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EC number: 216-133-4
CAS number: 1506-02-1
Biotic degradation in water and sludge
1. Lee et al. (2001) described a sludge
die-away test using test concentrations of 5 and 50μg/l 14C-AHTN.
Several polar metabolites were detected after 3 days, and after 20 days
the test item was largely biotransformed. Half-life of the parent AHTN
was 12-24 h. This half-life refers to disappearance of the parent
2. A similar die-away test was conducted in
river water (Schaefer and Koper 2007). AHTN was tested at a
concentration of 5μg/l and sludge inoculum 10 mg/l TSS. AHTN steadily
disappeared with an overall half-life of 200 hours, by a combination of
processes, including also volatilisation. By correction for
volatilisation and combining with the data of the abiotic control, it
was shown that the loss of parent material due solely to biodegradation
(therefore primary biodegradation) was 42% after 28 days. The extracts
from the sludge study were combined and analyzed for Kow by HPLC with
on-line radioactivity detection. In this study, log Kow of AHTN was
5.88. Biotransformation products eluted in two major groups. The log Kow
value of the first group is 0.34 - 0.73 and of the second 3.92. Thus it
is concluded that the metabolites are much more polar than the parent
3. Lee et al. (2001) carried out also a
CAS-test with 10μg/l 14C-labelled AHTN in realistic STP operational
conditions (addition of waste water, sludge retention time 10 d,
hydraulic retention time 6 h). A complete mass balance could be derived
and it showed that the total removal of the parent AHTN was 87.5% of
which a half (42.5%) was caused by biotransformation and a half by
sorption (44.3%). Volatilisation played a minor role (3.3%) (Lee et al.
2001, Federle et al. 2002).
4. In another study, concentrations of AHTN
in activated sludge samples were followed for 2 days. The samples were
not additionally spiked and the initial dissolved and total
concentrations were 1.15 and 5.25 μg/l, respectively. Loss due to
volatilisation was also determined. The ‘true biodegradation rate
constant’ based on the dissolved concentration was 0.023 ± 0.010 per
hour. The rate constant based on total concentrations was 0.0075 per
hour (Artola 2002).
No data are available on degradation in
Biodegradation in soil
1. From soils collected in the Netherlands,
several pure cultures of the ubiquitous fungi Aureobasidium pullulans
and Phanerochaete chrysosporium were isolated which were capable
of degrading AHTN and AHTN-alcohol (PFW 1996 and 1997). Approximately
28% of the 64 soil samples degraded AHTN. 80% of AHTN disappeared in 3
weeks in A. pullulans cultures, and AHTN disappeared within 3
days from cultures with the white rot fungus P. chrysosporium.
2. AHTN and HHCB concentrations in 13 field
locations in Baden-Württemberg, Germany, were measured in 2002 and
compared to estimated concentrations after last sludge application.
Different but recorded quantities of sludge had been applied in
different periods to each field and the time from the last sludge
application varied from field to field. Reference fields were also
included (LfU-BW 2003). Using the data in the report, the remaining
AHTN+HHCB concentration after the last application was calculated to be
0.2 % after 13 years, 0.5 % after 7 years, < 0.4 % after 4 years, 1.9 %
after 3 years and < 0.3 % after 3 years, 1,8 after 2 years and 1.3 %
after 1 year. The estimated disappearance reflects the influence of all
losses. On the basis of physical-chemical properties of AHTN and HHCB,
loss via leaching can be considered as very low, whereas volatilization
might have caused a part of disappearance.
3. In a 1-year mesocosm scale a 1-year
die-away study of fragrance materials in four different soils, soil
samples were amended with sludge and contained initially AHTN between
0.1 and 0.27 mg kg-1dwt. A set of soils was amended with sludge and in
addition spiked with AHTN resulting initial concentration of 6 and 13 mg
kg-1dwt. The test trays were placed outdoors. In the spiked soils,
concentrations rapidly decreased during the first month and then
decreased steadily. During the next three months period the soil was
frozen and the concentrations of all test materials remained stable.
After one year, the concentrations of AHTN in unspiked soils ranged from
42 to 61% of the initial concentration. In spiked soils the
concentrations were slightly more variable. Leachate was collected
during the first 3 to 5 months; it was concluded that the influence of
leaching was negligible on the disappearance. The share of
volatilization and degradation of the disappearance were not determined
(DiFrancesco et al. 2004).
The available temporal series of monitoring
data indicate that AHTN is not persistent in sediment. The decrease of
concentrations in sewage sludge, water and suspended mater, which
reflect the reduction of the input of AHTN to sewers over the years, are
followed by a similar decrease of concentrations in sediment. This
phenomenon is illustrated by Figure 1 and Table 2 in the PBT Working
Group Report. Figure 1 illustrates the immediate decrease of AHTB in the
environment in Hessen (by a factor of circa 5) after a decrease in the
use of AHTN starting in the 1990's. Table 2 is reproduced below, and
completed for 2011 monitoring data and data on the use volume in the EU.
Other available sediment monitoring data show a similar trend (European
Figure 1. Trend in the concentrations of
AHTN in Hessen. Note the logarithmic scale (Data from HLUG 2001) (see
Table 2. Decrease of the AHTN concentrations
in samples from STPs along Teltow Canal and sediment, Berlin (compiled
from: Heberer 2002, Fromme et al. 2000, Fromme et al. 2001a, Blok et al.
2005; Balk et al. 2012).
EU use volume, ton/yr
(2008-2011) circa 300
decrease in the concentrations seems to be disproportionally high (a
factor 2 to 10) as compared to the decrease in use volume (a factor of
2). Explanations might be that in the past samples were
over-representing contaminated sites and relevant improvement of the
performance of STPs.
and discussion of persistence
simulation tests are not available for marine water or sediment.
Evidence of relatively fast primary degradation is provided from the
available experiments with sludge, river water and soil. However, the
studies reviewed detected low mineralization rates of AHTN. Instead,
polar metabolites were formed readily and polarity increased over time.
half-life for primary degradation of AHTN in activated sludge was less
than 1 day (Lee et al. 2001, Federle et al. 2002, Artola 2002). The
overall half-life of AHTN in a river water die-away test (Schaefer et
al. 2007) was shown to be 200 hours and the biological degradation after
28 days was 42%. With 10 mg suspended solids from activated sludge, the
conditions in the river die-away test simulate the situation after
release of test substance in effluent into river with respect to the
concentration and origin of suspended solids in the receiving river. The
sediment downstream of a STP is formed by settlement of suspended solids
that will originate at least partly from the solids discharged with the
effluent (30 mg/L). Therefore the conditions are environmentally
relevant but do not correspond exactly with standard biodegradation
simulation tests in surface water, where an amendment with sediment from
the same site is allowed, but not with suspended solids derived directly
from an STP.
et al. (2001) observed that during the degradation process over time
three different metabolites were formed with an increasing polarity with
log Kow going down from 3.9 to circa 0.5. This observation was confirmed
in later studies by Schaefer and Koper (2007).
available monitoring data from sludge, surface water, suspended matter
and sediment provide evidence that AHTN degrades in the aquatic
compartment. Measured concentrations in these compartments have been
decreasing over time and follow hence the diminishing use volume. It
must be noted, however, that no monitoring data on metabolites have been
available mesocosm scale soil dissipation study of DiFrancesco et al.
(2004) resulted in a very slow disappearance of AHTN as 42 to 61 % of
the initial concentration was left in soil after one year (including 3
months of frost). Opposite results have been gained in the large German
study (LfU-BW, 2003) measuring disappearance of AHTN and HHCB over
several years in 13 field locations, where the substances had been
applied with STP sludge to soil. On the basis of this study, the test
item is not expected to have long residence time in soils. The study
does not distinguish between different dissipation routes and
volatilisation may have caused part of the disappearance. However, the
test item is fast degraded in air by indirect photochemical reaction
with OH –molecules and hence the part volatilised is not distributed
Conclusion on P-criterion
On the basis of these data, the TC NES
Subgroup on Identification of PBT and vPvB substances concluded that the
test item does not meet the P-criterion:
· Evidence of inherent
biodegradability from tests with activated sludge is available. Rapid
primary biodegradation was observed and polar metabolites were readily
formed. In an activated sludge die-away test a primary degradation
half-life of 12-24 h was found and in a CAS test 42.5 % of parent
compound was degraded to its metabolites. In a river water die-away test
42% was degraded after 28 days. Mineralization was negligible, but the
formation of metabolites was observed with an increasing polarity
resulting in metabolites showing log Kow from 3.9 to circa 0.5.
· Since 1995 the use volume in the EU
was reduced by a factor of 2. Monitoring data show a decreasing trend of
concentrations in sludge, water, suspended matter, biota and sediment
which is evidence that the test item degrades in the aquatic
· A study investigating the residence
of the test item in 13 soils with different histories of sludge
application showed that the substance had disappeared almost completely
regardless of the time elapsed since the last sludge application.
Volatilisation may have contributed to the disappearance but this
distribution route is not considered relevant, because the test item is
rapidly degraded in the atmosphere.
Confidential report to IFF and PFW,
Fragrance ingredients in STPs and sediment in Berlin. Available on
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