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EC number: 207-938-1 | CAS number: 502-44-3
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
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- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
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- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
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- Nanomaterial photocatalytic activity
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- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data

Endpoint summary
Administrative data
Link to relevant study record(s)
Description of key information
Short description of key information on bioaccumulation potential result:
E-caprolactone will be rapidly hydrolysed in the stomach or bloodstream
to form 6-hydroxyhexanoic acid.
The highly water-soluble hydrolysis product is predicted to be rapidly
excreted in the urine. No bioaccumulation is likely, however the
hydrolysis product may be incorporated into normal fatty acid metabolism.
Key value for chemical safety assessment
- Bioaccumulation potential:
- no bioaccumulation potential
Additional information
A theoretical assessment of the toxicokinetics of e-caprolactone indicates that the substance will be rapidly chemically or enzymically hydrolysed under physiological conditions (i.e. in the stomach or following absorption into the bloodstream) with the subsequent production of 6 -hydroxyhexanoic acid. The half-life of capa monomer in the stomach is approximately 0.4 hours (pH 1.2, temperature 37 C). Human serum paraoxonase (PON1) isozymes Q and R are able to hydrolyse lactone substances including e-caprolactone; half-lives of less than one minute are reported for struturally similar substances. The hydrolysis product is water soluble and expected to be distributed throughout the body and excreted rapidly in the urine. Bioaccumulation of the substance is not predicted. However it is theoretically possible that the hydrolysis product may be further metabolised and incorporated to some extent in metabolic pathways due to its structural similarity to endogenous fatty acids; this is not considered to represent bio-accumulation per se.
Discussion on bioaccumulation potential result:
No specific studies are required. According to Column 1 of Annex VIII of the REACH regulation, Assessment of the toxicokinetic behaviour of the substance (to the extent that can be derived from the relevant available information) is required and this is provided. An adequate assessment of the basic toxicokinetics of e-caprolactone can be made from the exisiting toxicity data and theoretical considerations, wtithout the need for specific testing.
Absorption
The substance will be rapidly hydrolysed in the stomach following oral administration (with a half-life of approximately 0.4 hours). The intact molecule satisifies Lipinski's rule of 5 (OECD QSAR Toolbox) and therefore is likely to be bioavailable, however absorption of the hydrolysis product is most likely. Absorption following inhalation is also likley to be extensive. Dermal absorption is likely to be less extensive, but is likely to occur to some extent as shown by the systemic toxicity in the acute dermal toxicity study.
Distribution
The intact substance is unlikely to be significantly distributed. Rapid hydrolysis in the stomach will limit absorption and any substance which is absorbed systemically is likely to be rapidly hydolysed by serum esterases; half-lives of <1 minute are reported for structurally similar compounds. The hydrolysis product 6 -hydroxyhexanoic acid is highly water soluble and therefore is likley to be rapidly and extensively distributed in the blood.
Metabolism
As discussed above, the substance will be hydrolysed rapidly either chemically (in the stomach) or enzymically (by serum esterases) to the hydrolysis product 6 -hydroxyhexanoic acid. The hydrolysis product is structurally similar to endogenous fatty acids and therefore may be incorporated into lipid metabolism pathways.
Excretion
Rapid urinary excretion of the highly-water soluble hydrolysis product is likely; no bioaccumulation is therefore predicted.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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