Alkenes, C11-12

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

The criteria set out under REACH for determining whether a substance is PBT/vPvB are as follows:

 

Criterion	PBT criteria	vPvB criteria
P	Half-life (T½) > 60 d in marine water or Half-life (T½) > 40 d in fresh or estuarine water or Half-life (T½) > 180 d in marine sediment or Half-life (T½) > 120 d in fresh or estuarine water; sediment or Half-life (T½) in soil > 120 d	Half-life (T½) > 60 d in marine fresh or estuarine water or Half-life (T½) > 180 d in marine, fresh or estuarine water; sediment Half-life (T½) > 180 d in soil
B	BCF > 2000 L/kg in fresh or marine aquatic species	BCF > 5000 L/kg
T	Chronic NOEC < 0.01 mg/l for marine or freshwater organisms, or Substance is classified as carcinogenic (category 1 or 2), mutagenic (category 1 or 2), or toxic for reproduction (category 1, 2 or 3) or There is other evidence of chronic toxicity, as identified by the classifications: T, R48, or Xn, R48 according to Directive 67/548/EEC.	Not applicable
Note: (a) BCF is bioconcentration factor, NOEC is no-observed effect concentration and CMR is a substance classified as carcinogenic, mutagenic or toxic for reproduction (b) For marine environmental risk assessment, half-life data in freshwater sediment can be overruled by data obtained under marine conditions (c) Substances are classified when they fulfil the criteria for all three inherent properties for P, B and T. However, there is certain flexibility, for instance in cases where one criterion is marginally not fulfilled but the others are exceeded considerably.

 

The above criteria are the definitive criteria for PBT assessment and listed in Annex XIII of REACH. However, the first step in the PBT assessment is to conduct a screening assessment using screening criteria. Once this screening step is carried out it is possible to evaluate measured data against the definitive criteria listed above. If a substance is confirmed to be PBT/vPvB a third step is required to estimate the amounts of substance released to the different environmental compartments from all activities and uses.

 

8.1.1. Persistence (P) Assessment

One of the screening criteria for persistence is that if a substance is considered to be readily biodegradable the substance is screened as being not P and not vP. Category members with carbon numbers from C6 -24 have been shown to be readily biodegradable in biodegradation screening tests. Category members in this carbon number range are therefore not considered to meet the criteria for P or vP. However, category members with carbon number ranges above C24 cannot be ruled out from being P or vP, and so should be considered potentially P or vP.

 

8.1.2. Bioaccumulation (B) Assessment

The screening criterion for bioaccumulation is that a substance is not B or vB if it has a log Kow of <4.5. Only the C6 members of the category have measured log Kow below 4.5. All other category members have log Kow above 4.5 and therefore cannot be ruled out as being B or vB.

 

ECHA’s Guidance on Information Requirements and Chemical Safety Assessment - Part C: PBT Assessment (2008) states that the aquatic BCF of a substance is probably lower than 2000 L/kg if the calculated log Kow is higher than 10. Log Kow have been calculated in KOWWIN and SPARC. As none of the models have experimental data in this Kow range the reliability of modelled Kow values >10 is not known. However, as both models indicate that at C20 and above the log Kow >10 we can conclude that category members with carbon numbers above C20 are unlikely to meet the definitive criteria for B/vB.

Measured BCF are not available for any category member and so data cannot be compared to the definitive criteria given in REACH Annex XIII.

Category members with carbon numbers of C8 -C18 cannot be ruled out from being B or vB, and so should be considered potentially bioaccumulative (B) or very bioaccumulative (vB).

 

8.1.3. Toxicity (T) Assessment

8.1.3.1. Environmental Toxicity

 

The screening criteria for toxicity are that an acute EC50 or LC50 <0.1mg/l is considered to be T, and that an EC50 or LC50 <0.01mg/l indicates that the substance is definitely T. Acute ecotoxicity data are available for category members with carbon numbers in the range C6 -C24. The results indicate that acute effects <0.1mg/l are not expected for any category member.

A single chronic invertebrate study is available at C10. The NOEC from this study is 0.0194 mg/l. Again, this does not meet the criterion to be considered Toxic.

None of the category members are considered to meet the T criterion.

 

8.1.3.2. Human Health Hazards Assessment (T)

Category members do not fulfill the Toxicity criterion for human health.

 

8.1.4. Summary and overall Conclusions on PBT and vPvB properties

The screening assessment of the available data indicates that conclusion (ii) is appropriate for members of this category as stipulated below.

 

ii) The data show that the properties of the substance do not meet the specific criteria detailed in Annex XIII or do not allow a direct comparison with all the criteria in Annex XIII but nevertheless indicate that the substance would not have these properties and the substance is not considered a PBT/vPvB.

 

Exxon (2009) have also conducted a PBT assessment of higher olefins including branched, linear, alpha and internal with C6 to C19 carbons. Their assessment therefore covered a large portion of this category. Their conclusion was that none of the hydrocarbons were likely to be PBT or vPvB. 

 

Therefore the PBT/vPvB assessment stops at this point.