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EC number: 219-417-6
CAS number: 2432-99-7
Conversion into an inhalatory rat NOAEC by dividing by 0.38 m3/kg (8-hour respiratory volume in the rat)
*No correction for inhalatory and oral absorption rates (considered to be 100 % because 11-aminoundecanoic acid is well absorbed by both routes)
*Correction for activity driven differences in respiratory volume in workers compared to individuals at rest (6.7 m3/10 m3)
*Corrected dose descriptor:NOAEC (worker, 8 h)= 79 x 1/0.38 x 6.7/10 = 139 mg/m3
DNEL Value based on NOAEL OECD 421 :
79 x 1 x 1/(2.5 x 4 x 5 x 6 x 1 x 1) = 0.26 mg/kg bw
For acute effects, no significant effects that would justify DNEL derivation were observed in the corresponding toxicity studies.
For systemic effects, DNEL derivation was performed following the method proposed in the ECHA Guidance on information requirements and chemical safety assessment, Chapter R.8.
1. Long term exposure-systemic toxicity
1.1 Inhalation DNEL(workers)
Occupational exposure to 11 -aminoundecanoic acid may occur mainly by inhalation of particles, therefore we consider the inhalation route as the most relevant for DNEL derivation.
Of all repeated dose toxicity studies in rats, the OECD TG 421 (reproductive/developmental screening) study (CIT, 2008) is selected for DNEL derivation as it is the study where the lowest NOAEL was observed among the repeated dose toxicity studies data set with 11-aminoundecanoic acid, and because effects on kidneys, considered as the critical effect with a threshold mode of action, were also observed in this study.
*NOAEL (parental toxicity) = 1250 ppm, equivalent to79 mg/kg/day
*No reproductive effects but renal effects were observed in the parents (histopathological findings).
*Conversion into an inhalatory rat NOAEC by dividing by 0.38 m3/kg (8-hour respiratory volume in the rat)
*Interspecies : no allometric scaling factor is applied because an oral-to-inhalation route extrapolation is performed. However, a factor of 2.5 to correct for differences other than differences in metabolic rate is applied.
*Intraspecies : the default assessment factor of 5 is applied.
* Differences in exposure duration: as the exposure in rats was 54 days, a factor of 6 for subacute-to-chronic extrapolation is applied.
*Dose-response relationship: a factor of 1 is applied due to the use of a NOAEL as dose descriptor and the low toxicity of the test substance.
*Quality of whole database: a factor of 1 is applied based on the good quality of the whole database.
*Global assessment factor: 2.5 x 5 x 6 x 1 x 1 = 75
Worker DNEL (long term, systemic effects)= 79 x 1/0.38 x 6.7/10 x 1/75 = 1.86 mg/m3
2. Dermal DNEL (workers)
Occupational exposure to 11 -aminoundecanoic acid may also occur by dermal exposure. Although no dermal repeated dose toxicity studies is available as well as no information on dermal absorption, we derived a dermal DNEL based on the Oral NOAEL selected for the derivation of the inhalation DNEL.
Step 1) Relevant dose-descriptor
* NOAEL, rats= (parental toxicity) =1250 ppm, equivalent to79 mg/kg/day
Step 2)Modification of starting point:
* Correction for oral to dermal absorption :
11 -aminoundecanoic acid has a low octanol partition coefficient (log Kow=0.16) which predicts a low dermal absorption. However as no dermal penetration study is available we consider 100% absorbsion as a worst case (=1).
No difference in dermal absorption is expected between rats and humans, no correction factor will be applied.
Step 3) Assessment factors
* Interspecies: 2.5 x 4
* Intraspecies : 5
* Exposure duration : 6 (as the exposure in rats was 54 days, a factor of 6 for subacute-to-chronic extrapolation is applied).
* Dose response:1
* Quality of database:1
The oral route of exposure is not relevant to workers.
see discussion below
79 mg/kg/day x1/1.15=67.94 mg/m3
exposure to 11 -aminoundecanoic acid is the most relevant potential
safety concern under the conditions of use of the substance. There is no
direct consumer use of 11 -aminoundecanoic acid, Food contact materials
made of polyamide 11 contain low residual levels of 11-aminoundecanoic
acid (<100 ppm) and are subject to very strict regulations, therefore no
DNEL derivation for general population was deemed necessary.
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