Addendum for Trifluralin
Second Draft
Prepared by BiPRO GmbH
March 2010
Adjusted: April 2010
Table of Content
1
Introduction ................................................................................................................................... 2
2
Assessment of new information provided by Canada ....................................................................... 3
2.1Summary of the information provided by Canada on Bioaccumulation ................................. 3
2.2Comments on the information provided by Canada on Bioaccumulation .............................. 4
2.3Summary of the information provided by Canada on criterion 2b ....................................... 10
2.4Comments on the information provided by Canada on criterion 2b .................................... 11
3
Additional information on environmental occurrence/monitoring ..................................................12
4
Transformation products of trifluralin ............................................................................................17
5
References ....................................................................................................................................21
1
1
Introduction
In accordance with Article 14 of the UNECE POP protocol the European Community and its Member States
have proposed trifluralin to be added to the Protocol. The TFPOP in its seventh meeting in June 2009 agreed
that this substance fulfils the POP criteria. The European Commission hence has the lead to develop a risk
management option dossier for trifluralin for consideration in the next UNECE task force meeting. However,
some concerns have been raised as regards certain aspects of the trifluralin dossier during the TFPOP
meeting in June 2009. Canada provided additional information on trifluralin in December 2009 for
consideration of the review of the substance.
This report is an addendum to the Trifluralin Dossier prepared in support of the EC nomination proposal of
trifluralin [EC 2007].
To ensure that the POP dossier on trifluralin contains the latest relevant information on its POP
characteristics and its metabolites, this addendum includes an assessment on the additional information
submitted by Canada (Chapter 2), an update on the available literature (Chapter 3) and a limited assessment
of the POPs characteristics of the most important degradation/biotransformation products of trifluralin
(Chapter 4).
2
2
Assessment of new information provided by Canada
The information provided by Canada in December 2009 included additional information for consideration in
the interpretation of the bioaccumulation criterion and the adverse human health and/or environmental
effects as a result of its long-range transboundary atmospheric transport.
2.1
Summary of the information provided by Canada on Bioaccumulation
BCF and BAF values
The authors of the Canadian comments summarise that reported and reviewed laboratory BCF and BAF
values of trifluralin ranged from 276-4730 in algae, 20 - 870 in snails, 30 - 92 in daphnia, to 8893-8870 in
various fish species. It was highlighted that there is considerable variability in BCF values between studies,
within studies and within species suggesting that the evidence of trifluralin for bioaccumulation is conflicting.
It is concluded that some studies stress that this substance exceeds the numeric criterion for
bioaccumulation. However, many of these studies also show that trifluralin is readily depurated.
Elimination of trifluralin
Various studies addressing the depuration half-lives for different aquatic species presented in the paper
indicate half-lives between 2 and 57 days. It is claimed that trifluralin is readily eliminated in fish and other
organisms and that the metabolism profile seen in fish is consistent with the metabolism profile observed in
various terrestrial species. The authors associate studies with terrestrial animals with depuration in aquatic
organisms. Thus, it is highlighted that in studies conducted on rats, trifluralin was shown not to be readily
absorbed from the gastrointestinal tract after oral intake. Essentially all of absorbed trifluralin was
completely metabolised and eliminated within 3 days after oral administration. It is pointed out that
although no robust data on the toxicokinetics of trifluralin in humans have been reported, the Trifluralin
Dossier (EC 2007) indicated “that there is no evidence of bioaccumulation of trifluralin and it does not
appear to have been detected in human adipose tissue, breast milk or in blood samples from the general
population.” It is concluded that this is despite evidence of long range transport of trifluralin and its high
volume of use in North America and other parts of the world for over 40 years.
Bioavailability
It is stated that studies may not adequately represent bioaccumulation dynamics in the natural environment
where it is expected that trifluralin may be primarily adsorbed to sediment. The available data indicate that
the substance is strongly adsorbed to sediments but there is uncertainty whether trifluralin is readily
available for bioaccumulation. According to the additionally provided data, there is evidence in published
studies that toxicity and bioconcentration factors are lower when exposure occurs under realistic conditions
in the presence of sediment in a static system versus when fishes are exposed to an artificial system where
there is a continuous input of trifluralin through the water phase only.
Lack of monitoring data in biota
It is stated that although some BCF values indicate that there is a potential for bioconcentration, there is no
evidence of appreciable levels of trifluralin measured in biota in the field under typical exposure conditions
despite evidence of long range transport of trifluralin and its high volume of use in North America and other
regions for the past 40 years.
3
2.2
Comments on the information provided by Canada on Bioaccumulation
Comments regarding BCF and BAF values
Within the technical Track A review process, all four reviewers, based on the indicative numerical values (BCF
>5000 and log Kow = 5.27), concluded that trifluralin satisfies the LRTAP guidance for bioaccumulation.
Bioaccumulation of trifluralin is evidenced by various studies for different species. With BCF values in the
range 1580-8870 trifluralin is considered to be highly bioaccumulative as highlighted in the UNECE Risk
Profile of Trifluralin, especially for fish [EC 2007].
The Canadian paper presents some additional information with respect to BAF values of zooplankton, oysters
and fish indicating BCF and BAF values below the indicative numerical value.
At first sight, the reported BCF and BCA values for different species seem to be in conflict. Nevertheless, it is
well known, that the calculation of BCA values is influenced by various factors like species of the test animals,
duration and intensity of exposition, way of exposure (solubilised or bound to sediment) water temperature
and much more. Related aspects are also discussed in the following sections when considering depuration of
trifluralin from different species and adsorption of trifluralin to sediment. Therefore it is not astonishing that
there exists information about trifluralin bioconcentration factors well below the numerical indicative value
of 5000 for several species.
BCFs should be independent of the specific waterborne concentrations. This is not the case in several of the
relevant studies, most likely due to the experimental conditions (for example reduced bioavailability at high
concentrations). Low BCFs observed at relatively high exposure concentrations should be disregarded
because they are irrelevant for assessing bioconcentration at much lower environmental concentrations as
they may occur under realistic conditions. Accordingly, the results for BCFs shown in Table 1 indicate
comparatively low BCFs at high exposure levels and vice versa.
There are two GLP studies indicating BCF values above the numeric criterion 5000 (Graper and Rainey
(1988): BCF 5674; Meyerhoff and Gunnoe (1992): BCF 1750 to 8870; see bold lines in Table 1). For the
second study, only the value of 8870 obtained at the lowest tested concentration should be considered
relevant.
Table 1:
Results of bioaccumulation studies with trifluralin in fish (quoted from [OSPAR 2005]).
Species
BCF
whole fish
Lepomis macrochirus
5674*
Lepomis macrochirus
1580**
Lepomis macrochirus
1087-1838*
Pimephales promelas
1750-8870**¯
Test conditions
28 days uptake; FLO;
2μg/l trifluralin; GLP
35 days uptake; FLO; ~8 μg/l
trifluralin; non-GLP***
8 days; STA; 0,5-12,5 mg/kg
trifluralin; non-GLP****
35 days uptake; FLO; 0,3-30
μg/l trifluralin; GLP
Clearance half-life ct₅₀ [d]
Residues after 14d
4,6
< 10%
4,3 - 5,6
Not calculated
Not calculated
Source
Year
[EUTTF 2002]
1996
[EUTTF 2002]
1973
[EUTTF 2002]
1985
[EUTTF 2002]
1990
*calculated from the uptake rate constant.
** calculated from the ration of concentrations in fish and water.
***there are major deviations from the OECD Guideline 205E. therefore, this study is intended to provide supplementary information only.
**** Sediment containing trifluralin was stirred into the test vessels. Concentrations refer to test substance in sediment wet weight. Dissolved
trifluralin was detected at a maximum of 1,9 μg/l, declining to 0,6 μg/l. This nonstandard study is intended to provide supplementary
information only.
¯ The low BCF of 1750 was obtained in the high concentration of trifluralin (30 μg/l) and the high BCF of 8870 was obtained in the low
concentration of trifluralin (0,3 μg/l). STA: static test; FLO: flow-through test; GLP: test conducted under "Good Laboratory Practice".
4
The BCFs that have been determined in GLP studies (i.e. 5674 and 8870) are only slightly above the numeric
value for the bioaccumulation criterion (5000).
Considering also the rapid metabolism/elimination observed in different taxonomic groups, reported values
below the criterion of 5000 can most likely be associated to the experimental conditions and/or physiological
differences, particularly in the case of on non-fish species.
Thus the conclusion should be that the numeric screening criterion of BCF >5000 is fulfilled.
Comments regarding bioavailability
The authors of the Canadian paper indicate some concerns regarding the highest BCF and BAF values for fish
in the field reported by Graper and Rainey (1988) because the high potential of trifluralin to adsorb to the
sediment was not considered in these studies. Such statement could be done for any of the listed POPs as all
of them are highly hydrophobic and therefore are strongly absorbed to sediment and reduce the availability
to be directly uptaken via the water phase. However, direct uptake by sediment or suspended matter should
not be ignored for such hydrophobic compounds as shown for Trifluralin in [Francis and Cocke 1985].
Francis and Cocke (1985) examined the “Bioavailability of Sediment-sorbed Trifluralin to Bluegill Under
Laboratory Conditions”. Mean sediment trifluralin concentrations following aging were 0.5, 2.40 and
11.59 mg/kg. Suspended sediment concentrations immediately after stirring were 0.0070-0.0084,
0.0390-0.0432 and 0.2207-0.2553 mg/L, respectively. At the highest level of sediment treatment and
concentration of sediment in exposure water, dissolved trifluralin was detected at 1.9 µg/L declining to
0.6 µg/L by test termination. Trifluralin was detected in all groups of exposed fish at 0.001-1.606 µg/g above
the background level in control fish (of 0.003 µg/g or less). Tissue levels increased with suspended sediment
load and sediment trifluralin concentration. A model developed to describe the distribution of trifluralin
between the three compartments of the study system used first-order kinetics for trifluralin uptake by fish
and dissipation from the exposure solution, taking into account the effect of suspended sediment on these
factors. The model provided good estimates of the residues measured in exposed fish. Estimated uptake and
depuration rate constants were used to compute steady-state bioconcentration factors in the range
1087-1838 mL/g. It was concluded that Trifluralin was readily bioconcentrated (BCF 1087-1838 mL/g) in
bluegill (Lepomis macrochirus) exposed for eight days to solutions containing 0.01-0.25 g/L of sediment
treated with 0.5-12.5 mg trifluralin/kg. The results of this study clearly indicate that uptake of trifluralin
bound to sediment by aquatic animals (especially animals which inhabit sediment) is likely to occur. The
latter may result from oral uptake of sediment particles carrying trifluralin on their surface or by uptake of
trifluralin dissolving from the sediment particles over the gills [EUTTF 2002].
Regarding the results of The National Lake Fish Tissue Study (US EPA 2009, see chapter on levels of trifluralin
in biota) it should be highlighted that trifluralin occurred in the bottom-dweller samples of 32 % of the sites
and predator samples of 10 % of the sites. Uptake of sediment particles and thus sediment bound trifluralin
is much more likely to occur for bottom-dwellers than for predator fish. This may be the main reason for
more frequent detection of trifluralin residues in bottom-dweller tissues. The differences in uptake between
predator fish and bottom-dwellers clearly indicates that considerable uptake of sediment bound trifluralin
occurs under environmental conditions. Therefore, it cannot be argued that most of the trifluralin released is
bound to sediment and therefore not available for uptake by fish. Consequently it cannot be concluded that
BCF values of trifluralin measured under laboratory conditions are generally disproportionately higher than
respective BCF values determined from field data. Furthermore, it was criticized that the study of Spacie and
Hamelink (1979) reporting a BAF value of 6000 was conducted downstream of a manufacturing plant, which
5
might not be typical of exposure conditions compared with concentration and timing of exposure resulting
from agriculture uses or in remote areas. Spacie and Hamelink (1979) when calculating the BCF values for the
period before water treatment determined the average concentration of trifluralin in water to be 1.8 µg/L.
Exposure concentrations in other field studies and laboratory studies listed in Annex A of the Canadian paper
seem to be in a comparable range (e.g. 5.9 µg/L Graper and Rainey (1988), 20 µg/L Slieght (1973), 2 µg/L
Schultz and Hayton (1994)). The Canadian authors point out that the BCF values determined for larger
species (e.g. sauger) in the study of Spacie and Hamelink (1979) were not reflective for steady state
conditions because the fish burdens were not yet at equibrilium. However, Spacie and Hamelink (1979) used
the measured residues in fish and water to calculate a concentration ratio K defined as residue concentration
in mg/kg of body weight devided by concentration in water (mg/L). They note that under steady-state
conditions, when the body residues are equilibrated with respect to uptake and clearance, this K ratio is
equal to the bioconcentration factor (BCF). The derived BCF values for sauger, (5800) shorthead redhorse
(2800) and golden redhorse (1800) were calculated from trifluralin concentrations measured before carbon
treatment of waste water. At that time the fish had been exposed to trifluralin over a long period and
concentration levels are well equilibrated with respect to uptake and clearance (i.e. steady state conditions)
This is explicitly mentioned in the paper. (source [Spacie and Hamelink 1979]).
Comments related to elimination of trifluralin
Reported depuration half-life values for fish between 2 days to 57 days are reported in the Canadian
document. Similar values are reported for existing POPs or POPs candidates (see table below). The
Preliminary guidance paper on bioaccumulation evaluation, depuration half-life is not used to demonstrate
the lack of bioaccumulation, but can be used, in case of long half-life, as an additional argument to confirm
bioaccumulation potential of a substance in particular where BCF is below the cut-off value
(UNEP/POPS/POPRC.3/20)
6
In a study of Han et al. (2007), values of intrinsic clearance (CLint) of seven reference compounds1 in
hepatocytes freshly isolated from rainbow trout and rat were determined using a substrate depletion
approach. Trifluralin was metabolised in rat hepatocytes with a CLint value of 2.15 ±0.56 mL/h/ 106 cells,
whereas in trout hepatocytes, the clearance rate was estimated to be 0.027± 0.016 mL/h/106 cells. CLint for
all compounds were 5.5-78.5-fold lower in trout hepatocytes than those in rat hepatocytes. Trifluralin was
the substance with the lowest clearance rate in rainbow trout (78.5 fold lower compared to rat). This clearly
indicates that even if the metabolism profile of trifluralin in terrestrial animals and fish may be comparable,
the elimination rates are quite different [Han et al. 2007]. The results of Han et al. (2007) illustrate that the
elimination rate of trifluralin in terrestrial animals might be significantly higher than in aquatic animals.
Guerrero et al. (2002) performed acute static bioassays using the three freshwater invertebrate species
(oligochaete Lumbriculus variegatus, fingernail clam Sphaerium corneum and the larvae Chironomus
riparius). The organisms were exposed separately to 14C radiolabelled Trifluralin to investigate if trifluralin
remained as parent compound after the treatments. Homogenates of the whole body tissue of each
organism were prepared and total radioactivity was measured. Contaminants were then extracted into
organic solvents and analysed by high-pressure liquid chromatography techniques. For S. corneum and C.
riparius, the concentrations accumulated were quite similar (taken from the presented figures approximately
3nmol/g wet tissue). Instead Lumbriculus variegatus presented the highest levels of uptake for trifluralin
analysed (taken from the presented figures approximately 12 nmol/g wet tissue). Since the soft tissues of
clams, worms and midges were roughly the same weight, differences on uptake could not be attributed to
1
atrazine, molinate, 4,4-bis(dimethylamino)- benzophenone, 4-nonylphenol, 2,4-di-tert-butylphenol, trifluralin,
benzo(a)pyrene
7
the size of the organisms. Chromatograms showed that most of the trifluralin extracted was present as
parent compound in S. corneum and in L. variegatus. In contrast, for C. riparius the recovery of trifluralin as
parent compound represented a 17.5% of the total radioactivity of the homogenate. The chromatograms
showed the presence of two additional peaks [Guerrero et al. 2002].
These results suggest that different metabolic processes could take place in the different species resulting in
different uptake and metabolism and bioaccumulation rates. Therefore, it is unlikely that trifluralin is
metabolised and depurated equally effective by all aquatic organisms and as a consequence it cannot be
concluded that bioaccumulation of trifluralin in aquatic biota is unlikely to occur under natural conditions. If
specific differences between aquatic organisms result in high levels of accumulation, these metabolic
differences may result in biomagnification processes in their predators [Guerrero et al. 2002].
According to Kelly et al. (2007) poorly metabolisable, moderately hydrophobic substances (i.e., Kow between
100 and 100,000), which do not biomagnify in aquatic food webs, can biomagnify to a high degree in food
webs containing air breathing animals (e.g., humans , marine mammals) if they have a high octanol-air
partition coefficient and corresponding low rate of respiratory elimination to air. This is the case for
trifluralin. Under the assumption, that no metabolic transformation occurred, calculated biomagnification
factors for trifluralin for water respiring organisms are below 1 (for zooplankton, forage fish and predatory
fish) whereas they range from 2.8 to 34 for air breathing organisms (reptile 6.2, amphibian 11, seabird 12,
marine mammal 26, terrestrial herbivore 2.8, terrestrial carnivore 34, human 28) [Kelly et al. 2007]. These
findings indicate that trifluralin has the potential to biomagnify in terrestrial food webs and in air breathing
organisms of the marine mammalian food web. However, under environmental conditions, metabolic
transformation needs to be taken into account and will be a key issue for assessing a realistic
bioaccumulation potential of trifluralin.
When discussing the bioavailability of trifluralin, the non-extractable residues (NER) formation in soil or
sediment needs to be taken into account. An observed disappearance of a compound does not necessarily
mean that the compound has been degraded. In an open system the compound may have been transferred
to another compartment (e.g. from water to sediment). In a closed system non-extractable residues may
have formed and the observed disappearance is a combined effect of NER formation and actual degradation.
The formation of NERs can often be observed in biodegradation studies with soil or sediment. The NERs are
defined as the fraction of the original test substance (and metabolites) that is not degraded and not
recovered via exhaustive sequential extraction of the solid matrix. A relevant question is whether NERs are
still bioavailable or may become again bioavailable. The two extreme viewpoints in this debate are (1) either,
according to the precautionary principle, to consider all NERs bioavailable as long as scientific findings are
inconclusive or (2) conversely, to consider all NERs not bioavailable( [Boething et al. 2009]). According to a
recent water-sediment study for trifluralin the NERs amount to 77 % applied radioactivity (AR) associated
with the humin fraction [EFSA 2009]. As a consequence, for substances such as trifluralin with a high rate of
NERs formation, low levels of the compound detected in the environment do not allow to simply conclude
on low bioavailability of the compound (see also chapter 4).
Monitoring data in biota and mammals
The National Lake Fish Tissue Study is the first national freshwater fish tissue survey to be based on a
probabilistic sampling design, and it includes data on the largest set of PBT chemicals ever studied in fish.
8
EPA worked with partner agencies in states, tribes, and other federal organizations over a four-year period
(2000–2003) to collect fish from 500 lakes and reservoirs in the conterminous USA. The information provided
in the report documents the national distribution of 268 PBT chemicals in predator fish species (e.g., bass
and trout) and in bottom-dwelling fish species (e.g., carp and catfish) from lakes and reservoirs in the USA.
Trifluralin occurred in the bottom-dweller samples of 32 % of the sites and predator samples of 10 % of the
sites.
Table 2: Results from the National Lake Fish Tissue Study. MDL: method detection limit; ML: minimum
level [U.S. EPA 2009].
Tissue Concentration Estimates for Predators (Fillets)
ppb
< MDL
< MDL
< MDL
< MDL
< MDL
< MDL
95 th
Percentile
11
90 th
Percentile
36
75 th
Percentile
486
50 th
Percentile
Units
25 th
Percentile
Maximum
Conc.
10 th
Percentile
Number of
Detects
5 th
Percentile
Number of
Samples
3.16
< MDL
< MDL
3.76
7.26
13.88
Tissue Concentration Estimates for Bottom Dweller (Whole Bodies)
395
144
96
ppb
< MDL
< MDL
Results for Predators
MDL μg/kg (ppb)
ML μg/kg (ppb)
< MDL
≥ MDL & < ML
≥ ML
Total
2.98
10.0
450
35
1
486
10.0
251
84
60
395
Results for Bottom Dweller
2.98
A field monitoring study on fish was cited in the draft assessment report on trifluralin. The study was
designed to measure trifluralin residues in fish and benthic invertebrates, to perform radiological
examinations on fish and to monitor the concentrations of trifluralin in water, sediment and field run-off. The
results of the study demonstrated that trifluralin can accumulate to detectable levels in fish inhabiting ponds
that receive run-off from fields treated with trifluralin. Furthermore, the data from the study confirmed that
actual residue levels, although typically increasing after run-off events, are low under environmental
conditions. The maximum whole body residue level measured in fish during the entire study was 0.290 µg/g,
which is approximately one order of magnitude lower than the residues found in fish continuously exposed
to the chronic NOEC of 0.3 g/L for 35 days [Francis et al. 1985].
The authors of the Canadian comments highlight that the Trifluralin Dossier [EC 2007] indicated that
trifluralin does not appear to have been detected in human tissue, breast milk or blood despite evidence of
long range transport and high volume use in North America for over 40 years. Barr et al., 2010 evaluated in
utero exposures to pesticides by measuring maternal and cord serum biomarkers in a New Jersey cohort of
pregnant women and the birth outcomes of their neonates. The study was based on 150 women that
underwent an elective cesarean delivery at term in a hospital in central New Jersey. The frequencies of
detection of trifluralin were 68 % in maternal serum and 25 % in cord serum samples. The agreement
between maternal and cord sera detection was significant for trifluralin (p<0.001). Generally, if a pesticide
was detected in maternal serum, it was also found in the corresponding cord serum indicating transfer of
some portion of the maternal dose to the fetus. Mean maternal serum concentrations are summarized in
Table 3 [Barr et al. 2010]. The results of this study indicate that uptake of trifluralin to humans occurs due to
9
environmental exposure and contact with pesticide residues whether from dietary, non-dietary ingestion,
residential, or occupational pathways . Therefore, the lack of data regarding trifluralin residues in human
tissues and blood may not simply result from the absence of detects as supposed by the Canadian authors. In
fact, there exists an information gap regarding monitoring data of trifluralin in humans and biota from use
areas and remote areas.
Table 3:
Mean maternal serum concentrations of trifluralin in a population of pregnant women and
newborns in New Jersey (source [Barr et al. 2010])
Number of samples with detectable
pesticide level
Mean (SD) (ng/g)
Minimum / maximum
Maternal serum
138
0.75 (1.37)
0.00 / 8.50
Cord serum
148
2.16 (1.54)
0.007 / 4.42
Sample
It can be concluded that information on appreciable levels in fish and humans is available. However, the
information is very limited.
Conclusion on bioaccumulation
The numerical criterion for bioaccumulation according to BCF values can be considered fulfilled. However,
the assessment of the potential for bioaccumulation under environment conditions is related to specific
knowledge gaps.
It is difficult to simulate realistic environmental conditions in laboratory studies and to investigate the uptake
of sediment associated trifluralin. However, also laboratory studies provide indications that trifluralin
adsorbed to sediment is available for uptake by aquatic organisms (e.g. Francis and Cocke (1985)).
The potential for bioaccumulation under environment conditions depends largely on the elimination rates in
biota and the environment. Even if the metabolism profile of trifluralin in terrestrial animals and fish may be
comparable, the elimination rates are quite different [Han et al. 2007]. The elimination rate of trifluralin in
terrestrial animals might be significantly higher than in aquatic animals. Furthermore, it is unlikely that
trifluralin is metabolised and depurated equally effective by all aquatic organisms (see [Guerrero et al.
2002]). Trifluralin has in theory the potential to biomagnify in terrestrial food webs and in air breathing
organisms of the marine mammalian food web. BCF values for fish are inappropriate indicators for the
biomagnification potential in air breathing animals. The bioaccumulation potential depends largely on the
species dependent elimination rates.
Available data indicate that trifluralin can accumulate to detectable levels in fish and benthic invertebrates
[Francis et al. 1985] and is stronger accumulated by sediment living aquatic organisms than by organisms
living in the water body (see [U.S. EPA 2009]. Information on elimination rates indicates that the elimination
rate of trifluralin in terrestrial animals might be significantly higher than in aquatic animals. The formation of
NERs should also be considered when studying elimination rates of trifluralin.
2.3
Summary of the information provided by Canada on criterion 2b
The Canadian authors highlight that based on the existing data, it does appear that there is transport to
10
remote areas, likely primarily via adsorption to particles. Furthermore, it is stated that once in a remote
location, it seems unlikely that such adsorbed material is readily bioavailable. When entering the aquatic
environment, trifluralin will migrate quickly from water and adsorbs strongly to sediment thereby reducing
the availability for uptake. Toxicity endpoints are significantly higher (i.e. less toxic) and bioconcentration
factors are significantly lower in systems including sediment bound residues versus those systems with
continual influx of trifluralin residues in the water column. This, coupled with the known high rate of
elimination, suggests that the lack of trifluralin (both detections and low concentrations) in biota is likely
related to chemical dynamics and exposure metrics.
2.4
Comments on the information provided by Canada on criterion 2b
As outlined above, sediment associated trifluralin may be readily bioavailable and information on elimination
rates of trifluralin indicates high species dependency. Monitoring data on levels of trifluralin in relevant
species and humans are limited for remote areas. Such information could enable to assess possible adverse
effects due to long range transport of trifluralin.
11
3
Additional information on environmental occurrence/monitoring
Arctic
Trifluralin has been measured in air at three Arctic monitoring stations (Tagish: 2.92 pg/m3, Alert: 0.64 pg/m3,
Dunai: 0.13 pg/m3). According to half-life calculations based on photochemical degradation, detectable
quantities of trifluralin should not reach the Arctic at measurable quantities even though relatively large
amounts (>5 x 106 kg) are applied annually to crops in western Canada and the USA. Other pathways
(transport on dry particulate or aerosol) might be probable transport forms (quoted from [EC 2007]).
Trifluralin was sporadically found in samples from Nuuk collected in winter and autumn with an annual
average concentration of 0.24 ± 0.22 pg/m3. Further information is listed in Table 1. [AMAP 2005]
Table 4:
Annual mean, median, minimum and maximum concentrations values of trifluralin [pg/m³] in
Nuuk. The d/n column indicates number of detected concentrations. [AMAP 2005]
Substance
d/n
Mean
Median
Min
Max
Trifluralin
4/13
0.2
0.2
0.0
0.6
Literature on current use pesticides (CUPs) in arctic media has been reviewed from 2000 to 2007 by
Hoferkamp et al. (2009). The following summary is quoted from their review. Welch et al. (1991) reported
trifluralin in snow from the Canadian arctic. The snow was associated with a “brown snow” event whose clay
mineral composition, soot particles, and visible organic remains point to an Asian source, probably western
China. Melted snow samples were found to contain trifluralin at 0.660 ng/L [Welch et al. 1991].
Methoxychlor and trifluralin were detected in air sampled at stations in the Canadian Arctic (Halsall et al.,
1998; Hung et al., 2002) while trifluralin, chlorpyrifos and chlorothalonil were identified in surface water, ice
and fog samples from the Bering and Chukchi Seas (Chernyak et al., 1996). Studies of Arctic air masses
sampled at stations in the Canadian, Alaskan, Russian and Norwegian Arctic between 2000 and 2003 included
direct measurements of the CUPs methoxychlor and trifluralin (Su et al., 2008). Positive results for air
concentrations of these CUPs were noted but the levels were below analytical detection limits and thus
values not specified. In an earlier report Hung et al. (2005) reported annual average levels of trifluralin in air
approaching the practical quantitation limit (PQL); 0.13–0.18 pg/m3 at Tagish, 0.1–0.05 pg/m3 at Kinngait
and 0.18–0.16 pg/m3 at Dunai. Muir et al. (2007) analyzed large volume water samples from Lake Hazen in
northern Ellesmere Island and from Char Lake on Cornwallis Island, collected in 2005 and 2006. Trifluralin
was among the CUPs detected in all samples at low pg/L concentrations. Evenset et al. (2004) report finding
trifluralin and lindane residues in sediments, collected in 1996 from two lake sites on Bjornoya Island in the
Barents Sea. Lake sediments showed levels of trifluralin that were at the PQL (0.04 ng/g dw). Evenset et al.
(2004) report finding trifluralin and lindane in zooplankton and Arctic Char collected in 1996 from two lake
sites on Bjornoya Island in the Barents Sea. However, trifluralin was below the limit of quantification and
actual concentrations were not reported. In the opinion of Hoferkamp et al., the question whether the
presence of current use pesticides at low levels in arctic ecosystems has any significance biologically or
results in risks for human consumers is a question that has not been adequately addressed. In their
conclusion they point out that UNECE dossiers for the pesticides trifluralin, PCP and dicofol have not
addressed this issue for human or wildlife exposure in remote environments generally(source [Hoferkamp et
al. 2009]).
12
Bossi et al. (2008) report atmospheric concentrations of trifluralin in arctic air. Sampling was carried out in
Nuuk during 2004 and 2005. The annual average concentration of trifluralin in Nuuk was 0.09 to 0.19 pgm3.
Trifluralin was only detected in samples collected in winter and autumn. Model calculations were performed
in order to correlate temperature and anthropogenic CO to atmospheric concentrations. The model
calculations showed that the predominant anthropogenic sources for CO in Nuuk are located in North
America. The results showed a clear correlation with CO for trifluralin, indicating an anthropogenic origin of
trifluralin from current use [Bossi et al. 2008].
Marine waters
A few trifluralin findings in the North Sea (0.002-0.02 ng/l) and the Baltic Sea (0.0-0.06 ng/l) have been
reported by the German Marine Environmental Database (Meeres-Umweltdatenbank, MUDAB) between
1997 and 1999. Details on sampling locations and analytical methods are presently not available. The
reported values are below the limit of detection reported for findings in freshwater. Data from marine
sediment is not available [Hillenbrandt et al. 2006].
The German Bundesamt für Seeschifffahrt und Hydrographie (BSH) reported that trifluralin concentrations in
North Sea water (area of the German Bight and the Elbe-Estuary) as well as water from the German Baltic
Coast did not exceed the detection limit (< 0.03 ng/l and < 0.005 ng/l, respectively) between 1999 and 2002.
[OSPAR, 2005]
Chernyak et al. (1996) discovered trifluralin concentrations of about 1150 pg/l (detection limit 10 pg/l) in the
water surface microlayer in the Bering and the Chukchi Seas (North Pacific) in 1993, which may arise from
marine fog since trifluralin has been found therein. Concentrations of trifluralin in samples of subsurface
water and ice were below the detection limit (0.5 and 2 pg/l, respectively)..
Europe
The European Commission focused on the prioritisation of substances potentially hazardous for the aquatic
environment (Water Framework Directive 2000/60/EC) and therefore applied a combined monitoring and
modeling based setting (COMMPS) working with monitoring data collected from different rivers in Europe.
(http://europa.eu.int/comm/environment/water/water-dangersub/commps_report.pdf).
Trifluralin was detected in 819 from 12,800 surface water samples at 752 sampling stations from Austria,
Belgium, France, Germany, UK and Italy. Many measurements resulted in findings below the determination
limit (0.005-0.2 μg/l), but positive findings of trifluralin and according to COMMPS trifluralin is to be expected
due to regular uses (90th percentile concentration: 0.0306 μg/l). Means for trifluralin are in the range of the
German quality standard for trifluralin in surface waters with respect to aquatic biocoenoses (0.03 μg/l). The
90-percentile value of 0.0306 μg/l is lower than the drinking water threshold concentration for individual
plant protection products (0.1 μg/l) [OSPAR, 2005].
According to the shared database of Länderarbeitsgemeinschaft Wasser (LAWA) and the German Federal
Environmental Agency [UBA 2005] water samples of German flowing waters were analysed for trifluralin in
187 series of measurements between 2002 and 2004. Within 30 test series the mean value measured was <
0.05 μg/l, 5 test series had a mean value < 0.06 μg/l and 15 test series had a mean value < 0.1 μg/l.
Another survey focusing on occurrence of trifluralin in surface water, drinking water and other water as well
as ground water sources was undertaken by Dow AgroSciences in EU 15 including Norway and Switzerland.
Tables 4 and 5 give an overview on the results of the monitoring data (source: [OSPAR 2005]).
13
Table 5:
Summary of trifluralin monitoring data in surface water, drinking water and others (unpublished survey
report by producer Dow AgroSciences). Notes: LoD: limit of detection (LoDtm: limit of determination), ©:
Data ex COMMPS database, *: Where there was a risk of multiple reference (e.g. COMMPS and national
data) sites or samples have not been added in the total count, i.e. the total sample number represents the
minimum number, **: 95th percentile; ***: One value at 8.3 mg/l (must be due to isolated pollution
incident), n.d.: no data available. (source: [OSPAR 2005])
Country
Surface water
Austria ©
Belgium
Belgium ©
France
Date
No.
sites
No.
Samples
Detected (samples)
Samples >0.1 µg/l
No.
%
No.
%
0
87
12 sites
21
1
5 sites
0
0
1
7
>6.8
16.4
0.3
>3
0.1
0
1
0
n.d.
n.d.
>1
0
0
0
0.08
--
3.2
0.070.3
0.03
0.04
0.06
Max
LoD
(LoDtm)
µg/l
Cat
I
I
I
I
III
I
I
II
I
0.05
0.36
0.036
n.d.
0.045
n.d.
n.d.
n.d.
(0.02)
n.d.
0.03-0.05
<0.1n.d.
0.01-0.1
(0.005-0.2)
n.d.
0.005
0.05
0.05-0.1
0.01
n.d.
0.002**
0.27***
0.005
0.0050.7
0.22
n.d.
0.005-0.01
0.005-1.0
0.005-0.08
0.005-0.2
0.005-0.05
0.005-0.2
(0.005-0.2)
n.d.
II
II
I
I
I
I
I-III
0.01-0.1
(0.01-0.1)
0.02
0.002
0.01
0.002-0.01
(0.01-0.1)
I
µg/l
1998
96-99
1997
1996
1997
1996
1992
91-93
93-94
2
n.d.
33
n.d. 38
37
n.d.
5
44
6
1281
177
128
304
165
n.d.
147
936
1996
92-93
1997
95-97
91-92
92-94
9
7
2
12
3
n.d.
122
63
2
150
56
n.d.
1
6
0
0
4
n.d.
0.8
9.5
7.1
-
0
2
0
0
0
n.d.
1995
1999
92-95
1996
1997
1998
91-99
n.d.
729
7
5
5
7
870
3264
4888
>19
72
68
104
11651
98
214
0
1
0
0
437
3
4.4
1.4
3.8
1
2
0
0
0
0
7
96-98
83
472
18 sites
>3.8
(22%
sites)
1-5 sites
0.2-1
(1-6%
sites)
Drinking water
Germany
93-94
166
1092
0
-
0
-
-
Ireland
Netherlands
UK
Total*
95-96
1992
94-96
92-96
50
7
59
282
50
7
5228
6377
0
0
1
1
0.02
0.02
0
0
1
1
0.02
0.02
>0.1
>0.1
42
255
3
1.3
0
-
0.01
0.0005
II
4682
30575
449
1.5
9
0.03
0.7***
0.0005-0.2
(0.005-0.2)
I-III
France ©
Germany
Germany ©
Greece
Italy ©
Switzerland
UK
River Rhine
(CH D NL)
Total*
EU-COMMPS
(A B D F I)
Unspecified waters
Greece
95-97
All water types
Total*
90-99
14
>0.6
-
0.7
0.09
n.d.
n.d.
0.22
0.05
I
I
I
III
III
II
I
I
II
III
I-III
Table 6:
Summary of trifluralin monitoring data in ground water (unpublished survey report by producer Dow
AgroSciences). Note: LoD: limit of detection (LoDtm: limit of determination), *: determination of the limit of
detection is uncertain, **: where there was a risk of multiple reference (e.g. COMMPS and national data)
sites or samples have not been added in the total count, i.e. the total sample number represents the
minimum number. (source: [OSPAR 2005])
Country
Date
No.
sites
No.
samples
Austria
92-97
7000
No.
1
%
0.01
1997
90-93 9394
170580
56
20
344 2
336
100
2114
1
0
0
0.3
-
?
0
0
1997
1996
1992
1999
90-99
146
>1
7
334
3 488
2146
72
7
517
>12292
0
0
0
6
8
1.2
<0.06
0
0
0
0
1
France
Germany
Switzerland
Netherlands
UK
Total**
Detected (samples)
Samples
>0.1 µg/l
No.
%
1
0.01
Max.
LoD (LoDtm)
Cat.
µg/l
>0.1
µg/l
0.1
II
-
>0.02
-
<0.008
0.1
>0.1
(0.02)
0.1 *
0.01-0.1
(0.01-0.1)
<0.1 *
0.01
0.002
0.005-0.01
0.002-0.1
(0.01-0.1)
III
II
I
II
I
I
II
I-III
For Table 5 and Table 6 the monitoring report describes the categories as follows:
Category III: Reliable data (i.e. analytical method with specific detection and including analytical quality control).
Category II: Moderately reliable data (e.g. adequate analytical methods but no information on analytical quality control, or
insufficient information to assign to Category III).
Category I: Reliability uncertain (e.g. screening only with semi-quantitative method, such as immunoassay based techniques) or
inadequate information to determine reliability of data, or data compiled from various sources with little information concerning the
reliability of the data.
Trifluralin concentrations in surface water were in the range 0.2-0.7 μg/l for Belgium, France, Greece and UK.
A large number of negative findings have been reported from, Switzerland, Austria, Italy and the
International Rhine Commission [OSPAR, 2005].
One case of non-compliance with the drinking water standard of 0.1 μg/l has been reported for UK in 1994.
One case was reported from Germany, where remedial measures were implemented at one site for the
abstraction of drinking water from surface water, although the trifluralin concentration (0.05 μg/l) was below
the drinking water limit at this site. These findings relate to a large amount of data from Germany, Ireland
and the UK, and a small number of samples from the Netherlands [OSPAR, 2005].
Occurrence of trifluralin in ground water is reported to be rare (Table 5). Only few samples of over 12000
from almost 3500 sites analysed contained detectable amounts of trifluralin (Austria (1 of 7000 samples,
1992-1997), France (1 of 336 samples, 1997), UK (6 of 517 samples, 1999)). The highest concentration
reported was 0.1 μg/l (one report from Austria) [OSPAR, 2005].
Trifluralin has also been found in sediments in France and Great Britain. France reported 2450 individual
measurements of trifluralin in sediment. However, all but four of these measurements were below the
determination limit (5-100 μg/kg). In three cases the limit of quantification was given to 1000 μg/kg. Four
measurements were quantified with 66, 95, 156 and 220 μg/kg [OSPAR 2005].
According to reviewed monitoring data from the EU, Switzerland and Norway, trifluralin occurrence in
ground water is rare. Trifluralin was more frequently found in surface waters with maximum concentrations
between 0.2 μg/l and 0.7 μg/l. In the countries where trifluralin is found in surface waters, positive samples
15
range between 4 % and 16.4 % of the analysed samples, but only a maximum of 3.2 % of the samples were
above 0.1 μg/l. (quoted from [EFSA 2009]).
USA
In the USA, trifluralin was found in 172 of 2047 surface water samples and one of 507 ground water samples
analysed. The 85th percentile of the levels in all non-zero surface water samples was 0.54 μg/L [WHO 2003].
It can be concluded that new monitoring data on environmental occurrence for trifluralin are scarce.
Therefore, the most relevant information, which partly is already known from the EC Trifluralin Risk Profile
and the OSPAR report on trifluralin, was summarised. New data provided from AMAP is also indicated and
new field studies carried out in the United States have been incorporated.
The information evidence the long-range transport of trifluralin and further shows its occurrence in
biota.
16
4
Transformation products of trifluralin
Several transformation products of trifluralin have been identified in soil, water and sediment tests.
According to the laboratory and field studies to the major metabolites of trifluralin belong TR-42, TR-63, TR144 and TR-155. Further, numerous minor transformations products of trifluralin were detected. In the
following more detailed information is given for possible transformation and degradation of the substance
under different environmental conditions. Nevertheless, respective laboratory and field studies should be
considered for precise description of the complex transformation processes.
SOIL
Trifluralin was steadily degraded in soil under aerobic conditions. No major metabolites are formed. Only
some minor metabolites are formed by oxidative dealkylation of N-propyl, reduction of nitro groups with
cyclation and dimerization to form azoxy-benzene compounds [EFSA 2009]. European and US field studies
showed that the substance dissipates slowly in soil. Slower dissipitation was also observed in colder climates
[EC 2007]. It can be concluded that trifluralin is persistent in soil. In soil, no major metabolites were observed
so far.
Under anaerobic conditions in soil, the degradation of trifluralin is more extensive. One major metabolite,
TR-4; is formed. Under flooded anaerobic conditions TR-4 has a maximum of 13.2% applied radioactivity (AR)
after 60 days. Also TR-7, TR-14 and TR-16 may be attributed to anaerobic conditions [EC 2007]. These were
formed by sequential reduction of the nitro groups on the parent molecule (TR-4 and TR-7) or by oxidative
dealkylation of the N-propyl group on an aerobic metabolite (TR-13) followed by reduction of the nitro group
(TR-14). Latter was formed at above 5% at the end of a study cited by EFSA 2009. TR-14 had a maximum of
8.3% AR after 60 days. Under anaerobic conditions the levels of evolved volatile components were less
significant than under aerobic conditions (quoted from [EC 2007].
On the environment expert meeting, it was not possible to exclude the relevance of anerobic conditions for
the representative uses. Further, it was concluded that, based on the molecular structure, TR-4 would be
degraded under aerobic conditions. As the levels found for TR-14 are lower than for TR-4 and that it is
expected to follow a degradation route analogue to other aerobic metabolites, the same conclusion reached
for metabolite TR-4 is applicable to TR-14 [EFSA 2009].
According to the soil photolysis study indicated by EFSA 2009, photolysis is not expected to be a significant
degration route of trifluralin. No major photolysis products were identified in the environment.
A batch adsorption/desorption study in four soils is available for trifluralin. The data indicate that trifluralin is
strongly adsorbed to soil (KFoc = 6414 – 13414 mL/g) and may be classified as immobile. For the anaerobic
metabolite TR-4 a Koc = 13600 mL/g was estimated, using the “pckocwin v.1.66 (EPA)” program, indicating
also low mobility potential for this metabolite. The PRAPeR TC 10 meeting of experts discussed the
acceptability of the Koc value estimated for metabolite TR-4. The experts agreed that the value may be
considered reasonable when used together with a 1/n = 1 to model the EU representative uses. However, if
an assessment at national level indicates that the exposure approaches a groundwater trigger or surface
water tier 1 risk assessment trigger, then measured data on adsorption could be needed to assess uses
2
TR-4: 3-nitro-N2,N2-dipropyl-5-(trifluoromethyl)benzene-1,2-diamine
TR-6: 3-nitro-5-(trifluoromethyl)benzene-1,2-diamine
4
TR-14: 2-ethyl-1-propyl-5-(trifluoromethyl)-1H-benzimidazol-7-amine
5
TR-15: 2-ethyl-7-nitro-5-(trifluoromethyl)-1H-benzimidazole
3
17
where anaerobic soil conditions cannot be excluded. Two aged residue column leaching studies with a total
of three experiments are available (quoted from [EFSA 2009]).
Amounts between 0.42 to 2.54 % AR are found in the leachate. However, this radioactivity may not be
attributed to the parent compound and was not further identified. More data on the leaching potential of
metabolite TR-4 was initially requested by the rapporteur Member State in the Draft Assessment Report
pending decision on its relevance. According to the conclusions of the fate and behaviour in the environment
EPCO expert meeting no further data for this metabolite are necessary to finalise the assessment made in
the context of Annex I inclusion. (quoted from [EFSA 2009])
Trifluralin degrades with a reported half-life of 41 days when exposed to a light source on sandy loam soil.
The half-life of dark control samples of trifluralin was reported to be 66 days. Two degradation products, 2,6dinitro-N-propyl-4-trifluoromethylbenzenamine and 2-ethyl-7-nitro-5-trifluoromethylbenzimidazole-3-oxide
were identified in the light-exposed samples (US EPA, 1996 quoted from [EC 2007]).
AIR
Because of its high volatility (vapour pressure= 9.5 x 10-3 Pa (25 °C) and Henry's law constant = 10.2 Pa m3
mol-1 at 20°C), trifluralin may occur in air and may be transported through air. However, the photochemical
oxidative degradation half-life of trifluralin in air is rapid (5.3 hours or 0.22 days) estimated with SAR method
(Atkinson). Hence, the calculated value is under the trigger of 2 days established to represent a concern for a
potential long-range transport by the Stockholm Convention ([EFSA 2009]; [EC 2007]). No further
information on volatilization and potential long-range transport of trifluralin is available [EFSA 2009].
WATER AND WATER SEDIMENT SYSTEMS
Trifluralin is hydrolytically stable in sterile aqueous buffers between pH 3 and pH 9 at 52°C with an
extrapolated half-life above one year at 20°C. Aqueous photolysis may contribute to the environmental
degradation of trifluralin (DT₅₀ irr. = 7 h vs. DT₅₀dark = 480 h). Aqueous photolysis is enhanced in natural water
(DT₅₀ = 1.1 h) [EFSA 2009].
Photodegradation of trifluralin led to the formation of the major photoproducts TR-6 (maximum of 50.4 %
AR at the end of the study after 48.5 hours continuous irradiation) and TR-15 (maximum of 31.5 % AR at the
end of the study after 48.5 hours continuous irradiation). Initial PECsw values have been calculated based on
the maximum amounts observed in the photolysis study and it could be concluded that trifluralin is not
readily biodegradable [EFSA 2009].
Trifluralin dissipated from the system mainly by volatilization. Dissipation half-life of trifluralin in the whole
system was 4.9- 5.9 days. Half-life for trifluralin in the water phase was estimated to be 13 days based on the
worst case system (sandy loam) [EFSA 2009].
Another water sediment system where trifluralin was applied to the sediment showed TR-4 as the major
metabolite (max 16 % after 28 days). The substance was identified in the sediment phase. The water phase
was not analysed in this system since radioactivity was below 10 % AR in all samples [EFSA 2009].
Another two water sediment systems were studied where the test substance was applied to the sediment.
Three major metabolites were found in the sediment: TR-4 (maximum of 27 % AR after 7 days), TR-76
(maximum of 14.2 % AR after 33 days) and TR-14 (maximum of 29.5 % after 54 days). Non-identified
6
TR-7: N2,N2-dipropyl-5-(trifluoromethyl)benzene-1,2,3-triamine
18
compounds (up to 23 % AR) were shown to be the sum of multiple peaks of minor components. Nonextractable residues (NERs) grow up to a maximum of 77 % AR and are associated with the humin fraction.
No volatiles were observed in this study. Dissipation half-lives in the water phase in these systems are one
and two days based on the only three data points (0 – 3 days) where trifluralin was observed in the aqueous
phase [EFSA 2009].
The calculated concentration (estimation with FOCUS PELMO 1.1.1.) for TR-4 in ground water for both
compounds was negligible in all scenarios. The results confirmed that 80th percentile annual average
concentration over the 20 years simulation period is expected to be below the regulatory limit of 0.1 ìg/L.
Reliable calculations with a second model are not available [EFSA 2009].
Conclusion on transformation products
Several transformation products of trifluralin have raised attention in the soil, water and sediment tests.
According to the laboratory studies and field studies, cited in EFSA 2009, UNECE 2007, OSPAR 2005 and
EUTTF 2002, the following conclusions can be made:
Under aerobic conditions, degradation from trifluralin in soil did not lead to any major transformation
products. However, a number of minor metabolites could be identified.
Under anaerobic conditions, the formation of the major metabolite TR-4 and in a lesser extent TR-14 was
found. It was concluded that based on its molecular structure, TR-4 would be degraded under aerobic
conditions. However, the ecotoxicology should be examined in further studies for specific environmental
conditions.
TR-14 levels are lower than for TR-4. Under aerobic conditions it is expected that the degradation route of
TR-14 is analogous to the one of TR-4. Therefore, the same conclusion for metabolite is as well applicable to
metabolite TR-14.
TR-4 was a major metabolite in one of the water sediment systems (up to 27% AR). In a new water sediment
study where the test substance was applied to the sediment, three metabolites of trifluralin were identified
in the sediment: TR-4, TR-7 and TR-14. NERs grow up to a maximum of 77 % AR. However, considering the
identified and non-identified compounds it seems clear that significant degradation occurs. It is debatable to
which degree the NERs should be considered as degradation and/or to which degree the NERs may be or
may become bioavailable trifluralin.
At the end of the studies in soil and in water sediment systems low levels of TR-4 were observed at the end
of the studies which might indicate a further degradation of TR-4.
According to the soil photolysis study, it is not expected that the degradation route of trifluralin in the
environment and that no major photolysis products were found.
With regard to surface water analyses the following can be concluded: In the water compartment of water
sediment studies no major metabolites were found. The two major photoproducts TR-6 and TR-15 were
identified in the photolysis study.
The provided results from the modeling of the anaerobic metabolite TR-4 with FOCUS PEARL showed that
the annual average leachate concentration is expected to be below the regulatory limit. Thus, the
19
contamination of the ground water with trifluralin and its degradation products is considered to be not
probable.
No metabolites could be identified in air studies. The photochemical half-life in air, calculated with SAR
method, was 5.3 hours. This value is under the trigger established to represent a concern for potential LRT
set by the Stockholm Convention.
The PBT criteria of the examined trifluralin metabolites have been partly explored:
The effects of TR-4 were tested on larvae of midge Chrionomus riparius sediment water exposure system
(NOEC 0.332mg a.s./L nominal), earthworms (NOEC (14d) 100 mg a.s./kg dry soil nominal) and soil microflora
activity (<25% deviation from values after 29 days up to 2 mg a.s./kg dry soil). In relation to the
corresponding PEC-values for sediment and soil, toxicity exposure ratios (TERs) exceeded the trigger values
by far, indicating that there is no unacceptable risk by this metabolite (quoted from [OSPAR 2005]).
Ecotoxicity tests for TR-6 and TR-15, major metabolites from photolysis in aqueous sterile buffer, were
performed. The results in algae, daphnids and fish (EC₅₀/LC₅₀ values of 1-5mg/l) showed that these
transformation products are less toxic than the parent compound trifluralin.
Table 7:
Overview of parent and all relevant metabolites requiring further assessment from the fate section [EFSA
2009]
Compartment
Soil
Water
Sediment
Groundwater
Trifluralin
Trifluralin, TR-6, TR-15
Trifluralin, TR-4, TR-7, TR-14
Trifluralin
It can be concluded that several major transformation products of trifluralin have been identified, especially
in soil. However, as the information on their persistence, toxicity and bioaccumulation is very limited, further
information would be needed for an assessment of their POP characteristics.
20
5
References
[AMAP 2005]
Skov, H.; Bossi, R., Wåhlin, P., Vikelsøe, J., Christensen, J.; Egeløv, A.H.; Zeuthen Heidam, N; Jensen, B.,
Ahleson Lizzi Stausgård, H.P. , Jensen, I., Petersen, D. 2005. Contaminants in the Atmosphere AMAPNuuk. Westgreenland 2002-2004. NERI Technical Report, No. 547.
[Barr et al. 2010]
Dana Boyd Barr, Cande V. Ananth, Xiaoyong Yan, Susan Lashley, John C. Smulian, Thomas A. Ledoux,
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Chernyak SM, Rice CP, McConnell LL. Evidence of currently-used pesticides in air, ice, fog, seawater and
surface microlayer in the Bering and Chukchi Seas. Mar Pollut Bull 1996;32:410–9.[EC 2007]
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Pollution on Persistent Organic Pollutants (LRTAP Protocol on POPs). European Commission, DG
Environment, Brussels, July 2007.
[EFSA 2009]
European Food Safety Authority, EFSA Scientific Report (2009) 327, 1-111: Peer review of the pesticide
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