Registration Dossier

Administrative data

Endpoint:
dermal absorption
Type of information:
other: Expert review and assessment derived from available information
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data

Data source

Reference
Reference Type:
other company data
Title:
Unnamed
Year:
2020
Report Date:
2020

Materials and methods

Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
Expert review of available data
GLP compliance:
no

Test material

Reference
Name:
Unnamed

Results and discussion

Absorption in different matrices:
The rate and extent of absorption cannot be elucidated from the data available.

Any other information on results incl. tables

There are no toxicokinetic studies that have directly addressed the absorption, distribution, metabolism, or excretion of Technical Grade. However, information on these processes have been inferred based upon the properties of the chemical and the results of reliable and relevant longer-term mammalian toxicity tests based on guidance given in ECHA (2017).

The only likely route of absorption of the different constituents of Technical Grade is via dermal exposure due to the industrial use patterns of the test substance identified in the Risk Characterisation Exercise. However, the lipophilicity of the different forms of cardanol (estimated log Kow values >8.31for all forms) and their molecular weights (298 to 304 g/mole) means that the expected rate of transfer of substances between the stratum corneum (the non-viable layer of corneocytes forming a complex lipid membrane that must be first penetrated) and the epidermis (which is resistant to penetration by highly lipophilic substances) will be slow and will limit absorption across the skin. In addition uptake of the Technical Grade constituents into the stratum corneum itself may also be slow unless any damage to the skin surface caused by Technical Grade (an identified irritant) enhances penetration (ECHA, 2017). Technical Grade also contains a high proportion of larger size and higher molecular weight polymeric constituents which are expected to have more limited absorption through the skin than the different forms of cardanol.

Evidence for limited skin absorption is provided by an Acute Dermal Toxicity study (OECD TG402) on another grade of CNSL, Distilled Grade, where Wistar rats that were exposed to a single dose of 2000 mg/ kg body weight for 24 hours showed no signs of systemic toxicity throughout the 14-day observation period. Signs of systemic toxicity would be an indication that absorption has occurred. At the end of the test all animals were subjected to an external examination and opening of the abdominal and thoracic cavities. No abnormalities were noted at necropsy.

Applicant's summary and conclusion