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EC number: 244-479-6 | CAS number: 21615-47-4
- 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
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- 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
Bioaccumulation: aquatic / sediment
Administrative data
Link to relevant study record(s)
- Endpoint:
- bioaccumulation in aquatic species: fish
- Type of information:
- read-across from supporting substance (structural analogue or surrogate)
- Remarks:
- Data from the different publications are compiled in this target entry.
- Adequacy of study:
- weight of evidence
- Justification for type of information:
- The study was performed for the corresponding acid (perfluorohexanoic acid) of the target substance ammonium undecafluorohexanoate. Due to the very low pKa value of 3.29 the anionic form of the acid is the predominant form in the environment. Thus, it is considered justified to use experimental data from the corresponding acid of the ammonium salt in order to assess the bioaccumulation potential of the target substance.
- Reason / purpose for cross-reference:
- read-across source
- Reason / purpose for cross-reference:
- read-across source
- Reason / purpose for cross-reference:
- read-across source
- Remarks on result:
- not measured/tested
- Remarks:
- The primary route of potential accumulation of perfluorinated compounds is not considerd to be the fat tissue. Thus, lipid normalization was not considered to be relevant for this study.; Data from publication Martin et al. 2003a
- Remarks on result:
- not measured/tested
- Remarks:
- Data from publication Martin et al. 2003b
- Remarks on result:
- not determinable
- Remarks:
- A BCF could not be determined since perfluorohexanoic acid could not be detected in carcass and liver samples. / Data from publication Yeung & Mabury, 2013
- Temp.:
- 12 °C
- Type:
- BCF
- Value:
- 4 L/kg
- Basis:
- whole body w.w.
- Calculation basis:
- steady state
- Remarks on result:
- other: Carcass analysis; Result for perfluorooctanoic acid (PFOA)
- Remarks:
- Data from publication Martin et al. 2003a
- Temp.:
- 12 °C
- Type:
- BCF
- Value:
- 27 L/kg
- Basis:
- whole body w.w.
- Calculation basis:
- steady state
- Remarks on result:
- other: Blood analysis; Result for perfluorooctanoic acid (PFOA)
- Remarks:
- Data from publication Martin et al. 2003a
- Temp.:
- 12 °C
- Type:
- BCF
- Value:
- 8 L/kg
- Basis:
- whole body w.w.
- Calculation basis:
- steady state
- Remarks on result:
- other: Liver analysis; Result for perfluorooctanoic acid (PFOA)
- Remarks:
- Data from publication Martin et al. 2003a
- Remarks on result:
- not determinable
- Remarks:
- A BAF could not be determined since perfluorohexanoic acid could not be detected in carcass and liver samples. / Data from publication Martin et al. 2003b
- Remarks on result:
- not determinable
- Remarks:
- A BCF could not be determined since perfluorohexanoic acid could not be detected in carcass and liver samples. / Data from publication Yeung & Mabury, 2013
- Elimination:
- yes
- Parameter:
- DT50
- Depuration time (DT):
- 5.2 d
- Remarks on result:
- other: Carcass analysis; Result for perfluorooctanoic acid (PFOA)
- Remarks:
- Data from publication Martin et al. 2003a
- Elimination:
- yes
- Parameter:
- DT50
- Depuration time (DT):
- 4.5 d
- Remarks on result:
- other: Blood analysis; Result for perfluorooctanoic acid (PFOA)
- Remarks:
- Data from publication Martin et al. 2003a
- Elimination:
- yes
- Parameter:
- DT50
- Depuration time (DT):
- 3.9 d
- Remarks on result:
- other: Liver analysis; Result for perfluorooctanoic acid (PFOA)
- Remarks:
- Data from publication Martin et al. 2003a
- Remarks on result:
- not determinable
- Remarks:
- A BAF could not be determined since perfluorohexanoic acid could not be detected in carcass and liver samples. / Data from publication Martin et al. 2003b
- Remarks on result:
- not determinable
- Remarks:
- A BCF could not be determined since perfluorohexanoic acid could not be detected in carcass and liver samples. / Data from publication Yeung & Mabury, 2013
- Rate constant:
- overall uptake rate constant (L kg-1 d-1)
- Value:
- 0.53
- Remarks on result:
- other: Carcass analysis; Result for perfluorooctanoic acid (PFOA)
- Remarks:
- Data from publication Martin et al. 2003a
- Rate constant:
- overall uptake rate constant (L kg-1 d-1)
- Value:
- 4.1
- Remarks on result:
- other: Blood analysis; Result for perfluorooctanoic acid (PFOA)
- Remarks:
- Data from publication Martin et al. 2003a
- Rate constant:
- overall uptake rate constant (L kg-1 d-1)
- Value:
- 1.4
- Remarks on result:
- other: Liver analysis; Result for perfluorooctanoic acid (PFOA)
- Remarks:
- Data from publication Martin et al. 2003a
- Rate constant:
- overall depuration rate constant (d-1)
- Value:
- 130
- Remarks on result:
- other: Carcass analysis; Result for perfluorooctanoic acid (PFOA)
- Remarks:
- Data from publication Martin et al. 2003a
- Rate constant:
- overall depuration rate constant (d-1)
- Value:
- 150
- Remarks on result:
- other: Blood analysis; Result for perfluorooctanoic acid (PFOA)
- Remarks:
- Data from publication Martin et al. 2003a
- Rate constant:
- overall depuration rate constant (d-1)
- Value:
- 180
- Remarks on result:
- other: Liver analysis; Result for perfluorooctanoic acid (PFOA)
- Remarks:
- Data from publication Martin et al. 2003a
- Remarks on result:
- not determinable
- Remarks:
- A BAF could not be determined since perfluorohexanoic acid could not be detected in carcass and liver samples. / Data from publication Martin et al. 2003b
- Remarks on result:
- not determinable
- Remarks:
- A BCF could not be determined since perfluorohexanoic acid could not be detected in carcass and liver samples. / Data from publication Yeung & Mabury, 2013
- Metabolites:
- Metabolites were not analysed since perfluorinated acids are considered to be stable. No metabolism is expected.
- Endpoint:
- bioaccumulation in aquatic species: fish
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- study well documented, meets generally accepted scientific principles, acceptable for assessment
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- - Principle of test: Tissue distribution and bioconcentration study with rainbow trout (Oncorhynchus mykiss) exposed simultaneously to a suite of perfluoroalkyl carboxylates and sulfonates of varying fluorinated chain lengths in a flow-through aqueous exposure. The compound-specific bioaccumulation parameters were determined by liquid chromatography–tandem mass spectrometry (LC-MS-MS).
- Short description of test conditions: Juvenile rainbow trout were exposed to a 1,000-fold dilution of the stock perfluorinated acids (PFAs: C5 - C14) solution in a flow-through exposure design for 12 d, followed by 33 d of depuration in clean water. Fish growth was monitored by weighing the total biomass. Three fish from the exposure tank and one from the control tank were sampled at each predetermined interval during the uptake phase of the experiment (4.5, 9, 18, 36, 72, 144, and 288 h). At 288 h, the remaining fish were transferred to new aquaria receiving clean water. During the depuration phase, three fish from the treatment tank and one from the control tank were sampled at each time interval (4.5, 9, 18, 36, 72, 144, 288, 456, and 792 h). During the uptake phase, water samples were collected below the surface at 0.25, 4.5, 12, 18, 36, 72, 144, 197, 244, and 288 h. Water samples were also collected at 48 and 96 h of the depuration phase from both tanks to check for contamination. Sampled fish were anesthetized. The gut, consisting of esophagus, stomach, pyloric ceca, spleen, and intestines, was removed but not analyzed. The blood, liver, and carcass samples were analyzed separately for PFAs at each sampling time to determine the kinetics of uptake and depuration. - GLP compliance:
- no
- Radiolabelling:
- no
- Details on sampling:
- - Sampling intervals/frequency for test organisms: 4.5, 9, 18, 36, 72, 144, and 288 h (uptake phase), 4.5, 9, 18, 36, 72, 144, 288, 456, and 792 h (depuration phase)
- Sampling intervals/frequency for test medium samples: 0.25, 4.5, 12, 18, 36, 72, 144, 197, 244, and 288 h (water samples, uptake phase), 48 and 96 h (depuration phase)
- Details on sampling and analysis of test organisms and test media samples (e.g. sample preparation, analytical methods): Sampled fish were anesthetized. The gut, consisting of esophagus, stomach, pyloric ceca, spleen, and intestines, was removed but not analyzed. The blood, liver, and carcass samples were analyzed separately for PFAs at each sampling time to determine the kinetics of uptake and depuration. Liver and blood samples were homogenized in 15-mL plastic (polypropylene copolymer) centrifuge tubes containing 3 mL of Na2CO3 (0.25 M), 1 mL of water, 1 mL of the ion-pairing agent tetrabutylammonium hydrogensulfate (0.5 M adjusted to pH 10), and 100 mL (25 ng) of the internal standard, perfluorononanoic acid (PFNA, C9). Carcass samples were first reduced to a fine powder by using a mortar and pestle with liquid nitrogen, and subsequently were homogenized in 50-mL plastic centrifuge tubes containing 10 to 20 mL of Na2CO3. An exact quantity (2–4 g) of the homogenate was then transferred to a separate centrifuge tube containing 1 mL of water, 1 mL of tetrabutylammonium hydrogensulfate, and 100 mL of PFNA. - Vehicle:
- yes
- Remarks:
- methanol
- Details on preparation of test solutions, spiked fish food or sediment:
- PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution containing all the test compounds was produced by first dissolving PFAs in a small amount of methanol, which subsequently was dissolved in 30 L of reverse osmosis laboratory water. The resulting solution was contained in a polypropylene container and was stirred for 3 d before the beginning of the experiment. After allowing the solution to settle for several hours, some of the test compounds had not completely dissolved, based on the appearance of a white solid at the surface of the solution. This material was removed by filtering the entire solution through glass (GF/C) microfiber filters (Whatman, Kent, UK). The resulting solution was used for exposure and was constantly stirred while being delivered to exposure tanks.
- Controls: yes, test medium control
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): methanol - Test organisms (species):
- Oncorhynchus mykiss (previous name: Salmo gairdneri)
- Details on test organisms:
- TEST ORGANISM
- Common name: rainbow trout
- Source: Rainbow springs (Thamesford, Ontario, Canada)
- Age at study initiation (mean and range, SD): juvenile fish
- Weight at study initiation (mean and range, SD): 5-10 g (mean: 7.3 g for exposure and 7.9 g for control)
- Health status: Only healthy fish were used.
- Description of housing/holding area:
- Feeding during test
- Food type: Trout feed was purchased from Martin Mills (Thamesford, Ontario, Canada)
- Amount&Frequency: Fish were fed daily at a rate of 1.5% body weight per day, corrected for growth throughout the experiment.
ACCLIMATION
- Acclimation period: 2 weeks
- Acclimation conditions (same as test or not): same as test
- Type and amount of food: same as test - Route of exposure:
- aqueous
- Justification for method:
- aqueous exposure method used for following reason: The test item is well soluble in water and has a low potential to adsorb to sediment or food particles.
- Test type:
- flow-through
- Water / sediment media type:
- natural water: freshwater
- Total exposure / uptake duration:
- 12 d
- Total depuration duration:
- 33 d
- Test temperature:
- 12 °C
- Details on test conditions:
- TEST SYSTEM
- Test vessel: glass aquaria lined with polypropylene bags (Volume: 45 L)
- Type of flow-through (e.g. peristaltic or proportional diluter): proportional diluter
- Renewal rate of test solution (frequency/flow rate): 500 mL dilution water/min; 0.5 mL test substance/min
- No. of organisms per vessel: no information given; three fish were sampled at each timepoint
- No. of vessels per concentration (replicates): 1
- No. of vessels per control / vehicle control (replicates): 1
- Biomass loading rate: 8 g/L (exposure), 2.5 g/L (control)
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Carbon-filtered and dechlorinated water (with Na2SO3)
- Holding medium different from test medium: no, same as test
OTHER TEST CONDITIONS
- Photoperiod: 12 h light / 8 h darkness - Nominal and measured concentrations:
- Measured: 0.014 - 1.7 µg/L (for individual components; mixture of perfluorinated acids was tested); perfulorohexanoic acid was present in the test vessels at concentrations of 1.7 µg/L (RSD: 10%).
- Reference substance (positive control):
- no
- Remarks on result:
- not measured/tested
- Remarks:
- The primary route of potential accumulation of perfluorinated compounds is not considerd to be the fat tissue. Thus, lipid normalization was not considered to be relevant for this study.
- Temp.:
- 12 °C
- Type:
- BCF
- Value:
- 4 L/kg
- Basis:
- whole body w.w.
- Calculation basis:
- steady state
- Remarks on result:
- other: Carcass analysis; Result for perfluorooctanoic acid (PFOA)
- Temp.:
- 12 °C
- Type:
- BCF
- Value:
- 27 L/kg
- Basis:
- whole body w.w.
- Calculation basis:
- steady state
- Remarks on result:
- other: Blood analysis; Result for perfluorooctanoic acid (PFOA)
- Temp.:
- 12 °C
- Type:
- BCF
- Value:
- 8 L/kg
- Basis:
- whole body w.w.
- Calculation basis:
- steady state
- Remarks on result:
- other: Liver analysis; Result for perfluorooctanoic acid (PFOA)
- Elimination:
- yes
- Parameter:
- DT50
- Depuration time (DT):
- 5.2 d
- Remarks on result:
- other: Carcass analysis; Result for perfluorooctanoic acid (PFOA)
- Elimination:
- yes
- Parameter:
- DT50
- Depuration time (DT):
- 4.5 d
- Remarks on result:
- other: Blood analysis; Result for perfluorooctanoic acid (PFOA)
- Elimination:
- yes
- Parameter:
- DT50
- Depuration time (DT):
- 3.9 d
- Remarks on result:
- other: Liver analysis; Result for perfluorooctanoic acid (PFOA)
- Rate constant:
- overall uptake rate constant (L kg-1 d-1)
- Value:
- 0.53
- Remarks on result:
- other: Carcass analysis; Result for perfluorooctanoic acid (PFOA)
- Rate constant:
- overall uptake rate constant (L kg-1 d-1)
- Value:
- 4.1
- Remarks on result:
- other: Blood analysis; Result for perfluorooctanoic acid (PFOA)
- Rate constant:
- overall uptake rate constant (L kg-1 d-1)
- Value:
- 1.4
- Remarks on result:
- other: Liver analysis; Result for perfluorooctanoic acid (PFOA)
- Rate constant:
- overall depuration rate constant (d-1)
- Value:
- 130
- Remarks on result:
- other: Carcass analysis; Result for perfluorooctanoic acid (PFOA)
- Rate constant:
- overall depuration rate constant (d-1)
- Value:
- 150
- Remarks on result:
- other: Blood analysis; Result for perfluorooctanoic acid (PFOA)
- Rate constant:
- overall depuration rate constant (d-1)
- Value:
- 180
- Remarks on result:
- other: Liver analysis; Result for perfluorooctanoic acid (PFOA)
- Metabolites:
- Metabolites were not analysed since perfluorinated acids are considered to be stable. No metabolism is expected.
- Details on results:
- - Mortality of test organisms: 2% in exposure tank, 0% in control
- Observations on body length and weight: A growth rate of 4.9E-03 g/d was determined in the exposure tank and 5.1E-03 g/d in the control.
- Organ specific bioaccumulation: In general, PFA concentrations were greatest in the blood, kidney, liver, gall bladder, and lowest in the gonads, adipose and muscle tissue. Within the blood, the plasma contained between 94 and 99% of total PFAs, with only a minor fraction detectable in the cellular fraction. Perfluorinated acids were also detectable in the gills. - Endpoint:
- bioaccumulation in aquatic species: fish
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- study well documented, meets generally accepted scientific principles, acceptable for assessment
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- - Principle of test: Juvenile rainbow trout (Oncorhynchus mykiss) were simultaneously exposed to a homologous series of perfluoroalkyl carboxylates and sulfonates for 34 d in the diet, followed by a 41 d depuration period. Carcass and liver concentrations were determined by using liquid chromatography–tandem mass spectrometry, and kinetic rates were calculated to determine compound specific bioaccumulation parameters.
- Short description of test conditions: Fish were fed with treated food during uptake phase for 34 d and untreated food during depuration phase for 41 d. For analysis, fish were sampled on days 4, 7, 14, 21, 28, and 34 (uptake) and 7, 14, 21, 28, 34, and 41 (depuration) and concentrations were analysed in carcass and liver.
- Parameters analysed / observed: Concentration of perfluoroalkyl carboxylates and sulfonates was analysed in different compartments (carcass, liver) of fish during uptake and depuration phase. Growth rate, mortality, bioaccumulation factor (BAF), feeding rate, assimilation efficiency and depuration half life were determined. - GLP compliance:
- no
- Radiolabelling:
- no
- Details on sampling:
- - Sampling intervals/frequency for test organisms: Fish were sampled on days 4, 7, 14, 21, 28, and 34 during uptake phase and 7, 14, 21, 28, 34, and 41 during depuration phase.
- Sampling intervals/frequency for test medium samples: same as for test organisms
- Details on sampling and analysis of test organisms and test media samples (e.g. sample preparation, analytical methods): Fish were always sampled before feeding and approximately 24 h after the previous feeding. Sampled fish were anesthetized with MS-222 and euthanized by a blow to the head and cervical dislocation. An incision was made along the ventral surface from the anus to the gills, and the entire liver was removed. The gut, consisting of esophagus, stomach, pyloric ceca, spleen, and intestines, was removed to avoid contamination of the carcass sample with feces and unabsorbed food. The resulting liver and carcass samples were analyzed separately throughout the experiment to determine the kinetics of uptake and depuration. - Vehicle:
- yes
- Remarks:
- methanol (evaporated before addition of spiked food)
- Details on preparation of test solutions, spiked fish food or sediment:
- PREPARATION OF SPIKED FISH FOOD
- Spiked food was prepared by adding starter food (Martin Mills, Tavistock, ON, Canada) to a round-bottom flask containing a solution of all the test compounds in methanol. The flask was placed on a rotary evaporator and the mixture was slowly dried under vacuum. The resulting spiked food was further dried in an oven at 60 °C for 3 h to remove excess methanol. Control food was prepared in the same manner; minus test compounds. - Test organisms (species):
- Oncorhynchus mykiss (previous name: Salmo gairdneri)
- Details on test organisms:
- TEST ORGANISM
- Common name: rainbow trout
- Source: purchased from Rainbow Springs (Thamesford, ON, Canada)
- Age at study initiation (mean and range, SD): juvenile fish
- Weight at study initiation (mean and range, SD): 2-5 g
- Health status: only healthy fish were used
- Description of housing/holding conditions: Carbon-filtered and dechlorinated water (with Na2SO3) flowed through each tank at 2 L/min, the temperature was maintained at 12 °C, and a 12-h photoperiod.
- Feeding during test
- Food type: spiked food
- Amount: at a rate of 1.5% body weight
- Frequency: daily
ACCLIMATION
- Acclimation period: two weeks
- Acclimation conditions (same as test or not): same as test
- Type and amount of food: commercial trout food (Martin Mills, Tavistock, Ontario, Canada) - Route of exposure:
- feed
- Justification for method:
- dietary exposure method used for following reason: Bioaccumulation via the dietary route was performed in addition to the aqueous route.
- Test type:
- flow-through
- Water / sediment media type:
- natural water: freshwater
- Total exposure / uptake duration:
- 34 d
- Total depuration duration:
- 41 d
- Test temperature:
- 12 °C
- Details on test conditions:
- TEST SYSTEM
- Test vessel: not specified
- Renewal rate of test solution (frequency/flow rate): 2 L/min
- No. of organisms per vessel: not specified
- No. of vessels per concentration (replicates): 2 vessels
- No. of vessels per control / vehicle control (replicates): 1 vessel
- Biomass loading rate: 2.0 - 2.2 g/L (control: 1.1 g/L)
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Carbon-filtered and dechlorinated water (with Na2SO3)
- Holding medium different from test medium: same as test
OTHER TEST CONDITIONS
- Photoperiod: 12 h light / 12 h darkness
- For dietary exposure fish bioaccumulation, overall daily feeding rate used in the study: 1.5% d
- For dietary exposure fish bioaccumulation, number of feeds per day (number of feeds daily ration split between): Fish were fed daily - Nominal and measured concentrations:
- Concentration of perfluorohexanoic acid in food: 0.52 µg/g
- Reference substance (positive control):
- no
- Remarks on result:
- not measured/tested
- Remarks on result:
- not determinable
- Remarks:
- A BAF could not be determined since perfluorohexanoic acid could not be detected in carcass and liver samples.
- Remarks on result:
- not determinable
- Remarks:
- A BAF could not be determined since perfluorohexanoic acid could not be detected in carcass and liver samples.
- Remarks on result:
- not determinable
- Remarks:
- A BAF could not be determined since perfluorohexanoic acid could not be detected in carcass and liver samples.
- Metabolites:
- Not analysed since perfluorinated compounds are known to be stable to transformation and degradation.
- Details on results:
- - Mortality of test organisms: 0% in contol and treatments
- Observations on feeding behavior: Feeding rate was 1.5% of body weight fed daily (g food/g fish/d)
- Observations on body length and weight: No statistically significant difference was found in the rate of growth for exposed fish relative to controls. - Endpoint:
- bioaccumulation in aquatic species: fish
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- study well documented, meets generally accepted scientific principles, acceptable for assessment
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- - Principle of test: The bioconcentration of perfluoroalkylates in juvenile rainbow trout was studied. Fish were exposed to two aqueous film-forming foams (AFFF) under flow-through conditions. During uptake phase three fish were samples on day 1, 3, 6 and 11. During depuration phase fish were sampled on day 3, 7, 13 and 25. Liver and carcass homogenates were analyzed by LC-MS/MS for twenty perfluoroalkylates including perfluorohexanoic acid.
- GLP compliance:
- no
- Remarks:
- Publication
- Radiolabelling:
- no
- Details on sampling:
- - Sampling intervals/frequency for test organisms: During uptake phase three fish were samples on day 1, 3, 6 and 11. During depuration phase three fish were sampled on day 3, 7, 13 and 25.
- Sampling intervals/frequency for test medium samples: Water samples were taken at the same time as fish samples.
- Sample storage: The fish samples were subsequently kept frozen, and the water samples were stored at 4 °C until analysis.
- Details on sampling and analysis of test organisms and test media samples (e.g. sample preparation, analytical methods): Fish were euthanized using a lethal dose of 100 mg/mL of tricaine methane sulfonate and were briefly washed with Milli-Q water, dried with paper towel, and weighed. The liver was removed, and then it and the rest of the carcass were homogenized separately using a blender. - Vehicle:
- no
- Details on preparation of test solutions, spiked fish food or sediment:
- PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution with commercially available foam solutions was prepared and administered to the exposure tanks at 1 mL/min to give a final concentration of 1000 µg/L.
- Controls: yes, test medium control - Test organisms (species):
- Oncorhynchus mykiss (previous name: Salmo gairdneri)
- Details on test organisms:
- TEST ORGANISM
- Common name: rainbow trout
- Source: Humber Springs Trout Hatchery (Orangeville, Ontario, Canada)
- Age at study initiation (mean and range, SD): juvenile
- Weight at study initiation (mean and range, SD): 5−7 g
- Feeding during test
- Food type: commercial fish food
- Amount: 1.5% of body weight
- Frequency: daily
ACCLIMATION
- Acclimation period: 2 weeks prior to exposure
- Acclimation conditions (same as test or not): same as test - Route of exposure:
- aqueous
- Justification for method:
- aqueous exposure method used for following reason: The test item is well soluble in water and has a low potential to adsorb to sediment or food particles.
- Test type:
- flow-through
- Water / sediment media type:
- natural water: freshwater
- Total exposure / uptake duration:
- 11 d
- Total depuration duration:
- 36 d
- Test temperature:
- approx. 18 °C
- Details on test conditions:
- TEST SYSTEM
- Test vessel: 475 L fiberglass tanks
- Type of flow-through (e.g. peristaltic or proportional diluter): not specified
- Renewal rate of test solution (frequency/flow rate): approx. 10 L/min
- No. of organisms per vessel: not specified (three fish were sampled at each sampling point)
- No. of vessels per concentration (replicates): 1
- No. of vessels per control / vehicle control (replicates): 1
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: carbon filtered and dechlorinated tap water
- Holding medium different from test medium: same as test
OTHER TEST CONDITIONS
- Photoperiod: 12 h light/12 h dark - Nominal and measured concentrations:
- Measured: 44 ± 16 ng/L (perfluorohexanoic acid)
- Reference substance (positive control):
- no
- Remarks on result:
- not measured/tested
- Remarks on result:
- not determinable
- Remarks:
- A BCF could not be determined since perfluorohexanoic acid could not be detected in carcass and liver samples.
- Remarks on result:
- not determinable
- Remarks:
- A BCF could not be determined since perfluorohexanoic acid could not be detected in carcass and liver samples.
- Remarks on result:
- not determinable
- Remarks:
- A BCF could not be determined since perfluorohexanoic acid could not be detected in carcass and liver samples.
- Metabolites:
- Not analysed since perfluorinated compounds are known to be stable to transformation and degradation.
- Details on results:
- - Mortality of test organisms: 0% mortality
- Other biological observations: No increase in hepatosomatic index was recorded indicating that fish were not under metabolic stress from chemical exposure.
- Mortality and/or behavioural abnormalities of control: 0% mortality
- Observations on fish weight: Fish weight increased at the end of exposure: Control 9.5 ± 0.2 g (test start), 13.8 ± 0.9 g (test end); 3M foam 8.5 ± 0.3 g (test start), 14.4 ± 0.5 g (test end); Angus fire 8.7±0.5 g (test start), 14.8 ± 0.8 g (test end) - Reported statistics:
- A nonparametric Mann−Whitney U test was used to evaluate any significant difference in the growth rate or the hepatosomatic index between the treatment and the control groups. The significance level was α = 0.05.
- Endpoint:
- bioaccumulation in aquatic species: fish
- Remarks:
- Uptake of the substance in fish was measured.
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Study period:
- 27 Sep - 03 Oct 2018
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- study well documented, meets generally accepted scientific principles, acceptable for assessment
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- The study was conducted in referece to: Nawaji, T., Mizoguchi, N., Ono, M., Matuura, T., Seki, M., Teraoka, H. (2018): Comparing time-series of chemical concentrations in zebrafish (Danio rerio) embryos/larvae exposed to teratogens with different hydrophobicity; caffeine, sodium valproate, and diethylstilbestrol. J. Toxicol. Sci., 43, 267-273.
- GLP compliance:
- no
- Remarks:
- This study was not initially performed for REACh purposes but for other regulatory programs where the studies are not needed to be in compliance with GLP.
- Radiolabelling:
- no
- Details on sampling:
- - Sampling intervals/frequency for test organisms: All test levels were measured at test start and test end.
- Sampling intervals/frequency for test medium samples: Every 24 h fish were analyzed for concentration of test item.
- Details on sampling and analysis of test organisms and test media samples (e.g. sample preparation, analytical methods): The test samples were diluted with an appropriate amount of test water in advance. The larvae and embryos were first washed with clean dechlorinated tap water (4 times) and transferred to 1.5 mL sampling tubes. Afterwards 100 µL methanol/ultrapure water (1/1 v/v) was added and the sample was homogenized with an electric homogenizer for about 1 min. 300 µL methanol/ultrapure water (1/1 v/v) was added followed by centrifugation (20000xg for 10 min). The supernatant was processed and filled up to 1 mL with methanol/ultrapure water (1/1 v/v) and filtered with a membrane filer (Millex-LG, pore size 0.20 µm). 80 µL of the filtrate was taken, 80 µL methanol/ultrapure water (1/1 v/v) was added and vortexed for 10 sec. This sample was processed by analytical methods. - Vehicle:
- no
- Details on preparation of test solutions, spiked fish food or sediment:
- PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The weighed test sample (0.50 g) and 1 L dilution water were mixed, stirred and dissolved to prepare a stock solution of 500 mg/L. The stock solution was used to prepare the respective test solutions.
- Controls: yes, dilution water - Test organisms (species):
- Danio rerio (previous name: Brachydanio rerio)
- Details on test organisms:
- TEST ORGANISM
- Common name: zebrafish
- Strain: NIES-R
- Source: Originally supplied by National Institute for Environmental Studies, Japan
- Health status: only healthy fish were used
- Feeding during test : No feeding
ACCLIMATION FOR SPAWNING
- Acclimation conditions (same as test or not): same as test
- Type and amount of food: every day fed with appropriate amount of food (Artemia nauplii)
PAIRING AND COLLECTION OF FERTILIZED EGGS
- Two males and on female per container (approx. 3 L); no feeding during pairing. Fertilized eggs were collected from three breeding groups. Eggs were within 5 h after fertilization. - Route of exposure:
- aqueous
- Justification for method:
- aqueous exposure method used for following reason: Substance is sufficiently stable in water and the potential for adsorption is low. Thus, concentrations can be sufficiently maintained.
- Test type:
- static
- Water / sediment media type:
- natural water: freshwater
- Total exposure / uptake duration:
- 6 d
- Test temperature:
- 28.6 - 28.7 °C
- pH:
- 7.7
- Dissolved oxygen:
- 7.3 - 7.4 mg/L
- Details on test conditions:
- TEST SYSTEM
- Test vessel: 500 mL glass tanks (for exposure), 24-well plates for observation of symptoms
- Aeration: no
- No. of organisms per vessel: 24 (morphological observations); 45 per replicate/test level (180 in total)
- No. of vessels per concentration (replicates): 4 per test level (for measuring concentration in embryos/larvae); 24 per test level (for observation of symptoms)
- No. of vessels per control / vehicle control (replicates): 2
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted water (ISO 6341-1982)
- Holding medium different from test medium: same as test
OBSERVATIONS DURING TEST
- Observation of test organisms (mortaliy, malformation and oter visible abnormalities were observed every 24 h.
- Body weight was measured every 24 h
- Appearance of test solutions was checked at test start and end.
- Test item concentrations in embryo/larvae + test medium was measured.
OTHER TEST CONDITIONS
- Adjustment of pH: not adapted
- Photoperiod: 16 h light/8 h darkness
- Nominal and measured concentrations:
- Nominal: 100, 250, 500 mg/L
Measured: 101, 255, 511 mg/L (geometric mean) - Reference substance (positive control):
- no
- Remarks on result:
- not measured/tested
- Remarks on result:
- not measured/tested
- Remarks on result:
- other:
- Remarks:
- See "Any other information on results incl. tables"
- Remarks on result:
- not measured/tested
- Validity criteria fulfilled:
- not applicable
Referenceopen allclose all
All tissue concentrations were corrected for growth dilution by determining the percent increase in freshweight at each sampling interval, relative to t = 0, by using the predicted exponential growth rate equation.
Perfluorohexanoic acid (C6) could not be detected in the analysed tissues. Thus, the results for the perfluorinated acids >C6 are presented only. It can be concluded that perfuloroheaxanoic acid does not bioaccumulate in the analysed tissues.
Table 1: Bioconcentration factors in carcass for all perfluorinated acids found
Compound |
BCF [L/kg] |
Perfluorooctanoic acid (PFOA:C8) |
4.0 ± 0.6 |
Perfluorodecanoic acid (PFDA:C10) |
450 ± 62 |
Perfluoroundecanoic acid (PFUnA:C11) |
2700 ± 400 |
Perfluorododecanoic acid (PFDoA:C12) |
18000 ± 2700 |
Perfluorotetradecanoic acid (PFTA:C13) |
23000 ± 5300 |
Table 2: Bioconcentration factors in blood for all perfluorinated acids found
Compound |
BCF [L/kg] |
Perfluorooctanoic acid (PFOA:C8) |
27 ± 9.7 |
Perfluorodecanoic acid (PFDA:C10) |
2700 ± 350 |
Perfluoroundecanoic acid (PFUnA:C11) |
11000 ± 1400 |
Perfluorododecanoic acid (PFDoA:C12) |
40000 ± 4500 |
Perfluorotetradecanoic acid (PFTA:C13) |
30000 ± 4200 |
Table 3: Bioconcentration factors in liver for all perfluorinated acids found
Compound |
BCF [L/kg] |
Perfluorooctanoic acid (PFOA:C8) |
8.0 ± 0.59 |
Perfluorodecanoic acid (PFDA:C10) |
1100 ± 180 |
Perfluoroundecanoic acid (PFUnA:C11) |
4900 ± 770 |
Perfluorododecanoic acid (PFDoA:C12) |
18000 ± 2900 |
Perfluorotetradecanoic acid (PFTA:C13) |
30000 ± 6000 |
Water samples collected before and after feeding revealed no trace of PFAs (≤ 5 ng/L), indicating negligible transfer of contaminants to the water column during the feeding process. Only carboxylates with more than six perfluoroalkyl carbons and sulfonates with more than four perfluoroalkyl carbons were detectable in fish tissues at all given sampling times. At any time during the experiment, perfluoropentanoic acid, perfluorohexanoic acid (PFHxA, C10), and perfluoroheptanoic acid (PFHpA, C7) were not detected, thus, their bioaccumulation potential was expected to be negligible (i.e., BAF < 0.1).
Perfluorohexanoic acid could not be detected in fish samples.
Mortality
No mortality was recorded.
Morphology
No morphological abnormalities were recorded.
Table 1: Concentrations in test medium
Nominal concentration [mg/L] |
Measured concentration [mg/L] |
||
|
Test start |
Test end |
Geometric mean |
Control |
Not detected |
Not detected |
- |
100 |
101 |
101 |
101 |
250 |
254 |
256 |
255 |
500 |
501 |
522 |
511 |
Table 2: Concentrations in embryos/larvae (amount per embryo/larvae)
Nominal concentration [mg/L] |
Replicate |
24 h |
48 h |
72 h |
96 h |
120 h |
144 h |
||||||||||||
Conc. [ng/embryo or larvae] |
Mean |
S.D. |
Conc. [ng/embryo or larvae] |
Mean |
S.D. |
Conc. [ng/embryo or larvae] |
Mean |
S.D. |
Conc. [ng/embryo or larvae] |
Mean |
S.D. |
Conc. [ng/embryo or larvae] |
Mean |
S.D. |
Conc. [ng/embryo or larvae] |
Mean |
S.D. |
||
Control |
1 |
n.d. |
- |
- |
n.d. |
- |
- |
n.d. |
- |
- |
n.d. |
- |
- |
n.d. |
- |
- |
n.d. |
- |
- |
2 |
n.d. |
- |
- |
n.d. |
- |
- |
n.d. |
- |
- |
n.d. |
- |
- |
n.d. |
- |
- |
n.d. |
- |
- |
|
100 |
1 |
2.42 |
2.43 |
0.19 |
17.7 |
24.4 |
5.6 |
22.9 |
20.4 |
2.9 |
26.7 |
31.5 |
5.2 |
23.1 |
19.2 |
3.4 |
12.0 |
12.7 |
2.2 |
2 |
2.43 |
21.8 |
21.2 |
27.4 |
21.0 |
11.0 |
|||||||||||||
3 |
2.20 |
28.2 |
21.3 |
35.0 |
15.6 |
15.9 |
|||||||||||||
4 |
2.67 |
29.8 |
16.2 |
36.8 |
17.3 |
12.0 |
|||||||||||||
250 |
1 |
4.31 |
4.34 |
0.14 |
19.5 |
29.8 |
9.3 |
28.9 |
33.5 |
7.4 |
39.4 |
44.1 |
6.0 |
16.6 |
16.5 |
2.2 |
9.85 |
11.6 |
1.2 |
2 |
4.20 |
28.8 |
44.0 |
49.2 |
14.8 |
12.3 |
|||||||||||||
3 |
4.32 |
42.2 |
27.9 |
49.3 |
14.9 |
12.0 |
|||||||||||||
4 |
4.53 |
28.9 |
33.2 |
38.4 |
19.6 |
12.5 |
|||||||||||||
500 |
1 |
5.74 |
5.77 |
0.09 |
38.0 |
36.8 |
3.3 |
41.7 |
37.0 |
6.7 |
58.8 |
50.5 |
6.3 |
42.0 |
43.4 |
1.6 |
20.3 |
24.0 |
8.2 |
2 |
5.66 |
37.3 |
43.3 |
51.8 |
44.9 |
22.9 |
|||||||||||||
3 |
5.86 |
32.0 |
33.9 |
44.5 |
44.8 |
35.7 |
|||||||||||||
4 |
5.82 |
39.8 |
29.0 |
46.9 |
42.1 |
17.0 |
Table 3: Concentrations of test item (amount per body weight)
Nominal concentration [mg/L] |
Replicate |
24 h |
48 h |
72 h |
96 h |
120 h |
144 h |
||||||||||||
Conc. [mg/kg] |
Mean |
S.D. |
Conc. [mg/kg] |
Mean |
S.D. |
Conc. [mg/kg] |
Mean |
S.D. |
Conc. [mg/kg] |
Mean |
S.D. |
Conc. [mg/kg] |
Mean |
S.D. |
Conc. [mg/kg] |
Mean |
S.D. |
||
Control |
1 |
n.d. |
- |
- |
n.d. |
- |
- |
n.d. |
- |
- |
n.d. |
- |
- |
n.d. |
- |
- |
n.d. |
- |
- |
2 |
n.d. |
- |
- |
n.d. |
- |
- |
n.d. |
- |
- |
n.d. |
- |
- |
n.d. |
- |
- |
n.d. |
- |
- |
|
100 |
1 |
9.36 |
9.39 |
0.74 |
63.2 |
87.0 |
20.1 |
74.9 |
66.7 |
9.5 |
86.2 |
102 |
17 |
70.1 |
58.5 |
10.3 |
37.0 |
39.3 |
6.7 |
2 |
9.39 |
78.0 |
69.4 |
88.4 |
63.8 |
34.0 |
|||||||||||||
3 |
8.51 |
101 |
69.6 |
113 |
47.5 |
49.1 |
|||||||||||||
4 |
10.3 |
106 |
52.9 |
119 |
52.5 |
36.9 |
|||||||||||||
250 |
1 |
16.6 |
16.8 |
0.5 |
69.7 |
107 |
33 |
94.5 |
109 |
24 |
127 |
142 |
19 |
50.6 |
50.1 |
6.8 |
30.4 |
36.0 |
3.8 |
2 |
16.2 |
103 |
144 |
159 |
44.9 |
38.0 |
|||||||||||||
3 |
16.7 |
151 |
91.1 |
159 |
45.4 |
37.0 |
|||||||||||||
4 |
17.5 |
103 |
108 |
124 |
59.6 |
38.5 |
|||||||||||||
500 |
1 |
22.2 |
22.3 |
0.3 |
136 |
131 |
12 |
136 |
121 |
22 |
190 |
163 |
20 |
128 |
132 |
5 |
62.7 |
74.0 |
25.3 |
2 |
21.9 |
133 |
142 |
167 |
136 |
70.8 |
|||||||||||||
3 |
22.6 |
114 |
111 |
144 |
136 |
110 |
|||||||||||||
4 |
22.5 |
142 |
94.6 |
151 |
128 |
52.4 |
The concentration of test item in all exposure levels reached maximum values at 96 hpf (hours post fertilization) and then gradually decreased to less than half the corresponding maximum concentrations.
The temporal behavior was similar to data of diethylstilbestrol (DES) previously reported (Nawaji et al., 2018). According to the report, DES is highly soluble in fat and it was considered that and the gradual decrease of concentrations of DES in embryos/larvae was due to a decline of total lipid concentration in whole embryos/larvae because of the energetic costs of development and growth. Although the test item is an ammonium salt and has a high water solubility the amphipathic property of the test item may lead to the result of temporal behaviors similar to DES.
Moreover, organogenesis of the zebrafish liver begins between 60-72 hpf and the liver becomes visible at 96 hpf (Chu and Sadler, 2009). Consequently, it was considered that much of metabolic function was supposed to be obtained at approximately 96 hpf and the activity in the liver may have been mainly responsible for the decline of concentration of test item in embryos/larvae. Additionally, the activity of drug-metabolizing enzymes in the liver and/or in sites other than the liver might have partially contributed to the rapid decrease at 120 hpf and 144 hpf. No peaks other than test item were observed on the chromatogram obtained under the analytical conditions in this study.
Description of key information
Ammonium undecafluorohexanoate (CAS 21615-47-4) is expected to have a negligible potential to bioaccumulate based on the available data.
Key value for chemical safety assessment
Additional information
The potential of a substance for bioaccumulation is normally
described by its potential to assimilate in the lipid tissue of aquatic
organisms. The affinity of a substance to partition to the fat tissue
can be screened using the log Pow. A substance with a log Pow ≥ 4.5 is
considered to have a potential for bioaccumulation in fat tissue and the
bioaccumulation needs to be assessed further (ECHA, 2017). For
perfluorinated substances the log Pow is not considered to be an
adequate parameter to screen the bioaccumulation potential (ECHA, 2017).
Ammonium undecafluorohexanoate (CAS 21615-47-4) is the ammonium salt of
perfluorohexanoic acid. Due to the very low pKa value of 3.29 the
anionic form of the acid is the predominant form in the environment. In
aqueous medium NH3 generally exists in aqueous media as ammonium
hydroxide. The anionic functional group and the dipolar nature of the
carbon/fluorine backbone comprise to the hydrophobic as well as
lipophobic properties of the substance. Thus, the log Pow is considered
to be inappropriate to describe the accumulation potential of
perfluorinated compounds. Instead several studies have indicated that
perfluorinated substances tend to bind to proteins (proteinophilic)
instead of assimilating in lipid (ECHA, 2017; Conder et al., 2007). Due
to these very specific properties of the substance it is considered
necessary to investigate the bioaccumulation potential of
perfluorohexanoic acid in specific tissues of aquatic species and not
derive a bioconcentration factor based on whole body wet weight. This
might underestimate the bioaccumulation potential. Martin et al. (2003a)
investigated the potential bioaccumulation of several
perflurocarboxylates in fish during aqueous exposure under flow-through
conditions. The study was not performed according to an accepted
guideline but the study design is well described and comparable to OECD
Guideline 305. Juvenile rainbow trout were exposed to a mixture of
perflurocarboxylates with C-chains of C5 (perfluoropentanoic acid) to
C14 (perfluorotetradecanoic acid). Perfluorohexanoic acid was detected
in the test medium at a mean concentration of 1.7 µg/L (relative
standard deviation: 10%) throughout exposure. The exposure was split
into an uptake phase of 12 d and a depuration phase of 33 d. To
investigate the accumulation the fish were anesthetized. The gut,
consisting of esophagus, stomach, pyloric ceca, spleen, and intestines,
was removed but not analyzed. The blood, liver, and carcass samples were
analyzed separately for perflurocarboxylates at each sampling time to
determine the kinetics of uptake and depuration. Perfluorohexanoic acid
could not be detected in any of the analysed samples of carcass, blood
and liver assuming that the substance does not bioaccumulate. The
results from this study clearly show that bioaccumulation of
perflurocarboxylates is dependent on the chain length of the
carbon-fluorine backbone and the analysed tissue. Blood was found to be
the tissue with the highest bioconcentration factors (BCF). The BCF in
blood increased from 4.0 L/kg (C8) up to 40,000 L/kg (C12) and started
to decrease to 30,000 for perfluorododecanoic acid (C14). All BCF values
were corrected for growth to exclude any impact of growth dilution
during exposure. In conclusion this study clearly shows that the
perflorohexanoic acid (C6) does not bioaccumulate in fish via aqueous
exposure. This result is supported by a study performed by Yeung &
Mabury (2013). In this study juvenile rainbow trout (Oncorhynchus
mykiss) were exposed to two commercial products containing several
perfluorinated compounds (including perfluorohexanoic acid). The
concentration of perfluorohexanoic acid in the test medium during the
uptake phase was 44 ± 16 ng/L. Analysis of carcass and liver samples did
not reveal any uptake/accumulation from the aqueous phase in the
different tissues which is consistent with the study from Martin et al.
(2003a). Martin et al. (2003b) further investigated a potential
accumulation of perfluorohexanoic acid via dietary exposure. Juvenile
fish (Oncorhynchus mykiss) were exposed to spiked trout food during an
uptake phase of 24 d followed by a depuration phase of 41 d. A mixture
of the same perfluorocarboxylates as already used for the aqueous
exposure were mixed into trout food. Perfluorohexanoic acid was measured
in the food at a concentration of 0.52 µg/g. The analysed fish samples
(liver and carcass) did not contain perfluorohexanoic acid. Thus, it can
be assumed that the substance is not taken up by fish via dietary
exposure and biomagnification based on the diet is not expected. These
findings of limited bioaccumulation in fish can be supported further by
monitoring data from a marine environment. Thompson et al. (2011)
analysed water, sediment and biota samples for the occurrence of
different perfluorinated alkyl compounds. Perfluorohexanoic acid was
found in 100% of the analysed water samples in concentrations of 2.9 ±
0.4 ng/L (n=20) whereas the substance was not found in sediment samples
(n=10). Moreover, perfluorohexanoic acid could not be detected in all
biota samples (oysters, white ibis eggs, gull eggs, fish muscle and fish
liver). Although the substance was found in water it could not be
measured in any biota sample indicating that accumulation is negligible.
Moreover, Conder et al. (2008) concluded that perfluorinated substances
with a C-chain ≤ 7 do not bioaccumulate and do not biomagnify within the
food chain. BCF and BAF values from laboratory and field measurements
were analysed for C7, C8, C9, C10 and C11 perfluorinated acids and none
of the studies for C7 resulted in a potential for bioaccumulation.
In addition to the presented studies on the bioaccumulation of PFHxA an additional study investigated the uptake of the substance in fish larvae/embryo of Danio rerio (Nawaji, 2018). The study did not follow a standard guideline but a method described in a peer-reviewed journal. Fertilized eggs were exposed to concentrations of PFHxA of 100, 250 and 500 mg/L under static conditions for 6 d. The concentrations were maintained as confirmed by analytical measurements (101, 255 and 511 mg/L (geometric mean)). An increase of concentrations in organisms was obvious starting on day 2 in all three concentrations. After day 4 the concentrations in fish embryos/larvae decreased to approximately the level on day 1. This decrease of concentrations in tissue was explained by the beginning of the metabolic function in fish which normally starts after 60-72 h after fertilization. Thus, it is likely that metabolizing enzymes in the developing liver and/or other sites of the body may have partially contributed to the rapid decrease of concentrations on day 5 and 6. This study result supports the above findings that in most of the environmental tissue samples analysed no perfluorohexanoic acid was found. It further supports the hypothesis that organisms (e.g. fish) are capable to metabolize/excrete the substance efficiently.
Taking all information from laboratory and environmental monitoring into account it can be assumed that perfluorohexanoic acid has a low potential for bioaccumulation and biomagnification in the food chain.
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