7 to 4.13. The EU Risk Assessment mentions values for log Koc of 3.1 to 4.8 in activated sludge.

The log Koc calculated on the basis of Log Kow were more in line with the experimental results. The EU Risk Assessment used the formula Log Koc = 0.81·log Kow + 0.1 (for predominantly hydrophobics) and a log Kow of 5.4 to obtain a log Koc of 4.47. Note that the log Kow of 5.7 (Rudio 1993) results in log Koc of 4.7. In the v2.00 version of KocWin, the new equation for the Koc calculation gives log Koc 4.9. The differences in the calculations are marginal, when considering the background of the wide distribution of Koc values measured in the environment. .

Empirical values of Kd and Koc vary considerably. All calculated values fall within the range of experimentally derived data and for the purpose of consistency, the calculated Koc based on the Kow (EUSES) as reported in the EU Risk Assessment Report of AHTN has been used.

Desorption test by Müller showed that adsorption is not reversible.