3,3,4,4,5,5,6,6,6-nonafluorohexene

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Persistence (P)

Though not readily biodegradable, PFBE (3,3,4,4,5,5,6,6,6-nonafluorohexene) is not likely to persist in surface waters due to its low water solubility (15.6 mg/l), high vapour pressure (22kPa at 20°C) and estimated Henry's Law constant (3 - 100 atm.m3.mol-1). As a result, any releases of PFBE to the aquatic environment are likely to rapidly partition to atmosphere, and detectible concentrations in water will be hard to acheive. PFBE has only moderate affinity for soil (measured log Koc = 2.96 Koc = 903). Volatilisation from wet and dry soil surfaces is an important fate process for any releases, based on the estimated Henry's law constant and this compound's high vapour pressure. Consequently, any PFBE released into the environment is expected to partition almost entirely to the atmosphere, where it will quickly react with atmospheric hydoxyl radicals (°OH), with a short atmospheric lifetime, estimated to be 6.4 hours. Overall it is considered that PFBE will not be Persistent (P) or Very Persistent (vP).

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Bioaccumulation

The measured log Kow of 4.13 of PFBE is below the screening criteria of log Kow < 4.5. Therefore PFBE is considered not to be B or vB.

Toxicity (T)

PFBE (3,3,4,4,5,5,6,6,6-nonafluorohexene) showed no evidence of toxicity to fish, daphnia or algae at a maximum loading rate of 1000mg/l in well conducted short term tests. The methodology ensured the highest practicable concentrations of PFBE in water possible. Because of its high volatility and low water solubility such concentrations are unlikely to be achievable in the actual aquatic environment. The acute effect concentrations observed are much higher than the screening criterion of 1.0 mg/l. Further, it can be expected that the chronic effect concentrations for PFBE will be much higher than the screening criterion of 0.01 mg/l. In practice it is unlikely that PFBE would ever be found in environmental water in detectable concentrations. Therefore the chronic toxicity risk from PFBE is judged to be extremely low.

PFBE (3,3,4,4,5,5,6,6,6-nonafluorohexene) was not mutagenic both in the presence and absence of metabolic activation in a bacterial reverse mutation assay, an in-vitro chromosome aberration test and an in-vitro mammalian cell gene mutation assay. All tests were performed to OECD protocols and GLP standards. Therefore it is not classified for mutagenicity. No evidence of embryotoxicity or treatment related malformations were seen in the offspring of rats exposed by inhalation during days 6-15 of gestation to levels of PFBE (3,3,4,4,5,5,6,6,6-nonafluorohexene) of 1,000 or 70,000 ppm. PFBE is not classified as toxic for reproduction for developmental effects according to Directive 67/548/EEC.

No adverse effects were seen in rats exposed to 2000 ppm (20123 mg/m3) PFBE (3,3,4,4,5,5,6,6,6 -nonafluorohexene) in a 28 -day repeated inhalation study conducted to OECD Guideline 412. Therefore classification for STOT-RE is not warranted according to the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation EC No. 1272/2008 because toxic effects were only seen in rats exposed to concentrations well in excess of 3 mg/l (3000 mg/m3), 6 hr/day for 28 days. Based also on this study classification is not warranted according to EU directive 67/548/EEC (R48) because significant toxicity was only seen in the rat following exposure to concentrations well in excess of 0.25 mg/l (250 mg/m3), 6 hr/day for 28 days.

Therefore, PFBE is considered not to be T

Overall assessment.

PFBE is considered not to be PBT or vPvB.