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EC number: 942-466-6 | CAS number: -
The calculation of the DNELs is performed in accordance with the principles given in ECHA (2012) “Guidance of Information Requirements and Chemical Safety Assessment, Chapter R.8: Characterisation of dose [concentration]-response for human health”.
Available dose descriptors:
The target substance (Reaction product of diphosphorus pentaoxide and alcohol C7 -9 -iso, C8 rich, salted with 2 -ethylhexylamine) is not acutely toxic by oral and dermal routes of exposure because LD50 values are > 2000 mg/kg bw for the read-across substance (Phosphoric acid, mono and di-(C8 -C10) ester, salted with C12 -C14 amine) (Sanders, 1998a,b). Inhalation is not relevant route of exposure due to the low vapour pressure of the substance (0.0004 Pa at 25 °C ) (Tremain, 2013b). The target substance is non-volatile and therefore no risk of irritation or sensitisation of respiratory tract exists.The read-across substance is not irritating or sensitising to skin (Sanders, 1998c; Coleman, 1999). Therefore, no DNELs for acute/short-term exposures (systemic and local effects) and for long-term exposures (local effects for both inhalation and dermal routes) need to be derived.
For the long-term exposure – systemic effects (inhalation and dermal DNEL), the NOAEL of 500 mg/kg bw established in the Oral-Reproduction/Developmental Toxicity Screening Study in Rats (Thorsrud, 2013) was used as the starting point. This is the lowest NOAEL known for the target substance after repeated exposures to rats. The DNELs for inhalation and dermal routes can be derived by route-to-route extrapolation applying appropriate assessment factors.
For the other non-threshold endpoints (mutagenicity, eye and skin irritation/corrosion) no DNELs can be derived because a No-Observed-Effect-Level could not be established from the relevant studies.
Modification of the starting point:
From all available data on the target and read-across substances it is clear that these substances exert their effects by a threshold mode of action. Thus, DNELs can be calculated for the threshold endpoints based on the most relevant dose descriptors per endpoint. DNELs are derived based on the available toxicity data for the target substance and reflecting the routes, the duration and the frequency of exposure. DNELs are derived for workers and the general population. The general population includes consumers and humans exposed via the environment (please see below).
There is no substance-specific experimental information on absorption by the oral, dermal and inhalation routes available. The absorption rates are assessed based on the physico-chemical properties and on the effects observed in treated animals in the available studies.
Based on the average molecular weight of 400and 490 g/mol for the representative structures of the target and read-across substance, respectively, and the logPow values favourable for absorption via gastrointestinal tract, absorption by oral route is significant. Moreover, the salted alkylamine phosphates will dissociate under acidic condition of the stomach releasing alkyl phosphates and alkyl amine. Alkyl phosphates (di and mono) could further be hydrolysed to phosphoric acid and corresponding fatty alcohols which together with alkylamines have probably a deviating pattern of absorption from those of the parent (salted) compound. The absorption of released alkyl phosphate and alkylamine constituents is expected to be easier than that of the original compound. Taken this fact into account together withthe effects found at the mid and the highest dose level in the Oral-Reproduction/Developmental Toxicity Screening Study in Rats (Thorsrud, 2013) and the subacute study in rats (Jones et al., 1999) absorption by oral route is considered to be significant (for the detailed information on absorption please refer to section "Toxicokinetics, metabolism and distribution" of this CSR or section 7.1 of IULID file).The oral absorption is set to 100 % (worst-case) for the purposes of hazard assessment (DNEL derivation). The oral absorption is considered to be the same in animals and in humans (worst-case).
No significant dermal absorption is expected for the target substance. The log Pow values are below or above the optimal logPow values favourable for dermal absorption (0.84, 0.28, and 4.28, respectively for the amine, monoalkyl phosphate, and dialkyl phosphate analytes). On the other hand, the substance is soluble in water above 1 mg/L where dermal uptake is anticipated to be low to moderate. The average molecular weight of 400 g/mol (< 500 g/mol)points to a moderateabsorption through the skin as well. Moreover, the target substance could dissociate in contact with skin and therefore breakdown products with a deviating absorption pattern are expected. Based on these data, 50 % dermal absorption is considered appropriate.Dermal absorption in rats, rabbits and in humans is assumed to be the same since no information for dermal absorption of the target substance in humans is available.
Absorption by inhalation is considered to be negligible (low vapour pressure of 0.0004 Pa at 25 °C) and not to be higher than absorption by oral route. However, 100 % absorption is assumed for inhalation route (in case of the route-to-route extrapolation) and considered to be equal in rats and in humans since no substance specific information is available.
Oral-to-inhalation extrapolation is performed to obtain long-term inhalation NOAEC for systemic effects. The following formula was used:
Corrected inhalatory NOAEC = oral NOAEL x (1/sRVrat) x (ABSoral-rat/ABSinh-human) x (6.7 m³/10 m³) where sRV is the standard respiratory volume of rats during 8 hours (= 0.38 m³/kg/day); ABS-absorption and 6.7 m³ and 10 m³ are standard respiratory volumes for workers under normal conditions and by light activity.
Oral-to-dermal extrapolation is performed to obtain dermal NOAEL for systemic effects. The following formula was used (as described in the Example B.5 of the Appendix R.8 -2, ECHA REACH Guidance R8):
Corrected dermal NOAEL = oral NOAEL x (ABSoral-rat/ABSderm-rat) x (ABSderm-rat/ABSderm-human) = oral NOAEL x (ABSoral-rat/ABSderm-human).
No modification of the starting points for exposure conditions was necessary since the systemic dose after oral administration of the test material was already assessed in respiratory volume taken for rats during 8 h (0.38 m³).
Differences in the respiratory volumes between experimental animals and humans were used when an oral rat NOAEL from the oral one-generation reproductive toxicity study in rats was used to assess inhalation exposure in humans. 0.38 m³/kg/day is the standard respiratory volumes in rats during 8h exposure. 6.7 and 10 m³ are standard respiratory volumes for workers under normal conditions and by light activity, respectively.
Applying of assessment factors and calculation of DNELs:
The assessment factors have been applied to the corrected starting point to obtain the endpoint specific DNELs. Assessment factors (AFs) correct uncertainties and variability within and between species in the effect data.
The species-specific default assessment factor of 4 for allometric scaling for rats was applied in the case of employment of the oral NOAEL from the Oral-Reproduction/Developmental Toxicity Screening Study in Rats, which was used to derive the dermal long-term DNEL.
No allometric scaling factor was applied when the oral NOAEL was used for the derivation of inhalation long-term DNEL.
An assessment factor of 2.5 was applied for remaining interspecies differences in toxicodynamics between rat and human in all cases.
An assessment factor of 5 was applied for workers for all endpoints and for all exposure routes.
Extrapolation of duration:
An assessment factor of 6 was applied for duration of exposure (Screening study = sub-acute).
Quality of whole data base:
A default assessment factor of 1 was used.
Issues related to dose response:
A default assessment factor of 1 was applied when the NOAEL from theOral-Reproduction/Developmental Toxicity Screening Study in Rats was used (there was a clear dose response).
Calculation of DNELs:
Long-term exposure – systemic effects (inhalation DNEL):
The oral rat NOAEL of 500 mg/kg bw was converted into the inhalation NOAEC:
Inhalation NOAEC = oral NOAEL x (1/sRVrat) x (ABSoral-rat/ABSinhal-human) x (6.7 m³/10 m³) = 500 mg/kg bw x (1/0.38 m³/kg/day) x (100 %/100 %) x (6.7/10) = 881.6 mg/m³
DNEL = 881.6 mg/m³/(2.5 x 5 x 6 x 1 x 1) = 11.8 mg/m³.
Assessment factors are: 2.5 – remaining interspecies differences, 5 – intraspecies, 6 – study duration (sub-acute study), 1 – dose response, 1 – quality of data base. The total AF amounts to 75.
Long-term exposure – systemic effects (dermal DNEL):
For the oral rat NOAEL of 500 mg/kg bw the following conversion was necessary:
Dermal NOAEL =oral NOAEL x (ABSoral-rat/ABSderm-human) = 500 x (100 %/50 %) = 1000 mg/kg bw
DNEL = 1000 mg/kg bw/(4 x 2.5 x 5 x 6 x 1 x 1) = 3.3 mg/kg bw.
Assessment factors are: 4 – interspecies, 2.5 – remaining interspecies differences, 5 – intraspecies, 6 – study duration (sub-acute study), 1 – dose response, 1 – quality of data base. The total AF amounts to 300.
DNEL systemic inhalation = 11.8 mg/m³
DNEL systemic dermal (long-term) = 3.3 mg/kg bw
The principles of the DNEL calculation for the general population are the same as already described for workers. However, there are additional considerations or deviations for:
The oral absorption in rats and in humans is assumed to be the same since no information for oral absorption for the target substance in rats and in humans is available.
No differences in the respiratory volumes under normal conditions and by light activity in humans were taken into account. A default respiratory volume of 1.15 m³/kg bw/day for rats was used to convert oral NOAEL into inhalation NOAEC.
Applying of assessment factors:
A higher assessment factor of 10 (in place of 5 for workers) for intraspecies variation/differences of human population was used.
Calculation of endpoint-specific DNEL for general population
Long-term exposure - systemic effects (inhalation):
The oral NOAEL of 500 mg/kg bw was converted into the inhalation NOAEC:
Corrected inhalation NOAEC = oral rat NOAEL x (1/1.15 m³/kg bw/day) x (ABSoral-rat/ABSinhal-human), where 1.15 is the standard respiratory volume (m³/kg bw) of rats during 24 h exposure, ABS is absorption (values are the same as described for workers).
Corrected Inhalation NOAEC = 500 mg/kg bw x (1/1.15 m³/kg/day) x (100 %/100 %) = 434.8 mg/m³
DNEL = 434.8 mg/m³/(2.5 x 10 x 6 x 1 x 1) = 2.9 mg/m³.
Assessment factors are: 2.5 – remaining interspecies differences, 10 – intraspecies, 6 – study duration (sub-acute study), 1 – dose response (clear dose response), 1 – quality of data base (default). The total AF amounts to 150.
Long-term exposure - systemic effects (dermal):
Dermal NOAEL = oral NOAEL x (ABS oral-rat/ABS dermal-rat) x (ABS dermal-rat/ABS dermal-human) = 500 x (100 %/50 %) = 1000 mg/kg bw
DNEL = 1000 mg/kg bw/(4 x 2.5 x 10 x 6 x 1 x 1) = 1.7 mg/kg bw.
Assessment factors are: 4 – interspecies, 2.5 – remaining interspecies differences, 10 – intraspecies, 6 – study duration (sub-acute study), 1 – dose response, 1 – quality of data base. The total AF amounts to 600.
Long-term exposure - systemic effects (oral):
The oral NOAEL of 500 mg/kg bw had not to be converted.
The oral NOAEL of 500 mg/kg bw was not modified for differences in absorption by oral route in rats and in humans since no substance- and route specific information is available: oral absorptionrat= oral absorptionhuman.
DNEL = 500 mg/kg bw/(4 x 2.5 x 10 x 6 x 1 x 1) = 0.83 mg/kg bw. Assessment factors are: 4 – interspecies, 2.5 – remaining interspecies differences, 10 – intraspecies, 6 – study duration (sub-acute study), 1 – dose response (clear dose response), 1 – quality of data base (default). The total AF amounts to 600.
DNEL systemic inhalation = 2.9 mg/m³
DNEL systemic dermal (long term) = 1.7 mg/kg bw
DNEL systemic oral (long-term) = 0.83 mg/kg bw
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