Dioctyltin dilaurate

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018-2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Cross-reference

Cross-reference 1

Reference

Endpoint:

immunotoxicity: acute oral

Remarks:

Part of the OECD 414 study on the read across substance Dioctyltin oxide.

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017-2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Justification for type of information:

READ ACROSS
Hydrolysis under stomach condition (pH 1.2) of Diotyltin dilaurate into Dioctyltin oxide and lauric acid (cp. Section basic toxicokinetics: Nasshan, In vitro metabolism study)
Study for justification of read across is link via cross reference.

DIOCTYLTIN DILAURATE
Furthermore another study with dioctyltin dilaurate shows additional information regarding the immune toxicity.

Reason / purpose for cross-reference:

reference to other study

Reason / purpose for cross-reference:

other: Hydrolysis under stomach condition (pH 1.2)

Reason / purpose for cross-reference:

other: Main study (OECD 414, rat)

Qualifier:

equivalent or similar to guideline

Guideline:

EPA OPP 85-7 (Immunotoxicity)

Deviations:

not applicable

Principles of method if other than guideline:

see attached report: study performed as port of an OECD 414 study

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

other: Crl:WI(Han)

Sex:

female

Route of administration:

oral: feed

Vehicle:

other: in diet

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

72 h

Frequency of treatment:

in diet

Dose / conc.:

0 mg/kg diet

Remarks:

0 mg/kg bw/day

Dose / conc.:

5 mg/kg diet

Remarks:

0-4 mg/kg bw/day

Dose / conc.:

25 mg/kg diet

Remarks:

1.8 mg/kg bw/day

Dose / conc.:

200 mg/kg diet

Remarks:

11.8 mg/kg bw/day

No. of animals per sex per dose:

5 in control, low and mid dise, 4 in high dose group

Control animals:

yes, plain diet

Details on study design:

- Dose selection rationale:
Subpart of OECD 414 study in rat, test substance Dioctyltin oxide. So rationale for dose selection is the main study. Dose selection form outcome of former studies with Dioctyltin oxide ((Waalkens-Berendsen, OECD 422, DOTO)

- Rationale for selecting satellite groups:
Determination of immunotoxicity as maternal toxicity

- Post-exposure recovery period in satellite groups:
Not planed, but time of last exposure to necropsy showed recovery of the immune system of test animals

- Rationale for animal assignment (if not random):
Subpart of OECD 414 study in rat, test substance Dioctyltin oxide

- Other:
Immunophenotyping:
Immunophenotyping was performed on Immunotoxicity animals from blood samples (0.5mL in EDTA) during the predose phase and on Gestation Days 7 (24 hours after first dose), 8 (48 hours after first dose), 9 (72 hours after first dose) and 10 (prior to necropsy)

Cytokine Measurement:
Blood samples (0.5 mL in serum separator tubes) were collected from Immunotoxicity cohort animals during the predose phase and on Gestation Days 7 (24 hours after first dose), 8 (48 hours after first dose), 9 (72 hours after first dose) and 10 (prior to necropsy)

Observations and clinical examinations performed and frequency:

Immunophenotyping:
Immunophenotyping was performed on Immunotoxicity animals from blood samples (0.5mL in EDTA) during the predose phase and on Gestation Days 7 (24 hours after first dose), 8 (48 hours after first dose), 9 (72 hours after first dose) and 10 (prior to necropsy)

Cytokine Measurement:
Blood samples (0.5 mL in serum separator tubes) were collected from Immunotoxicity cohort animals during the predose phase and on Gestation Days 7 (24 hours after first dose), 8 (48 hours after first dose), 9 (72 hours after first dose) and 10 (prior to necropsy)

Positive control:

not required

Clinical signs:

not specified

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Description (incidence and severity):

In the moin OECD 414 study no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

In the moin OECD 414 study no effects observed

Food efficiency:

no effects observed

Description (incidence and severity):

In the moin OECD 414 study no effects observed

Ophthalmological findings:

not examined

Haematological findings:

not examined

Description (incidence and severity):

not reported at the moment, if findings, report in endpoint of main OECD study

Clinical biochemistry findings:

not examined

Description (incidence and severity):

not reported at the moment, if findings, report in endpoint of main OECD study

Urinalysis findings:

not examined

Behaviour (functional findings):

not specified

Immunological findings:

effects observed, treatment-related

Description (incidence and severity):

see section specific immunotoxic examinations

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

4ß percent of thymus decrease in high dose group

Gross pathological findings:

no effects observed

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Description (incidence and severity):

not reported at the moment, if findings, report in endpoint of main OECD study

Histopathological findings: neoplastic:

not examined

Description (incidence and severity):

not reported at the moment, if findings, report in endpoint of main OECD study

Other effects:

not examined

Description (incidence and severity):

not reported at the moment, if findings, report in endpoint of main OECD study

Details on results:

not reported at the moment, if findings, report in endpoint of main OECD study

Cell viabilities:

effects observed, treatment-related

Description (incidence and severity):

Blood
At gestation Day 9, activated B lymphocyte numbers (CD3-/CD45RA+/CD25+) were markedly higher than the control group animals (approximately 3 to 4 times for the majority of the animals) at the 11.8mg/kg/day dose level.
Other observed differences, were limited to several lymphocyte sub-populations and tended to be slight to moderate in nature. On gestation Day 9, moderate increases were noted for CD3+/CD8+/CD25+, CD3+/CD25+ and CD3+/CD4+/CD25+ cell counts in animals dosed 11.8mg/kg/day. When compared to the control group results, the aforementioned populations were +85%, +60% and +50% greater, respectively.
At gestation Days 8 and 10, all groups administered Dioctyltin Oxide, displayed slightly lower numbers and relative percentages of NK cells (CD3-/CD161a+) when compared to the control group, although results within the treated groups were relatively unchanged when compared to other sampling days. No other changes of note were observed on Days 8 and 10.
Cytokines
Results for serum concentrations of IL-2 varied from day to day, with almost all animals, across all groups including controls, displaying quantifiable results on Days 8 and 10, but no animals recording results above the lower limit of quantitation (LLOQ) on Day 10. No test article-related effect could be determined, as the frequency and magnitude of quantifiable IL-2 were similar across all groups, and comparable to the results observed during the pre-dose phase. Quantifiable results, where observed were either slightly above the LLOQ value, or at least within 3 times the LLOQ value.

Humoral immunity examinations:

not examined

Specific cell-mediated immunity:

not specified

Non-specific cell-mediated immunity:

not specified

Other functional activity assays:

not examined

Other findings:

not specified

Key result

Dose descriptor:

LOAEL

Effect level:

ca. 11.8 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Basis for effect level:

immunology

Key result

Dose descriptor:

NOAEL

Effect level:

ca. 1.8 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Basis for effect level:

immunology

Key result

Critical effects observed:

yes

Lowest effective dose / conc.:

11.8 mg/kg bw/day (nominal)

System:

immune system

Organ:

thymus

other: immune system

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

no

Conclusions:

The LOAEL for acute immune toxicity for Dioctyltin oxide was determined to be 11.8 mg / kg bw7day thus a NOAEL of 1.8 mg/kg bw7day results.

Cross-reference 2

Reference

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Objective of study:

metabolism

other: Hydrolysis under stomach conditions

Qualifier:

no guideline required

GLP compliance:

no

Specific details on test material used for the study:

Dioctyltin dilaurate

Radiolabelling:

no

Metabolites identified:

yes

Details on metabolites:

dimeric Distannoxane

Bioaccessibility (or Bioavailability) testing results:

There is no bioavailability of the dimeric Distannoxane based on a molecular mass of > 1000 DA

Conclusions:

DOTL in-vitro metabolism can be monitored using 119Sn-NMR Spectroscopy. Under the simulated gastric conditions (0.1 M HCl/pH 1.2/37°C) the tin resonance at -155 ppm characteristic to DOTL (Annex 1) disappeared completely indicating that DOTL has been used up within 0.5-4.0 hour of the experiment. Main products of the hydrolysis (Annex 2 and 3) are DOTLC, (DOTCL)2O and a DOTO complex. (DOTCL)2O was detected as two sharp peaks at -92 ppm and -145 ppm
Increasing the exposure time from 30 min. to 4 hours slightly increased the amount of DOTLC and decreased the amount of the DOTO complex (Annex 2 and 3).
Formation of the dialkytin mono-chloro carboxylates is described in literature 2). This type of hydrolytic behavior at low pH is consistent with the results obtained on hydrolysis of dialkyltinmecaptides4-6). The dialkyltin mono-chloro esters are formed under the same conditions rapidly and equilibrated with the initial dialkyltin mecaptides.

A broad signal at about 150 ppm was assigned to the DOTO complex. On one hand, the DOTO reference material results in a comparable chemical shift with a broad signal (Annex 6), on the other hand, DOTO is not known to be soluble in hexane. Therefore, the DOTO complex term in this study describes a hexane-extractable solution of DOTO in DOTLC or DOTL.
Alkyltincarboxylates are known for their rich structural variety which includes different ways of coordinating the carboxyl groups and tin atoms and their ability to form bridged chemical structures2,3). Additionally, bulky alkyl groups (such as octyl groups) on a tin atom of the dialkyltin oxides are known to form more soluble cyclic trimers as opposed to dialkyltin oxide polymers7).
Addition of a DOTC excess resulted in an instant reaction of the DOTO complex to DOTLC.
In order to check if any non-extractable by hexane tin compounds were formed as a result of DOTL in-vitro metabolism and remained in the aqueous phase, that phase was analyzed for a total tin content using AAS. The total tin content of the aqueous phase was found to be < 10 ppm (trace quantity).
In a hydrolysis study of Dioctyltin dilaurate with 0.1 M Hydrogenchloride (4h, 37 ^C) was identified a distannoxane as hydrolysis product. In an similar experiment with Dioctyltin dichloride also was identified a distannoxane as hydrolysis.
Based on 119Sn-NMR data and data from mass spectroskopy, the distannoxane is minimum monomeric with a mass > 1000 Da.
So even if formed by both substances (source and target) under low pH conditions this substance cannot pass the
membranes of the gastrointestinal tract and thus is toxicological not of relevance

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2020

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Version / remarks:

This study was designed to meet the requirements of the OECD test guideline 414
(adopted 25 June 2018)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Dioctyltin dilaurate

EC Number:

222-883-3

EC Name:

Dioctyltin dilaurate

Cas Number:

3648-18-8

Molecular formula:

C40-H80-O4-Sn

IUPAC Name:

dioctyltin dilaurate

Test material form:

liquid

Specific details on test material used for the study:

Lot number : VP19-120

Test animals

Species:

rat

Strain:

Wistar

Remarks:

Crl:WI(Han) from Charles River Laboratories, Margate, UK

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: Ground Purina Mills Certified Rodent Diet 5002

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/kg diet

Remarks:

ppm

Doses / concentrations 2

Dose / conc.:

20 mg/kg diet

Remarks:

ppm

Doses / concentrations 3

Dose / conc.:

80 mg/kg diet

Remarks:

ppm

Doses / concentrations 4

Dose / conc.:

500 mg/kg diet

Remarks:

ppm

No. of animals per sex per dose:

20 females

Control animals:

yes, concurrent vehicle

Examinations

Blood sampling:

Blood for toxicokinetic evaluations was collected prior to the initiation of dosing on
GD 6, approximately 24 (±1) hours after the initiation of dosing, and at necropsy on
GD 21

Fetal examinations:

The progress and outcome of pregnancy were evaluated, and
fetuses were examined for malformations and variations and fetal anogenital distances
were recorded

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Dermal irritation (if dermal study):

not examined

Mortality:

mortality observed, treatment-related

Description (incidence):

Test article-related unscheduled deaths occurred for animals provided with 500 ppm

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Adverse test article-related reductions in body weights were evident for animals
provided with 500 ppm

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Adverse test article-related reductions in food consumption were evident for animals
provided with 500 ppm, compared with controls

Endocrine findings:

effects observed, treatment-related

Description (incidence and severity):

Adverse test article-related reductions in thyroxine (T4) and increases in thyroid
stimulating hormone (TSH) were evident for animals provided with 500 ppm,
compared with controls.

Maternal developmental toxicity

Number of abortions:

no effects observed

Description (incidence and severity):

No Aborts observed.

Total litter losses by resorption:

effects observed, treatment-related

Description (incidence and severity):

Two females (Animals R0307 and R0313) provided with 500 ppm had total in utero
litter losses

Dead fetuses:

effects observed, treatment-related

Description (incidence and severity):

Adverse test article-related lower gravid uterus weights, and weight changes were
evident for females provided with 500 ppm, compared with controls. A higher
incidence of dead fetuses and lower fetal weights were also evident following
maternal exposure of 500 ppm, compared with controls, and considered adverse.

Effect levels (maternal animals)

Key result

Dose descriptor:

NOAEL

Effect level:

0.8 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

maternal abnormalities

Results (fetuses)

Anogenital distance of all rodent fetuses:

effects observed, treatment-related

Description (incidence and severity):

An adverse test article-related effect on anogenital distance was noted for male fetuses
maternally exposed with 500 ppm.
No effect on anogenital distance was evident for female fetuses maternally exposed
with 500 ppm or fetuses of either sex maternally exposed with 20 or 80 ppm.

External malformations:

effects observed, treatment-related

Description (incidence and severity):

Adverse test article-related fetal malformations and variations were observed
following maternal exposure of 500 ppm.

Effect levels (fetuses)

Key result

Dose descriptor:

NOAEL

Effect level:

3.9 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

not specified

Basis for effect level:

skeletal malformations

Remarks on result:

other: incomplete ossification of cervical arches

Fetal abnormalities

Abnormalities:

effects observed, treatment-related

Localisation:

external: limb

external: paw

external: anogenital distance

other: polydactyly

Description (incidence and severity):

Adverse test article-related fetal malformations and variations were observed
following maternal exposure of 500 ppm.

Overall developmental toxicity

Key result

Developmental effects observed:

no

Applicant's summary and conclusion

Conclusions:

Ad libitum dietary administration of control article (vehicle) or 20, 80, or 500 ppm
Dioctyltin dilaurate (equivalent to nominal dose levels 0, 0.8, 3.9, or 25.4 mg/kg/day,
respectively) to the pregnant rat from GD 6 through 21 resulted in adverse test
article-related effects for animals provided with 500 or 80 ppm, and adversely
affected the developing fetuses following maternal exposure of 500 ppm.
Based on the finding of this study, the no observed adverse effect level (NOAEL) for
maternal toxicity is 20 ppm.
Fetuses were not adversely affected by maternal exposure to 80 ppm; as such, the
NOAEL for embryo-fetal development is 80 ppm