Tin dioxide

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

according to guideline

Guideline:

OECD Guideline 305 (Bioaccumulation in Fish: Aqueous and Dietary Exposure) -III: Dietary Exposure Bioaccumulation Fish Test

GLP compliance:

not specified

Remarks:

no available information on GLP compliance. Data are published

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
Metal concentrations (As, Cd, Cr, Co, Cu, Fe, Pb, Mn, Mo, Ni, Se, Sn, V, Zn) were determined in marine mussel tissue collected from a Class A shellfish production site off the west coast of Ireland (used in EXP2) and effluent exposed marine mussels from the highly contaminated site off the east coast of Ireland (used in EXP3).

Details on sampling:

- Sampling intervals/frequency for test organisms:juvenile rainbow trout were fed blue mussels collected from a Class A pristine site and
an effluent-impacted river estuary, over a period of 28 days. Selected elements (As, Cd, Cr,Co, Cu, Fe, Pb, Mn, Mo, Ni, Se, Sn, V, Zn) were determined in the mussels and fish tissues (muscle and skin) collected at 0, 14 and 28 days.
- Details on sampling and analysis of test organisms and test media samples (e.g. sample preparation, analytical methods):Fish (n=3) were sampled from the acclimation tank before the first day of exposure (0 d) as a control and from each of the nine exposure tanks after 14 days (14 d) and 28 days (28 d) offeeding (n=9 per exposure). Fish were individually caught with a net, sacrificed and lengthand weight measurements were recorded. Fish fillets (average weight of 12 g×2) werecollected at each sampling time point, dissected and placed in labelled plastic bags. All samples were transported back to the laboratory on dry ice and frozen at -80 °C for subsequent analysis.
Mussel and fish samples were washed with Milli-Q water [18.3 M·cm, Millipore, Bedford,USA] to remove debris and any adhering particulate material and all samples were freezedried at -52 °C [FreeZone 12, Labconco, Missouri, USA]. Fish samples were separated into muscle and skin tissues and pulverised in an agate ball mill (Fritsch™ Pulverisette 6 Planetary Mono Mill). Aliquots of tissue (approximately 0.25 g) were decomposed and mineralised using closed vessel microwave digestion (Multiwave 3000, Anton Paar, Graz,Austria (Ratcliff et al., 2016)) in a class 10,000 (ISO class 7) clean room using 3 mL of 67-69% HNO3 [SpA grade, Romil™, Cambridge, UK] and 3 mL of 30% H2O2 [TraceSelect®Ultra, Sigma-Aldrich, St. Louis, USA].

Details on preparation of test solutions, spiked fish food or sediment:

Juvenile rainbow trout, (Oncorhynchus mykiss, Walbaum, 1752, Salmoniformes,Actinopterygii, approximate weight 50±15 g), were sourced from a pond system fish farm facility (Roscrea, Ireland) and acclimatised for 13 days in one large tank of carbon filtered municipal supply water. A flow-through system was established for nine 70 L aerated, glass covered tanks, using the same water supply set at a flow rate of 0.2 L min-1.
Six fish were weighed and transferred into each tank to acclimatise for a further 24 h to reduce stress levels before exposure initiation.
During acclimatisation, fish were fed Nutra Parr 1.8 fish feed pellets (Skretting UK,Northwich) daily at 1-2% of total fish weight. The experimental design included nine exposure tanks i.e. three control tanks (EXP1) in which fish continued to feed on the commercial Nutra Parr 1.8 pellets, three mussel control tanks in which fish were fed wild blue mussels (Mytilus edulis) sourced from a Class A shellfish production area under EC Regulation 854/2004 (<230 E. coli per 100 g of bivalve mollusc flesh and intra-valvular fluid. off the west coast of Ireland, and three exposed mussel tanks (126 EXP3) in which fish were fed wild blue mussels (Mytilus edulis) collected from an effluent wastewater exposure site on the east coast of Ireland.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: Juvenile rainbow trout
- Strain: oncorhynchus mykiss, Walbaum, 1752, Salmoniformes, Actinopterygii
- Source: sourced from a pond system fish farm facility (Roscrea, Ireland)
- Weight at study initiation (mean and range, SD): approximate weight 50±15 g
- Feeding during test
- Food type: blue mussels (Mytilus edulis) collected from an effluent wastewater exposure site on the east coast of Ireland. The mussels chosen for this study were of the same size class (4-6 cm)
- Frequency: the elements (Sn) collected at 0, 14 and 28 days.
- Amount: Bagged mussel feed was removed from the freezer, cut into small frozen pellets and fed to the corresponding tanks. All tanks were fed daily at 2% of the total fish weight present in the tank.
ACCLIMATION
- Acclimation period and conditions: acclimatised for 13 days in one large tank of carbon filteredmunicipal supply water. Six fish were weighed and transferred into each tank to acclimatise for a further 24 h to reduce stress levels before exposure initiation. TEST ORGANISM
- Common name: Juvenile rainbow trout
- Strain: Oncorhynchus mykiss, Walbaum, 1752, Salmoniformes, Actinopterygii
- Source: Sourced from a pond system fish farm facility (Roscrea, Ireland)
- Weight at study initiation (mean and range, SD): 47-54 g
- Weight at termination (mean and range, SD): For the controlled fish feed study (EXP1), growth measured highest at 37e50%. In comparison, the mussel control study (EXP2) measured growth between 0 and 16% and the mussel exposure study (EXP3) measured growth between 0 and 4%.
- Method of breeding: pond system fish farm facility (Roscrea, Ireland) and acclimatised for 13 days in one large tank of carbon filtered municipal supply water
- Health status:
- Description of housing/holding area:
- Feeding during test
- Food type: blue mussels (Mytilus edulis) collected from an effluent wastewater exposure site on the east coast of Ireland. The mussels chosen for this study were of the same size class (4-6 cm)
- Amount: Bagged mussel feed was removed from the freezer, cut into small frozen pellets and fed to the corresponding tanks. All tanks were fed daily at 2% of the total fish weight present in the tank.
- Frequency: the element (Sn) collected at 0, 14 and 28 days.

ACCLIMATION
Acclimatised for 13 days in one large tank of carbon filteredmunicipal supply water. Six fish were weighed and transferred into each tank to acclimatise for a further 24 h to reduce stress levels before exposure initiation.

Route of exposure:

feed

Test type:

flow-through

Water / sediment media type:

other: ultra-pure water

Total exposure / uptake duration:

28 d

Test temperature:

Temperature measurements taken for each tank during 28-day exposure: 13 - 15.6 °C

pH:

pH measurements taken for each tank during 28-day exposure: 6.6 - 7.6

Dissolved oxygen:

Dissolved oxygen measurements taken for each tank during 28-day exposure:
Dissolved oxygen measured in tanks (% saturation): 86 - 95

Details on test conditions:

TEST SYSTEM
Mussel and fish samples were washed with Milli-Q water [18.3 M·cm, Millipore, Bedford,
USA] to remove debris and any adhering particulate material and all samples were freeze155 dried at -52 °C [FreeZone 12, Labconco, Missouri, USA]. Fish samples were separated into muscle and skin tissues and pulverised in an agate ball mill (Fritsch™ Pulverisette 6 Planetary Mono Mill). Aliquots of tissue (approximately 0.25 g) were decomposed and mineralised using closed vessel microwave digestion (Multiwave 3000, Anton Paar, Graz, Austria (Ratcliff et al., 2016)) in a class 10,000 (ISO class 7) clean room using 3 mL of 67-
69% HNO3 [SpA grade, Romil™, Cambridge, UK] and 3 mL of 30% H2O2 [TraceSelect®
Ultra, Sigma-Aldrich, St. Louis, USA].



OTHER TEST CONDITIONS
- For OECD 305 part III (dietary exposure fish bioaccumulation), overall daily feeding rate used in the study: Bagged mussel feed was removed from the freezer, cut into small frozen pellets and fed to the corresponding tanks. All tanks were fed daily at 2% of the total fish weight present in the tank. For the control tanks, fish were fed commercial fish feed pellets at the same quantities fed to the fish in the mussel control and exposure tanks
Fish faeces were removed approximately 6 h after feeding by siphoning from the base of the tank system.

Reference substance (positive control):

yes

Details on estimation of bioconcentration:

BASIS INFORMATION

- Monitoring data:Mussels from both sites were found to contain all of the selected metals with tin measuring lowest at <0.1 μg g-1 dry weight.
Tin was measured in the effluent-exposed mussels (EXP3) at concentrations at least three times those detected in the mussels collected from the Class A site (EXP2) but this difference was not observed in the fish muscle or skin following dietary exposure.

Remarks on result:

other: The calculated endpoint is the BAC (Background Assessment Concentration)

Details on results:

- Mortality of test organisms: no mortality occurred.
- Observations on body length and weight: the controlled fish feed study (EXP1), growth measured highest at 37e50%. In comparison, the mussel control study (EXP2) measured growth between 0 and 16% and the mussel exposure study (EXP3) measured growth between 0 and 4%.
- Reproduction during test period:
- Organ specific bioaccumulation: tin concentrations did not change significantly at 28 d but instead displayed significant differences for concentrations measured in muscle(tin was not detected in fish muscle) and skin tissues,at 14 d across exposure types and over the first and latter half of the 28-day period within each exposure

Tin was not detected in muscle after 14d and 28 day of exposure.

Metal	Average concentration in fish muscle (μg g-1 dry weight) ± S.D.
	0d	14d EXP 1	14d EXP2	14d ExP 3	28d EXP1	28 EXP2
Sn	nd	nd	nd	nd	nd	nd

Conclusions:

It has been noted that tin concentrations did not change significantly at 28 d but instead displayed significant differences for concentrations measured in muscle(tinwas not detected in fish muscle) and skin tissues, at 14 d across exposure types and over the first and latter half of the 28-day period within each exposure.
Tin content measured in the effluent-exposed mussels (EXP3) at concentrations at least three times those detected in the mussels collected from the Class A site (EXP2) but this difference was not observed in the fish muscle or skin following dietary exposure.

Executive summary:

Tin concentrations detected in mussel and fish tissues are measured against several assessment criteria, namely

environmental quality standards (EQSs) set by the EU WFD, background assessment concentrations (BACs) set by the OSPAR CEMP and guide values set by the EC Regulation for shellfish tissues.

Mussels from both sites were found to contain all of the selected metals with tin measuring lowest at <0.1 mg g-1 dry.

As mussels can be consumed directly by humans it is important to note that all of the metal residues measured in the

mussel tissues collected from both sites were below specified MRL values (European Commission Regulation 1881/2006) and deemed fit for human consumption.

It can be concluded that Tin as available in the aquatic syste, is unlikely to pose a risk to predatory organisms or humans exposed via the environment

Reference 2

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Justification for type of information:

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The main assumption for this read across approach is that the source substance ionic Tin and the target substance Tin (IV) dioxide NP have a common moiety (Tin ion).
Differences in the valence of atom Sn are expected to exert little effect on the physical chemical properties of Tin (II) oxide and Tin (IV) dioxide NP, which indicates their behaviour in the aquatic system should be similar.
Minor differences between Tin (II) and Tin (IV) in their absorption and distribution indicate that Tin (II) may be a bit more toxic than Tin (IV). In addition, soluble inorganic tin like Tin (IV) chloride, Tin (II) fluoride, and Tin (II) chloride with higher water solubility and content of halogen is more toxic than insoluble tin oxides, regardless the dimension. It has to be noted that Tin dioxide bulk form and the Tin Dioxide NP are both highly insoluble in water. This support a read-across argument.
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Please refer to test item sections for details.
3. ANALOGUE APPROACH JUSTIFICATION
A reliable aquatic bioaccumulation (dietary exposure) study on fish is available for the source substance ionic Tin, showing that the substance does not bioaccumulate (Tin detected in mussels and fish after 14d and 28 day of exposure never exceeded the BAC).
Since the target Tin Dioxide NP and the source (Tin compounds) substance dissociate to the same ion, both target and read-across substance, do share the same toxicological mechanisms and the effects of the target substance is predicted to be equal to the effects of the source substance.
The common compound ionic Tin is solely responsible for the absence or presence of effects.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 305 (Bioaccumulation in Fish: Aqueous and Dietary Exposure) -III: Dietary Exposure Bioaccumulation Fish Test

Remarks on result:

other: The reported endpoint is the BAC (Background Assessment Contration)