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EC number: 915-730-3
CAS number: -
Abiotic degradation: DT50 in water and air are > 1 year and < 2
Ready biodegradability: The substance is not readily biodegradable.
Activated sludge simulation test: equivalent to OECD TG 303A: In
effluent the substance transformes into polar metabolites for 96% (log
Kow < 2.1) including CO2 formation and uptake in biomass;
Simulation test in river water, equivalent to OECD TG 314: DT50 is < 1
day at 20oC and < 1.9 days at 12oC;
Simulation test in river sediment, equivalent OECD TG 308: DT50 is 9.5
days at 22oC and 17.4 days at 12oC;
Simulation test in soil, equivalent OECD TG 307: DT50 is 6 days at 22oC
and 11 days at 12oC.
Bioaccumulation: Log BCF in fish: 2.6 in an OECD TG 305 study.
Environmental fate and distribution: Log Koc: 4.1; Henry
coefficient: 11.3 Pa.m3/m3 (25oC)
- Abiotic degradation:
Air: Based on a study conducted by Aschmann et al. (2001),
OTNE undergoes in air rapid degradation after reaction with hydroxyl
radicals and NO3 radicals. The atmospheric DT50 value after reaction
with hydroxyl radicals and NO3 radicals is 1 hour and 1.4 minutes
respectively. The half-life time of the substance is < 2 days. The
substance will not reach the stratosphere and is therefore not
considered to be a long-range transported chemical in air (http:
The substance does not have an ozone depletion potential because
it does not contain halogens and does not have the potential to reach
the stratosphere (EU CLP (EC 1272/2008 and its amendments).
Water: It can be reliably predicted that it is
hydrolytically stable. It does not contain hydrolysable groups in its
chemical structure such as esters, carbamates, epoxides, halomethanes,
acylhalides (see Hydrowin, EpiSuite for all hydrolysable groups). The
half-life at 20°C is therefore expected to be > 1 year.
- Biotic degradation:
In the key screening study according to OECD TG 301C 11%
biodegradation (based on analysed material concentration) was found
after 28 days. This study shows that the substance is not readily
biodegradable under the conditions of this test. This result is
supported by an additional ready biodegradability test and an inherent
Die-away studies were carried out with radio-labelled C14 -OTNE in
river water, in sediment as well as in soils. All tests confirm that
OTNE degrades rapidly and that metabolites are formed that are
transformed to polar metabolites and to CO2.
In an activated sludge simulation test (similar to OECD TG
303A by Schaefer and Cartee at Wildlife sponsored by RIFM, 2009) it was
found that during steady state 96% of the substance in the effluent was
transformed into more polar products including CO2 and uptake in
biomass. These polar products had log Kow <2.1 (excluding one metabolite
with similar Log Kow >2.1<6.5). In the whole system 89.72% of the parent
OTNE was removed due to metabolite conversion, mineralisation, volatile
loss and loss due to sorption to solids.
The river water test mimics the conditions in the mixing
zone after the STP and is equivalent to OECD TG 314 (Schaefer, at
Wildlife sponsored by RIFM, 2006). After 28 days 10% mineralisation to
CO2 was detected. The DT50 for primary degradation is < 1 days at 20
+/-3oC. The kinetic assessment showed an initial first-order loss rate
of 1.83/h and a second first-order loss rate of 0.022/h. The converted
DT50 at 12oC is < 1.9 days.
In a sediment study, equivalent to OECD TG 308 (Envirogen
sponsored by IFF, 1999) circa 50% was recovered as CO2 after 8 weeks and
< 1% remained of the parent material. The half-life of the parent
substance was estimated to be 9.5 days at 22oC. The converted DT50 at
12oC is 17.4 days.
In agricultural soil study, equivalent to OECD TG 307
(Envirogen, sponsored by IFF, 1999), the substance is almost completely
degraded after 6 weeks. After 6 weeks the mineralisation (CO2 evolution)
is circa 50%. After a lag time of approx. 7 days the initial rate of CO2
production was 1.4 - 1.8% /day in the sludge amended soil and in the
agricultural soil, respectively. The half-life of the parent substance
was estimated to be 4.2 and 6 days in the sludge amended soil and in the
agricultural soil, respectively, at 22oC. The converted DT50 for
agricultural soil at 12oC is 11 days.
Overall Conclusion on simulation tests: OTNE will be
rapidly biodegraded in more polar compounds including CO2 under natural
conditions in activated sludge, river water, in sediment as well as in
soils, with half-life time of 1.9 day in water, 17.4 days in sediment
and 7.7 days in soil when converted to 12oC.
- Environmental fate and distribution:
Adsorption/Desorption: The substance is a lipophilic
substance with log Kow 5.65. The sorption to organic matter, log Koc,
has been determined using measurements in samples of sludge and effluent
in sewage treatment plants in southern and northern Europe and is 4.12.
This indicates that the substance will have a moderate potential to
adsorb to sediment/soil.
Volatility: To assess the volatilisation potential of the
substance a Henry's law constant was calculated using EUSES, which gave
a result of 23.6 Pa. m3/mol at 25°C and 11.3 Pa. m3/mol at environmental
temperature (12°C). From the distribution modelling
results it can be concluded that volatilisation is of some importance in
the environmental behaviour of the substance.
Bioaccumulation: The BCF value for fish (lipid content 5%)
was determined to be 391. It can be concluded that the substance has a
relatively low bioaccumulation potential.
The BCF in earthworms was estimated to be 5361 l/kg ww with the
equation from EUSES (Jager, 1998), indicating that the potential for
bioaccumulation in terrestrial organisms will be moderate.
BCF for air-breathing organisms: Using the criteria in the PBT
guidance on air breathing organisms (2017) OTNE fulfils these: log Kow
(5.6: > 2) and log Koa (6.9: > 5). The concern for air-breathing
organisms is relevant for non-metabolising substances, which are not
excreted via kidneys and for which the ventilation rate between air and
blood is lower than for fish. This type of bioaccumulation is not
relevant for metabolizing substances as Gobas et al. explicitly mentions
(2020, figure 6, D, assessing oxygen containing substances). OTNE is an
oxygen (ketone) substance with a hydrocarbon unsaturated backbone with
two-ring structures. The ketone is expected to be reduced to an alcohol
because glucuronidation is the key excretion pathway and this acid can
only conjugate with an alcohol bond (see toxico-kinetic section). This
transformation is expected to occur in all (air-breathing) organisms.
Glucuronic acid has a low log Kow (<-1) and also OTNE-glucuronidated
will have the acidic group and therefore this log Kow < -1. This results
in excretion via kidneys as can be seen in the repeated dose-toxicity
studies. In addition, the half-life in fish in the BCF test is 1.2 days.
In mammals (rat) the DT50 was 1.4 days after oral doses of 20 mg/kg bw
showing absence of bioaccumulating in fish and in air-breathing
organisms. This means that OTNE and its degradants or metabolites are
not a concern for air-breathing organisms.
Based on Level III distribution modelling using EPISUITE (assuming
equal and continuous releases to air, water and soil) using the CAS
number 54464-57-2 and the measured physico-chemical parameters as input,
it is estimated that the majority of the substance released to the
environment will partition mainly into soil (89.1%) with smaller amounts
to water (8.84%) and sediment (2.08%) and a negligible amount to air
The SimpleTreat model, which is incorporated in EUSES, simulated
the distribution of the substance in a Sewage Treatment Plant based on
vapour pressure, water solubility, log Koc and biodegradability. The
model predicts that 0% of the substance will biodegrade, 37.2% of the
substance will partition to water, 56.8% to sewage sludge and 6.03% to
air at 12°C.
Experimental simulation data show that the removal from the STP
ranges from >50% to far more than 90%.
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