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Administrative data

Link to relevant study record(s)

Description of key information

Absorption

Dermal: 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.

Absorption via the oral route of exposure is not likely to occur given the normal use patterns of Technical Grade.

Technical Grade only exists in liquid form and, based on the substance's low vapour pressure (0.0002 Pa at 25oC), exposures via inhalation that lead to absorption through the respiratory system are unlikely.

Distribution:Given the low water solubility of Technical Grade (and the different forms of cardanol and the polymeric constituents), any absorbed chemical will probably be distributed through the body via the lipids rather than by circulation in the blood. In the OECD TG408 Repeated Dose 90-day Toxicity studies on Distilled and Distillation Residue Grades the responses, though largely non-adverse, indicated that the different forms of cardanol had been distributed to the liver, mesenteric lymph nodes and thyroid gland.

Metabolism:Given the test substances high measured partition coefficient (log Kow of > 6.2), it is expected that the bioavailability of the different constituents for metabolism will be reduced. The liver is expected to be the primary organ to receive and metabolize the different forms of cardanol, making them more soluble by oxidation and conjugation and releasing the more polar compound into the bile for elimination via the gastrointestinal tract. Any chemical which is not metabolized is expected to be excreted either through the urine or faeces. However, it is recognised that it is difficult to predict the metabolic changes that the different constituents of Technical Grade may undergo on the basis of physico-chemical information alone (ECHA, 2017).

Excretion:There is no reported data available on the excretion of any absorbed constituents of Technical Grade. The major routes of excretion for substances from the systemic circulation are the urine and/or the faeces (via the bile and directly from the gastrointestinal mucosa). For constituents such as cardanol, which show low water solubility and a molecular weight of 298 to 304 g/mole, it is more likely that they will be excreted in the bile rather than in urine (ECHA, 2017)

Accumulation potential:Although the high log Kow values for the different forms of cardanol indicate they would be expected to accumulate in the body of organisms, low Bioconcentration Factors (BCFs) values were measured in an OECD TG305 Bioconcentration in Fish study for another grade of CNSL (Distilled Grade). The individual BCF values obtained for the four forms of cardanol, both before and after lipid normalisation, were <2000 L/kg. A BCF of 2000 L/kg is the threshold for a test substance to be considered to be bioaccumulative meaning the different forms of cardanol should not accumulate within the body. It is anticipated that a similar result will be obtained in the test on Technical Grade given the presence of a significant proportion of larger size, higher molecular weight polymeric constituents that are not expected to bioaccumulate.

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential
Absorption rate - dermal (%):
100

Additional information