Zinc dilaurate

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Persistence:

The biodegradation of octanoic acid, zinc salt, basic (CAS 90480-58-3) after 28 days was 80% and 86% at 30 mg/L and 100 mg/L, respectively, meeting the 10-day window criteria. Thus, octanoic acid, zinc salt, basic, i.e. a zinc salt of a shorter-chained (C8) fatty acid, is readily biodegradable. Zinc stearate is readily biodegradable as the 60% level was passed within 28 days but failed the 10 day window criteria. Zinc bis[12-hydroxyoctadecanoate] is also readily biodegradable as the 60% level was passed within 28 days but failed the 10-day window criteria. Thus, similar biodegradation rates are observed in different tests with zinc salts of shorter-chained (C8) and longer-chained (C16-18) fatty acids. It is concluded that zinc dilaurate is also readily biodegradable.

The concept of “biodegradability” has been developed for organic substances and is not applicable to inorganic substances, including zinc. As a surrogate approach for assessing “degradability”, the concept of “removal from the water column” has been developed to assess whether or not a respective metal ion would remain present in the water column upon addition (and thus be able to exert a chronic effect) or would be rapidly removed from the water column. In this concept, “rapid removal” (defined as > 70% removal within 28 days) can be considered equivalent to “rapid degradation”. For zinc in water, information is available on the removal of zinc from the water column. The removal from the water column was modelled referring to the EUSES model parameters and different conditions of pH. Zinc is removed by > 70% under the reference conditions for the EU regional waters (EUSES). Consequently, zinc is considered as equivalent to being ‘rapidly degradable in the context of classification for chronic aquatic effects.

In accordance to the criteria laid down in Regulation (EU) No 253/2011, substance zinc dilaurate can be regarded as “not P” and “not vP”.

Bioaccumulation:

Based on read-across of zinc bioaccumulation data and the fact that zinc dilaurate is readily biodegradable, bioaccumulation and biomagnification are not expected to be relevant for zinc dilaurate. These conclusions are similar to the conclusions for the structural analogue from the EU RAR Zinc distearate (CAS-No.: 557-05-1 & 91051-01-3 EINECS-No.: 209-151-9 & 293-049-4) Part 1 - Environment (Final report R074_0805_env, May 2008):

"Based on data on bioaccumulation of zinc in animals and on biomagnification (i.e. accumulation and transfer through the food chain), secondary poisoning is considered to be not relevant in the effect assessment of zinc..." "Distearate is not expected to bioaccumulate, knowing that fatty acids will degrade by the β oxidation pathway."

In accordance to ECHA TGD R.11.1.3.2, substance zinc dilaurate can be regarded as “not B” and “not vB”.

Toxicity:

Zinc dilaurate does not fulfil the toxicity criterion (T-):

The long-term no-observed effect concentration (NOEC) for marine or freshwater organisms is not less than 0,01 mg/L. Substance zinc dilaurate does not meet the criteria for classification as carcinogenic (category 1A or 1B), germ cell mutagenic (category 1A or 1B), toxic for reproduction (category 1A, 1B, or 2) and specific target organ toxicity after repeated exposure according to Regulation (EC) No 1272/2008. Thus "T" criteria in respect of long-term toxicity to marine / freshwater organisms, carcinogenicity, germ cell mutagenicity, toxicity to reproduction or chronic toxicity as laid down in Regulation (EU) No 253/2011 are not fulfilled.

PBT/vPvB outcome:

Substance zinc dilaurate is not classified as PBT or vPvB.