Calcium didocosanoate

Repeated dose toxicity: oral

Administrative data

Endpoint:

chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP-status not known, guideline not known, published in a regulatory document. Only a summary of the study is available, limitations in design and/or reporting but otherwise adequate for assessment.

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Screening-level hazard characterisation: Lubricating grease thickeners category

Author:

US Environmental Protection Agency

Year:

2011

Bibliographic source:

Hazard characterisation document

Reference 2

Reference Type:

publication

Title:

Robust summary of information on grease thickeners

Author:

American Petroleum Institute

Year:

2008

Bibliographic source:

Petroleum High Production Volume (HPV) Testing Group (www.petroleumhpv.org/pages/greases)

Reference 3

Reference Type:

publication

Title:

Magnesium stearate given perorally to rats: A short term study

Author:

Sondergaard D, Meyer O, Wurtzen G

Year:

1980

Bibliographic source:

Toxicology, vol. 17, pp. 51-55 cited in API (2008)

Materials and methods

Principles of method if other than guideline:

- Method: Magnesium stearate was added to rat semi-synthetic diets in replacement of carbohydrates for 12 weeks and weight gain and necroscopic observations were recorded.

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Magnesium stearate

IUPAC Name:

Magnesium stearate

Constituent 2

Reference substance name:

Magnesium distearate

EC Number:

209-150-3

EC Name:

Magnesium distearate

Cas Number:

557-04-0

Molecular formula:

C18H36O2.1/2Mg

IUPAC Name:

magnesium dioctadecanoate

Test material form:

not specified

Details on test material:

No data reported

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

- Age at test initiation: 6 weeks

Administration / exposure

Route of administration:

oral: feed

Vehicle:

not specified

Details on oral exposure:

- Administration: For three months, magnesium stearate was administered via the diet at 0, 5, 10 and 20 % in substitution of the carbohydrates.

Analytical verification of doses or concentrations:

not specified

Details on analytical verification of doses or concentrations:

No data reported

Duration of treatment / exposure:

- Exposure period: 3 months (12 weeks)

Frequency of treatment:

No data reported

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
~2500 mg/kg-bw/day
Basis:
nominal in diet

Doses / concentrations 2

Remarks:

Doses / Concentrations:
~5000 mg/kg-bw/day
Basis:
nominal in diet

Doses / concentrations 3

Remarks:

Doses / Concentrations:
~10000 mg/kg-bw/day
Basis:
nominal in diet

No. of animals per sex per dose:

- Number of animals: 20 /sex/dose

Control animals:

yes

Details on study design:

- Diet: Rats were fed a semi-synthetic diet in which casein was replaced with sodium caseinate. The 0, 5, 10 and 20 % magnesium stearate diets contained 67.3, 62.3, 57.3 and 47.8% carbohydrates respectively. Acidified water (pH 3.5) were available ad libitum.

Positive control:

No data reported

Examinations

Observations and examinations performed and frequency:

- Observations: Body weights were measured weekly. Blood samples of 8 male and 8 females were taken at test initiation, 8 weeks and test termination and clinical and hematological chemistry was recorded.
- Hematological observations: Hemoglobin, packed cell volume, red cell count, total white cell count, reticulocyte count, differential white cell count
- Clinical chemistry observations: Glucose, urea, aspartate amino transferase, alkaline phosphatase

Sacrifice and pathology:

- Observations: At test termination, organ weights were recorded and microscopic examination was undertaken of the organs and tissues of the highest treatment and control.
- Organ weight measurements: Thymus, liver, kidneys, adrenals, testes/ovaries, heart, lungs, brain and pituitary
- Tissue samples for light microscopy: urinary bladder, stomach, duodenum, pancrease, jejunum, cecum, colon, thyroid, parathyroid, triceps, brachial muscle, ischiadic nerve, axillar lymph node, uterus, sternum, eye, Harderian gland, skin and submandibular gland

Other examinations:

No data reported

Statistics:

No data reported

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Mortality was observed in 4 high-dose males due to stone formation in the lower urinary pathways.

Mortality:

mortality observed, treatment-related

Description (incidence):

Mortality was observed in 4 high-dose males due to stone formation in the lower urinary pathways.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

All high-dose males showed decreases in body weight gain.

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not specified

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

High-dose males showed statistically significant reductions in packed cell volume.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

High dose males showed a decrease in liver glycogen and high-dose males and females showed increases in iron in the liver.

Urinalysis findings:

not specified

Behaviour (functional findings):

effects observed, treatment-related

Description (incidence and severity):

All high-dose males showed increases in quietness, incontinence and unsteady movements.

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Statistically significant differences were observed at all dose levels in male relative liver weights and female relative kidney weights.

Gross pathological findings:

not specified

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

- Necroscopy: Changes were observed in the renal pelvis and lower urinary pathways during the autopsy at test termination of 5 surviving animals (4 males and 1 female) from the 20% treatment due to stone formation. Nephrocalcinosis was observed in 12/20 control males and all control females (with it considered to be severe in 18 females). In the 20% treatment group, 19/20 females showed slight to moderate nephrocalcinosis and 7/20 males were affected only slightly.
- Hematology: 20% treatment males showed statistically significant reductions were observed in packed cell volumes
- Organs: When compared to the controls, significant changes (p<0.05) in liver weight were observed in males at 5, 10 and 20% treatments and 20% treatment females. Significant changes in kidney weight were observed in males at the 10% treatment and in females at the 5, 10 and 20% treatment groups. Various amounts of iron deposition was observed in the kidneys and livers, though the males and females in the 20% group both showed increased iron deposition. The 20% treatment males showed a marked decrease in liver glyocgen but no differences were observed in the females. No effects were reported for reproductive organ weights or histology for treated males or females.
- Clinical signs: After 8 weeks, body weight gains were significantly lower in the 20% treatment males than in the controls. The highest treatment males also showed slow and unsteady movement with quiet behaviour and one male was incontinent. The surviving males showed receding symptoms in the last 4 weeks. No clinical effects were observed in any females in any groups.
- Mortality: Within the first 2 months, 4 males in the 20% treatment group died, with their deaths considered to be related to the stone formation observed in the lower urinary pathways of all 4 animals
- Comparison with controls: Nephrocalcinosis has been observed to be common in animals fed semi-synthetic diets and the reduction in nephrocalcinosis of high-dose animals compared to the control may be a result of increased magnesium in the diet. Diets with increased magnesium content have also previously been shown to be associated with greater incidence of stone formation in the lower part of the urinary track.

Effect levels

1

Dose descriptor:

LOAEL

Effect level:

ca. 10 000 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: According to US EPA (2011). Based on mortality and haematological effects in males and possible signs of liver toxicity in males and females. Corresponding to 20% magnesium stearate in the diet.

2

Dose descriptor:

NOAEL

Effect level:

ca. 5 000 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: According to US EPA (2011). Corresponding to 10% magnesium stearate in the diet.

3

Dose descriptor:

NOAEL

Effect level:

2 500 mg/kg diet

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: According to API (2008). Based on liver weight. Corresponding to 5% magnesium stearate in the diet.

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

A 3 month study of approximately 2500, 5000 and 10000 mg/kg-bw/day magnesium stearate administered via the diet to Wistar rats (20/sex/dose) led to a LOAEL of ~10,000 mg/kg-bw/day based on mortality and hematological effects in males and possible signs of liver toxicity in males and females and a NOAEL of ~5000 mg/kg-bw/day.

Executive summary:

A 3 month study repeated dose oral toxicity used approximately 2500, 5000 and 10000 mg/kg-bw/day magnesium stearate administered via the diet to Wistar rats (20/sex/dose). According to the US EPA (2011), this led to a LOAEL of ~10,000 mg/kg-bw/day, corresponding to 20% magnesium stearate in the diet, based on mortality and hematological effects in males and possible signs of liver toxicity in males and females and a NOAEL of ~5000 mg/kg-bw/day, corresponding to 10% magnesium stearate in the diet. According to the API (2008), the NOEAL was 2500 mg/kg body weight, corresponding to 5% magnsium stearate in the diet based on liver weight. Only a summary of the study is available, with no information on the test methods used. However, this information is taken from regulatory documents (US EPA 2011, API 2008) and can be considered adequate for use for this endpoint.