Octadecane

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Persistence (P) assessment

A substance is not considered to be persistent if it can be demonstrated that it has potential to degrade (via photolysis, hydrolysis and/or biodegradation).

Several biodegradation studies with related substances measured more than 70% degradation after 28 days following OECD Guideline 306 (Aunaas, 1996a&b; Brackstad, 1997; 1999; Andersen, 2006; 2008; Van Ginkel 2009a&b) and following OECD 301F, respectively (Best, 2014).

Based on the available measured data, “Hydrocarbons, C14-C20, aliphatics (≤2% aromatics)” is biodegradable.

According to ECHAs Guidance on information requirements and chemical safety assessment - Part C: PBT Assessment (2014), a substance is considered to be potentially persistent (P) or very persistent (vP) if the BIOWIN prediction has the following results (screening criteria):

- BIOWIN 2: does not biodegrade fast and BIOWIN 3 equal or more than months

- BIOWIN 6: does not biodegrade fast and BIOWIN 3 equal or more than months.

The first criterion of BIOWIN (2 and 3) results combination is not fulfilled, since BIOWIN 2 predicted a fast biodegradation and BIOWIN 3 shows weeks as result for the Ultimate Biodegradation Timeframe. Combination 2 results are also not fulfilled, since BIOWIN 6 predicted a readily biodegradability and BIOWIN 3 shows weeks as result for the Ultimate Biodegradation Timeframe.

Photodegradation in air was predicted with the help of the QSAR program AOPWINv1.92 (software by EPIWIN). The resulting half-life (DT50) of about 5.726 hours (sunlight conditions) indicates that the substance is not persistent in the atmospheric compartment (DT50 less than 2 days).

The potential of the substance to hydrolyse under environmental conditions can be excluded due to the lack of functional groups that are hydrolytically reactive under environmental conditions. Therefore, this fate process will not contribute to a measurable degradative loss of the substance from the environment.

Based on initial persistence screening, members of the Category “Hydrocarbons, C14-C20, aliphatics (≤2% aromatics)” are not expected to meet the Persistent (P) or very Persistent (vP) criteria.

 

Bioaccumulation (B) assessment

An evaluation of representative hydrocarbon structures indicates only few structures (C14 n-paraffins, C14-C16isoparaffins and several cycloparaffins in the whole carbon range of the category) meet the Bioaccumulative (B) criteria (see CONCAWE, 2010b).

It can be demonstrated by estimation with BCFBAF v3.01 that Octadecane is not to be considered as a bioaccumulable substance: the calculated BCF is largely lower than the threshold value for B (2000).

Using another QSAR model, predicts a worst case scenario for high log Kow constituents as it assumes a plateau at log BCF 3.3 (BCF 2000) for constituents with log Kow >4.3 (equivalent to carbon chain length ~9). According to this logistic function QSAR model, constituents of the Category "Hydrocarbons, C14 -C20, aliphatics (<2% aromatics)” may reach the criteria for B, however, none of the constituents meets the criteria for vB.

Supporting data from a BCF and a solid phase micro extraction (SPME) study confirm the indication of a low potential to bioaccumulate.

Based on the PBT and vPvB criteria according to Annex XIII to REACH [stipulated in the ECHA’s Guidance on information requirements and chemical safety assessment - Part C: PBT Assessment (2014)], some constituents of the Category “Hydrocarbons, C14-C20, n-alkanes, isoalkanes, cyclics, <2% aromatics” cannot be considered unlikely to be bioaccumulative.

 

Toxicity (T) assessment       

a)    Environmental toxicity

No representative structures were identified as PB or vPvB, therefore a toxicity assessment is not needed. None of the measured or calculated data for the “Hydrocarbons, C14-C20, aliphatics (≤2% aromatics)” exceed the criteria for toxicity stipulated in the ECHA’s Guidance on information requirements and chemical safety assessment - Part C: PBT Assessment (2014). Therefore the members of this category are not considered toxic (T).

b)    Human health hazard assessment      

-  Carcinogenicity

The available data indicate that members of the Category “Hydrocarbons, C14-C20, aliphatics (≤2% aromatics)” do not warrant classification for carcinogenicity under Dir 67/548/EEC or GHS/CLP.

-   Mutagenicity

Members of the Category “Hydrocarbons, C14-C20, aliphatics (≤2% aromatics)” are not genotoxic or mutagenic and do not warrant classification for carcinogenicity under Directive 67/548/EEC or Regulation (EC) No 1272/2008.

-   Reproductive Toxicity

The available data indicate that members of this category are not toxic to reproduction and do not warrant classification under Directive 67/548/EEC or Regulation (EC) No 1272/2008.

 

Conclusion

Members of the category “Hydrocarbons, C14-C20, aliphatics (≤2% aromatics)” are considered not to be T on the basis of the data relevant to human health.

 

Summary and overall conclusions on PBT and vPvB properties         

No representative hydrocarbon structures were found to meet the PBT / vPvB criteria.

Therefore the PBT/vPvB assessment stops at this point.