Diutan gum

Toxicity to reproduction

Administrative data

Endpoint:

two-generation reproductive 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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well reported, GLP-compliant study of a close chemical analogue, performed in general accordance with the relevant OECD test guideline (deviations insufficient to affect reproductive performance assessment).

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1985

Report date:

1985

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)

Deviations:

yes

Remarks:

Gross pathology examinations only at necropsy (except for malformed pups, those born dead and those dying before day 7). No histopathology examinations or organ weights.

GLP compliance:

yes

Remarks:

GLP Compliance statement included

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Gellan gum

EC Number:

275-117-5

EC Name:

Gellan gum

IUPAC Name:

Gellan gum

Details on test material:

Gellan gum (EC 275-117-5): blend of 5 production samples, mean polysaccharide content 58.5% .

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

Individually housed in stainless steel, wire mesh-bottomed cages except during mating (paired) or littering females (clear plastic cages). Free access to tapwater, fed powdered diet. Maintained at 21 +/- 3 degrees C, RH 50 +/- 20% (target values: minor excursions from targets only) and with photoperiod 12 hours light/12 hours dark.

Administration / exposure

Route of administration:

oral: feed

Vehicle:

other: test substance mixed with basal diet

Details on exposure:

Test diets prepared weekly by mixing test substance and basal diet in blender.

Details on mating procedure:

Each female paired with one male for maximum 7 days, with daily checking for sperm in vaginal lavage. If unmated, given up to two more 7-day pairings with unmated males from the same group.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Stability and homogeneity of test substance in diet confirmed pre-test. During test period, samples taken for analysis in weeks 1,4,8,12,16,22,27,31,36.

Duration of treatment / exposure:

P generation males fed test diet for 70 days prior to mating, through mating and for at least 3 more weeks until termination. P females treated for 14 days pre-mating then through mating, gestation and lactation.
F1 generation treated from weaning (day 21 post-partum) for at least 80 days prior to mating then (females) through gestation, parturition and lactation.
F2 generation terminated at weaning (no direct treatment).

Frequency of treatment:

Continuous via consumption of test diet

Details on study schedule:

F1 pups separated from mothers on day 21 post-partum: 2 males, 2 females/litter randomly selected and housed separately until end of weaning, then 26 males + 26 females/group randomly selected for mating. These F1 rats treated for 80-97 days in all prior to mating (then through to termination).
F2 pups terminated after weaning (day 21 post-partum).

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
2.5%
Basis:
nominal in diet

Doses / concentrations 2

Remarks:

Doses / Concentrations:
3.8%
Basis:
nominal in diet

Doses / concentrations 3

Remarks:

Doses / Concentrations:
5%
Basis:
nominal in diet

No. of animals per sex per dose:

26 males + 26 females (P and F1)

Control animals:

yes, plain diet

Positive control:

No

Examinations

Parental animals: Observations and examinations:

Daily observations, weekly detailed examinations plus 3 times daily checks for parturition.

Oestrous cyclicity (parental animals):

Daily examination of vaginal lavage.

Sperm parameters (parental animals):

Observation of sperm in vaginal lavage gave day 0 of gestation.

Litter observations:

Live and dead pups recorded at completion of littering. Malformed pups terminated: these plus stillbirths preserved for internal examination, together with all culled pups (litters reduced to 5 males, 5 females where possible).
Daily observations.
Bodyweights recorded on days 0,7,14 and 21 post-partum.

Postmortem examinations (parental animals):

Gross examinations (internal and external) at necropsy.
Uterine implantation sites recorded.

Postmortem examinations (offspring):

Detailed internal examination (including eyes, brain and other organs) for pups malformed, born dead or dying before day 7 post-partum.
Gross examinations at necropsy (10 males, 10 females/group selected 21-23 days post-partum).

Statistics:

Student's t-test (bodyweights and food intakes).
Kruskal-Wallis, Mann-Whitney U tests (days of mating, post-implantation loss, litter data).
Fisher's exact test or chi-square test (reproductive indices, gestation index).

Reproductive indices:

Mating index (% of paired females which mated)
Fertility index (% of paired females found pregnant)
Conception rate (% of females confirmed mated found pregnant).

Offspring viability indices:

Gestation index (% of pregnant rats giving birth to live pups).
Post-implantation loss (implantation sites - live births/implantation sites x 100)
Viability index (% of day 0 live pups surviving to day 4)
Lactation index (% of day 4 live pups surviving to day 21).

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

no effects observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Organ weight findings including organ / body weight ratios:

not examined

Histopathological findings: non-neoplastic:

not examined

Other effects:

effects observed, treatment-related

Description (incidence and severity):

Test substance intake: Achieved intake decreased over 10 treatment weeks. At 5% in diet intake g/kg/day was: P 6.0-3.0(M) 4.2-4.1(F), F1 6.5-2.8(M) 6.7-3.5 (F).

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Details on results (P0)

No treatment-related effects on bodyweight, food consumption, gross pathology, oestrus cycle, mating and fertility indices or gestation/parturition parameters.

Effect levels (P0)

Dose descriptor:

NOEL

Effect level:

5 other: % in diet

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No evidence of parental toxicity and no effect on reproductive performance seen at highest treatment level (5%)

Results: F1 generation

General toxicity (F1)

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Sexual maturation:

no effects observed

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

Details on results (F1)

No effects on fertility/reproduction parameters (F1) or on development (F1, F2).

Effect levels (F1)

Dose descriptor:

NOEL

Generation:

F1

Effect level:

5 other: % in diet

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No evidence of toxicity, no effect on reproductive performance and no effect on development of F1 rats seen at the highest treatment level (5%)

Results: F2 generation

Effect levels (F2)

Dose descriptor:

NOEL

Generation:

F2

Effect level:

5 other: % in diet

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No effects on F2 development seen at the highest treatment level (5%)

Overall reproductive toxicity

Reproductive effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Administration of gellan gum to P and F1 rats at levels up to 5% in diet resulted in achieved adult intakes within the range 2.8-6.5 g/kg (males), 3.0-4.2 g/kg (females). No evidence of toxicity or adverse effects on reproductive performance or development was seen. Given the close similarity between gellan gum and Diutan, it is reasonable to predict that Diutan would show a similar lack of toxicity to reproduction.