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EC number: 202-486-1
CAS number: 96-18-4
values of algae, daphnia, and chronic fish studies are available. For
the invertebrates though, the chronic NOEC is higher for daphnia than
the EC50 reported for Cerodaphnia. In the absence of better
documentation of the testing performed, the study is considered as a
valid basis for deriving the PNEC and the chronic Daphnia is therefore
not considered for the choice of the assessment factor. Thus the PNEC
can be derived on the basis of two long-term results from species
representing two trophic levels. An assessment factor (AF) of 50 applies
in this case. The lowest concentration of 4.4 mg/L is obtained from
fish. Thus the PNEC = 4.4 mg/L ÷ 50 = 0.088 mg/L = 88 µg/L. The
AF used above is in accordance with ECHA 2008a, Chapter R.10, Table
R.10-4, p 19.
Note that the CICAD document of the WHO states: “A PNEC
for surface water was estimated from the lowest EC50 value from tests
carried out in closed systems to minimize TCP losses. The 48-h EC50
value for Daphnia magna immobilization (20 mg/L) was used to
derive the PNEC, together with an uncertainty factor of 1000: PNEC = 20
mg/L ÷ 1000 = 0.02 mg/L." The data from Ceriodaphnia
cf. dubia was neglected in the assessment by the WHO.
No data specific to marine organisms is available. The PNEC marine is
derived by applying an additional assessment factor of 10 to the PNEC
freshwater. PNEC marine = 88 µg/L/10 = 8.8 µg/L.
The Equilibrium Partitioning Method was employed for the derivation of
the soil and sediment PNEC. This is based on the assignment of TCP to
Soil Hazard category 1 because of its low adsorption potential (Walton
et al 1992) in conjunction with the reported biodegradation in aerobic
soil (Anderson et al 1991) with a half life of 2.7 days and in anaerobic
sediment (Peijnenburg et al 1998) with a half life of 7 days and finally
the low toxicity to aquatic organisms with EC/LC50
> 1 mg/L for algae, daphnia and fish (ECHA 2008 Guidance on information
requirements and chemical safety assessment, Table R.7.11-2, page 131).
The Koc used was 77 as it is the lowest
value in the range from 77 to 94.7. This was considered in application
of the precautionary principle because that way lower PNECs result.
Then the PNECsoil is estimated using
equation R.10-5 (ECHA 2008), but the value for RHOsoil, being 1700
kg/m³, taken from ECB 2003, p 44 since the value given in ECHA (2008) is
obviously by error the one for RHOsusp being 1150 kg/m³.
In accordance with ECHA 2008, Guidance on information requirements
and chemical safety assessment Chapter R.10: Characterisation of dose
[concentration]-response for environment, Chapter R.10.8.2 the PNECoral
can be derived on the basis of mammalian threshold level as no data on
effects of TCP to birds are reported. Unfortunately the most relevant
120 day study design failed to reveal a NOAEL because weak effects in
males were still present at the lowest concentration. In order to
approximate the NOAEL, the obtained LOAEL is divided by 3, so that the
threshold level is assigned to 2.7 mg/kg bw per day = NOAELmammal,
oral_chr per day obtained from 120 days repeated toxicity data on rats
(IUCLID 5 section 7.5.1, Ulland & Rutter 1983).
The critical body burden (CBB) concept (McCarty 1986) assumes that
chemicals will have a specific effect once a specific internal tissue
concentration is reached, regardless of external influences and mode of
exposure and the organism or species used. The concept is also referred
to as “critical tissue residue” or “internal dose” (e.g. Escher &
Hermens 2004). It is considered reasonably well-established for
chemicals that act via a narcotic mode of action (Bailey & Thomas 2007).
Thompson & Stewart (2003) estimate Chronic CBB of 0.2 to 0.8 mmol/kg,
with an approximate indicative range of 0.1-1.0 mmol/kg. Terminology is
not always consistent, but “CBB” corresponds to a no effect level from a
longer term study (Bailey & Thomas 2007). Thus CBB significantly lower
than 0.2 mmol/kg indicate other modes of action than the polar and
non-polar narcotic ones.
The CBB is given by the lowest aquatic no observed effect
concentration and the experimental bioconcentration facor (MITI 1992).
The recent figures on TCP are characterized by the astonishing condition
that an EC50 of 4.1 mg/L reported from
a significantly sensitive aquatic invertebrate species (Rose et al 1998)
is lower than the lowest measured NOEC being 4.4 mg/L in fish (Bernheim
at al 2005). However the daphnids (Daphnia magna) acute NOEC
value is 8.4 mg/L.
The CBB of TCP is for instance based on the lowest value
The Molecular weight of TCP is =147.432g/mol =147'432 mg/mol
and thus the molar CBB is derived by:
It is to conclude that the CBB of TCP gives some evidence for the
absence of a specific mode of action, ranging in the typical array for
polar and non-polar narcotic modes of action.
In accordance with the Guidance to Regulation (EC) No 1272/2008 on
Classification, Labelling and Packaging of substances and mixtures (14
May 2009) - IHCP, DG Joint Research Centre, European Commission, chapter
4.1.3 the Classification criteria, p. 426 (chapter 220.127.116.11) given in
Table 4.1.0, for Chronic category 2 were met. The trigger
TCP fulfils the criteria for chronic category 2 as it is acute toxic to
crustaceans and is not rapidly biodegradable. The "escape clause" NOECs
> 1 mg/l for declassification is not applicable as not for all taxa with
acute toxicity in the classifiable range (≤ 100 mg/l) exist (IHCP 2009,
chapter 18.104.22.168.3, p 434).
Thus according to Regulation (EC) no 1272/2008 of the European
parliament and of the council of 16 December 2008 on classification,
labelling and packaging of substances, p. L 353/139, the
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