Barium titanium trioxide

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Link to relevant study records

Reference

Reference 1

Endpoint:

extended one-generation reproductive toxicity – with F2 generation and both developmental neuro- and immunotoxicity (Cohorts 1A, 1B with extension, 2A, 2B, and 3)

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:

guideline study

Justification for type of information:

Barium titanates are effectively the barium salts of the unstable titanic acid (titanium hydroxide). Titanium hydroxide is hard to isolate without rapid hydrolysis to titanium dioxide and barium chloride. It is therefore proposed to base environmental and health assessment on these two hydrolysis products. There has been extensive research on similar substances in the ‘titanate’ grouping and these all exhibit similar behaviour in that under acid biological conditions (eg if ingested) or if dispersed in water, there is dissociation of the ions and subsequent hydrolysis / oxidation.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 443 (Extended One-Generation Reproductive Toxicity Study)

Deviations:

no

GLP compliance:

yes

Remarks:

Details of the actual laboratory are not given in this publication, but the fact the testing was carried out to GLP is confirmed.

Limit test:

no

Justification for study design:

Within the scope of the re-evaluation of titanium dioxide (E171) as a food additive by the European Food Safety Authority (EFSA) adopted on the 28th June 2016, the conduct of a “multigeneration or extended-one generation reproduction toxicity study according to the current OECD guidelines” was recommended. This study was requested in order to establish a health-based guidance value (ADI) for the food additive titanium dioxide. The study was required to be to OECD 443 and include all necessary testing Including of extension of Cohort 1B : Cohort 1B animals were mated to establish the F2 generation. This was done to investigate publications reporting several reproductive and developmental effects induced by titanium dioxide. Also, Inclusion of developmental neurotoxicity Cohorts 2A and 2B : the full range of neurodevelopmental toxicity was evaluated to investigate publications reporting several neurotoxic effects induced by titanium dioxide. Inclusion of developmental immunotoxicity Cohort 3 : the full range of developmental immunotoxicity was evaluated to investigate publications reporting several immunotoxic effects induced by titanium dioxide.

Specific details on test material used for the study:

food additive titanium dioxide(E 171)

Species:

rat

Strain:

not specified

Remarks:

In this published report, the strain of rat used was not specified

Sex:

male/female

Route of administration:

oral: feed

Details on exposure:

E 171 was administered via the diet.The concentration was adjusted weekly using the foodconsumption values from the previous week to maintain a constant dose level in relation to theanimals’body weights. The actual E 171 intake for each test week was reported in mg kg body weightper day and calculated from the relative food consumption per day and the nominal E 171concentration that was used in that test week

Analytical verification of doses or concentrations:

yes

Remarks:

The titanium levels in the control and test diets weredetermined by inductively coupled plasma optical emission spectroscopy (ICP-OES). The backgroundlevel of titanium in the diet was 17 mg Ti/kg diet (mean value) and ranged 11–31 mg Ti/kg diet

Frequency of treatment:

Daily as described below

Details on study schedule:

. In the F0 generation, E 171 was administered in the diet atdoses of 0, 100, 300 or 1,000 mg/kg bw per day from 10 weeks prior to mating until weaning of theF1 generation. The F1 generation received these diets from weaning until PND 4 or 8 of the F2generation. The F2 generation was exposed through the milk until the termination of the study on PND 4 or PND 8. Duration of dosing depended on the endpoints under evaluation in the differentcohorts, with the longest duration of treatment up to 18 weeks. Endpoints included were consistentwith those specified in OECD TG 443 guidance in order to ensure the investigation of reproductive anddevelopmental toxicity of E 171

Dose / conc.:

0 mg/kg bw/day

Dose / conc.:

100 mg/kg bw/day

Dose / conc.:

300 mg/kg bw/day

Dose / conc.:

1 000 mg/kg bw/day

No. of animals per sex per dose:

20/sex/group

Control animals:

yes, plain diet

Details on study design:

In the F0 generation, E 171 was administered in the diet atdoses of 0, 100, 300 or 1,000 mg/kg bw per day from 10 weeks prior to mating until weaning of theF1 generation. The F1 generation received these diets from weaning until PND 4 or 8 of the F2generation. The F2 generation was exposed through the milk until the termination of the study on PND 4 or PND 8. Duration of dosing depended on the endpoints under evaluation in the differentcohorts, with the longest duration of treatment up to 18 weeks.

Parental animals: Observations and examinations:

In the F0 parental animals, no premature death or changes in general behaviour or external appearance were noted in any treatment group of either sex. Pale faeces were noted at 300 and 1,000mg E 171/kg bw per day in both males and females. No difference in food consumption, body weightor body weight gain between control and treatment groups was observed in males and females duringpre-mating, gestation and lactation. A slight but statistically significant increase in water consumptionwas recorded in females at 100 mg E 171/kg bw per day. Considering the lack of dose–responserelationship, the temporary nature and the small magnitude, this effect was considered incidental andnot-treatment-related.

Litter observations:

In the F1 generation cohort 1A animals, no premature deaths or changes in general behaviour orexternal appearance were noted in any treatment group of either sex. Pale faeces were noted at 1,000mg E 171/kg bw per day in both males and females. A slight decrease in body weight was noted in males at 300 mg E 171/kg bw per day, reaching statistical significance on test days 36 and 64. Bodyweight gain was not affected at any other dose. Considering the lack of a dose–response relationship,its temporary nature and small magnitude, the decrease in body weight was considered incidental andnot treatment-related. No other effects on body weight, body weight gain and food consumption wereobserved in males and females at any dose.
In the F1 generation cohort 1B animals, no premature deaths or changes in general behaviour or external appearance were noted in any treatment group of either sex. Pale faeces were noted at 1,000mg E 171/kg bw per day in both males and females. A slight but statistically significant decrease inbody weight was noted in males at 300 mg E 171/kg bw per day, onfive non-consecutive testing days. Body weight gain was not affected at any dose. Considering the lack of dose–responserelationship, the temporary nature and the small magnitude, this effect was considered incidental andnot treatment-related. No other effects on body weight, body weight gain, food and waterconsumption were observed in males and females at any dose.In the F1 generation cohorts 2A and 2B animals, no premature deaths or changes in general behaviouror external appearance were noted in any treatment group of either sex. Pale faeces were noted at 1,000mg E 171/kg bw per day in both males and females. No effects on body weight or body weight gain werenoted. Transient statistically significant but inconsistent changes in food consumption were noted in bothsexes at all doses, but considering the lack of dose–response relationship, their temporary nature andsmall magnitude, these effects were considered incidental and not treatment-related

Key result

Dose descriptor:

NOAEL

Effect level:

>= 1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other:

Remarks on result:

not determinable due to absence of adverse toxic effects

Dose descriptor:

NOAEL

Effect level:

>= 1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other:

Remarks on result:

not determinable due to absence of adverse toxic effects

Dose descriptor:

NOAEL

Generation:

F1 (cohort 1A)

Effect level:

>= 1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other:

Remarks on result:

not determinable due to absence of adverse toxic effects

Dose descriptor:

NOAEL

Generation:

F1 (cohort 2A)

Effect level:

>= 1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other:

Remarks on result:

not determinable due to absence of adverse toxic effects

Dose descriptor:

NOAEL

Generation:

F1 (cohort 2B)

Effect level:

>= 1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other:

Remarks on result:

not determinable due to absence of adverse toxic effects

Dose descriptor:

NOAEL

Generation:

F1 (cohort 3)

Effect level:

>= 1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other:

Remarks on result:

not determinable due to absence of adverse toxic effects

Reproductive effects observed:

no

Conclusions:

Regarding the newly performed EOGRT study with E 171, the Panel concluded that there were noindications of general toxicity, no effect on thyroid or sex hormone levels, no effect on reproductivefunction and fertility in either male or female rats. Furthermore, no effects were observed on pre- andpostnatal development. No effects on neurofunctional endpoints in F1 offspring were observed either.Concerning immunotoxicity, a marginal but statistically significant decrease in antigen-induced IgMlevels (9%) in males of the F1 Cohort 3 only was noted, with no apparent dose-response. However,the Panel noted that there were methodological shortcomings in the design of this part of the EOGRTstudy. Therefore, the Panel could not conclude on immunotoxicity. In a satellite group of that study,E 171 at doses up to 1,000 mg/kg bw per day did not induce ACF in the colon. The Panel consideredthat there was uncertainty regarding the extent of the internal exposure to TiO2nanoparticles (presentin E 171) across the range of tested doses.

Reference 2

Endpoint:

screening for reproductive / developmental toxicity

Remarks:

based on test type (migrated information)

Type of information:

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

Adequacy of study:

key study

Study period:

no data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study well documented, meets generally accepted scientific principles, acceptable for assessment. Data and Rating according to the SIDS 2005 on barium cabonate. Deviances when comparing to OECD421: dosing only prior to mating, no individual animal data/tables provided, histopathologic examination, data on food consumption only provided for core study animals, no humidity, sex of pups, and data on stability of test substance in vehicle given. Only the average results of the controls and the high dose groups of each species were available.

Justification for type of information:

Research document on water-soluble form of barium salt. Both rats and mice examined
Considered suitable as source data for barium salts

Reason / purpose for cross-reference:

reference to same study

Qualifier:

no guideline followed

Principles of method if other than guideline:

In parallel with a subchronic toxicity core study, a premating study was performed with separate groups of rats and mice. Premating exposure period with Barium chloride dihydrate was 60 days for males and 30 days for females.

GLP compliance:

not specified

Species:

rat

Strain:

other: Fischer 334/N

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Simonson Laboratories, Gilroy, CA
- Age at study initiation: (P) 32 days
- Housing: five per cage in drawer-type polycarbonate cages (shelves covered with filter sheets, bedding, cages and water bottles were changed twice a week, feeders once a week, racks and filters every other week); after 60 days of exposure, the males were placed in individual cages and one female receiving the same dose level (but exposed for 30 days) was cohabited with the male. After mating the females were separated.
- Diet: NIH-o7 pellets (Ziegler Brothers, Gardners, PA)
- Water: ad libitum (dosed or undosed) for 92 consecutive days
- Acclimation period: 10 to 11 days (quarantined)


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 - 24 °C
- Air changes (per hr): 13.5 room vol.
- Photoperiod (hrs dark / hrs light): 12/12 (fluorescent lighting)

Route of administration:

oral: drinking water

Vehicle:

water

Details on exposure:

- Solutions were made weekly in 19-liter quantities by dissolving weighed portions of the test substance in glass-distilled water.
- Concentration in vehicle: 0, 1000 and 4000 ppm
- no further significant details stated

Details on mating procedure:

- M/F ratio per cage: 1 male / 1 female rat
- Length of cohabitation: up to one week
- Proof of pregnancy:Examination of microscopic evidence of sperm in vaginal swab every morning
- When evidence of mating was found, the females was separated from the male.
- After mating determinations were made on the eighth day of cohabition and all remaining pairs were separated.
- No remating was performed although pregnancy rate was low.
- no further significant details stated

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses were performed on all levels before and after use, and at the beginning and midway through the test period. The concentrations were within 1 to 6 % of the theoretical concentration. Method of analysis was not stated

Duration of treatment / exposure:

Premating exposure period: 60 days for males and 30 days for females

Frequency of treatment:

continuous

Dose / conc.:

1 000 ppm (nominal)

Dose / conc.:

2 000 ppm (nominal)

Dose / conc.:

4 000 ppm (nominal)

No. of animals per sex per dose:

20 each sex

Control animals:

yes, concurrent vehicle

Details on study design:

No remating was performed due to restriction in the study dosing schedule/design

Parental animals: Observations and examinations:

Yes, twice daily, including clinical, body weight, water and food consumption

Oestrous cyclicity (parental animals):

Evaluation of vaginal cytology was performed among treated and control groups.

Sperm parameters (parental animals):

Parameters examined in P male parental generations

Litter observations:

F1 offspring:
- at birth and day 5
- number of live litter, average litter size at day 0 and 5, pup survival to day 5, pup weight at birth and day 5, external abnormalities
- examination of dead pups

Postmortem examinations (offspring):

All surviving animals were terminated on days 96 and 97.

Clinical signs:

effects observed, treatment-related

Organ weight findings including organ / body weight ratios:

no effects observed

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

no effects observed

Reproductive performance:

no effects observed

Dose descriptor:

NOAEL

Effect level:

4 000 ppm (nominal)

Based on:

element

Sex:

male/female

Basis for effect level:

other:

Remarks on result:

not determinable due to absence of adverse toxic effects

Dose descriptor:

NOAEL

Effect level:

179.5 mg/kg bw/day (nominal)

Based on:

element

Sex:

female

Basis for effect level:

other:

Remarks on result:

not determinable due to absence of adverse toxic effects

Dose descriptor:

NOAEL

Effect level:

201.5 mg/kg bw/day (nominal)

Based on:

element

Sex:

male

Basis for effect level:

other:

Remarks on result:

not determinable due to absence of adverse toxic effects

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

4 000 ppm (nominal)

Based on:

test mat.

Sex:

not specified

Basis for effect level:

other:

Remarks on result:

not determinable due to absence of adverse toxic effects

Reproductive effects observed:

not specified

Only the average results of the controls and the high dose groups of each species were available.

No-observed-adverse-effect level (NOAEL) for fertility impairment was 4,000 ppm in rats. These NOAEL values correspond to average doses of 201.5 and 179.5 mg Ba/kg bw/d to male and and female rats, respectively.

A NOAEL on developmental toxicity of 4,000 ppm is also reported. However, the NOAEL is of limited value to evaluate the potential for barium to induce developmental effects. The reason for this limitation is based on the fact that the premating study design did not include exposure of female animals during the gestational period to barium chloride. Therefore, the premating study has to be considered as an inadequate study of developmental toxicity and cannot be used to determine the occurrence of developmental toxicity.

Conclusions:

Taken together all data of this study, there are no indications of a substantial impairment of fertility in rats up to the highest dose tested. Thus, the NOAEL was 4000 ppm (to average doses of 201.5 and 179.5 mg Ba/kg bw/d to male and and female rats, respectively). No-observed-adverse-effect levels (NOAELs) on developmental toxicity for rats of 4000 ppm were derived from this study. However, this NOAEL is of limited value to evaluate the potential for barium to induce developmental effects because there was no exposure of the females during gestation.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

304 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Additional information

There is a reliable in vivo study available to assess the potential of toxicity to reproduction of the analogous test substance barium dichloride dihydrate after oral administration.

For read-across barium chloride is adopted as it is also an inorganic barium salt whose relevant eco-/toxicological nature depends on the common cation barium whereas the toxicological nature of the anion is negligible. The substances differ in solubility. Barium chloride is soluble while barium titanium trioxide is slightly soluble. But this difference is considered as negligible as it is supported by the absence of any adverse findings in acute toxicity for the analogue substance. In conclusion, read-across for the endpoint toxicity to reproduction is justified.

Toxicity to reproduction – oral

In a non guideline conform study the potential of the analogous test substance barium dichloride dihydrate (purity: >99.5 weight-%) to assess the toxicity to reproduction after oral ingestion was carried out using Fischer 344 rats (Dietz et al., 1992).

The test substance was given to male rats 60 days and to female rats 30 days before mating period in the concentrations: 1000, 2000 and 4000 ppm.

One pregnant dam in the 4000 ppm dose group was terminated in a moribund state 21 days after mating.

No treatment-related effects of barium chloride dihydrate could be found on vaginal cytology, on epididymal sperm count, sperm motility and sperm morphology up to 4000 ppm.

The pregnancy rates were below generally accepted norms: from 40 % in the controls and 65 % in the 4000 ppm dose group. All pregnant dams produced litters except for one in the 4000 ppm dose group, which was terminated. Necropsy of the terminated dam revealed 7 foetuses and one resorption site.

The average gestation period of surviving dams was in the normal range.

The number of implants per pregnant dam was marginally reduced in the 4000 ppm dose group compared with the controls (but without statistical significance at p<0.05)

No effect could be detected on testis or epididymal weight.

Pup survival to day 5 was 99 % or greater in all treatment groups. No external abnormalities were observed in the rat offspring. Rats receiving 4000 ppm exhibited significant although marginal reductions in pup weights at birth (5.20 +/- 0.06 g compared to 5.70 +/- 0.09 g); a comparison of pups weight on day 5 showed no significant differences. Weight gain was comparable among all pup groups.

The average litter size at birth and on postpartum day 5 was marginally reduced in the 4000 ppm dose group compared with the controls (but without statistical significance at p<0.05).

Taken together all data of this study, there are no indications of a substantial impairment of fertility in rats up to the highest dose tested. Thus, the NOAEL was 4000 ppm (to average doses of 201.5 and 179.5 mg Ba/kg bw/d to male and female rats, respectively).

Based on this screening study the NOAEL of Ba 2+ ions is 179.5 mg /kg bw/day for female rats resultant a NOAEL of barium titanium trioxide for fertility impairment of ≥ 304 mg/kg bw/day (calculated from its molecular weight).

Under the conditions of this screening test, barium titanium trioxide is considered not to be toxic to reproduction in rats.

Short description of key information:
Toxicity to reproduction - oral:
read-across, key study, oral, Fischer 344 rats; NOAEL ≥ 103 mg/kg bw/d (no guideline followed, Dietz et al., 1992)

Justification for classification or non-classification

Classification, Labeling, and Packaging Regulation (EC) No. 1272/2008:

Based on the results, the classification of the test substance for toxicity to reproduction under Regulation 1272/2008 is not warranted.